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I
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HANDBOOK OF SHIP CALCULATIONS,
CONSTRUCTION AND OPERATION
A BOOK OF REFERENCE FOR SHIPOWNERS, SHIP
OFFICERS, SHIP AND ENGINE DRAUGHTSMEN.
MARINE ENGINEERS, AND OTHERS ENGAGED
IN THE BUILDING AND OPERATING OF SHIPS
r
BY
CHARLES H. HUGHES
NAVAL ARCHITECT AND ENGINEER
D. APPLETON AND COMPANY
NEW YORK LONDON
1917
Digitized by VjOOQ LC
A'
V^
COPTRIOHT, 1917, BT
D. APPLETON AND COMPANY
Printed in the United States of America
Digitized
PREFACE
This handbook has been compiled with the purpose of
assembling in a single publication in convenient form, practical
data for everyday reference, for men engaged in the designing,
building and operating of ships. Theoretical calculations have
been purposely omitted.
Shipowners and men in the offices of steamship companies will
find particular interest in the sections on Loading and Stowing
of Cargoes, Maintenance, Ship Chartering, and Marine Insurance.
To men employed in shipyards the sections on Ship Calcula-
tions and Hull Construction, Structural Details, Machinery,
and Ship Equipment, and the various formulae for making quick
calculations will be of use. In making preliminary designs the
section on Hull and Machinery Weights, as also the tables giving
particulars of all classes of vessels, will be found convenient.
Ship officers and marine engineers will find, in the section on
Machinery, valuable data on the overhauling of boilers, on indi-
cator cards, on the operating of pumps, condensers and motors,
and many other practical subjects: They will find useful also
the sections on Loading and Stowing of Cargoes, Ship Machinery,
and many other subjects.
Marine underwriters, ship brokers and freight brokers will find
convenient data on ship construction and the stowage sizes of
materials, with a large number of miscellaneous tables.
For men engaged in the designing and building of war vessels
a section on warships has been included, which describes . the
different classes and their armor and armament. Although the
fundamental calculations for all' vessels, merchant and war, are
the same, the text contains frequent special references to war-
ships, as on the subject of electric propulsion, electric steering
gears, electric winches, etc.
To the student of naval architecture and marine engineering
this handbook offers a broadeF«onUfct«0i^ of practical data than
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vi Preface
any other published work. The very latest marine practice is given,
and such subjects as electric propulsion, geared turbines, Diesel
engines, and oil fuel are fully treated, as are also recent and special
types of construction, such as tankers, battle cruisers, submarine
chasers, and submarines.
The handbook represents many years of collection and classifica-
tion of material, assembled primarily for the writer's everyday use.
The data have been obtained from many sources (see authorities),
not only from textbooks but very largely from technical papers and
trade literature. As it is impossible to mention in the text all the
works consulted and used, the writer wishes to make here a general
acknowledgment of his indebtedness to many other workers in the
marine field. He wishes to thank particularly the editors of Inter-
national Marine Engineering and Shipping Illustrated. Prof. H. E.
Everett kindly revised the section on Freeboard. Mr. J. C. Craven
checked Structural Details, while other friends in the trade read over
various sections: To Mr. F. G. Wickware, of D. Appleton and Co.,
he is indebted for the typographical arrangement and many sugges-
tions.
Chas. H. Hughes.
New York,
June 26, 1917.
Digiti
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CONTENTS
(See also Index)
SECTION I
WEIGHTS, MEASURES AND FORMULA
PAGB
Weights and Measures — United States and Great Britain 1
Weights and Measures — Metric System 4
Decimal Equivalents of Fractions of an Inch 5
Centimeter, Gram, Second System 6
Conversion Table — Metric Units into United States 7
Board Measure .' 8
Water, Weights of Different Units of 8
Feet Board Measure in Timber 9
Inches and Fractions in Decimals of a Foot 10
Water Conversion Table 11
Composition of Salt Water 12
Specific Gravities and Weights of Materials 13
Cubic Feet per Ton or Stowage Sines of Materials 16
Shipping Weights of Lumber 18
Weights of Miscellaneous Units of Different Products 19
Bundling Schedule of Pipe 20
Barrels, Sises of 20
Horse Powers 22
Equivalent Values of Mechanical and Electrical Units 23
Comparison of Thermometer Scales 24
Thermometers 25
Circumferences and Areas of Circles Advancing by Eights 25
Involution and Evolution 26
To Extract the Square Root of a Number 26
To Extract the Cube Root of a Number 27
Logarithms 28
Powers and Roots of Numbers 29
Circumferences and Areas of Circles 29
Geometrical Propositions 31
Circle and Ellipse, Formula pertaining to 32
Areas of Plane Figures and Surfaces of Solids 33
Volumes of Solids 36
Trigonometry— r-Trigonometric Functions 39
Oblique Triangles 41
Trigonometric Formula) 42
Natural Sines, Cosines, etc., Table of 43
Moment of Inertia, Radius of Gyration and Center of Gravity 50
Center of Gravity of a Cross Section of a Ship 50
Center of Gravity of a Water Plane 51
Properties of Sections ^ f>2
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SECTION II
STRENGTH OF MATERIALS
PAGO
Definitions— Stress, Strain, Tension, etc 70
Strength of Materials, Tables 71
Factors of Safety 73
Timber, Strength of 74
Beams — Neutral Axes, Bending Moment, Shearing Stresses, etc 75
Beam Formula 76
Beams Under Various Loading Conditions 78
Columns — Formulas for 84
' Safe Loads for H and I Columns 86
Safe Loads for Square and Round Wood Columns 87
Safe Loads for Wrought Iron Pipe, Strong and Extra Strong Columns 88
Torsional Stresses 89
Springs 90
Tubes, Pipes and Cylinders, Formulae for 90
Bursting and Collapsing Pressures of Wrought Iron Tubes 91
Ship Fittings, Strength of 91
Shearing and Tensile Strength of Bolts 93
Tests of Hooks. . .- -. 94
Tests of Shackles 95
Tests of Eye Bolts 95
Tests of Hoist Hooks 96
Tests of Turnbuckles 97
Formula for Davits 97
Stresses in Cranes, Derricks and Shear Legs 98
Rivet Heads and Points 101
Proportions of Rivets 102
Diameters of 102
Lengths for Ordering 102
Signs for Rivets 103
Shearing and Tensile Strength of Steel Rivets 104
Formula) for Riveted Joints 105
Shearing Value of Rivets and Bearing Value of Riveted Plates 107
Reduction of Diameters to Inches 108
Weight of Cone Head Rivets 109
Number of Cone Head Rivets in 100 lbs 110
SECTION III
SHIPBUILDING MATERIALS
Steel and Iron
Steel, Methods of Manufacture Ill
Carbon, Manganese, Nickel and Alloy Steels 112
Structural Steel — Lloyd's, Am. Bureau of Shipping and Am. Soc. of Testing
Materials, Requirements 114
Rivet Steel , 117
Cast Steel 118
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Iron 119
Wrought Iron . . 120
Cart Iron 120
Malleable Iron 121
Pickling Steel Plates 121
Galvanizing Fittings and Steel Plates 121
Weights of Steel Plates in Hundredths of an Inch 122
Standard Gauges— United States and Great Britain for Sheets and Plates ... 123
Diamond Checkered Plates 125
Weights of Sheets and Plates of Steel, Copper and Brass (Birmingham Wire
Gauge) 126
Weights of Sheets and Plates of Steel, Copper and Brass (American or Brown
and Sharpe Gauge) 127
Sises of Steel Plates and Heads 128
Sizes and Properties of Structural Shapes 129
Weights and Areas of Square and Round Bar/, and Circumferences of Round
Bars 143
Weights of Flat Rolled Steel Bars 149
Non-Ferrous Metals and Alloys
Copper 155
Aluminum 155
Zinc 155
Lead 155
Tin 155
Bronses — Phosphor, Admiralty, Titan, Tobin, Manganese 156
Gun Metal , 156
Brasses 156
Munts Metal 157
Naval Brass 157
Alloys 157
Wood
Sawing and Seasoning 157
Hardness of Wood, How Measured 158
Table of Relative Hardness of Soft Woods 158
Table of Relative Hardness of Hard Woods 159
Hard Wood Sizes 159
Soft Wood Sizes 160
Characteristics, Weights and Specific Gravities of Woods used in Ship-
building 160
Miscellaneous Non-Metallic Materials
Oakum 162
Caulking Cotton 162
Portland Cement 162
Insulating Materials — Magnesia, Asbestos, Cork, Hair Felt, Mineral Wool . . . 162
Steam Pipe Covering 163
Boiler Covering 163
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Cylinder Covering 164
Tests of Insulating Materials 164
Relative Value of Non-Conducting Materials 165
SECTION IV
SHIP CALCULATIONS
Lengths ,166
Breadth 166
Depth. 167
Draft 167
Displacement 168
Displacement Curve 169
Deadweight 169
Registry 169
Tonnage * ; 169
Cubic Capacity 170
Tons per Inch of Immersion 170
Coefficients — Prismatic, Block, etc 171
Wetted Surface. 172
Center of Buoyancy 172
Transverse Metacenter /. 173
Metacentric Heights 174
Moment of Inertia of a Water Plane about its Center Line 176
Displacement Sheet 177
Curves of Stability 183
Notes on Stability 189
Trim 190
Moment to Alter Trim 190
To Find the Trim by Trim Lines 192
Quantity of Water That Will Flow Into a Ship Through a Hole in Her Side. . 195
Compartment Flooded, Calculation of Trim, by Trim lines 195
Compartment Flooded, Calculation of Trim, by Mean Sinkage 196
Center of Gravity of a Vessel, Fore and Aft Position of 200
Center of Gravity of a Vessel, Vertical Position of 202
Heights of the Center of Gravity above the Base 202
Heights of the Metacenter above the Base 202
Effects of Moving Weights 203
To Find the Center of Gravity of a Vessel by Moving Weights 204
Freeboard 205
Freeboard Calculations 213
Freeboard Calculations for a Shelter Deck Steamer 218
Freeboard Notes. 220
Freeboard Markings 221
Powering Vessels 222
Approximate I. H. P. to Propel a Vessel 222
Effective Horse Power 223
Towing 223
Engine Revolutions to Drive a Vessel at a Given Speed 224
Formula for Estimating Speed of a Motor Boat 224
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Resistance 225
Law of Comparison 226
Surface Friction Constants 227
Launching 227
Launching Ways 228
Launching Calculations 229
Releasing and Checking Devices 231
Launching Data 232
Declivity of Ways and Launching Velocity 233
SECTION V
HULL CONSTRUCTION
Classification Societies and Organisations Governing Shipping 234
Types of Merchant Vessels 238
War Vessels 238
Armor 244
Armament 245
Types of War Vessels 247
Systems of Construction of Merchant Vessels. 253
Frames 255
Reverse Frames 256
Shell Plating 258
Double Bottom 261
Keelsons and Longitudinals 263
Keels. 264
Deck Plating and Coverings 264
Deck Beams I . . 265
Hatchways 266
Pillars 268
Stringers 268
Bulkheads 268
Stem and Stern Frames 272
Rudders 275
Machinery Foundations 277
Deck Erections 277
Cementing 278
Painting 279
Wood Vessels 282
Carpenter and Joiner Work 284
Interior Painting 287
Tables of Screws, Nails and Spikes 290
Structural Strength 294
Curve of Weights 294
Curve of Buoyancy 296
Curve of Loads 296
Neutral Axis and Moment of Inertia Calculations 297
Hogging and Sagging 298
Curve of Shearing Stresses 298
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Curve of Bending Moments 299
Specification Headings for Hull 300
Specification Headings for Machinery 301
Specification Headings for Equipment 301
Hull Weights, Formula for 302
Hull Weights of Vessels 303
Machinery Weights per I. h. p. 304
Engine Weights 305
Boiler Weights 306
Weights of Water Tube Boilers 308
Weights of Boilers, Engines and Auxiliaries 308
Weights of Diesel Engines 309
Data on Passenger and Cargo Steamers [reciprocating engines] 310, 311
Data on Passenger and Cargo Steamers [turbines] 312
Data on Excursion Vessels, Tugs, Lighters and Steam Yachts 314
Data on Motor Ships 316
Data on Motor Boats 317
Data on Sailing Vessels with Motors 318
Data on Schooners 319
Data on Schooners with Motors 320
Oil Carriers : 320
Lumber Steamers 327
Trawlers 327
Dredges 327
Shallow Draft Steamers 328
Tunnel Vessels 330
Fittings for Cattle and Horse Steamers 330
Prices, Costs and Estimates 331
Prices of Vessels sold in 1916 332
Estimates for Building a Motor Schooner , 334
Estimates for Operating a Motor Schooner 334
Operating Costs of Diesel Engines 335
Repair Costs of Motor Ships 336
Costs of Electric and Refrigerating Systems 337
Prices of Steam Engines and Boilers 337
Estimates, Preparing 338
Labor Costa 340
SECTION VI
MACHINERY
Steam
Definitions— British Thermal Unit, Mechanical Equivalent of Heat, Calorie.. 341
Specific, Total and Latent Heat of Steam 342
Saturated Steam 343
Superheated Steam 343
Dry Steam ' 343
Wet Steam 343
Steam Table— Properties of Saturated Steam ^Vf/^rvTv^ « • 344
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Fuels
Coal Required to Evaporate one Pound of Water 349
Coal Consumption * 349
Coal or Oil Consumptioon 350
Evaporation per Pound of Combustible 350
Heat Values of Coal 351
Calorific Value of Coal from its Chemical Analysis 351
Sises of Coals 351
Heat Values of Wood 352
Temperature of Fire 353
Air Required for Combustion of Fuel . ., 353
Oil
Crude Petroleum and its Products 353
Fuel Oil, Table of Beaum6 Gravity, Specific Gravity, etc., of. 354
Beaum6 Gravity 355
Specific Gravities and Weights of Oils 355
Definitions — Flash Point, Fire Point, Viscosity, etc 356
Oil for Boilers 356
Heat Values of CHI 366
Fuel Oils for Internal Combustion Engines 357
Lubricating Oil 358
Oil Burning Systems 360
Boilers x
Types of Boilers 363
Scotch Boilers, Proportions of 363
Scotch Boilers, Tables of 364
Locomotive Boilers 366
Leg Boilers 366
Water Tube Boilers 368
Comparison of Fire Tuoe and Water Tube Boilers 370
Boiler Horse Power 371
Boiler Horse Power Required for an Engine 371
Factor of Evaporation 373
Boiler Efficiency 374
Gallons of Water Evaporated per Minute in Boilers 375
Boiler Fittings . , 376
Safety Valve < 376
Stop Valve 377
Feed Water Connections for Scotch Boilers 377
Feed Check Valve 878
Surface and Bottom Blows 378
Steam Gauges 378
Water Gauges and Cocks 379
Boiler Circulators 379
Fusible Plugs 379
Injectors and Inspirators k 380
Hydrometer 381
Superheaters 382
Aab Ejectors , 384
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Boiler Operating 385
Firing 385
Shutting Off Boilers 386
Overhauling Boilers ^ 386
Boiling Out Boilers '. 387
Draft
Systems 389
Measurement of Draft 389
Velocity of Air under Pressure Escaping into the Atmosphere 390
Air Required 390
Blowers 391
Forced Draft Installations 392
Frictional Resistance of Stack 393
Marine Steam Engines
Types of 394
Ratio of Cylinders and Steam Expansion 394
Expansion, Cut-off and Back Pressure 395
Crank Sequences 396
Paddle Wheel Engines 397
Valves 399
Lap and Lead , 400
Valve Travel 401
Valve Mechanism 402
Setting Valves 404
Steam Pressure in a Cylinder at End of Stroke 404
Steam Pressure at Different Cut-offs 405
Cut-off and Coal or Steam Consumption 405
Indicator Cards 406
Mean Effective Pressure and I. H. P. Calculations 410
Coal Consumption per I. H. P 411
Engine Formulas— Estimated Horse Power 411
Shafting 412
Cylinders 413
Connecting Rod 413
Piston Rod 414
Pistons 414
Bearing Surfaces 414
Engine Fittings 414
.Thrust and Line Shafting Bearings 418
Engine Room Floors 419
Operating 419
Trials. 421
Propellers
Definitions — Pitch, Driving Face, Projected Area, etc 424
Slip 425
Table of Propellers 426
Formulae for Slip, Speed, Revolutions and Pitch 428
Rule for Finding Pitch of a Propeller 428
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Rule for Finding Helicoidal and Projected Area 420
Propeller Thrust 429
Propellers for Turbine Ships 429
Formula for Keys, Nuts, etc 430
Propellers for Motor Boats 431
Weights of Propellers 432
Speed Table, When Pitch, Slip and R. P.. M. Are Given 433
Paddle Wheels
Breadth of Floats, etc 436
Formulas for Slip, Speed, Revolutions and Pitch 436
Table of Paddle Wheels 437
Steam Turbines
Types of Turbines 439
Geared Turbines 442
Trials of Geared Turbines and Reciprocating Engines 443
Turbo-electric Propulsion 444
Comparative Performance of Different Systems of Propulsion 445
Efficiency 446
Steam Consumption 446-
Weights 446
Calculation of Horse Power 447
Steam per Shaft Horse Power 448
Auxiliaries 448
Steam Plant Auxiliaries
Definitions — Atmospheric Pressure, Gauge Pressure, etc 449
Thermodynamics of Condensers 449
Types of Condensers 450
Surface Condensers 452
Operating 453
Vacuum and Vacuum Gauge 454
To Find Vacuum under Working Conditions 455
Vacuum and Corresponding Steam Temperature 456
Jet Condensers 456
Cooling Water Required for Surface or Jet Condenser 457
Keel or Outboard Condensers 459
Air Pump 459
Circulating Pump , 462
Feed and Filter Tank 462
Steam Traps : 463
Feed Water Filter 464
Feed Water Heaters 465
Evaporators . • 467
Pumps, Types of 470
Reciprocating Pumps 470
Centrifugal Pumps 474
Pumps installed in a Freight Steamer 477
Installing and Operating Pumps 477
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Internal Combustion Engines
Fuels 478
Operation 479
Horse Power Formulas 480
Table of Engines (Electric Ignition) 481
Carburetors and Vaporizers 482
Starting 482
Reverse Gears 483
Lubricating Systems 484
Valves 484
Ignition Systems 486
Timers and Distributors 487
Magnetos 489
Spark Plugs 490
Motor Trouble 491
Hot Bulb Engines 492
Diesel Engines 495
Comparison of Diesel Engines, Steam Engines and Turbines 495
General Features of Diesel Engines 496
Operation 498
Types of Diesel Engines 501
Diesel Engine Installations 506
Piping, Tubing, Valves and Fittings
Trade Terms 507
Tables of Standard, Extra Strong, and Double Extra Strong Wrought Iron
Pipe 508, 509
Boiler Tubes 510, 511, 512
Copper Tubes 513
Brass and Copper Tubes 514
Brass and Copper Pipe 518
Formula for Working Pressure 518
Copper Tubes 519
Bending Pipes and Tubes 519
Flow of Water through Pipes 520
Comparative Areas of Pipes 521
Flanges 522
Bolt and Pipe Threads 524
Gaskets 526
Nipples and Couplings 526
Unions 526
Materials for Piping Systems ,. 527
Valves, Cocks and Fittings 528
SECTION VII
ELECTRICITY
Definitions — Ohm, Ampere, Volt, Coulomb, etc 531
Voltage 532
Wires. Calculation of Size of 533
Tables of Sizes of Wires 534,535, 536, 537
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Diameters by Different Wire Gauges 538
Wiring Systems ! 530
Conduits 541
Switchboards and Equipment 543
Determination of Output 543
Laying Out Electric Installations 544
Wiring of a Steamer 547
Wiring of a Motor Boat 550
Wiring of Gasoline Engines 551
Incandescent Lamps 552
Searchlights 553
Primary Batteries 554
Storage Batteries 554
Grouping of Cells 557
Generating Sets 557
Windings of Generators J 558
Engine Horse Power 558
Tables of Direct Connected Sets 559
Operating Notes 560
Electric Motors, Windings of 561
Formula for Horse Power of Motor 562
Weights of Motors. 563
Current Taken by Motors 564
Motors for Ship Work. 564
Motor Starting and Controlling Devices 565
SECTION VIII
HEATING, VENTILATION, REFRIGERATION, DRAINAGE, PLUMBING
AND FIRE EXTINGUISHING SYSTEMS
Heat Passing Through a Ship's Side or Bulkhead 567
Heating Systems 568
Heating by Steam 568
Steam Heating Installations 568
Sizes of Radiators 560
Square Feet of Radiation for a Room 570
Heating Surfaces of Pipes 571
Heating by Thermotanks 571
Heating by Electricity 573
Heating by Special Systems 574
Ventilation
Fresh Air Required. . » 675
Air Pressure 576
Systems — Plenum and Exhaust 576
Ventilation of Oil Carriers 578
Ventilation of Engine Rooms 579
Ventilators 579
Fans, Types of 580
Horse Power Required to Drive a Fan 682
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Ducts 582
Data on the Escape of Air into the Atmosphere . . . . ? 583
Duct Areas 584
Laying Out Ventilating Systems 584
Loss of Pressure by Friction of Air in Pipes 585
Refrigeration
Keeping Perishable Products 587
Insulating Materials 587
Cold Storage Temperatures 588
Compression System 591
Brine Circulating 593
Refrigerants — Ammonia and Carbon Dioxide 594
Different Makes of Machines 594
Cooling by Air 595
Pipe, Valves and Fittings 596
Linear Feet of Pipe Required 596
Capacity of Ammonia Compressors 597
Refrigeration Required for Cold Storage Rooms 598
Refrigeration Required for Stored Products 599
Specific Heat and Latent Heat of Food Products 600
Horse Power Required for Compressors . 60C
Operating Notes 600
Drainage
Systems 601
Main Drain 602
Auxiliary Drain 603
U. S. Steamboat-Inspection and Lloyd's Requirements 603
Plumbing
Fixtures 606
Waste Lines 609
Fresh Water Service 609
Fire Extinguishing and Alarm Systems
General Requirements 610
Fire Main (Water) 611
Sises of Water Streams 612
Fire Main (Steam) 612
Sulphur Dioxide System 613
Sprinkler Systems 614
Fire Alarms 614
SECTION IX
SHIP EQUIPMENT
Steering Gears 615
Steam Steering Gears 615
Electric Steering Gears 616
Arrangements 617
Installations 618
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Transmission 620
Power Required to Turn a Rudder 623
Pressure on Rudder 623
Steering Chain and Rod 624
Windlasses — Steam and Electric 624
Table of Steam Windlasses 625
Winches or Hoisting Engines — Steam and Electric 626
Tables of Winches 627
Power Required to Raise a Load 628
Rope Capacity of a Drum 628
Capstans and Gypsy Capstans) — Steam and Electric 630
Tables of Capstans 630
Towing Machines 631
Rope, Trade Terms 632
Hoisting Speeds 632
Knots and Hitches , 633
Tension in Hoisting Rope 634
Kinds of Rope, Materials and Strands 634
Weight and Strength of Manila Rope 636
Weight and Strength of Hemp Clad Wire Rope 637
Weight and Strength of Flattened Strand Hoisting Rope 638
Table Comparing Manila and Hemp Clad Wire Rope 640
How to Measure Wire Rope 640
Weight and Strength of Cast Steel Wire Rope 641
Weight and Strength of Steel Mooring Lines 642
Formulse for Size and Weight of Rope 642
Weight and Strength of Yacht Rigging and Guy Ropes 643
Weight and Strength of Galvanized Steel Hawsers 644
Weight and Strength of Galvanized Ships' Rigging and Guy Ropes 645
Weight and Strength of Galvanized Steel Hawsers 646
Length of Rope Required for Splices 646
Blocks, Types of 646
Wood Blocks for Manila Rope 648
Steel Blocks for Wire Rope 648
Working Loads for Blocks 648
Tackles, Types of 650
Power Gained with Tackles 652
Chain 655
Pitch, Breaking and Working Strains of Chain 656
Anchors, Types of 657
Anchors for Yachts and Motor Boats 657
Anchors for Steam Vessels 658
Anchors for Sailing Vessels 659
Anchor Cranes 660
Life-Saving Equipment — U. S. Steamboat-Inspection Requirements 663
Life-Saving Equipment, Abstracts from Seamen's Bill 665
Capacities of Lifeboats 669
Lundin Lifeboats 670
Engelhardt Collapsible Lifeboats 671
Life Rafts : 672
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Life Preservers 672
Buoys 673
Boats Carried by War Vessels •. , 673
Boat Davits 673
Rotating Davits 673
Pivoted Davits 676
Quadrant Davits 676
Heel of a Vessel When Lowering a Boat 678
Rigs of Vessels 679
Wireless Equipment 680
Storm Oil • 681
Line-carrying Guns and Rockets 682
SECTION X
SHIP OPERATING
Loading and Stowing of Cargoes
General Considerations — Stability, Winging Out Weights, etc 683
Oil Cargoes— Bulk 684
Stowage of Oil in Barrels .-. . . 685
Stowage of Oil in Cases 686
Grain Cargoes 688
Settling of Grain and Angle of Repose 688
Rules of N. Y. Board of Underwriters 688
Board of Trade Requirements 692
Coal Cargoes 693
Effect of Using Bunker Coal 693
Rules of N. Y. Board of Underwriters 693
Lumber Cargoes 694
Regulations for Carrying Dangerous Articles 695
MACHINERY OPERATING (see Index)
Maintenance
When Surveys Are to Be Made 696
Hull — Shell Plating Working 698
Decks Leaking 698
Removing of Rubbish from Bilges 698
Galvanic Action 698
Corrosion in Double Bottom 699
Sea Valves and Outboard Bearings 699
Docking. .' 699
Painting (see Index)
Machinery, Care of 700
Surveys 700
Taking Indicator Cards 701
Care of Boilers 701
Log to Be Kept by Engineer 702
Digitized
by Google
Table of Contents xxi
PAOB
; Ship Chartering 1
Trip Charters .• 703
Contracts for the Movement of Freight 704
Time Charter 704
Charter Forms 704
Preamble Clause 707
Delivery 707
Redelivery 708
Trading Limits and Insurance Warranties 708
Speed amd Consumption -. 708
Berth Terms 709
Cotton Rates 709
Abbreviations 709
Marine Insurance
Insurable Value 711
Ship 711
Freight. : 711
Goods 711
Policies, Paragraphs in ." 711
Kinds of Policies. 713
General Average 713
Particular Average 714
River Plate, Clause 715
Protection and Indemnity Clause 715
Collision or Running Down Clause 715
Inchmaree Clause 715
Export and Shipping Terms
Abbreviations and Terms 716
Authorities Quoted "*. 718
Index 721
Digiti
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j
ABBREVIATIONS AND SYMBOLS
Weights and Measures (U. S. and English)
oz.
ounce
lb.
pound
hundredweight
cwt.
in.
inch
//
inch
ft.
foot
/
foot
yd.
yard
fathom
fath.
mi.
mile
kt.
knot .
pt.
pint
m.
Weight!
meter
g.
gram
<
>
V
a"
a*
a*
an
%
X
log
sin
cos
tan
cotan
qt
gal.
ft
sq.
D'
cu.
Ft. B.M
C.G.S.
bbl.
quart
gallon
peck
bushel
square
square foot
cubic
feet board measure
Centimeter. Gram,
Second System
barrel
Weights and Measures (Metric)
equals
less than
more than
sum
square root of the
quantity under the
sign
cube root of the quan-
tity under the sign
square root of a
square of a
nth root of a
a raised to the nth
power
percent
3.14159
logarithm
sine
cosine
tangent
cotangent
1.
liter
See metric system for prefixes.
neous
sec
secant
cosec
cosecant
F. or
Fahr.
Fahrenheit
C
Centigrade
R
Reaumer
Be
Beauine*
I
moment of inertia
S
modulus of section
r
radius of gyration
Sp.gr.
specific gravity
g
acceleration due to
gravity = 32.16 ft.
per sec.
B.t.u.
British thermal unit
S.W.G.
Stubs Wire Gauge
B.w.g.
B&S
Birmingham wire gauge
Brown & Sharpe
A.W.G.
American Wire Gauge
I.W.G.
Imperial Wire Gauge
N.B.S.
New British Standard
xxm
Digiti
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XXIV
ABBREVIATIONS AND SYMBOLS
Naval Architecture
F.P.
forward perpendicular
after perpendicular
C.G.
center of gravity
A.P.
B.M.
distance between cen-
Bet.
ter of buoyancy and
perps
. length between perpen-
metacenter
diculars
B.G.
distance between cen-
L.O.A.
length over all
ter of buoyancy and
B.
beam molded
center of gravity
D.
depth molded
G.M.
distance between cen-
**
midship section
ter of gravity and
d.w.
dead weight
metacenter
W.L. or
G.Z.
arm of righting couple
w.L
water line
Bkhd.
bulkhead
C.B.
center of buoyancy
B.L.
base line
M.
metacenter
See Rivets and Riveting
Machinery
h.p.
horsepower
t.h.p.
thrust horse power
l.h.p.
indicated horse power
m.e.p.
mean effective pres-
e.h.p.
effective horse power
sure
b.h.p.
brake horse power
r.p.m.
revolutions per minute
n.h.p.
nominal horse power
G.S.
grate surface
heating surface
s.h.p.
shaft horse power
H.S.
Electricity
d.c.
direct current
Q.
coulomb
a.c.
alternating current
J.
Joule
C.
amperes
W.
watt
E.
volts
Kw.
kilowatt
R.
Ohms
c.p.
candle power
e.m.f.
electromotive force
cir. mils, circular mils
Ship Chartering abbreviations. — See section on Ship Chartering.
Marine Insurance abbreviations. — See section on Marine Insur-
ance.
Shipping and Export abbreviations. — See section on Shipping and
Export Terms.
Digiti
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HANDBOOK OF SHIP CALCULATIONS,
CONSTRUCTION AND OPERATION
Digiti
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Digiti
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Handbook of
Ship Calculations, Construction
and Operation
SECTION I
WEIGHTS, MEASURES AND FORMULAE
WEIGHTS AND MEASURES
Troy Weight
24 grains = 1 pennyweight 12 ounces = 1 pound
20 pwts. = 1 ounce
Used for weighing gold, silver and jewels.
Apothecaries' Weight
20 grains = 1 scruple 8 drams = 1 ounce
3 scruples = 1 dram 12 ounces = 1 pound
The ounce and pound in this are the same as in Troy weight.
Avoirdupois Weight
27.344 grains — 1 dram 2000 pounds — 1 short ton
16 drams = 1 ounce 2240 pounds = 1 long ton
16 ounces = 1 pound
Shipping Weight
16 ounces — 1 pound (lb.)
28 pounds — 1 quarter (qr).
4 quarters or 112 pounds — 1 hundredweight (cwt.)
20 hundredweight or \ . , ^ x
2240pounds J" " * ton ™
1
2 WEIGHTS AND MEASURES
•-*'■* Shipping Measure
1 register ton = 100 cubic feet
1 United States shipping ton = 40 cubic feet or o2.14 United States
bushels or 31.16 Imperial bushels
1 British shipping ton = 42 cubic feet or 32.72 Imperial
bushels or 33.75 United States
bushels
Linear Measure (Land)
12 inches = 1 foot 40 rods = 1 furlong
3 feet = 1 yard 8 furlongs 1 , ., , . . . N
5* yards = 1 rod or 5280 feetj = 1 nule (8tatute)
Other units are: 4 inches = 1 hand; 9 inches = 1 span; 1000
mils = 1 inch; 7.92 inches = 1 link: 100 links or 66 feet or 4 poles
= 1 chain; 10 chains — 1 furlong.
Mariner's Measure
6 feet = 1 fathom 6080 feet ■» 1 nautical mile (knot)
120 fathoms = 1 cable length 3 knots = 1 league
1 cable length - 120 fathoms = 960 spans - 720 feet - 219.457
meters.
1 international nautical mile = -fa degree at meridian = .999326
U. S. nautical miles = 1852 meters = 6076.10 ft.
1 U. S. nautical mile is the length of one minute of arc of a great
circle of a sphere whose surface equals that of the earth. Thus
1 U. S. nautical mile » 1.15155 statute miles = 6080.20 ft. =
1853.25 meters.
1 British nautical mile = 1.15152 statute miles = 6080 feet =
1853.19 meters. The knot generally adopted is the one of 6080 feet.
Square Measure
144 square inches = 1 square foot 40 square rods = 1 rood
9 square feet = 1 square yard 4 roods = 1 acre
30 J4 square yards = 1 square rod 640 acres = 1 square mile
Time Measure
60 seconds = 1 minute 24 hours — 1 day
60 minutes — 1 hour 7 days = 1 week
28, 29, 30 or 31 days - 1 calendar month (30 days = 1 month
in computing interest)
365 days * 1 year 366 days = 1 leap year
Digitized by VJiOOQLC
MEASURES 3
Circular Measure
60 seconds ~ 1 minute 90 degrees «= 1 quadrant
60 minutes = 1 degree 360 degrees - 1 circumference
Instead of an angle being given in degrees it can be given in
radians, one radian being equal to the arc of a circle whose length
is the radius. Thus if R denotes the radius, the circumference
of the circle 2 w R, then the circular measure of 90° = — — W~~ ~
^; similarly the circular measure of 180° is r, 60° -£ , etc.
An angle expressed in degrees may be reduced to circular measure
by finding its ratio to 180° and multiplying the result by x.
Hence the circular measure of 115° is — ^ — = .63 t
An angle expressed in circular measure may be reduced to de-
grees by multiplying by 180 and dividing by ir, or by substituting
180 for x. As \£ = ~ X 180 - 84°.
lo 15
The angle whose subtending arc is equal to the radius, or the
180°
unit of circular measure reduced to degrees is = 57.2958.
Therefore an angle expressed in circular measure may be reduced
2 2
to degrees by multiplying by 57.2958. Thus the angle - « ^
o o .
X 57.2958 = 38.1972°.
Dry Measure
2 pints = 1 quart 4 pecks = 1 bushel
8 quarts » 1 peck 36 bushels = 1 chaldron
One United States struck bushel contains 2150.42 cu. ins. or
1.244 cu. ft. By law its dimensions are those of a cylinder 18 }4
ins. diameter by 8 ins. high. A heaped bushel is equal to 1 % struck .
bushels the cone being 6 ins. high. A dry gallon contains 268.8
cu. ins. and is H of a struck bushel. One U. S. struck bushel
may be taken as approximately 1J£ cu. ft., or 1 cu. ft. as f of a
busheL
The British bushel contains 2218.19 cu. ins. or 1.2837 cu. ft.
or 1.032 U. S. bushels.
Digiti
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4 WEIGHTS AND MEASURES
Liquid Measure =
4 gills = 1 pint 31H gallons — 1 barrel ~~
2 pints = 1 quart 2 barrels or 63 gallons =
4 quarts = 1 gallon 1 hogshead
One United States gallon contains 231 cu. ins. or .134 cu. ft., or '
1 cu. ft. contains 7.481 gallons. •
The British Imperial gallon both liquid and dry contains v277. 27 a
cu. ins. or .160 cu. ft., and is equivalent to the volume of 10 lb. :
of pure water at 62° F. To convert British to U. S. liquid gallons
multiply by 1.2. To convert U. S. into British divide by 1.2. "
Metric System
The fundamental unit of the metric system is the meter, the
unit of length, which is one ten-millionth of the distance from the
pole to the equator or 39.3701 ins. From the meter the units of *
capacity (liter) and of weight (gram) are derived with subdivisions '
of 10 or multiples of 10, the following prefixes being used: milli = ,
j^j, centi « ^, deci = ^, deca = 10, hecto - 100, kilo =
1000, myrie = 10000. Thus a millimeter is ^^r of a meter, and
so on. The units of meter, liter and gram are simply related, as
for all practical purposes 1 cubic decimeter = 1 liter and 1 liter of
water weighs 1 kilogram at 4° C.
The metric system is specified by law in Argentina, Austria,
Belgium, Bolivia, Brazil, Bulgaria, Chile, Colombia, Denmark,
Finland, France, Germany, Holland, Hungary, Italy, Luxemburg,
Mexico, Montenegro, Norway, Peru, Portugal, Roumania, Servia,
Siam, Spain, Sweden, Turkey and Uruguay.
Linear Measure
10 millimeters = 1 centimeter = .394 inches
10 centimeters = 1 decimeter «= 3.937 inches
10 decimeters = 1 meter =* 39 37 inches or 3.281 feet
10 meters = 1 decameter = 32.809 feet
10 decameters = 1 hectometer = 328.09 feet
10 hectometers = 1 kilometer = 3280.9 feet
Surfaces
surfaces
100 square millimeters = 1 square centimeter = .155 square inches
100 square centimeters = 1 square decimeter = 15.5 square inches
100 square decimeters = 1 square meter — 10.764 square feet
Digitized
by vjOOQLC
Decimal Equivalents op Fractions op an Inch, and Milli-
meter-Inch Conversion Table
Fract.
Dec.
Mm.
Fract
Dec.
Mm. ||Mm.
Dec. Inch
Mm.
Dec. Inch
* ...
.015625
.397
a
.515625
13.1
1
2
.039370
.078740
51
52
2.007892"
2.047262
A....
.03125
.79
ii....
.53125
13.49
3
.118110
53
2.086632
A---
.046875
1.19
a....
.546875
13.89
4
5
.157480
.196850
54
55
2.126002
2.165372
A....
.0625
1.59
a....
.5625
14.29
6
.236220
56
2.204742
A ....
.078125
1.98
ii....
.578125
14.68
7
8
.275509
.314960
57
58
2.244112
2.283482
A-...
.09375
2.38
H-...
.59375
15.08
9
.354330
59
2.322852
A---
.109375
2.77
«....
.609375
15.48
10
11
.393704
.433074
60
61
2.362226
2.401596
1....
.125
3.17
I....
.625
15.87
12
13
.472444
.511814
62
63
2.440966
2.480336
A--
.140625
3.57
ii-..-
.640625
16.27
14
.551184
64
2.519706
A.--
.15625
3.97
H-...
.65625
16.7
15
16
.590554
.629924
65
66
2.559076
2.598446
»....
.171875
4.37
a....
.671875
17.06
17
.669294
67
2.637816
A....
.1875
4.76
«... .
.6875
17.46
18
19
.708664
.748034
68
69
2.677186
2.716566
if...-
.203125
5.16
a....
.703125
17.86
20
21
.787409
.826779
70
71
2.755930
2.795300
A-.-.
.21875
5.56
Ii....
.71875
18.26
22
.866149
72
2.834670
if...-
.234375
5.95
«....
.734375
18.65
23
24
.905519
.944889
73
74
2.874040
2.913410
*....
.25
6.35
!....
.75
19.05
25
.984259
75
2.952780
«....
.265625
6.75
a....
.765625
19.45
26
27
1.023629
1.062999
76
77
2.992150
3.031520
A--.-
.28125
7.14
H....
.78125
19.84
28
1.102369
78
3.070890
«....
.296875
7.54
a....
.796875
20.24
29
30
1.141739
1.181113
79
80
3.110260
3.149635
A-.-
.3125
7.94
ii...
.8125
20.64
31
32
1.220483
1.259853
81
82
3.189005
3.228375
«-...
.328125
8.33
a..--
.828125
21.03
33
1.299223
83
3.267745
«...
.34375
8.73
ii....
.84375
21.43
34
35
1.338593
1.377963
84
85
3.307115
3.306485
u....
.359375
9.13
a..-.
.859375
21.83
36
1.417333
86
3.385855
1....
.375
9.52
i....
.875
22.22
37
38
1.456703
1.496073
87
88
3.425225
3.464595
it....
.390625
9.92
a....
.890625
22.62
39
40
1.535443
1.574817
89
90
3.503965
3.543339
H-...
.40625
10.32
ii....
.90625
23.02
41
1.614187
91
3.582709
11....
.421875
10.72
»....
.921875
23.41
42
43
1.653557
1.692927
92
93
3.622079
3.661449
.7
.4375
11.11
it...
.9375
23.81
44
1.732297
94
3.700819
If...-
.453125
11.51
a...
.953125
24.21
45
46
1.771667
1.811037
95
96
3.740189
3.779559
M-...
.46875
11.91
ii...
.96875
24.61
47
1.850407
97
3.818929
H-...
.484375
12.30
a....
.984375
25.
48
49
1.889777
1.929147
98
99
3.858299
3.897669
J....
.5
12.7
i
25.4001
50
1.908522
100 3.937043
JvJ\Jvl^
WEIGHTS AND MEASURES
Volume and Capacity
.61 cubic inches
6.10 cubic inches
61.02 cubic inches
.353 cubic feet
3.53 cubic feet
35.31 cubic feet
10 milliliters = 1 centiliter
10 centiliters = 1 deciliter
10 deciliters = 1 liter
10 liters = 1 decaliter
10 decaliters = 1 hectoliter
10 hectoliters = 1 kiloliter
A liter is equal to the volume occupied by 1 cubic decimeter of
water at 4° C.
Weight
10 milligrams = 1 centigram = .154 grains
10 centigrams = 1 decigram = 1.54 grains
10 decigrams = 1 gram = 15.43 grains
10 grams = 1 decagram = 154.3 grains
10 decagrams = 1 hectogram = .220 pound avoirdupois
10 hectograms = 1 kilogram = 2.204 pound avoirdupois
1000 kilograms = 1 metric ton = 2204.621 pound avoirdupois
One gram is the weight of 1 cu. cm. of pure distilled water at a
temperature of 39.2° F., or 4° C; a kilogram is the weight of 1
liter (1 cubic decimeter) of water; a metric ton is the weight of 1
cubic meter of water.
Centimeter, Gram, Second, or Absolute System op Physical
Measurement
Unit of space or distance = 1 centimeter
Unit of mass = 1 gram
Unit of time = 1 second
Unit of velocity = -? —
Unit of acceleration
= 1 centimeter in 1 second
change of 1 unit of velocity
in 1 second
Acceleration due to gravity at Paris = 981 centimeters in 1 second.
= 1 dyne! = ggj gramme
.0022046
981
lb. =
Unit of force
.000002247 lb.
A dyne is that force which acting on a mass of one gram during
one second will give it a velocity of one centimeter per second.
The weight of one gram in latitude 40° to 45° is about 980 dynes,
at the equator 973 dynes and at the poles 984 dynes. Taking
the value of g, the acceleration due to gravity in British measures
at 32.185 ft. per second at Paris, and the meter as 39.37 ins., then
32.185 X 12 nQ1 ,
1 gram = ^^ = 981 dynes.
.3937
Digiti
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METRIC CONVERSION TABLE
Metric Conversion Table
Reading from Left to Right and Vice Versa
Millimeters
X
.03937
=
Inches
Millimeters
=»
25.400
X
Inches
Meters
X
3.2809
=
Feet
Meters
=
.3048
.X
Feet
Kilometers
X
.621377
=
Miles
Kilometers
=a
1.6093
X
Miles
Square centimeters
X
.15500
=
Square inches
Square centimeters
=
6.4515
X
Square inches
Square meters
X
10.76410
=
Square feet
Square meters
=
.09290
X
Square feet
Square kilometers
X
247.1098
»
Acres
Square kilometers
=
.00405
X
Acres
Hectares
X
2.471
=
Acres
Hectares
=5
.4047
X
Acres
Cubic centimeters
X
.061025
=
Cubic inches
Cubic centimeters
=
16.3866
X
Cubic inches
Cubic meters
X
35.3156
=
Cubic feet
Cubic meters
=
.02832
X
Cubic feet
Cubic meters
X
1.308
=
Cubic yards
Cubic meters
=
.765
X
Cubic yards
Liters
X
61.023 .
=
Cubic inches
Liters
=
.01639
X
Cubic inches
Liters
X
.26418
=
U. S. Gallons
Liters
=
3.7854
X
U. S. Gallons
Grams
X
15.4324
=
Grains
Grams ,
—
.0648
X
Grains
Grams
X
.03527
=
Ounces avoirdupois
Grams
—
28.3495
X
Ounces avoirdupois
Kilograms
X
2.2046
=
Pounds
Kilograms
=
.4536
X
Pounds
Kilog's per sq.
centim.
X
14.2231
=
Lbs. per sq. inch
Kilog's per sq.
centim.
=
.0703
X
Lbs. per sq. inch
Kilog's per cu.
meter
X
.06243
=
Lbs. per cu. ft.
Kilog's per cu.
meter
—
16.01890
X
Lbs. per cu. ft.
Metric tons (1000 Kg.)
X
1.1023
=
Tons (2000 lb.)
Metric tons (1000 Kg.)
=
0.9072
X
Tons (2000 lb.)
Kilowatts
X
1.3405
=
Horse power
Kilowatts
—
.746
X
Horse power
Calories
X
3.9683
=
B. thermal units
Calories
=»
.2520
X
B. thermal units
Example. 25.4 millimeters X .
03937 = 1 inch.
1 inch X 25.4 - 25.4 milli-
meters.
Digitized by VjiOOQIC
8 WEIGHTS AND MEASURES
Unit of work - 1 erg » 1 dyne-centimeter » .00000007373 ft. lb.
Unit of power = 1 watt — 10,000,000 ergs per second
- .7373 ft. lb. per second
■W-7i6hp--00134hP-
Centimeter, Gram, Second (CGS) unit of magnetism — the
quantity which attracts' or repels an equal quantity at a distance of
one centimeter with a force of one dyne.
CGS unit of electric current = the current which, flowing
through a length of one centimeter of wire, acts with a force of
one dyne upon a unit of magnetism distant one centimeter from
every point of the wire. The ampere, the commercial unit of
current, is one-tenth of the CGS unit.
Board Measure
To find the number of feet board measure in a stick of timber,
multiply the length in feet, by the breadth in feet, by the thickness
in inches.
Example. Find the board measure of a piece of timber 20 ft. long, 2 ft. wide by
2 ina. thick.
20 ft. X 2 ft. X 2 ins. - 80 feet board measure.
To convert board feet into cubic feet, divide the board feet by 12.
To convert board feet into tons, divide the board feet by 12,
and multiply the quotient by the weight of the timber per cubic
foot, thus giving the weight in pounds. Divide the weight in
pounds by 2240 to get it into long or shipping tons, or by 2000 to
get into short tons.
Example. A schooner has 1,000,000 feet board measure, of yellow pine on
board. What is the weight of her load in shipping tons?
1,000,000 «, 83t333 cu- ft> Yellow pine weighs 38 lb. per cu. ft.
12 38
3,166,654 lb. = 1415 tons nearly.
Water
One cubic foot of fresh water weighs 62.42 lb. at its maximum density
39.1° F.
One cubic foot of salt water weighs 64 lb.
35.88 cubic feet of fresh water weighs one ton (2240 lb.)
35 cubic feet of salt water weighs one ton
One cubic foot of water (fresh or salt) = 7.48 gallons (U. S.)
One gallon (U. S.) of fresh water weighs 8.33 lb.
One gallon (U. S.) of salt water weighs 8.58 lb.
One cubic foot of ice (fresh) weighs 56 lbs., specific gravity .9.
ioogle
BOARD MEASURE
Feet Board Measure in Different Sizes of Timber*
Siae in Inches
Length in Feet
10 12 14
16
18 20 22 24 26 28
30 32
2x4.
2x6.
2x8.
2 x 10.
2 x 12.
2 x 14.
2 x 16.
2*x 12.
2*x 14.
2*x 16.
3x6.
3x8.
3 x 10.
3 x 12.
3 x 14.
3 x 16.
4x4.
4x6.
4
4
4
4
6 x
6 x
6 x
6 x
6 x
6 x
8 x
8 x
8 x
8 x
10 x
10 x
10 x 14.
10 x 16.
12 x 12.
12 x 14.
12 x 16.
14 x 14.
14 x 16.
8.
10.
12.
14.
6.
8.
10.
12.
14.
16.
8.
10.
12.
14.
10.
12.
61
10
13*
16|
20
23*
26}
25
29*
33*
15
20
25
30
35
40
13*
20
26*
33*
40
46*
30
40
50
60
70
80
53*
66*
80
03*
83*
100
116*
133*
120
140
160
163*
186}
8
12
16
20
24
28
32
30
35
40
18
24
30
36
42
48
16
24
32
40
48
56
36
48
60
72
84
96
64
80
96
112
100
120
140
160
144
168
192
196
224
9*
14
18}
23*
28
32}
37*
35
40}
46}
21
28
35
42
49
56
18}
28
37*
46}
56
65*
42
56
70
84
98
112
74}
93*
112
130}
116}
140
163*
186}
168
196
224
228}
261*
10}
16
21*
26}
32
37*
42}
40
46}
53*
24
32
40
48
56
64
21*
32
42}
63*
64
74}
48
64
80
96
12
128
85*
106}
128
149*
133*
160
186}
213*
192
224
256
261*
298}
12
18
24
30
36
42
48
45
52*
60
27
36
45
54
63
72
24
36
48
60
72
84
54
72
90
108
126
144
96
120
144
168
150
180
210
240
216
252
288
294
336
13*
20
26}
33*
40
46}
63*
50
68*
66}
30
40
50
60
70
80
26}
40
63*
66}
80
93*
60
80
100
120
140
160
106}
133*
160
186}
166}
200
233*
266}
240
280
320
326}
373*
14}
22
29*
36}
44
61*
68}
55
64*
73*
33
44
55
66
77
44
58}
73*
88
102}
66
88
110
132
154
176
17*
146}
176
205*
183*
220
256}
293*
264
308
352
359*
410}
16
24
32
40
48
56
64
60
70
80
36
48
60
72
84
96
32
48
64
80
96
112
72
96
120
144
168
192
128
160
192
224
200
240
280
320
288
336
384
392
448
17*
26
34}
43*
52
60}
69*
65
751
86}
39
62
65
78
91
104
34}
52
86}
104
121*
78
104
130
156
182
208
138}
173*
208
242}
216}
260
303*
346}
312
364
416
424}
485*
18}
28
37*
46}
56
65*
74}
70
81}
93*
42
56
70
84
112
37*
56
74}
93*
112
130}
84
112
140
168
196
224
149*
186}
224
261*
233*
280
326}
373*
336
392
448
457*
622}
20
30
40
50
60
70
80
75
87*
100
45
60
75
90
105
120
40
60
80
100
120
140
90
120
150
180
210
240
160
200
240
280
250
300
350
400
360
420
480
490
560
21*
32
42}.
53*
64
74}
85*
80
93*
106}
48
64
80
96
112
128
42}
64
85*
106}
128
149*
96
128
160
192
224
256
170}
213*
256
298}
266}
320
373*
426}
384
448
512
522}
597*
Thus a stick of timber 2 ins. X 4 ins. X 12 ft. long contains
8 ft. board measure. Board measure is often abbreviated B. M.
* From Mechanical Engineer's Handbook. W. Kent.
Digitized by VJiOOQLC
Inches
and Fractions
in Decimals op
a Foot
Parts of
Foot in
Inches
and
Fractions
Decimal
of a
Foot
Parts of
Foot in
Inches
and
Fractions
Decimal
of a
Foot
Parts of
Foot in
Inches
and
Fractions
Decimal
of a
Foot
Parts of
Foot in
Inches
and
Fractions
Decimal
of a
Foot
A
.00520
3A
.25520
6A
.50520
9A
.75520
y%
.01040
3H
.26040
m
.51040
W%
.76040
A
.01562
3A
.26562
6A
.51562
9A
.76562
M
.02080
W*
.27080
6M
.52080
9H
.77080
A
.02600
3A
.27600
6A
.52600
9A
.77600
H
.03125
2K
.28125
*K
.53125
9K
.78125
A
.03640
3A
.28650
CA
.53640
9A
.78650
H
.04170
3H
.29170
QH
.54170
9H
.79170
A
.04687
3A
.29687
6A
.54687
9A
.79687
%
.05210
W%
.30210
&A
.55210
w%
.80210
tt
.05730
3H
.30730
6tt
.55730
9H
.80730
&
.06250
3M
.31250
6M
.56250
9H
.81250
tt
.06770
3tf
.31770
6H
.56770
9tt
.81770
7A
.07290
3%
.32290
&/%
.57290
97A
.82290
tt
.07812
3tf
.32812
6tf
.57812
9H
.82812
l
.08330
4
.33333
7
.58330.
10
.83333
1A
.08850
4A
.33850
7A
.58850
10 A
.83850
1H
.09375
4M
.34375
7H
.59375
ioh
.84375
1A
.09900
4A
.34900
7A
.59900
ioa
.84900
l«
.10420
4K
.35420
7H
.60420
10M
.85420
1A
.10937
4 A
.35937
7A
.60937
10 A
.85937
1H
.11460
*K
.36460
7H
.61460
10H
.86460
1A
.11980
4A
.36980
7A
.61980
10A
.86980
1H
.12500
4^
.37500
7H
.62500
10H
.87500
1A
. 13020
4A
.38020
7A
.63020
ioa
.88020
1H
. 13540
*K
.38540
W%
.63540
10«
.88540
ltt
. 14062
4tt
.39062
7H
.64062
10 H
.89062
1M
.14580
4%
.39580
7H
.64580
ioh
.89580
ltt
.15100
4tt
.40100
7tt
.65100
10 tt
.90100
i«
. 15625
. 4K
.40625
7J*
.65625
10H
.90625
1H
.16150
4tt
.41140
7tt
.66150
10 »
.91150
2
. 16670
5
.41670
8
.66670
n
.91670
2A
.17187
5A
.42187
8A
.67187
HA
.92187
2H
. 17710
5ys
.42710.
8H
.67710
UH
.92710
2A
. 18230
5A
.43230
8A
.68230
HA
.93230
2tf
.18750
5M
.43750
8^
.68750
HM
.93750
2A
. 19270
5A
.44270
8A
.69270
HA
.94270
2^
. 19790
5%
.44790
W%
.69790
UK
.94790
2A
.20312
5A
.45312
8A
.70312
HA
.95312
2*4
.20830
5H
.45830
8J4
.70830
HH
.95830
2A
.21350
5A
.46350
8A
.71350
HA
.96350
2^
.21875
5^
.46875
8$*
.71875
UK
.96875
2tt
.22400
5tt
.47400
8tt
.72400
litt
.97400
2H
.22920
5«
.47920
SH
.72920
nx
.97920
2tt
.23437
5tt
.48437
8tt
.73437
litt
.98437
2Ji
.23950
w%
.48960
8^
.73960
uy8
.98960
2tt
.24480
5tt
.49480
8tt
.74480
ntt
.99480
3
.25000
6
.50000
9
.75000
12
1.00000
10
Digitized by VJ^J^VLV^
FRESH WATER
11
Fresh Water
One Imperial gallon" = 277.27
One Imperial gallon = . 16
One Imperial gallon ' = 10.00
One Imperial gallon = 4 . 54
One Imperial gallon = 1 . 20
One U. S. gallon = 231
One U. S. gallon = . 134
One U. S. gallon = 8.33
One U. S. gallon = .83
One U. S. gallon = 3.8
One pound of water = 27 . 74
One pound oi water = . 083
One pound of water = . 10
One cwt. of water = 11.2
One cwt. of water = 13 . 44
One cwt. of water = 1 . 79
One ton of water = 35 . 88
One ton of water =223.60
One ton of water = 268.38
One ton of water = 1000
One ton of water = 1
One cubic inch of water = .036
One cubic inch of water = .0036
One cubic inch of water = .0043
One cubic foot of water = .027
One cubic foot of water ■» . 55
One cubic foot of water • = 62 . 42
One cubic foot of water = 6.23
One cubic foot of water = 7 . 48
One cubic foot of water = 28.31
One cubic foot of water = .028
One liter of water = .22
One liter of water = . 264
One liter of water = 61
One liter of water *» .0354
One cubic meter of water = 220
One cubic meter of water' = 264
One cubic meter of water = 1 . 308
One cubic meter of water = 35 . 31
One cubic meter of water = 61024
One cubic meter of water =* 1000
One cubic meter of water = 1
One cubic meter of water = 1000
One Pood = 3.6
One Eimer . =2.7
OneVedros = 2.7
One Miners' inch of water = 10
One column of water 1 foot high = . 434
One column of water 1 meter high = 1 . 43
A pressure of 1 lb. per square inch = 2.31
In the above, one ton = 2,240 lb.
Cubic inches
Cubic feet
Lb.
Liters
U. S. gallons
Cubic inches
Cubic feet
Lb.
Imperial gallons
Liters
Cubic inches
U. S. gallons
Imperial gallons
Imperial gallons
U. S. gallons
Cubic feet
Cubic feet
Imperial gallons
U. S. gallons
Liters (approx.)
Cubic meter (approx.)
Lb.
Imperial gallons
U. S. gallons
Ton
Cwt.
Lb.
Imperial gallons
U. S. gallons
Liters
Cubic meters
Imperial gallons
U. S. gallons
Cubic inches
Cubic feet
Imperial gallons
U. S. gallons
Cubic yards
Cubic feet
Cubic inches
Kilos
Ton (approx.)
Liters
Imperial gallons
Imperial gallons
Imperial gallons
Imperial gals, (approx.)
lib. pressure per sq. in.
Lb. pressure per sq. in.
Feet of water in height
Digitized
by Google
12
WEIGHTS AND MEASURES
Weight and Size
op Different Standard Gallons of Fresh
Water
Cubic "
Inches in
a Gallon
Weight of
a Gallon
in Pounds
Gallons
in a Cubic
Foot
Weight of a cubic
foot of fresh water,
English standard,
62 .321 lb. avoirdupois.
Imperial or English . . .
United Statea
277.274
231.
10.00
8.33111
6.232102
7.480519
Salt Water
The composition of salt water varies at different parts of the
world, but usually contains the following to every 100 parts:
Pure water 96.2 Sulphate of lime 08
Common salt 2 . 71 Sulphate of magnesium ... .12
Magnesium chloride 54 Calcium bicarbonate 01
Magnesium bromide 01 Organic matter 33
About 5 ounces of solid matter are present in one gallon of salt
water, and this density can be expressed as a fraction thus
solid matter __ 5 oz. __ 5 oz. __ 1_
water holding it in solution ~ lgal. "" 16 X 10 ~" 32
that is, one part in 32 of sea water is solid matter, if an Eng-
lish gallon of 10 lb. is used. If an American of 1 gal. = 8.33 lb.,
5 oz. 1
"26.7
then
16 X 8.33
Salt water boils at a higher temperature than fresh owing to its
greater density, as the boiling point of water is increased by any
substance that enters into combination with it. The property
water has of holding chemical substances, as salts of lime in solu-
tion, decreases as the temperature increases; from this follows that
boilers carrying a high steam pressure form more scale than those
working at lower temperatures and pressures.
Water is at its maximum density at 39.1° F. or 4° C. The boil-
ing point of fresh water at sea level is 212° F. and of salt water
213.2. Fresh water freezes at 32° F. or 0° C; salt water freezes
at a lower temperature. In freezing, water expands. Thus as
hot water cools down from the boiling point it contracts to 39.1°,
its maximum density, while below this temperature it expands again.
The British and United States standard temperature for specific
gravity is pure water at 62° F. Water has the greatest specific
heat of any known substance except hydrogen, and is taken as
the standard for all solids and liquids.
Digiti
zed by G00gk
Specific Gravities and Weights op Materials*
Material .
Alcohol, 100%.
Alum.
Aluminum, bronze
Aluminum, cast
Aluminum, sheet
Anthracite coal (broken) .
Antimony
Asbestos
Ash, white-red
Asphaltum
Babbitt metal
Barley
Barytes
Basalt
Bauxite
Beech
Bell metal
Benzine
Birch
Specific
Gravity1
.79
7.7
2.55-2.75
Bismuth
Bituminous coal (broken)
Boxwood
Brass, cast-rolled
Brick, common (1000 weigh about 3i tons) .
Bronze, 7.9 to 14% tin
Camphor
Cedar, white-red
Cement, Portland, loose
Chalk
Charcoal (piled)
Cherry
Chestnut
Clay, dry
Clay, moist
Coal — see anthracite and bituminous.
Coke
Concrete, cement — stone — sand.
Copper, cast, rolled
Copper ore, pyrites
Cork.
Corn.
Cotton, pressed
Cypress
Dolomite
Earth, dry loose
Earth, packed and moist.
Ebony
Elm..
1.4-1.7
6.7
2.1-2.8
.62-. 65
1.1-1.5
4.5
2.7-3.2
2.55
.73-. 75
9.74
.96
8.4-8.7
1.8-2.0
7.4-8.9
.32-. 38
i.*8-2.'6*
.70
.66
2.2-2.4
8.8-9.0
4.1-4.3
.25
1.25
.72
1.47-1.50
.48
2.9
Weight, lb.
per cu. ft.
49
107
478
160
168
47-58
417
153
40
81
456
38
281
184
159
' 44
503
46
33
608
49
63
534
120
509
62
22
90
137
10-14
42
41
63
110
23-32
144
556
262
15.6
48
93
30
181
76
96
79
45
1 The specific gravities of solids and liquids refer to water at 4° C. The weights
per cubic foot are derived from average specific gravities.
* From Pocket Companion. Carnegie Steel Co.
1Q
y Google
Specific Gravities and Weights of Materials — Continued
Material
Specific
Gravity
Weight, lb.
per cu. ft.
Emery
Felspar
Fir, Douglas (Oregon pine) .
Flagging
Flax
Flour, loose
Flour, pressed
Flint
Gasoline
Glass, common
Glass, plate or crown
Gold, cast, hammered
Gneiss, serpentine
Granite.-
Graphite
Greenheart
Gypsum
Hay and straw bales
Hemlock
Hickory
Hornblende
Ice
India rubber
Iron, cast, pig
Iron, wrought
Ivory
Kerosene
Lancewood
Lead
Lead, ore, galena
Leather
Lignum vita?
Lime, quick, loose
Limestone
Linseed oil
Locust '.
Manganese
Manganese ore . . .
Mahogany, Honduras
Mahogany, Spanish
Maple
Marble
Mercury
Mica
Muntz metal
Nickel
Nitric acid 91%
Oak, live „
2.5-2.6
.51
1.47-1.50
.4-. 5
.7-. 8
.66-. 69
2.4-2.6
2.45-2.72
19.25
2.4
2.5
1.9-2.3
2.3
.42-. 52
.74-. 84
3.
.88-. 92
7.2
7.6-7.9
.66
11.37
7.3
.86-1.02
1.10
2.5
.73
7.2-8.0
3.7
.65
13.6
8.9-9.2
1.5
.95
251
159
32
168
93
28
47
164
42
156
161
1205
159
175
131
62.5
159
20
29
49
187
56
58
450
485
114
42
42
710
465
59
83
53-60
165
58
46
475
259
35
53
49
170
• 849
183
511
565
94
59
14
Digitized by
Google
Specific Gravities and Weights of Materials — Continued
Material
Specific
Gravity
Weight, lb.
per cu. ft.
Oak, red, black
Oats, bulk
Oil — see gasoline, petroleum, etc.
Olive oil
Oregon pine
Paper
Petroleum, crude
Petroleum, refined
Phosphate rock
Phosphor bronze
Pine — long leaf yellow
Pine — short leaf yellow
Pine — white
Pitch ,
Platinum, cast, hammered
Plumbago
Poplar
Potatoes, piled
Quartz, flint
Rubber, caoutchouc
Rubber goods
Rye
Salt, granulated, piled
Saltpeter
Sand, dry, loose ".
Sand, wet
Sandstone
Shale, slate, piled
Silver, cast, hammered
Soapstone, talc
Spruce, white, black
Starch
Steel, cast
Steel, structural
Sulphur
Talc
Tallow
Tar, bituminous
Teak
Tin, cast, hammered
Tin ore
Walnut, black
Water, fresh
Water, salt
Wheat
White metal, Babbitt
Wool, pressed
Zinc, cast, rolled
Zinc ore, blende
.65
..51
.70
.87
.79
3.2
.70
.6
.41
1.07
21.1
.48
2.5
.92
1.-2.
2.2
10.4
2.6
.4
1.53
7.8
1.93
2.6
.82
7.2
6.4r-7.0
.61
1.
1.02
1.32
6.9
3.9
41
32
57
32
58
54
50
200
537
44
38
26
69
1330
140
30
42
165
59
94
48
48
67
90-105
120
147
92
656
169
27
96
493
. 490
125
169
59
75
52
459
418
38
62. £
64
48
456
82
440
253
-
15
Cubic Feet per Ton (2240 Le.) op Different Materials*
Material
Cu. ft.
per ton
Material
Cu. ft.
per ton
Alcohol in casks
80
70
108
120
90
52
70
50
53
17
65
90
59
47
68
47
93
125
80
54
74
45
60
85
50
50
52
85
80
110
55
80
124
155
22
65
70
50
56
43
80
184
240
40
38
70
60
80
Cider in casks
65
Almonds in bags
Cigars in cases
180
Almonds in hogsheads. . .
Aniseed in bags
Apples in boxes
Cinchona (Peruvian bark)
Cloth goods in cases
Cloves in cases
140
87
50
Arrowroot in bags ......
Arrowroot in boxes
Arrowroot in cases
Asbestos in cases
Coal (Admiralty)
Coal (American)
Coal (Newcastle)
Coal (Welsh)
48
.43
45
40
Asphalt
Cocoa in bags
80
Bacon in cases
Cocoanuts in bulk
Coffee in bags
140
Bananas
61
Barley in bags
Coir yarn in bales
Coke
190
Barley in bulk
80
Beans, haricot, in bags. .
Beans in bulk
Copper, cast
10
Copper ore
10-20
Beef, frozen, packed
Beef hung in quarters. . .
Beer, bottled, in cases. . .
Copper sulphate in casks
Copperas in casks
Copra in cases
50
52
85
Beer in hogsheads
Beeswax
Cork wood in bales
Cotton — a bale of U. S.
cotton is 54 ins. by 27 by
24 to 30 ins. high de-
pending on the com-
pression, assuming 30
ins. space occupied is
25.3 cu. ft. Average
stowage per ton
Cotton waste
270
Bone meal
Bones, crushed
Bones, loose
Books
Borate of lime
Borax in cases
Bottles, empty, in crates
Bran compressed in bales
Bran in bags
114
170
Cowrie shells in bags
Creosote in casks
Dates
75
Brandy, bottled, in cases
Brandy in casks
Bread in bulk
60
43
Earth, loose
25
Bread in cases
Bricks
Earthenware in crates. . .
Fish in boxes
47
95
Buckwheat in bags
Butter in kegs or cases. .
Camphor in cases
Candles in boxes
Canvas in bales
Carpets in rolls
Cassia in cases
Fish, frozen
60
Flax
105
Flour in bags
47
Flour in barrels
Freestone
Fuel oil
60
16
39-40
Furs in cases
130"
Cellulose
Ginger
80
Cement in barrels
Glass bottles
85
Chalk in barrels
Cheese
Glassware in crates
Granite blocks
180
16
Chicory in sacks
Chloride of lime in casks
Gravel, coarse
23
Grease
65
* From The Naval Constructor.
G. Simpson.
16
y Google
Cubic Peet per Ton (2240 Lb.) of Different Materials — Cont.
Material
Cu. ft.
per ton
Material
Cu. ft.
per ton
Guano. .
Gum
Gunny bags
Gunpowder
Hair, pressed
Ham in barrels
Hay, compressed
Hay, uncompressed .
Hemp in bales . .
Hemp seed in bags . . .
Herrings in barrels . . .
Herrings in boxes ....
Hides in bales
Hides in barrels
Hops in bales
Ice
India rubber, crude
Indigo in cases
Iron, corrugated sheets
Iron, pig
Ivory
Jute
Kaolin (China clay) in
bags...
Lard
Lead, pig
Lead pipes, random sizes
about..
Leather in bales
Leather in rolls
Lemons
Linseed in bags
Locust beams in bulk. . .
Logwood
Manure — phosphate. . . .
Maize in bags
Maize in bulk
Marble in slabs
Margarine in tubs
Marl
Matches
Melons
Milk, condensed, in cases
Millet in bags
Mineral water in cases .
Molasses in bulk
Molasses in puncheons.
Mutton
42
60
50
48
160
70
120
140
100
70
60
85
120
50
260
39
72
67
36
10
28
58
40
70
8
12
90
220
85
57
84
92
45
51
49
17
69
28
120
80
45
50
70
25
65
110
Nails, kegs ....
Nitrate of soda
Nuts, Brazil, in barrels.
Nuts, pistachio, in cases
Oatmeal in sacks
Oats in bags
Oats in bulk
Oil, lubricating, in bbls..
Oil in drums . . .
Oil in bottles in
Oil cake in bags..
, Olives in barrels..
Onions in boxes . .
Oranges in boxes .
Oysters in barrels
Paint in drums. ..
Paper in rolls ....
Peas in bags
Phosphate of lime
Pineapples, canned, and
in boxes
Pitch in barrels . . .
Potatoes in bags . .
Potatoes in barrels
Prunes in casks . . .
Raisins
Rape seed
Rice in bags
Rice meal
Rope
Rum in bottles and cases
Rum in hogsheads
Rye in bags
Salt in bulk . . .
Salt in barrels .
Saltpeter
Sand, fine
Sand, coarse. . .
Sandstone
Shellac
Silk in bales . . ,
Silk in cases . .
Slate
Soap in boxes.
Soda in ba_
Soda in cask
Sponge.
17
21
32
90
70
65
78
61
60
49
75
50
67
77
90
60
16
120
50
42
60
45
55
68
52
52
60
48
62
135
66
70
53
55
37
52
36
19
20
14
83
125
112
13
46
57
54
152
Cubic Feet per Ton (2240 Lb), of Different Materials — Cont.
Material
Cu. ft.
per ton
Material
Cu. ft.
per ton
Starch in cases ...
Stone, paving
Stone, limestone
Sugar in bags
Sugar in hogsheads . . .
Sugar in casks
Sulphur in bulk
Sulphur ip cases
Sulphur in kegs
Sumac in bags ..."
Syrup
Tallow in barrels and
tierces
Tallow in hogsheads. .
Tamarinds in cases . . .
Tamarinds in casks or
kegs
Tan extract
Tapioca
Tar in barrels
Tea, China, in chests . . .
Tea, Indian, in cases. . .
Ties, oak
100
50
80
15
13
40
54
60
27
40
60
70
34
58
70
45
54
48
57
54
100
Ties, steel
Tiles, roofing, in crates.
Tobacco, Brazilian, in
bales
Tobacco, Turkish, m
small bales
Turmeric
Turpentine in barrels .
Vermicelli
Water, fresh
Water, salt
Wheat in bags .
Wheat iit bulk
Whitening in casks . . .
Woods, sawn into planks
Ash
Beech
Elm
Fir
Greenheart
Mahogany
Wool in sheets
Wool in bales, pressed
38
85
40
150
80
60
110
36
35
52
48
39
39
51
60
65
34
34
260
100
Shipping Weights of American Lumber '
(Rough Lumber in lb. per lfiOO ft. board measure)
Ash, black 3,200
Ash, white 3,500
Basswood 2,500
Beech 4,000
Birch 4,000
Butternut 2,500
Cherry 3,800
Chestnut 2,800
Cottonwood 2,800
Douglas fir 3,300
Elm, rock 3,800
Elm, soft 3,000
Gum, red 3,300
Gum, sap
Hemlock
Hickory
Long leaf pine..
Mahogany ....
Maple, soft
Maple, hard. . .
Oak
Poplar, yellow.
Shortleaf pine .
Sycamore
Tupelo
Walnut
3,000
3,000
4,500
3,000
3,500
3,000
3,900
3,900
2,800
4,200
3,000
2,800
4,000
Weight of Green Logs per lfiOO ft. board measure
Yellow pine (Southern) 8,000 to 10,000 lb.
Norway pine (Michigan) 7,000 to 8,000 lb.
Hemlock (Pennsylvania), bark off w ,.. .6,000 to 7,000 lb.
18
bigitizedby^
WEIGHTS 19
Weights of Miscellaneous Units of Different Products
Lb.
Keg of nails 100
Firkin of butter 56
Chest of tea • 68
Barrel of flour, etc. — See Sizes of Barrels.
Bushel of oysters 80
Bushel of clams 100
Bushel of barley 48
Bushel of beans 60
Bushel of buckwheat 48
Bushel of charcoal 30
Bushel of castor beans 60
Bushel of clover seed 60
Bushel of corn (shelled) 56
Bushel of corn (on cob) 70
Bushel of malt 34
Bushel of onions - 57
Bushel of oats 32
Bushel of potatoes 60
Bushel of rye 56
Bushel of Timothy seed 45
Bushel of wheat 60
Quarter or 8 bushels of wheat 480
Gallon of molasses 12
Bale of United States cotton weighs 500
Bale of Peruvian cotton weighs 200
Bale of Brazilian cotton weighs 250
Bale of East Indian cotton weighs 400
Bale of Egyptian cotton weighs t 750
Bale of jute weighs 440
One bushel of wheat = 60 lb. = 1.244 cu. ft.
Eight bushels of wheat = one quarter = 9.952 cu. ft. = 480 lb.
One ton of wheat = 4% quarters = 46.43 cu. ft. = 2240 lb.
A case of kerosene oil generally contains two 5-gallon cans
or ten 1-gallon, in the former taking up 2 cu. ft. and in the
latter 2.1. Some hold fifteen 1-gallon cans and take up 3.2
cu. ft.
Gallon of honey 12
Gallon of crude oil about -. 8J^
7 bags of sugar (one ton) 2240
11 bags of potatoes (one ton) 2240
One bag of flour 140
Cord of dry hickory 4369
Cord of dry maple 2862
Linoleum M of an inch thick, including cement, weighs 1.5 lb.
per sq. ft.
Rubber tiling, & of an inch thick, weighs 2 lb. per sq. ft.
White tiling, A of an inch thick, weighs 6 lb. per sq. ft.
Digitized by VJiOOQLC
1
20 WEIGHTS AND MEASURES
Bundling Schedule for Buttweld Pipe1
This schedule applies to buttweld wrought iron pipe only.
Standard Weight Pipe
Size "£i2Er A°?SS'£°' AorBuMTnht
per Bundle BundfT Lb.
H • 42(Approx.)500 120
H 24 450 190
Vs 18 340 190
Y2 12 245 210
% 7 140 160
1 5 100 168
IK 3 60 138
llA.... 3 58 158
Extra Strong Pipe
Vs 42 ^ 500 157
H 24 450 241
Vs 18 330 244
}4 12 245 266
H 7 140 206
1 5 100 217
\\i 3 60 180
\y2 3 58 211
Double Extra Strong Pipe
Y2 7 126 215
M 5 95 230
1 3 60 220
lli 3 60 310
\y2 3 60 380
1 Adopted on June 1st, 1915, at the suggestion of the National Pipe and Supplies
Association.
Barrels
There is no standard size of barrel universally adopted either
by Great Britain or the United States. In Great Britain an old
wine barrel = 26 M imperial gallons, an ale barrel = 31 J^ imperial
gallons and a beer barrel = 36 J^ imperial gallons. A French
barrique of Bordeaux = 228 liters = 50 imperial gallons. Four
barriques = 1 tonneau.
Digitized by LiOOQ IC
BARRELS
21
A barrel for fruit, vegetables and other dry commodities as
fixed by a United States statute approved March 4, 1914, specifies
staves 28% ins. long, heads 17% ins. dia., distance between heads
26 ins., circumference 64 ins., all outside measurements, repre-
senting as nearly as possible 7050 cu. ins. or 4.08 cu. ft., equivalent
to 105 dry quarts. Besides the above the different states specify
the dimensions of barrels for various commodities. The usual
barrel for liquids contains 31% U. S. wine gallons of 231 cu. ins.
Below is a table of wood barrels.
Material Held
Diameter
Top and
Bottom
(ins.)
Diameter
at
Bilge
(ins.)
Height
(ins.)
Cubic Feet
Sugar. . .
Flour. . . ,
Oil
Fish. . . .
Meat . . .
Molasses
Salt....
Cement.
Lime . . .
Apple...
Potato..
Tar
19%
17%
21%
20
21%
22 %
18%,
16
16
17%
15
19%
21%
19%
25H
22%
25Ji
27%
21
18
18
19
21%
30
28%
33
30
33
35
30
28%
28%
28%
30
5.60
4.36
8.37
52 gals.
6.23
8.37
10.04
60 gals.
5.34
3.75
3.75
4.33
3.22
5.60
All dimensions are outside.
Rieley, Cleveland, O.
The above barrels are of wood, data from G. A.
An oil company (Piatt & Washburn Refg Co., New York) gave
the following figures on the sizes of their wood barrels and steel
drums:
Material
Wood
Wood half barrel
Drum (steel)
Half-drum
Diam.
Diam.
Wt. with
Top and
at
Length
Capacity
Oil
Bottom
Bilge
About
(ins.)
(ins.)
(ins.)
(gals.)
(lb.)
21
26
33Jrf
50
450
17
22
27
28
205
22
26
34
50
450
17
22
27
28
213
Tare
(lb.)
73
45
50
24
y Google
One horse power*
22 WEIGHTS AND MEASURES
Horse Powers
Horse Power (h. p.), the unit of power equivalent to raising a
weight of 33,000 lb. one foot in one minute.
2.64 lb. of water evaporated per hour from
and at 212° F.
746 watts
.746 kw.
33,000 ft. lb. per minute
550 ft. lb. per second
2,545 heat units per hour
42.4 heat units per minute
Indicated Horse Power (i. h. p.) is the power as measured by
an indicator and calculated by the following formula:
P = mean effective pressure in pounds per sq. in. on the piston
as obtained from the indicator card
L = length of stroke in ft.
A = area of piston in sq. ins.
N = number of single strokes per minute or two times the num-
ber of revolutions'
PLAN
Then indicated horse power (i. h. p.) =
33,000
Brake Horse Power (b. h. p.) is the actual horse power of an
engine as measured at the flywheel by a friction brake or dyna-
mometer. It is the indicated horse power minus the friction of
the engine.
Boiler Horse Power. — See Boilers.
Nominal Horse Power (n. h. p.). — Lloyd's formulae are as follows:
D = diameter of 1. p. cylinder in ins.
s = stroke in ins.
H = heating surface in sq. ft.
P = working pressure in pounds per sq. in.
N «= number of cylinders
(1) Where the boiler pressure and heating surface are known
*j h n = P + 340 /D2 y/s H\ where boiler pressure is be-
p' 1000 V 100 ^ 15/ low 160 lb.
_ P + 590 /D2 Vs /A where boiler pressure is
1500 V 100 "*" 15/ above 160 lb.
If boilers are fitted with forced or induced draft then H/12 is
substituted for H/15.
Digiti
zed by G00gk
HORSE POWER 23
Equivalent Values of Mechanical and Electrical Units
Unit
Equivalent Value in
Other Units
Unit
Equivalent Value in
Other Units
florae-
power =
(h. p.)
33,000 ft.-lb. per minute
550 ft.-lb. per second
746 watts
.746 kw.
2,545 heat units (B.t.u.)
per hour
42 . 4 heat units per minute
2.64 lb. water evap. per
hour, from and at 212° F.
1 Joule =
(J)
1 watt second
.00134 h. p. second
.000000278 kw. hour
.000954 heat units.
.7372 ft.-lb.
1 Foot-
pound =
(ft.-lb.)
1.356 joules
.0000005 h. p. hour
.000000377 kw. hour
1,000 watts
2,654,200 ft.-lb. per hour
44,232 ft.-lb. per minute
737 . 2 ft.-lb. per second
1.34 h. p.
3,412 heat units per hour
56 . 9 heat units per minute
3.53 lb. water evap. per
hour from and at 212d F.
.001285 heat units
. 1383 kilogram-meter
1 Kilo-
watt —
(kw.)
1 lb. water
evaporated
from and
at 212° F.
.379 h.p. hour
.283 kw. hour
751,300 ft.-lb.
967. heat units
1,019,000 joules
103,900 kilogram-meters
1 Kilogram
meter =
(kgm.)
1 British
Heat Unit
= (B.t.u.)
778 ft.-lb.
.000393 h. p. hour
.000293 kw. hour
1048 . watt seconds
.001036 lb. water evap.
from and at 212° F.
.00936 heat units
7.233 ft.-lb.
9.8117 joules
.00000365 h. p. hour
.00000272 kw. hour
(2) If boiler pressure and heating surface are not known
N. h. p. = for simple engines
loU
« 5LvT
120
for compound engines
10n for triple and quadruple engines
. (3) In vessels with Diesel engines
80
N X D2 Vs
N. h. p. = ^r for single actmg 4-cycle engines
40
N X D2 Vs~
20
for single acting 2-cycle engines
for double acting 2-cycle engines
Shaft Horse Power (s. h. p.) is the power delivered by the engine
or turbine to the shafting. See Turbines.
Digitized by vjivJUVLC
24
WEIGHTS AND MEASURES
Effective Horse Power (e. h. p.) See Powering Vessels.
Thrust Horse Power (t. h. p.) is the power delivered by the pro-
peller for the propulsion of the ship. Owing to the friction of the
working parts of the engine and shafting, the horse power trans-
mitted to the propeller is about \i of the indicated. Horse power
thrust in lb. X dist. ship travels in ft. in 1 min.
33000
used by the propeller =
Thrust in lb. =
33000 X h. p. used by the propeller
dist. ship travels in ft. in 1 min.
Comparison of Thermometer Scales
Cent.
Reau.
Fahr.
Cent.
Reau.
Fahr.
Cent.
Reau.
Fahr.
-40
-32.0
-40.0
21
16.8
69.8
62
49.6
143.6
-38
-30.4
-36.4
22
17.6
71.6
63
50.4
145.4
-36
-28.8
-32.8
23
18.4
73.4
64
51.2
147.2
-34
-27.2
-29.2
24
19.2
75.2
65
52.0
149.0
-32
-25.6
-25.6
25
20.0
77.0
66
52.8
150.8
-30
-24.0
-22.0
26
20.8
78.8
67
53.6
152.6
-28
-22.4
-18.4
27
21.6
80.6
68
54.4
154.4
-26
-20.8
-14.8
28
22.4
82.4
69
55.2
156.2
-24
-19.2
-11.2
29
23.2
84.2.
70
56.0
158.0
-22
-17.6
- 7.6
30
24.0
86.0
71
56.8
159.8
-20
-16.0
- 4.0
31
24.8
87.8
• 72
57.6
161.6
-18
-14.4
- 0.4
32
25.6
89.6
73
58.4
163.4
-16
-12.8
+ 3.2
33
26.4
91.4
74
59.2
165.2
-14
-11.2
6.8
34
27.2
93.2
75
60.0
167.0
-12
- 9.6
10.4
35
28.0
95.0
76
60.8
168.8
-10
- 8.0 ,
14.0
36
28.8
96.8
77
61.6
170.6
- 8
- 6.4
17.6
37
29.6
98.6
78
62.4
172.4
- 6
- 4.8
21.2
38
30.4
100.4
79
63.2
174.2
- 4
- 3.2
24.8
39
31.2
102.2
80
64.0
176.0
- 2
- 1.6
28.4
40
32.0
104.0
81
64.8
177.8
0
0.0
32.0
41
32.8
105.8
82
65.6
179.6
+ 1
+0.8
33.8
42
33.6
107.6
83
66.4
181.4
2
1.6
35.6
43
34.4
109.4
84
67.2
183.2
3
2.4
37.4
44
35.2
111.2
85
68.0
185.0
4
3.2
39.2
45
36.0
113.0
86
68.8
186.8
5
4.0
41.0
46
36.8
114.8
87
69.6
188.6
6
4.8
42.8
47
37.6
116.6
88
70.4
190.4
7
5.8
44.6
48
38.4
118.4
89
71.2
192.2
8
6.4
46.4
49
39.2
120.2
90
72.0
194.0
9
7.2
48.2
50
40.0
122.0
91
72.8
195.8
10
8.0
50.0
51
40.8
123.8
92
73.6
197.6
11
8.8
51.8
52
41.6
125.6
93
74.4
199.4
12
9.6
53.6
53
42.4
127.4
94
75.2
201.2
13
10.4
55.4
54
43.2
129.2
95
76.0
203.0
14
11.2
57.2
55
44.0
131.0
96
76.8
204.8
15
12.0
- 59.0
56
44.8
132.8
97
77.6
206.6
16
12.8
60.8
57
45.6
134.3
98
78.4
208.4
17
13.6
62.6
58
46.4
136.4
99
79.2
210.2
18
14.4
64.4
59
47.2
138.2
100
80.0
212.0
19
15.2
66.2
60
48.0
140.0
20
16.0
68.0
61
48.8
141.8
y Google
THERMOMETERS
25
Thermometers
i
Fahrenheit (F.) thermometer is used in the United States and
in Great Britain. The freezing point of water is marked 32 and
the boiling at sea level 212, the distance between these points is
divided into 180 parts or degrees. 32 parts are marked off from
the freezing point downwards, and the last one marked 0 or zero.
Centigrade (C.) is used extensively in Europe and in scientific
calculations. The freezing point of water is marked 0, and the
boiling point at sea level 100, and the distance between is divided
into 100 parts or degrees.
To convert Fahrenheit readings into Centigrade, subtract 32
and multiply by f. To convert Centigrade into Fahrenheit
multiply by I and add 32.
Reaumur (R.) is used in Russia. The freezing point of water is
taken as 0, and the boiling point 80. To convert Fahrenheit
readings into Reaumur subtract 32 and multiply by J.
To convert Reaumur into Fahrenheit multiply by f and add 32.
If the temperature be below freezing, "add 32" in the formula
becomes "subtract from 32" and "subtract 32" becomes "sub-
tract from 32." See table on page 24.
Circumferences and Are,:s op Circle Advancing by Eighths
Diameter
Circum.
.3927
.7864
1.178
1.570
1.963
2.356
2.741
. 3.141
3.534
3.927
4.319
4.712
5.105
5.497
5.890
6.283
6.675
7.068
7.461
7.854
8.246
8.639
9.032
9.424
Area
.0123
.0491
.110
.196
.306
.441
.601
.785
.994
1.227
1.485
1.767
2.074
2.405
2.761
3.141
3.546
3.976
4.430
4.908
5.411
5.939
6.491
7.068
Diameter
Circum.
9.817
10.210
10.603
10.996
11.388
11.781
12.174
12.566
12.959
13.352
13.744
14.137
14.530
14.923
15.315
15.708
16.101
16.493
16.886
17.279
17.671
18.064
18.457
18.850
Area
7.669
8.295
8.946
9.621
10.321
11.045
11.793
12.566
13.364
14.186
15.033
15.904
16.800
17.728
18.665
19.635
20.629
21.648
22.691
23.758
24.850
25.967
27.109
28.274
y Google
26 WEIGHTS AND MEASURES
MATHEMATICAL TABLES
Involution and Evolution
The quantity represented by the letter a multiplied by a quan-
tity represented by the letter b, is expressed a X b or ab.
Quantities in brackets thus (a + b) (a + b) signify they are to
be multiplied together.
To square a number multiply the number by itself. Thus the
square of 4 (often written 42) is 4 X 4 = 16.
To cube a number multiply the square by the number. Thus
cube of 4 (written 43) = 4X4X4 = 16 X4= 64.
To find the fourth power of a number, multiply the cube by
the number. Fourth power of 4 = 64 X 4 = 256.
The nth power of a number as an is obtained by multiplying
the logarithm of the number by n and then finding the number
corresponding to the logarithm. Thus 518= log. of 5 X 1.8, and
from the table of logarithms find the number corresponding to this
logarithm.
y/~~ isthe radical sign and either with or without the index figure
2 as \/ indicates that the square root of the quantity under it is
to be taken. Thus the VI is 2. \/ indicates the cube root is
to be taken as \/& is 2. \J~ that the fourth root as \/256 is 4.
The fourth root is the square root of the square root, and the sixth
root is the cube root of the square root.
Any root of a number as fya may be obtained by taking the
logarithm of the number a and dividing it by the index n and from
the table of logarithms finding the corresponding number.
To Extract the Square Root of a Number. — Point off the given
number into periods of two places each beginning with units. If
there are decimals, point these off likewise beginning at the decimal
point, and supplying as many ciphers as may be required.
Find the greatest number whose square is less than the first left-
hand period, and place it as the first figure in the quotient. Sub-
tract its square from the left-hand period, and to the remainder
annex the two figures of the second period for a dividend.
Double the first figure of the quotient for a partiaj^ivisor. Find
how many times the latter is contained in the dividend exclusive
of the right-hand figure, and set the figure representing that num-
ber of times as the second figure in the quotient and annex it to
the right of the partial divisor, forming the complete divisor. Mul-
y Google
SQUAKE AND CUBE ROOT 27
tiply this divisor by the second figure in the quotient and subtract
the product from the dividend. To the remainder bring down
the next period and proceed as before, in each case doubling the
figures in the root already found to obtain the trial divisor. Should
the product of the second figure in the root by the completed di-
visor be greater than the dividend, erase the second figure both from
the quotient and from the divisor, and substitute the next smaller
figure or one small enough to make the second figure by the divisor
less than or equal to the dividend.
Find the square root of 3.141592
3.141592 1 1.772 + square root
1
27
214
189
347
2515
2429
3542
8692
7084
To Extract the Cube Root. — Point off the number into periods
of three figures each, beginning at the right hand or units' place.
Point off decimals in periods of three figures from the decimal point.
Find the greatest cube that does not exceed the left-hand period,
write its root as the first figure in the required root. Subtract
the cube from the left-hand period, and to the remainder bring
down the next period for a dividend.
Square the first figure of the root, multiply by 300, and divide
the product into the dividend for a trial divisor, write the quotient
after the first figure of the root as a trial second figure.
Complete the divisor by adding to 300 times the square of the
first figure, 30 times the product of the first by the second figure
and the square of the second figure. Multiply this divisor by the
second figure, and subtract the product from the remainder. Should
the product be greater than the remainder the last figure of the root
and the complete divisor are too large; substitute for the last figure
the next smaller number and correct the trial divisor accordingly.
To the remainder bring down the next period, and proceed as
before to find the third figure of the root; that is, square the two
figures of the root already found, multiply by 300 for a trial di-
visor, etc. If the trial divisor is less than the dividend bring down
another period of three figures, and place 0 in the root and proceed
as before.
Digitized by VJiOOQlC
28 WEIGHTS AND MEASURES
The cube root of a number, will contain as many figures as there
are periods of three in the number.
Find the cube root of 1,881,365
1,881,365 | 123. -f- cube root
300 X l2^ = 30Q.
881
30X1X2,= 60
*
2* - i
364
728
300 X 122 - 43200
153365
30 X 12 X 3 - 1080
3s - 9
44289
132867
[Above examples from Mechanical Engineer's Pocket Book. Wm. Kent.]
Logarithms
The logarithm (log.) of a number is the exponent of the power
to which it is necessary to raise a fixed number or base to produce
the given number. Thus if the base is 10, the log. of 100 is 2, for
102 = 100. Logarithms having 10 as the base are called common
or Brigg's logarithms, while those with 2.718281 are hyperbolic or
Naperian. Common logarithms are given in the table on pages 29-30.
The hyperbolic log. of a number is equal to the common log. of the
number X 2.302585.
With the aid of logarithms, multiplication, division, involution
and evolution of large numbers may be shortened. Thus, to mul-
tiply two numbers, add their logarithms, and then find the number
whose logarithm is their sum. To divide one number into another,
subtract the logarithm of the smaller from the larger, and find the
number whose logarithm is the difference, which number will be
the quotient.
To raise a number to a given power, multiply the logarithm of
the number by the exponent of the power, and find the number
whose logarithm is the product.
To find any root of a number, divide the logarithm of the number
by the index of the root, and the quotient will be the logarithm of
the root; then by referring to the table of logarithms the number
can be found.
The logarithm of a number consists of two parts, viz., a whole
number called the characteristic, and a decimal or mantissa. The
characteristic is one less than the number of figures to the left
Digitized by VJiOOQ 1C
Squares, Cubes, Square Roots, Cube Roots, Logarithms,
Circumferences and Circular Areas of Nos. from 1 to 50
No.
- Dia.
Square
Cube
Square
Root
Cube
Root
Log.
No.
Circum.
Area
1
1
1
1.0000
1.0000
0.00000
3.142
0.7854
2
4
8
1.4142
1.2599
0.30103
6.283
3.1416
3
9
27
1.7321
1.4422
0.47712
9.425
7.0686
4
16
64
2.0000
1.5874
0.60206
12.566
12.5664
5
25
125
2.2361
1.7100
0.69897
15.708
19.6350
6
36
216
2.4495
1.8171
0.77815
18.850
28.2743
7
49
343
2.6458
1.9129
0.84510
21.991
38.4845
8
64
512
2.8284
2.0000
0.90308
25.133
50.2655
9
81
729
3.0000
2.0801
0.95424
28.274
63.6173
10
100
1000
3.1623
2.1544
1.00000
31.416
78.5398
11
121
1331
3.3166
2.2240
1.04139
34.558
95.0332
12
144
1728.
3.4641
2.2894
1.07918
37.699
113.097
13
169
2197
3.6056
2.3513
1.11394
40.841
132.732
14
196
2744
3.7417
2.4101
1.14613
43.982
153.938
15
225
3375
3.8730
2.4662
1.17609
47.124
176.715
16
256
4096
4.0000
2.5198
1.20412
50.265
201.062
17
289
4913
4.1231
2.5713
1.23045
53.407
226.980
18
324
5832
4.2426
2.6207
1.25527
56.549
254.469
19
361
6859
4.3589
2.6684
1.27875
59.690
283.529
20
400
8000
4.4721
2.7144
1.30103
62.832
314.159
21
441
9261
4.5826
2.7589
1.32222
65.973
346.361
22
484
10648
4.6904
2.8020
1.34242
96.115
380.133
23
529
12167
4.7958
2.8439
1.36173
72.257
415.476
24
576
13824
4.8990
2.8845
1.38021
75.398
452.389
25
625
15625
5.0000
2.9240
1.39794
78.540
490.874
26
676
17576
5.0990
2.9625
1.41497
81.681
530.929
27
729
19683
5.1962
3.0000
1.43136
84.823
572.555
28
784
21952
5.2915
3.0366
1.44716
87.965
615.752
29
841
24389
5.3852
3.0723
1.46240
91.106
660.520
30
900
27000
5.4772
3.1072
1.47712
94.248
706.858
31
961
29791
5.5678
3.1414
1.49136
97.389
754.768
32
1024
32768
5.6569
3.1748
1.50515
100.531
804.248
33
1089
35937
5.7446
3.2075
1.51851
103.673
855.299
34
1156
39304
5,8310
3.2396
1.53148
106.814
907.920
35
1225
42875
5.9161
3.2711
1.54407
109.956.
962.113
36
1296
46656
6.0000
3.3019
1.55630
113.097
1017.88
37
1369
50653
6.0828
3.3322
1.56820
116.239
1075.21
38
1444
54872
6.1644
3.3620
1.57978
119.381
1134.11
39
1521
59319
6.2450
3.3912
1.59106
122.522
1194.59
40
1600
64000
6.3246
3.4200
1.60206
125.66
1256.64
41
1681
68921
6.4031
3.4482
1.61278
128.81
1320.25
42
1764
74088
6.4807
3.4760
1.62325
131.95
1385.44
43
1849
79507
6.5574
3.5034
1.63347
135.09
1452.20
44
1936
85184
6.6332
3.5303
1.64345
138.23
1520.53
45
2025
91125
6.7082
3.5569
1.65321
141.37
1590.43
46
2116
97336
6.7823
3.5830
1.66276
144.51
1661.90
47
2209
103823
6.8557
3.6088
1.67210
147.65
1734.94
48
2304
110592
6.9282
3.6342
1.68124
150.80
1809.56
49
2401
117649
7.0000
3.6593
1.69020
153.94
1885.74
50
2500
125000
7.0711
3.6840
1.69897
157.08
1963.50
of the decimal point in the number whose logarithm is to be found.
Thus the -characteristic of numbers from 1 to 9.999 is 0, from 10 to
99.999 is 1, and so on. Should the number be a decimal with no
figures to the left of the decimal point, then the characteristic is
negative and is equal to the number of places the first figure is from
<j/\ Digitized by VjUUV
Squares, Cubes, Square Roots, Cube Roots, Logarithms,
Circumferences and Circular Areas of Nos. from 51 to 100
No.
= Dia.
Square
Cube
Square
Root
Cube
Root
Log.
No.
Circum.
Area
51
2601
132651
7.1414
3.7084
1.70757
160.22
2042.82
52
2704
140608
7.2111
3.7325
1.71600
163.36
2123.72
53
2809
148877
7.2801
3.7563
1.72428
166.50
2206.18
54
2916
157464
7.3485
3.7798
1.73239
169.65
2290.22
55
3025
166375
7.4162
3.8030
1.74036
172.79
2375.83
56
3136
175616
7.4833
3.8259
1.74819
175.93
2463.01
57
3249
185193
7.5498
3.8485
1.75587
179.07
2551.76
58
3364
195112
7.6158
3.8709
1.76343
182.21
2642.08
59
3481
205379
7.6811
3.8930
1.77085
185.35
2733.97
60
3600
216000
7.7460
3.9149
1.77815
188.50
2827.43
61
3721
226981
7.8102
3.9365
1.78533
191.64
2922.47
62
3844
238328
7.8740
3.9579
1.79239
194.78
3019.07
63
3969
250047
7.9373
3.9791
1 . 79934
197.92
2117.25
64
4096
262144
8.0000
4.0000
1.80618
201.06
3216.99
65
4225
274625
8.0623
4.0207
1.81291
204.20
3318.31
66
4356
287496
8.1240
4.0412
1.81954
207.35
3421.19
67
4489
300763
8.1854
4.0615
1.82607
210.49
3525.65
68
4624
314432
8.2462
4.0817
1.83251
213.63
3631.68
69
4761
328509
8.3066
4.1016
1.83885
216.77
3739.28
70
4900
343000
8.3666
4.1213
1.84510
219.91
3848.45
71
5041
357911
8.4261
4.1408
1.85126
223.05
3959.19
72
5184
373248
8.4853
4.1602
1.85733
226.19
4071.50
73
5329
389017
8.5440
4.1793
1.86332
229.34
4185.39
74
5476
405224
8.6023
4.1983
1.86923
232.48
4300.84
75
5625
421875
8.6603
4.2172
1.87506
235.62
4417.86
76
5776
438976
8.7178
4.2358
1.88081
238.76
4536.46
77
5929
456533
8.7750
4.2543
1.88649
241.90
4656.63
78
6084
474552
8.8318
4.2727
1.89209
245.04
4778.36
79
6241
493039
8.8882
4.2908
1.89763
248.19
4901.67
80
6400
512000
8.9443
4.3089
1.90309
251.33
5026.55
81
6561
531441
9.0000
4.3267
1.90849
254.47
5153.00
82
6724
551368
9.0554
4.3445
1.91381
257.61
5281.02
83
6889
571787
9.1104
4.3621
1.91908
260.75
5410.61
84
7056
592704
9 . 1652
4.3795
1.92428
263.89
5541.77
85
7225
7*396
614125
9.2195
4.3968
1.92942
267.04
5674.50
86
636056
9.2736
4.4140
1.93450
270.18
5808.80
87
7569
658503
9.3274
4.4310
1.93952
273.32
5944.68
88
7744
681472
9.3808
4.4480
1.94448
276.46
6082.12
89
7921
704969
9.4340
4.4647
1.94939
279.60
6221.14
90
8100
729000
9.4868
4.4814
1.95424
282.74
6361.73
91
8281
753571
9.5394
4.4979
1.95904
285.88
6503.88
92
8464
778688
9.5917
4.5144
1.96379
289.03
6647.61
93
8649
804357
9.6437
4.5307
1.96848
292.17
6792.91
94
8836
830584
9.6954
4.5468
1:97313
295.31
6939.78
95
9025
857375
9.7468
4.5629
1.97772
298.45
7088.22
96
9216
884736
9.7980
4.5789
1.98227
301.59
7238.23
97
9409
912673
9.8489
4.5947
1.98677
304.73
7389.81
98
9604
941192
9.8995
4.6104
1.99123
307.88
7542.96
99
9801
970299
9.9499
4.6261
1.99564
311.02
7697.69
100
10000
1000000
10.0000
4.6418
2.00000
314.16
7852.98
the decimal point. Thus the characteristic of numbers from .1
to .999 is - 1, from .01 to .099 is - 2, .0000072 is - 6, etc. The
mantissa or decimal part is only given in the table/ the decimal
point being omitted. The minus sign is frequently placed above
the characteristic thus: log. .31830 = 1.50285 or 9.50285 - 10.
30
JvJ\JvI^
GEOMETRICAL PROPOSITIONS 31
If a number is multiplied or divided by any integral power of
10, producing another number with the same sequence of figures,
the mantissae of their logarithms will be equal. To find the logarithm
of a number take from the table the mantissa corresponding to its
sequence of figures, and the characteristic may be prefixed by the
rule given above.
Thus if log. of 3.053 = .484727
log. 30.53 = 1.484727 log. .3053 - 9.484727 -10
log. 305.3 =2.484727 log. .03053 =8.484727-10
log. 3053. = 3.484727 log. .003053 = 7.484727 -10
The above property is only enjoyed by the common or Brigg's
logarithms and constitutes their superiority over other systems of
logarithms.
-Geometrical Propositions
The sum of the angles of a triangle is equal to 180°.
If a triangle is equilateral it is equiangular.
In a right-angled triangle the square on the hypothenuse is equal
to the sum of the squares of the other two sides.
A straight line from the vertex of an isosceles triangle perpendicu-
lar to the base bisects the base and the vertical angle.
A circle can be drawn through any three points not in the same
straight line.
If a triangle is inscribed M in a semicircle, it is right-angled.
In a quadrilateral the sum of the interior angles is equal to four
right angles or 360°.
In a parallelogram the opposite sides are equal, as also the oppo-
site angles are equal.
A parallelogram is bisected by its diagonals, which in turn are
bisected by each other. .
If the sides of a polygon are produced, then the sum of the exterior
angles is equal to four right angles.
The areas of two circles are to each other as the squares of their
radii.
If a radius is perpendicular to a chord, it bisects the chord and
the arc subtended by the chord.
From a point without a circle only two tangents can be drawn
to the circle. The tangents so drawn are equal.
A straight line tangent to a. circle meets it at one point, and it
is perpendicular to the radius drawn to that point.
Digitized
by Google
32 WEIGHTS AND MEASURES
If an angle is formed by a tangent and a chord, it is measured
by one-half of the arc intercepted by the chord.
If an angle at the circumference of a circle between two chords
is subtended by the same arc as an angle at the center between
two radii, the angle at the circumference is equal to half the angle
at the center.
Properties op Circles and Ellipses
Circle. — The ratio of the circumference of a circle to its diameter
is 3.141592 and is represented by the symbol ir (called Pi)
Circumference of a circle = diameter X 3.14159
Diameter of circle X .88623 1 ., - ,
Circumference of circle X .28209 } = Slde of equal 8quaXe
Circumference of circle X 1.1284 = perimeter of equal square
Side of square of equal periphery as circle = diameter X .7854
Diameter of circle circumscribed about square = side X 1.4142
Side of square inscribed in circle = diameter X .70711
To find the length of an arc of a circle, multiply the diameter
of the circle by the number of degrees in the arc and this product
by .0087266. Or let C represent the length of the chord of the
arc and c the length of the chord of half the arc, then the length
t *u 8c - C
of the arc = — 5
Chord of the arc = 2 X radius X sin angle ^g"*8
Rise (the perpendicular distance from the center of the chord
to the arc) = radius — XA V 4 radius2 — length of chord2
o w j- w • 9 an8le in degrees
= 2 X radius X sin2 — -. — -
4
For areas of segments and sectors see Areas.
x = 3.1415926 log. = 0.497149
ir __
T ~~
1 =
x
ir _
180 ~
180
.7853982
log. = 1.895090
.0318309
log. = T.5028501
.0174533
log. = 2.2418774
57.2957795
log. - 1.7581226
Digitized by VjiOOQ 1C
AREAS 33
Ellipse. Let D «= major axis
d *s minor axis
Approximate circumference = 3.1416 y ^ —
Area = D XdX .78539
_ ££* X 3.14159
Areas of Plane Figures and Surfaces of Solids
Plane Figures.
Triangle = base X Vi altitude
= y/ s (s — a) (a — b) (a — c) where 8 = J^ sum
of the three sides a, b and c
Parallelogram = base X altitude
Trapezoid = altitude X 14 the sum of the parallel sides
Trapezium = divide into two triangles and find area of the
triangles
Circle = diameter2 X .7854 = x X radius2
Sector of circle = length of arc X \i the radius
_ it X radius2 X angle in degrees ^.^ ^
360 = -0087266 x
radius2 X angle in degrees
Segment of circle. — Where the line forming the segment cuts the
circle, draw lines to the center forming a sector and a center angle A.
r™ - , radius2 /3. 1416 X A in degrees . A
Then area of segment = — ^ — 1 ioq ~ — — sm A 1
Circle of same area as square: diameter = side X 1.12838
Square of same area as circle: side — diameter X .88623
Ellipse = long diameter X short diameter X .7854
Parabola = base X % perpendicular height.
Regular polygon = sum of its sides X perpendicular from its
center to one of its sides divided by 2. Or multiply J^ the
perimeter by the perpendicular from the center to a side.
Irregular polygon: draw diagonals dividing it into triangles, and
find the sum of the areas of the triangles.
Trapezoidal Rule. — To find the area of a curvilinear figure, as
ABC D (see Fig. 1), divide the base into any number of con-
venient equal parts, and erect perpendiculars meeting the curve.
To the half sum of the first and last perpendiculars add the sum of
all the intermediate ones; then the sum multiplied by the common
interval will give the area.
Digitized by VjOOQIC
34
WEIGHTS AND MEASURES
m j j i r
t ^ T V *» » *
Figure 1
Let 7i = the common interval
2/i, ffc) etc., lengths of the perpendiculars to the line A D
Then the area A B C D = h {^^ + 2/2 + 2/* + 2/4 + 2/5 + 2/e)
Simpson's First Rule. — This rule assumes that the curved line
B C forming one side of the curvilinear area A B C D (see Fig. 2)
is a portion of a curve known as a parabola of the second order
whose equation is y = ax2 + bx + c.
Figure 2
Divide the base into any convenient even number of parts, and
erect perpendiculars to meet the curve. To the sum of the end
perpendiculars or ordinates add four times the even numbered
ordinates and twice the odd numbered ordinates. Multiply the
sum by one-third the common interval and the product will be
the area.
Thus the area A B C D in Fig. 2=4" (2/1 + %2 + yz)
o
Or the area of A B C D in Fig. 1 = y (yx+ 42/2+ 2y*+ 4y4+ 2yh
+ 42/6+ 2/7)
Digiti
zed by G00gk
SIMPSON'S SECOND RULE
35
It is found that areas given by the above approximate rule for
curvilinear figures are very accurate, and the rule is extensively
used in ship calculations.
Example. The ordinates to a curve are 1.5, 3.1, 5.2, 6.0, 6.5, 7.0, 8.1, 8.5
.ad 9 .0 ft., the common interval is 3 ft. Find the area.
Number of
Ordinate
Length of
Ordinate
Simpson's
Multipliers
Functions of
Ordinates
1
1.5
3.1
5.2
6.0
6.5
7.0
8.1
8.5
9.0
1
4
2
4
2
4
2
4
1
1 5
2
12 4
3
10 4
4
24 0
5
13 0
6
28 0
7
16 2
8
34 0
9
9.0
Common interval » 3 ft.
Then the area = H X 3 X 148.5 = 148.5 aq. ft.
148.5
. The multipliers may be ^ of those given in the example, viz.,
1 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, Yz and the sum of the functions multiplied
by % the common interval as above. The H multipliers are in
some cases easier to work with, as the sum of the functions is a
smaller number.
Simpson's Second Rule assumes that the curve B C (see Fig. 3)
is part of a parabola of the third order, where y — ax + bx + ex.
LLU,
Figure 3
Sh
The area of the curve A B C Dy Fig. 3, is -g- {yi + Zy2 + Sy» + 2/0
or the curve in Fig. 1 is -g- (yx+ 3y2+ 3y8+ 2t/4+ 32/5+ 3i/6+ t/7)
Here the number of ordinates must be a multiple of 3 plus 1.
Digitized by VjiOOQIC
36 WEIGHTS AND MEASURES
Simpson's first rule is used more than the second as it is simpler
and is quite as accurate.
Surface of Solids. — Lateral surface of a right or oblique prism
or cylinder = perimeter of the base X lateral length. To get the
total surface add the areas of the bases to the lateral surface.
Pyramid or cone, right and regular, lateral surface = perimeter
of base X XA slant height. To get total surface add area of base.
Frustum of pyramid or cone, right and regular parallel ends,
lateral surface = (sum of perimeters of base and top) X M slant
height. To get total surface add areas of the bases to the lateral
surface.
Surface of a sphere = 4 ir radius2 = w diameter8.
Surface of spherical sector = J^ x r (4 6 + c). See Fig. 4.
Surface of a spherical segment = 2 *• r 6 =■ % * (4 62 + c2). See
Fig. 5.
Surface of a spherical zone = 2 w r b. See Fig. 6.
Surface of a circular ring = 4 ir2 R r. See Fig. 7.
Surface of a regular polyhedron (a solid whose sides are equal
regular polygons) = area of one of the faces X the number of faces.
Volumes of Solids
Prism, right or oblique regular or irregular. — Volume = area of
section perpendicular to the sides X the lateral length of a side.
Cylinder, right or oblique, circular or elliptic, etc. — Volume =
area of section perpendicular to the sides X the lateral length of
a side.
Frustum of any prism or cylinder. — Volume = area of base X
perpendicular distance from base to center of gravity of opposite
face.
Pyramid or cone, right or oblique, regular or irregular. — Volume
= area of base X H the perpendicular height.
Frustum of any pyramid or cone, parallel ends. — Volume =
(sum of the areas of base and top plus the square root of their
products) X H the perpendicular height.
Wedge, parallelogram face. — Volume = sum of three edges X
perpendicular height X perpendicular width.
Sphere. — Volume = }x (radius)8 or (diameter)8 X .5236.
Digitized by VjiOOQIC
VOLUMES OF SOLIDS
37
Volume - 3i x r* b .
Figure 4
Spherical Sector
Volume - \i ir 6* (3 r - 6)
Figure 5
Spherical Segment
—I
5
Volume = ^ x 6 (3a*+ 3c»+ 46»)
Figured
Spherical Zone
^-/? — ihA*
b
d
Volume - 2 ** 22 r«
Figure 7
Circular King
3
Digiti
zed by G00gk
38
WEIGHTS AND MEASURES
Volume » \4 rrab
V-^r^£*%j
Figure 8
Ellipsoid
Volume = % x r8 h
Figure 0
Paraboloid
Regular polyhedron. — Volume = area of its surface X H the per-
pendicular from the center to one of the faces.
The volume of any irregular prismatic solid may be obtained by
dividing it into prisms or other bodies whose contents can be calcu-
lated by the above formulae. The sum of the contents of these
bodies will give the total volume of the solids.
To find the volume of a solid bounded by a curved surface, as the
underwater portion of a ship's hull, divide the solid by a series of
planes or sections spaced an equal distance apart.
The area of each section can be calculated by either the tra-
pezoidal or Simpson's rule, or by means of an instrument called a
planimeter. The areas of the sections can be laid off on ordinates
which are spaced the same distance apart as the sections which
the body was divided into. A curve is drawn through the points
laid off on the ordinates, and the area of the curvilinear figure is
the volume of the solid.
Example. The areas of cross sections of a ship below the load water line are 1.2,
17.6, 41.6, 90.7, 134.3, 115.4. 61.7, 30.4 and 6.6 sq. ft. The sections are 0.5 ft.
apart. Find the volume in cubic feet, and the displacement in tons of salt water.
Digitized by >
JvJ^Vl^
TRIGONOMETRY
39
Number of Section
Area
Simpson's
Multipliers
Functions of Areas
1
1.2
17.6
41.6
90.7
134.3
115.4
61.7
30.4
6.6
1
4
2
4
2
4
2
4
1
1.2
2
70.4
3
83.2
4
362.8
5
268.6
6
661.6
7
123 4
8
121.6
9
6.6
1,699.4
Volume - X X 9.5 ft. X 1,699.4 = 5,381.4 cu. ft.
5,381.4
Displacement = = 153.7 tons
35
To find the volume of a cross coal bunker or a side bunker having
the same cross section throughout, divide the height into inter-
vals and calculate the area of the section by Simpson's first rule.
Multiply the area thus found by the length of the bunker, giving
the capacity in cubic feet. To convert this into tons divide by
42, as 42 cu. ft. is usually taken as one ton of 2240 lb.
Trigonometry
The complement of an angle or arc is what remains after sub-
tracting the angle or arc from 90°. If an arc is represented by A,
its complement is 90° —A. Hence the complement of an arc that
exceeds 90° is negative.
The supplement of an angle or arc is what remains after sub-
tracting the angle or arc from 180°. If A is an arc, its supplement
is 180° —A. The supplement of an arc that exceeds 180° is negative.
jvJ^v^
40 WEIGHTS AND MEASURES
As the sum of the three angles of a triangle is equal to 180°, any
angle is the supplement of the other two.
Trigonometric Functions. — In the right triangle (Fig. 10) if A
is one of the acute angles, a the opposite side, b the adjacent side
and c the hypotenuse,
sineof angle A . yorfte side _ a
hypotenuse c
cosineofangle A - ^jacentside . ±
hypotenuse c
tangent of angle A - ^B2g*gJ^» _ «
-^y. adjacent side b
cotangent of angle A - ^jacent^e . ±
opposite side a
seeantof angle A = hypotenuse _ e
adjacent side o
cosecant of angle A - ^^"j* - -£■
opposite side <*
versed sine of angle A — 1 — cosine A
exsecant of angle A — secant A — 1
For angle B
a
b
tan B - -
a
cosec £ — 4"
o
tan A — cotan B — -r- cosec A = sec 2* =» — ■'
6 a
If a circle is divided into four quadrants, the upper right-hand
quadrant is called the first, the upper left the second, the lower
left the third, and the lower right the fourth. The signs of the
functions in the four quadrants are as follows:
sin B — —
c
cotan B —
coeB -i
c
sec £ -
tanfl - -^
a
cosec £ —
sin A = cos
B
-
C
cotan A =»
cos A — sin
B
-
b^
c
sec A —
OBLIQUE TRIANGLES 41
First Second Third Fourth
Sine and cosecant + + — — •
Cosine and secant -f — — +
Tangent and cotangent + — + —
The symbol sin'1^ means the angle whose sine is x, and is read
inverse sine of x and anti sine of x (also arc sine x). Similarly
cos_1x, tan~lz, etc. While the direct functions sine, cos, etc., are
single valued, the indirect are many, thus sin 30° = .5, but sin_1.5 =
30° or 150°.
If an acute angle and one side or if two sides of a right triangle
are given the other elements can be determined. Let A and B be
acute angles (see Fig. 10), a and b the sides opposite them. The
acute angles are complementary, that is A + B = 90°. ~Five cases
may be distinguished.
Given c and A then a — c sin A, b » e cos B
a " A b = a cot A, c = a cosec A
b " A a = b tan A, c — b sec A
a " c A - sin"1 y, 6 =V(c+a) (c-a)
a " b A - tan_1y, c - Vtf+&
Solution of Oblique Triangles. — If any three of the six elements
(three angles and three sides) of a triangle are known, the remain-
ing three can be found, provided one of the given three is a side.
There are four cases as follows:
Case 1. Given one side and two angles.
The third angle equals 180° minus the sum of the two given.
-r* xu • • j u *v * a sin B , a sin C
If the given side be a then 6 — —. — j- and c « — - : — r-
sm A Bin A
Case 2. Given two sides (a and b) and the included angle C.
Then A = H (A + B) + Yz (A - B)
B - H(A+H) -H(A -£)
a sin C
c -= — : — j-
sm A
Case S. Given two sides a and 6, and the angle A opposite one
of them.
sin B « — sin A giving two values of B, one acute and one
a
obtuse unless sin B > 1 in which case the data are impossible. Call-
ing these two values 2?i and B2, then
Digiti
zed by G00gk
42 WEIGHTS AND MEASURES
corresponding to Bh d = 180 — (A + #)i and ci = — — j^
sin A
B„ ft = 180 - (A + *),
a sin ft .
sin A
That is, there are two solutions unless ft<0 when only the first
holds. A triangle should be constructed as then the two solutions
will become more evident.
Case 4. Given the three sides. Let * = }4 (<* + b + c)
Then cos }4 A - i/* (* ~ a)
r 6c
%£ -|/t
6c
cosHC»4/L(i^l>
f ab
There are two kinds of trigonometrical tables for the computa-
tion of the sides and angles of a triangle, viz., natural sines, tan-
gents, etc., and logarithmic sines, tangents, etc. Natural sines,
tangents, etc., are calculated for a circle whose radius is unity,
and logarithmic sines, tangents, etc., for a circle whose radius is
10,000,000,000. With natural sines long operations in multipli-
cation and division are necessary, while with logarithmic sines
these operations in conjunction with a table of logarithms are
reduced to addition and subtraction.
Trigonometric Formulae. — tan A ■■ -p sec A a —
B cos A cos A
tan A = — 7 r cotan A = — — -r cosec A
— cotan A— sin A sin A
sin1 A + cos* A = 1
i + tan* A « sec* A 1 + cotan* A = cosec1 A
sin (A + B) = sin A cos B + cos A sin B
cos (A + B) = cos A cos B — sin A sin B
sin (A — B) =■ sin A cos B — cos A sin B
cos (A — B) = cos A cos B + sin A sin B
2 tan A
sin 2 A = 2 sin A cos A tan 2 A
cos 2 A a cos* A — sin1 A cotan 2 A
1 -tan2 A
cot* A - 1
2 cotan A
aia^-*,/1-^ tan HA^i/)-^
V 2 V 1 + cos A
cos A
cos J^ A - ± |/L±|°lii Cotan H A = ± j/^
Digiti
cos A
zed by G00gk
SINES, COSECANTS, TANGENTS, ETC. 43
Natural Sines, Cosecants, Tangents, etc.
•
1
Sine
Cosecant
Tangent
Cotangent
Secant
Cosine
•
o
0
0
.000000
Infinite.
.000000
Infinite.
1.00000
1.000000
0
M
10
.002909
343.77516
.002909
343.77371
1.00000
999996
50
20
.005818
17188831
.006818
171.88540
1.00002
999983
40
30
.008727
114.59301
.008727
114.58865
1.00004
'. 999962
30
40
.011635
85.945609
.011636
85.939791
1.00007
.vWtMJ
20
50
.014544
68.757360
.014545
68.750087
1JD0011
.999894
10
1
0
.017452
57.298688
.017455
57.289962
1.00015
.999848
0
89
10
.020361
49.114062
.020365
49.103881
1.00021
.999793
50
20
.023269
42.975713
.023275
42.964077
1.00027
.999729
40
30
.026177
38.201550
.026186
38.188459
1.00034
.999657
30
40
.029085
34.382316
.029097
34.367771
1.00042
.999577
20
50
.031992
31.257577
.032009
31.241577
1.00051
.999488
10
2
0
.034899
28.653708
.034921
28.636253
1.00061
.999391
0
88
10
.037806
26.450510
.037834
26.431600
1.00072
.999285
50
20
.040713
24.562123
.040747
24.541758
1.00083
.999171
40
30
.043619
22.925586
.043661
22.903766
1.00095
.999048
30
40
.046525
21.493676
.046576
21.470401
1.00108
.998917
20
50
.049431
20.230284
.049491
20.205553
1.00122
.998778
1C
3
0
.052336
19.107323
.052408
19.081137
1.00137
.998630
0
87
10
.055241
18.102619
.055325
18.074977
1.00153
.998473
50
20
.058145
17.198434
.058243
17.169337
1.00169
.998308
40
30
.061049
16.380408
.061163
16.349855
1.00187
.998135
30
40
.063952
15.636793
.064083
15.604784
1.00205
.997357
20
50
.066854
14.957882
.067004
14.924417
1.00224
.997763
10
4
0
.069756
14.335587
.069927
14.300666
1.00244
.997564
0
86
10
.072658
13.763115
.072851
13.Z26738
1.00265
.997357
50
20
.075559
13.234717
.075776
13.196888
1.00287
1.00309
.997141
40
30
.078459
12.745495
.078702
12.706205
.996917
30
40
.081359
12.291252
.081629
12.250505
1.00333
.996685
20
50
.084258
11.868370
.084558
11.826167
1.00357
.996444
10
5
0
.087156
11.473713
.087489
11.430052
1.00382
.996195
0
85
10
.090053
11.104549
.090421
11.059431
1.00408
.995937
50
20
.092950
10.758488
.093354
10.711913
1.00435
.995671
40
30
.095846
10.433431
.096289
10.385397
1.00463
.995396
30
40
.098741
10.127522
.099226
10.078031
1.00491
.995113
20
50
.101635
9.8391227
.102164
9.7881732
1.00521
.994822
10
•
0
.104528
9.5667722
.105104
9.5143645
1.00551
.994522
0
84
10
.107421
9.3091699
.108046
9.2553035
1.00582
.994214
50
20
.110313
9.0651512
.110990
9.0098261
1.00614
.993897
40
83
o
i
Cosine
Secant
Cotangent
Tangent
Cosecant
Sine
'
o
For functions from 83° 40' to 90° read from bottom of table upwwd.
Digitized by VJiOOQLC
U WEIGHTS AND MEASURES
Natural Sines, Cosecants, Tangents, etc. — Continued
o
/
Sine
Cosecant
Tangent
Cotangent
Secant
Cosine
'
e
6
30
.113203
8.8336715
.113936
8.7768874
1.00647
.993572
30
40
.110093
8.6137901
.116883
8.5555468
1.00681
.993238
20
60
.118982
8.4045586
.119833
8.3449558
1.00715
.992896
10
7
0
.121869
8.2055090
.122785
8.1443464
1.00751
.992546
0
83
10
.124756
8.0156450
.125738
7.9530224
1.00787
.992187
50
20
.127642
7.8344335
.128694
7.7703506
1.00825
.991820
40
30
.130526
7.6612976
.131653
7.5957541
1.00863
.991445
30
40
.133410
7.4957100
.134613
7.4287064
1.00902
.991061
20
50
.136292
7.3371909
.137576
7.2687255
1.00942
.990669
10
8
0
.139173
7.1852965
.140541
7.1153697
1.00983
.990268
0
82
10
.142053
7.0396220
.143508
6.9682335
1.01024
.989859
50
20
.144932
6.8997942
.146478
6.8269437
1.01067
.989442
40
30
.147809
6.7654691
.149451
6.6911562
1.01111
.989016
30
40
.150686
6.6363293
.152426
6.5605538
1.01155
.988582
20
60
.153561
6.5120812
.155404
6.4348428
1.01200
.988139
10
9
0
.156434
6.3924532
.158384
63137515
1.01247
.987688
0
81
10
.159307
6.2771933
.161368
6.1970279
1.01294
.987229
50
20
.162178
6.1660674
.164354
6.0844381
1.01342
.986762
40
30
.165048
6.0588980
.167343
5.9757644
1.01391
.986286
30
40
.167916
5.9553625
.170334
5.8708042
1.01440
.965801
20
50
.170783
5.8553921
.173329
5.7693688
1.01491
.985309
10
* 10 %
0
.173648
5.7587705
.176327
5.6712813
1.01543
.984808
0
80
10
.176512
5.6653331
.179328
5.5763786
1.01595
.984298
50
20
.179375
5.5749258
.182332
5.4845052
1.01649
.983781
40
30
.182236
5.4874043
.185339
5.3955172
1.01703
.983255
30
40
.185095
5.4026333
.188359
5.3092793
1.01758
.982721
20
50
.187953
5.3204860
.191363
5.2256647
1.01815
.982178
10
11
0
.190809
5.2408431
.194380
5.1445540
1.01872
.981627
0
70
10
.193664
5.1635924
.197401
5.0658352
1.01930
.981068
50
20
.196517
5.0886284
.200425
4.9894027
1.01989
.980500
40
30
.199368
5.0158317
.203452
4.9151570
1.02049
.979925
30
40
.202218
4.9451687
.206483
4.8430045
1.02110
.979341
20
50
.205065
4.8764907
.209518
4.7728568
1.02171
.978748
10
1»
0
.207912
4.8097343
.212557
4.7046301
1.02234
.978148
0
78
10
.210756
4.7448206
.215599
4.6382457
1.02298
.977539
50
20
.213599
4.6816748
.218645
4.5736287
1.02362
.976921
40
30
.216440
4.6202263
.221695
4.5107085
1.02428
.976296
30
40
.219279
4.5604080
.224748
4.4494181
1.02494
.975662
20
50
.222116
4.5021565
.227806
4.3890940
1.02562
.975020
10
77
0
/
Cosine
Secant
Cotangent
Tangent
Cosecant
Sine
'
o
For functions from 77° 10' to 83° 30' read from bottom of table upward.
Digitized by LiOOQ LC
SINES, COSECANTS, TANGENTS, ETC. 45
Natural Sines, Cosecants, Tangents, etc. — Continued
o
i
Sine
Cosecant
Tangent
Cotangent
Secant
Cosine
'
o
13
0
.224051
4.4454115
.230868
4.3314759
1.02630
.974370
0
77
10
.227784
4.3901158
.233934
4.2747066
1.02700
.973712
50
20
.230616
4.3362150
.237004
4.2193318
1.02770
.973045
40
30
.233445
4.2836576
.240079
4.1652998
1.02842
.972370
30
40
.236273
4.2323943
.243158
4.1125614
1.02914
.971687
20
50
.236098
4.1823785
.246241
4.0610700
1.02987
.970995
10
14
0
.241022
4.1335655
.249328
4.0107809
1.03061
.970296
0
76
10
.244743
4.0859130
.252420
3.9616518
1.03137
.969588
50
20
.247563
4.0393804
.255517
3.9136420
1.03213
.968872
40
30
.250380
3.9939292
.258618
3.8667131
1.03290
.968148
30
40
.253195
3.9495224
.261723
3.8208281
1.03363
.967415
20
50
.256008
3.9061250
.264834
3.7759519
1.03447
.966675
10
15
0
.258819
3.8637033
.267949
3.7320508
1.03528
.965926
0
75
10
.261628
3.8222251 '
.271069
3.6890927
1.03609
.965169
50
20
.264434
3.7816596
.274195
3.6470467
1.03691
•.964404
40
30
.267238
3.7419775
.277325
3.6058835
1.03774
.963630
30
40
.270040
3.7031506
.280460
3.5655749
1.03858
.962849
20
50
.272840
3.6651518
.283600
3.5260938
1.03944
.962059
10
16
0
.275637
3.6279553
.286745
3.4874144
1.04030
.961262
0
74
10
.278432
3.5915363
.289896
3.4495120
1.04117
.960456
50
20
.281225
3.5558710
.293052
3.4123626
1.04206
.959642
40
30
.284015
3.5209365
.296214
3.3759434
1.04295
.958820
30
40
.286803
3.4867110
.299380
3.3402325
1.04385
.957990
20
50
.289589
3.4531735
.302553
3.3052091
1.04477
.957151
10
17
0
.292372
3.4203036
.305731
3.2708526
1.04569
,956305
0
78
10
.295152
3.3880820
.308914
3.2371438
1.04663
.955450
50
20
.297930
3.3564900
.312104
3.2040638
1.04757
.954588
40
30
.300706
3.3255095
.315299
3.1715948
1.04853
.953717
30
40
.303479
3.2951234
.318500
3.1397194
1.04950
.952838
20
50
.306249
3.2653149
.321707
3.1084210
1.05047
.951951
10
18
0
.309017
3.2360680
.324920
3.0776835
1.05146
.951057
0
72
10
.311782
3.2073673
.328139
3.0474915
1.05246
.950154
50
20
.314545
3.1791978
.331364
3.0178301
1.05347
.949243
40
30
.317305
3.1515453
.334595
2.9886850
1.05449
.948324
30
40
.320062
3.1243959
.337833
2.9600422
1.05552
.947397
20
50
.322816
3.0977363
.341077
2.9318885
1.05657
.946462
10
19
o'
.325568
3.0715535
.344328
2.9042109
1.05762
.945519
0
71
10
.328317
3.0458352
.347585
2.8769970
1.05869
.944568
40
20
.331063
3.0205693
.350848
2.8502349
1.05976
.943609
40
70
e
/
Cosine
Secant
Cotangent
Tangent
Cosecant
Sine
/
0
For functions from 70° 40' to 77° 0' read from bottom of table upward.
Digiti
zed by G00gk
46 WEIGHTS AND MEASURES
Natural Sines, Cosecants, Tangents, etc. — Continued
•
/
Sine
Cosecant
Tangent
Cotangent
Secant
Cosine
'
o
19
30
.333807
2.9957443
.354119
2.8239129
1.06085
.942641
30
40
.336547
2.9713490
.357396
2.7980198
1.06195
.941666
20
50
.339285
2.9473724
.360680
2.7725448
1.06306
.940684
10
20
0
.342020
2.9238044
.363970
2.7474774
1.06418
.939693
0
70
10
.344752
2.9006346
.367268
2.7228076
1.06531
.938694
50
20
.347481
2.8778532
.370573
2.6985254
1.06645
.937687
40
30
.350207
2.8554510
.373885
2.6746215
1.06761
.936672
30
40
.352931
2.8334185
.377204
2.6510867
1.06878
.935650
20
50
.355651
2.8117471
.380530
2.6279121
1.06995
.934619
10
21
0
.358368
2.7904281
.383864
2.6050891
1.07115
.933580
0
00
10
.361082
2.7694532
.387205
2.5826094
1.07235
.932534
50
20
.363793
2.7488144
.390554
2.5604649
1.07356
.931480
40
30
.366501
2.7285038
.393911
2.5386479
1.07479
.930418
30
40,
.369206
.371908
2.7085139
.397275
2.5171507
1.07602
.929348
20
50
2.6888374
.400647
2.4959661
1.07727
.928270
10
22
0
.374607
2.6694672
.404026
2.4750869
1.07853
.927184
0
08
10
.377302
2.6503962
.407414
2.4545061
1.07981
.926090
50
20
.379994
2.6316180
.410810
2.4342172
1.08109
.924989
40
30
.382683
2.6131259
.414214
2.4142136
1.08239
.923880
30
40
.385369
2.5949137
.417626
2.3944889
1.08370
.922762
20
50
.388052
2.5769753
.421046
2.3750372
1.08503
.921638
10
23
0
.390731
2.5593047
.424475
2.3558524
1.08636
920505
0
07
10
.393407
2.5418961
.427912
2.3369287
1.08771
.919364
50
20
.396080
2.5247440
.431358
2.3182606
1.08907
.918216
40
30
.398749
2.5078428
.434812
2.2998425
1.09044
.917060
30
40
.401415
2.4911874
.438276
2.2816693
1.09183
.915896
20
50
.404078
2.4747726
.441748
2.2637357
1.09323
.914725
10
24
0
.406737
2.4585933
.445229
2.2460368
1.09464
.913545
0
00
10
.409392
2.4426448
.448719
2.2285676
1.09606
.912358
50
20
.412045
2.4269222
.452218
2.2113234
1.09750
.911164
40
30
.414693
2.4114210
.455726
2.1942997
1.09895
.909961
30
40
.417338
2.3961367
.459244
2.1774920
1.10041
.908751
20
50
.419980
2.3810650
.462771
2.1608958
1.10189
.907533
10
25
0
.422618
2.3662016
.466308
2.1445069
1.10338
.906308
0
05
10
.425253
2.3515424
.469854
2.1283213
1.10488
.905075
50
20
.427884
2.3370833
.473410
2 1123348
1.10640
.903834
40
30
.430511
2.3228205
.476976
2.0965436
1.10793
.902585
30
40
.433135
2.3087501
.480551
2.0809438
1.10947
.901329
20
50
.435755
2.2948685
.484137
2.0655318
1.11103
.900065
10
04
e
'
Cosine
Secant
Cotangent
Tangent
Cosecant
Sine
•
e
For functions from 64° 10' to 70* 30' read from bottom of table upward.
Digiti
zed by G00gk
SINES, COSECANTS, TANGENTS, ETC. 47
Natural Sines, Cosecants, Tangents, etc. — Continued
•
/
Sine
Cosecant
Tangent
Cotangent
Secant
Cosine
'
•
26
0
.438371
2.2811720
.487793
2.0503038
1.11260
.898794
0
64
10
.440984
2.2676571
.491339
2.0352565
1.11419
.897515
50
20
.443593
2.2543204
.494955
2.0203862
1.11579
.896229
40
30
.446198
2.2411585
.498582
2.0056897
1.11740
.894934
30
40
.448799
2.2281681
.502219
1.9911637
1.11903
.893633
20
50
.451397
2.2153460
.505867
1.9768050
1.12067
.892323
10
27
0
.453990
2.2026893
.509525
1.9626105
1.12233
.891007
0
63
10
.456580
2.1901947
.513195
1.9485772
1.12400
.889682
50
20
.459166
2.1778595
.516876
1.9347020
1.12568
.888350
40
30
.461749
2.1656806
.520567
1.9209821
1.12738
.887011
30
40
.464327
2.1536553
.524270
1.9074147
1.12910
.885664
20
50
.466901
2.1417808
.527984
1.8939971
1.13083
.884309
10
28
0
.469472
2.1300545
.531709
1.8807265
1.13257
.882948
0
62
10
.472038
2.1184737
.535547
1.8676003
1.13433
.881578
50
20
.474600
2.1070359
.539195
1.8546159
1.13610
.880201
40
30
.477159
2.0957385
.542956
1.8417409
1.13789
.878817
30
40
.479713
2.0845792
.546728
1.8290628
1.13970
.877425
20
50
.482263
2.0735556
.550515
1.8164892
1.14152
.876026
10
29
0
.484810
2.0626653
.554309
1.8040478
1.14335
.874620
0
61
10
.487352
2.0519061
.558118
1.7917362
1.14521
.873206
50
20
.489890
2.0412757
.561939
1.7795524
1.14707
.871784
40
30
.492424
2.0307720
.565773
1.7674940
1.14896
.870356
30
40
.494953
2.0203929
.569619
1.7555590
1.15085
.868920
20
50
.497479
2.0101362
.573478
1.7437453
1.15277
.867476
10
30
0
.500000
2.0000000
.577350
1.7320508
1.15470
.866025
0
60
10
.502517
1.9899822
.581235
1.7204736
1.15665
.864567
50
20
.505030
1.9800810
.585134
1.7090116
1.15861
.863102
40
30
.507538
1.9702944
.589045
1.6976631
1.16059
.861629
30
40
.510043
1.9606206
.592970
1.6864261
1.16259
.860149
20
50
.512543
1.9510577
.596908
1.6752988
1.16460
.858662
10
31
0
.515038
1.9416040
.600861
1.6642795
1.16663
.857167
0
59
10
.517529
1.9322578
.604827
1.6533663
1.16868
.855665
50
20
.520016
1.9230173
.608807
1.6425576
1.17075
.854156
40
30
.522499
1.9138809
.612801
1.6318517
1.17283
.852640
30
40
.524977
1.9048469
.616809
1.6212469
1.17493
.851117
20
50
.527450
1.8959138
.620832
1.6107417
1.17704
.849586
10
32
0
.529919
1.8870799
.624869
1.6003345
1.17918
.848048
0
58
10
.532384
1.8783438
.628921
1.5900238
1.18133
.846503
50
20
.534844
1.8697040
.632988
1.5798079
1.18350
.844951
40
57
e
t
Cosine
Secant
Cotangent
Tangent
Cosecant
Sine
'
o
For functions from 57° 40' to 64° 0' read from bottom of table upward.
Digitized by VJiOOQLC
48 WEIGHTS AND MEASURES
Natural Sines, Cosecants, Tangents, etc. — Continued
•
'
Sine
Cosecant
Tangent
Cotangent
Secant
Cosine
'
o
32
30
.537300
1.8611590
.637079
1.5696856
1.18569
.843391
30
40
.539751
1.8527073
.641167
1.5596552
1.18790
.841825
20
50
.542197
1.8443476
.645280
1.5497155
1.19012
.840251
10
33
0
.544639
1.8360785
.649408
1.5398650
1.19236
.838671
0
57
10
.547076
1.8278985
.653531
1.5301025
1.19463
.837083
50
20
.549509
1.8198065
.657710
1.5204261
1.19691
.835488
40
30
.551937
1.8118010
.661886
1.6108352
1.19920
.833886
30
40
.554360
1.8038809
.666077
1.5013282
1.20152
.832277
20
50
.556779
1.7960449
.670285
1.4919039
1.20386
.830661
10
34
0
.559193
1.7882916
.674509
1.4825610
1.20622
.829038
0
56
10
.561602
1.7806201
.678749
1.4732983
1.20859
.827407
50
20
.564007
1.7730290
.683007
1.4641147
1.21099
.825770
40
30
.566406
1.7655173
.687281
1.4550090
1.21341
.824126
30
40
.568801
1.7580837
.691573
1.4459801
1.21584
.822475
20
50
.571191
1.7507273
.695881
1.4370268
1.21830
.820817
10
35
0
.673576
1.7434468
.700208
1.4281480
1.22077
.819152
0
55
10
.575957
1.7362413
.704552
1.4193427
1.22327
.817480
50
20
.578332
1.7291096
.708913
1.4106098
1.22579
.815801
40
30
.580703
1.7220508
.713293
1.4019483
1.22833
.814116
30
40
.583069
1.7150639
.717691
1.3933571
1.23089
.812423
20
50
.585429
1.7081478
.722108
1.3848355
1.23347
.810723
10
36
0
.587785
1.7013016
.726643
1.3763810
1.23607
.809017
0
54
10
.590136
1.6945244
.730996
1.3679959
1.23869
.807304
50
20
.592482
1.6878151
.735469
1.3596764
1.24134
.805584
40
30
.594823
1.6811730
.739961
1.3514224
1.24400
.803857
30
40
.597159
1.6745970
.744472
1.3432331
1.24669
.802123
20
50
.599489
1.6680864
.749003
1.3351075
1.24940
.800383
10
37
0
.601815
1.6616401
.753554
1.3270448
1.25214
.798636
0
53
10
.604136
1.6552575
.758125
1.3190441
1.25489
.796882
50
20
.606451
1.6489376
.762716
1.3111046
1.25767
.795121
40
30
.608761
1.6426796
.767627
1.3032254
1.26047
.793353
30
40
.611067
1.6364828
.771959
1.2954057
1.26330
.791579
20
50
.613367
1.6303462
.776612
1.2876447
1.26615
.789798
10
38
0
.615661
1.6242692
.781286
1.2799416
1.26902
.788011
0
52
10
.617951
1.6182510
.785981
1.2*722957
1.27191
.786217
50
20
.620235
1.6122908
.790698
1.2647062
1.27483
.784416
40
30
.622515
1.6063879
.795436
1.2571723
1.27778
.782608
30
40
.624789
1.6005416
.800196
1.2496933
1.28075
.780794
20
50
.627057
1.5947511
.804080
1.2422685
1.28374
.778973
10
51
e
$
Cosine
Secant
Cotangent
Tangent
Cosecant
Sine
$
e
For functions from 51° 10' to 57° 30' read from bottom of table upward.
Digitized by VJiOOQLC
SINES, COSECANTS, TANGENTS, ETC. 49
Natural Sines, Cosecants, Tangents, etc. — Continued
e
/
Sine
Cosecant
Tangent
Cotangent
Secant
Cosine 1 '
«
30
0
.829320
1.5890157
.809784
1.2348072
1.28676
.777146
0
51
10
.631578
1.5833318
.814612
1.2275786
1.28980
.775312
50
20
.633831
1.5777077
.819463
1.2203121
1.29287
.773472
40
30
.636078
1.5721337
.824336
1.2130970
1.29597
.771625
30
40
.638320
1.5666121
.829234
1.2059327
1.29909
.769771
20
50
.640557
1.5611424
.834155
1.1988184
1.30223
.767911
10
40
0
.642788
1.5557238
.839100
1.1917536
1.30541
.766044
0
50
10
.645013
1.5503558
.844069
1.1847376
1.30861
.764171
50
20
.647233
1.5450378
.849062
1.1777698
1.31183
.762292
40
30
.640448
1.5397690
.854081
1.1708496
1.31509
.760406
30
40
.651657
1.5345491
.859124
1.1639763
1.31837
.758514
20
50
.653861
1.5293773
.864193
1.1571495
1.32168
.756615
10
41
0
.656050
1.5242531
.869287
1.1503684
1.32501
.754710
0
40
10
.658252
1.5191759
.874407
1.1436326
1.32838
.752798
50
20
.660439
1.5141452
.879553
1.1369414
1.33177
.750880
40
30
.662620
1.5091605
'.884725
1.1302944
1.33519
.748956
30
40
.664796
1.5042211
.889924
1.1236909
1.33864
.747025
20
50
.666966
1.4993267
.895151
1.1171305
1.34212
.745088
10
42
0
.669131
1.4944765
.900404
1.1106125
1.34563
743145
0
48
10
.671289
1.4896703
.905685
1.1041365
1.34917
.741195
50
20
.673443
1.4849073
.910994
1.0977020
1.35274
.739239
40
30
.675590
1.4801872
.916331
1.0913085
1.35634
.737277
30
40
.677732
1.4755095
.921697
1.0849554
1.35997
.735309
20
50
.679868
1.4708736
.927091
1.0786423
1.36363
.733335
10
43
0
.681998
1.4662792
.932515
1.0723687
1.36733
.731354
0
47
10
.684123
1.4617257
.937968
1.0661341
1.37105
.729367
50
20
.686242
1.4572127
.943451
1.0599381
1.37481
.727374
40
30
.688355
1.4527397
.948965
1.0537801
1.37860
.725374
30
40
.690462
1.4483063
.954508
1.0476598
1.38242
.723369
20
50
.692563
1.4439120
.960083
1.0415767
1.38628
.721357
10
44
0
.694658
1.4395565
.965689
1.0355303
1.39016
.719340
0
46
10
.696748
1.4352393
.971326
1.0295203
1.39409
.717316
50
20
.698832
1.4309602
.976996
1.0235461
1.39804
.715286
40
30
.700909
1.4267182
.982697
1.0176074
1.40203
.713251
30
40
.702981
1.4225134
.988432
1.0117088
1.40606
.711209
20
50
.705047
1.4183454
.994199
1.0058348
1.41012
.709161
10
45
0
.707107
1.4142136
1.000000
1.0000000
1.41421
.707107
0
45
•
*
Cosine
Secant
Cotangent
Tangent
Cosecant
Sine
•
«
For functions from 45° 0' to 51° 0' read from bottom of table upward.
Digiti
zed by G00gk
60
WEIGHTS AND MEASURES
Moment of Inertia, Radius op Gyration and Center op Gravity
Moment of Inertia. — The moment of inertia of a section is the
sum of the products of each elementary area of the section times the
Square of its distance from an axis through the center of gravity
of the section or other axis assumed for purposes of computation.
Thus suppose an area A be divided into a large number of small
areas a, and that each has its own radius r, from the assumed axis,
then the moment of inertia / — ^ a r2. See table on page 52.
Radius of Gyration. — This is equal to the square root of the
quotient of the moment of inertia divided by the area of the section,
expressed, R — A/ I /A. The radius of gyration is used in column
calculations. The unbraced length of the section divided by the radius
of gyration is termed the ratio of slenderness. See Columns.
Center of Gravity of a body is that point about which, if sus-
pended, all the parts would be in equilibrium, that is, there would
be no tendency to rotate. If a body is suspended at its center
of gravity, it will be in equilibrium in all positions. If it is sus-
pended at any other point it will swing into a position such that
its center of gravity is vertically below its point of suspension.
To Find the Center of Gravity of a Cross Section of a Ship. —
First find the moment of the area about an end ordinate by taking
each ordinate and multiplying it by its distance from the end
ordinate. These products put through Simpson's rule will give the
moment of the figure about the end ordinate, which moment divided
by the area will give the distance of the center of gravity of the
area from the end ordinate.
Example. A section of a steamer has half breadths beginning at the load water
line, 4.86, 4.20, 3.40, 2.42, 1 .33, .70 and .10 ft. spaced 2 ft. apart. Find how
far from the load water line the center of gravity of the section is.
Number
of
Length
Simpson's
Multi-
Function
of
Number of
Intervals
Products
for
Ordinate
Ordinate
pliers
Ordinates
from No. 1
Moments
1
4.86
1
4.86
0
.00
2
4.20
4
16.80
1
16.80
3
3.40
2
6.80
2
13.60
4
2.42
4
9.68
3
29.04
5
1.33
2
2.66
4
10.64
6
.70
4
2.80
5
14.00
7
.10
1
1.00
6
6.00
44.60
90.08
Digitized
by Google
CENTER OF GRAVITY
51
Half area from load water line = X X 2 X 44 . 60.
Moment of half area about load water line = X X 2 X 2 X 90.08.
Distance center of gravity of section below load water line
X X 2 X 2 X 90.08
» 4.03 ft.
HX2 X44.60
If the total area or total moment was desired multiply by 2.
To Find the Center of Gravity of a Water Plane from its Middle
Ordinate. — Lay off a table thus:
Number of
Ordinate
Length of
Ordinate
Simpson's
Multipliers
Functions of
Ordinates
Number of
Intervals
from Middle
Ordinate
Products for
Moments
1
. IX
2
3
4
5
.10
2.48
4.86
8.75
11.16
12.12
12.25
12.25
11.92
11.12
9.10
6.80
3.90
X
2
IX
4
2
4
2
4
2
4
IX
2
X
.05
4.96
7.29
35.00
22.32
48.48
24.50
49.00
23.84
44.48
13.65
13.60,
1.95
5
*X
4
3
2
1
0
1
2
3
4
4H
5
.25
22.32
29.16
105.00
44.64
48.48.
6
249.85
7
8
9
10
n
49.00
47.68
133.44
54.60
61.20
9.75
.
289.12
355.67
Ordinates 9.5 ft. apart
355.67 -249.85 - 105.82
Distance center of gravity aft of the middle ordinate
105.82 X9.5
289.12
= 3.47 ft.
Or let
A = sum of functions of ordinates
B — sum of products of moments forward of the middle ordinate
C = sum of products of moments aft of the middle ordinate
subtract~the smaller sum of products of moments from the larger
and let the difference be D.
I Then the distance of the center of gravity from the middle ordinate
_ D X distance the ordinates are apart
A
and whether the distance is forward or aft depends on whether B
or C is the largest.
Digitized by VjiOOQLC
52
WEIGHTS AND MEASURES
Properties of Various Sections
Sections
Area of Section
A
Distance from Neutral
Axis to Extremities
of Section
x and xi
— *-Hfr
T
T
1
a
-I
1
£
hfrgH
»»-«i>
T
a = -7z=.70Ta
y Google
PROPERTIES OF VARIOUS SECTIONS 53
Properties of Various Sections — Continued
Moment of Inertia
1
Section Modulus
XI
Radius of Gyration
a*
12
a»
•
JL-=.2Wa
Vl2
**
3
a»
3
'*-"*.
a«-*«
fia
12
. , f*F.
12
r-^==.118a«
6V 2
-4==. 280a
V12
- uigiiizsucirvjOOS?
54 WEIGHTS AND MEASURES
Properties of Various Sections — Continued
Sections
£
T
1
Area of Section
A
bd
Distance from Neutral
Axis to L
, of Section
x and ii
bd
» = d
Y-&
V
1
6d-bidi
i
bd
d
bd
Vb» + d»
y Google
PROPERTIES OF VARIOUS SECTIONS 55
Properties of Various Sections — Continued
Moment of Inertia
I
Section Modulus
8--L
Radius of Gyration
12
fad>
6
-7==.280d
V12
fa*
3
fad>
3
1 •
\/3
i
b#-Wdi»
6d
-
bd«-bidi«
12
/ b#-bidi'
y 12 (bd - udi)
fatf
\ !
; ' i
i b»d«
bd
6(b» + d»)
i 6Vb»-fd« 5
V 6 (b» + dJ)
y Google
66 WEIGHTS AND MEASURES
Properties op Various Sections — Continued
Sections
Area of Section
A
bd
M
2
Distance from Neutral
Axis to Extremities
of Section
xandxt
dcosa-4-bsun
d
2d
*=F
bd
2
* = d
i=.w#
x»"-o
y Google
^
PROPERTIES OF VARIOUS SECTIONS 57
Properties op Various Suctions — Continued
Moment of Inertia
I
~(d»ecrfa + b«Bin««)
Section Modulus
8 = 1
db/d»coe»
6 V dooft
» + b ana ;
Radius of Gyration
-A
/■
'd» cqb» a + b» an* a
12
36
b#
34
Vl8
= .236d
b#
12
12
vr
>.408d
^=.049*
-w=[
<XWd»
by Google
58 WEIGHTS AND MEASURES
Properties of Various Sections— Continued
Sections
W—6 M
Area of Section
A
»r(d»-di»)
= .785(d*-di»)
8 "
Distance from Neutral
Axis to Extremities
of Section
x and xi
«-!*-■«"
i = ^L-4Ld=>288d
b + bi
. d
-|d"tan.30°=.866d«
b + 2bi d^
s b + bi *3
bi + 2b ^
= b + bi *3
Digitized by VJ \J\J V LV^
PROPERTIES OF VARIOUS SECTIONS 59
Properties op Various Sections — Continued
i
Moment of Inertia
r (»-&«)
64
= M9(&-&x<)
frr*-64
1152v '
d>s.007d>
b» + 4bh + bi»
36(b + b») '
A rd»(l + 2coB«30o)1
12 I 4cos*30* J
= .06d«
Section Moadulus
S-I
32 d "-098 d
frr»-64
102 (3» - 4)
. d>=.024d»
b» + 4bb» + hi*
12 (bi + 2b)
. d*
A. rd(l + 2cos»30°)]
6 I 4 co* 30° J
= .12d»
Radius of Gyration
Vd» + df
4
Vr»r«~64
12fT
. d=.132d
6(b+bi)y
2(b* + 4bbi + bi«)
4 ops 30* Y
2 coe» 30°
3
= .2Md
y Google
60
WEIGHTS AND MEASURES.
Properties of Various Sections — Continued
Area of Section
A
Distance from Neutral
Axia to Extremities
of Section
x and zi
|-d»tan.30°=-.8fl6d*
= 2^W=577d
/T\
2d»tnn.22*,= .828d»
i
z
^=.785 bd
»"?T
y Google
PROPERTIES OF VARIOUS SECTIONS 61
Properties of Various Sections — Continued
Moment of Inertia
I
a rd»(i + 2<x»>ao*)i
12 L 4 corf 30° J
- .06*
8ection Modulus
8 = 1
A. rd(t + 2ocW30*)1
6 L 4cos30° J
= .104d»
Radius of Gyration
-«4
d /l + 2 coB» 30°
4 cob 80° y 3
= .264d
A, rd»(l + 2oos«22n'|
12 L 4cos»22*° J
= .055d*
A rd (1 +-2 ooa* 22m
6 L 4ooB22i* J
= .10W»
4oos22i
/1JH200
• V 3
= .257d
eoe»22iB
vbd>
04
>bd«
32
= .098bd»
jiyiu^uyCoOgle
62 WEIGHTS AND MEASURES
Properties of Various Sections — Continued
Sections
Area of Section
A
td + 2b' (s + nO
Distance from Neutral
Axis to Extremities
of Section
x and xi
d
td + 2b' (a + nO
td + b' (a + nO
Digitized by VJ vJvJ V LV^
PROPERTIES OF VARIOUS SECTIONS 63
Properties of Various Sections — Continued
Moment of Inertia
I
Second Modulus
s.I
zt
Radius of Gyration
-A
£[„*_£*_„]
21
d
-A
i[b»(d-M + W
+ i(b.-f)]
21
b
•ys_ ■
![!*-£*.-»]
1
21
d
■ .-/?'•
y Google
64
WEIGHTS AND MEASURES
Properties of Various Sections — Continued
Sections
*££
13
^
&
i
1"
■* u — r
I- — </■
ILfc
Area of Section
A
td + b'(a + nO
bd - h (b - t)
bd - h (b - t)
Distance from Neutral
Axis to Extremities
of Section
x and xi
x = [b% + ^+.f (b-t)»|
(b + 2t)] 4- A I
xi = b — x
-4
Digitized by
Google
PROPERTIES OF VARIOUS SECTIONS 65
Properties of Various Sections — Continued
Moment of Inertia
I
Section Moduli*
XI
Radius of Gyration
-VI
y[2sb» + lt»+!.(b«-t«)]
-A*
I
-vl
•
bd» - h> (b - t)
6d
bd» - h> (b - t)
12
/ M»-h»(b-t)
y i2[bd-h(b-t)]
2sb> + ht*
6b
2sb> + bt*
12
/ 2sb» + ht>
y 12[bd-h(b-t)]
66 WEIGHTS AND MEASURES
Properties op Various Sections — Continued
Sections
K^
1
ls>
JL
<*»
*
-j
Area of Section
A
bd - n (b - t)
bd-h(b-t)
Distance from Neutral
Axis to Extremities
of Section
x and xi
d
_ 2b*i + W
X"~ 2A
xi = b — x
td + s (b - t)
Digitized by Vji\J vJ V LV^
PROPERTIES OF VARIOUS SECTIONS 67
Properties op Various Sections — Continued
Moment of Inertia
I
bd» - h» (b - t)
12
2sb» + ht»
- Ax«
td» + a» 0> - t)
12
Section Modulus
8-1
bd» - h» (b - t)
6d
I
b -x
td» -f a» (b - t) r
6d
Radius of Gyration
/
bd» - h» (b - t)
12[bd-h(b-t)l
v-
td» + af (b - t)
12 (td + s (b - t) 1
y Google
68
WEIGHTS AND MEASURES
Properties of Various Sections — Continued
Sections
ta
i
a
Area of Section
A
be + ht
Distance from Neutral
Axis to Extremities
of Section
x and xi
d»t + s»(b-t)
X~ 2A
n = d — x
J« "<? >>
bs + ht + bis
td« + s«(b-t) + g(bi-t)(2d-B)
2A
xi = d — x
iWH
bs +
h (t + 1.)
3bs> + 3th (d + s) + h (ti - 1) (h + 3s) |
6A
xi = d — x
y Google
PROPERTIES OF VARIOUS SECTIONS 69
Properties of Various Sections— Continued
Moment of Inertia
I
to* + bx* - (b - t) (x - b)«
Section Modulus
fl-i-
I
d- x
Radius of Gyration
Vi
/■
to» + bx» - (b - t) (x - g)»
3(bs + ht)
bx» + bix,» - (b - t) (x - s)»
3
(fa - t) (Xl - 8)»
3
I
d-x
bx» -f DM* - (b - t) (x - g)»
3 (be + ht + bis)
(fa - t) (xi - 8K| H
3(be + ht + bi8)J
4bB» + h»(3t + ti)
12
-A(X-8)»
I
d -x
^
y Google
SECTION II
STRENGTH OF MATERIALS
Stress is the general term denoting the force or resistance which
acts between bodies or parts of a body when under the influence
of a load. It is measured either in tons or lb. per square inch of
sectional area.
Strain is the change in form produced by stress.
Tension. — A body is said to be under tension when the action
of a force tends to extend it in the direction of its length. Tensile
strength is the resistance per unit of surface which the molecular
fibers oppose to separation.
Compression. — A body is said to be under compression when
the action of a force tends to compress it in the direction of its
length.
Shearing Strain. — A body is said to be subjected to a shearing
strain in any cross section when the distorting force acts in the
plane of that cross section.
Elasticity is the power to resist permanent deformation. The
elastic limit is the limit of stress that can be withstood without
permanent elongation. The continued application of a stress in
excess of the original elastic limit will eventually cause fracture
owing to fatigue of the material.
The modulus or coefficient of elasticity is the ratio between the
stresses and corresponding strains for a given material. If I be the
strain or increase per unit length of a material subjected to tensile
stress, and p the unit stress producing the elongation, the modulus
of elasticity E is equal to -y-.
Modulus of rupture is the strain at which the molecular fibers
cease to hold together.
70
ULTIMATE STRENGTH
71
Ultimate Strength. — The load producing rupture gives the
strength of a material, .and it is usual to denote the strength by
the expression ^-r. — . In this expression the original cross
cross section
section is taken before it has been decreased by the stress.
Strength op Materials*
(Stresses per Square Inch)
Metals and Alloys
Streams in Thousands of Pounds
Ten-
sion
Ulti-
Elastic
Limit
Corn-
Ulti-
mate
Bend-
ing
UlS-
ing
Ulti-
Modulus
of Elastic-
ity. Lb.
Elong-
ation
%
Aluminum —
cast
bars, sheets
wire annealed
Aluminum bronze —
5%toZ^%al
10% al
Brass—
17% zinc
30% zinc...
cast, common
wire annealed
Bronze — v
8% tin
13% tin
24% tin
gun metal —
9% copper, l%tin..
manganese, cast —
10% tin, 2%mang...
manganese, rolled —
10%tin,2%mang...
phosphorus, cast —
9% tin, l%phos
phosphorus, wire —
9% tin, l%phos
tobin, cast —
38% zinc, VA% tin,
HIead
tobin, rolled —
38% zinc, 1H% tin,
Mlead
Copper —
cast
plates, rods, bolts
wire annealed
Delta Metal-
cast f 55-60% copper
plates! 38-40% zinc
bars 1 2- 4%iron
wire I 1- 2%tin
15
24-28
20-35
75
85-100
32.6
28.1
18-24
50
28.5
29 4
22
25-55
60
100
50
100
66
80
25
32-35
36
45
68
85
100
6.5
12-14
14
8.2
19
20
22
10
30
80
24
6
10
10
120
30
42
53
114
125
40
32
23
26
20
34.5
32
22
12
30
11,000,000
9,000,000
14,000,000
10,000,000
10,000,000
4,500,000
10,000,000
15,666,000
26.7
20.7
5.5
3.3
♦Carnegie Steel Co. Handbook
Digitized
by Google
72
STRENGTH OF MATERIALS
Strength op Materials — Continued
(Stresses per Square Inch)
Stresses in
Thousands of Pounds
Modulus
of Elastic-
ity, Lb.
Metals and Alloys
Ten-
sion
Ulti-
mate
Elastic
Limit
Com-
pression
Ulti-
mate
Bend-
ing
Ulti-
mate
Shear-
ing
Ulti-
mate
Elong-
ation,
%
Gold—
20
30
15-18
18-24
27-35
1.8
2.2-2.5
3.3
53
32
40
58-68
55-65
52-62
55-65
45-55
60
70
80
55-70
85-100
65-110
120
80
3.5-1.6
48
50
80
60
4-6
7-16
4
6
15-20
H tens.
Vt tens,
^tens.
J^tens.
Htens.
27
31.5
36
33
55
50
40-70
60
40
1.5-1.8
26
27
27'
4
80
46'
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
"6'
tensile
tensile
18
30
25-33
30
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
tensile
"4'
tensile
tensile
7
18-20
'46'
% tens.
^tens.
% tens.
%tens.
%tens.
%tens.
%tens.
\i tens.
%tens.
%tens.
^i tens.
|tens.
§ tens.
8,000,000
12,000,000
1,000,000
1,000,000
720,000
29,000,000
29,000,000
29,000,000
29,000,000
29,000,000
29,000,000
29,000,000
29,000,000
29,000,000
29,000,000
29.000,000
iooo.'obb
28,000,000
28,000,000
15,000,000
25,000,000
13,000,000
Iron, Cast —
Lead —
cast
Platinum wire —
Steel—
Bhip
25.9-
boiler —
fire box
22.1
27.3-
flange plates
• rivets —
ships
23.
28.8-
24.2
27.3-
boilers
23.
27.3-
castings —
soft
23.
22.
18.
hard
15.
concrete bars, plain, struc-
tural grade
concrete bars cold twisted
nickel, 3.25% nickel,
shapes, plates, bars .
springs, untempered.. .
wire unannealed. ......'
25.4-
20.
5.
17.6-
15.
Tin, cast
Wrought Iron —
wire
unannealed
annealed
Zinc —
cast
rolled sheets
Die
itized by V
jOOQk
WORKING STRESS
73
Strength of Materials — Continued
(Stresses in Pounds per Square Inch)
Ultimate Average Stresses
Modulus
of
Elasticity
Safe Working Stresses
Building Materials
Com-
pression
Ten-
sion
Bend-
ing
Com-
pression
Bear-
ing
Shear-
ing
Stone—
bluestone
12,000
12.000
8,000
5,000
10,000
10,000
6,000
30.000
700
5,000
1,700
1.200
500
1,200
1,200
800
150
3,000
200
3,000
70
2,500
1,600
1,500
1,200
5,000
600
3,000
7,000,000
7,000,000
7.000,000
3,000.000
14,000,000
8,000,000
1,200
1,200
800
500
1,000
420
350
280
140
280
168
1,200
1,200
800
500
1,000
600
500
400
250
500
300
200
(granite
200
limestone — marble.-. .
sandstone
150
150
slate
175
Brick-
common, good
pressed and paving. . .
Masonry —
granite
limestone— bluestone .
sandstone
nibble
concrete 1, 2H, 5
brick, common
Miscellaneous —
glass, common
plaster ,
terracotta ,
::::
Concrete —
1, 2^, 5, hard stone. .
soft stone
cinders
Rxintorced Concrete— Safe Working Stresses
Elastic Modulus—
2,000,000 if ultimate compression is up to 2,200.
1. 2H. 5, means 1 part
cement, 2\£ sand, 5
stone
2J500i000 if ultimate compression is over 2,200.
3,000,000 if ultimate compression is over 2,900.
Compression —
22.5% of ultimate compression on piers or columns of
lengths not exceeding 12 ins.
Bearing—
32.5% of ultimate compression on surfaces of at least
twice the loaded area.
Shearing —
2% of ultimate compression, horizontal bars.
3% for reinforcement with bent up bars.
6% for thoroughly reinforced webs.
Bond—
4% of ultimate compression for plain bars.
2% for drawn wire.
Working Stress: Factor of Safety. — The stress allowed under
working conditions is only a fraction of the ultimate strength and
is called the working stress. The factor of safety is that number
which is divided into the ultimate strength to arrive at the working
stress. Thus working stress = -= — r-^ — ! ef ~ . The factor of
factor of safety
safety depends to a great extent on the nature of the forces acting
and on the material.
Digitized by VjiOOQIC
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BEAMS
Factors of Safety
75
Material
Steady
Load
Load Varying
from Zero to
Maximum
in One
Direction
Load Varying
from Zero to
Maximum
in Both
Directions
Suddenly
Varying
Loads
and
Shocks
Cast iron
6
4
5
8
15
15
10
6
6
10
20
20
15
8
8
15
25
25
20
Wrought iron
Steel
12
12
Wood
' 20
Brick
30
Stone
30
Hemp rope for running rigging factor of safety 8-9
Steel rope for running rigging factor of safety 6-7
Steel rope for standing rigging factor of safety 5-6
Beams
The strength of a beam depends on the form of its cross section,
how the load is distributed and on the way the beam is supported.
In the majority of cases in ship construction beams are fixed at
both ends, although some fixed at one end occur in fittings as bitts,
davits, etc.
+ a-
iwbi ffdxi cth
</->
«i
**
Figure 11
When a beam is loaded there is always compression in the top-
most fibers and tension in the bottom. There is a position in the
cross section at which the fibers are neither in compression nor
tension, and this position is the neutral axis of the section. Thus
the neutral axis passes through the center of gravity of every cross
section and is at right angles to the direction in which the load acts.
nvJ^v^
76
STRENGTH OF MATERIALS
The algebraic sum of the moments of the external forces about
any point in a beam is the bending moment at that point; that is,
the bending moment at any point is the moment about that point
of either reaction minus the sum of the moments of the intermediate
loads about the same point. The bending moments at several points
on the beam shown in Fig. 11 are: at Wi = Ria, at W% = Ri (a + b)
- Wi b, at Wz = Ri (a + b + c) - [W* c + Wi (b + c)]. Various
methods of loading are shown under Bending Moments of Beams.
Fibers which are at equal distances from the neutral axis will
be deformed to the same extent. The resistance to bending is the
combination of the resistances to tension and compression. Thus
let
bending moment
distance from the outermost fiber to the neutral axis
moment of inertia of the section
safe or allowable unit fiber stress in pounds per square
inch
M
V
I
V -
Then -^
M
or p
My
or M =
V
The moment of resistance Mx of
and — the section modulus = a,
y
a beam is the sum of the moments about the neutral axis of all the
stresses in the fibers composing the section. Hence Mi — 8 p; that
is, the safe resisting moment is equal to the safe fiber stress multi-
plied by the resistance.
Figure 12
The reactions or supporting forces of a beam must equal the
load on it. If the load on a beam is uniformly distributed, applied
at the center of the span or symmetrically placed and of equal
amount on each side of the center, the reactions Ri and Ri will each
be equal to one half the load. When the load is not symmetrically
placed, the reactions are found by the principle of moments.
•
le
BEAMS 71
Suppose a beam as in Fig. 12 is supporting loads Wi, W* and Wi,
I the span or distance between the reactions Ri and R*t a, bt and c
the distances from the reaction Ri to the loads W\, W2 and Wi.
Then the righOhand reaction & = <^X«)+(TT,X 6)+qT.X c).
Hence to find the reaction at either support, multiply each load by
its distance from the other support, and divide the sum of these
products by the distance between supports. Since the sum of the
reactions must equal the sum of the loads, if one reaction is found
the other can be obtained by subtracting the known one from the
sum of the loads.
The loads and reactions, besides causing bending or. flexure,
create shearing stresses in the beam by their opposing tendency;
that is, as the reactions act upward, and the loads downward,
the effect is to shear the fibers of the beam vertically. At any
section, the shear is equal to either reaction minus the sum of the
loads between that reaction and the section considered. The
maximum shear is always equal to the greatest reaction. For a
single beam with a uniformly distributed load, the maximum shear
is at the supports, and is equal to one half the load or the reac-
tion; the shear changes at every point of the loaded length, the min-
imum shear being zero at the center of the span. The maximum
shear in a simple beam having a single load (omitting weight of
beam) concentrated at the center is equal to one half the load,
and is uniform throughout the beam. When a beam supports sev-
eral concentrated loads, changes in the amount of shear occur only
at the points where the loads are applied.
Examples. What is the greatest safe load that can be lifted by a boat davit
having an outreach of 5 ft. and a diameter of 7 ins. The davit is of wrought iron.
This is a case of a beain with one end fixed and with the load at the other, hence
the bending moment is M = W X L, where L is the outreach of the davit or 5 ft.
From the beam formula M = —
V
p — safe load for wrought iron = 5 tons
L « 5 ft. X 12 ins. « 60 ins.
/ "•
= section modulus = S
V
d ■■ diameter = 7 ins.
W XL = v X^-
V
,*d*
p X S 5 tons X "32
Hence W = 2^_ — = — = 2\£ tons. See also formula for
L 60
Boat Davit.
Digitized
by Google
78 STRENGTH OF MATERIALS
Find the safe resisting mpment of a Northern yellow-pine beam 10 ins. wide by
12 ins. deep, using a factor of safety of 4.
Here Afi = 8 p.
The section modulus S (see table) is ~ or 10 X 12 X 12 » 240
o o
The modulus of rupture for Northern yellow pine is 6,000 lb.
The desired factor of safety being 4, the safe unit stress p = ~ — — 1,500 lb.
4
Substituting these values in the formula, safe resisting moment M\ = 5p, we
have 1,500 X 240 = 360,000 as the safe resisting moment of the beam section in
inch pounds.
[Above paragraph contains abstracts from Building Trade Handbook, Int. School
of Correspondence.]
Beams Under Various Loading Conditions
[From Pocket Companion, Carnegie Steel Co.]
Bending Moments and Deflections
Notation in Formulae
A = area of section in square inches
y = distance from center line of gravity to extreme fiber in inches
/ = moment of inertia about center line of gravity in inches*
8 = section modulus = — in inches8
V _
r = radius of gyration = if ~a m inches
/ = bending stress in extreme fiber in pounds per square inch
E = modulus of elasticity in pounds per square inch
I = length of section in inches
d — depth of section in inches
b =* breadth of section in inches
t * = thickness of section in inches
W, Wi, Wi = superimposed loads supported by beam in pounds
w = superimposed loads in pounds per unit length or area
W max. = maximum safe load at point given in pounds
R, 'Ri = reactions at points of support in pounds
Af, Mi, M% = bending moments at points given in inch pounds
M max. = maximum bending moment in inch pounds
D, Di = deflections at points given in inches
D max. — maximum deflection at point given in inches
• Digitized by VjiOOQ 1C
CANTILEVER BEAM 79
1. Cantilever Beam. — Concentrated load at free end.
r*v*
Ri (max. shear)
M, distance x
M max. at R\
IF max.
D max.
W
Wz
Wl
Li
i
3E I
2. Cantilever Beam. — Uniformly distributed load.
Ri (max. shear)
M, distances
IT max.
D max.
- W
Wx*
21
2fs
I
Wl*
8E I
3. Cantilever- Beam. — Load increasing uniformly to fixed end.
Ri (max. shear)
M, distances]
M max. at R\
IP max.
D max.
Digiti
w
Wx*
30
Wl
3
3/j
I
Wl*
15EI
zed by GOOgk
80 STRENGTH OF MATERIALS
4. Beam Supported at Ends. — Concentrated load near one end.
R (max. shear if 6 > a)
Wb
I
Ri (max. shear if a > 6)
_ Wa
I
M, distance x
Wbx
I
M max. at point of load
Wab
I
IF max.
fsl
ab
D max.
=
Wab(a + 26) V3o (o +26)
27 E II
5. Beam Supported at Ends.— ^Concentrated load at center.
•
R (max. shear) = Ri
W
2
M, distance x
Wx
2
M max. at point of load
IF*
4 '
IF max.
4/8
I
D max.
" 48#7
6. Beam Supported at Ends. — Two unsymmetrical concentrated
loads.
R (max. shear if o < 6) =
$6 62
Hi
M , distance a = Ra =
Mi max. distance b (6 >a) = /fr6 =
^ /J _l_ IA
"2T. 0+«-*>
IF
Ma, distance 3=#a; — ■— (3— a)
TF max. (6 > o) =
2J/a
6 (* + a - 6)
Digitized by VjiOOQ LC
BEAM SUPPORTED AT ENDS 81
.7. Beam Supported at Ends. — Two symmetrical loads.
R (max. shear) = Rx
^r ' "\. Mm/r* M* distance x
W
2
Wx
2
M max. at and between loads
Wa
2
|*0 O^ '
W max.
D max.
8. Beam Supported at Ends. — Three concentrated loads
- '**
-iTWl «"-«')
t 1 >
■u
Wb + Wtbi + Wtb*
I
10
**
Rx « Wa + Wl ai + ^ a>
3f at W = Ra
M max. if TF = or > J2
Af at TFi = ftoi - TT(oi - a)
Af max. ifJFi + TF = ffor > ft
Af max. if Wx + TT« = ft, or > ft,
Af at TPj = fta* - W (at - a) -
Wx (jot - ax)
M max. if JFa = ft, or > ft
9. Beam Supported at Ends.— Uniformly distributed load,
w
R (max shear) - Rx = ~-
M, distance x
-?0-f)
Af max. at center =
IF max.
Z> max.
8
8 fa
I
6WP
384J57 J
Digitized by VjOOQLC
82
STRENGTH OF MATERIALS
10. Beam Supported at Ends. — Load increasing uniformly to one
end.
2W
Rt (max. shear) — — ^~
M, distance x
Wx/ _xf\
- 3 V1 l)
x* a- * *V3 2 Wl
M max. distance — - — — — ■=.
TPmax.
D max.
9V3
27 fa
2W3*
.013044 WP
EI
11. Beam Supported at Ends. — Load decreasing uniformly to
center.
R (max. shear) = R\
M, distance x
W
2
w /l x , 2x*\
M max. distance i
IF max.
D max.
IFJ
12
12/8
I
3 TTP
320^7
12. Beam Supported at Ends. — Load increasing uniformly to
center.
R (max. shear) = Ri
M, distance x =
M max. distance \
Wmax.
D max.
W
2
^•(i-£)
TfJ
6/a
Digitized
byGoOgl
60^7
BEAM SUPPORTED AT ENDS
83
13. Beam Supported at Ends. — Uniform load partially distributed.
R (max. shear if a < c) =
W (2c 4- b)
21
W (2a + b)
2L
M, distance x — a or <a = Rx
Ri
Mi, distance x > a
■■ Rx -
W(x - o)»
26
^xzp ^
Jfj, distance x > (a + b) *=
_ TF (2x - 2a - b)
** 2
Jf max. distance o + -= =
W (2c + b) [4«i + b (2c + b)]
IF max.
8ft /g
(2c + 6) \4al + b (2c + b)]
14. Beam Supported at Ends. — Uniform load partially discon-
tinuous.
u-4-/
# (max. shear if W > Wi) =
W (21 - a) +Wic
21
Wi (21 - c) + Wa
Ri
21
M, distance x < a = R x r —
Mi, distance x > a —
Rx -
W(2x -a)
M max. distance x ■»
2 TFo/ - Fa* + Wi Ca
2 WI
and Wa > Wic
W max.
= 2W
2/a
15. Beam Continuous over Two Supports. — Two exterior sym-
metrical loads.
T
Ri
R (max. shear)
M, distance x
M max. from R to Ri
TFmax.
u
Wa (3oZ - 4a!)
W
2
Wx
2
Wa
2
2fs
Dt distance a
Di, distance
I
12 E I
Wa (l - 2<r.)g
2 16 tf /
Digitized by VJiOOQ 1C
84 STRENGTH OF MATERIALS
16. Beam Continuous over Two Supports. — Uniformly distributed
load.
w
B — Ri = -=t max. shear
Wa
I
M, distance x ••
rmT\2a)
TF(x* -Ix + oJ)
21
-4a)
|«— | / A Mi at J2 and «i - -^f-
21 _
max. if a > I (Vi - i)
„ . . W (I - 4a)
ift at center = -
max. if a < I ( VT - *)
Wimax. „*M±
max. if a > I ( V* — i)
JF.max. -y^ii-
J — 4a _
max. if a < I ( V* - §)
Deflection. — Formula for deflection is given in section on Beams
under Various Loading Conditions. The depth of rolled steel beams
should not be less than ix of the span, and plate girders not less
than t^.
Columns
It was formerly assumed that the strength of a column depended
largely on the condition of its ends. Many engineers now make no
difference in their calculations for round-ended, pin-ended and
square-ended 'columns. Usual factor of safety 5 or 6.
Below are formulae for calculating the strength of columns:*
(1) Steel Columns.
P — total centrally applied load on column in pounds, in-
cluding proper allowance for impact
A = minimum area of cross sections in square inches
I = total length of column in inches
r = its least radius of gyration
Then for steel columns of ordinary length where l/r does not ex-
ceed 120 for the principal members, or 150 for the secondary mem-
bers, and where P/A does not exceed 14,000 lb. \
P = A (l6,000 - 70 y)
♦Formulae from Electrical Engineer's Handbook.
Digitized by LiOOQ 1C
COLUMNS 85
(2) Cast Iron Columns.
d =» diameter of circular column or shortest side 01 rect-
angular column in inches
-j- not to exceed 40
a
P - A (6,100 - 32 -j)
(3) Timber Columns.
Long-leaf yellow pine P = A |1300 f 1 - ^\ 1
Short-leaf pine and spruce P = 4 1 1100 (l - ^J I
Or if p is taken as the ultimate load in pounds per square inch,
then the safe load for a given section may be obtained by multiply-
ing the value of p as found from the formulae given below,41 by the
area of the section and dividing by the factor of safety. .
Steel column with both ends fixed or resting on flat supports.
50000
1 +,
36000 r»
Steel column with one end fixed and resting on flat supports
and the other end round or hinged.
50000
V - n —
1 +;
24000 r*
Steel column with both ends round or hinged.
50000
V -
1 +
18000 r*
Cast iron columns solid with both ends fixed or resting on flat
supports, d = diameter of column.
80000
V - —
i+ p
800 d*
* From Machinery's Handbook.
Digitized by LiOOQ LC
86
STRENGTH OF MATERIALS
Columns of H and I Sections*
(Safe loads in thousands of lbs.)
Allowable fiber stress per square inch, 13,000 lb. for lengths of
80 radii or under; reduced for lengths over 60 radii.
Depth and Weight of Sections
Effective
Length
H
I
in
Feet
8-in.
34 1b.
perfi.
6-in.
5-in.
4-in.
15-in.
12-in.
10-in.
9-in.
8-in.
7-in.
6-in.
5-in.
4-in.
23.8
lb.
18.7
lb.
13.6
lb.
42 1b.
per ft.
31H
lb.
25
lb.
21
lb.
18
lb.
15
lb.
12M
lb.
9H
lb.
7}4
lb.
• 2
3
130.
130.
130.
130.
130.
130.
130.
130.
91.
.91.
91.
91.
91.
91.
71.5
71.5
71.5
71.5
71.5
52.
52.
52.
162.2
162.2
162.2
162.2
120.4
120.4
120.4
120.4
95.8
95.8
95.8
82.
82.
82.
69.3
69.3
69.3
57.5
57.5
46.9
46.9
37.3
37.3
33.3
22.7
28.7
28.5
4
56.8
50.
43.2
36.4
44.5
38.5
32.5
26.5
24.
5
50.7
45.7
40.6
35.6
30.5
94.4
85.3
76.2
67.1
58.
77.8
69.4
61.
52.6
44.2
63.2
55.6
48.
40.4
35.
31.2
27.4
23.6
19.8
16.
19.5
6
153.9
140.1
126.2
112.3
98.5
109.9
98.9
87.9
76.9
65.9
15.2
7
66.
60.5
55.
49.5
44.
38.5
18.8
16.1
13.5
10.8
13.
8
9
86.7
80.9
75.1
69.3
63.5
57.7
51.9
30.3
26.9
23.5
20.1
16.7
13.3
22.9
19.9
16.8
13.8
10.8
10.8
8.5
10
125.8
119.4
113.
106.6
100.2
93.8
87.3
80.9
74.5
26.7
24.2
21.7
19.2
16.6
14.1
50.2
45.7
41.1
36.5
32.
27.4
22.9
40.
35.8
31.5
27.3
23.1
18.9
11
12
86.
79.
72.1
65.2
58.2
51.3
44.4
37.4
59.9
54.4
48.9
43.4
37.9
32.4
26.9
13
14
35.8
33.
30.3
27.5
24.8
22.
19.3
16.5
15
16
17
18
47.6
44.7
41.8
38.9
36.
33.1
19
20
69.
65.8
Area in
sq. ins.
10.
7.
5.5
4.
12.48
9.26
7.37
6.31
5.33
4.42
3.61
2.87
2.21
Safe load values above, upper zigzag line are for ratios of — not
over 60, those between the zigzag lines are for ratios up to 120
and those below lower zigzag line for ratios over 200.
* Carnegie Steel Co. Pocket Companion.
Digiti
zed by G00gk
SQUARE WOODEN COLUMNS
87
Cast iron column, hollow, round, both ends fixed or resting on
flat supports, d = outside diameter of column.
80000
P "" Hi—
1 +
800 cP
Cast iron column, hollow, square, with both ends fixed or resting
on flat supports, S = outside dimension of square.
80000
p- —
1 +
1000 &
For square wood columns with flat supports, the side of the
square being S,
5000
V *—
1 +
250 /S*
Square Wooden Columns
(Safe loads in thousands of pounds)
America Railway Engineering Association Formulae
Long-Leaf Pine — White Oak — 1,300 f 1 — — ^J
Length
Feet
Side of Square (Inches)
10
12
16
18
20
10
11
12
14
16
18
20
15.6
15.6
14.6
13.5
12.5
11.4
10.4
35.1
34.3
32.8
31.2
29.6
28.1
25.0
62.4
62.4
60.3
58.2
54.1
49.9
45.8
41.6
97.5
93.6
88.4
83.2
78.0
140.4
137.3
131.0
124.8
191.1
189.3
182.0
249. C
315.9
390.0
~
88
STRENGTH OF MATERIALS
Round Wooden Columns
(Safe loads in thousands of pounds)
Long Leaf Pine— White Oak— 1,300 (l - ^gj
Length
Diameter (Inches)
Feet
4
6
8
10
12
14
16
18
20
12.3
27.6
49.0
76.6
110.3
150.1
196.0
248.1
5
6
7
12.3
11.4
10.6
9.8
9.0
8.2
8
9
27.0
25.7
24.5
23.3
22.1
19.6
10
11
12
49.0
47.4
45.7
42.5
39.2
35.9
32.7
14
73.5-
69.4
65.3
61.3
16
107.8
102.9
98.0
18
20
148.7
142.9
306.3
Loads above horizontal lines are the maximum allowable safe
loads.
Safe Load on Standard Wrought Iron Pipe Columns
(For table of sizes see page 508.)
Both Ends Fixed Factor of Safety = 6 In Tons of 2000 lb.
Size
Length of Column — Feet
Pipe
Inches
8
10
12
14
16
18
20
2
2.0
1.8
1.4
2V2
3,35
2.8
2.4
2.1
3
4.8
4.3
3.8
3.36
3.08
VA
6.07
5.52
5.1
4.47
4.02
4
7.67
7.1
6.56
6.02
5.4
4«
9.32
8.69
8.16
7.52
6.98
5
10.53
9.93
9.33
8.6
8.0
6
14.6
13.82
13.03
12.37
11.75
7
18.58
17.9
17.2
16.5
15.76
8
23.13
22.45
21.7
20.85
20.11
JUUVlL
TORSIONAL STRESSES
89
Safe Load on Strong and Extra Strong Wrought Iron Pipb
Columns
Both Ends Fixed Factor of Safety « 6 In Tons of 2000 lb.
Strong
Size
Length of Column — Feet
Pipe
Inches
8
10
12
14
16
18
20
2
2H
3
3^
4
5
6
7
8
3
36
3.10
4.93
6.78
9.05
11.56
12.23
2.46
4.41
6.21
8.43
10.94
11.62
15.94
23.03
29.24
33.84
ski
5.64
7.80
10.30
10.97
15.27
22.18
28.52
33.34
5.10
7.18
9.52
10.18
14.40
21.26
27.73
32.53
i'.w
6.58
8.88
9.64
13.67
20.54
26.90
31.63
\2.M
19.80
25.73
30.68
Extra Strong
2
6.04
5.57
4.43
2H
8.79
7.86
6.80
6.12
3
13.19
12.08
10.97
9.92
8.94
3H
16.55
15.41
14.26
13.13
12.05
4
21.24
20.11
18.92
17.50
16.32
4^
25.29
24.03
22.69
21.05
19.94
5
29.58
28.35
26.73
25.38
24.11
6
42.79
41.21
39.50
38.16
36.80
7
56.23
54.85
53.34
51.73
49.49
8
65.66
64.70
63.11
61.37
59.52
Torsional Stresses. — To find the safe torsional load of a circular
shaft.
T = twisting moment
d\ = outside diameter of the shaft
d\ = inside diameter of the shaft
/ = safe stress per square inch of section
. dt* - a\*
Then for a hollow shaft T - jzf
di
If the shaft is solid d2 = 0and!T = ^/(i8
Digiti
zed by G00gk
90 STRENGTH OF MATERIALS
Springs. — To determine the size of steel wire for wire springs,
Let D s = mean diameter in inches of coii.
W = total load in pounds
d = diameter of round or side of square steel wire in inches
c = 11,000
Then d = 3|/^^
To obtain the number of free coils N when the above data are
known and the compression C is decided on, use the formula
_ Cd'a
WD*
where d = size in sixteenths of an inch
a = 26 for round (British Admiralty) or 22 (Board of
Trade)
= 32 for square (British Admiralty) or 30 (Board of
Trade)
Formula for Calculating Strength of Tubes, Pipes and Thin
Cylinders. — The one (Barlow's) commonly used assumes that the
elasticity of the material at the different circumferential fibers
will have their diameters increased in such a manner that the
length of the tube is unaltered by the internal pressure.
Let t = thickness of wall in inches
p = internal pressure in pounds per square inch
S = allowable tensile strength in pounds per square inch
D = outside diameter in inches
n = safety factor as based on ultimate strength
rm. P 2* J DP
Then -g- - jj * ~ -2S
_2St _ D P
P - ~D S - ~2t
S = for butt-welded steel pipe
n
50000
n
60000
n
28000
for lap-welded steel pipe
for seamless steel tubes
for wrought iron pipe
n
In the above, the thickness of the wall t is assumed to be small
ioogle
WROUGHT IRON TUBES
91
compared to the diameter. The thicknesses of thin pipes under
the same internal pressure should increase directly as their diameters.
A cylinder under exterior pressure is theoretically in a similar
condition to one under internal pressure as long as it remains a
true circle in cross section.
BUBSTING AND COLLAPSING PRESSURES OP WROUGHT IRON TUBES
[Lukens Iron & Steel Co.]
Burst-
Collaps-
Burst-
Collaps-
Thick-
ing
ing
External
Thick-
ing
ing
Exter-
Per
Per
Per
Per
nal Dia.
ness
Sq. Inch of
Sq. Inch of
Dia.
ness
Sq. Inch of
Sq. Inch of
Internal
External
Internal
External
Surface
Surface
Surface
Surface
(Ins.)
(Ins.)
(Lb.)
(Lb.)
(Ins.)
(Ins.)
(Lb.)
(Lb.)
1.25
.083
7700
6500
3.25
.12
4000
2700
1.375
.083
6900
5800
3.5
.134
4200
2700
1.5
.083
6200
5200
3.75
.134
3900
2400
1.625
.083
5700
4700'
4.
.134
3600
2100
1.75
.083
5300
4300
4.25
.134
2400
1900
1.875
.083
4900
4000
4.5
.134
3200
1700
2.
.083
4500
3700
4.75
- .134
3000
1600
2.125
.095
4900
3800
5.
.134
2800
1400
2.25
.095
4600
3600
5.25
.148
3000
1400
2.5
.109
4800
3600
5.5
.148
2800
1200
2.75
.109
4300
3100
5.75
.148
2700
1100
3.
.12
4400
3000
6.
.148
2600
1000
Strengths of Various Fittings. —
Let d — diameter of iron in inches
Then working load of a hook = -.- tons
working load of a ring bolt =» 2d2 tons
working load of eye bolt = 5cP tons
working load of a straight shackle = 3d2
working load of a bow shackle = 2l/faP
Suppose in a chain having a shackle, hook and ring bolt, it is de-
sired to have all the parts of approximately the same strength,
assuming the link of the chain as 1, then the eye of eye bolt = 1%
shackle = 1%
ringbolt = 1%
hook at back =3}^
See also Chain table.
[Abstracts from Naval Constructor, G. Simpson.]
Digitized by LiOOQ 1C
92
STRENGTH OF MATERIALS
The strength of a bitt or bollard can be calculated as a beam
supported at one end and loaded at the other. Usually a thickness
of 1}4 his. is sufficient, but the outside diameter depends on the
size of the chain or hawser that will be used. For steel wire hawsers,
bitts should not be less in diameter than four times the circumference
of the hawser.
Riding Bitts or Bollards
Dia. in Inches
Dia. of Cable in Inches
16
m
18
m
20
i%
22
IK
24
2
26
2H
28
2M
As to the working load for rivets
allow 1 ton for each % inch rivet
2 tons for each J£ inch rivet
S}4 tons for each 1 inch rivet
The breaking stress in tons of a rivet in single shear is about
25 times the sectional area A of the rivet, and in double shear 50
times.
If S — safe shearing stress on a rivet in tons per square inch
W = working load on a rivet
A — sectional area of the rivet in square inches
Then W — S A f or single shear, or
— 1% S A for double shear
See also section on Rivets and Riveting. Bolts may be similarly
calculated.
Digiti
zed by G00gk
BOLTS 93
Shearing and Tensile Strength of Bolts
Area
Shearing Strength
Tensile Strength
Ultimate
CroeB Sections
Safe Loads
Safe Loads
Tensile and
Shearing Strain
at 50,000 lb.
du:
of
Bolt
Full Bolt
Root of Thd.
Root of Thd.
Per Square Inch
Bolt
Root
of
Thread
7500
lb. per
Sq.In.
10000
lb. per
Sq.In
7500
lb. per
Sq. In.
10000
lb. per
Sq.In.
10000
lb. per
Sq.In.
12500
lb. per
Sq.In.
Full
Bolt
Root
of
Thread
sq. m.
sq. in.
lb.
lb.
lb.
lb.
lb.
lb.
lb.
lb.
H
P.
A
.049
.076
.110
.150
.026
.045
.067
.093
368
575
828
1127
491
767
1104
1503
202
341
509
700
269
454
678
933
269
454
678
933
3*36
568
848
1166
2455
3835
5520
7515
1345
2270
3390
4665
A
Vs
H
%
.196
.248
.306
.441
.601
.125
.162
.201
.302
.419
1472
1861
2301
3314
4510
1963
2485
3068
4418
6013
943
1216
1514
2265
3145
1257
1621
2018
3020
4193
1257
1621
2018
3020
4193
1571
2026
2523
3775
5241
9815
12425
15340
22090
30065
6285
8105
10090
15100
20965
1
m
.785
.994
1.227
1.484
.551
.693
.889
1.054
5891
7455
9204
11137
7854
9940
12272
14849
4133
5198
6674
7906
5510
6931
8899
10541
5510
6931
8899
10541
6888
8664
11124
13176
39270
49700
61360
74245
27550
34655
44495
52705
1 767
2.073
2.405
2.761
1.293
1.514
1.744
2.049
13253
15554
18040
20709
17671
20739
24053
27612
9704
11362
13081
15368
12938
15149
17441
20490
12938
15149
17441
20490
16173
18936
21801
25613
88355
103695
120265
138060
64690
75745
87205
102450
2
2H
2M
3.141
3.976
4.908
5.939
2.300
3.021
3.716
4.619
23562
29821
36815
44547
31416
39761
49087
59396
17251
22660
27872
34647
23001
30213
37163
46196
23001
30213
37163
46196
28751
37766
46454
57745
157080
198805
245435
296980
115005
151065
185815
230980
3
3tf
3H
3^
7.068
8.295
9.621
11.044
5.427
6.509
7.549
8.641
53015
62219
72158
82835
70686
82958
96211
110447
40708
48819
56618
64809
54277
65092
75491
86412
54277
65092
75491
86412
67846
81365
94364
108015
353430
414790
481055
552235
271385
325460
377455
432060
4
4*
4H
4N
12.366
14.186
15.904
17.720
9.992
11.330
12.740
14.220
94248
106397
119282
132904
125664
141863
159043
177205
74947
84977
95554
106654
99929
113302
127405
142205
99929
113302
127405
142205
124911
141628
159256
177756
628320
709315
795215
886025
499645
566510
637025
711025
5
5V£
5«
19.635
21.647
23.758
25.967
15.765
17.574
19.267
21.262
147263
162356
178187
194754
196350
216475
237583
259672
118244
131809
144509
159465
157659
175745
192678
212620
157659
175745
192678
212620
197074
219681
240848
265775
981750
1082375
1187915
1298360
788295
878725
963390
1063100
6
28.274
23.094
212057
282743
173210
230947
230947
288684
1413715
1154735
Google
94
STRENGTH OF MATERIALS
Tests of Hooks and Shackles
Experience has shown that the same brand of iron or steel will
not maintain the same tensile strength under various conditions.
The following tables give the results of tests of hooks from % in. to
3 ins. diameter and of shackles from 3^ in. to 3 ins. diameter/ the
figures being taken from the catalogue of the Boston & Lockport
Co., Boston, Mass. In the column "Size, Inches," the diameter
of the hook or shackle is meant. It is suggested that not more
than 20% of the tensile strength as given in Column 2 be reckoned
as the working load, and on this basis Column 4 is calculated.
Ordinarily the hook of a block is the first to give way, and when
heavy weights are to be handled, shackles are far superior to hooks.
By many tests it has been proven that flattening a hook adds from
12 to 15% to its ultimate strength. "
Tests of Hooks
[Boston & Lockport Co.]
In column Size, Inches, the diameter of the hook or shackle is meant.
Size, Inches
Tensile
Strength, Lb.
Description
of Fracture
Working Load in Lb.,
Based on 20% of
the Tensile Strength.
That is a Factor of
Safety of 5
%
1,040
1,^15
2,010
2,650
3,210
4,750
6,680
13,720
14,540
16,950
18,340
21,220
25,780
30,250
38,100
41,150
46,145
65,150
110,000
Straightened
the Hook
u
u
It
It
tt
ft
ft
tl
ft
tt
tt
tt
tt
ft
tf
ft
tf
tt
208
A
249
y2
402
&
530
y8
612
%
950
J4
1,336
1
2,744
m -
\\i
2,908
3,390
1%
3,668
\y2
4,244
\y,
5,156
1%
6,050
iu
7,620
2
8,230
2M
9,229
2XA
13,030
3
22,000
y Google
Tests op Shackles
Sise, Inches
Tensile
Strength, Lb.
Description
of Fracture
Working Load in Lb.,
Based on 20% of the
Tensile Strength
H
%
%
V*
l
IX
IK
W%
llA
IX
2
2H
2V2
3
15,400
20,500
22,700
40,100
66,380
68,900
78,900
105,900
121,850
126,700
150,600
170,500
230,200
260,500
280,600
498,000
Sheared
Shackle Pin
3,080
4,100
4,540
8,020
13,276
13,780
15,780
21,180
24,370
25,340
30,120
34,100
46,040
52,100
56,120
99,600
Weldless Eye Bolts
(Either plain or shoulder pattern)
Shank
Diameter Eye
Capacity, Net Tons
Maxi-
mum
Standard
Length
Safe
Average
Approx-
Diam-
Length
Under
in
Inside
Outside
Working
Load at
imate
eter
Stock
Load
Elastio
Breaking
Eye
Limit
Strain
X
IX
4M
1
m
.7
1.4
3.
A
IX
IX
1*
1H
1.
2.
4.
X
IX
*X
1A
2A
1.3
2.5
5.
A
W
m
1A
2A
1.5
3.
6.
X
W
±X
IX
2«
2.
4.
8.
X
2
5
IX
2*i
3.
6.
12.
X
2X
5
Itt
3M
3.5
7.
16.
l
2y2
5
1*1
3A
4.
8.
20.
1H
IX
5
2
4
5.
10.
23.
Hi
3
6
2A
4A
7.5
15.
33.
IX
3^
6
2X
5A
9.
18.
42.
IX
3X
6
2H ■
6A
11.
21.
53.
2
4
6
3M
6H
13.
25.
68.
2X
5
6
4
8A
16.
32.
85.
05
Drop Forged Hoist Hooks With Eye
(Capacity with plain shank the same)
Diameter of Eye
Ertreme Dimensions
Capacity, Net Tons
Average
Approximate
Safe
Load
Load
Inside
Outside
Length
Width
Working
Load
at
Elastic
Limit
Required to
Straighten
Out
X
IX
4H
2^
.5
.9
1.9
X
IX
m
3H
.6
1.2
2.3
1
2
5Vs
3H
.7
1.5.
3.
IX
2X
6A
3^
1.2
2.5
5.7
V4
2}4
■VA
4^
1.7
3.5
7.
1%
2X
7X
4%
5^
2.1
4.2
8.5
IX
3
8A
2.5
5.4
10.
m
ax
9A
6^
3.
6.2
13.
IX
VA
10^
6%
4.
8.
17.
2
4
11H
7J^
4.7
9.
19.
2%
4%
13
8}<
5.5
11.
26.
2H
5X
14K
9M
6.8
13.
32.
vx
VA
ViX
10K
8.
17.
35.
ZX
7.
l»H
13
11.
21.
48.
4
&X
22^
14%
20.
40.
80.
Iron Guy Shackles
Sise in
Inches of
Gov. Test
Maximum
Length
Width
Between
Eyes
Inches
Diameter
of Pin
Approximate
Weight
Shackle
Strength
Inside
of Each
(Diam. of
Iron in Bow)
in
Pounds
Inches
Inches
in
Pounds
H
10,890
IK
%
A
0.30
ft
15,200
VA
H
ti
0.48
18,390
VA
0.70
A
24,800
VA
H
0.90
X
33,400
2X
1A
X
1.40
X
43,400
3
i&
%
2.20
X
55,200
3^
\x
1
3.40
1
74,900
4
IX
IX
5.00
IX
90,200
4^
va
IX
6.80
IX
92,040
5
2
m
9.40
1%
94,100
VA
2%
m
12.20
IX
103,800
6
2X
w%
16.40
W%
155,542
6^
2A
m
19.00
IX
172,400
7
2X
VA
24.00
2
235,620
8
Wa.
2A
38.20
From J. H. Williams & Co., Brooklyn.
96
Digitized by
Google
TURNBUCKLES
97
TURNBUCKLES
Drop-forged, with hook and eye, shackle and eye, two eyes, two
hooks, two shackles, or hook and shackle.
Size Turn-
Amount
buckle
of
Length
and
Approxi-
Recom-
Take-up
Length
Pull to
Approxi-
Outside
mate
mended
Length
in the
Pull
mate
Diameter
Breaking
Working
Buckle
When
Weight
of
Strength
Load
Clear
Outside
Extended
Each
Thread
in Pounds
in Pounds
Between
in Inches
in
in Pounds
in
Heads
Inches
Inches
in Inches
H
1,350
270
4
4J£ •
12
.40
ft
2,250
450
4J*
5M
13H
.60
3,350
670
VA
6%
14
.90
S
4,650
930
5
VA
16J*
1.31
6,250
1,250
6
m
18M
1.87
A
8,100
1,620
7K
9
23H
3.00
H
10,000
2,000
sy2
103^
24^
3.69
*A
15,000
3,000
9X
llJi
27^
5.81
v%
21,000
4,200
10
12X
30M
8.$1
1
27,500
5,500
11
14
33
12.56
\y%
34,500
6,900
12
15H
39
17.00
Wa.
44,500
8,900
13
165*
40
25.00
m
52,500
10,500
14
18
50
36.00
1H
64,500
12,900
15
19M
51
40.00
W&
75,500
15,100
16
21
51^
48.00
l«
87,000
17,400
' 18
23
55H
52.00
W*
102,500
20,500
18
23
66
89.00
2
115,000
23,000
24
31
74
98.00
2H
132,500
26,500
24
31
2H
151,000
30,200
24
32
Formulae for Circular Davits. —
D
W
R =
a =
K -
diameter of each davit in inches
weight of boat with full complement of equipment and
persons (figured at 165 lb. each) plus weight of
tackle and blocks, all in pounds
radius of overhang of davit arm in inches
increase of W to take care of increase in stresses
when ship is listed 15°
fiber stress allowed in pounds per square inch
Then D
-?■
1W XRX (1 +a)
XK
Digiti
zed by G00gk
STRENGTH OF MATERIALS
The average values given below substituted in the above formula
will give a handy equation for calculating the diameter of the davit.
• a = 25 and K = 12000
Hence D - .0812 %/~W~~XR
For davits of structural steel their dimensions must give the
same strength as round bar davits as figured with the above formula.
Lloyd's rule for boat davits.
L = length of boat
B = beam of boat
D = depth of boat
H = height of davit above its uppermost point of support
S = spread
AU the above dimensions are in feet.
C = constant = 82 when the davit is of wrought iron and
of sufficient strength to safely lower the boat fully
equipped and carrying the maximum number of
passengers
d = diameter of davit in inches
-v1-
IL X B X D (H + 4S)
C
Davits may be calculated as beams, fixed at one end and loaded
at the other. See also section on Anchor Davits.
Stresses in Cranes, Derricks, and Shear Poles. — The stresses
in any member can be found graphically. Thus in Fig. 13 lay off
^Bwro^sar
Figure 13
Digiti
zed by G00gk
CRANES, DERRICKS, SHEAR POLES
99
the distance p to any scale, say 1 inch = 1,000 lb., it representing
the downward force or weight of the load, and draw a parallelo-
gram with the sides b t parallel to B and T so that p is the diagonal.
By scaling t the tension in the tie T is obtained and similarly the
compression b in the brace. The above also applies to Fig. 14.
Figure 14
In a guyed crane or derrick as Fig. 15 the strain in B is
PXB
A1
A1 being that portion of the vertical included between B and T
wherever T may be attached to A. If T is attached to B below its
Figure 15
K^AV^/^^WWiUIWw
Digiti
zed by G00gk
100
STRENGTH OF MATERIALS
extremity, there may be in addition a bending strain B due to a
tendency to turn about the point of attachment of T as a fulcrum.
The strain in T may be calculated by the principle of moments.
The moment of P is P X c The moment of the strain on T is
P X c
T X dt therefore the strain on T is — . As d decreases the
strain on T increases.
The strain on the guy rope G is calculated by the principle of
moments. The moment of the load about the bottom of the mast
is P X c. If the guy is horizontal the strain in it is F and its
P X c
moment is F X /, and F — — 7 — . If it is inclined, the moment
is the strain G X the perpendicular distance of the line of its direc-
P Xc
tion or g, and G
The guy rope having the least strain is
the horizontal one F, and the strain in G = strain in F X secant of
the angle between F and G. As G is made more nearly vertical g
decreases and the strain increases.
Another case is where the tie T is not perpendicular to A1, or
the post A may be omitted and T extended to the ground. The
parallelogram of forces may be applied and the equations,
D y (P D y D
(1) tension in T = — jr — and (2) compression in B = — — — ,hold.
Figure 16
Shear poles with guys. See Fig. 16. First assume that the two
masts act as one placed at B D and the two guys as one at A B.
Digitized by VJiOOQlC
RIVETS AND RiyETING
101
Calculate the strain in A B and B I) as in the previous case. Mul-
tiply half the strain in A B (or B D) by the secant of half the angle
the two masts or guys make with each other to find the strain in
each mast or guy.
(From Mech. Eng'rs Pocket Book. W. Kent)
RIVETS AND RIVETING
Different types of rivets are shown in Fig, 17. Pan- and button-
head rivets % hich in diameter or over have coned or swelled necks
for punched plates, and straight necks for drilled. The advantage
of swelled-neck rivets is that the diameter of the punched hole
on the die side is always slightly larger than on the punched side.
In assembling the plates are reversed, and thus with swelled-neck
rivets the holes are completely filled.
//ecrc/±
u u
o a o
_^"«* nee* I
A
9 9 £
Figure 17.— Rivet Heads and Points.
A = pan head. B = snap or button head, makes a neater appearance than pan
head. C = flush or countersunk flat head. D = countersunk raised head. E =
tap rivets. They are H of an inch greater diameter than is required for a plain
rivet to the same thiciaiess of plate or shape (Am. Bureau of Shipping Rutes).
F " snap point, proportions same as button head. G «= hammered point. H =*
countersunk point, proportions same for countersunk head.
Digiti
zed by G00gk
102 .. • - -STRENGTH. OF MATERIALS
Form of Rivet in outside plating
I* A/-
Proportions. — The proportions of
the heads and countersinks vary
Tapered neck to with the different classification
feguf in* *i£ societies. The U. S. Navy has its
tion to thick- own standard. There are thus no
universal standards, although
Lloyd's is doubtless adopted more
than any other for merchant work.
Below are Lloyd's proportions.
Countersink.
YZZ^
W-3-4
Diameter of Rivet, Ins.
A, Ins.
B, Ins.
y*
1
1A
H
%
It
y%
1
1A
\y%
1A
Countersink to extend through the whole thickness of the plate
when less than U/M or .7 ins. thick, when .7 ins. or above the coun-
tersink to extend through nine-tenths the thickness of the plate.
Lloyd's Rules for the. Diameter of Rivets
Thickness of plate in ins.
Diameter of rivet in ins.
.22 and
.34 and
.48 and
.66 and
.88 and
under .34
under .48
under .66
under .88
under 1.14
H
%
H
1
M
1.14 and
under 1.2
Lengths of Rivets for Ordering. — The length for ordering pan-
and button-head rivets is measured exclusive of the head; for
countersunk rivets and taps the ordered length includes the head
to the top of the countersink.
Digiti
zed by G00gk
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104
STRENGTH OF MATERIALS
Allowance for Points in Length of Rivets with Two Thick-
nesses Connected
Type of Point
Diameters of Rivets (Ins.)
H
H
H
Vi
i
1M
Countersunk
Hammered
Snap '.
H
1
7A
H
H
1H
k
i
H
IN
1M
Oval
The above allowances are based upon the average practice at
various U. S. Navy and private ship yards.
Rivets are usually shipped in kegs of 100 and 200 lb. In ordering
the diameter should be given first thus: }4 in. X 3 ins.
Materials. — To prevent galvanic action as far as possible iron
rivets should be used in iron plates, and steel in steel plates. It
is important that rivets have a high tensile strength and resistance
to shear. For specifications see Shipbuilding Materials.
Strength of Rivets. — The diameter of a rivet in inches for
single shear is given by the formula D =>i/ — ^ and in double
shear,
■•/s
or .707 D in single shear, where
D = diameter of rivet
c = factor of safety
F = shearing force
S = ultimate shearing strength of the material
Shearing and Tensile Strength of Steel Rivets in Pounds
per Square Inch
HIn.
Kin.
»/» In.
Kin.
Hln.
Shearing lb. per sq. in.
Tensile lb. per sq. in.
9,225
10,600
13,150
16,500
18,000
20,000
20,525
23,800
27,100
31,400
RIVETED JOINTS
105
Table of Ultimate Single Shearing Strength of Rivets
Diameter in Fractions (Ins)
Diameter
in Decimals
(Ins.)
Steel at
40,000 Lb.
Per Sq. Inch
Steel at
45,000 Lb.
Per Sq. Inch
x.
&
B:
it
.125
.187
.250
.312
.375
.437
.500
.562
.625
.687
.750
.812
.875
.937
.000
.062
.125
.187
.250
.312
.375
.437
.500
490
1,104
1,963
3,068
4,418
6,013
7,854
9,940
12,272
14,848
17,671
20,739
24,052
27,611
31,416
35,465
39,760
44,300
49,088
54,120
59,396
64,920
70,684
552
1,242
2,209
3,452
4,970
6,735
8,836
11,183
13,806
16,705
19,880
23,332
27,060
31,064
35,343
39,899
44,731
49,838
55,224
60,885
66,820
73,035
79,519
From Lukens Iron & Steel Co.
Riveted Joints. — A riveted joint may fail: (1) in the plate, by
tearing out or across from hole to hole; (2) in the rivet, by shearing;
and (3) in the plate or rivet, by a crushing of the material.
The failure of a joint by the tearing out of the plate in front
of the rivet may be prevented by placing the rivets at a proper
distance from the edge of the plate. This has been found to be
about one diameter in the clear or one and a half diameters of the
rivet from the edge of the plate to the center of the rivet. .
To determine the efficiency of a riveted joint, calculate the
ways it may fail, and the one giving the least result will show the
actual strength of the joint. If this equals Tr and T equals the
tensile strength of the solid plate then the efficiency of the joint
T
is 7=r which can be expressed as a percentage. Thus the average
relative strengths of joints in boilers are as follows:
Single riveted lap 55%
Digitized
by Google
106 STRENGTH OF MATERIALS
Double riveted lap 70%
Single riveted butt joint 65
Double riveted butt joint 75
Triple riveted butt joint 80
Quadruple riveted butt joint 85
From the following equations the unit stresses may be computed
when the other quantities are known, and by comparing them
with proper allowable unit stresses the degree of security of the
joint is estimated.
d — diameter of rivets T = tensile strength of plate
t =s thickness of plate C — crushing strength of rivets
p = pitch of rivets S = shearing strength of rivets
All dimensions are in inches, and stresses in pounds per square
inch.
Lap Joint Single RiveteU.
Resistance to tearing plate between rivets = t (p — d) T
Resistance to crushing of one rivet =■ tdC
Resistance to shearing of one rivet = Ji r d? S
Lap Joint Double Riveted.
Resistance to tearing plate between two rivets — t (p — d) T
Resistance to crushing of two rivets = 2 t d C
Resistance to shearing of two rivets
2*d*S
Butt Strap, Single Riveted, Two Cover Plates.
Resistance to tearing plate = t (p — d) T
Resistance to crushing of one rivet «* tdC
Resistance to shearing of one rivet
2ird*S
Butt Strap, Double Riveted, Two Cover Plates.
Resistance to tearing plate = t (p — d) T
Resistance to crushing of two rivets = 2 t d C
Resistance to shearing of two rivets
4«-«PS
The total shearing strength of a rivet in double shear is usually
taken as about 1.75 the strength in single shear.
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108
Number of Cone Head Rivets In 100 Pounds*
Scant Diameter
Length
Under
Head
Diameter
W
H" H* H" H" H
1H" IK
l
i«
ig
2
2H
2H
2%
i
2%
3
vt.
4
m
5
»:
6 ,
6H
7 .
1162
1075
1010
943
892
840
800
757
724
689
632
609
584
561
543
523
507
490
460
436
411
390
371
354
324
311
277
258
242
840
787
735
694
657
621
591
564
537
515
495
476
456
440
425
409
396
384
371
350
331
313
284
271
259
248
221
213
199
186
645
606
568
537
510
483
460
440
420
403
387
371
358
346
333
322
312
302
293
276
261
248
225
215
205
197
189
182
176
158
148
446
423
401
383
364
349
334
321
308
296
286
276
267
258
250
242
235
222
210
200
190
181
173
166
159
153
147
142
137
128
120
855
337
821
306
259
249
240
232
224
216
210
203
197
191
181
172
163
156
149
142
136
131
126
121
117
113
106
100
275
262
251
240
230
221
213
205
198
191
185
179
173
168
163
159
150
143
136
124
119
114
109
105
101
98
95
84
217
208
200
192
185
178
172
166
161
156
151
147
142
138
135
128
120
114
109
105
101
97
9-*
90
86
83
80
75
71
153
147
142
136
131
128
123
119
114
112
108
105
103
100
97
92
87
84
80
76
74
70
68
66
63
61
59
56
52
Exact
Dia.
107
104
100
97
93
90
87
85
82
80
78
75
74
71
68
65
62
Exact
Dia.
78.7
75.7
73.5
71.4
68.9
67.1
65.3
63.2
61.7
60.2
58.4
57.1
55.8
53.1
50.7
48.7
46.7
44.8
43.1
41.6
40.1
38.7
37.5
36.3
35.2
33.2
31.3
* Cone head sometimes called pan head. (Hoopes & Townsend, Phila., Pa.)
f All Rivets larger than one inch are made to exact diameter.
In rivet calculations, it is customary to disregard friction and to
proportion rivets to the entire stress to be transmitted. They must
be of sufficient size and number to resist shear and to afford such
bearing area as not to cause distortion of the metal at the rivet holes.
(Pocket Companion, Carnegie Steel Co.)
109
Digiti
zed by G00gk
Weight of Cone Head Rivets Per 100*
Scant Diameter
1 Length
Under
Diameter
Head
M"
A*
H*
tt*
K*
H*
H"
1'
IK"
IK"
«::::::::
8.6
11.9
15.5
t
t
9.3
12.7
16.5
. . . .
Exact
Exact
Dia.
Dia.
1
9.9
13.6
17.6
22.4
28.1
34.5
1H
10.6
14.4
18.6
23.6
29.6
36.3
1H
11.2
15.2
19.6
24.9
31.1
38.1
46
65
1H
11.9
16.1
20.7
26.1
32.6
39.8
48
68
93
1H
12.5
16.9
21.7
27.4
34.1
41.6
50
70
96
127
\y%
13.2
17.7
22.7
28.6
35.6
43.4
52
73
100
132
IK
m
13.8
18.6
23.8
29.9
37.1
45.1
54
76
103
136
14.5
19.4
24.8
31.1
38.6
46.9
56
78
107
140
2
15.1
20.2
25.8
32.4
40.1
48.7
58
81
110
145
2M
15.8
21.0
26.9
33.7
41.6
50.5
60
84
114
149
2H
16.4
21.9
27.9
34.9
43.1
52.2
62
87
117
153
2H
17.1
22.7
28.9
36.2
44.6
54.0
64
89
121
158
2J4
17.8
23.5
30.0
37.4
46.1
55.8
66
92
124
162
2%
18.4
24.4
31.0
38.7
47.6
57.5
68
95
128
166
»::::::::
19.1
25.2
32.0
39.9
49.1
59.3
70
97
132
171
19.7
26.0
33.1
41.2
50.6
61.1
72
100
135
175
3
20.4
26.9
34.1
42.5
52.1
62.8
74
103
139
179
3Ji
21.7
2$. 5
36.2
45.0
55.1
66.4
78
108
146
188
»::::::::
22.9
30.2
38.2
47.5
58.1
69.9
83
114
153
197
24.3
31.9
40.3
50.0
61.1
73.4
87
119
160
205
4
25.6
33.5
42.4
52.5.
64.1
77.0
91
124
167
214
4K
26.9
35.2
44.4
55.0
67.1
80.5
95
130
174
223
4**
4k
28.2
36.9
46.5
57.5
70.1
84.0
99
135
181
232
29.5
38.5
48.6
60.0
73.1
87.6
103
141
188
240
5
30.8
40.2
50.6
62.6
76.1
"91.1
107
146
195
249
5H
32.1
41.9
52.7
65.1
79.1
94.6
111
151
202
258
&K
33.4
43.5
54.8
67.6
82.1
98.2
115
157
209
266
34.7
45.2
56.8
70.1
85.1
101.7
120
162
216
275
6
36.0
46.8
58.9
72.6
88.1
105.2
124
167
223
284
6H
38.7
50.2
63.0
77.6
94.1
112.3
132
178
237
301
7
41.3
53.5
67.2
82.7
100.2
119.4
140
189
251
319
Weight of
Heads...
4.7
6.9
9.3
12.3
16.1
20.4
26
38
54
75
* Cone head sometimes called pan head. (Hoopes & Townsend, Phila., Pa.)
f All Rivets larger than one inch are made to exact diameter.
Boiler Rivet Steel.— The Am. Soc. for Testing Materials states
that the steel shall be made by the open hearth process. Chemical
composition, manganese .3O-.60%, phosphorus not over .04%, sul-
phur not over .045%. Tensile strength 45,000-60,000 lb. per sq.
in., yield point minimum .5 tensile strength/elongation in 8 ins. mini-
i per cent r2 4 — but not to exceed 30%.
* tens. str.
110
Digitized
by Google
SECTION III
SHIPBUILDING MATERIALS
IRON AND STEEL, NON-FERROUS METALS AND ALLOTS,
.WOOD, MISCELLANEOUS NON-METALLIC MATERIALS
IRON AND STEEL
Steel is a compound of iron and carbon intermediate in com-
position between cast and wrought iron, but having a higher spe-
cific gravity than either.
Per cent, of carbon Sp. gr. Properties
Cast iron 5 to 2 7.2 not malleable
nor temperable
Steel 1.5 to .10 7.8 malleable and
temperable
Wrought iron 30 to .05 7.7 malleable, not
temperable
1 The principal methods of manufacture are the crucible process,
the open hearth process, and the Bessemer. In the crucible, im-
pure wrought iron or blister steel with carbon and a flux is fused in
a sealed vessel which air cannot enter: the best tool steels are made
thus. In the open hearth process, pig iron is melted, wrought
iron scrap being added until the proper degree of carbonization
is secured. In the Bessemer process, pig iron is completely decar-
bonized in a converter by an air blast and then recarbonized to the
proper degree by the addition of spiegeleisen. The metal for the
open hearth or for the Bessemer converter is cast into ingots which
are rolled in mills to the required forms. The open hearth pro-
cess produces steel for shafts, axles, armor plate and for structural
purposes, and the Bessemer process mainly produces steel for rail-
road rail. [Mechanical Eng're Handbook, Kent.]
The physical properties of* steel depend upon the method of man-
ufacture and chemical composition, carbon being the controlling
element in regard to strength, and the same is the case with respect
to ultimate elongation. The higher the percentage of carbon
within a reasonable limit the greater the strength and the less the
112 SHIPBUILDING MATERIALS
ultimate elongation. Steel may be given special properties by
adding other elements as nickel, chromium, etc., in which case
the steel is known as alloy or special steel, being given the name of
the element added, as nickel steel, chromium steel, etc.
Carbon Steel. — Here carbon is the controlling element. Carbon
steel may be classified as follows:
Soft, .05-.20% carbon not temperable, easily welded
Medium, .15-40% carbon poor temper, weldable
Hard, ,3O-.70% carbon temperable, welded with difficulty
Very hard, .60-1% carbon high temper, not weldable
Increasing the carbon content of steel increases its strength,
hardness, brittleness, and susceptibility to cracking under sudden
cooling or heating, it also diminishes the elongation and reduction
of area to fracture. Phosphorus increases the tensile strength
about 1,000 lb. per square inch for each .01% but tends to make the
metal brittle.
Average Properties op Steel in Pounds per Square Inch
Medium Hard
Elastic limit in tension and compression 35,000 50,000
Elastic limit shear 30,000 40,000
Tensile strength 60,000 100,000
Compressive strength 60,000 * 120,000
Shearing strength 50,000 75,000
Modulus of rupture 110,000
Modulus of elasticity, tension 30,000,000 30,000,000
Modulus of elasticity, shear . 12,000,000 12,000,000
Ultimate elongation ranges from 5 to 30%, the higher the amount
of carbon the less the elongation. Reduction of area follows the
game rule, ranging from 10 to 60%. Coefficient of expansion
.0000065° F. Sp. gr. about 7.8. Weight per cu. ft. 490-491 lb.
Manganese Steel. — Manganese increases the tensile strength
from 80 to 400 lb. per square inch for each .01% depending on the
carbon present and whether the steel is acid or basic. In its most
serviceable form manganese steel contains about 13 to 14% of
manganese and is practically non-magnetic. On account of its
extreme hardness it is difficult to machine.
The usual analysis of manganese steel lies between the following
limits, manganese 11 to 14%, carbon 1. to 1.3%, silicon .3 to .8%,
phosphorus .05 to .08%, the sulphur content being so as to be
negligible. Manganese steel when tested in the form of a %-in.
Digitized by VJiOOQ 1C
NICKEL STEEL
113
round bar should show a tensile strength of 140,000 lb. per square
inch, elastic limit 90,000, reduction of area not less than 50%,
elongation in 2 ins. not less than 20%. Castings on cooling shrink
to a noticeable extent, and an allowance of about & of an in. should
be made per foot.
Nickel Steel. — Ordinarily contains 1.5 to 4.5% of nickel and
.2 to .5% of carbon. Nickel steel has a larger resistance to wear
and abrasion than carbon steel and greater resistance to corrosion.
When the percentage of nickel is less than 5%, the elastic limit
and tensile strength are increased without any reduction in the
elongation or in the contraction of area. Because of this increase
in strength without loss of ductility nickel steel is used for shafting,
connecting rods, etc., where a steel is required that will combine
great strength and toughness. Tests made at the Watertown
Arsenal (Watertown, Mass.) on a 3.37% nickel steel gave an aver-
age elastic limit of 56,700 lb. per square inch and a tensile strength
of 90,300. It is practically non-corrodible, and has a high electrical
resistance which does not seem to vary much with the percentage
of nickel.
Compakison op Simple Steel and Nickel Steel Forgings
Steel Forging
Nickel Steel Forging
Car-
bon
Tensile
Strength
Elastic
Limit
Elong-
ation,
%
Reduc-
tion of
Area,
%
Car-
bon
Nick-
el
Tensile
Strength
Elastic
Limit
Elong-
ation,
%
Reduc-
tion of
Area,
%
.20
.30
.40
.50
55,000
75,000
85,000
95,000
28,000
37,000
43,000
48,000
34
30
25
21
60
50
45
40
.20
.30
.40
.50
3.5
3.5
3.5
3.5
85,000
95,000
111,000
125,000
48,000
60,000
72,000
85,000
26
22
18
13
55
48
40
32
Nickel steel in the form of shapes, plates, or bars containing
3.25% nickel has a tensile strength of 85,000-100,000 lb. per square
inch, elastic limit 50,000, shearing % of the tensile strength, mod-
ulus of elasticity 29,000,000, elongation 17.G-15%. Sp. gr. of low
carbon nickel steel containing up to 15% nickel is from 7.86 to
7.9 and from 19 to 39% is 7.91 to 8.08.
Silicon Steel. — The addition of silicon to steel appears to in-
crease the strength about 80 lb. per square inch for every .01% up
to a content of 4%; beyond this it impairs the ductility.
Tungsten Steel is characterized by hardness and toughness and
Digitized by VJiOOQlC
114 SHIPBUILDING MATERIALS
its remarkable tempering properties. The tungsten content
ranges from .5% in ordinarybar steel, 2 to 5% in finishing and in-
termediate steels, 4.5 to 12% in self-hardening or air-hardening
steels and 14 to 26% in high speed steels.
Vanadium Steel. — The vanadium content is usually less than
3%. Its effect is to improve the tensile strength, hardness and
toughness.
Chromium Steel. — Here the percentage of chromium varies
from 2.5 to 5%, and of carbon from .8 to .2%. This steel is very
hard and tough. Armor-piercing projectiles are made of it.
Chromium-Nickel Steel. — The influence of both chromium and
nickel is to increase the hardness and strength. Gears, axles,
shafts, and gun barrels are made of it.
Chromium-Vanadium Steel. — Particularly suitable for springs.
Axles and gears are also made of this steel.
Structural Steel. — This is carbon steel rolled into shapes and
plates. Lloyd's rules state: "Steel for shipbuilding shall be made
by the open hearth process, acid or basic. The tensile breaking
strength of steel plates shall be between the limits of 28 and 32
tons per square inch. Plates intended for cold flanging, the tensile
strength shall be between 26 and 30 tons per square inch. The
elongation measured on a standard test piece having a gauge length
of 8 ins., shall not be less than 20% for material .375 inch in thick-
ness and upwards, and not less than 16% for material below .375
inch in thickness. The tensile strength of angles, channels, etc.,
shall be between 28 and 33 tons per square inch. The elongation
on a standard test piece having a gauge length of 8 ins. shall not
be less than 20% for material .375 inch in thickness and upwards,
and not less than 16% for material below. For cold and temper
tests the test pieces shall withstand without fracture, being doubled
over until the internal radius is equal to 1^ times the thickness
of the test piece and the sides are parallel."
American Bureau of Shipping Rules state: "Steel plates, angles
and shapes shall have an ultimate tensile strength of from 58,000
to 68,000 lb. per square inch of 'section, an elastic limit of one-
half the ultimate tensile strength, a reduction of area at point of
fracture of at least 40% and an elongation of 22% in 8 ins. for plates
18 lb. thick and over, and 18% for plates under 18 lb. Material
of greater ultimate tensile strength than 68,000 lb. per square inch
and not above 70,000 lb. may be accepted provided the elongation
and reduction are as specified and the bending tests meet the re-
Digitized by vjOOQ 1C
BEND TESTS 115
quirements. Shapes and angles in excess of 68,000 lb. tensile
strength must be capable of being efficiently welded. Specimens
for all materials (plates and shapes) must stand bending through
180° on a radius of one-half its thickness without fracture on the
convex side either cold or after being heated to cherry red and
quenching in water at 80° F."
Abstracts from the Specifications of Structural Steel for Ships,
issued by the American Society for Testing Materials, are as follows:
"The steel shall be made by the open hearth process and shall con-
form to the following requirements as to chemical composition.
_, , ( Acid not over .06%
Phosphorus:^ . n.ir
( Basic not over .04%
Sulphur not over .05%
"Tension Tests.— Tensile strength 58,000-68,000 lb. per square
inch.
Yield point maximum .5 tensuVstrength.
1 500 000
Elongation in 8 ins. minimum per cent. 7 r. — f -r
tensile strength
"For material over % inch in thickness, a deduction of one from
the percentage of elongation as given above shall be made for
each increase of J^ inch in thickness above % inch to a minimum
of 18%. For material x/i inch or under in thickness the elongation
shall be measured on a gauge length of 24 times the thickness of
the specimen.
"Bend Tests. — The test specimen shall bend cold through 180°
without cracking on the outside of the bent portion as follows:
For material % inch or under in thickness, around a pin the diam-
eter of which is equal to the thickness of the specimen, for material
over % inch to and including \x/i inch in thickness around a pin
the diameter of which is equal to \lA times the thickness of the
specimen, and for material over 1J^ inch in thickness around a
pin the diameter of which is equal to twice the thickness of the
specimen.
"Test Specimens. — Tension and bend test specimens shall be
taken from the finished rolled material. The specimens have a
parallel section not less than 9 ins. long by \XA ins. wide, broad-
ened out at each end to about 2 ins. in width by about 3 ins. long,
making approximately a total length of 18 ins.
"Permissible Variations. — The cross section or weight of each
piece of steel shall not vary more than 2.5% from that specified;
Digitized by vjOOQ IC
116
SHIPBUILDING MATERIALS
except in the case of sheared plates which shall be covered by the
following permissible variations to apply to single plates.
"When ordered to weight for plates 12 J^ lb. per square foot or
over, under 100 ins. in width, 2.5% above or below the specified
Allowable Excess, Expressed as Percentage of
Nominal Weight,
Lb. per Sq. Ft.
Nominal Weight for
Width of Plate as Follows:
Thickness
Ordered, Ins.
50 Ins.
75 Ins.
100 Ins.
1151ns.
Under
to 70
70 Ins.
Under
to 100
to 115
or
50 Ins.
Ins.
Excl.
Over
75 Ins.
Ins.
Excl.
Ins.
Excl.
Over
Hto«/a
5.10 to 6.37
10
15
20
•&*
6.37 to 7.65
8.5
12.5
17
7.65 to 10.20
7
10
15
10.20
10
14
18
A
12.75
8
12
16
7&
15.30
7
10
13
17
■ $
17.85
6
8
10
13
20.40
5
7
9
12
Over y*
22.95
4.5
6.5
8.5
11
25.50
4
6
8
10
3.5
5
6.5
9
Principal Requirements for Steel and Iron for U. S. Naval
Vessels
Minimum Ten-
Elongation
Quality of
Material
sile Strength,
Use
Lb. per Square
Inch
Percent
Ins.
Medium steel, open
Plates and shapes for
60,000
25
8
hearth, carbon.
hull.'
High tensile steel,
Plates and shapes for
80,000
20
8
open hearth, car-
hull.
bon, nickel, or sil-
icon.
Medium steel, open
Rods and bars for riv-
<lHin.dia.,
28
8
hearth, carbon.
ets, bolts, stanchions,
=58,000
davits, etc.
>lHindia.,
60,000
< 1H in. dia.,
30
32
High-tensile steel,
Rods and bars for riv-
23
8
open hearth, car-
ets, bolts, stanchions,
=75,000
bon, nickel, or sil-
davits, etc.
>lHin.dia.,
25
2
icon.
75,000
Steel f orgings, Class
Forgings exposed to
80,000
25
2
A, open hearth,
nickel or carbon.
dynamic actions as
gun mounts.
Steel f orgings, Class
Stems and stern posts,
60,000
30
2
B, open hearth,
rudder stocks, eto.
carbon.
Steel castings, Class
A.
Steel castings, Class
Hawse pipes, turret
tracks, etc.
Stems, stern posts, rud-
80,000
17
2
60,000 to 80,000
22
2
B.
der frames, struts,
etc.
Wrought iron
Miscellaneous forgings.
48.000
*Ir8
by VjUUJ
ac
RIVET STEEL 117
weight; 100 ins. in width or over 5% above or below the specified
weight. For plates under 12J£ lb., under 75 ins. in width 2.5%
above or below the specified weight, 75 to 100 ins. exclusive in
width 5% above or 3% below the specified weight, 100 ins. in
width or over 10% above or 3% below the specified weight.
"When ordered to gauge, the thickness of each plate shall not
vary more than .01 inch under that ordered. An excess over the
nominal weight corresponding to the dimensions on the order shall
be allowed for each plate, if not more than that shown on the table
given on page 116, one cubic inch of rolled steel being assumed to
weigh .2833 lb."
The ultimate strength of steel in tension and compression is
practically the same, and may for different kinds of steel be assumed
as follows:
Kind of Steel
Ultimate Strength,
Pounds per Square Inch
Structural steel for rivets
55,000
60,000
50,000
60,000
75,000
90,000
100,000
125,000
Structural steel for beams
Boiler steel for rivets
Boiler steel for plates
Machine steel
Gun steel
Axle steel
Spring steel
Rivet Steel. — Lloyd's requirements are: "The tensile strength
of steel rivet bars shall be between the limits of 25 and 30 tons per
square inch of section with an elongation of not less than 25% of
the gauge length of eight times the diameter of the test piece."
American Bureau of Shipping: "Materials for rivets shall be
of best open hearth steel, limit of phosphorus and sulphur .04 of
one per cent. Tensile strength to be not less than 45,000 nor
more than 55,000 lb. per square inch."
Abstracts from the Specifications for Rivet Steel for Ships issued
by the American Society for Testing Materials are as follows:
"The steel shall be made by the open hearth process and shall con-
form to the requirements given below:
„, , ( Acid not over .06%
Phosphorus :•{„ . . n,ir
* ( Basic not over .04%
SulPhur • not over .045%,oMe
118 SHIPBUILDING MATERIALS
' ' Tension Tests.— Tensile strength 55,000-65,000 lb. per square inch.
Yield point minimum, .5 tensile strength
1,500,000
Elongation in 8 ins. minimum per cent, tensile strength
"For bars over % inch in diameter, a deduction of one from the
percentage of elongation specified above shall be made for each
increase of y% inch in diameter above % inch.
"Bend Tests. — The test specimen shall bend cold through 180°
flat on itself without cracking on the outside of the bent portion.
"Flattening Tests. — The rivet head shall flatten while hot to
a diameter of 2H times the diameter of the shank without crack-
ing at the edges.
"Permissible Variations. — The gauge of bars 1 in. or under in
diameter shall not vary more than .01 inch from that specified;
the gauge bars over 1 in. to and including 2 ins. in diameter shall
not vary more than A under nor more than ^ inch over that
specified."
See also Rivets and Riveting.
Cast Steel. — A malleable alloy of iron cast from a fluid mass.
It is distinguished from cast iron which is not malleable by being
much lower in carbon and from wrought iron by being free from
intermingled slag. Stern frames, tillers, quadrants, gun mounts,
etc., are made of it.
Lloyd's rules state: "The tensile breaking strength determined
from test pieces of standard dimensions is to be between 28 and
35 tons per sq. in. with an elongation of not less than 20%.
They must also stand being bent cold through an angle of 120°,
the internal radius not being greater than one inch. The castings
are also to be subjected to dropping and hammer tests."
American Bureau of Shipping requirements are: "Tensile
strength not less than 60,000 lb. per sq. in., elongation not less
than 15% in 8 ins. For moving parts a bar one inch square
shall bend cold through an angle of 120° over a radius not exceed-
ing 1J^ ins. and without showing cracks or flaws. For other cast-
ings, tests will be the same except that the angle may be reduced
to 90°. Drop tests shall be made from a height not exceeding
10 ft. on a hard road or floor."
The following abstract is from the Specifications of Steel Cast-
ings issued by the American Society for Testing Materials: "These
specifications cover two classes of castings, viz., Class A ordinary
castings for which no physical requirements are specified, and
Digitized by vjOOQ 1C
IKON
119
Class B for which requirements are specified. There are three
grades in Class B, hard, medium and soft.
"Chemical Composition. —
Class A Class B
Carbon not over .30%
Phosphorus not over .06%
Sulphur
"Physical Properties. —
not over .05%
not over .05%
Hard
Medium
Soft
Tensile strength, lbs. per sq. in
80,000
36,000
15
20
70,000
31,500
18
25
60,000
27,000
Yield, ooint, lbs. per sq. in
Elongation in 2 ins., per cent
22
Reduction of area, per cent
30
"Bend Tests. — The test specimen for soft castings shall bend
cold through 120°, and for medium castings through 90°, around
a 1-inch pin, without cracking on the outside of the bent portion.
Hard castings shall not be subject to bend test requirements.
"Heat Treatment. — Class A castings need not be annealed
unless otherwise specified. Class B shall be annealed, which con-
sists in allowing the castings to become cold, and then uniformly
reheating them to the proper temperature to refine the grain, and
allowing them to cool uniformly and slowly. All castings for ships
shall be annealed.
"Percussion Test. — The casting is suspended by chains and
hammered all over by a hammer of a weight approved by the pur-
chaser. If cracks, flaws or weakness appear after such treatment
the casting will be rejected."
" Shrinkage allowed for casting about A of an inch per foot.
Weight per cubic foot, 490 lb. Sp. gr. 7.8-7.9.
Iron. — Iron plates and shapes for ships have been superseded
by steel as the former are heavier for a given strength. Lloyd's
states: "Deck plating and ordinary floors, also the floors, girders
and top plating of double bottoms in holds, coal bunker and other
bulkheads, shaft tunnels, casings around engines, hatchway
coamings, bulwarks and deck houses may be of iron 10% in excess
of the thicknesses in steel where scantlings for the same are pro-
vided for in the Rules. No other parts of the vessel are to be of
iron without the special sanation of the Committee." Pure iron
has a tensile strength of 40,000 lb. and is very ductile. Weight
per cubic foot 480 lb. Sp. gr. 7.70.
Digitized by LiOOQ LC
120 SHIPBUILDING MATERIALS
Wrought Iron. — Is tough, ductile, malleable, weldable but can-
not be tempered. Boat davits, rail stanchions and a variety of
fittings are made of it. It is composed chiefly of pure iron and
slag (iron silicate) and, in small amounts, the following impurities:
Common wrought iron Best wrought iron.
Carbon .05% .06%
Phosphorus .35 .18
Sulphur .06 .04
Silicon .23 .20
Manganese .... .06
Siag about 3.3 2.80
Tension. — Average of many tests at Columbia University, New
York, on good wrought iron for general purposes:
Elastic limit pounds per square inch 31,000
Ultimate strength 51,000
Elongation in 8 ins. per cent 21
Reduction of area per cent. 30
Modulus of elasticity pounds per square inch. . 28,200,000
Shear and Torsion. — I^st wrought iron which had an ultimate
tensile strength of 48,400 gave as follows:
Ultimate strength in single shear pounds per
square inch 42,000
Elastic limit in torsion 20,530
Ultimate strength 56,400
Modulus of elasticity 12,800,000
Compression. — Ultimate compressive strength of good wrought
iron varies from 55,000 to 60,000 lb. per square inch. Elastic limit
in compression is from 40 to 50% the ultimate strength. • Weight
per cubic foot, 485 lb. Sp. gr. 7.6-7.9.
(From Civil Engineer's Handbook, M. Merriman.)
Cast Iron. — Is brittle, weak in tension and strong in compres-
sion. Its great usefulness comes from the fact that it can be readily
cast in a variety of forms. For engine cylinders hard close grain
iron is called for. Cast iron when exposed to continued heat
becomes permanently expanded lJi to 3% of its length, hence
grate bars should be allowed about 4% play.
Carbon, silicon and other impurities affect the physical properties.
Carbon occurs as combined carbon or as a graphite or uncombined
carbon. When the former the metal is hard, brittle, white, weak in
tension and strong in compression, while in the latter (graphitic
Digitized by VjOOQ 1C
PICKLING AND GALVANIZING 121
carbon) the iron is soft, gray, and weak in tension and compres-
sion. Silicon in cast iron up to .5 % increases its compressive strength,
and the tensile strength is increased up to 2%. Manganese when
below 1 % is not injurious, but when above, it causes hardness and
brittleness. Phosphorus makes the iron weaker and becomes a
serious impurity when it occurs in quantities above 1.5%. Sulphur
causes whiteness, brittleness, hardness and greater shrinkage, and
is in general an objectionable impurity.
Cast iron has an average tensile strength of 22,500 lb. per square
inch, compression about 90,000, modulus of elasticity in tension
varies from 15,000,000 to 20,000,000 lb. per square inch, and in
shear 5,000,000 to 7,000,000. Weight per cubic foot, 449.2. Sp.
gr. 6.85 to 7.4.
Malleable Iron. — This is cast iron that has been heated to a
temperature of about 2,000° F. The castings are packed in retorts
or annealing pots and an oxide of iron (generally hematite ore)
is packed with them. The castings are kept red hot for several
days, causing the carbon near the surface to be burned out, leaving
the outer surface tough and strong like wrought iron while the
interior is hard. Pipe fittings largely are made of it. Tensile
strength 37,000 lb. per square inch.
Pickling and Galvanizing
Pickling. — Steel plates as received from the mill have a scale
which must be removed before they can be painted or cemented,
otherwise when the scale falls off bare places will be left. The
scale is removed by pickling, the plate being stood on end in a
hydrochloric acid bath (19 parts water and 1 of acid), for about
12 hours, then taken out and thoroughly washed with fresh water.
Galvanizing. — Cast iron and wrought- iron fittings exposed to
the weather or to dampness, and sometimes the steel frames and
floors of torpedo boats and destroyers are galvanized. Before
galvanizing all paint must be burned off and the fittings cleaned,
after which they are placed in a bath of one part of hydrochloric
acid and 40 parts of water to remove rust and grease. They are
next dried and placed in a zinc bath from which they are taken
after a sufficient coating of zinc has been deposited on them. The
additional weight due to galvanizing by the hot process is 2J4 to 2lA
ounces and by the electric process about 1 ounce per square foot
of exposed surface. All steel plates less than Y% of an inch thick
should be galvanized before assembling. ^ r^r^Mo
Digitized by vjitJOx L*~
122
SHIPBUILDING MATERIALS
The outward appearance of any galvanized article is not neces-
sarily an indication of its excellence. The only final test of a
zinc coating is the test of time under actual conditions of exposure.
As this takes too long for commercial purposes, various tests have
been devised; among them may be mentioned the lead acetate
by Prof. W. H. Walker (Massachusetts Institute of Technology,
Boston, Mass.). This test is designed to show the weight of actual
coating covering products, and takes into consideration the im-
purities in the coating. The solution employed removes from the
articles both the zinc and zinc iron alloys present. The accurate
weight before and after testing furnishes the basis for computing the
quantitative value of the coating. The weighings must be accurate
to one milligram. The length of time the sample is being tested
is about 3 minutes. For further particulars see "Galvanizing
and Tinning," by W. T. Flanders.
Weights of Steel Plates
in Hundredths of
an Inch
Weight in
Weight in
Thickness, Ins.
Lb. per
Sq. Ft.
Thickness, Ins.
Lb. per
Sq. Ft.
1
55
ioo
.408
loo
22.44
5
100
2.04
60
100
24.48
10
65
loo
4.08
loo
26.52
15
70
Too
6.12
loo
28.56
20
75
100
8.10
loo
30.60
25
100
io.20
80
100
32.64
30
85
loo
12.24
100
34.68
35
100
14.28
90
100
36.72
40
100
16.32
95
100
38.76
45
100
18.36
100
100
40.80
50
loo
20.40
Google
Standard Gauges
Thickness in Decimals of an Inch
Number
of Gauge
Birmingham
Wire Gauge
(B.w.g.)
British
Imperial
United States
Standard
Brown
and Sharpe
Stu
Ste
Wi
t>'s Washburn
el and
re Moen
0000000
.500
.500
000000
....
.464
.46875
00000
.432
.4375
0000
.454
.400
.40625
.46*"
" .3938
000
.425
.372
.375
.40964
. .3625
00
.380
.348
.34375
.3648
. .3310
0
.340
.324
.3125
.32486
. .3065
1
.300
.300
.28125
.2893
'.25
17 .2830
2
.284
.276
.265625
.25763
.21
L9 .2625
3
.259
.252
.25
.22942
.21
12 .2437
4
.238
.232
.234375
.20431
.2(
)7 .2253
5
.220
.212
.21875
.18194
.2(
M .2070
6
.203
.192
.203125
.16202
.2(
)1 .1920
7
.180
.176
.1875
.14428
.11
)9 .1770
8
.165
.160
.171875
.12849
.11
YI .1620
9
.148
.144
.15625
.11443
.11
)4 .1483
10
.134
.128
.140625
.10189
.11
)1 .1350
11
.120
.116
.125
.090742
.1*
*8 .1205
12
.109
.104
.109375
.080808
.1*
S5 .1055
13
.095
.092
.09375
.071961
.1*
12 .0915
14
.083
.080
.078125
.064084
.1*
*0 .0800
15
.072
.072
.0703125
.057068
A\
r8 .0720
16
.065
.064
.0625
.05082
.Vt
!5 .0625
17
.058
.056
.05625
.045257
.Vt
12 .0540
18
.049
.048
.05
.040303
A(
18 .0475
19
.042
.040
.04375
.03589
At
)4 .0410 |
20
.035
.036
.0375
.031961
.1(
U .0348
21
.032
.032
.034375
.028462
.1*
57 .03175
22
.028
.028
.03125
.025347
.1*
55 .0286
' 23
.025
.024
.028125
.022571
M
>3 .0258
24
.022
.022
.025
.0201
At
51 .0230
25
.020
.020
.021875
.0179
A*
t8 .0204
26
.018
.018
.01875
.01594
.1^
L6 .0181
27
.016
.0164
.0171875
.014195
.14
13 .0173
28
.014
.0148
.015625
.012641
Ac
$9 .0162
29
.013
.0136
.0140625
.011257
At
$4 .0150
30
.012
.0124
.0125
.010025
a:
17 .0140
31
.010
.0116
.0109375
.008928
.IS
50 .0132
32
.009
.0108
.01015625
.00795
.11
L5 .0128
33
.008
.0100
.009375
.00708
.11
L2 .0118
34
.007
.0092
.008593
.006304
.11
L0 .0104
35
.005
.0084
.007812
.005614
.1(
)8 .0095
36
.004
.0076
.007031
.005
.1(
)6 .0090
37
.0068
.006640
.004453
.1(
)3
38
.0060
.00625
.003965
.1(
)1
39
....
.003531
.01
)9
40
.003144
.01
)7
123
ioogle
United States Standard Gauge for
and Steel
Sheet and Plate Iron
Approximate Thick-
Approximate Thick-
Weight per Square
Number of Gauge
ness in Fractions
ness in Decimal
Foot in Pounds
of an Inch
Parts of an Inch
Avoirdupois l
0000000
1/2
.5
20.
000000
15/32
.46875
18.75
00000
7/16
.4375
17.5
0000
13/32
.40625
16.25
000
3/8
.375
15.
00
11/32
.34375
13.75
0
5/16
.3125
12.5
1
9/32
.28125
11.25
2
17/64
.265625
10.625
3
1/4
.25
10.
4
15/64
.234375
9.375
5
7/32
.21875
8.75
6
13/64
.203125
8.125
7
3/16
.1875
7.5
8
11/64
.171875
6.875
9
5/32
.15625
6.25
10
9/64
.140625
5.625
11
1/8
.125
5.
12
7/64
.109375
4.375
13
3/32
.09375
3.75
14
5/64
.078125
3.125
15
9/128
.0703125
2.8125
16
1/16
.0625
2.5
17
9/160
.05625
2.25
18
1/20
.05
2.
19
7/160
.04375
1.75
20
3/80
.0375
1.5
21
11/320
.034375
1.375
22
1/32
.03125
1.25
23
9/320
.028125
1.125
24
1/40
.025
1.
25
7/320
.021875
.S75
26
3/160
.01875
.75
27
11/640
.0171875
.6875
28
1/64
.015625
.625
29
9/640
.0140625
.5625
30
1/80
.0125
.5
31
7/640
.0109375
.4375
32
13/1280
.01015625
.40625
33
3/320
.009375
.375
124
Digiti
zed by G00gk
United States Standard Gauge for Sheet and Plate Iron
. and Steel — Continued
Appro ximateThick-
Approximate Thick-
Weight per Square
Number of Gauge
ness in Fractions
ness in Decimal
Foot in Pounds
of an Inch
Parts of an Inch
Avoirdupois1
34
11/1280
.00859375 .
.34375
35
5/640.
.0078125
.3125
36
9/1280
.00703125
.28125
37
17/2560
.006640625
.265625
38
1/160
.00625
.25
On and after July first, eighteen hundred and ninety-three, the above and no
other shall be used in determining duties and taxes levied by the United States of
America on sheet and plate iron and steel. But this act shall not be construed to
increase duties upon any article which may be imported.
In the practical use and application of the standard gauge hereby established a
variation of two and one-half per cent, either way, may be allowed. Approved
March 3, 1893. •
The weight of flat galvanized sheets is based on the weight of black sheets and
two and one-half (2}$) ounces per square foot added for the increase caused by
galvanising.
1 This is based on a cubic foot of wrought iron weighing 480 lb. Steel would be
about 2 per cent heavier.
Diamond Checkered Plates for Engine and Boiler Room
Floors
(Carnegie Steel Co.)
Thickness of
Plate— Rib &*
Above Plate
Width and Length in Inches
Weightper
Square Foot
in Pounds
6*toll%#
12* to 48'
48H" to 00"
%
120
120
120
120
120
120
240
240
240
240
240
180
240
240
240
240
240
240
21.4
A
18.9
y%
16.3
A
13.8
\i
11.2
A
8.7
Classification of Gauges. — Brown & Sharpe (B & S) = Amer-
ican Wire Gauge (AWG); United States Standard Gauge (U S S G) ;
Birmingham Wire Gauge (B W G) ; New British Standard (N B S) =
British Imperial Wire Gauge (I W G) - British Standard Wire
Gauge (S W G).
Digiti
zed by G00gk
125
Weights op Sheets and Plates of Steel, Copper and Brass
(Birmingham Wire Gauge)
Weight per Square Foot
No. of
Thickness
in Inches
Gauge
Steel
Copper
Brass
0000
.454
18.5232
20.5662
19.4312
000
.425
17.3400
19.2525
18.1900
00
.380
15.5040
17.2140
16.2640
0
.340
13.8720
15.4020
14.5520
1
.300
12.2400
13.5900
12.8400
2
.284
11.5872
12.8652
12.1552
3
.259
10.5672
11.7327
11.0852
4
.238
9.7104
10.7814
10.1864
5
.220
8.9760
9.9660
9.4160
6
.203
8.2824
9.1959
8.6884
7
.180
7.3440
8.1540
7.7040
8
.165
6.7320
7.4745
7.0620
9
.148
6.0384
6.7044
6.3344
10
.134
5.4672
6.0702
5.7352
11
.120
4.8960
, 5.4360
5.1360
12
.109
4.4472
4.9377
4.6652
13
.095
3.8760
4.3035
4.0660
14
.083
3.3864
3.7599
3.5524
15
.072
2.9376
3.2616
3.0816
16
,065
2.6520
2.9445
2.7820
17
.058
2.3664
2.6274
2.4824
18
.049
1.9992
2.2197
2.0972
19
.042
1.7136
1.9026
1.7976
20
.035
1.4280
1.5855
1.4980
21
.032
1.3056
1.4496
1.3696
22
.028
1.1424
1.2684
1.1984
23
.025
1.0200
1.1325
1.0700
24
.022
.8976
.9966
.9416
25
.020
.8160
.9060
.8560
26
.018
.7344
.8154
.7704
27
.016
.6528
.7248
.6848
28
.014
.5712
.6342
.5992
29
.013
.5304
.5889
.5564
30
.012
.4896
.5436
.5136
31
.010
.4080
.4530
.4280
32
.009
.3672
.4077
.3852
33
.008
.3264
.3624
.3424
34
.007
.2856
.3171
.2996
35
.005
.2040
.2265
.2140
36
.004
.1632
.1812
.1712
Specific gra
Weight of «
vities
7.85
8.72
8.24
i cubic foot...
489.6
543.6
513.6
Weight of a
cubic inch . .
.2833
^itizsS146
0£[e.2972
126
Weights of Sheets and Plates of Steel, Copper and Brass
(American or Brown and Sharpe Gauge)
Weight per Square Foot
No. of
Thickness
in Inches
Gauge
Steel
Copper
Brass
0000
.460000
18.7680
20.8380
19.6880
000
.409642
16.7134
18.5568
17.5327
00
.364796
14.8837
16.5253
15.6133
0
.324861
13.2543
14.7162
13.9041
1
.289297
11.8033
13.1052
12.3819
2
.257627
10.5112
11.6705
11.0264
3
.229423
9.3605
10.3929
9.8193
4
.204307
8.3357
9.2551
8.7443
5
.181940
7.4232
8.2419
7.7870
6
.162023
6.6105
7.3396
6.9346
7
.144285
5.8868
6.5361
6.1754
8
.128490
5.2424
5.8206
5.4994
9
.114423
4.6685
5.1834
4.8973
10
.101897
4.1574
4.6159
4.3612
11
.090742
3.7023
4.1106
3.8838
12
.080808
3.2970
3.6606
3.4586
13
.071962
2.9360
3.2599
3.0800
14
.064084
2.6146
2.9030
2.7428
15
.057068
2.3284
2.5852
2.4425
16
.050821
2.0735
2.3022
2.1751
17
.045257
1.8465
2.0501
1.9370
18
.040303
1.6444
1 .8257
1.7250
19
.035890
1.4643
1.6258
1.5361
20
.031961
1.3040
1.4478
1.3679
21
.028462
1.1612
1.2893
1 .2182
22
.025346
1.0341
1.1482
1.0848
23
.022572
.92094
1.0225
.99608
24
.020101
.82012
.91058
.86032
25
.017900
.73032
.81087
.76612
26
.015941
.65039
.72213
.68227
27
.014195
.57916
.64303
.60755
28
.012641
.51575
.57264
.54103
29
.011257
.45929
.50994
.48180
30
.010025
.40902
.45413
.42907
31
.008928
.36426
.40444
.38212
32
.007950
.32436
.36014
.34026
33
.007080
.28886
.32072
.30302
34
.006305
.25724
.28562
.26985
35
.005615
.22909
.25436
.24032
36
.005000
.20400
.22650
.21400
37
.004453
.18168
.20172
.19059
38
.003965
.16177
.17961
.16970
39
.003531
.14406
.15995
.15113
40
.003144
.12828
.14242
.13456
127
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128
Digiti
zed by G00gk
Sizes and Weights of Structural Shapes.
A = area of section in square inches
y — distance from center of gravity to extreme fiber in inches
/ = moment of inertia about line through center of gravity
S — section modulus = —
y
r «= radius of gyration
/?
Dimensions in inches, or functions of inches
Weights in pounds per foot.
Shipbuilding Channels
(Carnegie Steel Co.)
L.^J
2
Depth
Weight
Area of
Width
of
Flange,
Inches
Thick-
Dis-
tance
of
Per
Action
ness
Axis 1-1
Axis 2-2
Chan-
nel,
Inches
Foot
in
Pounds
in
Square
Inches
of
Web,
Inches
X
for Axis
/
8
R
/
8
R
2-2
Inches
13
55.0
16.17
4.529
0.904
334.5
51.5
4.55
18.1
5.2
1.06
1.00
50.
14.71
4.416
.791
313.8
48.3
4.62
16.7
4.9
1.07
.98
45.
13.24
4.303
.678
293.1
45.1
4.71
15.3
4.6
1.08
.97
40.
11.76
4.190
.565
272.3
41.9
4.81
13.9
4.3
1.09
.97
37.
10.88
4.122
.497
259.9
40.
4.89
13.1
4.2
1.10
.98
35.
10.29
4.077
.452
251.6
38.7
4.95
12.5
4.1
1.10
.99
32.
9.30
4.000
.375
237.6
36.6
5.06
11.6
3.9
1.12
1.01
12
50.
14.70
4.140
.840
268.6
44 .'8
4.27
17.8
5.8
1.10
1.06
48.4
14.22
4.100
.800
262.8
43.8
4.30
17.3
5.7
1.10
1.05
46.3
13.62
4.050
.750
255.6
42.6
4.33
16.6
5.5
1.11
1.05
44.3
13.02
4.000
.700
248.4
41.4
4.37
16.0
5.4
1.11
1.05
40.
11.76
3.895
.595
233.3
38.9
4.45
14.6
5.1
1.11
1.05
35.
10.30
3.773
.473
215.8
36.
4.58
13.0
4.8
1.12
1.07 ,
40.8
12.00
3.700
.700
217.9
36.3
4.26
11.3
4.
.97
.89
37.2
10.92
3.610
.610
205.0
34.2
4.33
10.4
3.8
.98
.89
32.7
9.60
3.500
.500
189.1
31.5
4.44
9.4
3.6
.99
.89
30.2
8.88
3.440
.440
180.5
30.1
4.51
8.8
3.5
.99
.90
10
40.
11.77
4.091
.741
157.1
31.4
3.65
15.4
5.2
1.14
1.11
36.9
10.86
4.000
.650
149.5
29.9
3.71
14.3
4.9
1.15
1.11
34.4
10.11
3.925
.575
143.2
28.6
3.76
13.4
4.8
1.15
Lll^T^
31.8
9.36
3.860
.500
137.0
27.4
3.83
12.4
4.6
1.15
1.13
129
r
Shipbuilding Channels— Continued
Dis-
Depth
of
Weight
Per
Area of
Action
Width
Thick-
ness
Axis 1-1
Axis 2-2
tance
X
Chan-
Foot
in
in
Square
of
Flange,
Inches
of
Web,
forAxis
nel,
2-2
Inches
Pounds
Inches
Inches
/
S
R
/
S
R
Inches
30.0
8.83
3.797
.447
132.6
26.5
3.88
11.7
4.4
1.15
1.14
32.2
9.75
3.675
.675
124.0
24.8
3.57
9.1
3.3
.97.
.89
30.6
9.00
3.600
.600
117.7
23.5
3.62
8.5
3.1
.97
.88
28.9
8.50
3.550
.550
113.6
22.7
3.66
8.2
3.1
.98
.88
27.2
8.00
3.500
.500
109.4
21.9
3.70
.78
3.
.99
.89
26.4
7.75
3.475
.475
107.3
21.5
3.72
7.6
2.9
.99
.89
28.5
8.38
3.575
.575
108.0
21.6
3.58
7.7
2.8
.96
.84
26.0
7.63
3.500
.500
101.7
20.3
3.65
7.1
2.7
.97
• 84.
24.3
7.13
3.450
.450
97.5
19.5
3.70
6.8
2.6
.97
.85
22.6
6.63
3.400
.400
93.4
18.7
3.75
6.4
2.5
.98
.86
21.7
6.38
3.375
.375
91.3
18.3
3.78
6.2
2.5
.99
.87
9
35.5
10.43
4.025
.675
117.0
26.
3.35
14.1
4.9
1.16
1.16
34.7
10.21
4.000
.650
.550
115.6
25.7
3.36
13.8
4.9
1.16
1.16
31.7
9.31
3.900
109.5
24.3
3.43
12.6
4.6
1.16
1.17
28.6
8.41
3.800
.450
103.4
23.
3.51
11.4
4.4
1.16
1.19
8
27.2
8.00
3.625
.625
68.9
17.2
2.94
8.4
3.2
1.02
.98
26.5
7.80
3.600
.600
67.8
17.
2.95
8.2
3.1
1.03
.98
25.2
7.40
3.550
.550
65.7-
16.4
2.98
7.8
3.
1.03
.98
23.8
7.00
3.500
.500
63.6
15.9
3.01
7.4
3.
1.03
.99
21.5
6.32
3.415
.415
60.0
15.
3.08
6.9
2.9
1.05
.99
21.0
6.16
3.000
.469
54.1
13.5
2.96
4.3
1.9
.83
.79
17.6
5.16
2.875
.344
48.8
12.2
3.07
2.8
1.3
.74
.80
7
24.5
7.20
3.600
.600
48.9
14.
2.61
7.9
3.1
1.05
1.04
23.3
6.85
3.550
.650
47.5
13.6
2.63
7.5
3.
1.05-
1.04
22.1
6.50
3.500
.500
46.0
13.2
2.66
7.1
2.9
1.05
1.05
20.9
6.15
3.450
.450
44.6
12.7
2.69
6.7
2.8
1.05
1.05
19.7
5.80
3.400
.400
43.2
12.3
2.73
6.3
2.7
1.05
1.07
21.9
6.43
3.575
.575
42.6
12.2
2.57
6.5
2.5
1.01
.99
18.6
5.46
3.438
.438
38.7
11.
2.66
5.7
2.3
1.02
.96
16.5
4.85
3.350
.350
36.2
10.3
2.73
5.1
2.2
1.03
.99
15.6
4.59
3.313
.313
36.1
10.
2.77
4.8
2.1
1.03
1.01
6
21.5
6.33
3.685'
• .535
33.3
11.1
2.29
7.8
3.1
1.11
1.16
19.0
5.58
3.560
.410
31.1
10.4
2.36
6.8
2.9
1.10
1.18
15.0
4.46
3.500
.350
25.0
8.3
2.37
5.2
2.1
1.08
1.08
18.1
5.33
3.063
.563
25.4
8.5
2.18
3.5
1.6
.82
.80
13.0
3.83
2*813
.313
20.9
7.
2.34
2.6
1.3
.82
.81
17.0
4.97
2.781
.531
23.5
7.8
2.18
2.8
1.3
.77
.73
12.5
3.66
2.563
.313
19 6
6.5
2.31
2.1
1.1
.75
.74
Wt
17.0
4.99'
3.500
.375
25.8
9.
2.28
5.8
2.5
1.08
1.15
4
13.6
4.00
2.500
.500
8.8
4.4
1.49
2.2
1.4
.74
.87
6.4
1.86
.875
.375
3.2
1.6
1.31
.08
.13
.21
.27
3
7.1
2.05
1.984
.250
2.8
1.9
1.17
.75
.60
.60
.72
Ordering Shapes and Plates. — Structural beams, H beams,
structural channels, shipbuilding channels, bulb angles, bulb beams,
Tees and Zees should be ordered to weight per foot. Angles may
be ordered either to weight per foot or to thickness.
Orders for rounds, squares and other bar mill products should
specify width and thickness in inches and the length in feet and
inches.
, Orders for plates should specify all dimensions in inches.
In the calculation of the areas and weights of the sections on the
following pages, the fillets have been disregarded in accordance with
the rules of the Association of American Steel Manufacturers.
DigitizedbyVj VJVJYIC
Size, Inches
Weight
*£ot
Pounds
56.9
54.0
51.0
48.1
45.0
42.0
38.9
35.8
32.7
29.6
26.4
37.4
35.3
33.1
31.0
28.7
26.5
24.2
21.9
19.6
17.2
14.9
30.6
28.9
27.2
25.4
23.6
21.8
20.0
18.1
16.2
14.3
12.3
19.9
18.5
17.1
15.7
14.3
12.8
11.3
9.8
8.2
6.6
17.1
16.0
14.8
13.6
12.4
Area of
Section,
Sq. Ins.
16.73
15.87
15.00
14.12
13.23
12.34
11.44
10.53
9.61
8.68
7.75
11.00
10.37
9.73
9.09
8.44
7.78
7.11
6.43
5.75
5.06
4.36
9.00
8.50
7.98
7.47
6.94
6.40
5.86
5.31
4.75
4.18
3.61
5.84
5.44
5.03
4.61
4.18
3.75
3.31
2.86
2.40
1.94
5.03
4.69
4.34
3.98
3.62
Axis 1-1 and Axis 2-2
98.0
93.5
89.0
84.3
79.6
74.7
69.7
64.6
59.4
54.1
48.6
35.5
33.7
31.9
30.1
28.2
26.2
24.2
22.1
19.9
17.7
15.4
19.6
18.7
17.8
16.8
15.7
14.7
13.6
12.4
11.3
10.0
8.7
8.1
7.7
7.2
6.7
6.1
5.6
5.0
4.4
3.7
3.0
5.3
5.0
4.7
4.3
4.0
2.42
2.43
2.44
2.44
2.45
2.46
2.47
2.48
2.49
2.50
2.51
1.80
1.80
1.81
1.82
1.83
1.83
1.84
1.85
1.86
1.87
1.88
1.48
1.48
1.49
1.50
1.50
1.51
1.52
1.53
1.54
1.55
1.56
1.18
1.19
1.19
1.20
1.21
1.22
1.23
1.23
1.24
1.25
1.02
1.03
1.04
1.04
1.05
17.5
16.7
15.8
14.9
14.0
13.1
12.2
11.2
10.3
9.3
8.4
8.6
8.1
7.6
7.2
6.7
6.2
5.7
5.1
4.6
4.1
3.5
5.8
5.5
5.2
4.9
4.5
4.2
3.9
3.5
3.2
2.8
2.4
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.5
1.3
1.0
2.3
2.1
2.0
1.8
1.6
2.41
2.39
2.37
2.34
2.32
2.30
2.28
2.25
2.23
2.21
2.19
1.86
1.84
1.82
1.80
1.78
1.75
1.73
1.71
1.68
1.66
1.64
1.61
1.59
1.57
1.55
1.52
1.50
1.48
1.46
1.43
1.41
1.39
1.29
1.27
1.25
1.23
1.21
1.18
1.16
1.14
1.12
1.09
1.17
1.15
1.12
1.10
1.08
131
y Google
Equal Angles — Continued
Weight
Area of
Axis 1-1 and Axis 2-2
Site, Inches
Foot
Section
Sq. Ins.
Pounds
A
I
R
S
X
3HX8HX H
11.1
3.25
3.6
1.06
1.5
1.06
ft::::::
9.8
2.87
3.3
1.07
1.3
1.04
8.5
2.48
2.9
1.07
1.2
1.01
ft::::::
7.2
2.09
2.5
1.08
.98
.99
5.8
1.69
2.0
1.09
.79
.97
3* X 34 X ^ .
11.5
10.4
9.4
8.3
7.2
6.1
4.9
7.7
3.36
3.06
2.75
2.43
2.11
1.78
1.44
2.25
2.6
2.4
2.2
2.0
1.8
1.5
1.2
1.2
.88
.89
.90
.91
.91
.92
.93
.74
1.3
1.2
1.1
.95
.83
.71
.58
.73
.98
.95
15
.93
■rir
.91
£|
.89
A
.87
H.;..:
.84
2H X 2M X H
.81
ft::::::"
6.8
2.00
1.1
.75
.65
.78
5.9
1.73
.98
.75
.57
.76
£::;:::
5.0
1.47
.85
.76
.48
.74
4.1
1.19
.70
.77
.39
.72
A::::::
3.07
.90
.55
.78
.30
.69
2.08
.61
.38
.79
.20
.67
2 X 2 X A-
5.3
4.7
3.92
3.19
2.44
1.66
4.6
1.56
1.36
1.15
.94
.71
.48
1.34
.54
.48
.42
.35
.28
.19
.35
.59
.59
.60
.61
.62
.63
.51
.40
.35
.30
.25
.19
.13
.30
.66
A A g
.64
A . ".
.61
g
.59
*.....
.57
#:::::
.55
IX X IH X A
.59
3.99
1.17
.31
.51
.26
.57
ft::::::
3.39
1.00
.27
.52
.23
.55
2.77
.81
.23
.53
.19
.53
ft::::::
2.12
.62
.18
.54
.14
.51
1.44
.42
.13
.55
.10
.48
W X W X H
3.35
.98
.19
.44
.19
.51
ft::::::
2.86
.84
.16
.44
.16
.49
2.34
.69
.14
.45
.13
.47
ft::::::
1.80
.53
.11
.46
.10
.44
1.23
.36
.08
.46
.07
.42
1HXIH X p
2.33
.68
.09
.36
.11
.42
1.92
.56
.08
.37
.09
.40
&:::::
1.48
.43
.06
.38
.07
.38
1.01
.30
.04
.38
.05
.35
1 X 1 XW
1.49
.44
.04
.29
.06
.34
A
1.16
.80
.34
.23
.03
.02
.30
.31
.04
.03
.32
5::::::.:..
.30
Stove Bolts.*— Have either button or flush head similar to ordi-
nary wood screws, but have threads for nut at end.
Dia. of bolt, in. V% A A A lA A %
Threads per in. 32 28 24 22 18 18 16
Carriage Bolts. — Have button heads, and below is a square shank
at end of which are threads for a nut.
Diameter of bolt, in. KA^A^A^Ji^ 1
Thickness of head, in. H AAAMAA^A^
Diameter of head, in. % % U % 1 W% IH Wt 1% 2
The length of thread depends on the length of the bolt, the thread
being about three times the thickness of the nut. See Table of Bolts
and Nuts.
132
Digiti
zed by G00gle
Unequal Angles
Weight
Area of
Axis 1-1
Alia 2-2
Sue, Inches
Foot
Section
Sq.Ins.
Pounds
A
/
8
B
■
1
5
ft
V
8X6X1 ...
44.2
13.00
80.8
15.1
2.49
2.65
38.8
8.9
1.73
1.65
H....
41.7
12.25
76.6
14.3
2.50
2.63
36.8
8.4
1.73
1.63
y& . . . .
39.1
11.48
72.3
13.4
2.51
2.61
34.9
7.9
1.74
1.61
+| •• • •
36.5
10.72
67.9
12.5
2.52
2.59
32.8
74
1.75
1.59
££.. . .
33.8
9.94
63.4
11.7
2.53
2.56
30.7
69
1.76
1.56
if...
31.2
9.15
58.8
10.8
2.54
2.54
28.6
6.4
1.77
1.54
». .
28.5
8.36
54.1
9.9
2.54
2.52
26.3
5.9
1.77
1.52
A...
25.7
7.56
49.3
8.9
2.55
2.50
24.0
5.3
1.78
1.50
i .
23.0
6.75
44.3
8.0
2.56
2.47
21.7
4.8
1.79
1.47
v ::::
20.2
5.93
39.2
7.1
2.57
2.45
19.3
4.2
1.80
1.45
8X3MX1 ..
35.7
10.50
66.2
13.7
2.51
3.17
7.8
3.0
.86
.92
g::
33.7
9.90
62.9
12.9
2.52
3.14
7.4
2.9
.87
.89
31.7
9.30
59.4
12.2
2.53
3.12
7.1
2.7
.87
.87
»-.
29.6
8.68
55.9
11.4
2.54
3.10
6.7
2.5
.88
.85
k-
27.5
8.06
52.3
10.6
2.55
3.07
6.3
2.3
.88
.82
H-.
25.3
7.43
48.5
9.8
2.56
3.05
5.9
2.2
.89
.80
*..
23.2
6.80
44.7
9.0
2.57
3.03
5.4
2.0
.90
.78
A-
21.0
6.15
40.8
8.2
2.57
3.00
5.0
1.8
.90
.75
H-
18.7
5.50
36.7
7.3
2.58
2.98
4.5
1.6
.91
.73
A-
16.5
4.84
32.5
6.4
2.59
2.95
4.1
1.5
.92
.70
7X3HX1 ..
32.3
9.50
45.4
10.6
2.19
2.71
7.5
3.0
.89
.96
S::
30.5
8.97
43.1
10.0
2.19
2.69
7.2
2.8
.89
.94
28.7
8.42
40.8
9.4
2.20
2.66
6.8
2.6
.90
.91
«..
26.8
7.87
38.4
8.8
2.21
2.64
6.5
2.5
.91
.89
«..
24.9
7.31
36.0
8.2
2.22
2.62
6.1
2.3
.91
.87
«..
23.0
6.75
33.5
7.6
2.23
2.60
5.7
2.1
.92
.85
N-
21.0
6.17
30.9
7.0
2.24
2.57
5.3
2.0
.93
.82
A.
19.1
5.59
28.2
6.3
2.25
2.55
4.9
1.8
.93
.80
«..
17.0
5.00
25.4
5.7
2.25
2.53
4.4
1.6
.94
.78
ft::
15.0
4.40
22.6
5.0
2.26
2.50
4.0
1.4
.95
.75
13.0
3.80
19.6
4.3
2.27
2.48
3.5
1.3
.96
.73
6X4X1 ....
30.6
9.00-
30.8
8.0
1.85
2.17
10.8
3.8
1.09
1.17
8--:
28.9
8.50
29.3
7.6
1.86
2.14
10.3
3.6
1.10
1.14
27.2
7.98
27.7
7.2
1.86
2.12
9.8
3.4
1.11
1.12
«....
25.4
7.47
26.1
6.7
1.87
2.10
9.2
3.2
1.11
1.10
8....
23.6
6.94
24.5
6.2
1.88
2.08
8.7
3.0
1.12
1.08
«....
21.8
6.40
22.8
5.8
1.89
2.06
8.1
2.8
1.13
1.06
«....
20.0
5.86
21.1
5.3
1.90
2.03
7.5
2.5
1.13
1.03
A-..
18.1
5.31
19.3
4.8
1.90
2.01
6.9
2.3
1.14
1.01
H- ...
16.2
4.75
17.4
4.3
1.91
1.99
6.3
2.1
1.15
.99
A....
14.3
4.18
15.5
3.8
1.92
1.96
5.6
1.8
1.16
.96
N-...
12.3
3.61
13.5
3.3
1.93
1.94
4.9
1.6
1.17
.94
6X3HX1 ..
28.9
8.50
29.2
7.8
1.85
2.26
7.2
2.9
.92
1.01
1:
27.3
8.03
27.8
7.4
1.86
2.24
6.9
2.7
.93
.99
25.7
7.55
26.4
7.0
1.87
2.22
6.6
2.6
.93
.07
24.0
7.06
24.9
6.6
1.88
2.20
6.2
2.4
.94
.95
133
Unequal Angles — Continued
Weight
Area of
Axial-l
Axis 2-2
Size, Inches
per
Foot
Section
Sq. Ins.,
Pounds
A
/
S
R
X
/
8
R
y
6 X3M X %..
22 4
6.56
23.3
6.1
1.89
2.18
5.8
2.3
.94
.93
«••
20.6
6.06
21.7
5.6
1.89
2.15
5.5
2.1
.95
.90
• %..
18.9
.5.55
20.1
5.2
1.90
2.13
5.1
1.9
.96
.88
ft..
17.1
5.03
18.4
4.7
1.91
2.11
4.7
1.8
.96
.86
**..
15.3
4.50
16.6
4.2
1.92
2.08
4.3
1.6
.97
.83
fc:
13.5
3.97
14.8
3.7
1.93
2.06
3.8
1.4
.98
.81
11.7
3.42
12.9
3.3
1.94
2.04
3.3
1.2
.99
.79
ft.-
9.8
2.87
10.9
2.7
1.95
2.01
2.9
1.0
1.00
.76
5X4X %....
24.2
7.11
16.4
5.0
1.52
1.71
9.2
3.3
1.14
1.21
if....
22 7
6.65
15.5
4.7
1.53
1.68
8.7
3.1
1.15
1.18
&....
2l!l
6.19
14.6
4.4
1.54
1.66
8.2
2.9
1.15
1.16
8::::
19.5
5.72
13.6
4.1
1.54
1.64
7.7
2.7
1.16
1.14
17.8
5.23
12.6
3.7
1.55
1.62
7.1
2.5
1.17
1.12
ft....
16.2
4.75
11.6
3.4
1.56
1.60
6.6
2.3
1.18
1.10
M-...
14.5
4.25
10.5
3.1
1.57
1.57
6.0
2.0
1.18
1.07
ft::::
5X3HXK-..
12.8
3.75
9.3
2.7
1.58
1.55
5.3
1.8
1.19
1.05
11.0
3.23
8.1
2.3
1.59
1.53
4.7
1.6
1.20
1.03
22.7
6.67
15.7
4.9
1.53
1.79
6.2
2.5
.96
1.04
tt...
21.3
6.25
14.8
4.6
1.54
1.77
5.9
2.4
.97
1.02
X...
19.8
5.81
13.9
4.3
1.55
1.75
5.6
2.2
.98
1.00
8:::
18.3
5.37
13.0
4.0
1.56
1.72
5.2
2.1
.98
.97
16.8
4.92
12.0
3.7
1.56
1.70
4.8
1.9
.99
.95
S:::
15.2
4.47
11.0
3.3
1.57
1.68
4.4
1.7
1.00
.93
13.6
4.00
10.0
3.0
1.58
1.66
4.0
1.6
1.01
.91
ft...
12.0
3.53
8.9
2.6
1.59
1.63
3.6
1.4
1.01
.88
M--
10.4
3.05
7.8
2.3
1.60
1.61
3.2.
1.2
1.02
.86
ft...
8.7
2.56
6.6
1.9
1.61
1.59
2.7
1.0
1.03
.84
5X3Xfl
19.9
5.84
14.0
, 4.5
1.55
1.86
3.7
1.7
.80
.86
H
18.5
5.44
13.2
4.2
1.55
1.84
3.5
1.6
.80
.84
it
17.1
5.03
12.3
3.9
1.56
1.82
3.3
1.5
.81
.82
^
15.7
4.61
11.4
3.5
1.57
1.80
3.1
1.4
.81
.80
ft
14.3
4.18
10.4
3.2
1.58
1.77
2.8
1.3
.82
.77
M
12.8
3.75
9.5
2.9
1.59
1.75
2.6
1.1
.83
.75
ft
11.3
3.31
8.4
2.6
1.60
1.73
2.3
1.0
.84
73
Vs
9.8
2.86
7.4
2.2
1.61
1.70
2.0
.89
.84
.70
ft
8.2
2.40
6.3
1.9
1.61
1.68
1.8
.75
.85
.68
4MX3XH-..
18.5
5.43
10.3
3.6
1.38
1.65
3.6
1.7
.81
.90
%...
17.3
5.06
9.7
3.4
1.39
1.63
3.4
1.6
.82
.88
\\...
16.0
4.68
9.1
3.1
1.39
1.60
3.2
1.5
.83
.85
%-■
14.7
4.30
8.4
2.9
1.40
1.58
3.0
1.4
.83
.83
ft--
13.3
3.90
7.8
2.6
1.41
1.56
2.8
1.3
.85
.81
H--
11.9
3.50
7.0
2.4
1.42
1.54
2.5
1.1
.85
.79
ft--
10.6
3.09
6.3
2.1
1.43
1.51
2.3
1.0
.85
.76
H-.
9.1
2.67
5.5
1.8
1.44
1.49
2.0
.88
.86
.74
4X3HXil'^
7.7
2.25
4.7
1.5
1.44
1.47
1.7
.75
.87
.72
18.5
5.43
7.8
2.9
1.19
1.36
5.5
2.3
1.01
1.11
&...
17.3
5.06
7.3
2.8
1.20
1.34
5.2
2.1
1.01
1.09
tt...
16.0
4.68
6.9
2.6
1.21
1.32
4.9
2.0
1.02
1.07
H-.
14.7
4.30
6.4
2.4
1.22
1.29
4.5
1.8
1.03
1.04
ft...
13.3
3.90
5.9
2.1
1.23
1.27
4.2
1.7
1.03
1.02
H-..
11.9
3.50
5.3
1.9
1.23
1.25
3.8
1.5
1.04
1.00
fe::
10.6
3.09
4.8
1.7
1.24
1.23
3.4
1.3
1.05
.98
9.1
2.67
4.2
1.5
1.25
1.21
3.0
1.2
1.06
.96
ft...
7.7
2.25
3.6
1.3
1.26
1.18
2.6
1.0
1.07
.93
4X3XH
17.1
5.03
7.3
2.9
1.21
1.44
3.5
1.7
.83
.94
M
16.0
4.69
6.9
2.7
1.22
1.42
3.3
1.6
.84
.92
H
14.8
4.34
6.5
2.5
1.22
1.39
3.1
1.5
.84
.89
%
13.6
3.98
6.0
2.3
1.23
1.37
2.9
1.4
.85
.87
ft
12.4
3.62
5.6
2.1
1.24
1.35
2.7
1.2
.86
.85
M
11.1
3. 55
5.0
1.9
1.25
1.33
2.4
1.1
.86
.83
ft
9.8
2.87
4.5
1.7
1.2-i
1.30
2.2
1.0
.87
.80
134
y Google
Unequal Angles — Continued
Weight
Area of
Axis 1-1
Axis 2-2
Foot
Section
Sq. Ins..
Siae, IncheB
Pounds
A
/
S
R
X
/
8
R
V
4 X3 XH
8.5
2.48
4.0
1.5:
1.26
1.28
1.9
.87
.88
.78
ft:::::
7.2
2.09
3.4
1.2-
1.27
1.26
1.7
.74
.89
.76
5.8
1.69
2.8
1.0
1.28
1.24
1.4
.60
.89
.74
3JiX3XH-
15.8
4.62
5.0
2.2.
1.04
1.23
3.3
1.7
.85
.98
14.7
4.31
4.7
2.1.
1.04
1.21
3.1
1.5
.85
.96
■H*'
13.6
4.00
4.4
1.9
1.05
1.19
3.0
1.4
.86
.94
H—
12.5
3.67
4.1
1.8
1.06
1.17
2.8
1.3
.87
.92
1:::
11.4
3.34
3.8
1.6
1.07
1.15
2.5
1.2
.87
.90
10.2
3.00
3.5
1.5
1.07
1.13
2.3
1.1
.88
.88
ft:::
9.1
2.65
3.1
1.3
1.08
1.10
2.1
.98
.89
.85
7.9
2.30
2.7
1.1
1.09
1.08
1.8
.85
.90
.83
ft:::
%6.6
1.93
2.3
.90
1.16
1.06
1.6
.72
.90
.81
5.4
1.56
1.9
.78
1.11
1.04
1.3
.58
.91
.79
3K X 2H X «•
78-
12.5
11.5
3.65
3.36
4.1
3.8
1.9
1.7
1.06
1.07
1.27
1.25
1.7
l.G
.99
.92
.69
.69
.77
.75
ft:
10.4
3.06
3.6
1.6
1.08
1.23
1.5
.84
.70
.73
9.4
2.75
3.2
1.4
1.09
1.20
1.4
.76
.70
.70
8:
8.3
2.43
2.9
1.3
1.09
1.18
1.2
.68
.71
.68
7.2
2.11
2.6
1.1
1.10
1.16
1.1
.59
.72
.66
ft:
6.1
1.78
2.2
.93
1.11
1.14
.94
.50
.73
.64
4.9
1.44
1.8
.75
1.12
1.11
.78
.41
.74
.61
3 X 2H Xft.--
9.5
2.78
2.3
1.2
.91
1.02
1.4
.82
.72
.77
8.5
2.50
2.1
1.0
.91
1.00
1.3
.74
.72
.75
A--
7.6
2.21
1.9
.93
.92
.98
1.2
.66
.73
.73
8...
6.6
1.92
1.7
.81
.93
.96
1.0
.58
.74
.71
ft:::
5.6
1.62
1.4
.69
.94
.93
.90
.49
.74
.68
4.5
1.31
1.2
.56
.95
.91
.74
.40
.75
.66
3 X 2 X H
7.7
2.25
1.9
1.0
.92
1.08
.67
.47
.55
.58
'6.8
2.20
1.7
.89
.93
1.06
.61
.42
.55
.56
Si
5.9
1.73
1.5
.78
.94
1.04
.54
.37
.56
.54
5.0
1.47
1.3
.66
.95
1.02
.47
.32
.57
.52
4.1
1.19
1.1
.54
.95
.99
.39
.25
.57
.49
2J4X2XH...
ft:::
6.8
2.00
1.1
.70
.75
.88
.64
.46
.56
.63
6.1
1.78
1.0
.62
.76
.85
.58
.41
.57
.60
5.3
1.55
.91
.55
.77
.83
.51
.36
.58
.58
I:
2HX1HXA-
4.5
1.31
.79
.47
.78
.81
.45
.31
.58
.56
3.62
1.06
.65
.38
.78
.79
.37
.25
.59
.54
2.75
.81
.51
.29
.79
.76
.29
.20
.60
.51
1.86
.55
.35
.20
.80
.74
.20
.13
.61
.49
3.92
3.19
1.15
.94
.71
.59
.44
.36
.79
.79
.90
.88
.19
.16
.17
.14
.41
.41
.40
.38
A-
2.44
.78
.46
.28
.80
.85
.13
.11
.42
.35
2M X im X H.
5.6
5.0
1.03
1.45
.75
.68
.54
.48
.68
.69
.86
.83
.26
.24
.26
.23
.40
.41
.48
.46
4.4
1.27
.61
.42
.69
.81
.21
.20
.41
.44
I
JXWXH...
1:
2XMXH'-
IK X IK X K.
3.66
1.07
.53
.36
.70
.79
.19
.17
.42
.42
2.98
.88
.44
.30
.71
.77
.16
.14
.42
.39
2.28
.67
.34
.23
.72
.75
.12
.11
.43
.37
3.99
3.39
1.17
1.00
.43
.38
.34
.29
.61
.62
.71
.69
.21
.18
.20
.17
.42
.42
.46
.44
2.77
.81
.32
.24
.62
.66
.15
.14
.43
.41
2.12
.62
.25
.18
.63
.64
.12
.11
.44
.39
1.44
.42
.17
.13
.64
.62
.09
.08
.45
.37
2.55
1.96
.75
.57
.30
.23
.23
.18
.63
.64
.71
.69
.09
.07
.10
.08
.34
.35
.33
.31
2.34
1.80
.69
.53
.20
.16
.18
.14
' .54
.55
.60
.58--
.09
.07
.10
.08
.35
.36
.35
.33
1.23
.36
.11
.09
.56
.56
.05
.05
.37
.31
W2XVAX A.
A^
2.59
2.13
.76
.63
.16
.13
.16
.13
.45
.46
.52
.50
.10
.08
.11
.09
.35
.36
.40
.38
1.64
.48
.10
.10
.46
.48
.07
.07
r*7
.35
135
uiflitizsa by V-jvJ<J^L'C
I Beams
Depth
Of
Beam
Weight
Ana
of
Section
Width
of
J Vuv
Thiek-
Aria 1-1
A™ 2-2
per
loot
of
Web
/
S
R
/
S
fi
27
83.
24.41
7.5
.424
2888.6
214.
10.88
53.1
14.1
1.47
115.0
33.98
8.
.750
2955.5
246.3
9.33
83.2
20.8
1.57
24
110.0
32.48
7.938
.688
2883.5
240.3
9.42
81.
20.4
1.58
105.
30.98
7.875
.625
2811.5
234.3
9.53
78.9
20.
1.60
100.
29.41
7.254
.754
2379.6
198.3
9.00
48.6
13.4
1.28
95.
27.94
7.193
.693
2309.
192.4
9.09
47.1
13.1
1.30
90.
26.47
7.131
.631
2238.4
186.5
9.20
45.7
12.8
1.31
85.
25.00
7.070
.570
2167.8
180.7
9.31
44.4
12.6
1.33
80.
23.32
7.
.5
2087.2
173.9
9.46
42.9
12.3
1.36
69.5
20.44
7.
.39
1928.
160.7
9.71
39.3
11.2
1.39
21
57.5
16.85
6.5
.357
1227.5
116.9
9.54
28.4
8.8
1.30
20
100.
29.41
7.284
.884
1655.6
165.6
7.50
52.7
14.5
1.34
95.
27.94
7.210
.810
1606.6
160.7
7.58
50.*
14.1
1.35
90.
26.47
7.137
.737
1557.6
155.8
7.67
49.
13.7
1.36
85.
25.00
7.063
.663
1508.5
150.9
7.77
47.3
13.4
1.37
80.
23.53
7.
.6
1466.3
146.6
7.86
45.8
13.1
1.39
75.
22.05
6.399
.649
1268.8
126.9
7.58
30.3
9.5
1.17
70.
20.59
6.325
.575
1219.8
122.
7.70
29.
9.2
1.19
65.
19.12
6.25
.5
1169.5
117.
7.83
27.9
8.9
1.21
18
90.
17.65
7.245
.807
1260.4
140.
6.90
52.
14.4
1.40
85.
15.93
7.163
.725
1220.7
135.6
6.99
50.
14.0
1.42
80.
13.53
7.082
.644
1181.
131.2
7.09
48.1
13.6
1.43
75.
22.06
7.
.562
1141.3
126.8
7.19
46.2
13.2
1.45
70.
20.59
6.259
.719
921.2
102.4
6.69
24.6
7.9
1.09
65.
19.12
6.177
.637
881.5
97.9
6.79
23.5
7.6
1.11
60.
17.67
6.095
.555
841.8
93.5
6.91
22.4
7.3
1.13
55.
15.93
6.
.46
795.6
88.4
7.07
21.2
7.1
1.15
46.
13.53
6.
.322
733.2
81.5
7.36
19.9
6.6
1.21
15
75.
22.06
6.292
.882
691.2
92.2
5.60
30.7
9.8
1.18
70.
20.59
6.194
.784
663.7
88.5
5.68
29.
9.4
1.19
65.
19.12
6.096
.686
636.1
84.8
5.77
27.4
9.
1.20
60.
17.67
6.
.59
609.
81.2
5.87
26.
8.7
1.21
55.
16.18
5.746
.656
511.
68.1
5.62
17.1
5.9
1.02
50.
14 71
5.648
.558
483.4
64.5
5.73
16.
5.7
1.04
45.
13.24
5.550
.46
455.9
60.8
5.87
15.1
5.4
1.07
42.
12.48
5.5
.41
441.8
58.9
5.95
14.6
5.3
1.08
36.
10.63
5.5
.289
405.1
54.
6.17
13.5
4.9
1.13
12
55.
16.18
5.611
.821
321.
53 5
4.45
17.5
6.2
1.04
50.
14.71
5.489
.699
303.4
50.6
5.54
16.1
5.9
1.05
136
y Google
I Beams — Continued
Depth
Weight
Area
Width
Thick-
Axifll—1
Axis 2— 2
of
Beam
Foot
of
Section
of
Flange
ness
of
Web
/
i
S
R
/
8
B
12
45.
13.24
5.366
.576
285.7
47.6
4.65
14.9
5.6
1.06
40.
11.84
5.25
.460
269.
44.8
4.77
13.8
5.3
1.08
35.
10.29
5.086
.436
228.3
38.
4.71
10.1
4.
1.09
31.5
9.26
5.
.35
215.8
36.
4.83
9.5
3.8
1.01
27.5
8.04
5.
.255
199.6
33.3
4.98
8.7
3.5
1.04
10
40.
11.76
5.099
.749
158.7
31.7
3.67
9.5
3.7
.90
35.
10.29
4.952
.602
146.4
29.3
3.77
8.5
3.4
.91
30.
8.82
4.805
.455
134.2
26.8
3.90
7.7
3.2
.93
25.
7.37
4.66
.310
122.1
24.4
4.07
6.9
3.
.97
22.
6.52
4.67
.232
113.9
22.8
4.18
6.4
2.7
.99
9
35.
10.29
4.772
.732
111.8
24.8
3.29
7.3
3.1
.84
30.
8.82
4.609
.569
101.9
22.6
3.40
6 4
2.8
.85
25.
7.35
4.446
.406
91.9
20.4
3.54
5.7
2.5
.88
21.
6.31
4.33
.29
84.9
18.9
3.67
5.2
2.4
.90
8
25.5
7.50
4.271
.541
68.4
17.1
3.02
4.8
2.2
.80
23.
6.76
4.179
.449
64.5
16.1
3.09
4.4
2.1
.81
20.5
6.03
4.087
.357
60.6
15.2
3.17
4.1
2.
.82
18.
6.33
4.
.27
56.9
14.2
3.27
3.8
1.9
.84
17.5
5.15
4.33
.21
58.3
14.6
3.37
4.5
2.1
.93
7
20.
5.88
3.868
.458
42.2
12.1
2.68
3.2
1.7
.74
17.5
5.15
3.763
.353
39.2
11.2
2.76
2.9
1.6
.76
15.
4.42
3.66
.25
36.2
10.4
2.86
2.7
1.6
.78
6
17.25
5.07
3.575
.475
26.2
8.7
2.27
2.4
1.3
.68
14.75
4.34
3.452
.352
24.
8.
2.35
2.1
1.2
.69
12.25
3.61
3.33
.23
21.8
7.3
2.46
1.9
1.1
.72
5
14.75
4.34
3.294
.504
15.2
6.1
1.87
1.7
1.
.63
12.25
3.6
3.147
.357
13.6
5.5
1.94
1.5
.92
.63
9.75
2.87
3.
.21
12.1
4.8
2.05
1.2
.82
.65
4
10.5
3.09
2.88
.41
7.1
3.6
1.52
1.
.7
.57
9.5
2.79
2.807
.337
6.8
3.4
1.55
.93
.66
.58
8.5
2.5
2.733
.263
6.4
3.2
1.59
.85
.62
.58
7.6
2.21
2.66
.190
6.
3.
1.64
.77
.68
.59
3
7.5
2.21
2.521
.361
2.9
1.9
1.15
.60
.48
.52
6.5
1.91
2.423
.263
2.7
1.8
1.19
.53
.44
.52
5.5
1.63
2.33
.170
2.5
1.7
1.23
.46
.40
.53
Half Rounds
Diameter A" to J£*\ inclusive, advancing by 64ths.
ft" " 1%', a * 16ths.
2", 2W, 3",
Rounds
Diameter -
tA' to \%/i'y inclusive, advancing by 64ths.
Iff' u W, * tt * 32nds.
a 3A' a 7", «" u 16ths.
See also page 143
137
Digiti
zed by G00gk
Bulb Beams
12
f
j%
Depth
Weight
Area
Width
Thick-
Axis
1—1
Axis 2— 2
•
of
Beam
per
Foot
of
Section
of
Flange
of
Web
/
A
R
X
/
S
R
V
10
36.6
10.62
5.500
.625
140.4
25.3
3.64
4.45
7.6
2.8
.84
2.75
28.1
8.12
5.250
.375
118.6
20.7
3.82
4.28
6.3
2.4
.88
2.63
9
30.1
8.83
5.125
.563
95.8
19.4
3.29
4.06
5.4
2.1
.78
2.56
24.3
7.15
4.938
.375
84.0
16.6
3.43
3.95
4.6
1.9
.80
2.47
8
24.2
7.11
5.156
.469
62.8
14.1
2.97
3.54
4.5
1.7
.79
2.58
20.0
5.86
5.000
.313
55.6
12.2
3.08
3.43
3.9
1.6
.82
2.50
7
23.3
6.85
5.094
.531
45.5
11.7
2.57
3.11
4.3
1.7
.79
2.55
18.1
5.32
4.875
.313
38.8
9.7
2.70
2.98
3.6
1.5
.82
2.44
6
17.2
5.00
4.524
.430
24.4
7.2
2.20
2.61
2.7
1.2
.73
2.26
14.0
4.11
4.375
.281
21.6
6.1
2.28
2.46
2.2
1.0
.72
2.19
H Beams
Depth
of
Weight
Area
of
Width
of
Thick-
ness
Axis 1 — 1
Axis 2— 2
per
of
Web
Beam
Foot
Section
Flange
/
S
R
/
S
R
8
34.
10.
8.
.375
115.4
28.9
3.40
35.1
8.8
1.87
6
23.8
7.
6.
.313
45.1
15.
2 54
14.7
4.9
1.45
5
18.7
5.50
5.
.313
23.8
9.5
2.08
7.9
3.1
1.20
4
13.6
4.
4.
.313
10.7
5.3
1.63
3.6
1.8
.95
138
y Google
Bulb Angles
if
■*?
/
T
X
Depth
of
Weight
Area
of
Width
of
Thick-
ness
Axis 1—1
Axis 2— 2
per
of
Web
Angle
Foot
Section
Flange
/
S
B
X
/
S
R
V
10
32.0
9.41
3.500
.625
116.0
21.6
3.51
4.62
6.2
2.3
.82
.77
2b. 6
7.80
.484
104.2
19.9
3.66
4.75
5.0
18
.80
.72
9
21.8
6.41
.438
69.3
14.5
3.33
4.21
4.3
1.5
.82
.72
8
19.3
5.66
.406
48 8
11.7
2.95
3.83
3.7
1.3
.81
.71
7
20.0
5.81
3.000
.500
36.6
10.0
2.51
3.34
2.9
1.3
.71
.70
18.3
5.37
.438
34.9
9.6
2.56
3.36
2.6
1.1
.69
.68
16.1
4.71
.b44
32.2
8.7
2.61
3.30
2.7
1.2
.76
.72
6
17.3
5.06
.500
23.9
7.6
2.16
2.84
2.5
1.1
.70
.71
15.0
4.38
.406
21.1
6.7
2.19
2.84
2.3
1.0
.72
.69
13.8
4.04
.375
20.1
6.6
2.21
2.96
1.9
.82
.69
.65
12.4
3.62
.313
18.6
5.7
2.28
2.71
1.8
.75
.70
.64
5
13.2
3.82
3.500
.375
13.5
4.9
1.88
2.22
3.3
1.24
.92
.86
10.0
2.94
2.500
.313
10.2
4.1
1.86
2.49
.95
.49
.57
.57
8.3
2.44
.240
8.6
3.4
1.89
2.41
.91
.47
.61
.55
4V?,
6.7
1.95
2.250
.220
5.6
2.4
1.69
2.12
.60
.34
.56
.50
4
14.3
4.21
3.500
.500
8.7
3.7
1 44
1.65
3.9
1.5
.96
.99
11.9
3.48
.375
7.9
3.5
1.50
1.77
3.1
1.2
.94
.94
3
3.60
1.08
2.000
.190
1.3
.74
1.09
1.24
.31
.20
.54
.45
3.25
.97
1.750
.160
1.2
.72
1.13
1.31
.21
.16
.47
.41
2H
2.66
.84
1.500
.150
.74
.55
.94
1.17
.12
.11
.38
.36
Band Edge Flats
%'
wide
X No
. 18
A'
«
X
19
V*'
u
X
22
A' to
i',
u
X
23
1A' "
2',
u
X
22
2A' «
3',
u
X
21
3A' «
3H',
u
X
20
3A* «
4',
it
X
19
4A' «
4^',
u
X
18
4A' «
5A',
a
X
17
VA" "
6W,
u
X
16
»tt' «
m:
u
X
14
sh' •
9%",
u
X
12
m «
139
Digiti
zed by G00gk
7
Sin
Weight
Foot
Area
of
Sec-
Axis 1-1
Axis 2-2
Minimum
Thickness
Flange
Stem
tion
/
8
B
X
/
8
R
Flange
Stem
4
4
M
8
13.5
3.97
5.7
2.
1.20
1.18
2.8
1.4
.84
H
10.5
3.09
4.5
1.6
1.21
1.13
2.1
1.1
.83
3H
M
H
^
11.7
3.44
3.7
1.5
1.04
1.05
1.9
1.1
.74
%
-a
9.2
2.68
3.0
1.2
1.05
1.01
1.4
.81
.73
3
3
H
9.9
2.91
2.3
1.1
.88
.93
1.2
.80
.64
6
«
8.9
2.59
2.1
.98
.89
.91
1.0
.70
.63
7.8
2.27
1.8
.86
.90
.88
.90
.60
.63
£
ft
6.7
1.95
1.6
.74
.90
.86
.75
.50
.62
2H
2H
6.4
1.87
1.0
.59
.74
.76
.52
.42
.53
A
5.5
1.60
.88
.5
.74
.74
.44
.35
.52
2H
2H
A
ft
•4.9
1.43
.65
.41
.67
.68
.33
.29
.48
Vi
4.1
1.19
.52
.32
.66
.65
.25
.22
.46
2
2
A
4.3
1.26
.44
.31
.59
.61
.23
.23
.43
yi
y^
3.56
1.05
.37
.26
.59
.59
.18
.18
.42
IH
IH
\i
H
3.09
.91
.23
.19
.51
.54
.12
.14
.37
V4
m
i^
X
2.47
.73
.15
.14
.45
.47
.08
.10
.32
|
ft
1.94
.67
.11
.11
.45
.44
.06
.08
.32
IH
1M
2.02
.69
.08
.10
.37
.40
.05
.07
.28
A
1.59
.47
.06
.07
.37
.38
.03
.05
.27
1
1
A,
A
1.25
.37
.03
.05
.29
.32
.02
.04
.22
K
H
.89
.26
.02
.03
.30
.29
.01
.02
.21
Over
3'
u
5'
5*
u
V
V
u
7H*
7W
u
8'
Square Edge Flats
%" to 3" wide X any thickness, y% up to width.
X u u K" to 3', inclusive.
X " " H" tt 2", «
X a u A' u M, "
X u " A' u 1", u
Squares
Size A" to 2", inclusive, advancing by 64ths.
tt 2A' u *Wi u u tt 32nds.
u 3 A' " W, " u a 16ths.
Round Cornered Squares
Size Ji* to Ji", inclusive, advancing by
140
64ths.
Unequal Tehs
12
2F
III
Size
Weight
Foot
Area
of
Sec-
Axis 1-1
A
ois 2-2
Minimum
Thickness
Flange
Stem
tion
/
8
R
X
/
S
R
Flange
Stem
5
3
H
11
13.4
3.. -3
2.4
1.1
.78
.73
5.4
2.2
1.17
2H
N
A
10.9
3.18
1.5
.78
.68
.63
4.1
1.6
1.14
4H
m
A
H
15.7
4.60
5.1
2.1
1.05
1.11
3.7
1.7
.90
3
N
%
9.8
2.88
2.1
.91
.84
.74
3.
1.3
1.02
3
ft
ft
8.4
2.46
1.8
.78
.85
.71
2.5
1.1
1.01
2H
9.2
2.68
1.2
.63
.67
.59
3.
1.3
1.05
2H
ft
A
7.8
2.29
1.
.54
.68
.57
2 5
1.1
1.05
4
5
8
15.3
4.50
10.8
3.1
1.55
1.56
2.8
1.4
.79
5
8
11.9
3.49
8.5
2.4
1.56
1.51
2.1
1.1
.78
4H
II
14.4
4.23
7.9
2.5
1.37
1.37
2.8
1.4
.81
4K
H
11.2
3.29
6.3
2.
1.39
1,31
2.1
1.1
.80
3
H
H
9.2
2.68
2.
.9
.86
.78
2.1
1.1
.89
3
ft
ft
7.8
2.29
1.7
.77
.87
.75
1.8
.88
.88
2H
8.5
2.48
1.2
.62
.69
.62
2.1
1.
.92
2H
ft
ft
7.2
2.12
1.
.53
.69
.6
1.8
.88
.91
2
7.8
2.27
.60
.40
.52
.48
2.1
1.1
96
2
ft
ft
6.7
1.95
.53
.34
.52
.46
1.8
.88
.95
2K
4
12.6
3.70
5.50
2.
1.21
1.24
1.9
1.1
.72
4
K
H
9.8
2.88
4.30
1.5
1.23
1.19
1.4
.81
.70
3
H
H
10.8
3.17
2.4
1.1
.87
.88
1.9
1.1
.77
3
*A
M
8.5
2.48
1.9
.89
.88
.83
1.4
.81
.75
3
ft
H
7.5
2.20
1.8
.85
.91
.85
1.2
.68
.74
3
4
X
11.7
3.44
5 2
1.9
1.23
1.32
1.2
.81
.59
4
ft
ft
10.5
3.06
4.7
1.7
1.23
1.29
1.1
.7
.59
4
9.2
2.68
4.1
1.5
1.24
1.27
.9
.6
.58
M
M
X
10.8
3.17
3.5
1.5
1.06
1.12
1.2
.8
.62
3H
ft
ft
9.7
2.83
3.2
1.3
1.06
1.1
1.
.69
.60
3H
8.5
2.48
2.8
1.2
1.07
1.07
.93
.62
.61
2H
H
H
7.1
2.07
1.1
.6
.72
.71
.89
.59
.66
2H
ft
ft
6.1
1.77
.94
.52
.73
.68
.75
.50
.65
2H
3
7.1
2.07
1.7
.84
.91
.95
.53
.42
.51
3
A
A
6.1
1.77
1.5
.72
.92
.92
.44
.35
.50
IH
ft
ft
2.87
.84
.08
.09
.31
.32
.29
.23
.58
2
3.09
.91
.16
.15
.42
.42
.18
.18
.45
1J4
2
ft
ft
2.45
.72
.27
.19
.61
.63
.06
.08
.92
IK
1.25
.37
.05
.05
.37
.33
.04
.05
.32
IK
^
H
H
.88.
.26
.01
.01
.16
.16
.02
.04
.31
Keys. — For square and flat steel keys, let d = diameter of shaft,
w = width of key, t = thickness, all in inches. Then w = -r + A",
t = o + 14", common taper }4" = V, length 1.5<J.
141
8
Zees
Siae
Weight
Area
of Sec-
tion
Axis 1-1
Axis 2-2
Depth
Flanges
Thickness
Foot
/
s
R
/
S
R
m
3^
H
34.6
10.17
50.2
16.4
2.22
19.2
6.0
1.37
6A
3A
tt
32.0
9.40
46.1
15.2
2.22
17.3
5.5
1.36
6
3»^
%
29.4
8.63
42.1
14.0
2.21
15.4
4.9
1.34
6H
3^
8
28.1
8.25
43.2
14.1
2.29
16.3
5.0
1.41
6^
3A
25.4
7.46
38.9
12.8
2.28
14.4
4.4
1.39
6
3^
A
22.8
6.68
34.6
11.5
2.28
12.6
3.9
1.37
6H
3^
H
21.1
6.19
34.4
11.2
2.36
12.9
3.8
1.44
6*
3A
18.4
5.39
29.8
9.8
2.35
11.0
3.3
1.43
6
3^
%
15.7
4.59
25.3
8.4
2.35
9.1
2.8
1.41
5H
SH
H
28.4
8.33
28.7
11.2
1.86
14.4
4.8
1.31
5A
3ft
/4
26.0
7.64
26.2
10.3
1.85
12.8
4.4
1.30
5
3M
■$
23.7
6.96
23.7
9.5
1.84
11.4
3.9
1.28
w%
3H
H
22.6
6.64
24.5
9.6
1.92
12.1
3.9
1.35
5A
3ft
A
20.2
5.94
21.8
8.6
1.91
10.5
3.5
1.33
5
VA
H
17.9
5.25
19.2
7.7
1.91
9.1
3.0
1.31
5H
3H
A
16.4
4.81
19.1
7.4
1.99
9.2
2.9
1.38
5tV
3ft
H
14.0
4.10
16.2
6.4
1.99
7.7
2.5
1.37
5
3^
11.6
3.40
13.4
5.3
1.98
6.2
2.0
1.35
*H
3ft
23.0
5.75
15.0
7.3
1.49
11.2
4.0
1.29
4A
20.9
6.14
13.5
6.7
1.48
10.0
3.6
1.27
3ft
H
18.9
5.55
12.1
6.1
1.48
8.7
3.2
1.25
4H
3ft
&
18.0
5.27
12.7
6.2
1.55
9.3
3.2
1.33
4A
3H
15.9
4.66
11.2
5.5
1.55
8.0
2.8
1.31
3ft
ft
13.8
4.05
9.7
4.8
1.55
6.7
2.4
1.29
4^
3ft
12.5
3.66
9.6
4.7
1.62
6.8
2.3
1.36
4A
m
ft
10.3
3.03
7.9
3.9
1.62
5.5
1.8
1.34
4 *
3ft
8.2
2.41
6.3
3.1
1.62
4.2
1.4
1.33
3A
3
ft
14.3
4.18
5.3
3.4
1.12
5.7
2.3
1.17
3
12.6
3.69
4.6
3.1
1.12
4.9
2.0
1.15
3*
234
ft
11.5
3.36
4.6
3.0
1.17
4.8
1.9
1.19
3
2tt
9.8
2.86
3.9
2.6
1.16
3.9
1.6
1.17
3*
2H
ft
8.5
2.48
3.6
2.4
1.21
3.6
1.4
1 21
3
2H
6.7
1.97
2.9
1.9
1.21
2.8
1.1
1.19
Hexagons.
Size from flat to flat \i" to If!" inclusive, advancing by 32nds.
a a a a a ^ « 3^ « « a 16thg
a a « a « 3 A*
142
Digiti
zed by G00gk
Weights and Areas of Square and Round Bars and Circum-
ferences of Round Bars
One cubic foot of steel weighs 489.6 lb.
Thickness
or
Diameter
in Inches
Weight of
■ Bar
One Foot
Lome
Weight of
• Bar
One Foot
Long
Area of
■ Bar
in Square
Inches
Area of
• Bar
in Sauare
Inches
Circumfer-
ence of
• Bar
in Inches
A
*
A
.013
.021
.030
.041
.010
.016
.023
.032
.0039
.0061
.0088
.0120
.0031
.0048
.0069
.0094
.1964
.2454
.2945
.3436
1
ft
.053
.067
.083
.100
.042
.053
.065
.079
.0156
.0198
.0244
.0295
.0123
.0155
.0192
.0232
.3927
.4418
.4909
.5400
A
ft
A
ft
.120
.140
.163
.187
.094
.110
.128
.147
.0352
.0413
.0479
.0549
.0276
.02124
.0376
.0431
.5891
.6381 .
.6872
.7363
1
ft
A
ft
.212
.240
.269
.300
•
.167
.188
.211
.235
.0625
.0706
.0791
.0881
.0491
.0554
.0621
.0692
.7854
.8345
.8836
.9327
A
ft
ft
ft
.332
.366
.402
.439
.261
.288
.316
.345
.0977
.1077
.1182
.1292
.0767
.0846
.0928
.1014
.9818
1.0308
1.0799
1.1290
f
ft
H
ft
- .478
.519
.561
.605
.376
.407
.441
.475
.1406
.1526
.1650
.1780
.1104
.1198
.1296
.1398
1.1781
1.2272
1.2763
1.3254
A
ft
ft
ft
.651
.698
.747
.798
.511
.548
.587
.627
.1914
.2053
.2197
.2346
.1503
.1613
.1726
.1843
1.3745
1.4235
1.4726
1.5217
A
H
.850
.904
.960
1.017
.668
.710
.754
.799
.2500
.2659
.2822
.2991
.1963
.2088
.2217
.2349
1.5708
1.6199
1.6690
1.7181
A
II
ft
1.076
1.136
1.199
1.263
.845
.893
.941
.992
.3164
.3342
.3525
.3713
.2485
.2625
.2769
.2916
1.7672
1.8162
1.S653
1.9144
I
1
1.328
1.395
1.464
1.535
1.043
1.096
1.150
1.205
.3906
.4104
.4307
.4514
.3068
.3223
.3382
.3545
1.9635
2.0126
1.0617
2.1108
143
Square and Round Bars — Continued
Thickness
or
Diameter
in Inches
Weight of
■ Bar
One Foot
Long
Weight of
• Bar
One Foot
Long
Area of
■ Bar
in Square
Inches
Area of
#Bar
in Sauare
Inches
Circumfer-
ence of
• Bar
in Inches
1
1.607
1.681
1.756
1.834
1.262
1.320
1.380
1.440
.4727
.4944
.5166
.5393
.3712
.3883
.4057
.4236
2.1599
2.2089
2.2580
2.3071
i
1.913
2.245
2.603
2.988
1.502
1.763
2.044
2.347
.5625
.6602
.7656
.8789
.4418
.5185
.6013
.6903
2.3562
2.5526
2.7489
2.9453
1
A
3.400
3.838
4.303
4.795
2.670
3.015
3.380
3.766
1.0000
1.1289
1.2656
1.4102
.7854
.8866
,9940
1.1075
3.1416
3.3380
3.5343
3.7306
A
A
5.3J3
5.857
6.428
7.026
4.172
4.600
5.049
5.518
1.5625
1.7227
1.8906
2.0664
1.2272
1.3530
1.4849
1.6230
3.9270
4.1234
4.3197
4.5161
A
1
ii
7.650
8.301
8.978
9.682
6.008
6.519
7.051
7.604
2.2500
2.4414
2.6406
2.8477
1.7671.
1.9175
2.0739
2.2365
4.7124
4.9088
5.1051
5.3015
4
4
10.41
11.17
11.95
12.76
8.178
8.773
9.388
10.02
3.0625
3.2852
3.5156
3.7539
2.4053
2.5802
2.7612
2.9483
5.4978
. 5.6942
5.8905
6.0869
2
A
13.60
14.46
15.35
16.27
10.68
11.36
12.06
12.78
4.0000
4.2539
4.5156
4.7852
3.1416
3.3410
3.5466
3.7583
6.2832
6.4796
6.6759
6.8723
A
I
17.21
18.18
19.18
20.20
13.52
14.28
15.06
15.87
5.0625
5.3477
5.6406
5.9414
3.9761
4.2000
4.4301
4.6664
7.0686
7.2650
7.4613
7.6577
i
A
i
ii
21.25
22.33
23.43
24.56
16.69
17.53
18.40
19.29
6.2500
6.5664
6.8906
7.2227
4.9087
5.1573
5.4119
5.6727
7.8540
8.0504
8.2467
8.4431
i
i
25.71
26.90
28.10
29.34
20.19
21.12
22.07
23.04
7.5625
7.9102
8.2656
8.6289
5.9396
6.2126
6.4918
6.7771
8.6394
8.8358
9.0321
9.2285
144
3§k
Square and Round Bars — Continued
Thickness
or
Diameter
in Inches
Weight of
■ Bar
One Foot
Long
Weight of
• Bar
One Foot
Long
Area of
■ Bar
in Square
Inches
Area of
• Bar
in Square
Incnes
Circumfer-
ence of
• Bar
in Inches
3
A
i
A
30.60
31.89
33.20
34.55
24.03
25.05
26.08
27.13
9.0000
9.3789
9.7656
10.160
7.0686
7.3662
7.6699
7.9798
9.4248
9.6212
9.8175
10.014
A
t
A
35.92
37.31
38.73
40.18
28.21
29.30
30.42
31.55
10.563
10.973
11.391
11.816
8.2958
8.6179
8.9462
9.2806
10.210
10.407
10.603
10.799
i
A
■A
41.65
43.15
44.68
46.23
32.71
33.89
35.09
36.31
12.250
12.691
13.141
13.598
9.6211
9.9678
10.321
10.680
10.996
11.192
11.388
11.585
i
*
47.82
49.42
51.05
52.71
37.55
38.81
40.10
41.40
14.063
14.535
15.016
15.504
11.045
11.416
11.793
12.177
11.781
11.977
12.174
12.370
4
. A
A
54.40
56.11
57.85
59:62
42.73
44.07
45.44
46.83
- 16.000
16.504
17; 016
17.535
12.566
12.962
13.364
13.772
12.566
12.763
12.959
13.155
A
i
A
61.41
63.23
65.08
66.95
48.24
49.66
51.11
52.58
18.063
18.598
19.141
19.691
14.186
14.607
15.033
15.466
13.352
13.548
13.745
13.941
i
A
f
14
68.85
70.78
72.73
74.71
54.07
55.59
57.12
58.67
20.250
20.816
21.391
21.973
15.904
16.349
16.800
17.257
14.137
14.334
14.530
14.726
A
J
ii
76.71
78.74
80.80
82.89
60.25
61.85
63.46
65.10
22.563
23.160
23.766
24.379
17.721
18.190
18.665
19.147
14.923 %
15.119
15.315
15.512
5
A
A
85.00
87.14
89.30
91.49
66.76
68.44
70.14
71 86
25.000
25.629
26.266
26.910
19.635
20.129
20.629
21.135
15.708
15.904
16.101
16.297
i
A
1
A
93.71
95.96
98.23
100.5
73.60
75.37
77.15
78.95
27.563
28.223
28.891
29.566
21.648
22.166
22.691
23.221
16.493
16.690
16.886
17.082
145
Digitize
Squab
B and Round Bars1— Continued
Thickness
or
Diameter
in Inches
Weight of
■ Bar
One Foot
Long
Weight of
• Bar
One Foot
Long
Area of
. BBar
in Square
Inches
Area of
• Bar
in Square
Inches
Circumfer-
ence of
• Bar
in Inches
5A
I
102.9
105.2
107.6
110.0
80.78
82.62
84.49
86.38
30.250
30.941
31.641
32.348
23.758
24.301
24.851
25.406
17.279
17.475
17.672
17.868
112.4
114.9
117.4
119.9
88.29
90.22
92.17
94.14
33.063
33.785
34.516
35.254
25.967
26.535
27.109
27.688
18.064
18.261
18.457
18.653
6
A
i
A
122.4
125.0
127.6
130.2
96.13
98.15
101.8
102.2
36.000
36.754
37.516
38.285'
28.274
28.867
29.465
30.069
18.850
19.046
19.242
19.439
1
A
A
132.8
135.5
138.2
140.9
104.3
106.4
108.5
110.7
39.063
39.848
40.641
41.441
30.680
31.296
31.919
32.548
19.635
19.831
20.028
20.224
1
A
i
ii
143.7
146.5
149.2
152.1
112.8
115.0
117.2
119.4
.42.250
43.066
43.891
44.723
33.183
33.824
34.472
35.125-
20.420
20.617
20.813 '
21.009
i
M
J
if
154.9
157.8
1G0.7
1G3.6
121.7
123.9
126.2
128.5
45.563
46.410
47.266
48.129
35.785
36.451
37.122
37.800
21.206
21.402
21.599
21.795
7
A
A
166.6
169.6
172.6
175.6
130.8
133.2
135.6
138.0
49.000
49.879
50.766
51.660
38.485
39.175
39.871
,40.574
21.991
22.188
22.384
22.580
i
A
178.7
181.8
184.9
188.1
140.4
142.8
145.2
147.7
52.563
53.473
54.391
55.316
41.283
41.997
42.718
43.446
22.777
22.973
23.169
23.366
A
i
191.3
194.5
197.7
200.9
150.2
152.7
155.3
157.8
56.250
57.191
58.141
59.098
44.179
44.918
45.664
46.415
23.562
23.758
23.955
24.151
1
i
H
204.2
207.5
210.9
214.2
160.4
163.0
165.6
168 .2
60.063
61.035
62.016
63 004
47.173
47.937
48.707
49.483
24.347
24.544
24.740
24.936
146
Digitized by VJ vJvJ V LV^
Square and Round Bars — Continued
Thickness
or
Diameter
in Inches
Weight of
■ Bar
One Foot
Long
Weight of
• Bar
One Foot
Long
Area of
■ Bar
in Square
Inches
Area of
• Bar
in Square
Inches
Circumfer-
ence of
• Bar
in Inches
8
A
i
A
217.6
221.0
224.5
227.9
170,. 9
173.6
176.3
179.0
64.000
65.004
66.016
67.035
50.266
51.054
51.849
52.649
25.133
25.329
25.526
25.722
i
A
i
A
231.4
234.9
238.5
242.1
181.8
184.5
187.3
190.1
68.063
69.098
70.141
71 . 191
53.456
54.269
55.088
55.914
25.918
26.115
26.311
26.507
A
i
245.7
249.3
252.9
256.6
192.9
195.8
198.6
201.5
72.250
73.316
74.391
75.473
56.745
57.583
58.426
59.276
26.704
26.900
27.096
27.293
J
260.3
264.0
267.8
271.6
204.4
207.4
210.3
213.3
76.563
77.660
78.766
79.879
60.132
60.994
61.863
62.737
27.489
27.685
27.882
28.078
9
A
I
A
275.4
279.2
283.1
287.0
216.3
219.3
222.3
225.4
81.000
82.129
83.266
84.410
63.617
64.504
65.397
66.296
28.274
28.471
28.667
28.863 •
1
A
i
A
290.9 .
294.9
298.8
302.8
228.5
231.6
234.7
237.8
85.563
86.723
87.891
89.066
67.201
68.112
69.029
69.953
29.060
29.256
29.453
29.649
A
t
306.9
310.9
315.0
319.1
241.0
244.2
247.4
250.6
90.250
91.441
92.641
93.848
70.882
71.818
72.760
73.708
29.845
30.042
30.238
30.434
i
323.2
327.4
331.6
335.8
253.8
257.1
260.4
263.7
95.063
96.285
97.516
98.754
74.662
75.622
76.589
77.561
30.631
30.827
31.023
31.220
10
A
A
340.0
344.3
348.6
352.9
267.0
270.4
273.8
277.1
100.00
101.25
102.52
103.79
78.540
79.525
80.516
81.513
31.416
31.612
31.809
32.005
i
A
1
357.2
361.6
366.0
370.4
280.6
284.0
287.4
290.9
105.06
106.35
107.64
108.94
82.516
83.525
84.541
85.563
32.201
32.398
32.594
32.790
117
Square and Round Bars — Continued
Thickness
or
Diameter
in Inches
Weight of
■ Bar
One Foot
Long
Weight of
• Bar
One Foot
Long
Area of
■ Bar
in Square
Inches
Area of
• Bar
in ►Square
Inches
Circumfer-
ence of
• Bar
in Inches
10 i
1'
374.9
379.3
383.8
388.4
294.4
297.9
301.5
305.0
110.25
111.57
112.89
114.22
86.590
87.624
88.664
89.710
32.987
33.183
33.380
33.576
i
i
392.9
397.5
402.1
406.7
308.6
312.2
315.8
319.5
115.56
116.91
118.27
119.63
90.763
91.821
92.886
93.957
33.772
33.969
34.165
34.361
u
*
i
A
411.4
416.1
420.8
425.5
323.1
326.8
330.5
334.3
121.00
122.38
123.77
125.16
95.033
96.116
97.206
98.301
34.558
34.754
34.950
35.147
1
430.3
435.1
439.9
444.8
338.0
341.7
345.5
349.3
126.56
127.97
129.39
130.82
99.402
100.51
101.62
102.74
35.343
35.539
35.736
35.932
i
f
tt
449.7
454.6
459.5
464.4
353.2
357.0
360.9
364.8
132.25
133.69
135.14
136.60
103.87
105.00
106.14
107.28
36.128
36.325
36.521
36.717
1
469.4
474.4
479.5
484.5
368.7
372.6
376.6
380.5
138.06
139.54
141.02
142.50
108.43
109.59
110.75
111.92
36.914
37.110
37.307
37.503
From Handbook, Cambria Steel Co.
Notes on Gearing. — Circular pitch =
_ 3.1416 X dia. ins.
; diaraet-
number of teeth
• • number of teeth
ical pitch = dja of pitch circle in ing
Formulae for Gears. Two gears are to run together, and for
the large let D = diameter of pitch circle, D = whole diameter,
N = number of teeth, V = velocity, and for the small d — diameter
of pitch circle, d = whole diameter, n = number of teeth, v = veloc-
ity. Also let a = distance between centers of the two wheels, 6 =
number of teeth in both wheels. Then N= ^ ; n == — 1_; V =
V v + V
Vil - NV ♦ D'= 2av - D =2ajnjf_2). ,/= 2aV
N ' n ' v+V ' 6 v+V
* Brown and Sharpe Mfg. Co.
148
Digiti
zed by G00gk
Weights of Flat Rolled Steel Bars
Pounds per Lineal Foot
One cubic foot of steel weighs 489.6 pounds
For thicknesses from ft in. to 2 ins. and widths from 1 in. to 12% ins.
Thickness
in Inches
1*
IK*
IK0
IH"
2*
2X*
2X*
2X"
12»
ft
.638
.850
.797
1.06
.956
1.28
1.12
1.49
1.28
1.70
1.43
1.91
1.59
2.13
1.75
2.34
7.65
10.20
A
X
ft
1.06
1.28
1.49
1.70
1.33
1.59
1.86
2.13
1.59
1.91
2.23
2.55
1.86
2.23
2.60
2.98,
2.13
2.55
2.98
3.40
2*39
2.87
3.35
3.83
2.66
3.19
3.72
4.25
2.92
3.51
4.09
4.68
12.75
15.30
17.85
20.40
i
1.91
2.13
2.34
2.55
2.39
2.66
2.92
3.19
2.87
3.19
3.51
3.83
3.35
3.72
4.09
4.46
3.83
4.25
4.68
5.10
4.30
4.78
5.26
5.74
4.78
5.31
5.84
6.38
5.26
5.84
6.43
7.01
22.95
25.50
28.05
30.60
IS
a
i
2.76
2.98
3.19
3.40
3.45
3.72
3.98
4.25
4.14
4.46
4.78
5.10
4.83
5.21
5.58
5.95
5.53
5.95
6.38
6.80
6.22
6.69
7.17
7.65
6.91
7.44
7.97
8.50
7.60
8.18
8.77
9.35
33.15
35.70
38.25
40.80
1A
IX
1A
IX
3.61
3.83
4.04
4.25
4.52
4.78
5.05
5.31
5.42
5.74
6.06
6.38
6.32
6.69
7.07
7.44
7.23
7.65
8.08
8.50
8.13
8.61
9.08
9.56
9.03
9.56
10.09
10.63
9.93
10.52
11.10
11.69
43.35
45.90
48.45
51.00
1A
IX
1ft
4.46
4.68
4.89
5.10
5.58
5.84
6.11
6.38
6.69
7.01
7.33
7.65
7.81
8.18
8.55
8.93
8.93
9.35
9.78
10.20
10.04
10.52
11.00
11.48
11.16
11.69
12.22
12.75
12.27
12.86
13.44
14.03
53.55
56.10
58.65
61.20
ltt
1%
5.31
5.53
5.74
5.95
6.64
6.91
7.17
7.44
7.97
8.29
8.61
8.93
9.30
9.67
10.04
10.41
10.63
11.05
11.48
11.90
11.95
12.43
12.91
13.39
13.28
13.81
14.34
14.8a
14.61
15.19
15.78
16.36
63.75
66.30
68.85
71.40
itt
2
6.16
6.38
6.59
6.80
7.70
7.97
8.23
8.50
9.24
9.56
9.88
10.20
10.78
11.16
11.53
11.90
12.33
12.75
13.18
13.60
13.87
14.34
14.82
15.30
15.41
15.94
16.47
17.00
16.95
17.53
18.12
18.70
73.95
76.50
79.05
81.60
149
Digiti
zed by G00gk
Weights of Flat Rolled Steel Bars — Continued
Thickness
in Inches
3K"
SlA"
WS
±K"
4W
W
\2"
A
X
A
H
A
H
9
%
J*
H
Vs
a
1A
1M
1A
i«
1A
1J*
1A
i%
1H
lJi
1H'
IK
1H
2
1.91
2.55
3.19
3.83
4.46
5.10
5.74
6.38
7.01
7.65
8.29
8.93
9.56
10.20
10.84
11.48
12.11
12.75
13.39
14.03
14.66
15.30
15.92
16.58
17.21
17.85
18.49
19.13
19.76
20.40
2.07
2.76
3.45
4. -14
4.83
5.53
6.22
6.91
7.60
8.29
8.98
9.67
10.36
11.05
11.74
12.43
13.12
13.81
14.50
15.19
15.88
16.58
17.27
17.96
18.65
19.34
20.03
20.72
21.41
22.10
2.23
2.98
3.72
4.46
5.21
5.95
6.69
7.44
8.18
8.93
9.67
10.41
11.16
11.90
12.64
13.39
14.13
14.88
15.62
16.36
17.11
17.85
18.59
19.34
20.08
20.83
21.57
22.31
23.06
23.80
2.39
3.19
3.98
4.78
5
6
7.17
7.97
8.77
9.56
10.36
11.16
11.95
12.75
13.55
14.34
15.14
15.94
16.73
17.53
18.33
19.13
19.92
20.72
21.52
22.31
23.11
23.91
24.70
25.50
2.55
3.40
4.25
5.10
5.95
6.80
7.65
8.50
9.35
10.20
11.05
11.90
12.75
13.60
14.45
15.30
16.15
17.00
17.85
18.70
19.55
20.40
21.25
22.10
22.95
23.80
24.65
25.50
26.35
27.20
2.71
3.61
4.52
5.42
6.32
7.22
8.13
9.03
9.93
10.84
11.74
12.64
13.55
14.45
15.35
16.26
17.16
18.06
18.97
19.87
20.77
21.68
22.58
23.48
24.38
25.29
26.19
27.09
28.00
28.90
2.87
3.83
4.78
5.74
6.69
7.65
8.61
9.56
10.52
11.48
12.43
13.39
14.34
15.30
16.26
17.21
18.17
19.13
2Q.08
21.04
21.99
22.95
23.91
24.86
25.82
26.78
27.73
28.69
29.64
30.60
3.03
4.04
5.05
6.06
7.07
8.08
9.08
10.09
11.10
12.11
13.12
14.13
15.14
16.15
17.16
18.17
19.18
20.19
21.20
22.21
23.22
24.23
25.23
26.24
27.25
28.26
29.27
30.28
31.29
32.30
7.65
10.20
12.75
15.30
17.85
20.40
22.95
25.50
28.05
30.60
33.15
35.70
38.25
40.80
43.35
45.90
48.45
51.00
53.55
56.10
58.65
61.20
63.75
66.30
68.85
71.40
73.95
76.50
79.05
81.60
150
Digiti
zed by G00gk
Weights op Flat Rolled Steel Bars — Continued
Thickness
in Inches
5H"
W
5K"
W
GX"
W
12"
A
X
A
H
A
K
A
k
»
K
H
K
1A
IK
1A
IK
1A
IK
1A
IK
1A
IK
1H
IK
1H
IK
1H
2
3.19
4.25
5.31
6.38
7.44
8.50
9. 50
10.63
11.69
12.75
13.81
14.88
15.94
17.00
18.06
19.13
20.19
21.25
22.31
23.38
24.44
25.50
26.56
27.63
28.69
29.75
30.81
31.88
32.94
34.00
3.35
4.46
5.58
6.69
7.81
8.93
10.04
11.16
12.27
13.39
14.50
15.62
16.73
17.85
18.97
20.08
21.20
22.31
23.43
24.54
25 .'66
26.78
27.89
29.01
30.12
31.24
32.35
33.47
34.58
35.70
3.51
4.68
5.84
7.01
8.18
9.35
10.52
11.69
12.86
14.03
15.19
16.36
17.53
18.70
19.87
21.04
22.21
23.38
24.54
25.71
26.88
28.05
29.22
30.39
31.56
32.73
33.89
35.06
36.23
37.40
3.67
4
6.11
7.33
8.55
9.78
11.00
12.22
13.44
14.67
15.88
17.11
18.33
19.55
20.77
21.99
23.22
24.44
25.66
26.88
28.10
29.33
30.55
31.77
32.99
34.21
35.43
36.66
37.88
39.10
3.83
5.10
6.38
7.65
8.93
10.20
11.48
12.75
14.03
15.30
16.58
17.85
19.13
20.40
21.68
22.95
24.23
25.50
26.78
28.05
29.33
30.60
31.88
33.15
34.43
35.70
36.98
38.25
39.53
40.80
3.98
5.31
6.64
7.97
9.30
10.63
11.95
13.28
14.61
15.94
17.27
18.59
19.92
21.25
22.58
23.91
25.23
26.56
27.89
29.22
30.55
31.88
33.20
34.53
35.86
37.19
38.52
39.84
41.17
42.50
4.14
5.53
6.91
8.29
9.67
11.05
12.43
13.81
15.19
16.58
4.30
5.74
7.17
8.61
10.04
11.48
12.91
14.34
15.78
17.21
17.
19.34
20.72
22.10
23.48
24.86
26.24
27.63
29.01
30.39
31.77
33.15
34.53
35.91
37.29
38.68
40.06
41.44
42.82
44.20
9618
65
20.08
21.52
22.95
24.38
25.82
27.25
28.69
30.12
31.56
32.99
34.43
35.86
37.29
38.73
40.16
41.60
43.03
44.47
45.90
7.65
10.20
12.75
15.30
17.85
20.40
22.95
25.50
28.05
30.60
33 ..15
35.70
38.25
40.80
43.35
45.90
48.45
51.00
53.55
56.10
58.65
61.20
63.75
66.30
68.85
71.40
73.95
76.50
79.05
81.60
151
Digiti
zed by G00gk
Weights op Flat Rolled Steel Bars — Continued
Thickness
in Inches
7X"
7H"
7H"
W
8H*
8K'
12»
X
A
H
A
K
1
1A
i«
1A
IK
1A
1H
1A
1H
1A
1H
2
4.46
5.95
7.44
8.93
10.41
11.90
13.39
14.88
16.36
17.85
19.34
20.83
22.31
23.80
25.29
26.78
28.26
29.75
31.24
32.73
34.21
35.70
37.19
38.68
40.16
41.65
43.14
44.63
46.11
47.60
4.62
6.16
7.70
9.24
10.78
12.33
13.87
15.41
16.95
18.49
20.03
21.57
23.11
24.65
26.19
27.73
29.27
30.81
32.35
33.89
35.43
36.98
38.52
40.06
41.60
43.14
44.68
46.22
47.76
49.30
4.78
6.38
7.97
9.56
11.16
12.75
14.34
15.94
17.53
19.13
4.94
6.59
8.23
9.88
11.53
13.18
14.82
16.47
18.12
19.76
20.72
22.31
23.9lf24
25.50
21.41
23.06
24.70
26.35
27.09
28.69
30.28
31.88
33.47
35.06
36.66
38.25
39.84
41.44
43.03
44.63
46.22
47.81
49.41
51.00
28.00
29.64
31.29
32.94
34.58
36.23
37.88
39.53
41.17
42.82
44.47
46.11
47.76
49.41
51.05
52.70
5.10
6.80
8.50
10.20
11.90
13.60
15.30
17.00
18.70
20.40
22.10
23.80
25.50
27.20
28.90
30.60
32.30
34.00
35.70
37.40
39.10
40.80
42.50
44.20
45.90
47.60
49.30
51.00
52.70
54.40
5.26
7.01
8.77
10.52
12.27
14.03
15.78
17 53
19.28
21.04
22.79
24.54
26.30
28.05
29.80
31.56
33.31
35.06
36.82
38.57
40.32
42.08
43.83
45.58
47.33
49.09
50.84
52.59
54.35
56.10
5.42
7.23
9.03
10.84
12.64
14.45
16.26
18.06
19.87
21.68
23.48
25.29
27.09
28.90
30.71
32.51
34.32
36.13
37.93
39.74
41.54
43.35
45.16
46.96
48.77
50.58
52.38
54.19
55.99
57.80
5.58
7.44
9.30
11.16
13.02
14.88
16.73
18.59
20.45
22.31
24.17
26.03
27.89
29.75
31.61
33.47
35.33
37.19
39.05
40.91
42.77
44.63
46.48
48.34
50.20
52.06
53.92
55.78
57.64
59.50
7.65
10.20
12.75
15.30
17.85
20.40
22.95
25.50
28.05
30.60
33.15.
35.70
38.25
40.80
43.35
45.90
48.45
51.00
53.55
56 . 10
58.65
61.20
63.75
66.30
68.85
71.40
73.95
76.50
79.05
81.60
152
Digiti
zed by G00gk
Weights op Flat Rolled Steel Bars — Continued
Thickness
in Inches
W
9X"
W
10*
10K"
10H"
10M*
12"
ft
ft
ft
lA
lA
lJi
lA
i»
lA
134
1A
i«
1H
1%
1H
i«
1H
2
5.74
7.65
9.56
11.48
13.39
15.30
17.21
19.13
21.04
22.95
24.86
26.78
28.69
30.60
32.51
34.43
36.34
38.25
40.16
42.08
43.99
45.90
47.81
49.73
51.64
53.55
55.46
57.38
59.29
61.20
5.90
7
9.83
11.79
13.76
15.73
17.69
19.66
21.62
23.59
25.55
27.52
29.48
31.45
33.42
35.38
37.35
39.31
41.28
43.24
45.21
47.18
49.14
51.11
53.07
55.04
57.00
58.97
60.93
62.90
6.06
8.08
10.09
12.11
14.13
16.15
18.17
20.19
22.21
24.23
26.24
28.26
30.28
32.30
34.32
36.34
38.36
40.38
42.39
44.41
46.43
48.45
50.47
52.49
54.51
56.53
58.54
60.56
62.58
64.60
6.22
8.29
10.36
12.43
14.50
16.58
18.65
20.72
22.79
24.86
26.93
29.01
31.08
33.15
35.22
37.29
39.37
41.44
43.51
45.58
47.65
49.73
51.80
53.87
55.94
58.01
60.08
62.16
64.23
66.30
6.38
8.50
10.63
12.75
14.88
17.00
19.13
21.25
23.38
25.50
27.63
29.75
31.88
34.00
36.13
38.25
40.38
42.50
44.63
46.75
48.88
51.00
53.13
55.25
57.38
59.50
61.63
63.75
65.88
68.00
6.53
8.71
10.89
13.07
15.25
17.43
19.60
21.78
23.96
26.14
28.32
30.49
32.67
34.85
37.03
39.21
41.38
43.56
45.74
47.92
,50.10
52.28
54.45
56.63
58.81
60.99
63.17
65.34
67.52
69.70
6.69
8.93
11.16
13.39
15.62
17.85
20.08
22.31
24.54
26.78
29.01
31.24
33.47
35.70
37.93
40.16
42.39
44.63
46.86
49.09
51.32
53.55
55.78
58.01
60.24
62.48
64.71
66.94
69.17
71.40
6.85
9.14
11.42
13.71
15.99
18.28
20.56
22.84
25.13
27.41
29.70
31.98
34.27
36.55
38.83
41.12
43.40
45.69
47.97
50.26
52.54
54.83
57.11
59.39
61.68
63.96
66.25
68.53
70.82
73.10
7.65
10.20
12.75
15.30
17.85
20.40
22.95
25.50
28.05
30.60
33.15
35.70
38.25
40.80
43.35
45.90
48.45
51.00
53.55
56.10
58.65
61.20
63.75
66.30
68:85
71.40
73.95
76.50
79.05
81.60
153
Digiti
zed by G00gk
Weights of Flat Rolled Steel Bars — Continued
Thickness
in Inches
A
k
X
H
H
tt
1A
V/s
1A
lJi
1A
i«
1A
1A
i«
Hi
IX
1H
IK
itt
2
11*
7.01
9.35
11.69
14.03
16.36
18.70
21.04
23.38
25.71
28.05
30.39
32.73
35.06
37.40
39.74
42.08
44. 41
46.75
49.09
51.43
53.76
56.10
58.44
60.78
63.11
65.45
67.79
70.13
72.46
74.80
11M"
7.17
9.56
11.95
14.34
16.73
19.13
21.52
23:91
26.30
28.69
31.08
33.47
35.86
38.25
40.64
43.03
45.42
47.81
50.20
52.59
54.98
57.38
59.77
62.16
64.55
66.94
69.33
71.72
74.11
76.50
IW
7.33
9.78
12.22
14.66
17.11
19.55
21.99
24.44
26.88
29.33
31.77
34.21
36.66
39.10
41.54
43.99
46.43
48.88
51.32
53.76
56.21
58.65
61.09
63.54
65.98
68.43
70.87
73.31
75.76
78.20
llM"
7.49
9.99
12.48
14.98
17.48
19.98
22.47
24.97
27.47
29.96
32.46
34.96
37.45
39.95
42.45
44.94
47.44
49.94
52.43
54.93
57.43
59.93
62.42
64.92
67.42
69.91
72.41
74.91
77.40
79.90
7.65
10.20
12.75
15.30
17.85
2Q. 40
22.95
25.50
28.0.r
30.60
33.15
35.70
38.25
40.80
43.35
45.90
48.45
51.00
53.55
56.10
58.65
61.20
63.75
66.30
68.85
71.40
73.95
76.50
79.05
81.60
12H"
7.81
10.41
13.02
15.62
18.22
20.83
23.43
26.03
28.63
31.24
33.84
36.44
39.05
41.65
44.25
46.86
49.46
52.06
54.67
57.27
59.87
62.48
65.08
67.68
70.28
72.89
75.49
78.09
80.70
83.30
12^*
7.97
10.63
13.28
15.94
18.59
21.25
23.91
26.56
29.22
31.88
34.53
37.19
39.84
42.50
45.16
47.81
50.47
53.13
55.78
58.44
61.09
63.75
66.41
69.06
71.72
74.38
77.03
79.69
82.34
85.00
12H"
8.13
10.84
13.55
16.26
18.97
31.68
3g«
c a r~
11
s:
g>«eoS
ft+* fcio
* *.g ft
*"' in O O
Slat
o 03 a
154
Digiti
zed by G00gk
METALS AND ALLOYS 155
NON-FERROUS METALS AND ALLOYS
Copper. — There are three recognized grades, viz., electrolytic,
Lake, and casting. The first is refined by electrolytic methods
and is very pure. Lake is also very pure in its natural or mineral
state and requires simply to be melted down to bars for convenient
handling. Casting copper contains more impurities and runs lower
in conductivity than either electrolytic or Lake.
Copper is very ductile and malleable and can be rolled into sheets,
drawn into wire, or cast. Electric conductivity equal to that of
silver fuses at around 1930° F. Cast copper tensile strength 25,000,
elastic limit 6,000, copper plates, rods and bolts tensile strength
33,500, elastic limit 10,000, annealed wire 36,000 tensile strength
and elastic limit 10,000. Weight per cubic foot 554 lb. Sp. gr. 8.9.
Aluminum. — A very light and non-corrosive metal that is soft,
ductile and malleable. Is acted on by salt water. The tensile
strength can be increased by cold rolling, and is about the same
as for cast iron. Aluminum castings have a tensile strength of
about 15,000 lb. and elastic limit 6,500, sheets 24,000 and 12,000,
bars 28,000 and 14,000. Weight per cubic foot 159 lb. Sp. gr.
2.56. Can be welded by electricity.
Zinc is practically non-corrosive in the atmosphere, hence is
suitable for a coating for iron and steel surfaces exposed to the
weather. See Galvanizing. Is ductile and malleable but to a
less extent than copper. Melts at 780° F. Weight per cubic foot
436 lb. Sp. gr. 7.14.
Lead is a very malleable and ductile metal, but it is difficult
to draw it into wire. Is rolled in sheets and pipe. Has* a low
tensile strength and elastic limit, hence lead pipes are only for
low pressures. They are not affected by water containing car-
bonates or sulphates as a film of insoluble salt is formed which
prevents action. Tensile strength 1,600 to 2,400 lb. Melts at
620° F. Weight per cubic foot 709 lb. Sp. gr. 11.07.
Tin is a white malleable metal that is not oxidized by moist air.
It melts at 450° F., and is often used for safety plugs in boilers
and also for protecting iron and copper from moisture. Weight
per cubic foot 455 lb. Sp. gr. 7.3.
Bronzes. — Alloys of copper and tin with sometimes other metals
added. Bronze as ordinarily understood is an alloy of copper
and tin varying from 8 to 25% of tin. Average weight 530 lb.
per cubic foot. Sp. gr. 8.62. Gun metal contains 8 to 10% tin,
Digitized by VjiOOQ 1C
156 SHIPBUILDING MATERIALS
and the metal in bells 25%. Cast gun metal, according to U. S.
Navy Dept. specifications, contains 87-89% copper, 9-11% tin,
1-3% zinc, iron not to exceed .06% and lead not over .2%.
Minimum tensile strength 30,000 lb.
Phosphor Bronze. — The strength varies with the percentage of
copper, tin, lead and phosphorus. The following may be taken
as a fair average, 82.2% copper, 12.95% tin, 4.28% lead and .52%
phosphorus. Stems, sternposts and outboard castings of sheathed
and composite vessels are made of it. It is harder, closer-grained
and stronger than Admiralty bronze, has a tensile strength of
about 50,000, elastic limit 24,000. Weight per cubic foot 508 lb.
Sp. gr. 8.
Admiralty Bronze for propeller blades, etc., in the British Navy,
is a mixture of 87% copper, 8% tin and 5% zinc. Average tensile
strength 32,000 lb., with an elongation of 7J^% in 2 ins. Sp. gr:
8.66.
Titan Bronze is an alloy of copper and zinc having the color of
gold. Can be forged from a cherry red heat down to a black heat,
while ordinary brass is only slightly malleable. It resists corro-
sion better than brass and is suitable for pump plungers, propeller
bolts, motor boat shafts, etc. Castings have a tensile strength of
60,000 to 63,000 lb., elastic limit 35,000 to 40,000 lb. per square
inch, elongation 15 to 20% in 2 ins.' May be obtained in bars, in
which case it has a tensile strength of 70,000 to 80,000, elastic
limit 40,000 to 48,000, elongation 40% in 2 ins., reduction of area
45 to 50%.
Tobin Bronze is not affected by salt water, hence is suitable for
propeller shafts of motor boats, valve stems and for other pur-
poses where a strong material is required that is not acted on by
salt water. Contains 59 to 63% copper, % to 1H% tin and re-
mainder zinc. Tensile strength 60,000 to 65,000, compression
170,000 to 180,000. Weight per cubic foot 525 lb. Sp. gr. 8.4.
Manganese Bronze contains 56% copper, about 41% zinc and
small quantities of iron, tin, aluminum and manganese. Used for
outboard castings of sheathed and composite vessels. Tensile
strength 60,000.
Brasses. — These consist of alloys of copper and zinc, the per-
centage of zinc varying from 10 to 50%. Brass castings have a
tensile strength of 26,000 to 31,000 lb., but when the percentage
of zinc exceeds about 45% the tensile strength falls off to around
20,000. Average weight per cubic foot 505 lb. Sp. gr. 8.10.
ioogle
WOOD
157
Muntz Metal is a brass containing 60% copper and 40% zinc.
When rolled and annealed it has the properties of steel, being both
malleable and strong, having a tensile strength of 50,000 to 65,000.
Naval Brass contains 62% copper, 36 to 37% zinc and 1 to llA%
tin. Is not affected by salt water. When rolled into rods accord-
ing to the U. S. Navy requirements it must show a tensile strength
of at least 60,000, an elastic limit of at least lA the ultimate strength
and an elongation of not less than 25% in two inches.
Common Allots
Alloy
Admiralty bronze
Aluminum bronze
Babbitt (light)
Babbitt (heavy)
Brass (common yellow metal)
Brazing metal
Gun metal
Manganese bronze
Muntz metal
Navy brass
Navy composition
Parsons white metal. ,
Phosphor bronze
Steam metal
Tobin bronze.
White metal
Proportions
Copper 87, tin 8, zinc 5
Copper 89 to 98, aluminum 11 to 2
Copper 1.8, tin 89.3, antimony 8.9
Copper 3.7, tin 88.9, antimony 7.4
Copper 65.3, zinc 32.7, lead 2
Copper 84, zinc 16
Copper 89, zinc 2.75, tin 8.25
Copper 88.64, zinc 1.57, tin 8.7, iron
.72, lead .3
Copper 60, zinc 40
Copper 62, zinc 37, tin 1
Copper 88, zinc 2, tin 10
Copper 1.68, zinc 22.9, tin 72.9, lead
1.68, antimony .84
Copper 90 to 92, phosphide of tin
10 to 8
Copper 85, tin 6.5, zinc 4.5, lead 4.25
Copper 59 to 61, tin 1 to 2, zinc 37
to 38, iron .1 to .2, antimony .30
to .35
Antimony 12, lead 88
Weights of Copper and Brass Sheets, see pages 126 and 127.
WOOD
Sawing. — The manner in which lumber is sawed has considerable
influence on its qualities. By flat sawing is meant cutting the
timber tangential to the annual rings. Rift or quarter sawing is
cutting the boards out of a log so the annular rings are cut as nearly
as possible in a radial direction. Flat sawing and rift sawing
give rise in the trade to the terms "flat grain" and "edge grain"
Jle
158
SHIPBUILDING MATERIALS
respectively. Rift sawing is done for the sake* of the beauty of
the grain, and furthermore the lumber shrinks less, does not sliver,
and wears more evenly and smoother than flat grain.
All timber when first cut contains a large quantity of moisture
that must be got rid of by seasoning. Seasoning is either by
natural means, as by leaving the timber exposed to a free circu-
lation of air, or by artificial, as by putting it in a kiln. As a whole
the former gives better results than the latter. The drier the
timber the less likely it is to shrink and decay.
In general, the term "soft wood" is given to all trees of the
coniferous or needle-leaved family, as pines, firs, spruces, hemlocks,
cypress, larch, redwood, cedars, etc. The term "hard wood" is
commonly applied to the broad-leaved family, as oaks, maples,
hickories, elms, basswood, beech, walnut, birch, etc. In the U. S.
Forestry Service hardness is determined by the weight required to
force a steel ball .444 of an inch in diameter one-half its diameter
into the wood. Tests of woods are given in the following table,
the species being arranged from the softest to the hardest as ex-
pressed by the pressure in pounds necessary to make the required
indentation.
As no two trees of the same species are exactly alike, the weights,
strength, and other properties as given in the tables may vary
within rather wide limits, so in making comparisons and in all
strength calculations an ample factor of safety should be taken.
Hardness of Various Woods
Pressure in pounds required to indent specimen to depth of one-
half diameter of a .444-inch diameter steel ball.
Soft Woods
Fir, Alpine 219
Spruce, Englemann. . , 243
Cedar, Western Red 246
Cedar, Northern White. . . 266
Pine, White 296
Pine, Lodgepole 315
Pine, Western Yellow 320
Pine, Sugar 324
Fir, White 328
Pine, Table Mountain .... 333
Pine, Norway 342
Spruce, Red 346
Cypress 354
Tamarack 375
Fir, Grand 375
Hemlock, Eastern 406
Douglas Fir ,408
Hemlock, Black 464
Pine, Longleaf 512
Average hardness, 340
Digitized by LiOOQ 1C
HARD WOOD SIZES
159
Hard Woods
Basswood
Buckeye, Yellow.
Willow, Black . . .
Butternut
Cherry, Red
Elm, White
Ash, Black
Sycamore
Maple, Silver
Maple, Red
Cherry, Black . . .
Tupelo
Birch, Yellow
242
286
334
386
386
511
548
580
592
612
664
700
745
Ash, Pumpkin
Beech
Maple, Hard
Elm, Rock
Ash, White
Oak, Red
Oak, White
Oak, Swamp White .
Laurel, Mountain. . .
Dogwood.
Locust, Black
Locust, Honey
Osage, Orange
752
824
882
888
941
982
1063
1158
1299
1408
1568
1846
2037
Average hardness, 844
Hard Wood Sizes
The standard sizes adopted by the National Hardwood Lumber
Association are as follows:
Standard lengths are 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16
ft., but not over 15% of odd lengths are admitted.
Standard thicknesses are H, %, A, %, %, 1, 1^, IK, 1%, 2,
2J4 3, SA, 4, 4^, 5, 5A and 6 ins.
Standard thicknesses for surfaced lumber are:
Rough
Surfaced
% ins. S-2-S* to A ins.
A " A
% " A
K " A
1 " tt
1A " 1A
VA " 1H
Rough
Surfaced
VA ins. S-2-S to 1^ ins.
2 " lJi
2H " 2H
3 " 2%
*A " ZH
4 " 3%
* S-2-S signifies surfaced on 2 sides.
Lumber surfaced one side only must be A inch full of the
above thicknesses.
The standard sizes for hardwood lumber surfaced two sides
adopted by the Hardwood Manufacturers' Association are as above,
except that these manufacturers work %-in. stock to A-in. instead
of A-in.
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160 SHIPBUILDING MATERIALS
Soft Wood Sizes
The standard lengths of soft woods are commonly in multiples
of 2 ft., beginning at 4 or 6 ft., and standard widths in multiples
of 2 ins., beginning at 4 ins.
Common Woods.1 — Ash, white and red, the former often used for
oars, is close grained, takes a good polish and warps very little.
Weight per cubic foot 43 to 45 lb. Sp. gr. .75. Crushing strength
along the fiber in pounds per square inch, 5,000 to 9,000.
Balsa, very light-; life preservers are sometimes made of it.
Black walnut, heavy, strong and durable; for cabinet work and
interior, decoration. Weight per cubic foot 38 lb. Sp. gr. .61.
Cedar (red), fine grained, strong, easily split, especially durable
in contact with water. Used for planking in high grade motor
boats. Weight per cubic foot 20 to 25 lb. Sp. gr. .33. There is
also a white cedar that is soft, light and fine grained but lacking the
strength and toughness of the red.
Cherry, for interior finish, has a close fine grain, and is very
durable. Weight per cubic foot 42 lb. Sp. gr. ^70.
Chestnut, comparatively soft, close grained, is brittle, but is
durable when exposed to the weather. Weight per cubic foot
28 lb. Sp. gr. .45.
Cork, a tree growing in Southern Europe, the bark of which is
used in life preservers and for insulation purposes in refrigerating
rooms. To avoid sweating in cabins below a steel deck the plating
may be coated with granulated cork. First a coat of sticky varnish
is applied, then the cork dusted thickly over it and painted with
two or three coats of white paint. Weight per cubic foot 15.6 lb.
Sp. gr. .24.
Cypress, light, hard, close grained and durable, adapted for both
outside and inside work. Weight per cubic foot 30 lb. Sp. gr. .48.
Douglas fir. — This term covers the timber known as yellow fir,
red fir, western fir, Washington fir, Oregon or Puget Sound fir,
northwest and west coast fir. Crushing strength parallel to grain
2,920 lb. per square inch. Weight per cubic foot 34 lb. Sp. gr.
.54. Douglas fir is exceptionally strong for its weight, is durable
and does not shrink much.
1 Note. — Only those are given that are common in ship construction. The
specific gravity and weight of the same wood varies; the value given is a fair
average for seasoned wood. The moisture contents varies in seasoned timber from
15 to 20% and in green timber up to 50%. Sp. gr. and weight from 10th U. 8.
Census.
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HACKMATACK 161
Hackmatack, a strong wood for knees connecting beams and
frames of wood vessels. Weight per cubic foot 35 to 40 lb. Sp.
gr. .59.
Lignum vitas, hard, strong and close grained with fibers running
radially and tangentially. Is resinous and is difficult to split.
Is used in ship's blocks, and stern and outboard bearings. Tensile
strength along the fiber 14,800 lb. per square inch, crushing 7,000.
Weight per cubic foot 60 to 65 lb. Sp. gr. 1.14.
Locust has a peculiar striped grain, is hard, and is suitable for
exposed places where great durability is required. Weight per
cubic foot 46 lb. Sp. gr. .73.
Mahogany, hard, close grained, difficult to split, takes a fine
polish. The straight-grained varieties are little affected by the
weather,- although the cross varieties warp and twist. Used for
planking in high speed motor boats, deck houses, etc., and interior
finish. Weight per cubic foot 46 lb. Sp. gr. .73. The soft and
inferior grades from Honduras and Mexico are called baywood.
Maple, light colored, fine grained, strong and heavy, used for
interior trim. Weight per cubic foot 43 lb. Sp. gr. .68.
Oak (white), very durable, largely employed in wood vessels
for frames and beams, can be steamed and bent. Is not suit-
able for steel vessels as it contains an acid which attacks the steel. ,
Weight per cubic f6ot 46 lb. Sp. gr. .74.
Oak (live), the strongest of the oaks, seldom comes in long
straight pieces. Weight per cubic foot 59 lb. Sp. gr. .95.
Pine, long-leaf or Southern pine, hard and strong, extensively *
used for decks. Weight per cubic foot 44 lb. Sp. gr. .70.
Pine (Oregon) — same as Douglas fir. See above.
Pine (short-leaf), much resembling long-leaf, but inferior to it.
Suitable for interior finish, flooring, etc. Weight per cubic foot
38 lb. Sp. gr. .61. North Carolina pine is the trade name given,
to that species of short-leaf pine known as the loblolly.
Pine (white), light, very strong and easily worked. Weight
per cubic foot 26 lb. Sp. gr. .41.
Poplar or whitewood, light, brittle and warps if weather changes.
Is cheap and easy to work. Weight per cubic foot 30 lb. Sp. gr. .48.
Spruce, light, strong, tougher and more durable than white .
pine. Varieties: black, white and red. Norway spruce or white
deal has a tough, straight grain which makes it an excellent ma-
terial for masts. Spars, paddles and oars are often made of spruce.
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162 SHIPBUILDING MATERIALS
Black spruce is used for wharf piling. Weight per cubic foot 27
lb. Sp. gr. .4 to .46.
Teak, a heavy, strong wood suitable for railings, armor backing,
etc., does not readily split nor warp when exposed to alternate
moisture and dryness. Will stand heavy wear, and contains a
resinous oil which prevents the rusting of steel and iron when in
contact with it. Weight per cubic foot 52 lb. Sp. gr. .82.
Physical tests, see Strength of Materials.
Feet board measure, see page 9.
Shipping weights, see page 18.
MISCELLANEOUS NON-METALLIC MATERIALS
Oakum. — Consists of hemp fibers obtained from old rope. For
caulking decks with oakum a light one-handed mallet is employed,
the caulker hitting a thin flat chisel, forcing the oakum between
the planks. In heavy work, as in the outside planking as a final
operation, a large horsing mallet is used. After the deck seams
are caulked, the oakum being slightly below the surface of the
planks, they are payed, i. e., hot pitch is poured into the seams.
Oakum is put up in standard bales weighing 50 lb. gross.
Caulking Cotton. — For caulking yachts and motor boats where
the planking is thin, instead of oakum.
Portland Cement.^-When mixed with sand and water is laid as
a covering for the shell plating in the inner bottom. It not only
protects the plating against the corrosive action of foul bilge water
but against the erosive action of hard substances which may be
washed about. In oil tankers the cement may be omitted, but
vessels carrying sugar and copper ore should have a thick coat.
Portland cement is not readily affected by ordinary substances
but is softened by sulphate of ammonia. When laid, say 1J^ ins.
thick, the proportion should be 3 parts of sand to 1 of cement,
"but if less thickness is required the proportion may be as 2 to 1.
Pure Portland cement weighs about 120 lb. per cubic foot; if laid
with sand, 128 lb. See also Structural Details.
Insulating Materials. — These are magnesia, asbestos, cork and
hair felt — the two former for covering hot surfaces, as steam pipes
and boilers, and the two latter for cold pipes, as those containing
brine.
Magnesia is the best non-conducting material and is the most
expensive. In combination with asbestos as 85% magnesia and
15% asbestos it can be obtained in a variety of forms as in sec-
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ASBESTOS 163
tional pipe covering, blocks, sheets and cement. A bag of 85%
magnesia weighs 60 lb. and will cover approximately 40 sq. ft.
one inch thick.
Asbestos will soften when in contact with water and should
not be used where parts are subject to moisture as under the engine
room floor plates or on cold water pipes. It can be obtained in
sectional pipe covering, blocks, sheets and cement. A bag of
asbestos cement weighs 100 lb. and will cover about 40 sq. ft. one
inch thick.
Either cork or hair felt may be fitted around cold water and
brine pipes but should not be on steam. Cork may be obtained
in the granulated form or in sheets. Hair felt comes in rolls \i,
14, % 1 and 1 Yz ins. thick by 6 ft. wide, and after being put around
a pipe is covered with canvas. See Refrigeration.
Mineral Wool, a fibrous material made from blast furnace slag,
is a good non-combustible covering, but is brittle and liable to
fall to powder where much jarring exists.
Air space alone is one of the poorest non-conductors, though
the best owe their efficiency to the numerous minute air cells in
their structure. This is seen in the value of different forms of
carbon, from cork charcoal to anthracite dust, the former being
three times as valuable, though in chemical constitution they are
practically identical.
Based on one inch thickness, the approximate efficiencies of the
following coverings referred to bare pipes are — asbestocel, 76.8%,
magnesia, 83.5%, asbestos, Navy brand, 82%.
Steam Pipe Covering is made in standard lengths 3 ft. long,
which when placed around a pipe are fastened on by brass bands;
in addition canvas may be sewed around them. The best and most
expensive is magnesia, which has high non-conducting qualities
and is also very light. Next to this are asbestos sheets made
into pipe form so there are air cells, thus giving (as air is an excel-
lent non-conductor of heat) a cheap and efficient covering. For
high-pressure steam piping 85% magnesia is used, while for lower
pressure and exhaust piping asbestos with air cells, about one inch
thick, answers. Valves and fittings are covered with cement, and in
some instances the flanges have coverings that can be easily removed.
Boiler Covering. — For the best results on high temperatures
1J^- to 2-inch magnesia blocks are wired on, and finished with a
coat of magnesia cement. A cheaper covering for pressures over
125 lb. may consist of 2-inch asbestos blocks, covered with wire
mesh and finished with a 3^-inch coat of cement.
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164
SHIPBUILDING MATERIALS
Cylinders may be covered with asbestos or magnesia blocks
wired on and then inclosed* in teak or mahogany vertical strips
secured with brass bands. Sheet iron is sometimes put on instead
of wood strips.
Abstract of Specifications Issued by U. S. Navy Department
Part
Covering
Lagging
Main cylinders and valve* chests.
•
Upper cylinder heads
Magnesia
Magnesia
Magnesia
Magnesia
2}^ ins.
Lagged all over with
galvanized sheet iron
Neatly fitted iron floor
Steam and exhaust pipes, valves,
fittings and flanges, separators,
feed water heaters
Boiler drums
plates, with flat top-
ped corrugations
t
Canvas sewed on and
painted
Magnesia for lagging, and in uptakes, smoke pipes, etc., will be
composed as follows:
Carbonate of magnesia 85%
Asbestos fiber 15%
Canvas on pipes 2 ins. dia. and smaller 8 oz. per yard
Canvas on pipes above 2 ins. dia., separators, etc. 15 oz. per yard
Tests of Insulating Materials
Transmission
Transmission
in B.t.u. per
in B.t.u. per
Square Feet
Thick-
Square Feet
per Degrees F.
Material
ness
per Degrees F.
Difference in
Inches
Difference in
Temperature
per One Inch
Temperature
per 24 Hours
Thickness
per 24 Hours
Composition cork board (granu-
lated cork and asphalt)
2
4.5
9
Slag wool in board form, some-
times called rock cork
2
3.8
7.6
Nonpareil cork board
1
6.2
6 2
Nonpareil cork board
2
3.
6
Nonpareil cork board
3
2.2
6 6
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NON-CONDUCTING MATERIALS
165
Percentage of Heat Transmitted Through Various Pipe
Coverings
(The heat loss from an uncovered pipe is taken as 100%)
Substance
Heat Low
Per Cent.
Pipe without covering
Pipe painted with black asphaltum
Pipe painted with light drab lead paint
Pipe painted glossy white
Asbestos paper, two layers one inch hair felt canvas covered
Asbestos paper, 4 thicknesses
Asbestos paper, 2 thicknesses.
Asbestos, molded, mixed with plaster of Paris.'
Asbestos and wool felt
Magnesia, molded, applied in plastic form
Magnesia as a class
Mineral wool as a class
Rock wool as a class
Fossil meal as a class ,
100
105
107
95
15
50
75
30
20
25
20
20
22
25
From Plumbers' Handbook, Int. Text Book Co.
Table of Relative Value of Non-Conducting Materials
Substance
Value
Loose wool
Geese feathers
Felt, hair, or wool
Carded cotton
Mineral wool
Carbonate of magnesia
Rice chaff, loose
Paper
Cork
Sawdust
Wood ashes
Wood across grain
Coal ashes
Asbestos, paper
Asbestos, fibrous
Air space undivided. . .
Sand
3.35
1.08
1.00
1.00
.68 to .83
.67 to .76
.76
.74
.71
.68
.61
.40 to .55
.35 to .49
.47
.36
.14 to .22
.17
.50 to
.61 to
From Handbook, Lukens Iron & Steel Co.
Digiti
zed by G00gk
SECTION IV
SHIP CALCULATIONS
Length over all is* the length measured from the foremost tip of
the stem bar to the aftermost tip of the overhang of the stern.
Length between Perpendiculars. — For vessels with straight
vertical stems, the length between perpendiculars is taken from the
fore side of the stem bar to the aft side of the stern post. When
the stem is raked, that is, inclined forward, the length is measured
from the fore side of the stem bar at the upper deck. Should the
vessel have a clipper or curved stem, the length is measured from
the point where the line of the upper deck beams would intersect
the fore edge of the stem if it were produced in the same direction
as the part below the cutwater.
Lloyd's Length is measured from the fore part of the stem to the
after part of the stern post on the range of the upper deck beams
except in awning or shelter-deck vessels, in which cases the length
is measured on the range of the deck beams next below the awning
or shelter deck. In vessels in which the stem forms a cutwater the
length is measured from the point where the upper-deck beam line
would intersect the fore edge of the stem if it were produced in the
same direction as the part below the cutwater. In vessels having
cruiser sterns, the length is taken as 96% of the extreme length
from the fore part of the stem on the range of the upper-deck
beams to the aftermost part of the cruiser stern, but it is not to be
less than the length from the fore part of the stem to the after
side of sternpost when fitted, or to the fore side of the rudder stock
when a sternpost is not fitted.
Length for Tonnage. — See Registry.
Extreme breadth is measured over the outside plating at the
greatest breadth of the vessel.
Breadth molded is taken over the frames at the greatest breadth.
166
Digitized by V3 vJ(JV LV^
DEPTH OF HOLD
167
jrfw/r/fff or S/t*/jherhecA or 3r/afoe2>ec£<
3
Figure 18
Depth, Lloyd's (molded) (Fig. 18) is measured at the middle of
, the length from the top of keel to the top of beam at the side of the
uppermost continuous deck, except in awning or shelter-deck
vessels, where it may be taken to the deck next below the awning
or shelter deck, provided the height of 'tween-decks does not exceed
8 ft. When the height of 'tween-decks exceeds 8 ft. the depth is to
be measured from top of keel to a point 8 ft. below the awning or
shelter deck.
Depth of Hold is measured from top of ceiling at the middle of
the length in vessels with ordinary floors or from top of ceiling on
double bottoms if ceiling is laid, or when no ceiling is laid from the
tank top plating to the top of the beams of the first deck. Two
and a half inches is the usual allowance for the ceiling.
Draft — Most vessels have their draft load line parallel to the
keel so that the draft at any point is the same, but in vessels with
a drop or drag keel the draft is taken from the lowest point of the
drag. The actual or extreme draft includes the depth of the keel.
Figures which are placed at the bow and stern for indicating draft
read to the lowest point of the figure and are 6 ins. high; so if the
ile
168
y
SHIP CALCULATIONS
water was half way up on 10, the draft would be 10 ft. 3 ins. or if
just covering it, 10 ft. 6 ins.
Extreme Proportions. — A vessel is said to have extreme propor-
tions when her length exceeds eleven times her molded depth. In
such a vessel additional longitudinal strength is required.
Displacement is the amount of water displaced by a vessel. If
she is floating in equilibrium in still water, the weight of water she
displaces equals the weight of the vessel herself with everything on
board. The displacement in cubic feet when floating in salt water
divided by 35, and when floating in fresh water divided by 36,
gives the total weight of a ship and her cargo in tons; as 35 cu. ft.
of salt water weighs 1 ton (2240 lb.) and 36 cu. ft. of fresh water
the same amount.
The displacement of a steel vessel is calculated to the molded
lines, and, as a rule, no allowance is made for the thickness of the
7b/ts soo
Figure 19.— Curves of Displacement and Dead Weight*
Digitized by VJiOOQLC
CURVE OF DISPLACEMENT 169
shell plating, although the excess of water displaced by the shell
amounts to about 1% of the total. For wooden vessels (motor
boats, tugs, lighters, etc.) the displacement is calculated to the
outside of the planking. On the Great Lakes (United States) the
displacement is calculated in tons of 2000 lb., elsewhere in tons of
22401b.
Displacement = dead weight X 1.64 (approximately).
For calculation of displacement see "Displacement Sheet."
A curve of displacement (see Fig. 19) can be plotted as follows:
Lay off on the line OL to any convenient scale the draft in feet of
the vessel, as 1, 2, 3, etc., and draw in the water lines. On the
load-water line lay off to any convenient scale divisions representing
tons, the distance WL representing the displacement at the load-
water line, WL' the displacement at the second water line, and so
on. A curve drawn through the points W, W't etc., to O is the
curve of displacement. From this curve, knowing the draft, any
displacement can be readily obtained.
Dead weight is the carrying capacity and includes the tons of
cargo and generally the coal. The dead weight equals about 64%
of the displacement.
The registry of a vessel as prescribed by the U. S. Treasury
Department, Revised Statutes, Section 4150, is as follows:
The registry of every vessel shall express her length and breadth, together with
her depth and the height under the third or spar deck, which shall be ascertained
in the following manner: The tonnage deck in vessels having three or more
decks shall be the second deck from below; in all other cases the upper deck is the
tonnage deck. The length from the fore part of the outer planking on the side of
the stem to the after part of the main stern-post of screw steamers and to the
after part of the rudder-post of all other vessels measured on the top of the tonnage
deck shall be accounted the vessel's length. The breadth of the broadest part on
the outside of the vessel shall be accounted the vessel's breadth of beam. A
measure from the under side of the tonnage-deck plank, amidships, to the ceiling
of the hold (average thickness) shall be accounted the depth of the hold. If the
vessel has a third deck, then the height from the top of the tonnage deck plank to
the under side of the upper-deck plank shall be accounted as the height under the
spar deck. All measurements to be taken in feet and fractions of feet, and all
fractions of feet shall be expressed in decimals.
Register ton measurement is the measurement based on a ton of
2240 lb. occupying 100 cu. ft.
Gross tonnage is the measurement in register tons of the interior
capacity of the entire ship.
Net tonnage is the tonnage in register tons upon which payment
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170 SHIP CALCULATIONS
is made, and is the «pace available for cargo and passengers.
Roughly, for freight steamers, if the net tonnage is multiplied by
2.5, the tons of cargo that can be carried are obtained. This
assumes that the cargo occupies 40 cu. ft. per ton. For calculation
of tonnage for vessels using the Suez Canal, see " Suez Canal
Tonnage Rules," published by Board of Trade, London; and for
those using the Panama Canal see " Panama Canal Rules,"
published by the Treasury Department, Washington.
Cubic Capacity. — When the term " cubic capacity cargo space "
is used, this is taken as the cubic capacity of the cargo holds cal-
culated to the molded lines of the vessel. Cubic grain measure-
ment is sometimes taken one or two inches inside the molded lines.
Cubic bale measurement is generally understood as being to the
bottom of the deck beams and to the inboard face of the reverse
frames.
Tons per Inch of Immersion. — It is often necessary to find the
distance a vessel will sink when known weights are placed on board,
or how much she will rise if weights are removed.
If A is the area of a water plane in square feet, then the displace-
ment of a layer 1 ft. thick, supposing the vessel to be parallel sided,
is A X 1 = A cu. ft., or ^r tons in salt water. For a layer \ in.
oO
thick, the displacement is „, 19 tons, and this is the number of
tons that must be placed on board to make a vessel sink 1 in., or
the number of tons to be removed to lighten her 1 in.
Examples. — (1) A steamer 350 ft. long, 45 ft. beam, has a draft of 20 ft. How
many tons must be placed on board to make her sink 1 in.?
First find the area of the water plane, assuming a coefficient of fineness of the
water plane as .85. Then the area is
.85 X 350 X 45 = 13,387.5 sq. ft.
_ . , . . . area of water plane 13,387.5 0< _ .
Tons per inch of immersion = * = — j^n — = 31-8 tons-
Therefore, when the steamer is drawing 20 ft., 31.8 tons would have to be placed
aboard to make her sink 1 in.
(2) At a draft of 16 ft., the tons per inch of immersion of a steamer are 12.5. If
75 tons of cargo were removed, find the decrease in draft and the new draft. '
Decrease in draft = ■-%-? = 6 ins.
u.o
New draft = 16 fl*6 ins. = 15 ft. 6 ins.
A curve of tons per inch of Immersion (see Fig. 20) can be
plotted as follows: Lay off on the line OL to any convenient scale
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TONS PER INCH OF IMMERSION
171
the draft in feet of the vessel, as 1, 2, 3, etc. (in a large vessel take
water lines say 4 ft. apart), and draw in the water lines. On the
water lines lay off to any convenient scale divisions representing tons,
that must be added to make the vessel sink 1 in. A curve through
the points is the curve of tons per inch of immersion.
fO // fz /3 Tons
Figurj 20.— Curve of Tons per Inch of Immersion.
Approximate Formulae for Tons per Inch of Immersion. — Let
L = length of water line in ft.;
B = beam in ft.
For fine vessels, tons per inch of immersion
For medium vessels, tons per inch of immersion
For cargo vessels, tons per inch of immersion
LXB
600
LXB
550
LXB
500
The coefficient of fineness of water plane is the ratio of the area,
of the water plane to the circumscribing rectangle. For ships with
fine ends this is 0.7; for ships of ordinary form, 0.75; for ships with
bluff ends, 0.8 to 0.89.
Prismatic coefficient is the ratio between the volume of the dis-
placement and a solid having a transverse area equal to the area of
the immersed midship section multiplied by the length taken for
calculating the displacement.
Digitized by LiOOQ LC
f
Y72 # SHIP CALCULATIONS
The coefficient of fineness of midship section is the ratio of the
area of the immersed midship section to the area of its circumscribing
rectangle. The coefficient for ordinary ships varies from .85 to .95,
the latter value being for a section with a very flat bottom.
The block coefficient is the ratio of the volume of the displace-
ment to the volume of a block having the same length, breadth and
mean draft. Below are the block coefficients of various types of
vessels:
Barges 85 to .9
Very full cargo vessels up to 8 knots .8 to .85
Full cargo vessels up to 12 knots 76 to .82
Large cargo vessels up to 12 to 14 knots 7 to . 76
Intermediate cargo and coastwise vessels 65 to . 7
Fast Atlantic liners 6 to . 65
English Channel passenger steamers 5 to. 6
Steam trawlers, tugs 56 to ^6
Paddle passenger steamers 46 to .57
Battleships 6 to . 65
Cruisers 48 to .55
Torpedo boats and destroyers 4 to .48
Sailing vessels 6 to .72
Steam yachts 45 to .6
Sailing yachts 3 to .52
Above coefficients from Design and Cons, of Ships, J. H. Biles.
Wetted Surface is the area of the immersed portion of a vessel.
Let W = displacement in tons; L — length of vessel in ft.;
D — mean draft in ft.; V =» volume of displacement in cu. ft.
V
Wetted surface in sq. ft.-1.7LXD + j;
or - 15.5 VW X L,
or - (LxBXl.7) + (LXBXblockcoefficient);
or
^F«(a.4+2^=)
Center of Buoyancy is the center of gravity of the displaced
water and is determined solely by the shape of the under water
portion of a ship's hull. For calculations see " Displacement Sheet."
In vessels of ordinary form the vertical position of the center of
buoyancy below the foad-water line varies from .4 to .45 of the
mean draft to the ttrp of the keel, the latter (.45) being the value
in. vessels of full form. For yachts and vessels of unusual shape
the above approximate rule does not apply.
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TRANSVERSE METACENTER
173
Morrish's approximate formula for the distance of the center of
buoyancy below the load-water line is as follows:
Let V = volume of displacement up to the load-water line in
cu. f t. ; A =» area of load-water plane in sq. ft. ; d — mean draft to
top of keel in ft.
Then the center of buoyancy below the load-water line =■
\32 ^ Af
To find the fore and aft position of the center of buoyancy of a
vessel, having given the areas of equidistant cross sections. Lay
off a table as below which is of a vessel with cross sections 9.5 feet
apart, the position of the center of buoyancy being desired from
the middle station, that is, No. 5.
Station
Area
of
Section
Simpson's
Multi-
pliers
Functions
of
Area
Number of
Intervals
from Middle
Station
Moments
1
1.2
17.6
41.6
90.7
134.3
115.4
61.7
30.4
6.6
1
4
2
4
2
4
2
4
1
1.2
70.4
83.2
362.8
268.6
661.6
123.4
121.6
6.6
4
3
2
1
0
1
2
3
4
4.8
2
211.2
3
166.4
4
362.8
5
745.2
6
661.6
7
246.8
8
364.8
9
26.4
1699.4
1299.6
Excess of products aft =
Volume of displacement cubic feet =
Then center of buoyancy aft of middle
station or ordinate 5 =
1299.6-745.2 = 554.4
M X 9.5 ft. X 1699.4
HX9.5X 9.5 X 554.4
MX9.5X 1699.4
« 3.9 ft.
Transverse Metacenter. — Assume that a vessel is floating in still
water under normal conditions (see Fig. 21), W L being the water
line, B the center of buoyancy, and<G the common center of gravity
of the hull, engines, boilers and all other weights on the vessel.
Digitized by VJiOOQLC
174
SHIP CALCULATIONS
,FIgTn*81
If the vessel is inclined at a small angle, then W U is the
new water line, and the new volume of displacement has its
center of buoyancy at B'. The upward force of buoyancy acts
through B\ while the weight of the ship acts vertically down through
G, the center of gravity. The vertical line through B' cuts the center
line of the vessel at M , and this point M is called the meta-
center and the distance G M the transverse metacentric height.
Table of Metacentric Heights
Type of Ship
Value of 0. M.
Harbor vessels, as tugs
15 to 18 ins.
Small cruisers
2 ft. to 2 ft. 6 ins.
Battleships
4 ft. to 5 ft.
Shallow draft gunboats for river use
Merchant steamers
12 ft.
1 ft. to 3 ft.
Sailing vessels %
3 ft. to 3 ft. 6 ins.
See also table on Merchant Vessels and table in paragraph To Find Vertical
Position of the Center of Gravity.
Digitized by VjiOOQIC
HEIGHT OF METACENTER 175
A ship with a large transverse metacentric height comes to the
upright position very suddenly, while a ship with a small one comes
to the upright position more slowly and is more comfortable in a
seaway.
Referring to the figure it will be noted that the weight of a vessel
acting vertically downward through the center of gravity, and the
buoyancy of the water acting vertically upward through the new
center of buoyancy form a couple. Draw G Z perpendicular to
B' M. Then G Z is the arm of the couple, and the moment ot
the couple is W X G Z.
If G is below M the ship is in stable equilibrium.
If G is above M the ship is in unstable equilibrium.
If G coincides with M the ship is in neutral or indifferent equi-
librium.
For small angles up to 10° to 15°, M practically remains in a
constant position, hence G Z — G M X sin 8. As G Z is the arm
of the couple, then the moment of the couple is W X G M X sin 8, *- \{ jL y
and if M is above G, this moment tends to right the ship, and is
called the moment of statical stability at the angle 8.
The above is called the metacentric method of determining a '
vessel's stability, and can only be used for small angles up to 15°.
For larger angles cross curves of stability are calculated. (See
section on Cross Curves.)
. Example. A vessel 250 ft. long having a displacement of 3300 tons has a meta-
centric height of 2 ft. 6 ins. What is her righting moment if she is inclined at an
angle of 12 degrees?
Righting moment = W XO M X Bin 0
- 3300 X 2.5 X sin 12° = 1715 ft.-tons.
To Find Height of Metacenter Above the Base Line. — The follow-
ing formula* gives the height with a fair degree of accuracy.
Let H = draft in feet ,
B = beam in feet
a = a coefficient varying between .57 and .54, depending on
the coefficient of fineness and exact shape of lines, and decreasing
for the same vessel about .01 as the draft increases from 12 ft.
to 24 ft. The values .57 to .54 are for coastwise passenger and
freight steamers of modern design, having a fine load water line
forward and full midship section.
* From International Marine Engineering, New York.
Digiti
zed by G00gk
176
SHIP CALCULATIONS
C = coefficient of .078 to .082 for coastwise passenger and
freight steamers.
Then the height of the metacenter above the base = a X H -\-
CX B*
H '
To Find the Moment of Inertia of a Water Plane About the Center
Line. — Divide the length of the plane into a convenient number of
parts and arrange a table as follows:
Number
of
Ordinate
Semi-
ordinates of
Water Planes
Cubes of
Semi-
ordinates
Simpson's
Multipliers
Functions
of
Cubes
1
2
3
• 4
etc.
1
4
2
4
etc.
The sum of the functions of cubes X H the common distance the
ordinates are apart X H X 2 (as only semi-ordinates were taken)
= the moment of inertia of the water plane about its center line.
Approximate Formula for the Moment of Inertia of a Ship's Water
Plane About the Center Line.
Let L = length in feet
B = beam in feet
n = coefficient for ships with fine water-line planes .04
coefficient for ships with moderate water-line planes .05
coefficient for ships with very full water-line planes .06
J = moment of inertia
Then / = n L B*
Formula for Finding the Distance of the Transverse Metacenter
above the Center of Buoyancy.
/ = moment of inertia of water plane about its center line
V = volume of displacement in cubic feet
Then B M = y.
See Displacement Sheet.
Digiti
zed by G00gk
DISPLACEMENT SHEET 177
Approximate Formula for the Distance of the Transverse Meta-
center above the Center of Buoyancy.
The formula for the transverse metacenter is B M = -y
Let B — beam in feet
D — molded draft in feet
a =#a coefficient of .08 to .1 (say .09 for a vessel with
a block coefficient of .75)
B2
Then B M - a X -^
Displacement Sheet. — The procedure outlined below is the one
usually employed in calculating the displacement, centers of buoy-
ancy and metacenters.
On a profile of a vessel drawn to a convenient scale, say H in. =
1 ft. for small, and \i in. = 1 ft. for large, divide the distance be-
tween the forward and after perpendiculars into any number of
even parts. At these divisions erect perpendiculars, take cross
sections, lay out a body plan and on it draw water lines. In the
displacement calculations made for the tug on page 180, 10 sections
or ordinates were taken with half-ordinates at both ends, the ordi-
nates being 9.5 ft. apart. The water lines were spaced 2 ft. apart,
with a one-foot water line between the base line and second water
line. Half-ordinates and an additional water line were taken so
the calculations would be close.
Rule a sheet as shown on page 180 and write in a horizontal
row the figures 1, 2, 4, etc., for the water lines and below Simpson's
multipliers as H, 2, 1% 4, etc. In the vertical column at the left
write the numbers of the ordinates as 1, 1J^, 2, etc., and in the next
column Simpson's multipliers as J^, 2, 1J^, 4, etc. From the body
plan scale the distances from the center line to the intersection at
the second water line and write it down (generally in red ink)
under 2 water line as .10; do this for the 1J^ ordinate which is .33,
and so on for alt the water lines.
Multiply the Simpson's multipliers below the water lines by
the half-breadths and write the products below. Thus .10 X 1J^
= .15, .33 X lj^ = .50, etc. Add these products horizontally for
each ordinate as for No. 1, .15 + .4 + .2 -f .4 -f .1 = 1.25 and
write the sum in the column functions of areas. Multiply the func-
tions of areas by Simpson's multipliers as J^, 2, 1J^, 4, etc., writing
the products in the column multiples of areas. Add up this column
Digitized by VJiOOQ 1C
178
SHIP CALCULATIONS
which in the present case is 3256 and multiply it by }4 of each in-
terval and by }4 of the distance the water lines are apart, thus, }£
X 2 ft. X H X 9.5 ft. X 2 (as half-breadths were taken), which will
give the volume of the displacement in cubic feet as 13748, and
to convert it into salt water tons divide by 35, as 35 cu. ft. of salt
water weigh one ton.
To find the fore and aft center of buoyancy, multiply the multiples
of areas by their lever arm from the midship ordinate, thus giving
forward and after moments as .60 X 5 = 3., 35.22 X4H = 158.49,
etc. Add up the forward moments and the after ones. In the pres-
ent case the after sum or 3287.92 is the largest, so subtract the
forward from it leaving a remainder of 617.95. Multiply 617.95
by 9.5 ft., the distance the ordinates are apart, and the product
divided by the sum of the multiples of areas will give the location
of the center of buoyancy; in the present vessel it is aft of No. 6,
the midship ordinate, a distance of 1.83 ft.
t- To find the vertical position of the center of buoyancy, multiply
the half-breadth as for 2 W. L. at No. 1, viz.: .10 by Simpson's
multiplier J^ giving .50; do the same for the next half-breadth,
as .33 by 2, giving .66, writing the products in the column to the
right and so on. Continue thus for the other water lines, and add
up each as 2.75, 133.33, 170.90, etc., multiplying them by Simp-
son's multipliers as }4, 2, 1%, 4, etc., the products being 1.37,
246.66, 256.35, etc. Take moments about the base line which is 0
with arms H, 1, 2, 3, etc., the sum of which is 9416.47. Multiply
9416.47 by the distance the water lines are apart or 2 ft., and divide
by the sum of the multiples of areas, the quotient being 5.78 ft.,
which is the distance the center of buoyancy is above the base line.
The'above calculations may be simplified by using a planimeter
for getting the areas of the cross sections. Thus for the displace-
ment lay off a table as below:
Station
Reading of
Planimeter
Simpson's
Multipliers
Functions of
Areas
1
2
etc.
2
etc.
Then instrument scale constant X sum of functions of areas
X M common interval X 2 (if only half-areas of sections were
Digitized by VjiOOQ 1C
CENTER OF BUOYANCY
179
taken) = volume of displacement in cubic feet, which divided by
35 will give the displacement in salt water tons.
To find the fore and aft center of buoyancy use a table as follows:
Station
Planimeter
Reading
Simpson's
Multipliers
Functions
of Areas
Arms
Functions
of Moments
Sum of
Functions
Forward
Aft
difference between sum of functions of moments X interval
= distance
sum of functions of areas
center of buoyancy is from the station the moments were taken
about. If the after moments are the greatest then the center of
buoyancy will be aft of the station taken, and if less then forward
of it.
* To find the vertical center of buoyancy lay off a table thus:
Water
Plane
Reading of
Planimeter
Simpson's
Multipliers
Functions
of Areas
Arms Above
Base Line
Functions of
Moments
1
2
etc.
sum of functions of moments X distance water planes are apart
sum of functions of areas
distance center of buoyancy is above the base line.
For the metacenters lay off a table as on page 181. To find the
transverse metacenter multiply the cubes of the ordinates or half-
breadths by tSimpson's multipliers as lA, 2, 1J^, 4, etc, writing
the products in the column of functions of cubes. Take the sum
of this column which is 34488.92 and multiply it by % of the dis-
tance the ordinates are apart, which in the present case is 9.5 ft.
also by }4 and by 2 (if half-breadths were taken) giving a product
of 69359.21, which is the moment of inertia J of the water plane
about its fore and aft center line. The distance between the trans-
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182 SHIP CALCULATIONS
verse center of buoyancy and transverse metacenter B M is given
by the formula B M = -~?> / being the moment of inertia of the
water plane as just found and V the volume of the displacement in
cubic feet. Thus BM = i = 69fQ5,9;Q21 = 5.04 ft.
V Io74o
To find the longitudinal metacenter multiply the functions of
ordinates by the arms or levers there are from the midship ordinate,
writing the product in the column Functions for Center of Gravity
of Water Plane. Add up the forward and after functions, and as
the after in the present vessel is the largest, subtract the forward
from it, giving a remainder of 105.82. Multiply 105.82 by the
distance the ordinates are apart, viz.: 9.5 ft., and divide the
product by the sum of the functions of ordinates 289.12, the quo-
tient being the distance the center of gravity of the water plane is
aft of No. 6 ordinate.
Multiply the functions for the center of gravity of the water
plane by the arms 5, 4J^> 4, etc., writing the products in the column
of functions for moment of inertia, the sum of the products being
1758.32.
As the longitudinal metacenter is to be referred to the center
of gravity of the load water plane, a correction is necessary to the
sum of the functions for moment of inertia, viz., 1758.32.
Let / = moment of inertia about the middle ordinate
y = distance the center of gravity is from the middle ordi-
nate
A — sum of the functions of ordinates X H distance ordi-
nates are apart
Then the new moment of inertia I0 around the center of gravity of
the water plane is given by the expression I0= I — Ay*
By referring to page' 181 the various calculations are shown,
giving a value of I0 as 982923. Hence if B M is the distance be-
tween the longitudinal center of buoyancy and the longitudinal
metacenter, I0 the moment of inertia as just found and V the vol-
ume of the displacement in cubic feet, then B M = -^ and sub-
982923
stituting in this formula the values previously found \ojaq ^en
the quotient is 64.2 ft., which is the longitudinal metacentric
height.
Digitized by LjOOQ IC
CURVES OF STABILITY 183
Curves of Stability.* — These are obtained by calculating and then
plotting the length of the righting arm or lever at different angles
of inclination of the vessel and drawing a curve through the points
found. For these calculations there must be known: (1) the posi-
tion of the center of buoyancy in the upright position; (2) the
position of the center of gravity of the vessel; (3) the volume of
the displacement; and (4) the value of the moment of transference
of the immersed and emerged wedges parallel to the new water line.
The resulting curves (see Fig. 22) are important and are often
given to the captain so he will know the condition of his vessel
under various loadings. (See Loading of Cargoes.) The minimum
value of the distance between the center of gravity and metacenter*
(G M) in steamers of medium size is about one foot when loaded
with a homogeneous cargo that brings them to the load water line.
For small cargo vessels the distance between the center of gravity
and the metacenter should not be less than 9 ins. provided a right-
ing arm of like amount is obtained at 30° to 40°. For sailing
vessels a higher value of G M is required, the minimum being 3 ft.
to 3 ft. 6 ins. with a homogeneous cargo.
Referring to Fig. 22, the righting levers are given vertically
and the angles of inclination of the ship given horizontally in de-
grees. The important features in the curves are: the inclination
of the curve to the base line at its origin, the angle at which the
maximum inclination occurs, and the length of the righting lever
at this angle.
Increasing the beam of a vessel increases the initial stability
but does not greatly influence the area inclosed by the curve of sta-
bility or its range.
Increasing the freeboard has no effect on the initial stability
(supposing the increase of freeboard does not affect the position
of the center of gravity), but it has a most important effect in
lengthening out the curve and increasing its area.
In the table in Fig. 22 various conditions of loading a steamer
391 ft. 6 ins. long, 51 ft. 6 ins. beam, and 29 ft. 3 ins. deep are given.
(1) In Curve A, the ship is light, water in boilers, but no cargo,
bunker coal, stores or fresh water on board, and all ballast tanks
empty.
(2) B same as (1), but with bunker coal, stores and fresh water
on board.
(3) C ready for sea, water in boilers, bunker coal, stores and
fresh water aboard, and the holds and 'tween-decks filled with a
♦From Ship Cons, and Calculations, G. Nicol. OOS
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184
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CROSS CURVES OF STABILITY
185
homogeneous cargo of such a density as to bring the steamer to her
summer load line.
(4) D same as (3), with bunker coal, stores and fresh water
consumed, approximating to the end of the voyage.
(5) E ready for sea, water in boilers, bunker coal, stores and
fresh water aboard, and all ballast tanks filled.
(6) F same as (5), but with bunker coal, stores and fresh water
consumed.
(7) G same as (3), but loaded with a coal cargo, part of the
'tween-decks empty.
(8) H same as (7), but with bunker coal, stores and fresh water
consumed.
Cross Curves of Stability.* — These are calculated for two or three
conditions as, when the vessel is light, loaded, and loaded with the
bunkers empty. Select angles of inclination as 15°, 30°, 50°, 70°
and 90°. Prepare body plans for the fore body (see Fig. 23) and
after body, and draw on them the load water line and the inclined
Make the calculation first for the loaded condition.
X
* From A class book on Naval Architecture, W. J. Lovet%igiti
186
SHIP CALCULATIONS
Find the area of each section of immersion and emersion at the
assumed inclination, by a planimeter preferably, altho these can be
found by Simpson's rules. Mark the center of gravity of each
section. Draw a line X X perpendicular to the inclined water
plane. This is the line about which the moments of the wedges
are taken. Prepare a table as follows for the submerged wedge.
Ordinates
Areas
Simpson's
Multipliers
Products
Levers
About X X
Moments
1
2
3
4
5
etc.
1
4
2
4
2
etc.
s
M
M
Distance of center of gravity of wedge from X X = -5-
o
Also find volume of wedge by multiplying S by J| common
interval. Repeat this calculation for the emerged wedge. Lay out
a table thus:
Volume
Levers About X X
Moments
Submerged wedge ....
Emerged wedge
St
M
Digiti
zed by G00gk
TO FIND THE AREA
187
Si is the difference between the volumes of the submerged and
emerged wedges. Make a correction for the difference, laying out
a table thus:
s
Leverage
Moments
a
a
m
§
o
©
a
3
I
I
i
•43
r
a
a3
5
j
I
©
S
1
I
i
1
1
©
a
1
1
2
4
3
2
etc.
etc.
5
+ s
1?
•
-E
S)-
0
The leverage is half the difference of the two ordinates.
Total moment M ± Si X G
Total volume of displacement
= BR
zed by G00gk
188
SHIP CALCULATIONS
In Si X G note if the greater volume is on the emerged side and
the center of gravity of it on the emerged side, then the moment
obtained has to be deducted from the total moment. If the greater
volume is on the submerged side and its center of gravity on the
submerged side the moment has to be added to the total moment.
GZ - B R—B G sin 6
BR
BM
sin 0
Proceed to find B R in the same manner for SO0, 50°, 70° and 90°.
Also find B R for other drafts for all the angles of inclination.
When this is done the cross curves of stability may be constructed,
by setting up at the different drafts the G Z found for the different
inclinations. Run lines through each series of spots and these lines
are the cross curves of stability. See Fig. 25.
To construct stability curves (Fig. 26) lay off the inclinations
15°, 30°, etc., horizontally and vertically the values of GZ as
previously found. Draw curves through the points thus laid off.
The cross curves show constant inclination at varying displace-
ments. The stability curves show constant displacement at vary-
ing inclinations. The cross curves show the value of the righting
arm G Z. A curve of righting moments could also be made show-
ing the foot-tons (the value of W [displacement] X G Z). In
preparing the body plan the sections are drawn to the uppermost
continuous deck. If a watertight poop, bridge or forecastle become
immersed at the higher angles of inclination, the value of their
buoyancy should be calculated.
As the above curves have been considered with the vessel station-
ary, they are called static curves.
NOTES ON STABILITY
189
Notes on Stability. — For ordinary vessels the transverse meta-
center remains practically unchanged up to 10° inclination. The
value of G M should not be less than 10 ins. and have a righting
arm of at least 10 ins. at 45°.
An ordinary seagoing ship should have a range of stability of
70°. Stability varies as the square of the breadth and inversely
as the draft. A 300-foot steamer when loaded had a maximum
righting lever of 8 ins., while a similar one under similar conditions
but 2 ft. broader had a maximum righting lever of 12 ins. Free-
board is an important factor in stability, as the stability imme-
diately begins to decrease when the edge of the deck gets under
water, so , that every additional inch of freeboard increases the
vessel's range.
Approximate Formula for Calculating Stability (G Z).
Let 0 = angle the vessel is inclined, that is, the angle between
normal water line and the inclined
G M = distance between the center of gravity and the
metacenter
B M = distance the metacenter is above the center of
buoyancy,
righting arm
GZ -
Then
GZ -
G M sin 0 + ^ tan 20 sin 6
Up to an angle of 30°, provided the ratio of the beam to the draft
is not abnormally great, the above formulae may be used instead
of the long stability calculations. The values at inclinations of
Digitized by VJiOOQLC
190
SHIP CALCULATIONS
10°, 15° and 20° are practically the same as obtained with the
usual stability calculations.
Trim is the difference between the forward and aft draft of a vessel.
Thus, suppose a vessel draws 12 ft. forward and 15 ft. aft; then she
is said to trim 3 ft. by the stern.
Longitudinal Metacenter. — Let B (see Fig. 27) be the center of
buoyancy when floating on an even keel, W L, and suppose the trim
of the vessel to change, the displacement being the same, then Bi
is the new center of buoyancy. Draw B\M a vertical line meeting
B M at M . Then M is the longitudinal metacenter, and the dis-
tance G M the longitudinal metacentric height.
Figure 27
Moment to Alter Trim One Inch. — Suppose a weight w is moved
from w to w, then the change of trim = W Wi + LL\ = (Wi S +
S Li) X tan 0 — length of load water line X tan 0.
The movement of the weight w causes the center of gravity of
the vessel to move aft a distance Gi G. Let W = the displacement
in tons, a = the distance the weight w is moved, then
(?iG = (?MXtanH W £a and tan 6 -
change of trim
W
w X a
WXGM
length of load water line
Change of trim in feet = length of load water line (L) X tan $ =
L X w X a
WXGM
Digiti
zed by G00gk
CALCULATIONS FOR TRIM 191
To get the moment to alter trim one inch substitute in w r ,=
change of trim ., , t . , , w X a A
length of load line IT X G M L
Therefore the moment to alter trim one inch = w Xa — T-j —
WXGM
LX12
foot-tons.
Example. A 350-ft. steamer, displacement 6700 tons at her designed draft, has
a longitudinal metacentric height of 350 ft. If 10 tons of cargo in her forward
hold was moved 100 ft. aft, find the change in trim.
W X Q M 6700 X 350
Moment to change trim one inch = = ■ * = 55.8 foot-tons.
Li X 1« OOU X 1^
Moment aft from shifting cargo — 10 tons X 100 ft. = 1000 foot-tons.
Hence change of trim aft = ' -- 0 ■ = 17.9 ina
55.8
Approximate Calculations for Trim. — In the formula, moment
W X G M
to alter trim one inch = T foot-tons, if G M is assumed
Li X 1^
to be equal to L the length of the ship, which is roughly true in
the case of ordinary cargo vessels at their load displacements, the
W
trimming moment per inch becomes y^ foot-tons.
Another approximate formula giving closer results than the
above is the following:
T = tons per inch of immersion
A = area of load water plane in square feet
L = length on the load water line in feet
B = breadth of ship amidships in feet
V = volume of displacement in cubic feet
W = displacement in tons
The height of the longitudinal metacenter above the center of
A2 X L
buoyancy in ordinary cargo steamers is B M = .0735 fi
™ *j- si %, i xxr vol. of displacement V
assuming B M = G M , and as W = ~ = rr
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192 SHIP CALCULATIONS
WXGM
LX 12
Then the moment to alter trim one inch
V x 07o5 A'XL
35 BxF A* 30.9 X T2
t — +ty — .000175 -g- foot-tons, or « foot-tons.
Another formula for the moment to alter trim one inch is
length on water line X displacement
n X draft
where n for fine vessels = 190
where n for ordinary = 180
where n for cargo = 172
To Estimate the Displacement of a Vessel when Floating Out of
Her Designed Trim.
T — tons per inch of immersion
y = center of flotation aft of amidships in feet .
L ~ length of vessel in feet
Then the extra displacement for one foot of extra trim =
Example. A steamer 350 ft. long, draws 17 ft. forward and 24 ft. 3 ins. aft, thus
trimming 7 ft. 3 ins. by the stern. When loaded she trims 5 ft. by the stern. If
the center of flotation is 14 ft. aft amidships, and the tons per inch of immersion 35,
what is the steamer's displacement?
At a draft of 20 ft. 1 H ins. I ' « — ' ' I ner displacement from the
displacement curve is 5850 tons.
12 X 35 X 14
The displacement for one foot of extra trim = 5^ =" 16.8 tons, and
for 2 ft. 3 ins. extra trim = 37.8 tons.
Thus new displacement = 5850 + 37.8 » 5887.8 tons.
To Find the Distance the Longitudinal Metacenter is Above the
Center of Buoyancy.
Let V = volume of displacement in cubic feet
I0 = moment of inertia of water plane about a transverse
axis passing through the center of flotation.
Then the longitudinal metacentric height B M — ^. See Meta-
centers, page 186.
To Find the Trim Corresponding to any Mean Draft and Longitud-
inal Position of the Center of Gravity by Trim Lines or Curves.*—
See. Fig. 28. Draw a line W L to represent the mean draft for
* From Ship Calculations and Cons., G. Nicol.
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CALCULATIONS FOR TRIM
193
which the trim line is required. On this line a point B is taken
as the longitudinal position of the center of buoyancy at a level
keel, and a line N N is drawn representing the midship line of the
vessel. Thus the distance B N represents the distance the center
of buoyancy is from amidships, which in the present case is forward
of it.
The horizontal distance from B of the center of buoyancy of the
vessel trimming 2 ft. by the stern is calculated as follows:
Change of trim = length of water line X tan 0 (for 0 see Fig. 27)
a — change of trim
~~ length of water line
Now G Gi equals nearly B Bi, or the distance between the cen-
ters of buoyancy before and after the trim has been changed, so
G Gi = B Bx = G M X tan 0.
G M is approximately equal to the length of the ship L on the
change of trim
L
, w change of trim , 2 ft.
L X ^ = LX~T
water line, then substituting G M = L and tan 0
G Gi = B Bx = G M X tan $
and in the present case this distance is set off from B.
Next calculate the position of the center of buoyancy with the
vessel trimming 4 ft. by the stern, the same method as just out-
lined being used, and lay off this distance as B B2.
At Bi and B2 verticals are erected, and the corresponding trims
(2 ft. and 4 ft.) laid off, the same scale being used. Through the
points thus found and the point B a line is drawn, which is the trim
line required.
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194 SHIP CALCULATIONS
For forward trims the trim line should be continued below its
level line to indicate the movement of the center of buoyancy in
that direction. It should be noted that the center of gravity and
center of buoyancy are here assumed to travel the same distance
when a change of trim takes place. This is not quite true as B is
below G and therefore more remote from M , and moves a greater
distance. For very accurate work the distance plotted from B
towards W should be the calculated travel of the center of gravity
plus B G X tan 0. It is not necessary to proceed to this refinement
in ordinary cases, as the error involved is not worth considering.
From the trim line just drawn can be determined any trim
up to 4 ft. (other trims, as 6 ft., 8 ft., etc., could be plotted if de-
sired), due to the movement of weights on board. For if the dis-
tance the center of gravity travels aft on account of the movement
of the weights be ascertained and plotted from B along the level line
C, and a vertical line be erected to intercept the trim line at Z), C D
must be the trim by the stern, as the center of buoyancy and center
of gravity are always in the same vertical line.
A trim line is only reliable at its own draft, and when the change
of displacement is considerable a new curve is required. For
ordinary purposes three conditions are sufficient, viz., load, ballast,
and light.
Effect of Flooding 'a Damaged Compartment. — To find the effect
of a compartment being thrown open to the sea by collision or other
accident, account must be taken not only of the water that would
enter if the ship remained in her original position, but also of the
additional water which will enter due to the heel, change of trim,
and sinkage caused by such flooding.
When the compartment is wholly under water, and the water
is prevented from spreading by a watertight deck or inner bottom
the effect is the same as of adding a weight in a known position.
To Find the Trim when a Compartment is Flooded. — The weight
of the water in the compartment up to the original water line should!
be found and the parallel sinkage determined assuming the com-
partment open to the sea and the admitted water placed with its
center of gravity in the vertical plane containing the center of
gravity of the added layer of displacement. This distance measured
in the trim diagram above the height of the original water plane,
will give the point from which the level line and corresponding trim
fine should be drawn. The trim can then be obtained (as described
in the paragraph on Trim Lines) by finding the travel aft of the
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CALCULATIONS FOR TRIM
i
195
center of gravity, assuming the weight to be translated to its true
position.
It will next be necessary to calculate the weight of water in the
compartment, assuming the surface to rise to the level of the new
draft, and to use it in the same way in another trim estimate. If this
should differ much from the first calculation, it may be necessary
to proceed to a third.
Or instead of the above, which is the trim line method, first de-
termine the amount of mean sinkage due to the loss of buoyancy,
and second, determine the change of trim caused.
Quantity of Water That Will Flow into a Ship Through a Hole
in Her Side.
Let H = distance center of the hole is below the water line in feet
A = area of hole in square feet
g = acceleration due to gravity (32.16)
V — rate of flow in feet per second
Then V = V2 g H - S\/H approximately
The volumejn cubic feet of water passing through the hole per sec-
ond = 8 VH X A
Example. A hole having an area of 2 sq. ft., 4 ft. below the water line was made
in the side of a ship. What would be the approximate tons of water that would
flow into her per minute?
Cubic feet per second = 8 \/H X A - 8 \/l X 2 - 32.
Cubic feet per minute - 32 X 60 = 1920.
1920
Tons per minute = "35""
54.85 tons.
Calculating the Trim by the Trim Line Method when a Compart-
ment is Flooded.* — Assume a box-shaped vessel 210 ft. long, 30 ft.
beam, and 20 ft. deep, drawing 10 ft. forward and aft. Suppose
she is in collision and a compartment at the after end is flooded
Find the draft. (See Fig. 29.)
B
►
c
W
'Sz
S<
A
Figure 29
* From Ship Calculations and Cons., G. Nicol.
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196 SHIP CALCULATIONS
Using the trim line method, first obtain the trim line at 10 ft.
draft. W L is the level water line, W2L2 and W^LA those when
at 2 ft. and 4 ft. by the stern.
Assuming the vessel to be floating in salt water, her displacement
210 X 30 X 10
is — = 1800 tons, and in passing from the W L to
W%Liy the wedge of displacement LSI* moves to the position
W S Wt. As S L is half the vessel's length, and L L2 one foot, the
volume of the wedge is = 1575 cu. ft., and in moving
aft its center of gravity travels a horizontal distance gx g2 or
105X2: + 105X2 _140ft.
The corresponding movement of the vessel's center of buoyancy
is from B to Bt) then BBt^GM XtanS
i^Xl40
. n wXa 35 A1W 1575
tan v = —
W X G M 1800 X 140 1800 X 35
anA » » 1575 X 140
aBdBBt'mi x35=s3-5ft-
That is the horizontal travel of the center of buoyancy with the
vessel trimming 2 ft. by the stern is 3.5 ft. With the vessel 4 ft. by
the stern, the horizontal travel is double 3.5 ft. or 7 ft.
From the above, a trim line can be drawn for the initial draft.
Trim lines corresponding to other displacements can be obtained
in the same manner. Fig. 30 is the complete diagram for the vessel
and shows cross curves with a range of from 7 ft. 6 ins. to 15 ft. draft.
Next begin with the calculation for the bilging.
10 X 10 X 30
Weight of water in bilged compartment = — = 85.71
uu
tons;
Parallel sinkage assuming water situated amidships and compart-
85.71 X35 X12 ..
ment open to sea = t^t ^ — = 6 ins.
Horizontal travel aft of vessel's center of gravity, assuming the
* Center of gravity of a wedge is H from the apex.
f The length of the water line, instead of being 210 ft., is now 200 ft., as the
compartment flooded is 10 ft. long.
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CALCULATIONS FOR TRIM
197
water at the increased draft to move into its true position and the
ship's bottom to be intact:
new draft of 10' 6" X 10' length X 30' beam ^ x
w = ^z — 90 tons
oo
__ 210' — 10' (length of compartment) inA .
a — gy sB 1UU It.
W = original displacement of 1800 tons + 90 tons = 1890 tons.
w
1890
Figure 30
Referring to Fig. 30 the trim line corresponding to a level line at
10 ft. 6 ins. can be drawn, and by measuring 4.76 ft. along this line
from A B, and erecting a perpendicular and scaling it, its length
2 ft. 10Ji ins. is the trim by the stern. The drafts will be
Forward = 10' 0' + parallel sinkage of 6' - y2 (2' 10M") =
'9' oy8"
Aft - 10' 0' + parallel sinkage of 6" + % (2' 10^") -
11' UK'
v In the second approximation, start with the vessel in the above
8
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198 SHIP CALCULATIONS
trim. The weight of the water in the bilged compartment will be
11.86 X 10 X 30
35
= 101.66 tons.
D „ , . ! 101.66 tons X 35 cu. ft. X 12 ins. a%, .
Parallel smkage = 210 ft. X 30 ft = ^ ins'
nearly.
Taking the center of gravity of the water line at. the middle of
the length of the compartment, then the travel of the vessel's center
wXa 101.66 X^
of gravity due to admission of water = w = 1800 . 101 66 =
5.35 ft. aft. By laying this off on the trim diagram, on the water
line, and scaling up to the trim line, the trim will be found to be
3 ft. 2J£ ins. by the stern.
Dividing this equally forward and aft, and adding 6% ins. as the
parallel sinkage, the drafts become
Forward 10' 0* + 6M' - 1' W% = 8' 11^"
Aft . 10' 0* + 6M" + 1' 7%" = 12' 2%*
Calculating. the Trim by Mean Sinkage when a Compartment is
Flooded.* — A rectangular lighter 100 ft. long, 40 ft. beam, 10 ft. deep,
floating in salt water at 3 ft. draft, has a collision bulkhead 6 ft.
from the forward end. If the compartment forward of this bulk-
head is flooded, what would be the trim in the damaged position?
(See Fig. 31.);
(1) Determine the amount of mean sinkage due to the loss of
buoyancy.
(2) Determine the change of trim caused.
(1) The lighter, due to the damage, loses an amount of buoyancy
represented by the shaded part G B, and if it is assumed the lighter
sinks down parallel, she will settle down at a water line w I such that
volume wG = volume G B. This will determine the distance x
between w I and W L. (?L = 6 ft., w H = 94 ft.
For the volume w G = w H X 40 f t. X x
For the volume G B = G L X 40 ft. X 3 ft.
G L X 40 X 3 18,. 01/.
a; = -^tfxl0- = 94ftor2^mS-
(2) Change of trim.
* From Theo. Naval Architecture, L. T. Attwood.
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WHEN COMPARTMENT IS FLOODED
199
Volume of displacement in cubic feet = 100 X 40 X 3
100X40X3 2400
35 7
Displacement
= 342 tons, and this
weight acts through G, the center of gravity, which is 50 ft. from
either end.
UL-
A
£ 1
W
A
L
V
ef
<9
a
////
Figure 31
But there has been lost the buoyancy due to the part forward of
the bulkhead E F, and the center of buoyancy has now shifted back
to B1 such that the distance of Bl from the after end is 47 ft.
Therefore W, the weight of the lighter, acts down through G1
and W the upward force of buoyancy acting through B\ forming a
240ft ' 720ft
couple of W X 3 ft. = =y^ X 3 = -~ = 1028 foot-tons, tending
to trim the lighter.
To find the amount of this trim, the moment to change trim one
inch must be found by the formula.
Now G M equals B M nearly, therefore the moment to change
trim one inch =
342
XBM = ^XBM.
100 X 12 ~ 7
Let / = the moment of inertia of the intact water plane about
a transverse axis through its center of gravity.
V = volume of displacement in cubic feet = 12000
'-i^94
BM = ^ =
Moment to alter trim one inch =
nearly.
X 40) X 94*
40 X 94s
12 X 12000
2 X 40 X 94*
7 X 12 X 12000
= 66 foot-tons
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200
SHIP CALCULATIONS
7200
Therefore change of trim =» -^- — -^-
do oo
The new water line W1 & will pass through the center of gravity
of the water line wl at K, and the change of trim aft and forward
must be in the ratio 47:53,
47
100
53
Decrease of draft aft
15J^ ins.
X 15^ - 7M ins.
Increase of draft forward «
100
X 15J^ - SH ins.
New draft aft « 3 ft. + 2H ins. [from (1)] - 7% ins. = 2 ft. 7 ins.
New draft forward = 3 ft. + 2\i ins. [from (1)] + 8M ins. =
3 ft. 10H ins.
CENTER OF GRAVITY.
Coincident with the calculations of the displacement and cen-
ters of buoyancy, are made calculations of the fore and aft, and ver-
tical positions of the common center of gravity of the hull, ma-
chinery and cargo. The fore and aft position of the center of
gravity of all the weights must come over the fore and aft position
of the center of buoyancy. If on the first estimate it does not,
then the weights must be shifted until it does.
On a profile of the vessel draw a vertical line midway between
the forward and aft perpendiculars. Also draw a base line
parallel to the water line, for getting the vertical distance of the
center of gravity. Except when the keel is given a drag, the base
line is taken as the molded line of the frames at the keel.
To find the fore and aft position of the center of gravity of the
hull, lay off a table as follows:
Items
Weights
Dist. Cent, of Grav.
from Amidships
Moments
Aft
Forward
Aft
Forward
Shell plating
Bulkheads
Deck plating
&c.
w
M aft
M forward
y Google
CENTER OF GRAVITY
201
Assuming the moments aft to be greater than those forward then
moments aft — moments forward ,. , . - .. . -A
1~ n — distance center of gravity is aft
of amidships.
To find vertical position of center of gravity of the hull, lay off a
table thus:
Items
Weight
Dist. Cent,
of Grav.
from Base
Moment
Shell plating
Rillkhparjs ,
Deck plating
Web frames
&c.
•
w
M
The sum of the moments divided by the sum of the weights gives
the distance the center of gravity is above the base.
To find fore and aft position of the center of gravity of a ship,
rule a table as below:
Items
Weights
Dist. Cent, of Grav.
from Amidships
Moments
Aft
f orward
Aft
Forward
Hull
Boilers
Engines
Cargo in forward hold. . .
Cargo in aft hold
Stores forward
Stores aft
Rankers
Water ballast forward. . .
Water ballast aft
Fresh water
&c.
W
M aft
Mfor'd
y Google
202
-SHIP CALCULATIONS
Assuming the moments aft to be greater than those forward then
moments aft — moments forward ,. A '
~p- = distarice of center of gravity
aft of midships.
To find vertical position of the center of gravity of a ship, lay off
the following table:
Item
Weight
Dist. Cent, of
Grav. Above
Base
Moment
Hull
"
Boilers
Engines . .
Cargo in forward hold
Cargo in aft hold
&c.
w
M
The sum of the moments M divided by the sum of the weights
W will give the distance the center of gravity is above the base.
Care must be exercised in locating the engines, boilers, cargo,
tanks and other weights in a ship. If they are placed too high,
the ship will be unstable and if too low she will be very uncom-
fortable in a seaway, owing to too quick a return to the vertical
position.
The table below gives the heights of the center of gravity of
ordinary passenger and freight steamers, and of freight steamers.
Center of Gravity Above Base
Length
Breadth
Depth
Molded
Metacenter
Above Base
Machinery
Equipped Vessel
150'
30'
15'
10' 6'
IV 6*
25' 0*
200'
35'
20'
11' 0"
14' 6'
23' 0'
250'
40'
22'
12' 0'
15' 0*
18' 0'
300'
45'
24'
12' 6'
17' 6'
19' 0'
350'
48'
28'
13' 0*
19' 6'
20' 6'
400'
50'
32'
16' 0*
22' 0*
22' 0'
450'
54'
36'
18' 0'
23' 0'
23' 0'
Approximately the vertical height of the center of gravity of a
ship is .50 to .70 of the molded depth.
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Digitiz
EFFECT OF MOVING WEIGHTS 203
Effect of moving weights on the center of gravity of a vessel.
(1) Suppose the Weight Was Raised. — The distance the center
of gravity of the vessel was raised would be found by multiplying
the weight moved by the distance it was moved and dividing the
result by the total weight or displacement.
Example. A weight of 30 tons was raised from the hold and placed on the deck
of a steamer at a distance of 20 ft. from its original position. The steamer had a
displacement of 1000 tons. Find the distance the center of gravity was raised.
weight X distance _ 30 X 20 _
displacement = 1000 "" 6 ft*
(2) The Weight Was Removed. — In this case multiply the weight
by its distance from the center of gravity of the ship, and divide
the product by the displacement after the weight was removed.
Example. A weight of 30 tons 10 ft. below the center of gravity of a ship of
1000 tons displacement was removed. How much was the center of gravity raised?
weight X distance 30 X 10
displacement — weight 1000 — 30
.3 ft.
(3) Adding a Weight. — Multiply the new weight by its distance
from the center of gravity of the vessel and divide by the new
displacement.
Example. A weight of 30 tons was placed on board of a steamer with an original
displacement of 1000 tons 10 ft. below her center of gravity. Find the distance
the center of gravity was lowered.
weight X distance _ 30 X 10 _ 300 _
displacement + weight ~ 1000 + 30 ~ 1030 "" -28ft'
(4) Moving a Weight Athwartships. — Multiply the weight by
the distance moved and divide by the displacement.
Example. A weight of 20 tons at the center of the upper deck was moved 10 ft.
to starboard. The steamer had a displacement of 1000 tons. Find the distance
her center of gravity was moved.
weight X distance 20 X 10 ,
displacement = ""lOOCr = '2 ft' to larboard.
(5) Afoving a Weight in Two Directions. — The new positions
of the center of gravity can be found by using formulae (2) and (4).
Example. In a vessel of 4000 tons displacement, 100 tons of coal were shifted
so its center of gravity moved 18 ft. transversely and 4 ft. 6 ins. vertically. Find
the new position of the center of gravity.
100X4.5
By (2) the center of gravity will move vertically ^qqq — = . 11 ft.
100 X 18
By (4) the center of gravity will move horizontally — —£- — = 45 ft
4000
(Author not known)
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204 SHIP CALCULATIONS
In this case, however, the angle of heel is usually calculated instead of the dis-
tance the center of gravity moves. Thus in the above example assuming the
20 X 10 20 X 10
steamer had a Q M of 2 ft. the angle of heel would be «
1000 X G M 1000 X 2
= .10, consulting the table of natural sines, the angle is found to be 5 degs. 75 mins.
To Find the Center of Gravity of a Vessel by Moving Weights.* —
Even if the position of the transverse metacenter is known, it is
of itself of no value in predicting a vessel's initial stability as the
center of gravity of the entire vessel (hull, machinery, and cargo)
must be known. The center of gravity can be calculated as out-
lined above, or it can be obtained by the inclining experiment as
described below.
A perfectly calm day should be selected, all the crew ordered
off the vessel, all movable weights made fast, and the vessel trimmed
so she is perfectly upright. A plumb line is hung down one of the
hatches (sometimes two at two different hatches), usually as near
amidships as possible. At the end of the plumb line a horizontal
batten is placed on which can be marked the deviation of the plumb
line when the vessel is inclined.
A weight 1 is shifted from port to starboard on the top of weight
3, through a distance of d feet, and the deviation of the plumb line
noted.
Weight 2 is shifted from port to starboard on top of weight 4
and the deviation of the plumb line noted.
The weights 1 and 2 are then replaced in their original position,
the vessel returning to the upright position again.
Weight 3 is moved from starboard to port on top of 1 and the
deviation of the plumb line noted, and similarly 4 is moved on top
of 2. Then the weights are returned to their original position.
If to = weight moved in tons
W — displacement of vessel in tons
a = deviation of plumb line along the batten in ins.
I = length of plumb line in ins. •
d «- distance weight is moved in ft.
GM = distance between the center of gravity and the trans-
verse metacenter in ft.
wXdwXdXl
Then G M
TTxf WXa
* From Theo. Naval Architecture, E. L. Attwood.
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FREEBOARD
205
Example. A steamer has a displacement of 5372 tons, and draws 16 ft. 0 ins.
forward and 22 ft. 10 ins. aft. Weight used for inclining 50 tons, which was moved
36 ft. Length of plumb line 15 ft. Two plumb lines were used.
Deviation of Plumb line
in 15 ft.
Forward
(Inches)
Aft
(Inches)
5H
iom
10H
5H
10%
5H
10J4
Thus the mean deviation in 15 ft. for a shift of 25 tons through 36 ft. is 10 A
ins. - 10.312 ins.
w X d X I 25 X 36 X 15 X 12 *
Then OM — w x q - 53?2 x 1Q ^
1 Multiply by 12 to reduce to ins. as the deviations are in ins.
■ 2.92 ft.
FREEBOARD *
The full scantling vessel is taken as of sufficient strength, and is the
standard by which strength is gaged. Vessels which are less strong
are required to have more freeboard. For the full scantling vessel
the freeboard is determined solely by the desirable reserve of buoy-
ancy.
The percentage of the total volume which is given on Plate I
as a reserve buoyancy for a vessel of given type and dimensions
will be the amount of volume that must be left out of the water.
If a line be drawn upon this displacement curve at a draft sufficient
to cut off the given percentage of total volume, the height of side
above this draft will be the freeboard required.
In order to simplify and reduce the work that would be involved
by the above mode of determining the maximum allowable draft
and the consequent freeboard that corresponds to a given percentage
of reserve buoyancy, tables were evolved which, for a ship that con-
formed to a so-called "standard" ship, gave directly the percentages
of reserve of buoyancy and freeboards necessary for different sizes
and types of vessel. The curves of Plates 2 and 3 are plotted from
these tables.
The standard ship was considered to be a flush deck ship
with a certain sheer which was termed standard or normal sheer,
with a certain proportion of length to depth and with a standard
* Published in Int. Marine Engineering by Prof. H. A. Everett, revised by him.
April, 1917.
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206 SHIP CALCULATIONS
roundup of deck beams, and for this vessel the curves read directly.
Deck erections contribute to safety and are taken account of as a
corrective term, as are also other variations from the standard ship.
In practice the freeboard is actually assigned after the ship is built
and usually by one of the classification societies' agents, but its pre-
liminary determination is an important and necessary item in the
design of any vessel, as the draft plus the freeboard gives the depth.
The complete tables as issued by the British Board of Trade
take up a variety of modifications and corrections which are in-
volved by vessels differing from the arbitrarily assumed standard.
The following work is based upon the rules directly, although the
presentation and the wording are modified. The curves given on
Plates 1-4 are a graphical representation of corresponding tables
in the rules. Spar deck steamers and sailing vessels are not in-
cluded as these classes are not numerous in present-day designs.
The limitations of loading as laid down by the above act (for
complete text see publication issued by Marine Department of the
British Board of Trade, entitled Instructions to Surveyors, Load
Line) are represented by a disk and number of horizontal lines
which are cut and painted on the side of the ship amidships as
shown in Fig. 32. The upper edge of each line is the point of meas-
urement.
The word "freeboard," legally, denotes the height of the side
of the ship above the water line, measured at the middle of her
length along the load water line. It is measured from the top of
the deck at the side. The reserve of buoyancy necessary for flush
deck steamers of full scantling and awning deckers are given by
the curves on Plate 1 and these curves hold for any and every vessel
regardless of proportions. For the standard vessel of these classes
and within the dimensions given the freeboards required may be
read directly from Plates 2 and 3.
For awning deck vessels the freeboards are determined more
by considerations of structural strength than by reserve of buoy-
ancy, and indicate the dej)th of loading beyond which it is probable
that first class vessels of this type would be unduly stressed when at
sea. Therefore the freeboards and percentages of reserve buoyancy
are in excess of what would be required for full scantling vessels.
They are measured to the deck below the shelter or awning deck.
The freeboards given in the curves are for flush deck vessels in all
cases, and for the standard ship — a ship which has no deck erections,
has a proportion of length to depth of 12, has a roundup of deck
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207
Digiti
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208 SHIP CALCULATIONS
beams of \i inch per foot of beam, and has a mean sheer in accord-
ance with that derived from the curves shown on Plate 4.
The data required for determining the freeboard by the curves
are:
1. Type of ship
2. Dimensions
3. Mean sheer
4. Round of beam
5. Description of deck (where statutory deck line is placed)
6. Coefficient of fineness
The type of ship must be agreed upon in order to ascertain which
table will meet the case and whether modifications are necessary.
The length for freeboard is measured at the load line from the
fore side of the stem to the after side of the sternpost in sailing
ships, and the after post in steamers.
The breadth for freeboard is the extreme breadth measured to
the outside of plank or plating as given on the certificate of the
ship's registry.
The depth for freeboard is the depth of hold as given on the cer-
tificate of the ship's registry. This is the depth for determining
the coefficient of fineness. (Upper deck beam at side in flush deck
vessels, main deck beam at side in spar and awning deck vessels
to top of ceiling or sheathing on double bottom.)
Coefficient of Fineness. — This in one-, two-, and three-deck
vessels is found by dividing 100 times the gross registered tonnage
of the vessel below the upper deck by the product of the length,
breadth, and depth of hold. In shelter deck vessels the registered
depth and tonnage are taken to the deck below the shelter deck.
Molded Depth. — The molded depth of an iron or steel vessel,
as used in the curves, is the perpendicular depth taken from the
top of the upper deck beam at side, at the middle of the length of
the vessel to the top of the keel and the bottom of the frame at the
middle line. This is the depth for the proportion of length to depth.
Freeboard.' — The molded depth, taken as above described, is
that used in the curves for ascertaining the amount of reserve
buoyancy and corresponding freeboard in vessels having a wood
deck, and the freeboard is measured from the top of the wood deck
at side, at the middle of the length of the vessel. Where wood
decks are not fitted on the upper decks, the freeboard should be re-
duced by the thickness of the wood deck or the percentage of it
Digitized by vjOOQ 1C
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210 SHIP CALCULATIONS
corresponding to the percentage of the length covered by substantial
deck erections if they cover less than 70%.
The following example will illustrate the application oj the curves
when dealing with a standard vessel. Jn a steamer 357 ft. long,
extreme beam 40 ft., depth of hold 26 ft., registered tonnage under
deck 2,980 tons, molded depth 29.8 ft., under deck capacity 298,000
cu. ft., which divide by 382,000 — that is, the product of the length,
breadth, and depth of hold — the quotient is .78 or the coefficient
of fineness.
Referring to Plate 2 at 29.75 ft. molded depth and coefficient
.78, the winter freeboard given for a standard steam vessel (with-
out erections and length 12 times the molded depth) is 7 ft. 7 ins.,
which corresponds to a reserve buoyancy of 32% of the total bulk.
Vessels rarely conform to the proportions assumed for the stand-
ard, and the correct determination of freeboard for the actual
vessel becomes a matter of properly applying the corrections to
allow for the departure from the standard. The variations most
commonly met with are the sheer, deck erection, and proportions
of length to depth. The corrections for each of these items must be
made and in the order given, as the correction for erections is based
upon the difference between the freeboard for full scantling vessels
corrected for sheer and the freeboard for awning deck vessels (un-
corrected).
Sheer. — The tables are framed for vessels having a mean sheer
of deck measured at the side, as shown in the sheer diagram of Plate 4.
In flush dock vessels and in vessels with erections on deck,
when the sheer of deck is greater or less than the above, and is of
gradual character, divide the difference in inches between it and
the mean sheer provided for by 4, and the result in inches is the
amount by which the freeboard amidships should be diminished or
increased, according as the sheer is greater or less.
In all cases the rise in sheer forward and aft is measured with
reference to the deck at the middle of the length, and where the
lowest point of the sheer is abaft the middle of the length, one-half
of the difference between the sheer amidships and the lowest point
should be added to the freeboard specified in the tables for flush
deck vessels and for vessels having short poops and forecastles only.
Erections on Deck. — For steam vessels with topgallant fore-
castles having long poops, or raised quarter decks connected with
bridge' houses, covering in the engine and boiler openings, the
latter being entered from the top and having an efficiently con-
Digitized by vjiOOQ 1C
211
Digiti
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212
SHIP CALCULATIONS
structed iron bulkhead at the fore end, a deduction may be made
from the freeboard given in the curves according to Curve A, Plate 4.
When the erections on a vessel consist of a topgallant forecastle,
a short poop having an#efficient bulkhead and bridge house discon-
nected, the latter in steamers covering the engine and boiler open-
ings, and being efficiently inclosed with an iron bulkhead at each
end, a deduction may be made from the freeboard given in the
curves, according to Curve B, Plate 4.
When the erections consist of a topgallant forecastle and bridge
house only, the latter in steamers covering the engine and boiler
openings, and being efficiently inclosed with an iron bulkhead at
each end, a deduction may be made from the freeboard given in
the curves according to Curve C, Plate 4.
When the erections on a steamer consist of a short poop or raised
quarter deck of a height from 3 ft. to 6 ft. for lengths of ship of 250 ft.
to 400 ft., and topgallant forecastle only, the former being inclosed
at the fore end with an efficient bulkhead, and when the engine and
boiler openings are entirely covered, a deduction may be made
from the freeboard given in the curves according to Curve D,
Plate 4.
Vessels of Extreme Proportions. — For vessels whose length is
greater or less than 12 times the molded depth for which the curves
are framed, the freeboard should be increased or diminished as speci-
fied in the following table:
Table 1
Correction in freeboard. for a
Molded Depth
Length
Change of 10 ft.
in Length
Ft.
Ft.
1.2
20 -23
240-276
1.3
23^-25^
28S-306
1.4
26 -28
312-336
1.5
2S1A-30*A
342-366
1.6
31 -33
372-396
1.7
33^-50
402-600
For shelter deck vessels the correction is Y* that specified in the above table.
Thus if the vessel in the above example were 367 ft. long, the
winter freeboard would be 7 ft. 7 ins. plus 1.5 ins., or 7 ft. 8.5 ins.
For steam vessels with normal inclosed deck erections as on Plate 4
jvJ^v^
ROUND OF BEAM 213
(Curves A and B), extending over A or more of the length of the
vessel, the correction for length should be % that specified in the
table.
Round of Beam. — In calculating the reserve of buoyancy an
allowance has been made for the roundup of % inch for every foot
of the length of the midship beam. When the total roundup of the
beam in flush decked vessels is greater or less than given by this rule,
divide the difference in inches by 2 and diminish or increase the free-
board by this amount. For vessels with erections on deck the
amount of the allowance should depend on the extent of the main
deck uncovered.
Breadth and Depth. — It has been assumed that the relation
between the breadth and depth is reasonable, and for vessels of less
relative breadth the freeboard should be increased to provide a suffi-
cient range of stability. The following illustrates the application
of the curves when dealing with a vessel not conforming to the
standard type:
A vessel 234 ft. long, 29 ft. beam has a molded depth of 17 ft.,
the coefficient of fineness being .72. Suppose she has a poop and
bridge house of a total length of 121 ft. and a forecastle of 20 ft.,
and the sheer forward measured at the side 4 ft. 6 ins., and aft
2 ft. 1 in.
Ft. Ins.
Freeboard by Plate 2, if of standard proportions, without
erections and with the normal amount of sheer 2 11
The mean sheer by rule is 33.4 ins., or 6 ins. less than that
in the vessel, and the reduction in freeboard is 6 ins. di-
vided by 4 \x/i
Freeboard of vessel without erections and with 39 J^ ins.
mean sheer 2 9M
Freeboard by Plate 3 as awning deck 93^
Difference 2 0
The combined length of the erections is \\\ or six-tenths of the
length of the vessel, and the allowance for erections from Curve A,
Plate 4, will be four-ten the of 24 ins. or 9}^ ins. Thus
Digitized by VJiOOQlC
214
SHIP CALCULATIONS
Deduct Ins.
Amount deducted from freeboard for excess of sheer 1J^
Amount deducted from freeboard for erections 9 A
Amount deducted if vessel be fitted with an uncovered
iron main deck = A X ZlA 2
The length being 30 ft. in excess of that for which the
tables are framed, the addition to the freeboard for
excess length is A of \% or 1.1 ins. or
13
1H
That is \\XA ins. is to be deducted from 2 ft. 11 ins. leaving a win-
ter freeboard of 1 ft. \\XA ins. Corresponding summer freeboard
1 ft. 9 ins.
Vessels loaded in fresh water may have less freeboard than that
given in the several tables, according to the following scale:
Table 2
Reduction in Freeboard
Molded Depth in Ft.
Vessels Without
Erections on Deck
Shelter and Awning
Deck Vessels
19 and under 22
4
5
6
4^
22 and under 25
5
25 and under 28
5M
28 and under 31
6
31 and under 34
VA
The weight of a cubic foot of salt water is taken in the above table as 64 lb. and
of fresh water 62.5 lb.
In no case shall the deepest load line in salt water, whether in-
dicating the summer or Indian summer line, be assigned at a higher
position than the intersection of the top of the upper deck with the
vessel's side at the lowest part of the deck. In the case of shelter
deck vessels the deck next below the shelter deck is to be regarded
as the upper deck.
So far the question of freeboard determination has been con-
sidered from the viewpoint of its determination for some existing
ship whose characteristics are known. The most useful function
of the work as presented here is to permit a solution for the depth
of vessel under design. The accurate determination of freeboard
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216 SHIP CALCULATIONS
should properly be attempted only from the complete tables re-
ferred to earlier, but from the information here presented, it is pos-
sible readily to determine the freeboard and therefore depth for a
proposed design which has progressed sufficiently to have its length,
draft, block coefficient, and general arrangement selected. In gen-
eral the coefficient of fineness is sufficiently close to the block co-
efficient to accept the latter for entering the curves.
In considering a vessel under design, the general procedure
for determining the freeboard of a full scantling vessel should be
as follows:
1. Assume a molded depth which seems reasonable, enter the
curves, and for this depth read off the freeboard for the proper co-
efficient of fineness.
2. Correct this freeboard for sheer and erections and add the
corrected freeboard to the draft to determine a revised molded
depth. Multiply it by 12 and the difference between this and the
actual length gives the basis for determining the corrections for
proportions.
3. Determine the correction for proportions and the original
freeboard corrected for these three elements (sheer, erections, and
proportions), when added to the draft, should give a molded depth
in agreement with that originally assumed. If it does not, repeat
the solution, starting with a modified assumed depth. The first
trial will rarely give agreement but the second or third should
suffice.
Shelter deck steamers now form such a large proportion
of the tonnage afloat that they need to be treated as a special class,
and the revised rules do so take cognizance of them. The freeboard
of a shelter deck steamer must in no case be less than the freeboard
which would be assigned to a complete awning deck steamer of the
same dimensions. The shelter deck rules are framed for a vessel
having a complete superstructure covering the full length of the
vessel, the deck continuous and unbroken at the side, but having
one or more openings along the middle line of the deck, such open-
ings not to have permanent means of closing in the shape of hatch-
ways fitted with coamings, cleats, etc. The deck below the shelter
deck is called the upper deck and is the one to which freeboard is
measured.
For shelter deck vessels the steps for determination of freeboard
are the same as in full scantling vessels, considering them as full
scantling vessels with very long erections, and the freeboard is
Digitized by UOOQ LC
ASSIGNING FREEBOARDS 217
measured to the deck below the shelter deck (upper deck). There
is no correction for round up of deck beams for awning and shelter
deck vessels. The order of procedure is:
1. Assume a reasonable depth (molded) and read the freeboard
from the curve for this abscissa on Plate 2.
2. Correct this for sheer and use this corrected freeboard in esti-
mating allowances for erections.
3. Correct for erections.
4. Use this newly corrected freeboard for determining the depth
(molded) for proportions. Multiply it by 12 and correct for pro-
portions.
5. Add this final freeboard to the draft and get a depth which
should agree with that first assumed. If it does not, repeat the
solution. Two or three trials should suffice.
In assigning freeboards to shelter deck vessels, the following
rules should be observed:
1. In making the sheer correction in accordance with the para-
graph on Sheer, the sheer is to be measured at the ends of the vessel
and the freeboard corrected for sheer is to be used in estimating
the allowance for erections.
2. (a) If there is but one opening in the shelter deck the allow-
ance for deck erections is to be determined from Curve A, Plate 4,
provided that the effective length of the shelter deck is not less than
six-tenths of the length of the vessel.
(b) If there are two or more openings in the shelter deck the
allowance for deck erections is to be determined from Curve B,
Plate 4, provided that the effective length of the shelter deck, ex-
cluding openings, is not less than six- tenths of the length of the
vessel.
3. The effective length of the shelter deck is to be calculated in
the following manner, provided the openings in the shelter deck do
not exceed half the vessel's breadth at the middle of the length of
the opening. The length is taken as if each opening were an open
well. The value of each part is assessed in accordance with the
different regulations affecting poops, bridge houses, and forecastles,
open or close^. The final allowance for erections will depend upon
whether or not temporary but efficient means are provided for
closing the openings in the shelter deck.
(a) If efficient means as specified below are provided for tem-
porarily closing the openings in the shelter deck, the effective length
of the shelter deck is to be reckoned as the length computed as
Digitized by VjiOOQ 1C
218 SHIP CALCULATIONS
prescribed above, plus half the difference between that length and
the length of the vessel.
(b) If efficient means for temporarily closing the openings are
not provided, the effective length of the erections is to be computed
by adding to the length computed as above, one-fourth, instead of
one-half the difference between that length and the length of the
vessel.
(c) If the openings in the shelter deck are wider than the half-
beam at that point, the addition to the assumed length of erec-
tions is to be modified in proportion to the relation which the actual
opening holds to the specified breadth and to a complete well.
To illustrate the method of determining the depth for a new
design, and also the application of the rules to the shelter deck type
of vessel, note the following: A complete shelter deck vessel 490 ft.
long, 58 ft. beam, 28 ft. draft, block coefficient .80, has one tonnage
opening in the shelter deck. Assume for the first trial depth
r^ or -T5- = 40 ft., approximately
Ft. '
At 40 ft. depth and .80 coefficient of fineness the freeboard
for a full scantling vessel is 11 ft. 8 ins. (Plate 2) 11 . 67
The sheer forward is 9 ft. and aft 3 ft., so the mean sheer is
9-1-3
«T X 12 = 72 ins. The standard or normal mean sheer
2i
from Plate 4 is 60 ins., so that the excess sheer is 72 — 60 =
12
12 ins., and the sheer correction is -r — 3 ins. = .25 ft 25
.4
This is to be subtracted, as the sheer is greater than the nor-
mal, then freeboard corrected for sheer is 11 .42
Freeboard for awning deck (Plate 3) (uncorrected) 8.41
Difference 3.01
The correction for erections is 90% of this (Curve A, Plate 4),
as the erections cover 95% of the vessel length, .9 X 3.01 = 2.71.
The freeboard corrected for sheer and erections then becomes
11.42 - 2.71 = 8.71 ft. This, with a draft of 28 ft., gives a molded
depth of 8.71 + 28 = 36.71 ft.
A standard ship of this depth would have a length 12 times as
great or 36.71 X 12 « 440 ft. (approximately), which is 50 ft.
shorter than the actual ship, so the freeboard must be increased
Digitized by VJiOOQ 1C
FREEBOARD OF SCANTLING VESSEL 216
1 7
to correct for proportions. From Table 1 this correction = -57-
inch for every 10 ft. excess of length, and the correction in feet is
¥xBxS=o708x§ = -35ft-
Therefore the freeboard corrected for sheer, erections and propor-
tion becomes 8.71 + .35 = 9.06 ft., and the molded depth is 9.06 +
28 = 37.06 ft.
This depth does not agree with that first assumed, so a second
solution will be made using the depth just found as a trial depth.
Assume for the second solution a trial depth of 37 ft. •
Freeboard of full scantling vessel 10 . 50
Less sheer correction .25
10.25
Freeboard for awning deck vessel 7 . 25
Difference * 2.99
Correction for erections .9 X 2.99 2.69
Freeboard corrected for sheer and erections 7 .56
Draft '. 28.
Depth of ship at 28 ft. draft 35.56
Corresponding length of standard ship 427.
Length of actual ship 490.
Difference 63.
Correction for proportions (.0708 X 63) 43
Final corrected freeboard 7.56 + .43 7.99
Depth at 28 ft. draft = 28 + 7.09 35.99
Repeating this process for a third trial depth of 35 ft., a re-
sulting depth of 35.31 ft. and freeboard of 7.31 ft. is obtained.
Table 3
Allowable reduction from winter freeboard for summer free-
board. Double these reductions allowed for the Indian Summer line
and 2 ins. more required for the Winter North Atlantic line if of 330
ft. length or less.
Digiti
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220
SHIP CALCULATIONS
Molded Depth
Reduction
Molded Depth
Reduction
Ft.
Ins.
Ft.
' Ins.
16.5 to 19
2
34 to 35.5
6
19 " 22
*A
36 " 37.5
VA
22.5 " 24.5
3
38 " 39.5
7
25 " 26.5
% *A
40 " 41.5
m
27 " 28.5
4
42 " 43.5
8
29 " 30
*A
44 " 45.5
SH
30.5 " 32
5
46 " 47.5
9
32.5 " 33.5
VA
48 " 50
9>i
Miscellaneous Notes
In the United States there are no standard requirements although
the American Bureau of Shipping has made suggestions as to the
loading as follows: "No vessel is to be loaded so that the freeboard
(measured at the lowest point of sheer) from the main deck .
stringer plate to the water edge shall be less than is indicated in
the following table:
Depth of Hold from Top of Ceiling to Under
Side of Main Deck Beam
Freeboard at Lowest Point
of Sheer for Each Foot
Depth of Hold
8 ft
W
2
2Ji
2%
3
za
ZA
ins.
10 "
it
12 "
n
14 "
a
16 "
a
18 "
tt
20 "
<t
22 "
it
24 "
a
26 "
u
28 "
a
30 "
u
"It is suggested by the Rules Committee that the minimum free-
board for hurricane deck vessels should not be less than A or for
raised quarter deck vessels % of that indicated in the table.
"The depth of hold for regulating freeboard to be measured to
and the freeboard from, the second deck of hurricane deck vessels.
"The depth of hold for regulating freeboard to be measured to
y Google
MARKING FOR STEAMERS
221
and the freeboard from, the main deck of vessels having a raised
quarter deck."
In Great Britain a committee was appointed by the Board of
Trade in 1883, to formulate rules for the assigning of freeboard to
vessels. These rules were revised in 1906, and with slight altera-
tions remain in force today. Although Lloyd's assign freeboard to ves-
sels yet perhaps the final authority or rather the authority Lloyd's
follows are the regulations of the British Board of Trade.
Freeboards are measured from a horizontal line squared out from
the inner edge of a water way of assumed width (see Fig. 32). This
horizontal line is called the statutory deck line and the vertical
distance between it and the deck at the side the statutory allowance
which averages about % of the round of beam.
ftp ef£f&?ir?0ry
J
[zZJB^-
vtrttttrJ Tmefo
F W
WN*
The** meas^re/nentlf
to 6* taAe»fro/r>
centre o/a'/sc to
to/» cfeox* /i/te
\ ■ L- - f * ** *
/reetoaraf McrrX/rtf /or Steamers
\ffie»e /Heaw+yrreffs
st*Ae tvtke" front
centre of efisc /ofo/9
Same 0* f*r Steamers
/*^»rA
Po/to 0/T&
T?o»9 «
freetoaraf Mar/cwf for S a/7//?f Vesse/s
Figure 32. — Freeboard Markings.
Digiti
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222 SHIP CALCULATIONS
The freeboard regulations consist essentially of a number of
tables which give in feet and inches the freeboards of vessels of
any depth, within certain limits, that is vessels having a certain
ratio of depth to length. The tables only strictly apply to standard
vessels but provision is made for adapting them to those of various
types. (For calculations and the assumptions made see Freeboard
Tables, Board of Trade, London.)
Freeboard Markings. — Center of disk to be placed on both sides
of vessel amidships, i.e. at the middle length of the load water line.
The disks and lines must be permanently marked by center punch
marks or cutting. L R indicates Lloyd's Register. If the free-
board has been assigned by the Bureau Veritas the letters used are
B V. FW = Fresh Water, I S = Indian Summer, S - Summer,
W = Winter, W N A = Winter North Atlantic.
POWERING VESSELS
The following formulae apply to all power-driven craft except
hydroplanes. The results obtained should be compared with those
of actual ships as given in tables on pages 310-320.
To Find the Approximate I. H. P. to Propel a Vessel at a Certain
Speed.
Let H = indicated horse power of the engine
D = displacement in tons
V = speed in knots
K = coefficient for small launches = 100 to 150
yachts moderately fine and fair
speeds = 200
merchant vessels of moderate size = 220 to
250
larger vessels = 250 to 300
fast passenger boats = 220 to 280
torpedo boats = 200
cruisers and battleships = 200 to 250
Thenff = g and 7=^-^7==-
Example. It is proposed to build a freight steamer 280 ft. long, displacement
3800 tons, speed 10 knots. Find the approximate indicated horse power for the
engine.
Assume £ = 220
Then H = g X </» - 12 Xj^ggog, 1190
K 220
Digitized
by Google
EFFECTIVE HORSE POWER 223
Also for estimating the i. h. p. the following formula can be
used, but it does not apply favorably to fast vessels but is suitable
for low and moderate speeds. (See also paragraph in "Marine En- «
gines" on estimating horse power.)
H = i. h. p.
V = speed in knots
S = wetted surface in square feet
K — coefficient for short beamy ships = 6.
merchant vessels of ordinary form = 5.
fine ships = 4.
KXSXV*
Then H «
100000
Effective Horse Power (e. h. p.) at a given speed is the horse
power required to overcome the various resistances to a vessel's
progress at that speed. Calling these resistances R and the
R X Sf
speed in feet per minute S then the e. h. p. = Q>fflnn • The ratio
of effective horse power to the indicated horse power, viz. . '
at any speed, is the propulsive coefficient at that speed. For modern
vessels with fine lines a propulsive coefficient of 50% may be ex-
pected. In cases with extremely fine forms and fast running engines,
the percentage increases.
Towing. — To find the horse power required at a given speed, as,
for instance, when a tug is towing a barge.
R = resistance to motion in lb.
v = speed in feet per minute
V — speed in knots per hour
H = horse power
T. „ RXv RXV ,
Then//s= 33000= ^2G- nearly
Example. At a speed of 10 knots per hour (or 1013 ft. per minute) the tow rope
strain on a tug towing a barge was 10770 lb. Find the horse power necessary to
overcome the resistance of the barge Alone. Work done per minute in foot-
pounds = R X v = 10770 lb. X 1013 ft.
RXv 10770 X 1013 00/1
H =
33000 33000
17 X 27 X 45
A 158 ft. tug, engine 5^ L (see table of Excursion and
Harbor Vessels), can tow three barges of 1800 tons deadweight each
Digitized by VjOOQ 1C
224 SHIP CALCULATIONS
at a sea speed of about 7 knots per hour. A 90-ft. tug, engine
— — — , for harbor service can easily handle two square-ended
scows 90 ft. long by 30 ft. beam. In ocean towing, the barges
should be several hundred feet apart, as they tow more satisfactorily
in this way than close together.
To Find the Number of Revolutions of the Engine to Drive a
Vessel at a Certain Speed.*
P = pitch of the propeller in feet
S = required speed in knots
R = revolutions per minute at required speed
N = number of feet in a knot (6080)
8 = per cent of slip of propeller expressed as a decimal.
6080 X S
Then R, revolutions of engine
S the speed in knots =
60 X P X (1 - s)
60XPXflX(l-s)
6080
Example. The pitch of a propeller is 16 ft. How many revolutions must it
make to drive a ship at a speed of 10 knots per hour, the slip of the propeller being
estimated at 10%.
From the above formula the revolutions
r = 6080 XS 6080 X 10 ?ol/
60 X P X (1 - s) " 60 X 16 X (1 - .1) "" *
To Find the Number of Revolutions per Minute at Which to Run
the Engine to Give a Required Speed.*
R = revolutions* per minute for a given speed
S = given speed
Ri — required revolutions
Si = required speed
Then A -^|*
Example. If a vessel travels at the rate of 16 knots an hour when the engine
is making 64 revolutions per minute, what should be the number of revolutions
per minute to reduce the speed to 14 knots? The revolutions required are given by
the formula Ri = — = — substituting the above values, then — =-s — ™ 66 revolu-
a io
tions per minute.
Formula for Estimating the Speed of a Motor Boat
M — speed in statute miles per hour
L = length over all (feet)
♦From Mariner's Handbook
THRUST HORSE POWER 225
' B = extreme beam (feet)
P = brake horse power of engine
C = constant =9.5 moderate speed type
8.5 high speed type
- cVlxp
M £—
Thrust horse power, see Horse Powers.
Calculation of thrust, see Propellers.
Resistance. — The total resistance of a vessel is made up of fric-
tional resistance, eddy making, and wave forming. The eddy mak-
ing is about one-tenth of the frictional and does not exceed 5% of
the power required to drive a vessel. As to the wave forming, it
has been found impossible to formulate a practical law. Experi-
ments made by Mr. Froude in England showed that the frictional
resistance at a 6-knot speed is about J£ of a pound per square foot
of wetted surface for ordinary painted ship's bottoms, and that the
total resistance varies about as the square of the speed. Using
Froude's value for frictional resistance as % lb. per square foot at
6 knots, then frictional resistance of a vessel = square feet of wet-
ted surface X }i lb. per square foot X I ^ — I
, . resistance X speed in feet per minute
and horse power m^ K
The actual resistance of ship to progress through the water is
the e. h. p. (effective horse power) required, which is perhaps J^ of
the indicated horse power. Within the lower limits of power and
speed only the frictional resistance need be considered. The fol-
lowing applies in general from J£ to J£ full power.
1. The indicated horse power varies as the square of the speed.
2. Consumption of fuel varies as the square of the speed.
Example. If a steamer burns 40 tons of coal per day at a speed of 20 knots per
hour, how many would she burn at 21 knots?
40
The consumption per knot at 20 knots is — = 2 tons
Then the consumption per knot at 20 knots : to the consumption at
21 knots = square of the speed at 20 knots : is to square of speed
at 21 knots.
2 : x - 20* : 21*
2 X21» _ _ . . .
x — — 2oT~ = 2*2 ton8 P61" *cnot
or 21 knots V 2.2 tons = 46.2 tons per hour.
(Author not known.) •
Digitized by vjOOQIC
226 SHIP CALCULATIONS
3. Total fuel consumption for any distance varies as the square
of the speed times the distance.
At half-speed the frictional resistance will be only \i of the frac-
tional resistance at full speed. Since the power required to propel
a ship is proportional to the product of the frictional resistance and
the speed, it follows that the power delivered by the propeller is
proportional to the cube of the speed. Thus at half-speed the out-
put from the propeller is only y% of the output at full speed. This
relation is not exact but is nevertheless widely used in making ap-
proximate calculations, for the power required increases at high
speeds more rapidly than as the cube of the speed.
Table of Approximate Values for the Frictional Resistance
of Snips
Displacement in Tons
Frictional Resistance in Pounds
Per Ton at a Reference
Speed of 20 Knots
500
42
1,000
34
2,000
26
4,000
18-
8,000
12
16,000
9
32,000
7
From the above table it will be noted that for a given speed the
frictional resistance per ton gradually decreases with increasing size
of ship and attains a low value in large ships.
Example. Find the thrust horse power of a 4000-ton ship when at a speed of
22 knots.
From the table the frictional resistance at a speed of 20 knots is given as 18 lb.
per ton. For a speed of 22 knots the frictional resistance is
(!)'
4000 X I =gj X 18 = 87120 lb.
rvu ^ ^^ 87120 X 22 knots X 6080 ft.
Then thrust horse power = eo min. X 33000 lb. 59°° nearly'
The law of comparison, or Froude's law, states: "The resistances
of similar ships are in the ratio of the cubes of their linear dimensions,
when their speeds are in the ratio of the square root of their dimen-
sions." The speeds which are connected by this relation are
known as corresponding speeds. The law applies only to that re-
sistance for which the dynamic conditions are similar irrespective
Digitized by VjOOQ 1C
LAUNCHING
227
of size. However, this is not the case so far as fractional resistance
of a ship is concerned and the law does not apply to it. For this
reason the results of experiments with models have to be corrected
for friction when they are applied to the ship; (See Ship Forms,
Res. and Screw Propulsion, by B. S. Baker.)
Froude's Surface Friction Constants for Weli^Painted Ships
in Sea Water*
Length of
Vessel in
Feet
Coefficient
. of
Friction
Power
According
to which
Friction
Varies
Length of
Vessel in
Feet
Coefficient
of
Friction
Power
According
to which
Friction
Varies
/
n
/
n
100
120
140
160
180
200
250
300
.00923
.00916
.00911
.00907
.00904
.00902
.00897
.00892
1.825
1.825
1.825
1.825
1.825
1.825
1,825
1.825
350
400
450
500
550
600
.00889
.00886
.00883
.00880
.00877
.00874
1.825
1.825
1.825
1.825
1.825
1.825
Let / = coefficient of friction from the above table
8 = wetted area in sq. ft.
V = speed of vessel in knots per hour
R — frictional resistance
Then R =fSVn -/SF1*
( 71826 » i0g y X 1.825)
LAUNCHING
Care must be exercised in the building so that when a vessel is
ready for launching there are no heavy weights on deck or high
above the keel. For a vessel in the launching condition has a light
draft, great freeboard, and a high center of gravity. An estimate
can be made of the metacentric height and if this is not sufficient
the ship should be ballasted to lower the center of gravity. A
minimum height of transverse metacenter above the center of
gravity, of one foot, should be provided in the launching condition.
Vessels are launched either stern first or sideways, the latter
being the practice on the Great Lakes (U. S.). Where there is a
considerable rise and fall of the tide, the launching ways extend
♦From Naval Architecture, C. H. Peabody.
Digiti
zed by G00gk
228 SHIP CALCULATIONS
usually to the level of the water at low tide, but in cases where the
tidal rise is small it may be necessary to carry them further out.
The ways for vessels to be launched stern first should be so
located under the hull that they come under a longitudinal or a
keelson. The breadth of the ways depends on the launching weight.
To determine the breadth,
Let W = launching weight in tons
I = length of cradle or sliding ways, which is about .8 the
length of the vessel
b « breadth of each way
area of sliding ways = 2 6 X I
W
Then the average pressure per square foot on the ways = —
The area of the ways should be such that the pressure per square
W
foot is not more than 2.5 tons. Thus let 2.5 = 7 — hence the
Zo X *
breadth of each way = . . . . — ,J~ e — -rp. See Launching Data.
5 X length of cradle &
The declivity of the ways should be' from ^ of an in. to the
foot in large vessels to % in small. The camber or longitudinal cur-
vature is from 12 to 15 ins, in 500 ft.
In launching there are two critical periods: first, when the center
of gravity has passed over the ends of the ways, for there is then
little support aft and the ship has a tendency to turn about the after
end of the ways and so concentrate the weight at that point; and
second, when the buoyancy aft is sufficient to lift the ship and cause
her to turn about the fore end of the cradle, there is then a long
length' of structure unsupported and a great pressure is exerted over
a short length at the fore end of the cradle and the launching ways.
Launching Calculations.* — Assuming that the vessel has no tip-
ping moment but gradually lifts aft as she launches, when she is
almost entirely in the water — say when the fore poppet is over the
end of the standing ways — the force of buoyancy pressing upward
will react at the fore poppet, causing a downward pressure on the
ways, tending to spread out the standing ways, to break the fore
poppets, or to crush in the bows of the vessel.
For calculating this pressure, first find the declivity of the ship
on the ways, and of the launching ways, and also the position of
the upper fine of the standing ways from the keel of the ship. As-
certain the depth of water expected on the day of the launching.
* From A Class Book of Naval Architecture, W. J. Lovett.
Digitized by VJiOOQ LC
-*-•
\
*F?J?
229
Digiti
zed by G00gk
230 SHIP CALCULATIONS
Make a tracing of the ship to a small scale (see Fig. 33), and di-
vide it into displacement ordinates. Calculate the area of each
section up to the several water planes and draw curves of areas at
each section.
Arrange for different positions of the ship. Place the tracing
on the first shift on the drawing (say 250 ft.) and find the volume
of displacement of the ship in the water, and the position of the cen-
ter of buoyancy from the after perpendicular. Do likewise for 300-,
350- and 450-foot shifts, or the shifts could be 25 ft. apart, if desired,
instead of 50.
Estimate the longitudinal position of the center of gravity of the
ship. (See Center of Gravity.) Set up to scale the moment of
weight about the fore end of the sliding ways or fore poppet. This
is obtained by multiplying the weight of the ship by the distance
of the center of gravity from the fore end of the ways. Next find
the moment of buoyancy about the fore end of the ways. This is
obtained from the equation
Moment of buoyancy about the fore end of ways =
volume of displacement X center of buoyancy from fore end of ways
35
35 cubic feet of salt water = 2240 lb. = one ton.
Do this for each shift. Set off to the same scale the various values
found for the moment of weight and the moment of buoyancy, and
where they cross each other the ship will commence to rise.
Set up the displacement at each shift and draw a displacement
curve. Find the displacement at the point where the ship com-
mences to rise. The difference between the displacement of the
ship in the water and the displacement when she begins to rise,
gives the weight bearing on the fore poppet. Find the moment
of the weight about the after end of the standing ways. Also find
the moment of buoyancy about the after end of the standing ways
for each shift. Draw curves as in Fig. 34. If the curve of moment
of buoyancy cuts the curve of moment of weights about the after
end of standing ways, there will be a tipping moment, but when they
do not cut there is a lifting moment. The different shifts are ob-
tained by shifting the center of gravity of the vessel so many feet
aft. The moment of weight about the after end of the ways is
calculated by multiplying the weight of the ship by the distance
of the center of gravity from the end of the ways at the different
shifts. Thus when the center of gravity is exactly over the end of
the ways, and the displacement taken at say 6000 tons, there would
Digitized by VjOOQ 1C
MOMENT OF BUOYANCY
231
be no moment of weight about the after end, because 6000 multi-
plied by the distance of the center of gravity from the after end
of ways, which is 0, is 0. At the 50-foot shift the moment will be
6000 X 50 = 300,000 foot-tons, etc.
y\
111
TO!
//&#?&,*£/
rajs*7
The moment of buoyancy is calculated by multiplying the actual
displacement at the different shifts by the distance of the center
of buoyancy of the various displacements from the end of the
ways. The Weight on the fore poppets is obtained by reading the
displacement when the ship begins to rise, which in Fig. 34 is at x.
The displacement is 0 P. Subtract O P from the displacement at
the launching draft and the difference will be the weight on the fore
poppets.
tipping moment
weight of ♦ship
The tipping lever diyided by the length of the ship should have a
certain ratio. A ratio of 1/18 is quite safe, but if more than 1/11
there is likely to be trouble.
Releasing, Starting and Checking Devices. — The former often
consists of two dog shores with their heads toward the bow of the
vessel and caught under a piece fastened to the sliding way. The
heads and the bearings for them should be covered with steel plates.
The dog shores are knocked down by simultaneously dropping
weights on them, the weights being suspended by a single rope which
on being cut will cause both to drop at the same time. A vessel
may also be released by sawing through the sliding ways that have
Digitized by vjOOQ 1C
Tipping lever =
232
SHIP CALCULATIONS
been extended and fastened at the shore ends. Care must be taken
that both planks are sawn at the same rate.
Should the vessel refuse to start when released, a hydraulic ram
or jack- may be brought to bear at the end of each launching way,
and also against the stem.
To check the vessel after she has left the ways, hawsers are
made fast to the hull, which are fastened to heavy chains on shore
that are laid in piles at intervals. To prevent snubbing by sudden
stopping, hawsers may be carried beyond the bitts and lashed at
intervals to another hawser on the deck, the lashings being torn
away as the vessel continues to move, thus gradually bringing her
to rest. In some instances a wooden shield is fixed at the stern,
but care must be taken that the shield has not such an area that the
vessel will be stopped on the ways when only partly waterborne.
Launching velocities vary from 13.7 to 17 ft. per second, and the
distance run at these velocities is about % of the length of the vessel.
The above applies to end launching, that is, stern first, which
is the usual practice. For side launching the ways 'are given a
steeper incline, and instead of only two there are several. One of
the advantages of side launching is that the vessel may be built
on an even keel.
Launching Data
Paddle
Wheel
Steamer,
190' X
22' X
9'
Screw Steamer
234' X
33' X
18'
270' X
34' X
19'
330' X
43M' X
30^'
360' X36'
X28'
400' X42'
X29H'
Declivity of keel per ft
Declivity of standing
ways per ft
Camber of standing ways
Length of standing ways
Length of sliding ways .
Breadth of sliding ways.
Area of sliding ways in
square ft
Total fall in length of
standing ways
Water on way ends ....
Draft of ship forward . . .
.Draft of ship aft
Mean draft..
Displacement in tons. .
Mean pressure per sq
ft. on sliding ways in
tons
A* ,
IS to At
8*
195'
160'
1'3*
375
12' 0*
2' 9"
4'0*
3' 10"
3' 11*
215
.57
AtoM
l'Q*
267'
180'
1'9*
630
ISM*
2' 8"
5' 9"
9'0*
V 4^*
. 865
1.37
a to n
1' 10*
300'
200'
1'9*
700
15' 6*
3' 7*
5' 7*
10' 8*
8' m»
1000
1.40
A toil
I'll*
348'
240'
l'lO*
880
21' 6*
3' 9*
6'6V^*
9' 5 1 2*
8'0*
1660
1.
l'O*^
367'
284'
1'9*
994
18' 9*
6'0*
11' 6*
14' 0*
12' 9*
2500
2.51
Atott
1'2*
395'
330'
1'9*
1155
19' 7"
4' 4*
7/0*
10' 10^*
9'03£*
2157
Above table from Design and Construction of Ships, J. H. Biles.
Digitized by VjOOQ 1C
U. S. BATTLESHIP "ARIZONA"
233
U. S. Battleship "Arizona," 600. ft. water line, 97 ft. beam, launching
weight exclusive of cradle and ways 12,800 tons, total weight on
grease 13.350 tons, sliding ways and cradle 70 ins. wide, effective
length 505 ft., initial pressure per square foot on the grease 2.27
tons, maximum observed velocity 21 ft. per second, was afloat in
about 42 seconds.
Freight steamer "Chokyu Maru," 277 ft. 7 ins. O. A., 268 ft. between
perpendiculars, beam molded 40 ft. 9 ins., depth molded 23 ft. 6 ins.;
draft loaded 19 ft. 9% ins., designed displacement 4887 tons, dead-
weight 3067 tons, engine 19 X 3*^ X 52, i. h. p. 1060, speed 11
knots.
Declivity of keel blocks 1/17
Declivity of launching Ways 1/16
Length of sliding ways 217 ft.
Width of sliding ways 1 ft. 9 ins.
Width of standing ways 2 ft.
Center to center of sliding ways 14 ft. 6 ins.
Average pressure on standing ways 1.35 tons
Maximum pressure on fore poppet when the stern
lifted 315 tons
Height of water at the end of standing way 5 ft. 6 ins.
Launching speed ' 16.2 ft. per min.
Launching weight, including cradles 1033 tons
Average draft when afloat 4 ft. 7}^ ins.
Displacement when afloat 971 tons
Center of gravity of the hull and cradles, .83 ft. aft amidships
Declivity op Ways and I<aunching Velocity
Length of
Launching
Declivity
Declivity
Vessel
Weight
of Ways
of Keel
in Feet
in Tons
per Foot
per Foot
200
200
H
tt
280
1,000
A
H
300
2,200
A
A
430
4,000
Yt
460
5,000
X
H
500
7,000
A
A
Camber
of Ways
Launching
Velocity
Feet per
Second
none
6 ins. in 300 ft.
9 ins. in 400 ft.
14 ins. in 560 ft.
12 to 13
15 to 17
18
16
-
SECTION V
HULL CONSTRUCTION
CLASSIFICATION SOCIETIES AND ORGANIZATIONS
GOVERNING SHIPPING
Merchant vessels are built and maintained under the rules pre-
scribed by any of the following societies: Lloyd's Register, Amer-
ican Bureau of Shipping, British Corporation, Bureau Veritas;
and Norske Veritas. By so doing the owner can get more favorable
insurance rates than if his vessel had not been constructed and
was not kept up to the requirements of one of the above societies.
Motor boats, that is, small pleasure and commercial craft, are not
built according to any rules, and are consequently not classed.
Lloyd's Register of Shipping, founded in 1760, is the largest and
oldest society. Its head office is in London, England, with branches
all over the world. In the case of a new vessel intended for classi-
fication, the plans are first submitted to be approved by the Com-
mittee and the building proceeds under the supervision of a local
surveyor. No steel is used which has not been produced at approved
works and tested at the works by the surveyors. When com-
pleted a character is assigned to the vessel by the Committee upon
the surveyor's report.
Vessels built according to Lloyd's Register and classed with
the Society are required at intervals of four years to be given special
surveys. These surveys are designated as Nos. 1, 2, and 3, and
as long as the vessel maintains her structural strength she keeps
her class.
Lloyd's Register issues annually to its subscribers a register book
containing particulars of all seagoing vessels of 100 tons and up-
wards, including those to which classes have been assigned. The
figure 1 after the character assigned to a vessel thus, 100 A 1, de-
notes that her equipment is in good condition and in accordance with
the rules of the Society. The star or cross before the figure denotes
that the vessel was built under special survey. If the engines and
boilers were built and installed according to the rules, then it is
Digitized by \J\JU\?Lt
SHIPPING 235
registered thus in the book »J« L M C. The highest rating is
-f 100 A 1 *%* L M C.
Lloyd's, the headquarters of the British Underwriters (an organ-
ization entirely separate from Lloyd's Register of Shipping), was
incorporated by act of Parliament in 1871, for the carrying on of
the business of marine insurance by members of the Society. It
comprises about 600 underwriting members and about 200 non-
underwriting members> besides some 500 annual subscribers.
The underwriters pay a large entrance fee and an annual subscrip-
tion, and to place their credit beyond a doubt, they are required
to deposit as a minimum $25,000 as security with the Committee
* of Lloyd's. A primary object of the society is the protection of
the interests of members in respect of shipping, cargoes and freight.
By no means the least important function of Lloyd's is "the
collection and diffusion of intelligence and information bearing on
shipping matters." It has agents all over the world, but these
agents are not insurance agents; in fact they are strictly forbidden
to act as such. Their dutie3 may be broadly defined as follows:
In case of shipwreck to render to masters of vessels, of which
there are over 40,000 certificates in the British mercantile marine,
any advice or assistance they may require. Moreover they are
required to dispatch every item of information likely to be of in-
terest to the members of Lloyd's by the most expeditious route,
telegraphic or otherwise, during the day or night, Sunday and
weekday. It is thus that Lloyd's is enabled to compile and print
and issue numerous large and instructive books and pamphlets.
American Bureau of Shipping. — This society was incorporated
by Act of the Legislature of the State of New York in 1862, for the
purpose of collecting and disseminating information upon subjects
of marine or commercial interest, of encouraging and advancing
worthy and well qualified commanders and other officers of vessels
in the merchant service, of ascertaining and certifying the qualifi-
cations of such persons as shall apply to be recommended as such
commanders or officers, and of promoting the security of life and
property on the seas. Home office in New York.
Vessels built in conformity with the American Bureau of Shipping
Rules and under its inspection are classed thus:
First Class A 1 for 20 years.
Second Class A 1 for 16 years.
Third Class A 1 for 12 years.
i
Digiti
zed by G00gk
236 HULL CONSTRUCTION
If built under special survey there is a prefix +. If the machinery
passes the requirements it is indicated in the registry book of the
society as M. C.
British Corporation. — The British Corporation for the Survey
and Registry of Shipping was founded in 1890 for the purpose of
providing for the classification of steel ships and the registration
of vessels classed with the Society, and was appointed by the Board
of Trade (English) to approve and certify load lines under the
Merchant Shipping Acts.
The registry is under the control of the Committee of Manage-
ment which is composed of shipowners, engineers, shipbuilders and
representatives of underwriting and other associations, and is in-
corporated under articles of association wherein provision is made
that the funds of the Society cannot become a source of profit to
any member or to any person claiming through any member of the
corporation. The head office is in Glasgow, Scotland.
In the British Corporation Rules, items of longitudinal strength
have their scantlings determined by the length of the vessel in
conjunction with either breadth or depth. Items of transverse
strength have their scantlings determined by length or breadth, or
both combined, no numbers being used, the dimensions alone de-
termining the scantlings. For example, a vessel 400 ft. long requires
twenty-five fortieths of shell plating. Vessels built under these
rules and surveys are classed B. S.* If not under survey but
under the rules they may be classed B. S. There is only one class
and not several, as 100 A 1, 100 A, etc., as in Lloyd's. The ma-
chinery requirements are confirmed with the letters M. B. S.
The highest class a steamer can receive is B. S.* M. B. S.*
Bureau Veritas. — This Society has been recognized in France by
decree of the Minister of Marine Sept. 5, 1908, for carrying out
the law of April 10, 1907, regarding the safety of marine navigation.
Vessels holding the highest class of the Bureau Veritas are exempt,
in obtaining permits of navigation, from examination and tests in
connection with the hulls, engines, and boilers and their accessories;
that is to say, on points which are covered by the surveys pre-
scribed in the present classification rules.
The Bureau Veritas British Committee has been delegated by
the Board of Trade in conformity with the Merchant Shipping Act
of 1894 to assign and mark load lines on their behalf on British
vessels, also on vessels of other nationalities trading to British
ioogle
BOARD OF TRADE 237
ports and which are not provided with freeboard certificates and
its marks are recognized as equivalent to British requirements.
Vessels are divided into three divisions, viz., I, II, and III. In
order to retain their class, vessels must be subjected to the inspec-
tion of a surveyor to the Bureau Veritas at the following periods:
Vessels of the I division every 4 years.
II division every 3 years.
Ill division every 3 years.
The large I denotes first division classification (out of three).
Two rings around the (p indicate that the ship is divided into a
sufficient number of watertight compartments so she will float
with any two in communication with the sea. Very few vessels
have the double ring, but some have the single ring ®y indicating
they can float with any one compartment in communication with
the sea. '/s denotes completeness and efficiency of hull and machin-
ery; the letter following 8/3 indicates the navigation for which the
vessel is intended for. The first I shows that the wood parts of
the hull are entirely satisfactory and the second I refers to the
masts, spars, rigging, anchors, chains and boats. Thus a vessel
built to the highest class would be given the following characters
+ 0»A L I.I.
Norske Veritas. — This Society was established in 1864 by various
marine insurance clubs of Norway, who prior to its establishment
had separate surveyors of their own. A large number of Nor-
wegian vessels are built according to the rules of this society.
I A I denotes compliance with the rules in regards the hull. M
& K. V. signifies that the boilers and engines comply. The third
figure, I, denotes the efficient state of the equipment, and the +
that the vessel was built under special survey. Thus a vessel built
to the highest class would be registered thus + I A I I +M&
K. V.
Reglstro Nazionale Italiano was formed in 1910 to take over the
Registro Italiano which was founded in 1861. The society has
adopted the rules of the British Corporation, and has an arrange-
ment with the British Corporation by which it can use the services
of that society in British and foreign ports.
Great Lakes Register. — Rules under which steamers to ply on the
Great Lakes, North America, are built.
Board of Trade. — Although not a classification society, yet the
Board of Trade is the final authority on British marine matters.
The Board of Trade gets its authority from the Merchant Shipping
Digitized by vjOOQ 1C
238 HULL CONSTRUCTION
Act of 1894. It has passed regulations on many important subjects
as freeboard, tonnage, bulkheads, etc. Referring to freeboard, it
has published tables giving the freeboard of vessels, and has granted
the right to assign freeboards to Lloyd's, Bureau Veritas, and the
British Corporation.
United States Steamboat-Inspection Service, a part of the Depart-
ment of Commerce with headquarters at Washington, D. C. It
has inspectors at all the large shipping cities in the United States.
Rules and regulations are published by it pertaining to the construc-
tion and inspection of boilers, lifeboats to be carried, wireless equip-
ment, and other matters relating to the equipment and running of
motor boats, sail and steam vessels.
TYPES AND STRUCTURAL FEATURES OF
MERCHANT VESSELS
The rules published by Lloyd's Register of Shipping, American
Bureau of Shipping, Bureau Veritas, or other society, specify the
size of the frames, beams and other structural members. In Lloyd's,
for obtaining the scantling numeral which gives the sizes of the dif-
ferent members, the dimensions used are length (see page 166),
molded breadth and depth, the latter varying with the type of
vessel. In Bureau Veritas the same dimensions are used, but in
the American Bureau of Shipping the half-breadth and half-girth
are also included in making up the scantling numeral. The differ-
ence in the frames, beams, etc., for a vessel built according to any
society is slight, but there is variance in the height of the bulkheads.
Broadly speaking, merchant vessels have their machinery amid-
ships, the chief exceptions being tankers, colliers, and lumber car-
riers. They have double bottoms which are often utilized for
carrying oil fuel and water ballast. For ships which have to make
long voyages in ballast, top side tanks together with the usual
double bottom give a good distribution of the ballast weights.
Merchant' vessels, according to Lloyd's, can be divided into the
following classes: shelter, awning and bridge deck, one, two, three,
etc., deck vessels and sailing vessels. The only reduction allowed
in the above by Lloyd's is in the shelter, awning and bridge deck
classes. In all cases the uppermost continuous deck has the heaviest
scantlings whether shelter deck or otherwise. Freeboard on these
ships where there are no regular tonnage openings is practically the
same as on a full scantling freighter.
Digitized by VjiOOQIC
MERCHANT VESSELS
239
"S
3
S/s?jp/& JD&cA *///? poo/° , 6r/atyeA /toreearst/e
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Figure 35. — Typea of Merchant Vessels.
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240 . HULL CONSTRUCTION
Shelter deck vessels (see Fig. 35) are usually three deck vessels
with a complete erection all fore and aft inclosed from the sea with
the exception of a few openings for ease in loading and discharging
cargoes. They have on the upper or shelter deck at the middle
line one or more openings which are not fitted with permanent
means of closing like ordinary covered hatchways.
A shelter deck as now constructed in large vessels is a super-
structure extending all fore and aft. The peculiar feature is, that
the 'tween-deck space it incloses is not included in the vessel's reg-
ister tonnage, this omission being allowed by the existing British
tonnage laws on the condition that somewhere in the deck there
is an opening with no permanent means of closing it, and that no
part of the 'tween-deck space is partitioned off or closed in a per-
manent manner. The necessary opening, referred to as the tonnage
opening, may be formed by one of the hatchways, usually the
after one which may or may not have coamings, but it must not
have any permanent means of being closed. Sometimes a special
hatchway is provided about 4 ft. long by half the beam of the ship.
Shelter deck vessels built to Lloyd's must have the strength
members carried to the level of the shelter deck. When there are
no tonnage openings the vessel may be loaded proportionately to
the structural efficiency of the upper works. When there are ton-
nage openings in the shelter deck and transverse bulkheads are lo-
cated in the 'tween-decks closely adjacent to the openings, the
freeboard has been approximated to that of the normal awning deck
vessel. Shelter deckers are largely used for carrying cattle, and
also as bulk oil carriers. See Fig. 40.
One, two, three, etc., deckers have no awning or shelter decks
with tonnage openings but continuous decks. These vessels have
the heaviest scantlings of any built, and are designed to engage in
ocean trading with the minimum amount of freeboard.
Sailing Vessels. — Here special attention is given to the transverse
strength, heavy webs being fitted in way of the masts. The shell
plating is increased .10 in. when the longitudinal number exceeds
11,000 and when the number is over 13,000 three strakes at the
bilge are increased .06 in. Other special stiffening in the shape of
diagonal tie plates in way of the masts and special panting stringers
at the ends.
Hurricane deck vessel is an American term of a type built to
the rules of the American Bureau of Shipping, This type is divided
into two classes, viz., one for engaging in the transatlantic and
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TURRET VESSEL
241
Figure 36. — Midship Section of a Turret Vessel.
general ocean trade (corresponding in many respects to Lloyd's
shelter deckers except in the heights of the bulkheads) and the
other for engaging in the coastwise trade, as from New York to New
Orleans, the latter having lighter scantlings than the former. In
all hurricane deckers, the depth is taken from the top of the keel
to the top of the second deck beam amidships at middle line, and
the collision bulkhead extends only to the second deck.
The important difference between the two classes is in the fram-
ing. Vessels built for the transatlantic trade have all their frames
extend to the hurricane deck, while those for the coastwise extend
alternately to the second and hurricane decks except for one-sixth
of the length from the bow where every frame extends to the hurri-
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242
HULL CONSTRUCTION
cane deck, but in no case need this exceed 60 ft. As to the reverse
frames for the transatlantic they extend to the under side of the
hurricane deck stringer, and for the coastwise for a certain length
alternately to the hurricane deck.
Raised Quarter Deck. — Here (see Fig. 35) the main deck is raised
3 ft. for vessels up to 100 ft. in length, 4 ft. up to 250 ft. and 6 ft.
up to 400 ft. Although it is customary to speak of the raised quarter
deck being aDove the main deck, yet neither plates nor beams are
fitted at the main deck immediately under the raised quarter deck
except for a short distance at the forward end or at the "break,"
as it is often called. Practically what has been done is to raise up
the main deck for part of its length. This construction is par-
ticularly suitable for vessels of about 250 ft., where the machinery
is amidships, for it gives additional space in the after hold (which
Figure 37.-
-Midship Section of a Trunk Vessel.
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bogle
WAR VESSELS 243
is often limited by the shaft tunnel) and thereby prevents a steamer
from trimming by the head, as the after hold is larger than the
forward.
Turret Vessels. — See Fig. 36. These were originally designed to
save tonnage under the Suez Canal system of measurement. They
are popular in the Far East trade and are relatively stronger than
the ordinary* ship of the same dimensions owing to the turret sides.
They have a continuous center turret which forms with the harbor
deck an integral part of the hull. They are built without sheer,
and may have on the top of the turret deck erections as poop,
bridge, and forecastle, or such erections may be on the harbor deck,
but in this case the turret must be continuous from the poop to
the forecastk into which it is scarped. Cutting away the outboard
parts of the upper 'tween-decks served the double purposes of re-
ducing the tonnage measurement and port charges, and providing
a center trunk that served as an expansion chamber and made the
vessels self-trimming when loaded with grain or similar cargoes.
They are inferior in stability to the usual type when heeled to an
excessive angle.
Trunk Vessels. — These (see Fig. 37) are a modification of turret
vessels and are of the heaviest type. They have on the upper deck,
in addition to the poop, bridge', and forecastle, a continuous trunk.
WAR VESSELS
The war in Europe (1914r- ) showed particularly the advantages
of certain types of war vessels, viz., submarines, torpedo boat de-
stroyers, and battleships, while others which were at one time
looked upon as important have proved to be of little use. With
no intention of discussing the advantages and disadvantages of
every type, yet there stand out preeminently submarines for prey-
ing on merchant vessels, torpedo boat destroyers for patrol pur-
poses and to war on submarines, and battleships for shelling land
fortifications while troops are landing. Modern sea fights between
armored ships are fought at ranges of 3 or more miles, the guns in
many cases being elevated so projectiles will drop on the decks,
thus causing more damage than if fired directly at the sides which
are heavily protected by armor.
Aside from the special types of construction for the different classes,
there should be noted the method of propulsion and the fuels.
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244 HULL CONSTRUCTION
Referring to the former there has been a notable use of steam tur-
bines either driving the propellers direct or by gears; or the turbines
may be connected to generators which furnish current to electric
motors that propel the vessel. See Electric Propulsion.
Operating conditions for war vessels are different from those of
merchant. In war vessels it may be necessary to drive the vessel
at maximum speed at a very short notice, hence the importance of
water tube boilers for raising steam quickly. Then again a warship
must have machinery that is economical in the consumption of
fuel for long distance cruising. Diesel engines have been installed
chiefly in submarines. As to fuels, many warships are equipped
for either coal or oil. The chief advantages of oil being that it is
easier to stow and contains more heat units per pound, thus giving
a larger steaming radius.
In the United States Navy all large vessels are framed on the
longitudinal system (this does not mean on the Isherwood system),
the keel being continuous as also the fore and aft members on either
side called longitudinals, while the frames are intercostal. This
system of framing is carried out from the keel to the protective
deck including the inner bottom which extends as far forward and
aft as possible. Above the protective deck the transverse members
are continuous. Forward and aft of the inner bottom the frames
are continuous on both sides of the vertical keel and the longitudinals
are intercostal between them.
In torpedo boats and small vessels having no inner bottoms the
frames are continuous from keel to 'gunwale, and closely spaced
to support the shell plating. Here the longitudinals are intercostal.
No standard rules, as Lloyd's or British Corporation, are followed,
the U. S. Navy Department, Admiralty, and the various Govern-
ment Navy Departments drawing up their own plans and specifi-
cations.
Armor. — This may be divided into: (1) broadside extending
fore and aft sufficiently to cover the ammunition rooms and the
machinery space; (2) armored transverse bulkheads dividing the
ship into watertight compartments; (3) armor around the large
guns which are mounted in turrets; and (4) a protective deck.
The armor on the sides has a cement backing, back of which is the
hull plating that in turn is reinforced with heavy frames. The
armor is bolted to the hull by bolts screwed into the back of the
• armor. The outer face is given a hard surface while the rear has
a much softer one and possesses different properties. The manu-
y Google
THE PROTECTIVE DECK 245
facture of a plate either by the Harvey or Krupp process requires
great care and from 4 to 9 months, depending on the thickness.
Plates made by either process are alike; that is, they have a hard
outer surface to resist the penetration of a projectile and a tough
back to prevent the shattering of the plate by the impact. The
turret and barbette armor are supported by heavy structural
shapes and plates.
The protective deck consists of special treated steel plates about
23^ ins. thick that slope upwards from the sides of the vessel to a
flat portion amidships or the deck may extend straight to the shell
plating. See Fig. 38. This deck serves to protect the machinery
and other parts below it.
As an example of the armor of a battleship take the U. S. battle-
ship Nevada, one of the latest types (1916). The main armor belt
is 13 J^ ins. thick from its top to 2 ft. below the designed water
line, whence it is tapered uniformly to 8 ins. at the bottom. Aft
of the main belt the armor is 13 ins. The forward athwartship
armor and aftermost armor bulkhead is 13 ins. The barbettes are
13 and 4J^ ins. thick, the latter being amidships and out of reach of
the guns of the enemy. There are 4 turrets, 2 having 3 guns each,
and the other 2 having 2. The 3-gun turrets have 18- and 9-inch
armor and the 2-gun, 16 and 9. The armor is of the Krupp type.
There is also a protective deck.
Armament. — Under this heading are included the guns ranging
from the 15-inch mounted in the turrets of battleships to light
saluting guns and also torpedoes. Naval engagements are now fought
at long ranges and this is due to the development of the modern
high-powered gun, which brought about the building of the all big
gun or Dreadnaught type of battleship.
In the British Navy, 15-inch guns have been installed (Royal
Sovereign class, 10 15-in., 16 6-in., 12 3-in. or 12-pounders) while
the largest in the United States (1916) is 14 in., altho battleships
designed to carry 16-in. guns have been authorized. A popular
British gun is the 9.2 and a U. S. is the 6-inch, which are largely to
repel the attacks of torpedo boats and submarines.
The ammunition is either loose, that is, the powder and the pro-
jectile are put in the gun separate, or fixed, the powder being in a
brass case to which the projectile is fastened. Guns 5 ins. and over
generally use loose ammunition. On some battleships 14-inch
guns are mounted, firing a projectile weighing about 1,200 lb. and t
requiring 500 lb. of powder. The powder and projectiles are
Digiti
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246
HULL CONSTRUCTION
stored in ammunition rooms and are brought up to the men operating
the gun by hoists driven by electric motors or through tubes oper-
ated by compressed air. The guns in the turret are raised and low-
ered and the turret turned by electric motors, the turret with its
armor and guns resting on rollers. Guns using fixed ammunition
are divided into rapid fire, semi-automatic and automatic.
Torpedo tubes are of two types, one where the tubes are on deck
and the other where they are below the water line, the former for
torpedo boats and the latter for submarines, cruisers, and large
war vessels. The torpedoes are discharged from the deck tubes by
—9S'-&i '3ean to outside <fart
Figure 38. — Midship Section of a Battleship.
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Google
BATTLESHIPS 247
a small charge of powder, but after they have cleared the tube and
the side of the vessel they travel by their own motive power operated
by compressed air. The driving mechanism for keeping the tor-
pedo in a straight line and at a given distance from the surface is
very complicated. At the front is the warhead, which contains the
high explosive (generally gun cotton) that is discharged when the
torpedo strikes a ship . Torpedoes are 20 feet or more long, 20 ins.
or so in diameter and have a range of 2 or more miles. Deck tor-
pedo tubes are now mounted in pairs, the two tubes being placed
side by side. Torpedoes from underwater tubes, as fitted on sub-
marines and other war vessels, are discharged by compressed air,
the pressure being about 1,200 to 1,800 lb. per square inch. The
range and when to fire are given from the central station.
Warships may be divided into the following classes:*
Battleships. — Designed to fight the most powerful ships of an
adversary and thus having the heaviest armor and armament.
Displacement 11,000 to 40,000 tons, speed 16 to 25 knots. The
term "Dreadnaught" is often applied to a modern battleship,
which simply means that she has four or more turrets with at least
13-inch guns, with a secondary battery of 5- or 6-inch. In the
United States Navy the large guns are in turrets located on the fore
and aft center line, while in some European countries the turrets
are on each side (port and starboard). In some U. S. battleships
having four turrets, two turrets have three guns each, and the
other two, two guns. In the four battleships authorized in 1916,
each will have a main battery of 8 16-in., 45 cal. guns. As to
armor this is the heaviest carried by any vessel; in fact the weight
of the armor is about 26% of the displacement. The following
table gives fair values of the weights of armor, hull, etc., of a
battleship.
Item
Weight as Percentage of
Total Displacement
Hull
Armor
Armament
Propelling Machinery.
Coal
General Equipment. . .
35.0
26.0
19.0
10.5
5.5
4.0
100.0
* This division based on one in Naval Construction, by R. H. M. Robinson,
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248 HULL CONSTRUCTION
English battleships are fitted with torpedo nets as a protection
against torpedoes when at anchor. One of the latest types of U. S.
battleships is the Pennsylvania^ laid down in 1914. Length over
all 625 ft., water line 600 ft., beam 97 ft., draft 28 ft. 10 ins., normal
displacement 31,400 tons, turbines 31,500 h. p., speed 21 knots,
oil fuel only. Has 12 14-inch guns (3 in each turret), 22 5-inch,
4 3-pounders, 4 21-inch submerged torpedo tubes, 16-inch armor
belt amidships. One of the latest (1915) English battleships, viz.,
the Royal Sovereign, has' 15-inch guns. Length 630 ft., beam 95
ft., displacement 29,000 tons, turbines 44,000 h. p., speed 22.5 knots,
bunkers 4,000 tons of coal. Ten 15-inch guns, 16 6-inch, 12 12-
pounders, 5 torpedo tubes, armor belt 13 J^ ins., protective deck,
3 ins.
Battle Cruisers or Armored Cruisers. — Expected to do some
advance duty, but capable of taking position in line with battle-
ships. Have a displacement equal to a battleship, carry heavy
guns with lighter armor but have a speed of 22 to 31 knots. In
many instances it is difficult to distinguish between an armored or
battle cruiser and a battleship. A typical example is the Tiger
(Great Britain) laid down in 1913. She is 725 ft. over all, 87 ft.
beam, maximum draft 30 ft., displacement normal 27,000 tons,
full load 31,000, complement 1,000 men, turbines of 75,000 h. p.,
speed 27 knots, coal normal 1,000 tons, maximum 3,500 plus 1,000
tons of oil. Has 8 13.5-inch guns, 16 4-inch, 2 submerged torpedo
tubes on broadside and 1 at stern, 9-inch belt amidships, 4 ins. at
ends.
Monitors. — For coast and harbor defense, are now obsolete.
Had a single turret with 12-inch guns and a secondary battery of
G- and 4-inch, small freeboard and low speed. U. S. Ozark (1900),
253 ft. water line, 50 ft. beam, 12 ft. 6 ins. draft, displacement full
load 3,356 tons. Two 12-inch guns, 4 4-inch, 3 6-pounders, armor
belt amidships 11 ins., at ends 5 ins., speed about 11 knots.
Light Cruisers. — These include cruisers with light side armor
of 2 or 3 ins. and with a protective deck, and those without any side
armor and with only a protective deck. The heaviest gun usually
carried is a 6-inch. Light cruisers range from about 3,000 to
10,000 tons displacement, are speedy and are primarily for preying
on merchant vessels, while in times of peace they are largely used for
official business, such as representing their Government at a cele-
bration at a foreign port. Below are descriptions of two light cruis-
ers, one with side armor and the other without. Nottingham,
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TORPEDO BOAT DESTROYERS 249
British (1914), 430 ft. between perpendiculars, 49 ft. 10 ins. beam,
displacement 5,400 tons, Yarrow boilers, Parsons turbines of 22,000
h. p., speed 24.75 knots, coal 650 tons, can also carry oil, 9 6-in.
guns, 4 3-pounders, 2 21-inch submerged torpedo tubes, 2-in. side
armor, 2-in. protective deck. Yarmouth, British (1912), 430 ft.
between perpendiculars, 48 ft. 6 ins. beam, mean draft 15 ft. 3 ins.,
Yarrow boilers, Curtis turbines 24,000 h. p., speed 26 knots, nor-
mal coal 750 tons, 8 6-in. guns, 4 3-pounders, 2 21-in. submerged
torpedo tubes, 2-in. protective deck.
Scouts. — These are seagoing high speed vessels for finding out
the position of an enemy's fleet. They are lightly built and the
guns carried are of small sizes. They have no armor and every-
thing has been subordinated to produce a fast seagoing vessel.
U. S. Chester (1905), 420 ft. water line, 47 ft. 1 in. beam, 16 ft.
9 in. draft, displacement 3,750 tons, 4 screws, turbines of total
16,000 h. p., speed 26 knots, bunkers 1,250 tons. Two 5-in. guns, 6
3-inch, 2 3-pounders, 2 21-in. torpedo tubes.
Gunboats. — Small light draft vessels for use on shallow rivers
and bays. Their displacement is seldom over 1,700 tons, and they
have a speed of around 14 knots. U. S. Paducah, 174 ft. water
line, 35 ft. beam, draft 13 ft. 6 ins., twin screw with a total of 1,000
h. p., speed 12.9 knots, coal normal 100 tons, maximum 236, dis-
placement 1,085 tons. Six 4-in. guns, 4 6-pounders, 2 1-pounders.
Torpedo Boats. — About 170 ft. long, 80 to 180 tons displacement,
lightly built, with a few small guns mounted, and carrying two
or more torpedo tubes. Have a speed of 28 knots or better, many
using oil fuel and being driven by turbines. Of recent years, owing
to the development of submarines, torpedo boats have been little
used for the purpose they were originally intended for, viz., dis-
charging torpedoes at larger war vessels and then running away.
As a class few are now being built. British torpedo boat (1906),
172 ft. long, 18 ft. beam, 5 ft. 3 ins. mean draft, Parsons turbines, 3
screws, total 3,750 h. p., speed 26 knots, Yarrow boilers, oil fuel,
normal 20 tons, 2 12-pounders, 3 18-in. deck torpedo tubes.
Torpedo Boat Destroyers. — Larger and more powerful than tor-
pedo boats, carrying heavier guns. Are primarily designed to de-
stroy torpedo boats, are seagoing, and have a large radius of action.
Many of the latest types use oil for fuel, and are driven by steam
turbines. Make good patrol boats and during the European War
proved of great value in destroying submarines; for on account of
their speed it is difficult for a submarine to escape when once sighted.
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250 HULL CONSTRUCTION
Geared turbines were installed in the U. S. torpedo "boat destroyer
Wadsworth, which went in commission in 1915. There are 4 ahead
turbines (Parsons) driving by gears, 2 shafts, while for going astern
there are two other turbines that revolve in a vacuum when the
destroyer is going astern. The Wadsworth made 33 knots on trial.
She is 310 ft. long on water line, 29 ft. 8 ins. beam, mean draft
9 ft. 4J^ ins., block coefficient .44, displacement 1,050 tons, turbine
17,500 s. h. p., high pressure turbine 2,495 revs, per min., low
pressure 1,509, geared down to 450, propellers 7 ft. 7% ins. dia.,
pitch 8 ft. 7]/2 ins., oil burned per knot at speed of 30.72 knots
507 lb., water per s. h. p., 11.19 lb., carries four 4-in. rapid fire guns
and four 21-in. twin torpedo tubes. Direct drive turbines are in-
stalled on many destroyers.
Submarines. — The war in Europe (1914-) has shown the damage
these craft can do. At first they were only experimental affairs, but
now they are seagoing, with a radius of operation of 3,000 to 8,000
miles or more, and speeds of 14 knots or better per hour when
running on the surface and 8 or more when submerged. When run-
ning on the surface they are driven by Diesel engines, and when
submerged, by storage batteries furnishing current to electric mo-
tors. Besides being armed with submerged torpedo tubes, the
latest types have guns, some one or two three-inch.
The hull may be either single or double. In the former the main
ballast tank? are located within a strong outer hull, which in sec-
tion is in the main part circular or nearly so, with elliptical sections
forward and aft. In the double hull there is a more or less complete,
strong, pressure-resisting internal hull, which is surrounded by an
external hull of lighter construction, the^greater part of the water
ballast being in the space between the two hulls. The single hull
is represented by the Holland and Lake types as in the United
States, British, and German navies, and the double hull by the
Laubeuf . Horizontal rudders are usually fitted at the bow and stern,
and are sometimes combined with one or more sets of inclining
planes. In submerging the bow is always slightly depressed. The
reserve buoyancy varies from 25 to 40%.
Of the types in the United States Navy are the Holland (built
by the Electric Boat Co.) and the Lake (built by the Lake Sub-
marine Boat Co.). In the former the hull proper is circular in cross
section, on the top of which is built a superstructure, the water
being allowed to enter and leave it of its own accord, and having
nothing to do with the trimming. The superstructure is a con-
ioogle
SUBMARINES
Submarines
251
Particulars
U.S.
K
Class
Eng-
lish
D
French
Bru-
maire
U. S.i
Eng-
lish
E
German
U-33 ,
to
U-42
Length ,
Surface displacement, tons ....
Submerged displacement, tons.
Engines
Horse power, surface
Speed, surface, knots
Speed, submerged, knots
Armament, torpedo tubes ....
Armament, guns
153' 4*
389
519
Diesel
900
14 *
10^ '
4
150'
550
615
Diesel
1200
14
8-9»
3
400
550
Diesel
850
$
1
230' 6*
663'
912
Diesel
2000
17
10H
8 .
175'
730
825
Diesel
1600
15-16
9-10
6>
2
223'
665
822
Diesel
2300
17
10
5*
2
1 A late design of the Electric Boat Co. * Doubtful. From paper by L. Y. Spear,
published in Trans. Am. Soc. of N. A., 1915.
venient means for handling the submarine when coming alongside
a pier. There is a common tank at the lower part along the keel
into which the various tanks drain, and from this common tank
the water is discharged should the submarine desire to come to the
surface. In some instances the water is pumped out and in others
forced out by compressed air, the latter being the quickest but most
expensive. With all deck fittings fast it takes about 2>£ minutes
for a submarine to get under the surface traveling at J£ speed.
# The crew depend for air for breathing while submerged on the
free air in the submarine at the time of submerging and on the
compressed air carried in the storage flasks, which is used in freeing
ballast tanks of water as well as for breathing. In the average
submarine at the present writing (1917) the air contained at the
time of submerging is sufficient to last the officers and crew
numbering say 18 men, from 9 to 12 hours. If the air from the
storage flasks is used^— the time may be increased from 30 to 36
hours. In computing the time, the safe C 02 (carbon dioxide) that
should be allowed to accumulate in the air at any time is taken at
2 per cent.
In general there are 2 or 3 pairs of rudders, the vertical ones for
steering to port or starboard, and the horizontal ones for diving
and rising, assisted by fins forward. In sinking the horizontal rud-
ders are deflected when under way, water also being taken into the
tanks. To come to the surface the horizontal rudders are inclined
and the water is blown out of the tanks by compressed air.
In the latest Holland types (1916) there are fins on each side
forward, that are extended when a torpedo is fired, tending to keep
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252 HULL CONSTRUCTION
the submarine on an even keel. Forward there are 5 separate
tubes from which 'the torpedoes can be discharged. Over the ends
of the tubes fits a cap that revolves so that a torpedo can be dis-
charged from any tube.
The Lake submarine has a single hull, with tanks along the keel
and also on both sides at the top, the top plating of the tanks thus
forming a flat deck. There are 4 fins, 2 on each side forward and
the same number aft for steadying when discharging a torpedo and
keeping the submarine on a level keel. On some there is a small
vertical rudder aft extending above the deck, besides the one aft
of the propeller.
When running below the surface, by means of a periscope ex-
tending above the water the positions of other vessels are reflected
so they can be seen by the navigator of the submarine. One of the
latest models consists of a tube with lenses and at the bottom a
binocular eye-piece into which the navigator looks. The periscope
is only for daylight navigation, for when dusk comes it is useless.
The passing of the image through the various lenses and prisms re-
duces the brilliancy to such an extent that even if it is magnified
to above normal the image is so thin it cannot be seen. This forces
the submarine to become vulnerable in making an attack at night,
as it is necessary for the conning tower to be brought a sufficient
distance above the surface of the water for the commanding officer
to secure natural vision.
Recent practice is towards building two classes of submarines;
one about 100 feet or so in length, with a comparatively small
radius of action, for harbor defense only, and the other of 200 to
300 feet, that can proceed to sea with the fleet and only have to
return at long intervals to the home port.
Submarine Chasers. — These are small seagoing high speed boats,
carrying 2 or more small guns, and are primarily designed to harass
and destroy submarines. On account of their size and ability to
maneuver quickly they are difficult to hit with a torpedo, and with
their speed they can follow the wake of a submarine when one is
running submerged, and should the submarine attempt to come to
the surface the chaser opens fire on her.
Several were built in the United States in 1915, and below *are
particulars of one of ten for the Russian Government. Sixty ft.
long, 10 ft. beam, 2 ft. 10 ins. draft, V-bottom construction with
the floors flattened aft, oak frames, one-inch cedar planking, 4 steel
watertight bulkheads, 3 gasoline (petrol) motors each of 175 h. p.;
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STRUCTURAL DETAILS 253
guaranteed speed 26.1 miles per hour, actually made 28, fuel carried
in four 270-gallon tanks, total 1080 gallons, cruising radius at 26
miles an hour 500 to 600 miles, accommodations for 6 men and 2
officers; has 2 rudders, steel deck house forward for pilot, 2 small
guns. The United States authorized the building of several in 1917,
110 ft. long.
Auxiliaries. — These include colliers, repair ships, supply ships,
and tenders for submarines. They do not carry heavy guns, but
may have a few small ones to repel torpedo boat and submarine
attacks. Many are converted merchant vessels, while others are
specially designed for the service in which they are to be used.
STRUCTURAL DETAILS
Systems of Construction. — There are two systems for merchant
vessels, viz., the transverse as shown in Fig. 39, following Lloyd's
or other societies' rules, and the longitudinal or Isherwood as in
Fig. 40. The former has a large number of comparatively small
frames closely spaced, connected by brackets to beams thus forming
a complete section. Broadly speaking these transverse sections
are the fundamental strength members, but to obtain the requisite
fore and aft strength, keelsons, longitudinals, and stringers are neces-
sary. See paragraphs on these subjects as also on Frames. The
transverse system has been universally adopted, although for oil
carriers and steamers for grain and coal the longitudinal has been
used mostly in late years.
In the longitudinal or Isherwood system the transverse frames
and beams are at widely spaced intervals, the average distance
being about 12 ft. These heavy frames form complete belts around
the ship. They are riveted to the shell plating and deck, and arc
made of not less strength than the number of transverse frames
that are fitted in ordinary vessels for corresponding length of ship.
These strong frames are slotted around their outer edges to admit
of continuous longitudinal stiffeners or frames being fitted not only
at the deck but on the sides, bottom, and under the tank top.
The longitudinal stiffeners, being riveted to the deck plating,
prevent the plating from buckling, which has happened to transverse
framed vessels having no fore and aft support to the plating be-
tween the beams. In vessels with double bottoms, transverse floor
plates are fitted intermediate to those at the sides and decks. Bulb
angles can be used as longitudinals under the tank top and on the
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Figure 39. — Transverse System.
254
. FRAMING 255
inside of the shell plating, thereby providing a double bottom which
is easier of access than one built on the transverse system. See
Fig. 40.
In the Isherwood system the inner bottom may extend to the skin
of the ship whereas in a transverse framed ship it usually stops just
before the lower turn of the bilge, leaving a space that is of no value for
carrying cargo. Among the advantages claimed by the Isherwood
system are increased longitudinal strength, increased deadweight
carrying capacity, holds free from small pillars, and a reduction in
the shell plating due to the increased longitudinal strength obtained
by the fore and aft members.
The location and number of the bulkheads are the same irre-
spective of the system of construction. In the following paragraphs,
excepting frames, keelsons, and those relating to transverse framing,
the others, as shell plating, bulkheads, etc., in general apply to
the longitudinal as well as to the transverse system.
Framing. — Until recent years iron and steel merchant vessels
were framed on the transverse system, but in certain types, as bulk
cargo and oil tankers, this has been replaced by the longitudinal or
Isherwood system. The frames of a transverse framed steel ship
vary in size and spacing according to the rules, viz., Lloyd's, Amer-
ican Bureau of Shipping, or other society, to which she is built.
In Lloyd's rules the frames depend on the transverse number,
B + D, which is the sum of the molded breadth B and the molded
depth D, which is the depth at mid-length from top of keel to top
of uppermost continuous deck, except in awning and shelter deck
vessels, where it is taken to the deck next below the shelter deck '
provided the deck height does not exceed 8 ft., in which case it is
taken to a point 8 ft. below the shelter deck. A second depth d has
also to be considered in getting the size of the frames, this depth
being measured from the top of the floors at the center in a single
bottom ship, and from the margin plate at the side in a double
bottom ship, to the top of the beams of the lowest laid deck or tier
of beams at the side.
The frames vary in size from 2J4 X 2J4 angles to 12 X 4 X 4
channels, and in spacing from 20 to 33 ins. from heel to heel, while
in peak tanks 24 ins., and one-fifth of the length forward to the
collision bulkhead the spacing is not to exceed 27 ins.
The framing of a single bottom ship consists of a frame, reverse
frame, and floor plate. The frame in this case usually extends in
one length from the center line to the top deck. In deep framing
Digitized by vjOOQ 1C
256 HULL CONSTRUCTION
it is common practice to place a small angle at the lower edge of the
floor plate overlapping the larger side frame at the bilge, and thus
save weight. In most merchant vessels deep frames are used in
conjunction with side stringers formed of plate and angle, thus
giving a clear hold with unbroken stowage. These deep frames may
be formed of two angles riveted together, but the more common
is the equivalent bulb angle or channel section. Web frames and
side stringers with small intermediate frames can also be used, but
this construction is not much in favor on account of the interference
with the cargo.
The toes of all frames forward of the midship section point aft,
while those aft of the midship section have the heels aft and the
toes forward. This gives open bevels and thus room for driving
the rivets connecting the frames to the shell plating. The frames
are in some instances joggled, in which case no liners are required
even if the plating is worked in and out. In fact it is usual
to joggle the frames for about three-fifths of the length amid-
ships when they are not more than 10 ins. deep and thus save
the weight of the frame liners. This makes a better job than
joggling the plating which is apt to leak and work in a seaway.
Joggled frames can be employed to advantage in the Isherwood
system, as they are in rather short pieces, one template doing for
a large number, the joggling being done cold.
Reverse frames extend from bilge to bilge doubled in engine and
boiler rooms; where the framing is built up of frame and reverse
frame they run up the frame above the bilge, depending on the depth
d (see above).
The depth of the floor plates at the center line is governed by the
same transverse number used for the frames. The floor plates are
to be molded not less than one-half their depth at a point three-
fourths the half-breadth of the vessel from the center line and to
extend up the bilge in a fair curve terminating at a point on the
frame not less than twice their midship depth at center line, this
height to be maintained for one-fourth the vessel's length amid-
ships; they may then be gradually lowered forward and aft until
the upper edges are level; depending on the shape of the Vessel
from this point to the ends they may be gradually increased in
depth to give better connection. In the engine room the floors
must be increased .04 in. over the midship thickness and in the
boiler room .10 in.
The above applies in general to vessels without double bottoms.
Digitized by VJiOOQ 1C
FRAMING
257
Double bottoms are usually built on the cellular system with solid
floors either at every frame or on alternate frames, or other con-
struction followed subject to the approval of the society to whose
rules the vessel is being built. See also Double Bottom.
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Figure 40. — Longitudinal or Isherwood System.
Frames usually extend in one piece from the center line to the
margin plate and if floors are on alternate frames heavier scantlings
Digitized by VjiOOQ 1C
258 HULL CONSTRUCTION
are required for the intermediate frames. When the vessel's length
exceeds 400 ft. solid floors are required at every frame* and also
in single deck vessels which exceed 26 ft. molded depth.
Reverse frames are generally in one length from the center line
to the margin plate and doubled in the engine room to the girder
or longitudinal next beyond the engine seating and under the
boiler bearers. In double bottoms with floors at alternate frames
the alternate rsverse frames may be dispensed with provided the
inner bottom plating be increased .04 in. in thickness. In the
boiler room the floors are increased .10 in. When floors are on
alternate frames bracket plates are to be fitted on alternate frames
at the center line and at the margin plate, and additional girders
are to be fitted under the engine seating.
A reduction in the thickness of the shell plating is allowed when
solid floors are on every frame, provided the thickness does not
exceed .66 in.
Shell Plating. — The shell plating may be worked as, in and out
"strakes, joggled, clinker, or flush as shown in Fig. 41. In and
out strakes are largely adopted, the keel, bilge, and sheer strakes
being made outside strakes for ease of removal in case of damage.
When a vessel is so plated parallel liners are required between
the frames and' the out strakes. If the plating is joggled no liners
are necessary, while in the clinker only tapered liners are needed.
Flush plating calls for extensive linering and is chiefly for yachts
for appearance' sake, as the liners materially add to the weight of
the hull.
The widths of the plates selected should be as near as possible
the same for all the strakes, thus making the plates interchange-
able. The following table gives the maximum width of the shell
plates according to Lloyd's rules.
Depth of Vessel in Feet
Maximum Breadth of
Strake Plating in Inches
Not exceeding 20
54
Above 20, not exceeding 24
60
Above 24, not exceeding 28
66
Above 28
72
The widths are laid off on the midship frame of the body plan
(one-half fore body and the other after body), and the plate lines
sketched in, keeping the lines or sight edges parallel amidships
nvJ^Vl^
1
SHELL PLATING
259
and tapered slightly at the ends above the water line, thus requir-
ing as the stem and stern are approached the working in of stealers
in the lower strakes, one stealer taking the place of two or more
5s
X\
=S^ \
^ / —
ti
frame j
*•»
*
Figure 41.— Shell Plating.
Digiti
zed by G00gk
260 HULL CONSTRUCTION
narrow strakes of plating. In the after body the plating between
the oxter and sheer strake is divided into the same number of
strakes and lines run in, stealers being employed where necessary.
By so dividing the strakes, all the difficult work may be in one
plate, that is, in the oxter, instead of in several. The above pro-
cedure is followed in laying out the plating for a single screw vessel.
In a twin, triple or quadruple screw the forebody is worked the
same as for a single, but in the after body care must be taken in
laying out the plating around the shaft tubes so the plates may be
easily worked, short plates being selected for furnacing.
Coincident with the laying out of the shell plating on the body
plan and the making of a drawing of the shell expansion, a model
is made. In large vessels the plates may be 24 to 28 ft. in length,
but care must be taken in selecting a length that can be easily
handled. In ordering shell plates it is usual to take the widths
from the mold loft and only the lengths from the model as this
gives less scrap.
The thickness of the plating, sizes of laps and butts are given
in the rules of the classification societies. In Lloyd's there is
now no garboard strake except in the case of a vessel with a bar
keel. Bottom and bilge plating all have the same thickness. In
some large vessels the sheer strake is doubled for half the length
amidships. The thickness of all the strakes is greatest amidships
and is gradually reduced at the ends, although doubling plates are
required around cargo ports, hawse pipes and other parts subject
to excessive local stresses. When lap butts are selected the laps
should face aft, so that when the vessel is moving alongside a pier
no projecting parts will catch; and furthermore there is no resist-
ance offered by them when the ship is moving through the water.
In laying out the shell plating a good shift of butts should be
secured and they must not come* in the same frame space as those
of the keel, tank top plating, longitudinals or deck stringers.
Lloyd's rules state: no butts of outside plating in adjoining strakes
to be nearer each other than two frame spaces, and the butts of
alternate strakes must not be under each other, but shifted not
less than one frame space. The sheer strake must extend suffi-
ciently above the* upper deck ends to take at least two rows of
rivets vertically in the butts above the upper flange of the gunwale
bar.
All shell plates are flush riveted with perhaps the single exception
of the sheer strake in large vessels where there are doubling plates,
Digitized by VJiOOQ LC
BULWARKS « 261
in which case the riveting may be done by machine, the rivets
being given button points. In fitting doubling plates tack rivets
are driven along the edges as also in the middle portions of the plates.
Lloyd's requires all flush butts of plating to be planed and fitted
close, all overlapped butts and edges to be sheared from the faying
surfaces, or the burr caused by shearing to be carefully chipped
off, and all outside edges of seams and lapped butts to be either
planed or chipped fair. The rivet holes are to be punched from
the faying surfaces, opposite each other in the adjoining parts,
laps, lining pieces, buttstraps and frames.
In the garboard strake or the strake next to the keel brass plugs'
are sometimes fitted, by unscrewing which when in dry dock the
inner bottom compartments may be drained.
Bulwarks. — These are sometimes fitted forward to keep the
water off the deck, or in the wells of large vessels, or on bridge or
promenade decks. The plating is usually light of about 12.5 lb.
and may be supported by wrought iron stanchions, by flanged
plates or by bulb angles, spaced not more than 6 -ft. apart, and the
top finished off with a bulb angle or channel. Teak rails are only
fitted on passenger steamers and then very rarely on account of
the cost. In the bulwarks are openings called freeing ports for the
water to run off the deck, and also openings through which the
lines for handling the vessel can pass.
Double or Inner Bottom. — This is important as it serves not
only to prevent water from entering the ship should the shell plat-
ing be pierced, but also provides a means for carrying water ballast.
or oil fuel. It extends approximately from bilge to bilge, and
as far forward and aft as practical. The frames and reverse frames
are usually joggled in a double bottom as they are smaller than the
main frames which are connected by brackets to the margin plate,
the margin plate being near the turn of tha bilge. See Fig. 39.
The breadth of the bracket at the ship's side and its rivet attach-
ment to the frame angle must in no case be less than its breadth
and attachment at the margin plate. At the lower edge of the
margin plate is a continuous angle riveted to the shell, while the
upper part of the plate is flange4 over, generally inboard, and riveted
to the inner bottom plating (tank top). A gusset plate is riveted
over the flange of the margin plate and also to the reverse angle
of the vertical frame, depending on the size of the ship. If the ship
is large enough to have gussets at every frame it is usual to carry
Digitized by VjiOOQIC
262
HULL CONSTRUCTION
the double bottom plating over on the margin brackets and an angle
is fitted at both the top and bottom of the margin plate.
Instead of the above construction the tank top may extend
to the shell plating with an angle connection, and be flanged con-
nected thereto at the ends. A flanged plate is employed at the
ends on account of the difficulty of riveting an angle to the shell
and tank top. The frame bracket is riveted to the top of the
tank top, but this construction interferes with the stowage of
cargo and is not adopted as extensively as the one outlined in the
previous paragraph.
The thickness of the plating is specified by the rules. Under
the boilers it is increased in thickness. The seams run fore and
aft, and care must be taken to secure a good shift of butts that
will not coincide with those of the shell, center keelson and longi-
tudinals. The plating may be either alternately in and out or
one edge in and the other out.
When a double bottom extends through the engine and boiler
spaces, a well should be formed between the after engine room
bulkhead and the floor immediately forward of it for drainage
purposes, or open gutterways of sufficient size should be made in
the wings so as always to be accessible. To give* access to the
floors and longitudinals manholes are fitted in the tank top; these
manholes may be plates bolted to the plating or they may have
hinged covers that can be bolted down.
/Yoor
Kee/&os? cy/?^/es
e//>/ece
Figure 42. — Bar Keel.
Where the side girders are spaced more than 6 tt. apart the
watertight floors in double bottoms are to be stiffened by vertical
Digitized by VjiOOQIC
AIR PIPES, THE TANK TOP, ETC. 263
angles of the size of the frame angle on the floor, spaced midway
between the girders. Every floor in the engine space should have
double reverse angles, as also on each floor in way of boiler bearers.
They are to extend in all cases from the middle line to beyond
the girder next outside the engine seating.
Air pipes should be fitted in sufficient number and size and
wherever necessary, one being at each end of each tank on both
sides of the vessel.
The tank top may be covered with a bituminous compound instead
of a wood ceiling (see Carpenter Work), the former having the advan-
tage of well protecting the plating when properly applied.
Keelsons and Longitudinals or Side Girders. — In a vessel without
a double bottom there is a fore and aft center plate with angles
at the top and bottom, called the center keelson, and between it
and the turn of the bilge, one or more plates with angles called side
keelsons, and at the bilge another of similar construction called
a bilge keelson. These same members in a vessel with a double
bottom are often given the names of center girder and side girders
or longitudinals, which in the latter case are numbered as first
longitudinal, second, and so on.
The center girder is continuous fore and aft and is riveted to the
tank top and to the keel, and also to the stem and stern post. It
is usually watertight but not necessarily caulked, although the rivets
may be given a watertight spacing. In the way of tanks it is
caulked. Lloyd's recommend "that keelsons be carried fore and
aft continuously through bulkheads, the latter being made water-
tight around them. Side and bilge keelsons are fitted with inter-
costal plates attached to the shell plating by angles as may be
required. All angle and bulb angle bars of keelsons are to be in
long lengths, properly shifted and wherever butted to be connected
with angles not less than 2 ft. long fitted in the throat of them,
properly riveted to each flange." See section on Oil Carriers.
Longitudinals are intercostal in some vessels between the frames,
while in others, as in battleships, they are continuous, the frames
being cut. They have lightening holes, but in large vessels with
several longitudinals one or more of them are made watertight.
Wherever possible they should be arranged so that in the engine
room they form part of the engine foundation. They should not
be stopped abruptly, but be gradually reduced in size beyond ths
distance they are called on to extend by the rules.
Digitized by VjiOOQIC
264
HULL CONSTRUCTION
Instead of running the keelsons continuously through the bulk-
heads they may be stopped and bracketed to them.
Keels. — Figs. 42 and 43 show different types. Flat plate keels for
large vessels, while for tugs, lighters and other small craft, bar keels.
With flat plate keels intercostal keelson plates or vertical center
plates must be fitted close down on the keel plate and connected to
£65 ' Sf earner
Figure 43.— Plate Keel.
it by double angles riveted all fore and aft to the keel plate and
keelson. Bar keels should be worked in long lengths, connected
together by rigfft and left hand scarphs that are generally nine
times the thickness of the bar in length.
Bilge keels may be of a single bulb angle or of a plate and
angle, or bulb plate and T bar or plates arranged with a V-cross
section packed with wood and riveted to angles that in turn are
riveted to the shell. Bilge keels are to prevent excessive rolling and
extend about two-thirds or less of the length of the vessel; they
should be carefully located so as not to retard the speed. A 160-ft.
steamer had fitted bilge keels consisting of a 5-in. X 4^in. X 15-lb.
T bar to which was riveted a 10-in. X H-in. bulb plate. In large
vessels the keels may be 24 ins. or more in width.
Docking Keels.— Only installed on war vessels; consist of a
fore and aft timber about 12 ins. wide by 6 ins. thick, connected
to the shell plating by angles. The keels should be placed under
longitudinals so when the vessel rests on them in dry dock the shell
plating will be well supported. They extend a little over one-
half the length of the vessel.
Deck Plating and Coverings. — The plating is riveted to the deck
beams and is laid with alternate in and out strakes, or one edge of a
Digitized by VjOOQLC
DECK PLATING 265
strake in and the other out, or the plating may be flush or joggled.
When the plating is not to be covered the strakes may be arranged
in and out so that water on the deck will flow towards the water-
ways, and thence through the scuppers and overboard. Flush decks
made by joggling down the beams and fitting joggled plating are
much cheaper than flush decks with planed and fitted edge laps,
equally efficient for trucking, and better from the riveting and
structural point of view. Strake next to the shell; that is the
stringer is heavier than the others. The plates are ordered in long
lengths, the seams running fore and aft, the sizes of laps and butt-
straps are given by the rules (Lloyd's, American Bureau of Shipping,
etc.). All the riveting has watertight spacing and the plate edges
caulked.
The deck plating is invariably continuous, the bulkheads being
intercostal (see Bulkheads). When the frames extend through a
watertight deck, stapling may be worked between the frames and
riveted to them as well as to the deck and shell plating, after which
the stapling is caulked. Or, as more usually the case, the frames
are cut and bracketed to the watertight deck or flat.
Deck planking (see Carpenter and Joiner Work).
When vertical donkey boilers are placed on a steel deck, the
deck underneath them is to be covered with fire brick or cement
not less than 2 ins. thick. The deck on which fires may be drawn
from a donkey boiler is also to be protected by fire brick or cement
not less than 2 ins. thick.
In the galley, toilets, bathrooms, and where it is necessary to
flush the floors frequently, other material than wood is laid for
covering the steel deck.. In some instances linoleum, it being
fastened down by cement or by metal strips bolted to the deck.
In the toilets and bathrooms either rubber or clay tiling embedded
in cement or an asphalt flooring may be laid.
Deck beams are connected to the frames by knees or brackets
which are in accordance with Lloyd's or other societies' rules. The
beams on the upper decks are given a camber of about ]/i of an inch
to the foot in the ship's width. Those on the lower decks and in
the holds are often straight.
Beams are to be fitted at every frame:
(a) At all watertight flats;
(b) At upper decks of single deck vessels above 15 ft. in depth;
(c) At unsheathed upper decks when a complete steel deck is
Digitized by VJiOOQ 1C
266 HULL CONSTRUCTION
required by the rules, also at unsheathed bridge decks,
awning or shelter decks. In vessels over 450 ft. in length
the beams of the upper, awning or shelter decks are to be
fitted at every frame whether the plating is sheathed or
not. Upper decks in way of poops, forecastles and bridges
of vessels not exceeding 66 ft. in breadth may have the
beams fitted at alternate frames except for one-tenth the
vessel's length within each end of the bridge where they
are to be fitted at every frame;
(d) Where no wood deck is laid on a steel or iron deck (required
by the rules) at sides of hatchways including those of engine
and boiler room openings.
Elsewhere deck beams must in no case be spaced more than two
frame spaces apart and only when the frame spacing does not ex-
ceed 27 ins. (Lloyd's requirements).
When it is intended to suspend chilled beef or similar products
from the beams, the beams and the girders under them must be
of extra strength. Strong beams in the machinery space are to
have double angles on their upper and lower edges unless cross tie
plating is fitted on them, in which case only single angles are re-
quired on the upper and lower edges.
Single deck vessels can be built according to Lloyd's without
any intermediate hold beams; in fact the rules cover single deckers
up to 31 ft. in depth.
Hatchways. — Beams forming the end of hatchways above 10 ft.
in length where beams are at every frame are to be not less than the
size required for beams at alternate frames. To the deck are
riveted angles which are riveted to coaming plates. The thickness
of these plates is according to Lloyd's or other societies' rules and the
angles connecting same are to be the same thickness as the plates
and welded at the corners.
Side coamings are to extend below the beams and be flanged
for a breadth of 6 ins. under the half-beams when hatches exceed
10 ft. in length, and also are stiffened near the top by horizontal
bulb angles not less than 7 ins. in depth or their equivalent. The
athwartship plates may be worked with an incline or pitch, the
highest part being at the center, and they are not given the camber
of the deck beam as the hatch covers will fit better without it.
See Hatch Covers.
Digitized by LiOOQ IC
HATCH OPENINGS
267
&&#&/?//?$ c/eafs /7o?
fa fa Ate 6ajfe/?//?p
Strips &/•?<* tvecf&es m
p
&e<r/7? every y
Figure 44. — Section Through Hatch Coaming.
Height of Coamings. — On upper, awning or raised quarter deck
exposed 24 ins.
On decks of superstructures other than awning decks, where
exposed to the weather, within one-quarter length from the
stem 24 ins., when aft of one-quarter length, 18 ins.
On decks inside superstructures, the openings in the latter
having no means of closing, 18 ins.
On decks inside superstructures the openings in the latter
being closed by strong wood doors or shifting boards fitted in
channels, 9 ins.
On decks below the upper or awning decks or within an
intact superstructure the coaming plates need not extend
above the deck, but in such cases an angle coaming should
be fitted around these hatchways.
Hatch openings should have round corners on weather decks
and on the top of the coaming plate have riveted either a special
rolled section (see Fig. 44), or a Z bar. On the outside are cleats
spaced about 9 ins. from the corners and 2 ft. apart, and at such
a distance from the top that the tarpaulin cover can be easily
Digitized by vjOOQ 1C
r
268 HULL CONSTRUCTION
fitted when the battening bar, say 2\4 his. X XA in., is placed in
position. On the sides are two or three lashing rings.
On large hatches heavy portable fore and afters and beams
are fitted (maximum spacing 4 ft. 6 ins.) to support the covers
efficiently.
Pillars or stanchions are of wrought iron pipe or of plates and
angles extending from the beams of one deck to the plating of the
one below. In vessels with several decks or tiers of beams, in
order that the stanchions develop their full efficiency they should
extend from the center keelson or tank top to the upper deck as
nearly as possible in a vertical line so as to form a continuous tie,
the upper stanchions being fighter than those in the hold.
It is now the practice in cargo steamers to have large stanchions
widely spaced; a single row for vessels up to and not exceeding
44 ft. beam, double row from 44 ft. to 50 ft. and three rows above
50 ft., which may support fore and aft girders fastened to the
under side of the deck and to the deck beams. With this arrange-
ment holds are obtained that are free from a number of small
pillars. An example of a girder and pillar is shown in Fig. 45.
Stringers. — These are continuous angles on the inside of the
frames, and when the frames exceed a certain depth, Lloyd's re-
quires intercostal plates to be fitted, attached to the shell plating
by angles of the thickness of the intercostal plates. The stringer
angles are attached to each reverse frame or to angle lugs on the
frames with at least two rivets, and connected by brackets to the
transverse watertight bulkheads. They should be perpendicular to
the shell, thus giving the maximum support to it. The outboard
angles should be worked straight without any bevel. When the
stringers are 18 ins. in width or over, Lloyd's requires bracket plates
to be fitted below them, except, however, should the web frames
in the vessel be spaced 8 ft. apart.
Panting stringers consist of plates and angles similar to side
stringers and are located forward to stiffen the frames and shell
plating, as the comparatively fiat surfaces of the plating have a
tendency to pant, that is, move in and out in a seaway. The
panting stringers from both sides are connected at the stem to a
common plate called a breasthook.
Bulkheads. — The number and height of watertight bulkheads
are fixed by the rules (in Great Britain by the Board of Trade)
under which the vessel will be built. Watertight transverse bulk-
heads are of value as they give structural strength, prevent fires
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BULKHEADS
269
C///9 Ad ofccA
/ rWcrte prefer s&ecA
a/ p///crr
Spec/a/ afS/ffe/tt/Ty
<//></er p///ar/br
2 frcr/7?e spaces
L oppeefp/crfe
arp/pe c/epe/ttf/Tp
o/j s/ze
t-oca/ cfoi/6/er
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Figure 45.— Hold Pillar.
from spreading, and also prevent water from flowing into other
compartments should one compartment be flooded. Longitudinal
bulkheads are valuable structurally as they form a vertical web,
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270
HULL CONSTRUCTION
thus adding greatly to the fore and aft strength of a vessel. Battle-
ships, tankers and large passenger vessels have suqh bulkheads.
Lloyd's states: "Screw steamers are to have a watertight bulk-
head at each end of the engine and boiler space. A watertight
collision bulkhead is in addition to be fitted at not less than 5%
of the vessel's length abaft the fore part of the stem measured at
the fore part of the stem at the load waterline and a watertight
bulkhead is also to be fitted at a reasonable distance from the
after end of the vessel.
"The foremost or collision bulkhead is to extend from the floor
plates to the upper, awning or shelter deck and its watertightness
is to be tested by filling the peak with water to the height of the
load line.
"In vessels above 285 ft. and not exceeding 335 ft., an additional
bulkhead is to be fitted in the main hold about midway between
the collision and boiler room bulkheads.
"In vessels above 335 ft. and not exceeding 405 ft. two additional
watertight bulkheads are to be fitted one in the fore hold and one
in the after hold.
Vessels Above
And Not Exceeding
Additional Watertight Bulk-
heads to be Fitted
405 ft.
470 "
540 "
610 •"
470 ft.
540 "
610 "
680 "
3
4
5
6
"Where the machinery is fitted aft in vessels above 220 ft. and
not exceeding 285 ft., a watertight bulkhead is to be fitted about
midway between the collision bulkhead and the bulkhead at the
fore end of the engine and boiler space.
"The bulkheads are to extend to the height of the upper deck
except in awning or shelter deck vessels in which cases the bulk-
heads with the exception of the collision, may extend to the deck
next below the awning or shelter deck. In awning or shelter deck
vessels with a continuous superstructure or bridge house a deep
web frame or partial bulkhead is to be fitted on each side in the
'tween-decks over each of the watertight bulkheads which extend
only to the deck next below the awning or shelter deck. Partial
bulkheads may be dispensed with if other efficient strengthening
is provided to the satisfaction of the Committee. The after col-
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THICKNESS OF THE PLATING 271
lision bulkhead may extend to the first deck above the load line
subject to the approval of the Committee, provided this deck
forms a watertight flat from the bulkhead to the stern, otherwise
it must extend to the upper deck."
American Bureau of Shipping states: "All vessels must have a
forward watertight collision bulkhead extending to the upper and
to second deck in hurricane deck vessels. As to the after collision
bulkhead this is to extend to the upper deck, second deck in hurri-
cane and three deck vessels and have a watertight steel flat extend-
ing aft from it to the stern post so as to form a watertight com-
partment around the stern tube for the screw shaft."
The Bulkhead Committee of the British Board of Trade issued
a report in 1915 requiring that all vessels carrying 12 passengers
or over must be subdivided according to definite standards. The
most important factor regulating the subdivision is the freeboard
ratio or the ratio of freeboard to draft. If this is small, the surplus
buoyancy of a vessel is small and the spacing of the bulkheads is
close. If large holds are required the freeboard ratio must be
considerable, which may be obtained by either limiting the draft
or increasing the depth. In some cases the bulkheads are carried
to a deck higher than what would otherwise be the bulkhead deck.
The plating of transverse as also longitudinal bulkheads is
invariably worked intercostal between the decks. In transverse,
the plating may be either in vertical or horizontal strakes, or a
combination of the two. By using a vertical plate on each side at
the shell, the others may be rectangular with the seams horizontal
if desired. The side plates are connected to the shell by single or
double angles as called for by the rules, and the upper plates to
the deck by single or double angles. As the holes caused by the
riveting of two angles to the shell weaken the shell, this is strength-
ened by adding doubling plates or liners. Lloyd's states that
doubling plates between frames and outside plating in way of bulk-
heads are to extend in one piece from the foreside of the frame
before to the afterside of the frame abaft the bulkhead frames, or
they may be of an approved diamond shape. These doubling plates
may be dispensed with provided the transverse watertight bulk-
heads are connected to the sides of the vessel by brackets, fitted
at each side stringer and hold stringer.
The thickness of the plating varies, the lightest being at top.
The plating is stiffened by vertical stiffeners bracketed in some
instances to the deck, and to the tank top as may be required by
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272 HULL CONSTRUCTION
the rules, which also give the thickness of the plating and the
riveting. Vertical stiffeners are the only ones (except in tankers
which also have horizontal stiffeners) 'required by Lloyd's in accord-
ance with the tables issued in May, 1915. In torpedo boats and
in other high speed vessels, instead of vertical stiffeners the plates
are sometimes flanged, thus saving weight.
To secure waterti^htness bulkheads must > be caulked, and this
is usually done on the after side of bulkheads forward of amid-
ships, and on the forward side of those aft. The stiffeners are
arranged so they do not come on the side to be caulked. As
a rule it is necessary to caulk only one side of a bulkhead. In
tankers the greatest care must be exercised to get oil tightness, not
only by spacing the rivets closer but by additional care in caulk-
ing. See section in Oil Carriers.
Stopwaters. — These consist of packing pieces or liners applied
locally. They are fitted when the caulking edge is inaccessible,
as in a watertight bulkhead when stiffeners are placed on the caulk-
ing side crossing the seams of plating. Stopwaters may be of
canvas, burlap, or felt soaked in red lead, in tar, or a mixture of
red lead and tar. One of the best materials is hempfelt sheeting
soaked in tar.
Stem and stern frames may be of cast steel or of forgings. In
large vessels they are in two or more parts riveted together. Their
sizes are specified in the rules, Lloyd's, American Bureau of Ship-
ping, etc. In bar keel vessels the lower part of the stem is of the
same molding as the keel and is fastened to it by a scarph of the
same length as the keel scarph (see Keels). In flat keel vessels the
center keelson extends well forward and is riveted to the stem
when possible and in addition the angles on each side of the center
keelson extend as far forward as practical and are riveted to the
stem as well as to the flat keel.
The stern frame consists of two posts, the forward or body post
and the after or stern post, that are connected at the bottom by a
flattened portion, and at the top by an arched. In vessels whose
longitudinal number (Lloyd's) is over 16,000 the forward or pro-
peller post should extend sufficiently above the arch of the stern
post to be efficiently connected to the plating on the beams and
to a deep transom plate. In single and triple screw vessels the
body post is swelled out to take the stern tube. The spur or heel
for connecting to the keel (bar or flat) is usually 2lA frame spaces
long. The center keelson is connected as outlined for the stem.
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STERN TUBE 273
To the after or stern post are forged or cast (depending on whether
the post is a forging or a casting) gudgeons for the rudder pintles.
The upper gudgeon should be as near as is practical to the rudder
trunk, while the others are 4 ft. C ins. to 5 ft. apart. One of the
gudgeons in small vessels and two in large are shaped so as to* form
a hard-over stop for the rudder. At the bottom of the stern post
there may be a spur extending aft that takes the lower rudder
pintle. Gudgeons must not be less in depth than seven-tenths the
diameter of the rudder head, and the thickness one-half the diam-
eter of the pintles. The stern post must extend sufficiently above
the counter to be connected to the full depth of the transom plate.
Stern Tube. — This in a single screw vessel extends from the stern
post to the after collision bulkhead. The after end at the stern
4 post has a composition bushing with lignum vitae strips, with the
grain set perpendicular to the shaft. The shaft in the way of
the strips has a brass sleeve. At the collision bulkhead is a stuffing
box.
Propeller Struts. — These are usually of cast steel with an elliptical
cross section, the forward part having a larger radius than the
after. The center of the strut should be placed on a frame so as
to secure the maximum stiffness. In wake of the upper palm
doubling plates should be fitted on the shell plating, while the
lower palm should be riveted to the keel. Struts should be set so
as to conform to the run of the water, so the arms will not cross the
stream lines and interfere with the speed of the vessel.
Simpson's formula* for propeller struts is as follows:
R = revolutions of engines per minute
P — indicated horse power for one shaft only
I = outboard length of shaft from stern tube outer bearing to
center of boss in ins.
k = coefficient =» .0633 R
. , </R XPXl
Then area in squaro inches = -r
The proportions of the pear-shaped arm are:
Length = \/ 5.3 X area
Distance maximum breadth from the forward end = .33 X
length
Maximum breadth = .25 X length
Radius at forward end = .25 X maximum breadth
Radius at after end = .50 X radius at forward end.
*From The Naval Constructor, G. Simpson.
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274 HULL CONSTRUCTION
For the lesser powers and for brackets intended for wood of
composite vessels, the brackets should be of gun metal or bronze,
and for higher powers and steel ships of cast steel.
Spectacle Frames. — These have taken the place of propeller
struts in large twin and triple screw vessels. They are of cast
steel and their cross section may be calculated by the same formula
as for propeller struts and the result multiplied by two, as in this
case there is only one arm whereas in the other there are two. The
shell plating is worked completely around the frames, thus inclosing
the propeller shaft. Additional strength must be obtained in
wake of the spectacle frames by increasing the floors and doubling
the ship's frames.
Rudders may be of cast steel, or a steel plate riveted to wrought
iron arms, or a wrought iron frame packed with wood and then
covered with steel plates. Cast steel rudders, particularly if only
one is required, are expensive, while those packed with wood are
heavy. The most satisfactory is a single plate riveted to arms
on alternate sides, the plate varying from % to \x/i ins. in thick-
ness depending on the size of the vessel.
A quick formula for calculating the diameter of the rudder stock
is given in the British Corporation rules (see also Lloyd's, Amer-
ican Bureau of Shipping, etc.) as follows:
Let d = diameter of stock in ins.
A = area of rudder in sq. ft.
r = distance from center of gravity to axis in ft.
V = speed in knots
Then d = .26 \/ r A F*
The rudder stock may have a vertical or horizontal palm, which
is bolted to a corresponding one on the frame, a key being inserted,
or the parts may be scarphed together. The pintles should be
separate from the rudder frame and of a cone shape (see Fig. 46)
and one, called the locking pintle, must have a nut to prevent the
rudder from jumping in a seaway. To the rudder stock is keyed
either a tiller or a quadrant — if the steering engine is located
forward. If a tiller is selected it is necessary to have sheaves to
take up the slack rope, but if a quadrant no sheaves are necessary.
See Steering Engines.
The forward side of the rudder frame is made preferably in one
continuous line with the projections for the pintles forged or cast
on, as by so doing a strong frame is obtained. To nil in the spaces
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7bi*6oat
4
Passenger j Cargo Sf earner
State Wfree/ Stee/ner
RW
§
j3a/f/e Sh//>
Figure 46. — Rudders.
275
Digiti
zed by G00gk
276 HULL CONSTRUCTION
between the pintles, plates are riveted to the outside of the frame.
Rudders for sidcwheelers often have a bumpkin at the after part
to which the steering gear is attached. In this case the rudder is
turned by pulling on the bumpkin, the rudder post serving only as
a pivot.
As to shapes there is a variety as shown in Fig. 45. For tugs,
lighters and side-wheel steamers the maximum width is near the
load water line and the area is large. For ocean-going vessels the
area is smaller in proportion to their length and the maximum
width is about % from the load water line. The balanced rudder
is extensively used, particularly on warships. In this type a por-
tion of the area is forward of the rudder stock. The rudders of
warships are broader and shallower than those of merchant vessels
so as to keep them and the steering gear well below the water line.
Below are ratios of the areas of rudders to the areas of lateral or
longitudinal planes of different types of vessels.
Ratio of Area of Rudder to Area of Lateral Plane*
Type of Vessel
Unbalanced
Rudder
Compensated
Rudder
Paddle wheel
.021
.016
.020
.025
Large passenger
Ordinary screw
.024
Armored ships
•030
As an example take the U. S. fuel oil ship Cuyamaf 455 ft. long,
56 ft. beam, 35 ft. 9J^ ins. depth of hold, trial displacement 14,500
tons, speed loaded 14 knots, rudder of balanced type, area to 26 ft.
4 ins., water line 190 sq. ft. abaft of pintles and 35 sq. ft. forward
of pintles, total area 225 sq. ft., extreme working angle of rudder
from amidship to hard over,' 35°. Engine, two-cylinder, each 10
ins. dia. by 10 ins. stroke, steam 125 lb., can put rudder hard over
in 30 seconds when vessel is going full speed.
Where the rudder enters the counter there is a watertight trunk,
which should be of sufficient size so the rudder may be readily
unshipped. For appearance* sake and to prevent the constant
flowing in and out of the water, the lower part of the trunk is cov-
ered over by a bolted plate.
Suitable stops for the rudder should be securely fastened to the
deck in way of the tiller or quadrant. When the quadrant is geared
direct to the steam steering engine the deck stops may be dispensed
* From Naval Architecture, C. H. Peabody.
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MACHINERY FOUNDATIONS 277
with. The stops for the steering engine should be at a smaller
angle of helm than the rudder stops.
Machinery Foundations. — Foundations for the engines, boilers,
pumps, and auxiliary machinery should be well and strongly built.
Scotch boilers should be kept up high enough to allow a man to get
under them and also there should be room between them and t!:e
deck above to adjust safety valves and other boiler fittings. Care
should be taken that the boiler saddles do not come in line with the
circumferential seams of the boiler, as the latter at the bottom of
the shell are liable to leak. The U. S. Steamboat-Inspection Rules
state: "All boilers shall have a clear space of at least 8 ins. between
the underside of the cylindrical sheet and the floor or keelson. All
boilers shall have a clear space at the back and ends thereof of 2 ft.
opposite the back connection door, provided that on vessels con-
structed of iron or steel with metal bulkheads the distance back
of the doors and such metal bulkheads shall not be less than 16 ins."
In Scotch boilers the saddles may extend a distance of about %
of the diameter of the boiler around the bottom. The boilers
rest on these saddles and may be connected to them by rods from
pad eyes riveted on the boiler to others on the saddles. Or instead
of this, plates may be riveted to the boilers at each side and these
plates bolted to I beams extending fore and aft that are fastened
to the floors, in which case no rods are required. In both cases,
to prevent fore and aft movement of a boiler, chocks consisting
either of a casting or built up of plates and angles are fastened
to the tank top at the forward and after ends.
Water tube boilers should be located so that their drums are
readily accessible.
In laying off engine foundations give all heights from the center
of the shaft down and allow' % to 1 inch for lining up. They
should if practicable be part of the longitudinals, or if this cannot
be arranged they should be rigidly connected to them or else addi-
tional longitudinals fitted.
Circulating pumps, generating sets, and other auxiliaries should
be securely bolted to foundations that are strongly built of plates
and angles.
Deck Erections. — For the usual cargo steamer the deck erections
above the weather deck consist of a forecastle forward, bridge
amidships, and poop aft, thus giving what is commonly called
"three islands." The ship's frames may extend through the deck
and serve as the vertical stiffeners for the side plating, and to them
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278 HULL CONSTRUCTION
may be bracketed beams over which there may be a light steel deck
with a wood deck on top, or simply tie plates with a wood deck.
There has been a general tendency to increase the length of the
bridge house in the three-island type, but there are two conflicting
considerations to fixing the extent of the deck erections, more
especially in British-owned vessels. These are freeboard on the
one hand and tonnage measurement on the other. An increase in
substantially constructed and efficiently protected deck erections on
a vessel of full scantlings permits of a reduction of freeboard and
therefore of an increase in weight of cargo carried. But if these
deck erections are permanently closed-in spaces, they must be
measured for tonnage and therefore dues based upon tonnage
must be paid on them.
A typical freight steamer as outlined in the table on page 311,
with the machinery amidships, has a forecastle forward for the crew,
then a house amidships with quarters for the engineers, and a poop
aft for stores or for cargo. In some with the machinery aft and
of the three-island type, the crew is forward, then in the center
house or island are the officers' quarters while away aft over the
machinery are the engineers and firemen. In passenger steamers
carrying one class the passengers are amidships, while in those with
three classes, the steerage are forward, the first class amidships,
and the second aft. Here the crew are forward while the officers
and engineers are partly divided with quarters amidships and aft.
Deck houses that are away from the sides of the vessel have
vertical stiffeners with bracket plates riveted to the deck, while
at the top are other brackets which are riveted to the deck house
beams. These beams are connected by tie plates over which a
light wooden deck is laid.
Cementing. — The entire bottom' of a vessel up to the turn of
bilges, and the forward and after trimming tanks should be covered
with the best quality Portland cement — except in oil tankers where
the cement may be omitted in the oil compartments. In the after
trimming tank and in other places where a considerable depth of
cement is required, a thin coating of neat cement is applied to the
metal, then cork, coke or other light material is put over it, and
cement poured on top until the whole mass is solid. Drinking
water tanks should have three washes of neat Portland cement.
The American Bureau of Shipping Rules state: "The inside of
all vessels from the keel to the turn of the bilge to be coated with
approved hydraulic cement. If a mixture of Portland cement and
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PAINTING 279
Sand is used the cement and sand should be mixed in about equal
proportions. The sand should be sharp dry river sand — salt water
sand must not be used. At middle line the cement should be laid
sufficiently thick to form a level surface right fore and aft flush
with the lower side of the limber holes. From middle line to
bilges the cement must cover all the rivet heads on flange or frames
and on inside strake butt straps, being correspondingly thicker
on the outside strakes of skin plating. Vessels fitted with a double
bottom should have a thin coating of cement laid on the upper
side of inner bottom plating. It is recommended to coat the floor
plates with a cement wash in lieu of paint." Lloyd's requirements
are similar to the above. Before applying the cement all mill
scale and dirt must be removed from the plates.
Painting. — All steelwork to be painted must first be carefully
scraped, scaled and cleaned. Care should be taken that no paint
is applied to steel which is to be covered with Portland cement.
The entire structure except as just noted should have a priming
coat of red lead. After this is dry all rivet heads and flush seams
and butts, and in general all exposed flush surfaces should be
smoothed as necessary with an approved rivet cement.
The outer surface of the hull may be divided into three parts:
(1) the under water portion, (2) the part that is under water when
the vessel is loaded and out when she is light called the boot top,
and (3) the top which is exposed to the weather only. The under
water portion should be painted with anti-corrosive and anti-
fouling paints, the boot top with a special paint that is not affected
by the weather or water, and the top sides with a weather paint.
The hull of the vessel inside and out, steel decks, bulkheads and
steel structures, that will be ceiled or covered with wood, should
be given two good coats of red lead, the priming coat mentioned
above being considered the first coat. These two coats of red lead
are in addition to the finishing coats. In some vessels, compart-
ments finished in red lead only shall be given at least three coats
in all. Areas finished in white or spar color should have at least
two coats of the color in addition to the red lead.
Before launching the underwater body, including the rudder,
to a suitable distance above the load water line should be given
one coat of anti-corrosive paint.
There are a variety of anti-fouling and anti-corrosive paints
on the market, a few of which are mentioned below. The Am.
Veneziani Paint Co., New York, N. Y., make a red anti-corrosive
Digitized by VjiOOQ 1C
280 HULL CONSTRUCTION
paint that also protects the steel plates from galvanic action. On
top of this is applied Lamoravia green anti-fouling composition
(made by the same company) which has a grease base. This green
composition is sold in a solid mass and must be heated in a boiler
or kettle to a temperature of 180 degs. F. before it can be applied.
When melted it is easily applied with brushes like any oil paint.
One gallon of the anti-corrosive paint will cover about 28 sq. yds.,
and one gallon of the anti-fouling composition about 6 sq. yds.
Another anti-corrosive and anti-fouling paint for steel vessels
is the International, the makers (Holzapfels Am. Comp. Co., New
York) claiming that it dries quickly and resists the corrosive action
of salt and fresh water.
A plastic paint, trade name Tockolith, is made by Toch Bros.,
New York. After the hull has been scraped and well cleaned,
Tockolith is applied; it strongly resists the corrosive effects of salt
water and abrasion by floating objects which the hull may come in
contact with. When this is dry an anti-fouling paint consisting
of copper and mercury is applied which prevents fouling by bar-
nacles, grass, and other marine growths. For the area that is alter-
nately exposed to the water and to the air, a special or boot topping
paint may be put on. This, as made by Toch Bros., is a black,
waterproof material which retains its color and body, and does not
flake or peel off.
Attention should be called to Bitumastic enamel (American Bitu-
mastic Enamels Co., New York) that is particularly adapted for
interior surfaces as in pontoons of floating docks and of double
bottoms of ships, as it can withstand the presence of oxygen and
water without deterioration. Bitumastic enamel is a solidified
bituminous composition applied hot to any thickness desired,
forming a bright black coating that hardens quickly. The surface
to be coated is first thoroughly cleaned and then given a priming
coat of Bitumastic solution applied cold which is allowed to dry
from 12 to 24 hours. Then Bitumastic enamel is applied, it being
heated to about 380° F., and brushed on while in the molten state.
Owing to its exceptionally adhesive and penetrating nature, the
priming coat forms an intimate bond with the steel, and the base
of the two coatings being identical, they combine, the result being
a hard, heavy and elastic coating which is absolutely impervious
and practically indestructible.
On many ships Bitumastic enamel has been applied to tank
tops and bilges to a thickness of % in., to double bottoms and peak
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ENGINE ROOM 281
tanks ]/% in. on vertical surfaces, and \i in. on shell in double bottom,
and the engine and boiler seatings covered to the height of the plat-
forms with a thickness of % to \i in.
The bottoms of wood vessels are often painted with copper paint.
One maker (Holzapfels) claims that his paint is a reliable substitute
for copper sheathing, and for a long time protects the wood against
the ravages of the boring worm, and the surface against the ad-
hesion of grass, barnacles and mussels. It should be applied with
clean brushes on a dry and clean surface. Only one coat is re-
quired, which takes about half an hour to dry, and when it has dried,
it presents a smooth and enamel-like surface.
For yachts and motor boats, great care is taken to have a perfectly
smooth surface before painting, by puttying all holes and seams.
Then sandpaper to an even surface and apply the first coat of paint,
as Devoe's metallic copper paint, allowing for brown or red six hours
to dry before applying the second coat. When using green, the
first coat must be thoroughly hard before applying the second coat.
On new work, two coats of copper paint should be used. With
brown and red copper paint, the best results are obtained by allow-
ing the second coat 24 hours to dry before launching. When using
green copper paint never launch immediately after applying the
second coat, but allow time for it to become thoroughly hard.
On old boats or on boats whose bottoms are to be repainted they
should be cleaned as thoroughly as possible with a steel wire brush,
and when using brown and red copper paint, it may be applied to
a damp surface if time and place make \t imperative to paint be-
tween tides, although it is best to wait until the bottom is thoroughly
dry. When repainting one coat is generally sufficient, but on bot-
toms where the old paint is pretty well worn off, use two coats.
When using green copper paint, never apply over old coats of
brown or red copper paint. Thoroughly scrape or burn off before
painting, in which case two coats are necessary. In event of green
copper paint having been previously used and same being in good
condition, sandpaper with No. 1 sandpaper and finish with one coat
of green copper paint.
The lower parts of the engine room bulkheads and a large portion
of the boiler room are painted red or brown on account of the wear
and the dirt, while the upper parts may be painted white to improve
the light. Black is used on the gratings, furnace fronts and various
metal parts.
See also Interior Decoration and Painting of Pipes.
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282 HULL CONSTRUCTION
WOOD VESSELS
In the coastwise trade in the United States, wood schooners are
largely employed, and for harbor service, wood lighters, tugs, ferry-
boats and excursion steamers. The displacement is usually calculated
to the outside planking, and the mold loft lines given to the inside.
Motor boats and other small craft with rounded bilges have
steam bent frames, while those with V cross sections have a straight
piece to the bilge and another vertical to it.
In tugs, lighters, schooners, and barges the frames are of several
pieces, that are bolted or treenailed together. All butts of timbers
must be close and not less than \i of their molding. Heads and
heels of the timbers should be square. The frames may be of all
one material as oak, although some vessels have mixed frames, that
is one piece of oak and the next one of chestnut. For the curved
parts as at the bilge, pieces are selected that can be trimmed, when
in place, to the lines of the vessel. The sizes and spacing of the
frames are given in the rules of the American Bureau of Shipping.
The keels are of oak into which is rabbeted the planking. The
planking is of long leaf yellow pine or oak, and at the bilge both the
ceiling (inside planking) and the outside planking are increased in
thickness. Salting is recommended while building. Salt stops
must be fitted in all salted vessels just above the air strakes and at
the turn of the bilge. The use, however, of salt as a preservative is
rapidly giving place to creosote and carbolineums. All vessels must
have proper air strakes or air holes below the two upper strakes of
clamps under all decks. .The planking is caulked with oakum and
cotton, and thus made watertight.
All vessels over iooo tons whose length exceeds ten times their
depth, must be diagonally strapped with iron plates of suitable
width and thickness on the outside of the frames. The straps
should be placed at an angle of 45° and extend from the covering
to the heads of the floor timbers. Four at least of these diagonals
should cross one another on each side in the body of the vessel.
These straps should be riveted together where crossed and should
be let into the timbers and fastened to every frame by two bolts;
the upper end should be connected to a horizontal strap passing
around the hull.
The beams are in a single piece connected to the frames or to
the inside planking by wood knees. At the center they are sup-
ported by a row of wood pillars, or if the span is excessive there
are two or more rows as may be required by the rules.
ioogle
WOOD VESSELS
283
Figure 47. — Midship Section of Four Mast Schooner.
Some large schooners and barges are built with two complete
decks, while others only have one, in which case if the depth in the
clear from the keelson to the deck beam exceeds 13 ft., then hold
beams must be installed.
Vessels for carrying lumber have bow ports, one on each side,
through which the lumber is loaded and discharged. There are no
cross bulkheads, thus giving a long hold. For carrying coal the
arrangement is different, there being transverse bulkheads and
large deck hatches through which the coal is loaded and discharged.
The maximum size of a wood schooner does not exceed as a rule
3,000 tons deadweight, for above this the stiffening required to get
y Google
284
HULL CONSTRUCTION
the necessary structural strength is excessive when compared to
the additional carrying capacity secured. As to barges for carrying
coal a fair average for those along the Atlantic. Coast, that are
towed as from Norfolk, Va., to Boston, Mass., is about 1,800 tons
deadweight, a single tug towing 3 of these barges at a speed of
about 7 knots an hour.
See tables of Schooners, Tugs, Lighters and Motor Boats.
CARPENTER AND JOINER WORK AND INTERIOR
DECORATION
Carpenter work may be said to include the laying of wooden
decks, installing the ceiling and cargo battens in the holds, fitting
masts and spars, bitts, chocks, cleats, etc. Under the heading
Joiner Work is included the building of cabins and fine cabinet
work in mahogany or other expensive wood.
For data on Woods, see Shipbuilding Materials.
For feet board measure, see page 9.
Deck Planking. — The weather decks are usually covered with
yellow pine or white pine planking. The butts should be carefully
arranged so that there are at least three clear shifts between every
two butts in the same beam space. When the planks are 6 ins.
or under in width a single through bolt through every beam is suffi-
cient; when they are above 6 ins. and not exceeding 8 ins. there must
be two bolts in every plank one of which may be a short screw bolt,
while planks exceeding 8 ins. must have two or more through bolts.
The bolts must be properly sunk into the wood, and their heads
Number op Deck Bolts per 1,000 Feet Board Measure of
Planking
Planks 26 ft. long
Thick-
Spacing of Frames in
Inches
Weight of
100 Bolts
ness of
Plank,
Inches
18
20
22
24
26
28
30
32
HIn.
Hln.
V4
2980
2712
2492
2312
2160
2024
1912
1812
2
2235
2034
1869
1734
1620
1518
1434
1359
22.60
39.40
2H
1785
1628
1495
1385
1295
1215
1145
1086
25.48
43.60
3
1490
1356
1246
1156
1080
1012
956
906
28.92
48.00
3H
1275
1162
1067
990
924
867
818
775
32.10
52.80
4
1118
1017
934
867
810
759
717
679
34.75
57.00
4M
994
904
831
771
720
675
637
604
39.40
61.40
5
893
814
748
693
648
608
573
543
40.50
65.55
Thus for a plank 3 ins. thick by 6 ins. wide with a beam (frame) spacing of 24 ins.,
the number of bolts will be -~— * 193 per 1000 feet beard measure.
y Google
CABIN AND STATEROOM BULKHEADS 285
covered with wood plugs of the same material as the deck planks,
imbedded in white lead. The seams between the planks must be
well caulked with oakum and payed with pitch or marine glue.
The margin plank, that is the one next to the waterway, is 8 to
12 ins. wide, and into it are nibbed at the ends the narrower widths
of planking. The planks around the deck house and skylights are
increased in width to 6 to 8 ins. Under the winches, windlasses,
capstans, etc., the planking is increased in thickness so as to be
1 or 2 ins. above the deck.
Cargo battens, often referred to as open sparring or spar ceiling,
are fastened to the reverse frames to prevent cargo from injury
by coming in contact with the sharp edges of the reverse frames.
Lloyd's requires all vessels to have cargo battens in the holds except
those carrying coal, ore, oil, and wood. See Loading and Stowing
of Cargoes. The battens are usually pine planks about 2 ins. thick,
6 to 9 ins. wide and spaced 9 to 12 ins. apart. They may be bolted
to every third or fourth reverse frame, or they may be held in
place by cleats fastened to the frames, in which case they are port-
able. Bulkhead stiffeners having sharp corners should be covered
with battens about 1J^ ins. thick.
Ceiling. — On the tank top of cargo steamers the ceiling, often
spruce or yellow pine, may be omitted except under the hatches and
at the bilges. If the ceiling is omitted under the hatches' the tank
top plating must be increased .08 in. in thickness in way of the
hatchways. Vessels not having double bottoms are to be ceiled,
the thickness varying from 2-inch pine planking in small vessels
to 2 J^ in large, by about 10 ins. wide, arranged in portable sections
approximately 9 ft. long that can be readily handled. The ceiling
must not be fastened through the tank top.
Hatch covers are of spruce or yellow pine, made in sections about
24 ins. wide, and provided with lifting rings. Lloyd's states: "All
hatches to be solid (or gratings of sufficient strength) and not less
than 2J^ ins. thick in hatchways not exceeding 16 ft. in breadth,
when this is exceeded they are to be not less than 3 ins. where fore
and afters are fitted. Efficient supports are to be provided having
at least 19£-inch bearing for the ends of the hatches. Where no
fore and afters are fitted, hatches to be not less than 3 ins. and
supports have not less than 3 ins. bearing for the ends of the hatches
at the end coamings.7'
Cabin and Stateroom Bulkheads. — Bulkheads forming passage-
ways are built with vertical frames which are covered on the outside
Digitized by VjiOOQ 1C
286
HULL CONSTRUCTION
Dome /Toof
S/o/>//y ftoof
QIQQ
F/at ftoof
1
Compan/o/? IVay
Figure 48. — Skylights and Companion Way.
Digitized by VJiOOQLC
• SKYLIGHTS 287
with panels of polished hard wood or pine enameled white and on
the inside with panels or tongue and groove boards. To provide
for a free passage of air the upper part of the bulkhead between the
beams may consist of an ornamental metal grating. The partitions
between the staterooms may be of double tongue and groove board-
ing about % in. thick in two courses at right angles. The doors
to the staterooms are 2 ft. 6 ins. to 3 ft. wide.
Skylights. — Different types are shown in Fig. 48.* The dome
roof over the main cabin saloon and social halls on passenger steam-
ers makes a good appearance. The sloping roof is fitted over engine
rooms and may be built of steel plates and angles instead of wood.
Companionways are of steel, teak, or mahogany. For motor
boats and fine yachts the skylights, companionways, and deck
houses are of mahogany or teak.
Miscellaneous Notes. — Thwartship flights of stairs should be
avoided as much as possible, for in descending a person has to meet
the rolling of the vessel. In laying out stairs, take the sum of
two risers from 24 ins. and the remainder will be the required tread.
Berths in passenger quarters are of metal, about 30 ins. wide
and approximately 36 ins. between the upper and lower one. In
cabins de luxe are beds as on shore. In crew's quarters pipe berths
may be installed about 2 ft. 3 ins. wide by 6 ft. 3 ins. long, the
bottom of the first berth being 10 ins. from the floor and of the
second 46 ins. from the floor. The U. S. Steamboat-Inspection
Rules state that berths can only be two high.
The height of a chair seat or seats along the side of an excursion
steamer varies from 17 ^ to 18 ins. above the deck. Depth of seat
15 to 16 ins.
Writing and dining tables are 2 ft. 5 ins. high. Mess tables
and benches are of white ash.
Interior decoration and painting should be governed by the trade
and climate. If the vessel is to run in the tropics the rooms should
be light and airy and finished off in white; if in cold regions then
dark woods and the reverse of the treatment for the tropics should
be followed.
Staterooms are invariably finished off in white enamel paint and
mahogany — and the smoking rooms in oak. If the deck heights
permit, a ceiling may be built under the beams, thus giving a space
in which wires and pipes may be run and yet be easily accessible by
having a few panels portable.
* From Practical Shipbuilding, A. C. Holmes.
Digitized by VjOOQiC
288 HULL CONSTRUCTION
As a vessel's saloons are seldom high enough for indirect lighting,
wall brackets are necessary. The lighting of a saloon at night is
improved if lights are placed around the skylight, otherwise the
skylight makes a black patch and puts the middle of the room in
shadow.
New wood, particularly on outside work, as deck houses, hatches,
spars, etc., should first have a coat of a wood primer. Open-
grained woods, as oak, ash, chestnut, mahogany, and walnut, should
then be filled with a wood filler. After the filler is dry (24 hours)
it should be sandpapered with the grain of the wood to a smooth
surface. Close-grained woods, as cherry, birch, white wood, and
maple, should have a coat of primer but the filler may be omitted.
On interior work it is not necessary to use both primer and filler,
the primer alone on close-grained woods or the filler alone on open-
grained being sufficient. After the primer and filler or either
alone have been applied, and the surface is dry, it is then ready
for varnishing. Painting and varnishing should not be done on
a damp or cold day. One gallon of varnish will cover about 500
sq. ft. for the first coat and about 600 sq. ft. for the second.
Ceilings, furring strips, battens and the faying surfaces of wood
decking should be well painted; the wood to be painted on all
sides except for decks and such work as is to be finished bright.
Below are abstracts from the specifications of a steamer for the
U. S. Coast Survey. "Areas finished in white or apar color shall
have at least two coats of the color in addition to the red lead
specified. Soft woods, in furniture details and the like will have a
coat of white shellac and where painted shall have at least three
coats of oil paint. Wood work to be bright shall be filled, shellacked,
varnished and rubbed down to a dull finish. In all cases each coat
of paint or varnish must be dry and hard before the next coat is
put on.
"Cork paint shall be applied to interior surface of outside plating
and to frames in living quarters, storerooms and holds.
"A wash strake 4 ins. high shall be painted around the bottom
of all steel and wood bulkheads in living quarters and passages, the
color to match the color of the deck surface in the respective com-
partments.
"All piping whether bare or covered shall be painted to match
the compartment in which it runs.
"Galvanized work may be painted with aluminum paint, as also
watertight door dogs, grab rods, and steam radiators in the crew's
quarters, while the radiators in the officers' will be finished in gilt.
o
MEASURING SCREWS
289
"The waterways on the upper deck and the exposed upper deck
plating way forward shall be painted buff, as also the canvas cov-
ered deck forming the top of the deck house. Linoleum shall not
be painted but shall be thoroughly cleaned and heavily waxed.
If directed it may be shellacked."
Cork paint is not used in holds of merchant ships as it is too expen-
sive, but is used in the living quarters.
Measuring Screws. — Flat head wooden screws are measured over
all, round head from under the head, and oval head from the edge
of the bevel. Lag screws have square heads and are measured from
under the head. Machine screws, fillister and round heads, are
measured from under the head, flat heads over all, and oval heads
from the edge of the bevel.
Lag Screws
Square heads, cone or gimlet points. Gimlet point screws only
supplied from 5/ie in. to J£ in. dia. inclusive.
Diameter of Screw (Inches)
Approx-
imate
Length
M*A
%
i7»
a
&*%
H
H
1
IX
VA
of
Thread
Length under Head to Extreme Point (Inches)
Diam-
eters
IX
VA
VA
VA
.* To head
2
2
2
2
2
VA
2H
2H
2H
2A
2A
2X
2
3
3
3
3
3
3
3
2\i
3H
3^
3H
SX
3^
3A
SX
3A
2X
4
4
4
4
4
4
4
4
3
4^
VA
4H
VA
VA
VA
VA
VA
3X
5
5
5
5
5
&A
5
5
5
4
5H
VA
5H
VA
VA
VA
VA
VA
4
6
6
6
6
6
6
6
6
6
6
VA
M
6H
QX
VA
VA
VA
QA
VA
; b
7
7
7
7
7
7
7
7
5
7A
7H
7X
7X
7X
7X
7A
7H
; e
8
8
8
8
8
8
8
8
6
9
9
9
9
9
9
9
9
6
10
10
10
10
10
10
10
7 «
11
11
11
11
11
11
11
7
12
12
12
12
12
12
12
7
Threads Per Inch
10
7
7
6
5
VA
4M
3
3
3
Size of Heads (Inches)
% i*
A
n
*A
n is
VA
1tb«
VA
ltt
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291
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Weight of Lag Screws per 100
Length
Under
Diameter
Head
to Ex-
treme
Point
A
H
i7*
H
A
%
X
%
1
IK
1M
IX
lb.
lb.
lb.
lb.
lb.
lb.
lb.
lb.
lb.
lb.
lb.
lb.
VA
4.2
6.5
9.2
13.0
IH
4.7
7.1
10.0
13.8
2
5.2
7.7
10.9
14.0
23.0
24.8
2X
5.7
8.4
11.8
16.1
24.5
27.3
2H
6.2
9.2
12.7
17.4
26.0
29.0
43.0
3
7.2
10.6
14.6
•19.0
29.2
32.9
48.3
75.0
3M
8.2
12.0
16.6
21.5
32.5
36.9
53.8
78.5
90
4
9.2
13.5
18.8
24.0
35 .9
41.0
59.6
82.0
99
4H
10.2
15.0
20.7
26.5
39.3
44.9
65.5
86.0
108
5
11.3
16.5
22.8
29.0
42.7
48.8
71.5
90.0
118
i50
5X
12.4
18.0
24.9
31.5
46.1
52.7
77.5
98.0
128
163
6
13.5
19.5
27.0
34.0
49.5
56.6
83.5
106.0
138
176
240
7
31.1
39.0
56.3
64.5
95.5
122.5
158
203
270
8
35.2
44.0
63.1
72.5
107.6
139.0
178
230
300
420
9
49.0
69.9
80.5
119.8
155.6
198
257
332
468
10
54.0
76.7
88.5
131.0
172.0
219
284
365
516
11
83 .5
96.5
143.1
188.5
240
311
395
564
12
90.5
104.5
155.4
205.0
261
338
425
612
13
112.5
167.6
221.5
282
365
459
660
14
121.0
179.8
238.0
304
393
493
710
15
129.5
192.0
255.0
326
421
527
760
16
138.0
204.0
272.0
348
449
562
810
Number of Lag Screws in 250-lb. Keg
(Approximate)
Length
Under
Diameter
Head to
Extreme
Point
i8«
*A
X
%
X
IX
5700
3700
2
4600
3300
1600
1000
2A
3600
2800
1400
900
500
3
3000
2500
1300
800
450
3X
2600
2300
1200
700
425
4
2300
1900
1000
625
375
4K
2000
1700
850
550
325
5
1800
1500
700
500
300
5H
1600
1400
650
450
275
6
1400
1250
600
375
250
7
1100
550
325
225
8
1000
475
270
200
292
Google
LAG SCREW TESTS
293
Lao Screw Tests
Screws drawn out of yellow pine
Diameter of Screw .
Wood (deep) inches
Drew out (lb.)
Standard Steel Wire Nails*
Sizes, Lengths, and Approximate Number per Pound
Sises
Length
(Inches)
Common
Diameter
B. W. G.
Inch
No. Per
Pound
2d
3d Com
4d
6d
6d
7d
8d
9d
lOd
12d
16d
20d
30d
40d
50d
60d
.072
.083
.102
.102
.115
.115
.124
.124
.148
.148
.165
.203
.220
.238
.259
.284
900
615
322
250
200
154
106
85
74
57
46
29
23
17
13^
10h
* Common nails have flat heads and may be barbed or smooth. Brads have
small circular heads and come in the same mses as common nails. There is little
difference in the weight of a common nail and a brad.
Square Boat Spikes
Approximate Number in a Keg of 200 Pounds
Sise
Length of Spike (Inches)
(Ins.)
3
4
5
6
7
8
9
10
11
12
14
16
M
3000
2375
2050
1825
A
1660
1360
1230
1175
990
880
H
1320
1140
940
800
650
600
525
475
A
. . .
600
590
510
400
360
320
230
8
. . .
450
375
335
300
275
260
240
...
260
240
220
205
190
175
160
11
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294 HULL CONSTRUCTION
STRUCTURAL STRENGTH
As to proportions of vessels for strength, Lloyd's Rules state:
"All vessels exceeding 14 lengths in depths to have special stiffen-
ing which must be approved by the Committee, and all exceeding
13J^ depths must have a bridge extending over the midship half
length of the vessel or such special compensation for extreme pro-
portions as may be required by the Committee."
The American Bureau of Shipping Rules state: "Their rules
apply only to steam vessels the length of which does not exceed 11
times their depth and to sailing vessels the length of which does
not exceed ten times their depth. Vessels whose length to depth
exceed these proportions must have their scantlings augmented
and additional strengthening fitted."
For ordinary vessels of standard proportions built according to
Lloyd's, the American Bureau of Shipping, or other recognized so-
ciety, usually no strength calculations are made, but they are made
for commercial craft of exceptional proportions, and for warships.
Below are outlined strength calculations and the curves that can
be plotted for them.
Curve of Weights.* — Divide the length of the vessel into a number
of equal parts, and calculate the weight of the materials for one foot
of length. These weights per foot are then set off from the base
line on their respective ordinates and the points joined together,
forming a jagged line which represents the hull weights.
Next calculate the weights of the cargo, coal, engines and boilers,
and stores — and if a warship, of the guns and armor — which can
be added as rectangles to the curve of hull weights. The machinery
calculations can be divided as follows:
(1) Boilers. — Everything connected with the boilers as uptakes,
funnels, pumps, etc., to be uniformly distributed over the length of
the boilers.
(2) Engines. — Everything connected with the engines as con-
densers, pumps, etc., all being assumed to be uniformly distributed
over the length of the bed plate.
(3) Shafting. — Weights are taken from the forward end of the
thrust to the after end of the propeller shaft, and assumed to be
distributed over this length. The weight of the bearings is to be
included.
(4) Propeller. — The weight is assumed to be uniformly distributed
over the length of the propeller boss.
♦Abstracts from Ship Cal. and Cons., G. Nicola.
Digitized
by Google
CURVES OF AN OIL TANKER
295
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Digiti
zed by G00gk
296 HULL CONSTRUCTION
A curve including both the hull and machinery weights, and if
a warship the guns and armor, can be plotted, the area of which is
equal to the displacement of the vessel, and the center of gravity
of this new curve should come over the center of buoyancy.
Curve of Buoyancy. — The above curve gives the weight per foot
of a vessel and to find the support given it by the water, a curve
of buoyancy is plotted. To do so, the displacement in tons per foot
of length is calculated by finding the area of each section in square
feet (the sections are preferably taken at the same intervals as
selected when the calculation for the curve of weights was made),
multiplying by 1, as a section is assumed as 1 ft. in length, and di-
viding the product by 35, to get the buoyancy in tons per foot
of length in salt water. These quantities are laid off at the same
intervals as selected for the curve of weights, and a curve through
the points is known as the curve of buoyancy, the area of which
should equal the displacement of the ship.
By examining the curve of buoyancy in conjunction with that
of the curve of weights, the portion of the vessel where the weights
exceed the supporting pressure due to the buoyancy of the water
may be noted.
Curve of Loads. — By measuring the difference between the
ordinates of the curves of weights and buoyancy, and laying them
off on the same intervals, a curve of loads is obtained. Having this
curve, a ship may be considered as a beam and the calculations
pertaining to shearing and bending be made. For instance, suppose
a vessel is supported at the bow and stern by a wave, leaving the
middle portion unsupported. This is a case of a beam supported
at the ends with a uniformly distributed load, if the weight per foot
of length of the cargo and machinery space is the same. Or should
the vessel be light and the machinery be amidships, this would be
a case of a beam supported at the ends and loaded in the middle.
Similarly a vessel may be supported at the middle by a wave, the
weights at the ends tending to cause her to hog.
- Thus by the formula •*- = -j the stress on any portion of the hull
may be obtained, but before using this formula there must be
found: (1) the position of the neutral axis which passes through
the center of gravity of the section; and (2) the moment of inertia
of the section about the neutral axis.
Two calculations are necessary, one for the section under a hog-
ging moment and the other under a sagging. In each case the posi-
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CURVE OF LOADS
297
tion of the neutral axis and moment of inertia of the section will be
different.
As to the stresses in the materials in both instances, that above
the neutral axis will be subjected to a different one than below.
For materials in tension, allowance must be made for lightening
and rivet holes, but in compression this is not necessary. Wood is
commonly taken as being equivalent to ^ its area in steel for ten-
sion and compression, while armor is considered to be of no value
in tension, but is in compression.
Neutral Axis and Moment of Inertia Calculations. — Take a plan
of the midship section of a vessel with all the scantlings on it and
draw a horizontal line one-half the depth of the section, assuming
this line as the temporary neutral axis. Lay off a table as below,
the areas being in square inches and the distance their center of
gravities are from the assumed neutral axis in ft.
1
Items
2
Scant-
lings
in Ins.
3
Effective
Area in
Sq. Ins.
4
Lever
in
Ft.
5
Moment
6
Lever
in
Ft.
7
Moment
of
Inertia
8
A A
X A»
A
M
J
%
In Column 5 some of the items are above the neutral axis and
others below, hence the algebraic sum M of this column is divided
by A, the sum of the effective areas, the quotient being the distance
in feet the real neutral axis is from the assumed.
The levers in feet in Column 6 are the same as those in 4, and
by multiplying these levers by the moments in Column 5, there is
obtained the areas times the square of their distances from the as-
sumed neutral axis, which are positive quantities, their sum being
designated by 7.
For the portions of the sections which are vertical as the strakes
of shell plating at the water line, an addition is required for the
moment of inertia of the items about axis through their own cen-
ters of gravity, which is given by the formula ^i X h*. For por-
tions of the sections which are horizontal as in the deck plating,
where h is small, the additions may be neglected.
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298 HULL CONSTRUCTION
Thus the moment of inertia about the assumed neutral axis is
I a = / + h ana" to transfer this moment to the true neutral axis,
from I a subtract the product of the effective areas A times the
square of the distance d} the real neutral axis as found above is
from the assumed neutral axis. Therefore the real moment of
inertia = I a — A X <P.
Knowing, then, the location of the neutral axis and the moment
of inertia, by applying the formula — = t there can be calcu-
V *
lated the stress on the material farthest from it.
Example. Steamer 350 ft. long, 60 ft. 4 ins. beam, 28 ft. molded depth, load
displacement 9600 tons, draft 23 ft. 9 ins., neutral axis above base 12 . 82 ft., distance
(y) top of section from neutral axis 23.18 ft., moment of inertia about neutral
axis 285442.
The maximum bending moment on a wave crest is usually taken as ^ of the
displacement times the length, thus in the above steamer the maximum bending
moment M is 96°° * 35°' = 96000 foot-tons.
oo
Using the formula —- = y, where the greatest stress p in tons per square inch
M. £6000 g^
under a hogging strain = / = 285442 « to ■■ 7.79 tons per square inch.
V "23TI8 12314
Stresses as just given vary in different vessels, for in large ones
a stress of 10 tons per square inch is considered safe on a standard
wave length, that is, one supporting the bow and stern, for such a
Wave would doubtless never be encountered, while ships of 300 and
400 ft. have stresses of 6 to 7 tons.
For hogging as in the above the full area below the neutral axis
is taken, and often A the full area above the axis to allow for rivet
holes.
To obtain the greatest stress under a sagging. strain, a new
moment of inertia calculation is necessary, otherwise the work is
the same. For sagging the full area above the axis is' taken, and
A the full area below the axis to allow for rivet holes.
Curve of Shearing Stresses. — Calculate the area of the curve of
loads from the forward end, and at each interval (using the same
intervals as when making the calculations for the curve of weights),
set off the areas and draw a line through the points. The result-
ing curve is the curve of shearing stresses. From it the shearing
force at any point in the length of a vessel may be expressed as the
algebraic sum of all the stresses caused by the excess of weight
or buoyancy from either end.
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CURVE OF BENDING MOMENTS 299
The shearing force in a ship amidships is usually zero, and is at
a maximum about a quarter the length from each end. This in
large ships calls for extra riveting, for Lloyd's Rules state: "In
vessels of 480 ft. and upwards, the landing edges are to be treble
riveted for one-fourth the vessel's length in the fore and after
bodies for a depth of one-third* the depth."
Curve of Bending Moments. — This is obtained from one of shear-
ing stresses by taking the area from the forward end to any given
ordinate and laying this area off perpendicular to the base line.
A curve through the points gives the curve of bending moments.
The bending moment at any point in the length of a vessel may be
expressed as the algebraic sum of all the shearing stresses from
either end.
The maximum bending moment may be approximately found by
multiplying the displacement D by ^ to Jg of the length L of
D V Li
the ship, thus — ~= — . See example above.
The minimum tension per square inch on the sheer strake equals
maximum bending moment X distance neutral axis below sheer strake
total moment of inertia
In all the above calculations the ship is assumed to be in still
water, but as this is seldom the case, the curves do not represent
the true stresses as experienced when in a seaway where there
is a continuous changing of excess weight over buoyancy. Hence
ample factors of safety must be allowed.
Transverse Section. — As a vessel may be taken as a beam and
calculations as outlined above made on her strength, the form of
transverse or cross section is important. The average vessel may
be assumed to have a rectangular one, and although such a section is
a strong one, yet by adding a center longitudinal web or bulkhead
its strength can be greatly increased, the web taking the strains
to a large extent off the sides or shell plating, and furthermore
serving as a support to the deck and deck beams.
Hence the importance of a fore and aft bulkhead, particularly in
wide and shallow draft vessels, which should not be abruptly
stopped but continued some distance as a girder with a gradually
decreasing strength section. In many vessels it is not practical,
owing to the nature of the cargo to be carried, to have a fore and
aft bulkhead, and instead a heavy girder is connected to the under
side of the deck beams, which is supported by widely spaced pillars.
(See Pillars.) The depth from the tank top to the main deck
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300
HULL CONSTRUCTION
and the distance to the first tier of beams must not exceed a certain
limit (see Lloyd's, British Corporation, etc.)i for if they do the
rules require the sizes of the frames and other parts to be increased.
Submarines are given circular, or nearly so, cross sections, for the
reason that flat surfaces would require exceptional stiffening to
prevent them from collapsing. For when a body is submerged in
water every part of its surface is subjected to an equal pressure,
viz., top, sides, and bottom, and the strongest form to resist these
pressures is a circular one. Submarines have sufficient strength
to sink to a depth of about 100 ft.; some have gone to 175 ft.
SPECIFICATION HEADINGS
In preparing the specifications of a vessel it is often of service
to have a list of the hull, engine, boiler and miscellaneous equip-
ment that may be required. Below is a list that will serve as
a guide. .
Introduction
Dimensions, class and general
characteristics of the vessel
Carrying capacity — passengers
and freight — speed
Classification Society
Payments
Insurance
Trial
Builder's guaranty
Frames, size pi and spacing
Hatches
Web frames
Stem and stern posts
Floors
Rudder
Beams
Deck house
Beam brackets
Bridges
Keel
Masts and rigging
Keelsons
Watertight doors
Side stringers
Cement
Inner bottom
Bollards (bitts) and chocks
Longitudinals
Rail and awning stanchions
Foundations for engines,
boilers,
Bulwarks
pumps, etc.
Pillars (stanchions)
Scuppers
Boat davits
Shell plating
Bilge Keel
Anchor, chain, chain stoppers
Joiner work—- passengers', crew's
and officers' quarters
Cargo ports
Airports
Bulkheads
Cargo battens
Painting
Deck plating
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MACHINERY
301
Machinery
Engines — type, I. H. P.
Steam
Hot well
Evaporator
Revolutions
Covering of steam and exhaust
Number and size of cylinders
pipes
Cylinders — liners
Boilers — type and size of
Relief valves and drains
Steam
Bed plate
Heating surface and grate
Columns
area
Connecting and piston rods
Circulators
Pistons
Gauges — steam and water
Water service
Fittings — safety valve, blow-
Lubricating system
off valve, feed water con-
Valves— piston — slide
nections, etc.
Reversing gear
Grate bars
Turning gear •
Covering
Throttle valve
Draught — natural or forced
Separator
Fans — capacity — turbine or
Shafting — crank — thrust — line
steam engine driven.
Bearings — linings
Propeller — size — blades bolted
Uptake and stack
Boiler feed pumps
on — material
Injectors
Fairwater
Floor plates in engine and boiler
Condenser — type
Sq. ft. of cooling surface
rooms
Spare parts for engine, boilers,
Fittings
and auxiliary machinery
Air pumps
Fuel oil pumps
Circulating pump
Superheaters
Feed water heater
Systems and Equipment
Electric
Ventilating
Size and type of generating
Pressure or exhaust
units
Fans
Location ,
Ducts
Light and power circuits
Ventilators
Wiring system — size of wires
and conduits
Plumbing
Switchboard
Toilets, washstands, bath tubs
Number of lights, size and
where located
Check valves on discharge
pipes
Searchlights
Storage batteries
Drainage
Pumps
Sluice valves
Heating
Steam, thermotank or electric
Strainers
y Google
302
HULL CONSTRUCTION
Systems and Equipment — Continued
Fire systems
Water and steam
Pumps
Hose
Fresh water
Pumps
Tanks
Refrigeration system
C02, ammonia or dense air
Insulation
Ship machinery
Steering engine
Capstan
Windlass
Winches
Interior communication
Signal system between pilot
house and engine room
Life boats, rafts and life pre-
servers. If a U. S. vessel, see
U. S. Steamboat Inspection
Rules.
Carpenter's stores
Boatswain's stores
Lights
If [a U. S. vessel, see
U. S. Steamboat Inspection
Rules
Navigating instruments
Tarpaulin covers
Baking outfit
Galley outfit
Pantry outfit '
Glassware
Dishes
Cutlery and plated ware
Linen
Bedding
Flags
Wireless
Storm oil
HULL WEIGHTS
The difference in finished steel weights of a ship built to Lloyd's,
Bureau Veritas, and British Corporation Rules is very small.
For quickly determining the approximate weight of a steel hull
either of the formulae given below may be used; one is known as
the cubic and the other as the surface foot.
Cubic. — Weight of finished steel in hull in lb. = length X breadth
X depth X coefficient. The coefficient varies from .0036 to
.0043, the larger coefficient for vessels having the greatest
ratio of length to depth and breadth to depth.
ioogle
WEIGHTS
303
Surface Foot — Let d = depth of vessel measured from the
bottom of the flat plate keel to the uppermost continuous
. deck. Then surface foot = length X (breadth + 2d).
The pounds per square foot vary from 97 to 125 and taking
a mean value of 111, the surface foot found by the formula,
length X (breadth + 2d) multiplied by 111 will give the
weight in lb. of the finished steel in a vessel.
Of the total weight of hull steel, from 70 to 80% is taken up by
the keel, frames, beams, keelsons, deck and shell plating. The re-
maining 30 to 20% represents bulkheads, engine foundations,
masts, etc.
Percentages of total angles and plates for ordinary vessels of
about 400 ft. long and .75 coefficient, built to Lloyd's 100 A. I.
three deck class, with deep framing in lieu of hold beams, and with
double bottoms, are given in the following table. C is a steamer
built to British Corporation Rules of the highest class, but other-
wise similar to A and B.
Table op Weights* ,
Items
A
Steamer
B
Steamer
c
Steamer
Main frames and reverses
Per cent.
7.5
2.1
1.8
1.7
4.4
5.8
6.9
3.3
2.2
2.4
10.4
1.8
4.8
1.6
4.8
26.8
3.3
Per cent.
7.6
2.2
2.0
1.3
6.2
5.8
6.3
2.7
2.2
1.7
10.0
1.7
4.6
2.1
4.2
26.4
3.9
Per cent.
7.2
Tank frames and reverses ,
1.5
Connecting angles, etc., in tank
Hatches
1.7
3.2
Side keelsons
3.8
Main deck plating
6.2
Upper deck plating
6.3
M ain deck beams
2.2
Upper deck beams
1.8
Casings ."
2.4
Floors and Intercostals
7.8
Center longitudinal and margin plate. .
Tank top .-
1.7
3.5
Tunnel/.
Bulkheads
1.9
3.0
Shell
26.6
Erections
5.8
* From A Class Book on Naval Architecture, W. J. Lovett.
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304
HULL CONSTRUCTION
Steel Weights of a Steamer*
430 ft. long, 46 ft. beam, 34 ft. 3 ins. deep, built to Lloyd's 3-deck
rule.
Part of Hull
Keel bars and stem
Stern post, rudder frame and struts
Frames, reverse frames and doub-
lings
Floors and tail plates
Beams and carkngs
Keelsons .'
Bulkheads (W. T.).
Bunker casings
Engine and boiler seats
Shaft tunnel and stools
Inner bottom plating
Shell plating, including bulkhead
liners
Stringers and ties
Deck plating
Cargo and coal hatches ....
Engine and boiler casings
Deck houses
Sundry deck and hold work ....
Fresh water tanks
Slip iron
Molding and copes
Rivet heads.
Finished steel, weight.
Weight
in
Tons
3.5
20.0
275.0
301.0
225.4
142.5
102.7
40.0
25.0
37.7
119.4
734.2
217.6
305.3
37.5
77.6
140.0
25.0
13.2
57.0
46.5
44.0
2990.0
Forcings .
Angles
Plates.
Bulb Tee
Slips
Moldings
Castings
Rivet heads,
Summary
Tons
6.0
587.0
2063.6
168.4
57.0
46.5
17.5
44.0
Total 2990.0
* From the Naval Constructor, G. Simpson.
See also table of Merchant Vessels.
MACHINERY WEIGHTS
Total weight of machinery (steam engine, boilers, water, etc.)
is about 448 lb. per i. h. p. for forced draught boilers and 558 lb.
per i. h. p. for natural draught.
The i. h. p. per ton of engines, boilers, and water (that is, water
in boilers) is about 5.5. Thus the machinery weight of a steamer
460 ft. long, 58 ft. beam and 27 ft. draft, having an engine of 4,000
4000
i. h. p. would be -=-=- = 730 tons approximately.
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MACHINERY WEIGHTS j 305
or making a preliminary estimate note the following weights:
Main engines. 60 lb. per i. h. p.
Shafting and wheel 40 lb. per i. h. p.
Condensing equipment 15 lb. per i. h. p.
Auxiliary machinery 20 lb. per i. h. p.
Piping 15 lb. per i. h. p.
Boilers, see following tables, also section on Boilers.
Total machinery of stern wheelers built to run on the Mississippi
River (U. S.) weigh from 415 to 560 lb. per i. h. p.
The sum of the cylinder diameters in feet multiplied by 2.4 to 2.5
gives an average length of the engine room in feet for a triple
expansion engine. If all the pumps are independent of the engine
the above length should be slightly increased.
The total length of the boiler room with single end Scotch
boilers and one stokehold is equal to the length of the boilers
multiplied by about 1.83. When there is a common stokehold for
boilers arranged fore and aft, it is usual to allow 2 ft. to 2 ft. 6 ins.
more than for a single stokehold. An approximate figure for the
total weights in a boiler room in tons may be obtained by multi-
plying the volume of the boilers in cubic feet by .04 to .05 de-
pending on whether the boilers have natural or forced draft.
(From Mar. Eng'g Estimates, C. R. Bruce.)
Machinery Weights*
Engine
I. H. P.
Boiler
Press
Engine
Weight
Boilers
Funnel,
Mount-
ing, etc.
Water
Total
Weight
Per
I. H. P.
19 X 30 X 50
33
22 X 35 X 57
42
24 X 38 X 62
42
24 X 39 X 64
33
30 X 46 X 75
45
31 X 50 X 82
57
860
1383
1585
1786
2600
2850
160
150
160
160
160
160
(tons)
68
105
125.
93
157
251
(tons)
35.8
62.5
64.
80.
116.5
146.
(tons)
8.5
17.6
20.9
12.4
31.4
42.5
(tons)
20.7
35.
46.
52.
80.
82.5
(tons)
133.
221. »
363.9 *
237.4
385.75
535.5*
(tons)
.154
.16
.166
.133
.148
.184
* Marine Eng'g, Seaton. l Includes 2 tons of spare gear. * Includes 8 tons of
spare gear. * Includes 3 . 5 tons of spare gear.
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306
\
HULL CONSTRUCTION
Weights op Engines Au>ne*
Horse Power
Type
Weight
Lb.
12
Compound
n
u
u
Triple
tt
tt
tt
<«
n
tt
u
tt
tt
290
25
590
70
1,509
3,050
1,075
2,100
3,050
4,450
5,900
10,000
12,992
17,024
22,200
90
75......
150
200
275
325
425
550
800....
1,000
1,500
32,150
* High speed engines built by Chas. Seabury & Co., New York.
Boiler Weights. — Weight of Scotch boilers without water per
sq. ft. of heating surface is from 25 to 30 lb., and for water tube
12 to 20. The weight of the contained water per square foot of
heating surface is from 12 to 15 lb. for Scotch boilers and from
1.5 to 3 lb. for water tube. Thus Scotch boilers with water will
weigh from 30 to 35 lb. per square foot of heating surface, and
water tube will weigh from 13.5 to 23 lb.
Weight of 3-furnace single-end Scotch boiler, 10
ft. 6 ins. long by 13 ft. 6 ins. dia., without water 25 tons
Weight of water 15
Total 40 tons
Weight of 3-furnace double-end Scotch boiler, 18
ft. long, 13 ft. 6 ins. dia., without water 45 tons
Weight of water 25
Total 70 tons
Three-furnace double-end Scotch boiler, 21 ft. 10 ins. long by
16 ft. 5 ins. dia., weighed empty, 105 tons.. Twenty-nine such
boilers were installed on the White Star steamer Britannic (1915).
[Steamer Britannic mentioned above sunk in European War 1916.]
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MISCELLANEOUS WEIGHTS 307
Four-furnace single-end Scotch boiler, 11 ft. long
by 16 ft. dia., without water 40 tons
Weight of water 20
Total 60 tons
Four-furnace double-end Scotch boiler, 20 ft.
long by 16 ft. dia., without water 70 tons
Weight of water . . 40
Total 110 tons
Formula for, Finding Weight of a Single or Double-End Scotch
Boiler*
Let D = diameter of boiler in feet
L — length of boiler in feet
P — working pressure
C for ordinary single-end boilers «= 725
C for ordinary double-end boilers = 765
Weight of bare boiler in tons = ^ X L^X \/P
Formula for Finding Weight of Water (assumed to be cold) in
Scotch boilers.
Assume the water to be 7 ins. above the top of the combustion
chamber
D = diameter of boiler in feet
L = length of boiler in feet
ryt w t
Weight of water in tons = —
Miscellaneous Weights.
Ordinary fire bars, 5 ft. 6 ins. long 66 lb.
Ordinary fire bars, 5 ft. 0 ins. long 691b.
Howden's fire bars, 5 ft. 9 ins. long 47 lb.
Howden's fire bars, 5 ft. 6 ins. long 45 lb.
Weight of fire bricks 140 lb. per cubic foot.
Weight of covering (lagging) about one-half a pound
per square foot.
Above formula from Marine Boilers, J. Gray.
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308
HULL CONSTRUCTION
Weights of Water Tube Boilers1
(No water included.)
Grate Surface
Sq. Ft.
Heating Surface
Sq. Ft.
Weight
Lb.
3.5
120
222
333
516
307
521
750
1,087
1,310
1,649
1,920
2,846
1 1,650
* 3,300
1,290
2,170
4,020
6,520
3,550
5,600
8,180
4.94
9.5
12.25
8.48
12.9
21.0 :
33.4
9,670
14,100
16,500
22,680.
41.0
39.5
53.75
77.57
29,460
52.0 :
17,000
30,000
101.0
1 Boilers built by Cbas. Seabury & Co., New York. They have a single steam
drum connected to two lower or mud drums, one on each side, by two nests of
bent tubes inclosing a large combustion chamber.
' Special.
Finished Weight of Machinery, "Steam Up,1' cargo steamer 377
ft. bet. perps., 49 ft. 3 ins. beam, 28 ft. 9 ins. deep, draft 23 ft. 6
ins., displacement 9750 tons, block coefficient .78. Two single end
Scotch boilers 16 ft. dia. X 12 ft. long, 180 lbs. working pressure,
each with three furnaces, Howden's forced draught, total heating
surface 6200 sq. ft., total grate area 120 sq. ft., engine jx »
68 revs, per min., 1. H. P. 1900, giving a speed of 10 J4 knots.
Main Boilers (bare)
Boiler mountings. . . . '.
Furnace fittings (ex. fronts)
Smoke boxes
Funnel and fittings
Ventilators
Floor plates, gratings, etc. . .
Sundries in boiler room
Water in main boilers
Lagging
Fire bricks and clay
207.20
WEIGHTS OF DIESEL ENGINES
309
Howden's Forced Draft
Fan engine
Furnace fronts ".
Retarders
Air trunks and heater boxes
Main Engines — proper.
Condenser
Thrust shaft and block
Tunnel and propeller shaft
Pipes, valves and pieces
Ballast pipes and chests
Floor plates, gratings, etc
Special spare gear
Outfit and sundries in engine room .
Water in engines
Lagging
Auxiliaries
Weir's pumps and heater
Filter
Evaporator
Ballast pump
Donkey pump
Fresh water donkey pump
Telegraphs
Ash hoist
Auxiliary condenser
Winch Outfit
Donkey boiler (complete)
Feed pump for
Winch pipes
Total Weight of Machinery, "Steam Up" . .
Tons
2.5
3.15
1.75
4.6
107.0
9.5
7.25
45.85
9.0
5.7
11.8
12.0
5.0
4.5
1.0
3.8
.8
2.5
1.6
.4
.3
.1
.8
1.4
20.0
.3
5.2
Tons
12.00
218.60
11.70
25.50
475.00
[Above steamer from Marine Eng'g Estimates, C. R. Bruce.]
Weights of Diesel Engines
500 h. p. Diesel engine in motor ship Vulcanite, 180 r. p. m.,
engine alone weighed 42 tons or 188 lb. per b. h. p., entire plant
with piping reservoirs, etc., 85 tons, equivalent to 380 lb. per b. h. p.
Twin Diesel engines with a total of 1,600 h. p. in motor ship
Monte Penedo, both weighed 110 tons, engines alone, piping reser-
voirs, and accessories 44 tons, reserve air compressor about 6 tons,
total 224 lb. per b. h. p.
See also section on Diesel Engines.
DATA ON VESSELS
Merchant Vessels. — Under this heading are included ocean-going
vessels for carrying passengers and freight. See also sections on
Types and Structural Features.
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HARBOR VESSELS 313
Harbor Vessels and Steam Yachts. — Under this heading are
included steamers engaged in the excursion business carrying pas-
sengers and freight for short distances but never out of sight of land,
also tugs and lighters. See pages 314 and 315.
Excursion steamers are usually side wheelers, although stern
wheelers are very common on the Mississippi River and its tribu-
taries. Side wheelers with large deck areas are obtained by extending
the decks over the hull. In estimating on the carrying capacity,
7 sq. ft. per person is a fair average. Few are built to the rules of
any society or with double bottoms, the owners following the
structural details of their previous vessels. The frames are often of
bulb angles with the top of the floor plates flanged over, thus doing
away, with reverse frames. In long, shallow draft vessels, the
hull is strengthened by longitudinal trusses from the floors to the
main deck. Above the main deck there may be several uprights
or posts over which pass rods that are connected to the hull at both
ends to prevent it from sagging. The deck beams may be of bulb
angles with one on every frame. The guard beams should be
bracketed to the sheer strake and secured to the lodger plate in-
stead of the main deck beams extending from outside to outside.
Guard braces may be of trusses, pipe, or solid bars. Sponsons are
required only on the largest steamers.
The machinery of side wheelers varies from the old simple beam
engine to the modern compound and three-cylinder compound
inclined and four-cylinder compound double inclined. The simple
beam engine has great durability, low initial cost and low mainte-
nance. The boilers for this type of engine are of the flue and return
tubular type having a working pressure of around 55 lb., with long
grates, high fire boxes, and simple forced draught, both under and
over the grates. With inclined engines, they have Scotch boilers,
steam 130 to 180 lb., equipped with Howden's forced draught
system. Stern wheelers have horizontal engines (see section on
Marine Engines).
Tugs for ocean towing are preferably of steel, while for harbor
service of wood, as also are lighters. Steam yachts of 150 ft. or
over have steel hulls. Tugs and yachts having steel hulls are
usually built to the rules of a classification society.
Motor Ships. — These are built with steel hulls, classed by Lloyd's
or other society, and engage in foreign and domestic trade. They
are driven by Diesel or semi-Diesel engines, the auxiliaries (winches, ,
Digitized by VjiOOQ 1C
Excursion Vessels, Tugs,
Type of Vessel
Length
Between
Perpendiculars
- Beam
Depth
Draft
Material
of Hull
Carrying
Capacity
Tug *
70' 6*
75' 0* O.A.
18' 8*
7'0*
4' 3*
Wood
109' 0* O.A.
90'0"O.A.
102' or,
23' 0*
20' 0*
20' 7"
11' 3'
9'8»
13' 0*
9'0*
12' 6'
Wood
Wood
Wood
Tug ••••ii to** » *■«.»
....
Tttg -rv*»».r..
119' 6*
130' 0* O.A.
25' 9*
lo'3»
12' 0»
Steel
• «»»
Tug '.
158' 0*
iey o* o.a.
29' 4#
19' 0*
....
Steel
Lighter T
95' 0*
110' 0*
130' 0"
28' 0*
30' 0»
28' V
9'0*
11' 0*
12' V
....
Steel
Steel
Steel
820 tons
Ughtw... .-. T-TTt-f .-•-•- .
450 tone
Day Excursion „ A .
500 pas-
sengers)
Stern Wheel
135' 0*
156' 0* O.A.
23' 4'
4'0*
8'9*
Steel
Western River
Side Wheel Excuraion . .
180' 0*
32' 0*. over
guards. 54' 0*
9'0»
6'0*
Steel
1000
Side Wheel Excursion . .
180' 0*
31' 0» over
guards 53' 0*
WO*
....
Steel
....
Side Wheel Excursion . .
190' 0*
34' 0». over
guards 00' 0*
irr
rv
Wood
2200
j8ide Wheel Excursion .
200' 0»
211'0"O.A.
33' 0*\ over
guards 59' 0*
9/0*
4'0*
Steel
....
8erew passenger. ......
200' 0»
213' 0» Q.A.
35' 0*, over
guards 42' 0*
n' r
WO*
Steel
541st
48 3d
Side wheel passenger. . .
260' 0*
263' 0* O.A.
35' 0*\ over
guards 63' 0'
ll'V
...-
Steel.
....
Steam Yacht
153' 0*
185' 0* OJL
83' if
iro*
Wood
314
Lighters and Steam Yachts
—
I.H.P.
Boilers
Steam,
Lb.
Speed,
Miles
Per
Hour
Remarks.
Twin screw
8 X18
12
total,
300
Water tube: grate sur*
face, 35 sq. ft.; besting
surface, 110 sq. ft.
200
11
Oil burner, 1,700 gal. of oil;
fresh water, 1.300 gab; con-
15 X32
22
450
One 12' dia. by 11' 7"
long: grata, 54 sq. ft.;
besting, 1772
165
12
Condenser, 632 sq. ft. ; wheel,
8'0*dis,byl079*pitoh.
14 xao
20
....
Loco, type: 8' 4* dia.;
13' 0* long; grate, 50
sq. ft.; heating, 1,300
sq.ft.
125
12
Bunker, 20 tons; fresh water,
3.000 gala.; cond.( 550 sq.
ft.; wheel, 7' 4* dia.; 10*
pitch.
1ft X 32
22
138 rev.
580
One— 11' 3* dia. by
12' 8* long; three 36'
furnaces; grate sur-
face, 54 sq. ft.; heat-
ing surface, 1,365 sq. ft.
160
13
Cooling surf see of condenser,
843 sq. ft.; wheel, 8' 0* dia.
by 10' 9* pitch; coal bunker
50 tons; fresh water, 6,900
gallons.
22 X48
36
130 rev.
1250
Two— 14' 6' dia. by
12' long
140
••
Total heating surface of boil-
ers, 4,600 sq. ft.; grate. 168
sq. ft.; condenser, 2,500 sq.
1? X 27 X 45
1100
Two— 13' 0* dia. by.
1' 2* long
175
•-•
Tow 3 barges of a total ca-
pacity of 4,000 tons at 9
knots; bunker, 300 tons.
30
13 X26
18
...w
One boiler 10' 0* dia.
by 10' 0* long
125
••
Surfsce condensing; wheel 6'
9* dia.; 4 blades.
Single 22
....
One boiler 10' 0* dia.
by 16' 0* long
125
-
26
18X36
/ 30
650
Two water tube: heat-
ing surface, 3,350 sq.
ft.; grate, 106 sq.ft.
..-.
-
Weight of boilers and water,
20 tons.
Comp. horiiontsl
12* A 24* by 6'
Stroke
400
Western river type, 3
off, 40* dia. by 28' long
180
10
Stern wheel; Western river*
19' 6* din., by 16' wide, 30
buckets.
Single inclined
25*dia. by V
stroke
600
Two cylindrical, 10'
3* dia. by 10' 0*
long
00
14
Paddle wheels 18' 5* dia., 7'
6* long, 3' wide. Displace-
ment, 480 tons; surface con-
denser. 1,380 sq. ft
8ingle,.42"die,
by UK stroke
\
60
Paddle wheels, 24' din.; coal
bunkers, 25 tons: freshwater,
two tanks, each 750 gallons.
Snsje. 62* dia.
by 97 stroke
1400
Two wagon top
52
19
Paddle wheels, 23' 6* dia.;
llbuekets.
Single. 51* dia.
by 8* stroke
....
One wagon top, 10'
dia. by 27' long
50
Surfsce condensing: wheels,
20' dia.; 35 rev. per min.
18 X 29 X 48
30
1350
Two boilers, 10' 6*
dia. by 12' 9* long
...
15
26 state rooms, river service;
wheel, 10' 6* dia.; 4 blades.
Single cylinder,
55' di*. by 10'
stroke
1800
Two, 9' 6* dia. by
26' 6' long
50
21
Jet condenser.
13HX21 X34
Two water tube: best-
ing surf see, 3,748 sq. ft.
grate surf see, 95 sq. f 1
...
18
Carries 10.000 gsL of water,
100 tons of coat
21
315
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HULL CONSTRUCTION
capstans, etc.) being steam or electric operated. For cost of up-
keep see Internal-Combustion Engines.
Motor Boats. — There are no rules for their scantlings. As to the
hull forms there is the V bottom for cruisers and runabouts where
the cross sections are Vs, and the ordinary curved or round bot-
tom. Hydroplanes have practically flat bottoms with steps, the
hydroplane lifting and running on a step when at full speed. Gaso-
line engines have superseded steam for pleasure craft from 30 to
100 ft., for not only are the former easier to handle, but they take
up less space and a smaller crew is required.
Motor boats over 15 tons come under the supervision of the U. S.
Steamboat-Inspection Service, and are classed as steamboats.
While limited as to carrying capacity motor boats are allowed more
passengers than steamboats of the same size. Their operating
conditions are set forth in their certificates of inspection. In some,
the equipment includes air tanks, under the decks, of sufficient
size to float the boat with her complete complement of passengers
with the hull full of water. Boats over 65 ft. long, carrying freight
for hire are required to have a licensed pilot and engineer.
After January 1, 1915, the U. S. Steamboat-Inspection Service
requires that all ocean steam vessels of over 2,500 gross tons carry-
ing passengers and whose course takes them 200 miles or so off-
shore shall be equipped with not less than one motor-propelled
lifeboat.
See tables of Motor Ships and Motor Boats.
Schooners and Sailing Vessels with Motors. — The schooners in
the following table are typical ones engaging in the coastwise trade
in the United States, the larger sizes trading with South American
countries. The fishing schooners given run out of Boston, Mass.
Schooners generally have wood hulls.
Sailing vessels with motors of the larger sizes are ship rigged,
have steel hulls and engage in the transatlantic or ocean trade.
Many of these vessels are owned by Norwegians.
See Wood Vessels.
Sailing Vessels Fitted with Motors
Length
Breadth
Depth
Deadweight (tons)
Number of Engines
Brake h. p. of each
Total brake h. p
97' 5"
135' 0*
142' 0*
165' 0'
226' 0*
27' 3*
30' 0*
26' 9"
33' 0'
36' 0'
12' 3*
10' 10*
15' 8*
12' 9'
23' 6*
335
500
460
750
1900
1
1
1
1
2
80
160
120
240
120
80
160
120
240
240
308' 2*
42' 8'
26' 10*
3900 J
2
160
320
Bolinder's engines were installed in the above.
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320 HULL CONSTRUCTION
Fishing Schooners Fitted with Motors
Length
Breadth
Depth
Gross tons . . .
Net tons
Engines
Speed
Consumption
~ 96'
100.1'
23.7'
22.7'
11'
9.8'
115
94
79
64
Two 4-cycle each
37.5 h.p.
Two 4-cycle each
37.5 h.p.
7H knots
9 knots
6H gals, of gasoline
7 gals, of gasoline
per hour
per hour
103'
24'
11.8'
141
93
Two 4-cycle each
50 h.p.
8 knots
7}i gals, of gasoline
per hour
MISCELLANEOUS VESSELS
Oil Carriers. — Owing to the extensive use of oil and the finding
of it in many parts of the world, several types of bulk oil carriers
have been developed. Among them may be mentioned: (1) those
with the usual transverse system of framing as per Lloyd's rules
or other classification society; (2) those built on the longitudinal
or Isherwood system; and (3) those built with large cylindrical
tanks with the usual transverse framing modified to suit.
Ships built according to (1) and (2) have a complete subdivision,
there being a longitudinal bulkhead with several transverse.
Lloyd's specify "that oil compartments are not to exceed 24 to 28
ft. in length." As a rule oil carriers are built with the propelling
machinery aft, thus giving the entire forward part of the vessel
for the carrying of oil. In vessels having the machinery aft, a poop
must be fitted of sufficient length to cover the machinery space.
When the engines are amidships the bridge is to be of sufficient
length to overlap the ends of the middle bulkhead in the oil com-
partments. The pump room is often amidships even when the en-
gines and boilers are aft.
Some vessels are designed to have sufficient stability when empty
or with just enough water ballast to give the proper trim, but this
gives a vessel, when loaded, excessive stability and makes her an
uncomfortable roller. In others when the oil is discharged and
they are to proceed again to sea without a cargo it is necessary to
fill several of #ie oil tanks with water to get the desired stability.
This must only be done in port and great care must be taken.
To provide for the expansion and contraction of the oil each com-
partment has an expansion trunk large enough to keep the compart-
ment always full, but with a small free surface so that the fluidity
of the oil will not cause much if any loss of stability. The trunks
are arranged so the surface of the oil will not fall below the sides
nvJ^v^
COFFERDAMS 321
when the vessel is rolling or pitching in a seaway. When the
breadth of the expansion trunk exceeds 60% of the breadth of the
vessel or the height of the trunk exceeds 8 ft. above the top of
the oil compartment, Lloyd's require the plans to be submitted to
their Committee for special approval.
Cofferdams are fitted at the forward and after ends of the oil
space, and when the machinery is amidships they are also fitted
at each end of the machinery space so that the oil cargo will be
isolated from the engine and boiler spaces. The cofferdams must
not be less than two frame spaces in length and must extend from
the keel to the continuous expansion trunk for the full breadth of
the vessel. The cofferdams are practically additional bulkheads
and are connected to the ship's bulkheads by plates and angles.
The best of workmanship is required in the building of oil carriers.
The riveting must be thoroughly oiltight, the spacing never ex^
ceeding 3 or 3H diameters, and the rivet points left full or convex.
The caulking side of the center line bulkhead should be reversed
in each tank and the transverse bulkheads should be caulked on
the forward side in one case and on the after side in the next. This
simplifies testing to a great extent. Portland cement is not re-
quired in compartments where oil is carried.
When cylindrical tanks are installed, these rest on the top of
the tank top, the oil not coming in contact with the hull.
The American Bureau of Shipping recommends that "the three
deck or spar deck type, with the main or second deck forming the
crown of the oil holds and the 'tween-deck be dispensed with.
Furthermore the oil holds are not to exceed 32 ft. in length and
are to be divided by a longitudinal oiltight bulkhead extending
to the top of the expansion trunks connected with all the oil holds.
To provide for the expansion and contraction of the oil, each hold
or compartment is to connect with one or two trunks extending
from the deck forming the crown of the hojds to the deck above."
Some of the latest bulk oil carriers are shelter deckers. y All the
societies insist that vessels carrying oil in bulk be well ventilated,
requiring that efficient means be provided for clearing the com-
partments from dangerous gases by the injection of steam or other
artificial ventilation. •*
Lloyd's Rules state: "Oil fuel the flash point of which by Abel's
close test does not fall below 150° F. may be carried inordinary
cellular double bottoms either under engines or boilers or under
ordinary cargo holds, also in peak tanks or in deep tanks or in oil
bunkers specially constructed for this purpose.
322
HULL CONSTRUCTION
Figure 50. — Pump Installation on Tanker La Brea.
"Cellular double bottoms when fitted for oil fuel are to have
oiltight center divisions and the lengths of these compartments
are to be submitted for approval.
"All compartments intended for carrying oil fuel must be tested
by a head!of water extending to the highest point of the filling pipes,
12 ft. above the load line or 12 ft. above the highest point of. the
compartment, whichever of these is the greatest. r*
"Each compartment must be fitted with an air pipe to be always
open, discharging above the upper deck. It is recommended
Digitized by VjUUv LC
OIL FUEL COMPARTMENTS 323
that all double bottom compartments used for oil fuel should have
suitable holes and doors of approved design fitted in the outer
bottom plating.
"Efficient means must be provided by wells or gutterways, and
sparring or lining to prevent any leakage from any of the oil fuel
compartments from coming into contact with cargo or coal, and to
ensure that any such leakage shall have free drainage into the
limbers or wells.
"If double bottoms under holds are used for carrying oil fuel
the ceiling must be laid on transverse battens, leaving at least 2
ins. air space between the ceiling and tank top, and permitting
free drainage from the tank top into the limbers.
"The pumping arrangements of the oil fuel compartments must
be absolutely distinct from those of other parts of the vessel.
"If it is intended to carry sometimes oil fuel and sometimes
water ballast in any of the compartments, the valves or cocks
connecting the suction pipes to these compartments with the ballast
donkey pump and those connecting them with the oil fuel pump
must be so arranged that the oil may be pumped from any one
compartment by the oil fuel pump at the same time as the ballast
donkey pump is being used on any other compartment.
"All oil fuel suction pipes should have valves or cocks fitted
at the bulkheads where they enter the stoke hold, capable of being
worked both from the stoke hold and from the deck. Valves or
cocks similarly worked are to be fitted to all pipes leading from
the settling or service tanks.
"Oil fuel pipes should, where practicable, be placed above the
stoke hold and engine room plates, and where they are always
visible.
"No wood fittings or bearers are to be fitted in the stoke hold
spaces.
"Where oil compartments are at the sides of or above, or below
the boilers, special insulation is to be fitted where necessary to
protect them from the heat of the boilers, smoke boxes, casings, etc.
"Water service pipes and hoses are to be fitted so that the stoke
hold plates can at any time be flushed with sea water into the
bilges.
"If the oil fuel is sprayed by steam, means are to be provided
to make up for the fresh water used for this purpose.
"If the oil fuel is heated by a steam coil the condensed water
should not be taken directly to the condensers, but should be led
Digitized by VJiOOQlC
324 HULL CONSTRUCTION
into a tank or an open funnel mouth and thence led to the hot well
or feed tank."
* General Notes on Oil Carriers. — Oil in tankers is carried to
the skin of the vessel (except those with cylindrical tanks) and in
many cases no water ballast tanks are below the oil tanks but may
be in the machinery space. Vent pipes must be fitted to the oil
tanks, the tops of the pipes having covers of wire gauze sheets to
prevent sparks or hot cinders from entering the tanks.
The pump room may be forward of the machinery space (which
is usually aft), or it may be amidships with water ballast tanks
below it. In some large steamers there are two pump rooms, one
forward of the machinery space and the other amidships;
The oil pumps are kept entirely separate from the pumps which
fill or clear the water ballast spaces of water, aftid no water ballast
pipe passes through an oil compartment or vice versa. There
are two main lines of suction pipe, one on each side of the center
longitudinal bulkhead. Each line has a suction to each tank on
its own side of the shipt and may have one passing through the longi-
tudinal bulkhead to the corresponding compartment on the other
side. Two valves are fitted to each suction and these are operated
by rods on the weather deck. There are thus two sections in each
compartment and four in each tank, an arrangement which per-
mits both sides of the vessel to be dealt with through the same line
simultaneously. In other cases each line has only one suction on
each side of the center line bulkhead with valves worked from the
upper deck, a master valve being in each line at the bulkheads
also controlled from the upper deck.
When oil is carried in the summer tanks, these may have drop
valves which permit the contents of a tank being drained into
the one immediately below and then discharged through the main
lines. This involves carrying the same quality of oil in the 'tween-
deck spaces as is carried in the corresponding hold space. On
many vessels the summer tanks have an independent line of about
4 ins. diameter.
In emptying the tanks of oil, the pumps will clear the whole of
the cargo in the tanks but will leave the pipe lines full. Ordinarily
this is drained into the end compartment and dealt with by a hand
pump or by buckets.
Steam heating coils are often placed in the tanks, for when heavy
* Abstracts of a pamphlet on "Description and Construction of Oil Steamers" by
J. Montgomerie of Lloyd's.
Digiti
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PIPING ARRANGEMENT 325
viscous oil is carried it is difficult to handle it at ordinary tem-
peratures; in fact a temperature of 120° may be required.
Steam fire extinguishing apparatus is carried by all oil vessels
and provision is made for steaming out the tanks, which may
consist of hoses attached to a steam line on deck. Or, instead, a
system of 6opper pipes with 1 J^-in. branches extend to within a foot
of the bottom of the tanks. In this case the fire extinguishing
and steaming out installations may be combined in one set of pipes,
by having holes cut in the pipes just below the deck.
When general cargo is carried the tanks are ventilated in the
ordinary way by upcast and downcast ventilators, and when oil is
carried the ventilators are closed by blank flanges. Except in
vessels carrying benzine, the tanks are kept as far as possible sealed,
there being only a vapor cock in the side coamings of the hatch-
ways. When benzine is carried vapor pipes of about 2J^ ins.
diameter are connected to the main tanks, and of 2 ins. to the sum-
mer tanks, with cocks at each tank, the pipes being led to one of
about 3 ins. which runs up one of the masts, or there may be two
such pipes.
In some cases after the oil has been pumped out the heavy
air mixed with the gas from the oil is partially removed by opening
the hatches and fixing up a canvas ventilator the bottom of which
extends nearly to the top of the floors. The fresh air entering the
ventilator forces upward the heavy air out through the hatch
openings. Sometimes a fan assists in the movement of the air.
See also Loading and Stowing of Cargoes.
Piping Arrangement. — The following system was installed on
a 410-ft. steamer, the F. H. Buck, having a cargo capacity of 63,900
barrels of oil: "Two duplex pumps having 18 inch steam cylin-
ders, 15 inch oil cylinders with 18 inch stroke. The suction system
consists of two 12 inch mains run one on each side of the center
line bulkhead with a 10 inch branch to each tank. Bypass arrange-
ments are made so that any tank on one side of the ship can be
emptied and discharged either overboard, through seacocks or
into any other tank on the opposite side. Each pump can separately
or together discharge into an 8-inch belt discharge main' running
along the top of the expansion trunk from which 8 inch branches
are fitted for discharging overboard or back to the tanks by 6 inch
branches. Discharges are so arranged that either pump can dis-
charge into one side of the main or the other and division valves
are provided so that one pump can be working at a heavier pressure
Digitized by VjiOOQIC
326
HULL CONSTRUCTION
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LUMBER STEAMERS 327
than the other. An independent 6-inch suction is fitted to one set
of the main cargo tanks to discharge into the fuel tanks. The
discharge system is so arranged that it can be used as suction for
one or both pumps. Each pair of tanks is fitted with a 6-inch
equalizing valve. Two turbine fans are fitted in the* pump room
to discharge air either into the pump room or into 12-inch suction
pipes to the cargo tanks." See Lloyd's Rules above and also
General Notes. A midship section of the F. H. Buck is shown on
page 257.
Lumber Steamers. — These often have only a single deck with a
center longitudinal bulkhead, the machinery being aft. They are
given extra beam, and the main deck is strengthened for carrying
a deck cargo, and special bulwarks built. Cargoes up to 14 ft. in
height may be carried on some steamers. An example of a steamer
designed for the lumber trade is the Wm. O'Brien. She is 361 ft.
between perpendiculars, 51 ft. beam, 27 ft. deep, draft loaded 21
ft. 6 ins., Jumber capacity 3,000,000 ft., single deck, watertight
center line bulkhead entire length of cargo holds from keel to main
deck, machinery aft, 3 single-end Scotch boilers 13 ft. 8 ins. by
m c. c • * ion ik • 24K X 38^ X 67 nn
10 ft. 5 ins., steam 180 lb., engme jr-^ , 90 r. p. m.,
i. h. p. 2,150, speed 11 knots.
Trawlers. — Small steel fishing vessels common in the North Sea
(Europe) built to Lloyd's rules, with machinery aft, thus giving
a large hold forward for carrying fish. They are strongly built
and keep at sea until they have secured a cargo of fish before re-
turning to port. The fish are caught in a large cone-shaped net
that is drawn through the water at a slow speed. A typical trawler
is the following: 130 ft. long, 22 ft. beam, 11 ft. deep, gross ton-
13 X 22 X 36
nage 251, net 171, machinery aft, engine ^= , single
Scotch boiler, steam 150 lb., bunkers 100 tons, speed about 10
knots on 5 tons per 24 hours.
Dredges. — Under this heading is included only those with steel
hulls, ship-shaped, having their own motive power and designed
for dredging channels to sea ports and offshore work. Many of
these dredges are equipped with buckets fastened to an endless
chain, which pick up the material and discharge into hoppers in
the dredge. When the Jioppers are filled the dredge steams out to
sea and there discharges. An example of this type is the King
George, 170 ft. long, 34 ft. beam, 13 ft. 3 ins. deep, steel hull, twin
Digitized by VjOOQ 1C
328 HULL CONSTRUCTION
screw, triple expansion engines each of 600 h. p. •Each engine
can be coupled to the dredging gear. The dredging buckets have
a- capacity of 9 cu. ft. each and are fastened on an endless chain.
There are 32 buckets, with a cast steel body and manganese iron
cutting lips. The rate of travel is about 16 buckets per minute.
Another type is the suction, where the material is drawn from
the bottom through a pipe by means of a powerful centrifugal pump.
Such a dredge is the Balari, 333 ft. long, 54 ft. 6 ins. beam, 22 ft.
3 ins. deep, has a hopper capacity of 71,600 cu. ft. The hull and
machinery are built to Lloyd's highest class. Propelling machinery
consists of two triple expansion engines. There are four large single-
end and horizontal boilers, steam 180 lb. The pumping outfit
placed forward of the hopper in an independent compartment
consists of a tripie expansion engine directly connected to a cen-
trifugal sand pump designed to raise and discharge about 5,000
tons of sand and silt per hour. The pump is connected to a suction
pipe at the bow. The suction end of the pipe is fitted ,with a spe-
cially designed nozzle to suit the character of the material to be
dredged; a grid is fastened to the nozzle to exclude material which
might choke or injure the pump. The suction pipe is controlled
by a steam winch placed on deck. The pumping engine has its
own condenser.
Shallow Draft Steamers, — These may be divided into stern
wheelers and tunnel vessels. The former are extensively used on
the Mississippi River and its tributaries in the United States, also
on South American and African rivers. Those in the United States
have generally wooden hulls with boilers forward and engines aft (see
Marine Engines) . When handling barges they push the barges ahead,
which is the reverse to ocean towing. They often have three or
four rudders placed forward of the stern wheel. The rudders are
given a large area; in fact the immersed area of three rudders aver-
ages from 115 to 150 sq. ft. A typical example is the towboat
Warioto, 141 ft. over all, 120 ft. between perps., 27 ft. beam, depth
at side 5 ft., crown of deck 6 ins., draft with 30 tons of coal on
board 3 ft. 8 ins., displacement about 270 short tons (2,000 lb.),
block coefficient .78, steel hull, 4 watertight transverse bulkheads,
center line bulkhead, 2 longitudinal trusses, 3 boilers, steam 200 lb.,
externally fired, 40 ins. diameter by 24 ft. long, three 9-inch flues,
three 6-inch, grate area 48 sq. ft., heating surface 1,365 sq. ft.,
engine developed 304 i. h. p., 26.9 lb. of steam being required per
i. h. p. per hour for the main and auxiliary engines. In another
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towboat 125 ft. long there were installed two tandem compound
12 X 24
engines — =^ — which weighed complete with condensers and pip-
ing 81,345 lb., and the two boilers, including superheaters, stack,
etc., 94,460 lb. The engines turned a stern wheel 22 to 24 r. p. m.,
18 ft. diameter, buckets 17 ft. long, width 30 ins., 12 arms. Total
weight of wheel 9,380 lb.
Tunnel vessels are driven by propellers running in tunnels, the
propellers being completely surrounded with water. The hulls
may be built of steel plates, that are shipped in sections and are
assembled at their destination. The engines are of the usual
vertical marine type. Below is outlined the Shu Hun, a steamer
built for service on the Yangtse Kiang, China. Hull of steel, length
190 ft., beam 30 ft., draft with cargo of 300 tons 5 ft., 2 doable-end
water tube boilers, supplying steam to two 1,000 h. p. engines.
Another tunnel boat is the following, which was built to run on the
Ob River, Siberia. Length on water line 90 ft., beam 15 ft., depth
5 ft., draft loaded 2 ft. 1J^ ins., steel hull, twin tandem engines each
6^ 8^13^ t0tal h" P' °f b°th at 28° f* P* m' 13°- Jet condensing>
boiler 5 ft. 8 ins. diameter by 12 ft. 4 ins. long, steam 140 lb.
FITTINGS FOR CATTLE AND HORSE STEAMERS.
Weight of Fittings per Head of Cattle Carried.
Cementing on deck 1% ins. thick 185.00 lb.
Total woodwork including bolts 139 . 62
Steel angle footlock clips 11 .43
Castings and fittings 37 . 19
Gnawing strips 6 . 00
Solid cattle stanchions ". 9 . 74
Hollow stanchions 11 . 02
Total per head 400.00 lb.
Sufficient light must be provided for the proper tending of ani-
mals at all times. For ventilating purposes under deck canvas
bags should be fitted to ventilators provided with iron rings at
the bottom, and reaching within 18 ins. of the deck under foot.
Digitized by vjOOQ 1C
PRICES, COSTS AND ESTIMATES
331
Weight of Fittings per Horse Carried.
Cement on deck V/k ins. thick 185.00 lb.
Total woodwork including bolts 273 . 55
Kicking pieces and bolts 34 . 11
Castings and fittings 200.34
Total per horse (London regulation) 693 .00 lb.
Leaving an American port deduct close division
boards 135.00 lb.
Total per horse (American regulation) . . 558.00 lb.
For complete specifications for the requirements for shipping
cattle and horses see U. S. Regulations published by Dept. of
Agriculture.
The cost of fitting, a steamer with stalls averages $8 to $10 per
head under deck and $12 to $15 per head on deck. It is estimated
that the average expense for food for horses and attendants for a
voyage from New York to Liverpool is about $5 a head.
PRICES, COSTS AND ESTIMATES
In Great Britain a fair average price for medium size cargo
steamers in ordinary times is from $40 to $45 a ton per deadweight.
Similar vessels if built in the United States would cost approximately
one and one-half times as much. Below are tables of steamers
sold in May, 1915, and May, 1916. The rise in price being due
to the European war and the demand for tonnage. In general
even the prices quoted in May, 1915, are about 35% above normal.
Steamers Sold in May, 1915
Name D.W. Built Price Rate per ton
Rossia 7,600 1900 £52,000 £6 16
Whitgift 7,350 1901 51,500 7 0
Drumlanrig 7,300 1906 73,000 10 0
Rhodesia 7,200 1900 49,000 6 16
Dongola 7,100 1898 48,500 6 16
Whindyke 6,500 1901 45,000 6 18
St. Fillans 6,400 1900 45,000 7 0
Kalypso 6,000 1904 60,000 10 0
Winnfield 5,800 1901 40,000 6 17
Woolstan 5,400 1900 40,000 7 8
Denaby 5,100 1900 38,000 7 9
Amphitrite 4,400 1897 28,000 6 7
Leafield 4,340 1905 36,000 8 5
Hartburn 3,820 1900 28,000 7 6
Gledhow 3,800 1891 20,000 5 5
Lula 3,600 1890 19,250 $ 6
Digitized by VjiOOQIC
332 HULL CONSTRUCTION
Steamers Sold in May, 1915 — Continued
Name D.W. Built Price Rate per ton
Brynhild 3,450 1899 £30,000 £8 13
Lisl 3,100 1888 18,000 5 15
Girda Ambatiellos 2,755 1888 15,000 5 8
Axminster 2,750 1891 16,500 6 1
Citrine 2,750 1899 25,000 9 1
Karmo 2,300 1882 16,000 6 19
Carmelina 2,300 1904 24,000 10 8
Allan 1,900 1907 26,000 13 13
Rign 1,900 1897 19,000 i0 0
Arena 1,400 1883 12,000 8 11
Roar 950 1904 12,000 12 12
Netta 480 1909 9,000 18 15
Jessie 180 1902 3,000 15 9
Steamers Sold in May, 1916
Name D.W. . Built Price Rate per ton
Daldoreh 7,700 1907 £150,000 £19 9
New Steamer 7,500 1916 180,000 24 0
Globe 7,450 1909 135,000 18 2
Crown 7,335 1906 115,000 15 13
River Forth 7,300 1907 110,000 15 .1
King 7,300 1906 125,000 17 2
Orkedal 6,650 1906 178,000 26 15
Calimeris 6,250 1905 140,000 22 8
Llansannor 6,250 1900 175,000 28 0
Woodbridge 6,060 1900 90,000 14 16
Navarchus Coundouritos. . 5,550 1898 155,000 27 19
Agenoria . . 5,200 1902 70,000 13 9
Huldavore 5,000 1889 100;000 20 0
Zulina 5,000 1899 140,000 28 0
Astarloa 4,500 1896 101,000 22 8
New Steamer 3,500 1916 70,000 20 0
New Steamer 3,300 1916 85,800 26 0
Antonios Embiricos 3,100 1891 62,000 20 0
Sirte 2,900 1887 45,000 15 10
Bizcaya 2,300 1878 41,000 17 16
Harpalys 2,200 1895 33,000 15 0 .
John 1,600 1881 36,250 22 13
Alfred Kreglinger 1,500 1909 37,000 24 13
Alfred Dumois 1,300 1890 13,000 10 0
Artigas 1,100 1911 20,000 18 3
Allerton 830 1914 31,000 37 9
St. Katharine 570 1905 17,500 30 14
Portaferry 240 1884 6,500 27 1
The following are miscellaneous quotations made in the United
States early in 1916.
Coal barge, ship shape, wood hull, 200 ft. long, 32 ft. beam, by
20 ft. deep, new to build $35,000.
Digitized by LiOOQ LC
PRICES ASKED IN 1916 333
Dump scow 120 ft. by 35 ft. by 13 ft., 800 cu. yd., wood, good
condition, but second-hand $4,500.
Deck scow 90 ft. by 27 ft. by 9 ft., good condition, second-hand
$1,000.
Tug, wood hull, 72 ft. long, compound engine, good condition,
second-hand $8,000.
Motor boat 30 ft. long, 15 h. p. engine, new to build $1,500.
Motor yacht 60 ft. long, 35 h. p. engine, new to build $11,000.
Steamer 257 ft. between perpendiculars. 36 ft. 6 ins. beam, 17 ft.
3 ins. deep, single deck, long raised quarter deck with short well
forward, forecastle, machinery amidships, 2,250 tons deadweight
on 16 ft. draft, $225,000, or if machinery aft $190,000. Prices
quoted are to build.
U. S. collier, 13,500 tons displacement, $987,500.
186 ft. O. A., 1,000 tons (Jisplacement, twin screw, single deck
vessel for U. S. Coast and Geodetic Survey, bids ranged from
$163,300 to $266,000.
The prices asked in 19 16 for delivery in New York of the wooden
schooners, particulars of which are given in the table on page 319,
are as follows:
Built
165 ft 1883 $25,000
195 ft 1901 50,000
196 ft 1891 50,000
211 ft 1890 50,000
218 ft x. . . . v 1894 55,000
In comparing the above prices the age and deadweight should
be considered. One yard quoted a price of $80,000 for building a
single deck, 3-mast wooden schooner of 1,200 tons deadweight.
A wooden schooner 260 ft. long on water line, 46 ft. beam, 23.1 ft.
deep, gross tonnage 2,556, net 2,125, built in 1901, sold in New
York in May, 1916, for $195,000. Name of schooner, Rebecca
Palmer.
A round bottom work boat 40 ft. long, 9 ft. beam, having good
lines, with no pilot house, the boat being open with short decks
forward and aft, oak keel, stem, and frames, white cedar planking,
galvanized iron fastenings, cost $1,950. The same size but with
a V bottom cost $1,650, and one 50 ft. by 12 ft. round bottom
cost $3,000 and with a V bottom $2,400. The above prices do
not include motor, fuel tank, or auto top; neither do they include
the installation of the motor, other than a properly constructed
foundation.
Digiti
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334
HULL CONSTRUCTION
Estimates on Building a Motor Schooner on the Pacific
Coast (1916) and of Running her from Seattle, -*.
Wash., to New York*
Dimensions, Equipment and Capacity
Length (custom house) 225' 0*
Breadth 42' 6'
Depth. 18' 0'
Gross tonnage, about 1,250
Net tonnage, about 1,125
Speed, knots, loaded (engine) 7
Lumber capacity 1,500,000 ft. B. M.
Machinery, two oil motors, 160 h. p. each
Cost of the Vessel
Cost of ship complete (wood construction)
Machinery installation
All auxiliary installations
320
$85,000
19,000
18,000
Cost complete $122,000
Design, contracts, supervision at 5% $6,100
Cost of Operating
Crew — Captain $125 per month
First mate 90
Second mate 75
Cook 50
Cabin boy : 20
Eight sailors at $30 240
Chief engineer 100
Assistant 75
$775 X 12
Food, at 68c per man, 15 men for 1 year.
Crew expense per day
$9,300
3,723
$13,023
$35.67
Engine Room Expense
One engine: 160 h. p. X lA lb. oil = 80 lb. per
hour » \i bbl. at 95c per bbl
Lubricating oil at 41c
Fuel and lubricant per hour
Fuel and lubricant, 24 hours
•From Shipping Illustrated, New York.
$0,237
.060
.297
$7.13
Digiti
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OPERATING COSTS OF DIESEL ENGINES 335
Operating cost per day, 2 engines $14 .26
Operating cost per year . 5,204.80
Engine supplies 200.00 $5,404.80
Taxes at V2% 600.00
Depreciation, 5% * 6,100.00
Insurance, 7% 8,540.00
Liability, ty2% 1,830.00
Upkeep and repairs 5,000.00
Total expense per year $40,497 .80
Operating cost per day (ship and engine) 110. 95
Operating cost engine per day 14 .26
Operating ship only per day $96 . 69
To New York with Lumber from Seattle, Wash,
Loading time, 100,000 ft. per day 15 daysv
Expense of ship loading 15 days at —
Captain, mate, engineer, cook. . . $12.00
Food 2.72
Fixed charges per day 60. 47
$75 . 19 X 15 days $1, 107 . 85
Loading, at 85c per M board feet of lumber 1,275.00
Canal charges, $1.20 per net ton 1,350.00
Pilotage, canal 22.00
18 days engines $256.68
36 days ship 3,480.84 $3,737.52
Unloading N. Y., 15 days X 96.69 1,450.35
Unloading, stevedores 1,275.00
$10,217.72
Laid down N. Y. per M board feet $6.81
Operating Costs of Diesel Engines on the Pacific Coast
of the U.'S.
Passenger boat 92 ft. long, 16 ft. beam, 5 ft. draft, driven by
180 h. p. Nlseco Diesel engine, speed 16 miles. Name Suquamish.
The Suquamish ran miles per day 132
Season's mileage, May 1 to Nov. 1 24,300
Season's fuel consumption, gallons 15,000
Cost of fuel oil for season $325 . 13
Digitized by VjiOOQLC
336 HULL CONSTRUCTION
Cost of fuel oil per day of 12}^ hours $1 . 76
Cost of fuel oil per mile lj^c
Cost of repairs, nominal
Tug 70 ft. long, 18 ft. beam, 10 ft. draft, 240 h. p. Nlseco Diesel
engine. Name Chickamauga.
Hours towing 662
Hours running light 188
Total working hours 850
Total fuel consumption, gallons 7725
Total cost of fuel $167.79
Fuel consumption per hour, gallons 9.1
Total cost of fuel per hour 19J£c
Cost of repairs, nominal.
Cannery tender 75 ft. long, 18 ft. beam, 8 ft. draft, 120 h. p.
Nlseco Diesel engine. Name Chomly.
Working time 1489 hrs.
Gallons of fuel consumed 8664
Fuel consumption per hour, gallons 5.8
Price of fuel per barrel 95c
Hourly running cost 13 . lc
Total fuel bill for season $195.97
Cost of repairs $2.00.
Repair Costs of Motor Ships
Name of ship. SembUan London Myer
No. of voyages made . . 90 in 3 years 60 in 20 mos. 2 per month
Total cost of repairs... About $2,400 About $1,600 Nil
Total time lost for re-
pairs Very little Very little Nil
time time
Deadweight capacity . . 300 tons 1750 tons 1750 tons
Horse power 200 1400 1400
Fuel consumption per
geogr. mile 0.02 tons 0.08 tons 0.08 tons
Fuel consumption per
i. h. p. hr 0.16 liter 0.18 liter 0.18 liter
The Diesel engines of the Sembilan, London and Myer were
built at the Werkspoor Works, Amsterdam. The fuel consumption
at sea averaged .30 lb. per i. h. p. hour, compared with 1.20 lb. per
i. h. p. for an oil-fired steamer.
Digitized by VjOOQ LC
COST OF ELECTRIC INSTALLATIONS
.337
Cost of Electric Installations. — Cost of marine generating sets only,
$60 to $80 per kw.
Cost of electric plant complete, including apparatus and in-
stalling:
(Data from Stand. Elect. Engr'a Handbook.)
Type of Vessel
Size of
Generating Set
Lamps
Total
Cost
Tug
3kw.
20 kw.
20 kw.
150 kw.
50
300
150 lamps
searchlight
$1,100
3,000
Ferryboat
Freight steamer
Oil tanker
5,000
7,500
Passenger and freight
steamer
1,200 lamps
searchlight
electric heating
system
27,000
Cost of Refrigerating Systems. — Cork insulation alone on sides,
decks, bulkheads and inner bottom averages about 70 cents per
square foot of surface for an entire compartment. The cost of the
insulation, refrigerating machinery, brine tanks, compressors,
piping, etc., averages for a steamer for carrying frozen or chilled
meat 70 to 75 cents per cubic foot. These prices could be taken
for other products also.
Prices of Steam Engines and Boilers. — The prices of steam engines
alone as given in the table Weights of Engines Alone, page 306,
varied from $1.20 to $1.28 per i. h. p.
Scotch boilers about 10 cents a pound. Water tube boilers as
in the table Weights of Water Tube Boilers, page 308, varied from
23 to 25 cents a pound.
Cost of Fitting up a Steamer for Carrying Cattle, see page 331.
Percentage of Cost of the Parts of a Motor Boat — The following
figures apply to motor boats up to about 100 ft. in length, built
for pleasure purposes and having a speed of around 10 miles an
hour.
Per cent.
Main power plant 24. 2
Power plant accessories 2.4
Electrical equipment 7.5
Miscellaneous equipment 2.7
Finished hull 46.0
Deck equipment 11 .0
Cabin equipment 6.2
Total cost 100.0
338, HULL CONSTRUCTION
The equipment items for a 33-foot raised deck cruiser are as follows'
Main power plant, 20 h. p., 4-cycle motor, magneto, fuel tanks,
piping, etc.
Electrical equipment, running lights, switches, storage battery,
dynamo, and fixtures..
Miscellaneous equipment, charts, marine glasses, navigating
instruments.
Finished hull, planked with 1^-inch cedar, mahogany interior
and cockpit finish, eight built-in lockers, ice box, galley, brass air
ports, bronze rudder and shoe, steering wheel, skylight, signal
mast, ventilators, etc.
Deck equipment, dinghy, life preservers, anchors, moorings,
buoys, etc.
Cabin equipment, cushions, chairs, clock, bedding, rugs, stove,
galley equipment.
Estimates. In preparing a bid on the building of a vessel or on
repair work, the bid should be divided into three parts: (1) the
overhead expenses, (2) the actual cost and (3) the»profi^. In the
overhead is included such items as taxes, insurance, rent, interest
on the money invested, salaries of non-producers as clerks, etc., and
trial trip expenses, preparation of slip, launching ways, etc., directly
charged to the vessel bid on — or if it is a repair job then include
wharfage, water, etc.
The (2) or actual cost includes the cost of the materials and the
time spent by the workman in completing and putting into place
the finished product.
To the overhead expenses and actual cost is added a percentage
for the profit to the yard for undertaking the work. The per-
centage is a variable quantity depending on how close the competi-
tion is and how badly the yard wants the particular contract.
Workmen in shipyards are divided into two classes, viz., piece
workers and hour or day workers. Riveting, putting on shell
plates and other structural work is generally done by piece work —
while the men in the machine shop, outside machinists installing
engines, boilers, etc., are paid by the hour or day. Naval Cons.
W. B. Ferguson, U. S. N., in his book on "Art of Estimating" states —
"If an operation is to be performed by day work, the relative
efficiency of the day workers and of piece workers must be taken
into account in estimating. The cost per day work will average
between 25 and 50% greater than piece work cost under the
ordinary form of management."
Digitized by LiOOQ 1C
MARINE PROPELLING MACHINERY
339
The parts pertaining to the hull are estimated in detail, as the
cost of the raw material of each part, and the labor on it. The
labor can only be closely estimated by making a note of every
operation and the men's time, laying out sheets as the following: —
ESTIMATE SHEET.
Estimate No.
For
Submitted
Date of Estimate
Cost
Delivered
Handling
at
Yard
Labor
Total Cost
Item
Time
(hours)
Rate
Total
Labor
Material
and Labor
All detail figures should be checked by referring to the costs of pre-
vious similar work. In many cases the hull cost can be reduced to a
pound price — and the labor bears a percentage to the cost of the
raw material. .For example, the figures in the table Labor Costs
per Pound are for direct labor cost only for the hull work of four
types of vessels. The labor costs per pound in the table are for
vessels built mostly by day work, and are considerably higher on
the average than would be expected for piece work, bonus or
contract system. The types selected for comparison are all United
States Naval vessels: (1) battleship of New York class, (2) torpedo
boat destroyer of 1,000 tons, (3) collier of Jupiter class and (4)
standard 500-ton Navy coal barge.
Relative Cost of Different Types of Marine Propelling Machinery
Type of Vessel
Description of Machinery
Cost per
1. H. P.
(trial trip)
Cost per
ton of
Finished
Wt.
Steam Up
Lance cargo steamers
Medium cargo steamers . .
Intermediate ocean liners
Medium passenger and
cargo
Twin screw, 3 cylinder, triple
Single screw, 3 cylinder, triple
Twin screw, 4 cylinder, quad. .
Twin screw, and single screw,
3 cylinder, triple
£5.5-£6.5
£5.0-£5.5
£6.25-£7.5
£5.5-£6.26
£27.-£33.
£22 .-£27.
£33.-£39.
£30.-£36.
Table from Marine Eng'g Estimates, C. R. Bruce.
In estimating on the cost of machinery (boilers, engines, etc.)
sheets may be ruled similar to the one for the hull as given above,
so the different parts may be itemized for obtaining the costs of the
raw materials and the labor. Note the following table :
Digitized by VjiOOQIC
340
.HULL CONSTRUCTION
Direct Labor Costs per Pound in Cents*
Items.
&
Ordinary steel in hull
Plating, outer and inner bottoms
Framing
Bulkheads
Decks
Bridges, hammock berthing and cofferdams
Foundations for armor, turrets and guns
Work around secondary battery, etc
Foundations for machinery i
Inclosures •
Metal masts and spars
Rivets
Steel castings and f orgings forming structural parts of hull .
Deck pillars or stanchions
Deck planking and wood in docking and bilge keels
Linoleum, tiling, etc
Joiner work
Carpenter work
Wood ladders
Wood masts and spars
Metal ladders
Pamt, cement, etc
Turret turning machinery, roller tracks and rollers
Fixed ammunition hoist machinery and gear
Rudder and' steering gear
Cranes, davits and other gear for handling boats
Coaling gear v
Pumping and drainage, and sea connections
Plumbing work, including fresh and salt water systems. . . .
Ventilation . . .
Anchor and cable gear
Warping and towing gear
Hand rails and awning stanchions, canopy frames and hatch
cranes
Air ports, deck lights and light boxes
Water tight doors
Non water tight doors ,
Manhole covers, scuttles, etc
Miscellaneous hull fittings
7.7
4.0
7.0
8.0
6.0
15.0
15.0
10.0
15.0
25.0
16.1
12.1
8.0
8.0
30.0
12.0
35.0
25.0
13.4
20.0
13.8
10.0
40.0
25.0
51.0
13.3
15.0
30.0
25.0
44.2
18.1
4f30.
25.0
.3
1.1
1.0
.7
1.1
.6
11.0
1.1
38.0
4.0
2.5
3.0
2.3
0.9
17.1
8.7
16.8
17.2
2.6
13.3
0.8
* From "The Art of Estimating the Cost of Work."
Constructor, U, 8. N.
W. B. Ferguson, Naval
Digiti
zed by G00gk
SECTION VI
MACHINERY
STEAM, FUELS, OIL, BOILERS, MARINE STEAM ENGINES,
STEAM TURBINES, STEAM PLANT AUXILIARIES,
INTERNAL COMBUSTION ENGINES, PIPING,
TUBING, VALVES AND FITTINGS
STEAM
One British Thermal Unit (B. t u.) is the quantity of heat re-
quired to raise the temperature of one pound of water one degree
Fahrenheit when the water is at its greatest density (39.1° F.).
Thus to raise the temperature of one pound of water from 39° to
40° requires one B. t. u., and to raise the temperature of one pound
of boiler feed water from 67° to 212° requires approximately 212 —
67 « 145 B. t. u.
1055 watt-seconds
1 Heat unit (B. t. u.) equals
778 foot-pounds
.000293 kw. hour
.000393 h. p. hour
Calorie (French or Metric Unit of Heat). — One calorie is the
quantity of heat required to raise one kilogram of water one degree
Centigrade. One calorie = 3.968 B. t. u. = 4158.6 watt seconds =
3065 ft. lb. = .0015 h. p. hour. One B. t. u. = .&52 calorie.
Mechanical Equivalent of Heat.
1 B. t. u. = 778 foot-pounds
1 foot-pound = ==£ B. t. u.
Specific Heat of Steam, or the coefficient of its thermal capacity,
is the ratio of the heat required to raise its temperature one degree
to that required to raise the temperature of water one degree
from the temperature of its greatest density, viz., 39.1° F.
Specific heat of saturated steam = . 48
Specific heat of superheated steam = . 77 r
^4-1
342 MACHINERY
Total Heat of Steam (H) is the quantity of heat required to
generate one pound of steam from water at a temperature of 32° F.
to any given temperature and pressure. It is made up of the latent
heat of evaporation and the sensible heat indicated by the ther-
mometer.
Let t = temperature of steam
Then H (total heat of steam) = 1082 + .305 times t
Latent Heat of Steam (L) is the quantity of heat required to trans-
form one pound of water into steam at a given pressure, together
with an amount of heat required to produce the external work
.done by increasing the volume of the water.
internal heat + external heat = latent heat of steam
Then L (latent heat of steam) = 1114 — .7 times tf where t =
temperature of the steam.
In raising the temperature of one pound of water from 67° to
212° F., 145 B. t. u. are required, but after a temperature of 212°
is reached, heat can be imparted to the water until it is all changed
into steam with no increase in temperature, 970.4 B. t. u. being
required for the change in converting one pound of water at 212°
into one pound of steam at atmospheric pressure. The value
970.4 B. t. u. is known as the latent heat of steam or the heat
of vaporization of steam at 212°. Some authorities, instead of
using 970.4, use 966. Thus to change or evaporate into steam
one pound of water at 212° requires 970.4 (or 966) units of
heat.
Efficiency of the Steam in an engine is the ratio of the work
done on the pistons in a given time (as measured by indicator
diagrams) to the energy contained in the steam passing to the en-
gine during the same time. In good modern engines using from
14 to 18 lb. of steam per i. h. p. per hour, this corresponds with
steam efficiencies of 16 J^ to 12 H%-
Steam Consumption per 1. h. p. in condensing engines averages
about 13.65 lb.
Type of Engine
Pounds of Steam
per i. h. p. per
Hour
Single non-condensing
30
Single condensing
20
Compound condensing
15
Triple expansion condensing
12
y Google
KINDS OF STEAM 343
(See tables under Turbines; also under Marine Engines.)
Kinds of Steam. — Saturated steam is steam of the temperature
due to its pressure — not superheated. y
Superheated steam is steam heated to a temperature above that
due to its pressure. The advantages claimed are fuel economy,
water economy, and consequently increased carrying capacity of
the vessel. Superheated steam is more common in Europe than
in the United States. The degree of superheat may be divided as
follows: low from zero to 50° F.; moderate 50° to 125°; and high
125° and upwards. Generally with turbines working at a pressure
of 175 to 200 lb. there is a saving in steam consumption of about
one per cent, for each 10° of superheat — which is true for recipro-
cating engines also. In a test made on a triple expansion engine,
with an average superheat of 85° at the engine, there was a saving
in the coal of about 9% (see table under Superheaters). With
superheated steam the pipe lines and fittings should be of steel
and cast steel respectively. Other materials as copper and bronze
lose their strength in high temperatures and should be avoided in
piping and fittings for highly superheated steam. As to the engine
valves the high pressure cylinder valve should be of the piston
type, preferably with an inside admission. For equal engine
power the cut-off with superheated steam must be somewhat in-
creased above that for saturated steam.
Superheated steam is greater in volume than saturated steam
of the same pressure. Linde's equation is
p v - .5962 T - p (1 + .0014 p) ^l50^000 _ .0833^
where p = pressure in pounds per square inch,
v = volume in cubic feet,
T = absolute pressure.
The table on page 344 from Peabody's Steam Tables gives the
mean specific heat of superheated steam from the temperature of
saturation to various temperatures at several, pressures.
Thus the mean specific heat of steam at 142.2 lb. pressure when
superheated to 572° F. is .53. The heat required to raise one
pound of steam from a saturation temperature of 354° to 572° is
(572 - 354) .53 » 115.5 B. t. u. The total heat of the super-
heated steam is the sum of this quantity and the heat in the satu-
rated steam. See also Superheaters.
Dry steam is steam that contains no moisture.
Wet steam is steam containing intermingled moisture, mist or
Digitized by VjiOOQIC
344
MACHINERY
Kilograms
per square
1
2
4
6
8
10
12
14
16
18
20
centimeter
Pounds per
square inch
14.2
28.4
56.9
85.3
113.8
142.2
170.6
199.1
227.5
256.0
284.4
Temp.
»
saturation
99
120
143
158
169
179
187
194
200
206
211
°C.
Temp.
saturation
°F.
210
248
289
316
336
354
369
381
392
403
412
op
°C.
212
100
.463
302
150
.462
.478
.515
392
200
.462
.475
.502
.530
.560
.597
.635
.677
482
250
.463
.474
.495
.514
.532
.552
.570
.588
.609
.635
.664
572
300
.464
.475
.492
.505
.517
.530
.541
.550
.561
.572
.585
662.
350
.468
.477
.492
.503
.512
.522
.529
.536
.543
.550
.557
752
400
.473
.481
.494
.504
.512
.520
.526
.531
.537
.542
.547
spray. It has the same temperature as dry saturated steam of
the same pressure.
Miscellaneous Notes. — The temperature of steam in contact
with water depends upon the pressure under which it is generated.
At the ordinary atmospheric pressure (14.7 lb. per square inch) its
temperature is 212° F. As the pressure is increased, as by the
steam being generated in a closed vessel, its temperature and that
of the'water in its presence increases.
Absolute zero is taken by different authorities as being from
459.2° to 460.66° below the Fahrenheit zero. The value, 460°, is
close enough for all engineering calculations.
Steam Table. — The following table contains the properties of
dry saturated steam. Column 1 gives the absolute pressure of the
steam in pounds per square inch, the gauge pressure being 14.7 lb.
less. Column 2 gives the corresponding temperature of the, steam
in Fahrenheit degrees. Column 3 gives the heat of the liquid, or
the heat necessary to raise one pound of water from 32° to the
boiling point corresponding to the pressure. Column 4 gives the
latent heat, or the heat necessary to change a pound of water at
the temperature of the boiling point into steam at the same temper-
ature. Column 5 gives the total heat of the steam, and is the
sum of the quantities in Column 3 and Column 4. Column 6 is
the volume of one pound of steam at the different temperatures.
Column 7 is the weight of one cubic foot of steam at the different
temperatures.
Properties of Saturated Steam
Abs.
Pressure
Temper-
ature
Degrees
Heat
Latent
Heat
Total
Specific
Volume
Density
Pounds
Abs.
Pressure
Pounds
of the
of
Heat of
Cu. Ft.
Pounds
per
Sq. In.*
Liquid
Evapora-
tion
Steam
per
Pound
per
Cu. Ft.
per
Sq. In.
P
t
h
L
H
V
_i
V
P
.0886
32
0
1072.6
1072.6
3301.0
.000303
.0886
.2562
60
28.1
1057.4
1085.5
1207.5
.000828
.2562
.5056
80
48.1
1046.6
1094.7
635.4
.001573
.5056
1
101.8
69.8
1034.6
1104.4
333.00
.00300
1
2.
126.1
94.1
1021.4
1115.5
173.30
.00577
2 .
3
141.5
109.5
1012.3
1121.8
118.50
.00845
3
4
153.0
120.9
1005.6
1126.5
90.50
.01106
4
5
162.3
130.2
1000.2
1130.4
73.33
.01364
5
6
170.1
138.0
995.7
1133.7
61.89
.01616
6
7
176.8
144.8
991.6
1136.4
53.58
.01867
7
8
182.9
150.8
988.0
1138.8
47.27
.02115
8
9
188.3
156.3
984.8
1141.1
.42.36
.02361
9
10
193.2
161.2
981.7
1142.9
38.38
.02606
10
11 -
197.7
165.8
978.9
1144.7
35.10
.02849
11
12
202.0
170.0
976.3
1146.3
32.38
.03089
12
13
205.9
173.9
973.9
1147.8
30.04
.03329
13
14
209.6
177.6
971.6
1149.2
28.02
.03568
14
14.7
212.0
180.1
97Q.0
1150.1
26.79
.03733
14.7
15
213.0
181.1
969.4
1150.5
26.27
.03806
15
16
216.3
184.5
967.3
1151.8
24.77
.04042
16
17
219.4
187.7
965.3
1153.0
23.38
.04277
17
18
222.4
190.6
963.4
1154.0
22.16
.04512
18
19
225.2
193.5
961.5
1155.0
21.07
.04746
19
20
228.0
196.2
959.7
1155.9
20.08
.04980
20
21
230.6
198.9
958.0
1156.9
19.18
.05213
21
22
233.1
201.4
956.4
1157.8
18.37
.05445
22
23
235.5
203.9
954.8
1158.7
17.62
.05676
23
24
237.8
206.2
953.2
1159.4
16.93
.05907
24
25
240.1
208.5
951.7
1160.2
16.30
.0614
25
26
242.2
210.7
950.3
1161.0
15.71
.0636
26
27
244.4
212.8
948.9
1161.7
15.18
.0659
27
28
246.4
214.9
947.5
1162.4
14.67
.0682
28 .
29
248.4
217.0
946.1
1163.1
14.19
.0705
29
30
250.3
218.9
944.8
1163.7
13.74
.0728
30
31
252.2
220.8
943.5
1164.3
13.32
.0751
31
32
254.1
222.7
942.2
1164.9
12.93
.0773
32
33
255.8
224.5
941.0
1165.5
12.57
.0795
33
34
257.6
226.3
939.8
1166.1
12.22
.0818
34
35
259.3
228.0
938.6
1166.6
11.89
.0841
35
36
261.0
229.7
937.4
1167.1
11.58
.0863
36
37
262.6
231.4
936.3
1167.7
11.29
.0886
37
38
264.2
233.0
935.2
1168.2
11.01
0908
38
39
265.8
234.6
934.1
1168.7
10.74
.0931
39
40
267.3
236.2
933.0
1169.2
10.49
.0953
40
41
268.7
237.7
931.9
1169.6
10.25
.0976
41
42
270.2
239.2
930.9
1170.1
10.02
.0998
42
43
271.7
240.6
929.9
1170.5
9.80
.1020
43
44
273.1
242.1
928.9
1171.0
9.59
.1043
44
45
274.5
243.5
927.9
1171.4
9.39
.10C5
45
46
275.8
244.9
926.9
1171.8
9.20
.1087
46
47
277.2
246.2
926.0
1172.2
9.02
.1109
47
48
278.5
247.6
925.0
1172.6
8.84
.1131
48
49
279.8
248.9
924.1
1173.0
8.67
.1153
49
50
281.0
250.2
923.2
1173.4
8.51
1175
50
51
282.3
251.5
922.3
1173.8
8.35
1197
51
52
283.5
252.8
921.4
1174.2
8.20
.1219
52
53
284.7
254.0
920.5
1174.5
8.05
.1241
53
* To get the gauge pressure subtract 14.7 lbs. from the absolute.
345
Google
Properties of Saturated Steam — Continued
Aba.
Pressure
Temper-
ature
Degrees
F.
Heat
Latent
Heat
Total
Specific
Volume
Density
Pounds
Abs.
Pressure
Pounds
of the
of
Heat of
Cu. Ft.
Pounds
per
Liquid
Evapora-
Steam
per
per
Cu. Ft.
„***?
Sq. Im
tion
Pound
Sq. In.
V
t
h
L
H
V
V
P
54
285.9
255.2
919.6
1174.8
7.91
.1263
54
55
287.1
256.4
918.7
1175.1
7.78
.1285
55
56
288.2
257.6
917.9
1175.5
7.65
.1307
56
57
289.4
258.8
917.1
1175.9
7.52
.1329
57
58
290.5
259.9
916.2
1176.1
7.40
.1351
58
59
291.6
261.1
915.4
1176.5
7.28
.1373
59
60
292.7
262.2
914.6
1176.8
7.17
.1394
60
61
293.8
263.3
913.8
1177.1
7.06
.1416
61
62
294.9
264.4
913.0
1177.4
6.95
.1438
62
63
295.9
265.5
912.2
1177.7
6.85
.1460
63
64
297.0
266.5
911.5
1178.0
6.75
.1482
64
65
298.0
267.6
910.7
1178.3
6.65
.1503
65
66
299.0
268.6
910.0
1178.6
6.56
.1525
.66
67
300.0
269.7
909.2
1178.0
6.47
.1547
67
68
301.0
270.7
908.4
1179.1
6.38
.1569
68
69
302.0
271.7
907.7
1179.4
6.29
.1591
69
70
302.9
272.7
906.9
1179.6
6.20
.1612
70
71
303.9
273.7
906.2
1179.9
6.12
.1634
71
72
304.8
274.6
905.5
1180.1
6.04
.1656
72
73
305.8
275.6
904.8
1180.4
5.96
.1678
73
74
306.7
276.6
904.1
1180.7
5.89
.1699
74
75
307.6
277.5
903.4
1180.9
5.81
.1721
75
76
308.5
278.5
902.7
1181.2
5.74
.1743
76
77
309.4
279.4
902.1
1181.5
5.67
.1764
77
78
310.3
280.3
901.4
1181.7
5.60
.1786
78
79
311.2
281.2
900.7
1181.9
5.54
.1808
79
80
312.0
282.1
900.1
1182.2
" 5.47
.1829
80
81
312.9
283.0
899.4
1182.4
5.41
.1851
81
82
313.8
283.8
899.8
1182.6
5.34
.1873 .
82
83
314.6
284.7
898.1
1182.8
5.28
.1894
83
84
315.4
285.6
897.5
1183.1
5.22
.1915
84
85
316.3
286.4
896.9
1183.3
5.16
.1937
85
86
317.1
287.3
896.2
1183.5
5.10
. 1959
86
87
317.9
288.1
895.6
1183.7
5.05
.1980
87
88
318.7
288.9
895.0
1183.9
5.00
.2002
88
89
319.5
289.8
894.3
1184.1
4.94
.2024
89
90
320.3
290.6
893.7
1184.3
4.89
.2045
90
91
321.1
291.4
893.1
1184.5
4.84
.2066
91
92
321.8
292.2
892.5
1184.7
4.79
.2088
92
93
322.6
293.0
891.9
1184.9
4.74
.2110
93
94
323.4
293.8
891.3
1185.1
4.69
.2131
94
95
324.1
294.5
890.7
1185.2
4.65
.2152
95
96
324.9
295.3
890.1
1185.4
4.60
.2173
96
97
325.6
296.1
889.5
1185.6
4.56
.2194
97
98
326.4
296.8
889.0
1185.8
4.51
.2215
98
99
327.1
297.6
888.4
1186.0
4.47
.2237
99
100
327.8
298.4
887.8
1186.2
4.430
.2257
100
101
328.6
299.1
887.2
1186.3
4.389
.2278
101
102
329.3
299.8
886.7
1186.5
4.349
.2299
102
103
330.0
300.6
886.1
1186.7
4.309
.2321
103
104
330.7
301.3
885.6
1186.9
4.270
.2342
104
105
331.4
302.0
885.0
1187.0
4.231
.2364
105
106
332.0
302.7
884.5
1187.2
4.193
.2385
106
107
332.7
303.4
883.9
1187.3
4.156
.2407
107
108
333.4
304.1
883.4
1187.5
5.119
.2428
108
109
334.1
304.8
882.8
1187.6
4.082
.2450
109
110
334.8
305.5
882.3
1187.8
4.047
.2472
110
346
y Google
Properties of Saturated Steam — Continued
Abs.
Pressure
Temper-
Heat
Latent
Heat
Total
Specific
Volume
Density-
Pounds
Abs.
Pressure
Pounds
ature
Degrees
of the
of
Heat of
Cu. Ft.
Pounds
per
Liquid
Evapora-
Steam
per
per
Cu. Ft.
per
Sq. In.
tion
Pound
Sq. In.
P
t
h
L
H
V
±
V
P
111
335.4
306.2
881.8
1188.0
4.012
.2493
111
112
336.1
306.9
881.2
1188.1
3.977
.2514
112
113
336.8
307.6
880.7
1188.3
3.944
.2535
113
114
337.4
308.3
880.2
1188.5
3.911
2557
114
114.7
337.9
308.8
879.8
1188.6
3.888
.2572
114.7
115
338.1
309.0
879.7
1188.7
3.878
.2578
115
116
338.7
309.6
879.2
1188.8
3.846
.2600
116
117
339.4
310.3
878.7
1189.0
3.815
.2621
117
118
340.0
311.0
878.2
1189.2
3.784
.2642
118
119
340.6
311.7
877.6
1189.3
3.754
.2663
119
120
341.3
312.3
877.1
1189.4
3.725
2684
120
121
341.9
313.0
876.6
1189.6
3.696
2706
121
122
342.5
313.6
876.1
1189.7
3.667
2727
122
123
343.2
314.3
875.6
1189.9
3.638
2749
123
124
343.8
314.9
875.1
1190.0
3.610
2770
124
125
344.4
315.5
874.6
1190.1
3.582
.2792
125
126
345.0
316.2
874.1
1190.3
3.555
.2813
126
127
345.6
316.8
873.7
1190.5
3.529
.2834
127
128}
346.2
317.4
873.2
1190.6
3.503
.2855
128
129 :
346.8
318.0
872.7
1190.7
3.477
.2876
129
130
347.4
318.6
872.2
1190.8
3.452
.2897
130
131
348.0
319.3
871.7
1191.0
3.427
.2918
131
132
348.5
319.9
871.2
1191.1
3.402
.2939
132
133
349.1
320.5
870.8
1191.3
3.378
.2960
133
134
349.7
321.0
870.4
1191.4
3.354
.2981
134
135
350.3
321.6
869.9
1191.5
3.331
.3002
135
136
350.8
322.2
869.4
1191.6
3.308
.3023
136
137
351.4
322.8
868.9
1191.7
3.285
.3044
137
138
352.0
323.4
868.4
1191.8
3.263
.3065
138
139
352.5
324.0
868.0
1192.0
3.241
.3086
139
140
353.1
324 5
867.6
1192.1
3.219
.3107
140
141
353.6
325.1
867.1
1192.2
3.198
.3128
141
142
354.2
325.7
866.6
1192.3
£.176
3.155
.3149
142
143
354.7
326.3
866.2
1192.5
3170
143
144
355.3
326.8
865.8
1192 6
3.134
.3191
144
145
355.8
327.4
865 3
1192.7
3.113
.3212
145
146
356.3
327.9
864.9
1192.8
3.093
.3233
146
147
356.9
328.5
864.4
1192.9
3.073
.3254
147
148
357.4
329.0
864.0
1193.0
3.053
.3275
148
149
357.9
329.6
863.5
1193.1
3.033
3297
149
150
358.5
330.1
863 1
1193.2
3.013
.3319
150
152
359.5
331.2
862.3
1193.5
2 975
.3361
152
154
360.5
332.3
861.4
1193.7
2 939
.3403
154
156
361.6
333.4
860.5
1193.9
2.903
.3445
156
158
362.6
334.4
859.7
1194.1
2.868
3487
158
160
363.6
335.5
858.8
1194.3
2.834
3529
160
162
364.6
336.6
858.0
1194.6
2 801
.3570
162
164
365.6
337.6
857.2
1194.8
2.768
.3613
164
166
366.5
338.6
856.4
1195.0
2.736
3655
166
168
367.5
339.6
855.5
1195.1
2.705
.3697
168
170
368.5
340.6
854.7
1195.3
2.674
.3739
170
172
369.4
341.6
853.9
1195.5
2.644
.3782
172
174
370.4
342.5
853.1
1195.6
2.615
.3824
174
176
371.3
343.5
852.3
1195.8
2.587
3865
176
178
372.2
344.5
851.5
1196.0
2 560
.3907
178
180
373.1
345.4
850.8
1196.2
2.532
.3949
180
182
374.0
346.4
850.0
1196.4
2.506
.3990
182
347
y Google
Properties of Saturated Steam — Concluded
Abs.
Pressure
Temper-
ature
Degrees
F.
Heat
Latent
Heat
Total
Specific
Volume
Density
Pounds
Abs.
-'ressure
Pounds
of the
of
Heat of
Cu. Ft.
Pounds
per
Liquid
Evapora-
Steam
per
per
Cu. Ft.
per
Sq. In.
tion
Pound
Sq. In.
P
t
h
L
H
t
±
9
P
184
374.9
347.4
849.3
1196.7
2.480
.4032
184
186
375.8
348.3
848.5
1196.8
2.455
.4074
186
188
376.7
349.2
847.7
1196.9
2.430
.4115
188
190
377.6
350.1
847.0
1197.1
2.406
2.381
.4157
190
192
378.5
351.0
846.2
1197.2
.4200
192
194
379.3
351.9
845.5
1197.4
2.358
.4242
194
196
380.2
352.8
844.8
1197.6
2.335
.4284
196
198
381.0
353.7
844.0
1197.7
2.312
.4326
198
200
381.9
354.6
843.3
1197.9
2.289
.4370
200
202
382.7
355.5
842.6
1198.1
2.268
.4411
202
204
383.5
356.4
841.9
1198.3
2.246
.4452
204
206
384.4
357.2
841.2
1198.4
2.226
.4493
206
208
385.2
358.1
840.5
1198.6
2.206
.4534
208
210
386.0
358.9
839.8
1198.7
2.186
.4575
210
212
386.8
359.8
839.1
1198.9
2.166
.4618
212
214
387.6
360.6
838.4
1199.0
2.147
.4660
214
216
388.4
361.4
837.7
1199.1
2.127
.4700
216
218
389.1
362.3
837.0
1199.3
2.108
.4744
218
220
389.9
363.1
836.4
1199.5
2.090
.4787
220
222
390.7
363.9
835.7
1199.6
2.072
.4829
222
224
391.5
364.7
835.0
1199.7
2.054
.4870
224
226
392.2
365.5
834.3
1199,8
2.037
.4910
226
228
393.0
366.3
833.7
1200.0
2.020
.4950
228
230
393.8
367.1
833.0
1200.1
2.003
.4992
230
232
394.5
367.9
832.3
1200.2
1.987
.503
232
234
395.2
368.6
831.7
1200.3
1.970
.507
234
236
396.0
369.4
831.0
1200.4
1.954
.511
236
238
396.7
370.2
830.4
1200.6
1.938
.516
238
240
397.4
371.0
829.8
1200.8
1.923
.520
240
242
398.2
371.7
829.2
1200.9
1.907
.524
242
244
398.9
372.5
828.5
1201.0
1.892
.528
244
246
399.6
373.3
827.8
1201 . 1
1.877
.532
246
248
400.3
374.0
827.2
1201.2
1.862
.537
248
250
401.1
374.7
826.6
1201.3
1.848
.541
250
275
409.6
383.7
819.0
1202.7
1.684
.594
275
300
417.5
392.0
811.8
1203.8
1.547
.647
300
350
431.9
407.4
798.5
1205.9
1.330
.750
350
Above table from Steam Tables, by Prof. C. H. Peabody. Definitions and for-
mulae include abstracts from Prac. Marine Eng'g and Oil Fuel.
Volume of Steam. — If water at boiling point (212° F) is evaporated
into steam at atmospheric pressure, the volume of the steam will be
1577 times the volume of the water from which it was evaporated.
Or one cubic inch of water will produce nearly one cubic foot (1728
cu. ins.) of steam.
348
Digiti
zed by G00gk
COAL CONSUMPTION 349
Pounds or Gallons of Water Evaporated into Dry Steam per
Pound of Coal. — Eight to ten pounds of water can be evaporated
in well-designed boilers with good draft for every pound of bitumi-
nous coal used.
Example. The temperature of the feed water is 110°, the steam pressure
150 lb., the thermal value of the coal used is 14,000 B. t. u. per pound, apd the
efficiency of the boiler is .64. Find the pounds of water evaporated into dry
steam per pounds of coal.
From the steam tables the heat in the water at 212° at a pressure of 150 lb.
gauge or 164.7 absolute (150 + 14.7) - 338
Heat in the feed water (110° - 32°) = 78
260 difference
Latent heat of steam at 164.7 lbs. = 857
Then heat required per pound of dry steam =1117.
The heat available per pound of coal = .64 (efficiency of boiler) X 14,000
8960
B. t. u. = 8960. Hence pounds of steam evaporated = -- « 8.03.
To convert 8.03 lb. of water into U. S. gallons divide by 8.33, as one U. S. gallon
weighs 8.33 lb.
o no
Thus |^ = .96 gallon
o.oo
Pounds of Coal Required to Evaporate One Pound or One Gallon
of Water into Steam.
Let T = steam temperature, and t = feed water temperature
Then units of heat = 1115 + .3 {T - t)
Example. The steam pressure in a Scotch boiler is 160 lb. and the tempera-
ture 370°. The feed water temperature is 140°. Find the units of heat required
to evaporate one pound of water into steam, and the number of pounds of water
evaporated by one pound of coal.
Units of heat required per pound of coal = 1115 + .3 (370° — 140°) = 1086.
Assume that one pound of coal gives out 9,000 units of heat (B. t. u.)
9000 *
Then -r~^ -= 8.28 lb. of water or .99 gallon are evaporated per pound of coal.
Coal Consumption. — The coal required per indicated horse power
per hour in good practice is between 1.5 to 2.0 lb.
Let C = pounds of coal per i. h. p. per hour
ff - i. h. p.
C X H = pounds of coal per hour
C XH
tons of coal per hour
24 XCXH CXH
2240
Then tons of coal per day of 24 hours =
2240 93.3
Formulae from Prac. Marine Eng'g and Verbal Notes, J. W. M. Sothera.
360 MACHINERY
As a quick estimate it may be assumed that a coal consumption
of 1.S6 lb. per i. h. p. per hour (a figure only moderately good) the
coal consumed per day will be 20 tons per 1000 i. h. p. See Marine
Engines, paragraph To Calculate the Coal Consumption per i. h. p.
Example. How many tons of coal will be required in the bunkers of a ship
making a 7-day trip, with a coal consumption of 1.78 lb. per i. h. p., the engines
being of 2,400 i. h. p., and a margin of 10% being allowed for emergencies.
~ , j r i 24XCXH 3X1.78X2400 ,B„-A
Coal per day using formula — ^oln ~ 280 "*
Coal for 7 days - 7 x 45.77 = 320 tons
Margin 10% = 32
352 tons required
The rate of combustion in a furnace is computed by the pounds
of fuel consumed per square foot of grate surface per hour. In gen-
eral practice the rate for natural draft for anthracite coal is from
7 to 16 lb., for bituminous from 10 to 25 lb., and with artificial
or forced draft as by a blower, exhaust blast, or steam jet, the
rate may be increased from 30 to 120 lb. Consumption of fuel
averages 7K lb. of coal or 15 lb. dry pine wood per cubic foot of
water evaporated.
Fuel (Coal or Oil) Consumption* may be said to vary approx-
imately as the horse power developed. The horse power varies
as the cube (within certain limits) of the speed, hence it follows
that the fuel consumption will vary approximately as the cube of
the speed.
Let S = certain speed of vessel
C — coal or oil consumption at speed S
8 — new speed
c = coal or oil consumption at speed a
m. «* X C A A*/c X £»
Then c = — ™ — and s = y — ^ -
Example. A steamer consumes 100 tons of coal per day a\> a speed of 10 knots.
What should be her speed if the Goal consumption were cut down to 50 tons a day.
TT. .u r , //0<fS» */50 X 103
Using the formula s = Af — jj— = A/ — =■== — = 7.9 knots
Evaporation per Pound of Combustible. — It is often necessary
to make an allowance for ash in the coal, or for the ash and mois-
ture, so as to obtain the evaporation per pound of actual com-
bustible matter. This is obtained by dividing the evaporation
per pound of coal by the fraction of the coal which is combustible.
* From Mariner's Handbook.
Digitized by LiOOQ 1C
HEAT VALUES OF COAL
351
The average multi-tubular boiler with coal evaporates 9 to 11
lb. of water per pound of coal. With oil it evaporates 15 to 16.5 lb.
of water per pound of oil. (See Factor of Evaporation.)
3K to 4 barrels of oil are equivalent in boiler evaporation to
one ton of coal. The average barrel of oil holds 50 to 51 gallons.
See Oil
Heat Values of Coal. — In anthracite coal the proportion of
volatile matter varies from 3 to 10%, in semi-anthracite and semi-
bituminous from 10 to 20%, and in bituminous from 20 to 50%.
The amount of ash in good coal should not exceed 8 or 10%, although
occasionally it is only 5%.
Coal
Fixed
Carbon
Volatile
Matter
B. t. u. per
Pound
of
Combustible
B. t.u.
per
Pound of
Coal
Anthracite, Pennsylvania, average
84.25%
51.17%
73.65%
5.62%
34.04%
18.30%
14113
14948
15682
12685
Bituminous, Pennsylvania average
of 28 samples
Pocahontas (West Virginia
13634
14419
From Oil Fuel.
Calorific Value of Coal from its Chemical Analysis. — B. t. u. per
pound of coal = 14600 C + 62000 (h - ^\ + 4000 S
Where C, Hy O and S are the proportionate parts by weight of
carbon, hydrogen, oxygen and sulphur. Take for example a coal
of the following composition (Pocahontas run of mine) : C = 85.4%,
H = 4.39%, 0 = 3.94%, S - 0.62%.
Then B. t. u. per lb. = 14600 X .854 4- 62000 (.0439- -^jp) +
4000 X .006 = 14910.
As tested by a calorimeter this coal had actually a calorific value
of 14906. The above formula is recommended by the American
Society of Mechanical Engineers.
Size of Coal
Anthracite coal is graduated commercially as follows:
Lump over bars set 3J^ to 5 ins. apart.
Steamboat over 3J^-inch mesh and out of screen
Broken over 2%-inch mesh, through 3j^-inch mesh
Egg over 2 -inch mesh, through 2J£-inch mesh
Stove over 1%-inch mesh, through 2 -inch mesh ,
Digitized by VjiOOQIC
352 MACHINERY
Chestnut over %-inch mesh, through 1%-inch mesh
Pea - over }^-inch mesh, through %-inch mesh
Buckwheat over %-inch mesh, through J^-inch mesh
Rice over A-inch mesh, through J^-inch mesh
Culm, slack, or screenings through A-inch mesh.
Bituminous or soft coal is graduated as follows:
Run of mine in fine and large lumps.
Lump or Block goes through 6-inch screen or over.
Egg goes over 3-inch mesh, through 6-inch
No. 1 Roller Screened Nut over 2-inch mesh, through 3J^-inch
No. 2 Roller Screened Nut over 13^-inch mesh, through 2-inch
No. 3 Roller Screened Nut over 1-inch mesh, through lj^-inch
No. 1 Washed Egg over 2-inch mesh, through 3-inch
No. 2 Washed Stove over l}£-mch mesh, through 2-inch
No. 3 Washed Chestnut over %-inch mesh, through lj^-inch
No. 4 Washed over J^-inch mesh, through %-inch
No. 1 Domestic Nut over 1 J^ or 2-inch mesh, through 3-inch
No. 2 Nut over IJ^-inch mesh, through 2-inch
No. 3 over jj-inch mesh, through 1 J^-inch
Duff through J^-inch mesh.
Screenings smallest sizes.
Pocahontas Smokeless generally sized as Nut, Egg, Lump and
Mine Run.
Heat Values of Wood. — The average heat value of dry wood
is 8,500 B. t. u. per pound, for wood with 25% moisture 6,000 B. t. u.
and for 40% moisture 4,600.
One Cord Air Dried Hickory or Hard Maple weighs about 4,500
lb. and is equal to about 2,000 lb. coal.
One Cord Air Dried White Oak weighs about 3,850 lb., and is
equal to about 1,715 lb. coal.
One Cord Air Dried Beech, Red Oak and Black Oak weighs about
3,250 lb., and is equal to about 1,450 lb. coal.
One Cord Air Dried Poplar (whitewood), Chestnut and Elm
weighs about 2,250 lb., and is equal to about 1,050 lb. coal.
One Cord Air Dried Average Pine weighs about 2,000 lb., and is
equal to about 825 lb. coal.
From the above it is safe to assume that 2\i lb. of dry wood is
equal to 1 lb. average quality of soft coal, and that the full value
of the same weight of different woods is very nearly the same — that
is, a pound of hickory is worth no more for fuel than a pound of pine,
assuming both to be dry. It is important that the wood be dry,
as each 10% of water or moisture in wood will detract about 12%
from its value as fuel. (Cord of wood a pile 4 ft. X 4 ft. X 8 ft.)
Heat Value of Oil, see section on Oil.
Digitized by LiOOQ 1C
OIL
353
Temperature of Fire. — The following table from M. Pouillet
will enable the temperature to be judged by the appearance of the
fire:
Appearance
Temp. F.
Appearance
Temp. F.
Red, just visible
Red, dull
997°
1290
1470
1650
1830
Orange, deep
Orange, clear
White heat
1830°
2156
Red, cherry dull
2010
Red, cherry full
White bright
2550
Red, cherry clear
White dazzling
2910
Quantity op Air Required for Combustion of Fuel
Fuel
Air per Pound
Air per Kilogram
Coke
Coal (anthracite) .
Coal (bituminous).
Charcoal
Lignite
Peat, dry
Wood, dry
Petroleum
Producer gas
Cubic Feet
162.06
144.60
143.40
133.90
112.43
•92.36
73.36
172.86
11.56
Cubic Meter
10.09
9.01
8.93
8.53
7.02
5.75
4.57
10.76
.72
See also section on Draft.
OIL
Crude petroleum as it comes from the well varies in physical
and chemical properties in different districts and countries and at
different depths in the same district. It is nearly always lighter
than water. The diagram below shows how by refinement the
various oils are obtained.
Crude Petroleum
Products
of Disl
tillation
Residua
Benzine Lamp Oils
(Commercial)
Spirit
Heavy Petroleum Oils
(Olefiant Gas Oils)
Gasoline
(Motor Oils)
Lubricating Oils Paraffin
Asphaltum
spl
Pi
itch
Digiti
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354
MACHINERY
Gravity
deg. Be\
Flash Point
deg. F.
Burning Point
deg. F.
Crude oil
Kerosene
Distillate (gas oil)
Fuel oil
Residuum
12 to 45
40 to 50
28 to 38
22 to 28
10 to 20
110 to 200
90 to 125
100 to 250
100 to 300
125 to 500
120 to 220
105 to 150
110 to 325
125 to 375
200 to 600
Fuel Oil
(60° F.)
Specific
Beaume
Lb. per
Am. Gal.
Lb. per
Cu. Ft.
Gal. Amer.
Gal. Eng.
Bbls.
Gravity
Grav.
Eng. Gal.
per Ton
per Ton
per Ton
per Ton
1.0000
10.
8.331
10.
35.94
268.875
224.
6.40
.9956
10.5
8.302
9.995
36.09
269.81
224.75
6.42
.9930
11.
8.273
9.930
36.19
270.76
225.55
6.44
.9895
11.5
8.244
9.895
36.32
271.71
226.33
6.46
.9860
12.
8.214
9.860
36.45
272.57
227.13
6.49
.9825
12.5
8.185
9.825
36.57
273.66
227.96
6.51
.9790
13.
8.156
9.790
36.71
274.62
228.80
6.54
.9755
13.5
8.127
9.705
36.84
275.62
229.62
6.56
.9720
14.
8.098
9.720
36.97
276.67
230.49
6.58
.9685
14.5
8.069
9.685
37.10
277.47
231.16
6.60
.9655
15.
8.044
9.650
37.22
278.46
231.98
6.63
.9625
15.5
8.019
• 9.625
37.34
279.33
232.71
6.65
.9595
16.
7.994
9.595
37.46
280.19
233.42
6.66
.9560
16.5
7.964
9.560
37.59
281.26
234.31
6.69
.9530
17.
7.929
9.530
37.71
282.22
235.11
6.74
.9495
17.5
7.910
9.495
37.85
283.08
235.90
6.75
.9465
18.
7.885
9.465
37.97
284.08
236.66
6.76
.9430
18.5
7.856
9.430
38.11
285.13
237.52
6.76
.9400
19.
7.831
9.400
38.23
286.04
238.30
6.81
.9370
19.5
7.806
9.370
38.35
286.95
.239.06
6.83
.9340
20.
7.781
9.340
38.47
287.88
239.82
6.85
.9310
20.5
7.756
9.310
38.60
288.88
240.60
6.87
.9280
21.
7.730
9.280
38.73
289.74
241.34
6.89
.9250
21.5
7.706
9.250
38.85
290.68
242.16
6.89
.9220
22.
7.680
, 9.220
38.98
291.62
242.95
6.94
.9195
22.5
7.660
9.195
39.09
292.42
243.61
6.96
.9165
23.
7.635
9.165
39.21
293.25
244.40
6.98
.9135
23.5
7.615
9.135
39.34
294.15
245.21
7.00
.9105
24.
7.585
9.105
39.47
295.31
246.01
7.03
.9045
. 25.
7.536
9.040
39.73
297.24
247.64
7.07
.8990
26.
7.490
8.990
39.97
299.06
249.15
7.08
.8930
27.
7.440
8.930
40.24
301.07
250.84
7.12
.8870
28.
7.390
8.870
40.51
303.11
252.53
7.21
.8815
29.
7.344
8.815
40.77
305.01
254.00
7.26
.8755
30.
7.294
8.755
41.04
307.10
255.85
7.31
.8700
31.
7.248
8.700
41.31
309.19
257.47
7.36
.8650
32.
7.206
8.650
41.54
310.85
258.94
7.40
.8595
33.
7.160
8.595
41.81
312.84
260.61
7.44
.8545
34.
7.119
8.545
42.05
314.65
262.14
7.40
.8490
35.
7.070
8.490
42.32
316.83
263.83
7.5t
.8440
36.
7.031
8.440
42.58
318.58
265.40
7.58
.8395
37.
6.994
8.395
42.81
320.27
266.82
7.62
.8345
38.
6.952
8.345
43.06
322.67
268.42
7.70
.8295
39.
6.911
8.295
43.32
324.12
270.04
7.71
.8250
40.
6.873
8.250
43.56
325.90
271.51
7.78
y Google
OIL BARRELS 355
General Notes and Terms
To find the weight of a gallon of oil multiply the weight of a
gallon of water at 60° F. (8.328 lb.) by the specific gravity of the oil.
Oil barrels are usually 21 ins. in diameter at the top and bottom,
24 at the middle, 35 ins. high, and contain approximately 51 gallons.
Weight of a barrel of oil = 51 gallons X weight of a gallon of oil
which at 30° Beaume* is 7.29 lb. (see table) = 373 lb. plus the
weight df the barrel or 70 lb. making a total of 443 lb. See page 20.
A quick way to find the capacity of a barrel in Imperial gallom;
use the formula .0014162 X length in inches X (diameter at middle
in inches)2. To convert Imperial gallons into U. S. gallons multiply
by 1.2.
Heavy oils as fuel oils expand, when heated, about 1% for every
25° of temperature, corrections being made to 60° F. If tem-
perature' is above 60°, subtract, and if below, add.
The density of an oil is specified in degrees Beaume* at a tem-
perature of 60° F. For indicating the density an instrument called
a hydrometer (having an arbitrary scale the readings of which are
in degrees) is allowed to float freely in the oil. The Beaume* gravity
value is then read at the point where the surface of the oil inter-
sects the scale.
Specific gravity is the ratio of the weight of a solid or liquid to
an equal volume of water at f>0° F. To calculate the specific
gravity of an oil at any temperature, having given its specific
gravity at 60° F., take the number of degrees above or below 60°
and multiply them by a constant which for heavy oils of 20° Beaume*
and below is .00034, for those of 30° Beaume* .0004, of 30° to 40°
Beaume* .00045, and for refined oil .00050. The product is to be
added to or subtracted from the original specific gravity according
as the temperature is below or above 60° F.
For reducing Beaume* readings at 60° F. to specific gravity use the
formula:
140
Specific gravity
130 + degrees Beaum6
Example. An oil at a temperature of 60° F., has a reading of 22 on the Beauine*
scale. Find its specific gravity.
140
Specific gravity - ^ + g2 - .922
Digiti
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356 MACHINERY
Specific Gravities and Weights op Various Oils
Oil
Specific
Gravity
Weight
Pounds per
Cubic Foot
Vegetable oils
Mineral lubricating oils
Petroleum
Petroleum, refined ....
Benzine
Gasoline
.91— .94
.90— .93
.87
.79— .82
.73— .75
.66— .69
58
57 s
54
.50
46
42
Flash point of an oil is the lowest temperature at which the
vapors arising therefrom ignite, without setting fire to the oil itself,
when a small test flame is quickly brought near its surface and
quickly removed.
Fire point is the lowest temperature at which an oil ignites from
its own vapors when a small flame is quickly brought near its sur-
face and quickly removed. The fire point is about 50° above
the flash point. *
The viscosity of an oil is told by the number of seconds required
for a certain quantity to flow through a standard aperture at con-
stant temperatures, generally at 70°, 100° and 212° F. Gasoline
is an example of a non-viscous oil.
Color does not indicate the quality of an oil, neither does it
show if it is suitable for any particular service.
Chill or cold test is the lowest temperature at which an oil will
pour. It gives no idea of the lubricating properties of an oil.
Oil for Boilers. — Oil between 15° and 30° Beaume* is, as a rule,
suitable for boilers. It should not be too heavy to be easily vapor-
ized by a jet of steam or to cause trouble in cold weather, and
not so light and volatile as to be flashy.
With internally mixed burners where the oil and steam come
together inside the burner it is necessary to maintain sufficient
pressure of oil to overcome the back pressure of the steam and at
the same time supply the proper amount of oil. This requires
a pressure from 30 to 50 lb. With externally mixed burners, it is
necessary to have only a pressure to insure the free passage of oil
through the pipes, which is 4 to 5 lb. It is desirable in both types
to heat the oil to a temperature of around 150° F.
Heat Values of Oil. — 14 to 15 lb. of water are evaporated into
steam from and at 212° F., per pound of oil. Assuming 15 lb., then
nvJ^v^
FUEL OILS 367
one horse power will be developed with 2.3 lb. of oil. The heat
value of mineral oils and their products may be closely determined
from their Beaume' gravity by the formula: B. t. u. per lb. ■=
18650 + 40 (Beaume* gravity - 10).
Per cent, of Total Steam Generated Used for
Atomising Oil in the Burners
Pounds of Steam for
Atomising Oil per Pound
1
.15
1.5
.225
2
.30
2.5
.375
3
.45
3.5
.525
4
.60
4.5
.675
5.
.75
Assume the average evaporation from and at 212° F. per pound
of coal to be 7 lb., and for oil 15, then the ratio of evaporation
is 7 to 15 and the pounds of oil equivalent to 2,000 lb. of coal will
be 7 : 15 - x : 2000 or x - 933 lb., which divided by 373 (as-
sume the oil in a barrel weighs 373 lb.) equals 2.5 barrels of oil as
being equivalent to one ton (2,000 lb.) of coal, or 2.8 barrels to
one ton of 2,240 lb.
From one pound of crude oil there can be obtained from 1.6 to
1.7 times as many British thermal units as from a pound of coal.
In other words, one pound of oil is equivalent to 1.6 lb. of coal.
If 34 to 35 cu. ft. of oil weigh a ton (2,240 lb.), assuming that
42 cu. ft. of coal weighs the same amount, there is thus saved in
stowage space with oil 15 to 20%. One ton of petroleum contains
approximately 275 Imperial gallons or 360 U. S. gallons.
Air required for the complete combustion of fuel oil is about
200 cu. ft. per pound.
Fuel Oils for Internal Combustion Engines. — Crude oil is only
for Diesel engines, as electrically ignited engines will not run on it,
but will on distillate, gasoline, and kerosene. See Internal-Com-
bustion Engines.
The Beaume* gravity is not always a true indication of the fuel
value of the evaporization of an oil. The origin of the crude oil
from which the fuel oil is obtained may also give rise to a vari-
ation in its gravity without affecting its ease in evaporation.
Digitized by VjiOOQLC
358 MACHINERY
A practical test which shows at once the volatility of liquid fuel,
is the determination of the limits of its boiling point, which consists
in observing:
1. The initial boiling point.
2. Per cent, of volume distilling over at several intermediate
temperatures.
3. The final boiling point.
Gasoline (in England called petrol and in France essence) is
a colorless inflammable fluid, the first and highest distillant of
crude petroleum. The specific gravity ranges from .58 to .90 com-
pared with the unit one assumed for water at 60° F. For every
20° F. the specific gravity varies .01. Measured on the Beaume*
scale higher specific gravities are denoted by lower numbers, and
lower specific gravities by higher numbers without definite gradu-
ations.
Gasoline is not a simple chemical compound like water but a
physical mixture of chemical compounds of carbon and hydrogen,
each compound having different boiling points. In general, the
higher the initial and final boiling points the more difficult will be
the starting of an internal combustion engine on cold mornings,
calling for the heating of the mixing chamber of the carbureter or
the inlet air which passes to it.
Lubricating Oil. — The desirable characteristics are: (1) the oil
should possess cohesion ; (2) it should possess the maximum possible
adhesion; (3) it should be as far as possible unchangeable; and
(4) it should be commercially free from acid and be pure.
Tests have shown conclusively that no one grade however high
its quality is suitable for all types of steam and internal combustion
engines, because of the different surfaces to be lubricated and the
systems employed in feeding the oil. Hence from the engine
builder should be obtained information on the oil that is best suited
for his engine.
In steam engines the amount of lubricating oil differs greatly,
but from 5 to 8 lb. of oil per ton of coal may be taken as a fab-
average, or say from 5 to 8 lb. per 1,000 i. h. p. per hour. In small
high speed engines as in torpedo boats the above amounts are
exceeded.
Special oils are required for the cylinders of internal combustion
engines on account of their high temperatures, ranging from 600°
to 700° F. The oils must not only have good lubricating prop-
erties, but should not leave behind any carbon. A carbon deposit
Digitized by vjOOQ 1C
VARIOUS LUBRICATING OILS
359
and heavy exhaust smoke usually indicates that the oil is too light.
The consumption of a light oil is much greater than a heavy. Under
ordinary conditions the oil used for the bearings and for the cylin-
ders should not exceed \XA gallons per 1,000 i. h. p. in 24 hours.
The viscosity of an oil may be increased by a thickener as oleate
of alumina, but although a thickener brings up the viscosity it does
give the greasiness expected when a particular viscosity was specified, *
At ordinary temperatures, a very small quantity of oleate of alumina
will considerably raise the viscosity of an oil.
If an oil is to lubricate a bearing, it must be fluid enough at the
temperature of use to flow readily into the bearing. Hence it is
customary to chill samples of oil and to determine the temperatures
at which they become too thick to flow readily.
Uses and Characteristics op Various Lubricating Oils
Kind of Oil and Use
Gravity
Beaume
Flash
Test
Degrees F.
Fire
Test
Degrees F.
Viscosity
at 70° F.
(water =1)
High pressure cylinder oils: for cyl-
inders using dry steam from 110 to
2101b
General cylinder oil: for cylinders us-
ing dry steam from 75 to 100 lb.
Also for air compressor cylinders
when the oil is made from steam re-
fined mineral stock and has a vis-
cosity of 200
Wet cylinder oil:* for cylinders using
moist steam, especially in compound
and triple expansion engines
Gas engine cylinder oilf
Heavy engine and machinery oils: for
heavy slides and bearings
Wet service and marine oils$
25-24.5
26-25.5
25.8-25.3
26.5
30.5-29.5
28
600-610
550-585
560-585
320
400
430
645-660
600-630
600-630
350
440-450
475
175-205
180-190
150-185
300
170-175
230
* May contain 2 to 6% of refined acidless tallow oil in the high pressure oils and
6 to 12 in the low pressure.
t Neutral mineral oil compounded with soap. The soap will not decompose
at high heat, and although not a lubricant serves as a vehicle for carrying some oil.
t May contain 30 to 40% of pure strained lard oil.
Notes on Lubricating Oil.*
A mineral oil flashing below 300° F. is unsafe on account of
causing fire.
A mineral oil evaporating more than 5% in 10 hours at 140° F.
is inadmissible as the evaporation creates a viscous residue or
leaves the bearing dry.
* Notes from "Animal and Vegetable Fixed Oils and Waxes. " C. R. A. Wright.
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360
MACHINERY
The most fluid oil that will remain in its place, fulfilling all other
conditions, is the best for all light bearings at high speed.
The best oil is that which has the greatest adhesion to metallic
surfaces and the least cohesion in its own particles, in this respect
fine mineral oils are first, sperm oil second, neatsfoot oil third,
and lard oil fourth.
Consequently the finest mineral oils are best for light bearings
and high velocities.
The best animal oil to give body to fine mineral oils is sperm
oil. Lard and neatsfoot oil may replace sperm oil when greater
tenacity is required.
The best mineral oils should have the following properties:
Where Used
Evaporating
Temperature
Degrees F.
Flashing
Temperature
Degrees F.
Steam cylinders
Heavy machinery
Light bearings and high ve-
locities '.
.880
.871
560
443
424
680
518
505
Mineral oils alone are not suited for the heaviest machinery on
account of want of body and high degree of inflammability.
Olive oil is foremost among vegetable oils as it can be purified
without the use of mineral acids. The other vegetable oils ad-
missible but far inferior, stated in their order of merit, are gingelly,
groundnut, colza and cotton seed oils.
No oil is admissible which has been purified by means of mineral
acids.
Oil Burning Systems. — When fuel oil has a flash point of not
lower than 150° F. the oil bunkers may be on both sides of the
boilers, or at the sides of the expansion trunk, or in tanks forward
of the oil space. For oil having a lower flash point than 150° F.
a different arrangement is required, the oil compartments being
separated from the engine and boiler spaces by a cofferdam. When
high flash oil is carried the fuel pumps for pumping the oil into
the settling tanks and boilers are usually placed in the stokehold.
When low flash, a special pump room is built in the boiler space abaft
the cofferdam. This pump room is a watertight compartment, is
tested by being filled with water to the top, and has no direct
communication with the machinery space. It contains only the
pumps and a ventilating fan (see Oil Carriers).
' Digitized by VjOOQLC
Digitized by VjOOQ LC
362 MACHINERY
The open system of piping to the oil burners, in which oil cir-
culates all the time through the heater and burner pipes and back
to the pump suction, is often preferable for marine installations
to the dead end system in which the oil simply goes to the burners.
The piping must be carefully erected, with no rubber gaskets or
packings.
For the U. S. Naval Service the oil piping is seamless drawn
steel, with flanges expanded on. The joints are scraped and made
up metal to metal. Manila paper gaskets are allowed on suction
pipes. Screwed fittings are used on connections under % in.
For merchant service extra heavy welded iron or steel pipe is
used, with screwed joints and with extra heavy galvanized iron
fittings. Flanges are screwed on the pipes and manila paper or
cardboard is used for gaskets or special oilproof packing. Copper
piping is not used, but brass and composition fittings and valves
may be used.
The suction piping should be large, the practice at Newport
News Shipbuilding Co., Newport News, Va., for the velocity of
Mexican oil through suction pipes is not over 20 ft. per minute,
the oil being heated to reduce the viscosity to about 30° Engler.
For discharge pipe lines 100 ft. per minute is allowable in small
pipes, the viscosity being reduced to 15° Engler or lower. It is
dangerous to use a fuel oil which, to reduce its viscosity 'sufficiently
for mechanical atomization, has to be heated beyond its flash point.
Below are brief descriptions of the Koerting, White, and Kermode
oil burning systems. In the Koerting, the oil is atomized by
mechanical action, it being forced by pumps through superheaters
to the burners. On the way from the superheaters to the burners,
the oil which is under high pressure and of the required temper-
ature is strained. After straining it goes to burners which are
fastened to adjustable air registers provided with air admission
slides to regulate the air supply so as to secure a proper mixture
of air and oil.
The oil leaves the burners perfectly atomized and the air for
combustion is carried to the atomized oil by the air registers that
are so constructed as to cause the air to form an intimate mixture
with the oil, thereby securing complete combustion. The Koerting
system is placed on the market by Schutte and Koerting, Phila-
delphia, Penn.
In the White system (see Fig. 52) the burner is designed to break up
or atomize the oil as fine as possible. This is accomplished by driving
Digitized by vjOOQ 1C
BOILERS 363
the oil along a number of flutes or passages on a cone, and with-
out retarding its velocity impinging it on a fine-angled cone, de-
livering it from the orifice in a spray at a pressure of 60 lb. which
can be reduced to 10, the spray being still fine enough to flame.
The flame burns at about one inch from the burner due to the
perfect mixture with the air, and complete combustion is obtained.
The White system is installed by the White Fuel Oil Engineering
Co., New York.
In the Kermode system there are three. different types: (1) the
pressure jet where the oil is atomized by pressure — with this type
neither steam nor air is required to disintegrate the oil, it being
effected by pressure that is brought to bear upon the oil fuel itself
by means of a force pump; (2) the oil is atomized by air pressure;
and (3) the oil is atomized by steam pressure. Before the oil
reaches the burners it is heated and filtered. The use of com-
pressed air in place of steam is more economical and generally hot
air is to be preferred when the best results are desired. The Ker-
mode system was brought out by Kermode's Ltd., Liverpool, Eng.
BOILERS
There are two types of boilers, one where the fire goes through
the tubes (fire tube boiler) and the other where the water does
(water tube boiler). Of the former the most common is the Scotch
boiler shown in Fig. 53. Their usual proportions are as follows:
Sectional area of tubes i to } the grate surface.
Volume of combustion chamber 3 to 4 cu. ft. per square foot of
grate surface.
Grate surface 10 to 15 sq. ft. per i. h. p.
Heating surface 2 to 15 sq. ft. per i. h. p.
Ratio of heating surface to grate varies from 16 to 30.
Steam volume .3 to .4 cu. ft. per i. h. p.
Coal burned 15 to 35 lb. per square foot of grate surface per hour,
or % to 1 lb. per square foot of heating surface per hour.
Water evaporated 6 to 10 lb. per pound of coal, or 4 to 10 lb.
per square foot of heating surface per hour.
Sectional area of funnel \ to J grate surface.
Scotch boilers may be built in 2,000 h. p. units or even larger.
For weights, see page 000.
A good boiler working under favorable conditions will absorb 85%
of the heat generated by the fuel, but 75% is the usual average.
Data from Prac. Marine Engineering.
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364
MACHINERY
Scotch Boilers
Diameter, mean
Length over end plates
Working pressure, lb
Rules on which designed
Number of furnaces
Diameter of furnaces, external
Thickness of furnaces
Number of combustion chambers
Number of tubes
Diameter of tubes
Length of tubes
Surface of tubes, sq. f t
Total heating surface, sq. ft
Grate area, sq. ft
Thickness of shell, ins
Diameter of shell rivets
Pitch of shell rivets
Tensile test of shell plate
Thickness of top end plates
Thickness of front tube plates
Thickness of back plates
Thickness of combustion chamber
Weight as finished in tons
Weight per 100 sq. ft. total heating surface
in tons
From Marine Eng'g Estimates. C. R. Bruce.
The combustion chamber of a Scotch boiler should have a water
space of at least 5 ins. between it and the end of the boiler. The
space should be wider at the top than at the bottom, the chamber
having a slope of about H in- per foot of depth. Measured hori-
zontally they should be as deep as possible, 28 and 36 ins. seem to
be the smallest limits for single- and double-ended boilers respec-
tively. The depth is about 12 ins. greater than one-half the furnace
diameter for single-end boilers, and for double-end it is about
24 ins. greater.
In boilers with two furnaces the ratio of boiler diameter- to
furnace diameter is approximately as 10 to 3. Custom is equally
divided as to leading the two furnaces into two combustion cham-
bers or into one. In estimating the heating surface of a corrugated
furnace assume it as a plain cylindrical furnace whose diameter
is the mean diameter of the corrugations. For boilers with three
furnaces, the ratio of boiler diameter to furnace is as 4 to 1. Usu-
ally three combustion chambers are fitted. For boilers with four
furnaces the ratio of boiler diameter to furnace is as 5 to 1. Com-
bustion chambers are generally arranged so that the two central
furnaces are led into one, and the two wing into separate chambers
so there would be one large and two small combustion chambers.
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366
MACHINERY
Particulars of Single Ended Scotch Boilers
Natural Draft
Mean
Internal
Mean
Length
Mean
Internal
Diameter
of
Furnaces
Width
of Com-
bustion
Chamber
Tubes
Heating
Surface
Length
of Fire
Bars
Grate
Area
Diameter
Number
Dia.
Length
13' 6»
14' 0*
14' 6*
15' 0*
15' 6*
16' 0*
16' 6*
10' 3*
10' 6*
10' 6*
10' 9*
11' 0*
ll'O'
11'3'
3'2»
3'4»
3' 6*
3' 8*
3'9M'
3' 11*
4'1*
2'5M*
2' 6*
2' 6*
2' 7H'
2' 9*
2' 9*
2' 10*
198
204
238
254
268
280
284
3H'
3H*
3 V
3H'
3M*
7'0*
V 2'
V 2'
V 3*
V 4*
7' 4*
V 6*
1608
1694
1949
2100
2234
2331
2425
5'9»
6'0»
6'0»
6'0»
6'0»
6'0»
6'0»
54.6
60.0
63.0
66.0
68.2
70.5
73.5
Forced Draft
13' 6*
ll'O'
3' 2'
2' 5H'
322
2H'
V 9.'
1986
5'0*
47.4
14' 0*
ll'O'
3' 4'
2' 6*
345
2H'
7' 8*
2098
5'0'
50.0
14' 6*
11'3'
3' 6*
2' 7*
386
2)4'
7' 10'
2390
5' 3*
52.5
15' 0*
11' 6'
3' 8*
2'IVS
407
2)4'
8'0*
2560
5' 3'
55.0
15' 6*
11'9'
3'9H"
3' 11*
2' 9'
425
2H'
8' 3*
2749
5' 3*
56.87
16' 0*
12' 0'
2' 9*
482
2H'
8' 4'
3111
5' 6'
58.75
16' 6*
12' 3'
4'1'
2'10K
510
2H'
8' 6*
3352
5' 6'
61.25
Note. The boilers in the above list are fitted with three of Mormon's with-
drawable furnaces, each leading into a separate fire box. The center line of the
top row of tubes is about one third of tne boiler diameter from the top, which
represents good practice for pressures from 140 to 190 lbs. For higher pressures,
the steam' space may be reduced, and the heating surface increased. (Above
table from Marine Eng'g Estimates. C. R. Bruce.)
The locomotive type is shown in Fig. 54. Here the furnace is
of a rectangular cross section, and is surrounded by the shell at
the front, leaving on the sides a narrow space known as the water
leg. When so constructed that there is a space at the bottom
below the firebox, the boiler is known as the wet bottom type,
and where there is no space, as in Fig. 54, the dry bottom.
Fig. 55 is of a flue and return tube or leg boiler. The hot gases
pass from the furnace through large tubes or flues to a combustion
chamber at the farther end, returning through small tubes and
thence through the uptake to the funnel. The furnace has a
rectangular cross section, and the front end of the boiler is modified
on the sides and bottom to correspond to this form. Water legs
are formed on the sides of the furnaces and from them the boiler
gets its name. When built with the front end having flat sides and
a rounded top it is known as a wagon top boiler.
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368
MACHINERY
Locomotive and leg boilers are installed in shallow draft vessels,
such as excursion steamers, where a Scotch boiler on account of
its large diameter would seriously interfere with the arrangement
of the decks.
Figure 55.-rLeg Boiler.
From Prac. Marine Engineering.
Water-Tube Boilers. — Here the grate lies below the tubes and
frequently between the lower drums, while the tubes and drums
are surrounded by a casing to prevent as far as possible the loss
of heat by radiation.
The feed water enters the upper drum, then flows down certain
of the tubes to the lower drums from which the water enters the
upflow or steam forming tubes that are surrounded by the hot
gases from the grates. During the passage of the water upward
it is partly converted into steam, and the mixture of steam and
water issues from the upper ends of the tubes into the drum. Here
the steam is separated and enters the piping to the engine or tur-
nvJ^v^
THE YARROW BOILER 369
bine, while the water mixes with that already in the drum and begins
on another round.
The Yarrow has straight tubes, while the Thomycroft, Normand
and White-Forster have curved tubes. In the latter there is a
center and side drums (see Fig. 56), the tubes being curved to a
standard, radius and are interchangeable. Thus spare tubes can
be carried in straight lengths and may be bent and cut as desired.
The Yarrow, Thomycroft, Normand, and White-Forster boilers
belong to the small tube type and have been installed in a large
number of torpedo boats, destroyers, and other high speed steam
Of the large-tube water-tube boilers the Babcock and Wilcox
(see Fig. 57) is well known. The tubes forming the heating surface
are divided into vertical sections and to insure a continuous cir-
culation in one direction are placed at an inclination of 15° with
the horizontal. Extending across the front of the boiler and con-
nected to the upper ends of the headers by 4-inch tubes is a hori-
zontal steam and water drum. As the upper ends of the rear headers
are also connected to this drum by horizontal 4-inch tubes each
Figure 56.— White-Forster Water-Tube Boiler.
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370
MACHINERY
section is provided with an entirely independent inlet and outlet
for water and steam. Placed across the bottom of the front header
and connected thereto by similar 4-inch tubes is a forged steel box
with a 6-inch square section. The box situated at the lowest
corner of the bank of tubes forms a blow-off connection or mud
drum through which the boiler may be completely drained. The
distance traveled by the products of combustion in contact with
the heating surface is about 16 ft.
The weight of Babcock and Wilcox boilers including water, as
built for naval vessels and mail steamers, for 250 lb. pressure is
about 25 lb. per square foot of heating surface.
Weight, and Space Occupied by Various Makes of Water-
Tube Boilers
Weight
of Boiler
and
Floor
Outside
Heating
Water
Make
Name of Steamer
Length
Width
Height
Space,
Sq.Ft.
Dia.of
Tubes
Surface.
Sq.Ft.
per
Sq.Ft.
Heating
Surface
in Lb.
Babcock and
U. S. Battleship
Wilcox
Utah
9' ir
18' 4i"
13' 111*
167.68
2*4 4*
5,359
•23.79
Babcock and
U. S. Battleship
Wilcox
New Hampshire
1C 1*
14' 10*'
13' 21*
149.98
2* A 4*
3,926
•25.80
Normand
U. S. Torpedo
Boat Destroyer
Thornycroft. .
Trippe
U. S. Torpedo
Boat Destroyer
12' 6*
15' ir
14' 2'
188.60
l'&H'
4,780
tl2.40
Terry
10' 9*"
15' 2f
12' H'
164.30
U'AH'
4,500
tl2.20
White-Forster
Torpedo Boat
Destroyer
Mary ant
9' 01'
14' 8i*
12' 8*
133.30
1*4 If
4,500
tl2.10
Yarrow
Torpedo Boat
Destroyer
Sterrett
12' 9'
14' 2|* 12' 10*
181.00
l*Ali*
4,500
tl2.50
• Includes grates— coal burning. From Steam, Babcock A Wilcox Co.
t Oil burning— no grates.
Comparison of Fire-Tube and Water-Tube Boilers. — Fire-tube
boilers take longer to get up steam. For example, Scotch boilers
require between five and six hours to raise steam after the fires
are started, whereas water-tube require from 30 to 60 minutes.
Then again fire-tube boilers are heavier than water-tube (see
Weights). f
Digitized by LiOOQ LC
BOILER HORSE POWER 371
Water-tube boilers can stand forcing, are suitable for high steam
pressures, and can raise steam quickly. Their disadvantages are:
a more rigid restriction of the feed to fresh water; the necessity
of a greater regularity of feed; greater difficulty in dealing with
leaky tubes; general sensitiveness to variation in the conditions
of use; and perhaps they are not so durable or so efficient as Scotch
boilers when on long voyages. Their maximum size is about
1,000 h. p., while Scotch have been built to about 2,000. The
above applies particularly to small water-tube boilers. Large-tube,
as the Babcock and Wilcox, have many of the advantages of Scotch
boilers, with the additional advantage of being able to raise steam
much quicker, which is of the greatest importance in warships.
Boiler Horse Power. — The evaporation of 34.5 lb. of water per
hour from a feed water temperature of 212° F. into steam at the
same temperature is a standard commercial boiler horse power
and is considered as equivalent to the evaporation of 30 lb. of
waiter per hour from a feed water temperature of 100° F. into steam
at 70 lb. pressure.
For finding the approximate boiler horse power in water-tube
boilers divide the total heating surface in square feet by 10. In
ordinary Scotch or leg boilers, multiply the area of the grate sur-
face in square feet by 3, or divide the number of tons of coal burned
per hour by 3J^. The results from the above formulae express the
evaporative capacity of a boiler in horse power based on the evapo-
ration of 30 lb. of water per horse power per hour.
To Find the Boiler Horse Power Required for an Engine.
Let i. h. p. = indicated horse power of the engine
B. H. P. = boiler horse power required
8 = water rate or steam consumption in pounds
per L h. p. per hour
e = ratio of steam required for the auxiliary ap-
paratus, such as feed pumps, etc., and
may be taken as 1.08 for condensing en-
gines and 1.02 for non-condensing
ThenB.g.P.-ffep34X58Xc
Example. Find the boiler horse power required to supply steam to a 600 h. p.
compound condensing engine.
From the table of steam consumption (see section on engines) 15 lb. of steam
are consumed per i. h. p.
Using the above formula
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372
MACHINERY
B. H. P. - *'■*-» * ' Xc « 600 X15 X1.08 _ ^
34.5
34.5
The following is another example:
Example. Find the size of boiler required for a fore and aft compound engine
with cylinders 10 and 20 ins. diameter by 14 ins. stroke, cutting off at 10H-inch
stroke, working pressure of boiler, 160 to 165 lb., piston speed, 600 ft. per minute.
First determine the probable indicated horse power of the engine. The general
formula for mean effective pressure (MEP) (theoretical) is:
Figure 57.— Babcock and Wilcox Water-Tube Boiler.
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FACTOR OF EVAPORATION 373
MEP - pi i- (1 + log., n) — p.
n
where pi *- boiler pressure
n = number of expansions
pi * back pressure
if pi ■ 160 lb. per sq. in. (boiler pressure)
10 X 10 X x X 14
n 5X5XtX 10.5 " 633
and pi -» 4 lb. per square inch (assumed}
then MEP - 160 X ~g (1 + log. J5.33) — 4
-160 x^gd+l.OTM)— 4
« 80.2 — 4 «■ 76.2 lb. per square inch.
The ratio of theoretical mean effective pressure to probable mean effective
pressure is about . 55 for the above type of engine, so that
. . _ MEP X piston speed X area lower pressure cylinder
P* * 33,000
41.9 X600 X314.
33,000
A steam consumption including auxiliaries of 25 lb. per h. p. hour is reasonable
for this type of engine used I — — — J and gives 239 X 25 - 6,000 lb. per hour
approximately, as the evaporation of the boiler. The equivalent evaporation from
and at 212° is
Heat contents at 165 lb. X 6,000 1,196 X 6,000
Heat contents at 212° 1'150
-» 6,200 lb. approximately
Boiler horse power — »' e — 180.
o4.5
For Scotch boilers about 7 lb. of steam per square foot of total
heating surface is as much as should be counted on, which would
give -= — = 857 sq. ft., and allowing 35 sq. ft. of heating surface
857
per 1 sq. ft. grate, the grate area is -^r- = 24.5 sq. ft. Therefore,
a Scotch boiler for the given conditions should have about 860 sq.
ft. of heating surface and 24.5 sq. ft. of grate area. If forced draft
is used it is probable that the horse power per square foot of grate
area would be about 15, which would give a much smaller boiler.
In designing large boiler plants it is generally considered suffi-
cient to provide boiler horse power equal to one-half the indicated
horse power of the engine.
Factor of Evaporation for any given feed water temperature
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374 MACHINERY
and boiler pressure is calculated by dividing the total heat above
32° F. in one pound of steam at the given pressure minus the total
heat in one pound of the feed water above 32, by the latent heat
of steam at 212° which is 970.4 B. t. u. ,
Example. A boiler evaporates 5,000 lb. of water at 77° F. into steam at 91 . 3
lb. gauge pressure every hour. What is the boiler horse power?
From the steam table, steam at 91 .3 lb. gauge pressure contains 1,187.2 B. t. u.
per lb. above 32°.
Water at 77° contains 77-32 = 45 B. t. u. per lb. above 32°.
Then the factor of evaporation =» — — Q ' = 1 . 177
5,000 lb. of feed water per hour multiplied by 1 . 177 = 5,885 lb. of water which
would have been evaporated into steam with the same heat used to evaporate
5,000 lb. from 77° into steam at 91.3 lb. if the feed water temperature had been
212° and the boiler pressure 0 lb. The equivalent evaporation from and at 212° is
5,885 lb., and divided by 34 . 5 lb. gives 170 . 6 as the b. h. p. (From Oil Fuel).
Boiler Efficiency is the ratio of the heat actually transmitted
to the water in the boiler to the total heat developed by the com-
bustion of the fuel. This is determined by the quantity of feed
water fed to the boiler, amount of coal burned, steam pressure
in boiler, and temperature of feed water.
Example. In a boiler, 864 lb. of coal were burned per hour, the feed water
entering the boiler 8,350 lb. per hour, temperature of feed water 100° F., and the
steam was blown into the atmosphere at 275 lb. per square inch. Find the efficiency
of the boiler.
The calorific value of the coal used was 15,120 B. t. u.
Total heat per pound of dry saturated steam at 275 lb.; calculated from feed
water at 32° is 1,208.3 B. t. u.
The heat added per pound of feed water leaving the boiler as dry steam at 275
lb. - 1,208.3 - (100° - 32°) - 1,140.3 B. t. u.
Hence the heat carried away by 8,350 lb. of steam is 1,140.3 X 8,350 = 9,521,505.
The heat from combustion if 864 lb. of coal is burned is 864 X 15,120 = 13,063,-
680 B. t. u.
Then the boiler efficiency is ' ' go, = .73 nearly.
lo,UOo,OoU
The following is another example. Find the efficiency of a boiler when the
evaporation from and at 212° is 7 lb. of water per 1 lb. of coal containing 12,000
B. t. u. per pound.
7 X 970.4 Gatent heat of steam) - 6,793 B. t. u. imparted to the water per
one pound of coal.
Then ^qqq = 56 or 56% efficiency.
Efficiency of small tube water tube boilers — 58%
Efficiency of large tube water tube boilers 63 to 70%
Efficiency of Scotch boilers 68 to 80%
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BOILER WEIGHTS
375
Approximate distribution of heat in a Scotch boiler burning
20 lb. of coal per square foot of grate surface, the heating surface
being 30 times the grate, is as follows:
Absorbed by feed water 68%
Wasted in funnel gases 24
Wasted in unburned carbon in ashes 2
Wasted by radiation, etc 6
Total 100%
The heat absorbed by the feed water, viz., 68%, represents the
efficiency of the boiler.
Boiler Weights, Scotch and water-tube, see Machinery Weights.
Gallons op Water Evaporated per Minute in Boilers
Based on 30 lb. or 34J^ lb. per horse power. To find the gallons
per minute multiply boiler horse power by .069 when evaporation
is 34.5 lb. per hour and .06 when evaporation is 30 lb. per hour.
Gallons
Gallons
Gallons
Gallons
H. p. of
per Minute
per Minute
H. p. of
per Minute
per Minute
Boiler
at 30 lb.
at 34.5 lb.
BoUf.r
at 30 lb.
at 34.5 lb.
per H. p.
per H. p.
per H. p.
per H. p.
25
1.5
1.725
300
18.0
20.7
50
3.0
3.45
325
19.5
22.4
55
3.3
3.79
350
21.0
24.15
60
3.6
4.14
375
22.5
25.87
65
3.9
4.48
400
24.0
27.6
70
4.2
4.83
450
27.0
31.0
75
4.5
5.17
500
30.0
34.5
80
4.8
5.52
550
33.0
37.7
85
5.1
5.86
600
36.0
41.4
90
5.4
6.21
650
39.0
44.8
95
5.7
6.55
700
42.0
48.3
100
6.0
6.9
750
45.0
51.75
110
6.6
7.59
800
48.0
55.2
120
7.2
8.28
850
51.0
58.6
125
7.5
8.625
900
54.0
62.1
130
7.8
8.97
950
57.0
65.5
140
8.4
9.66
1000
60.0
69.0
150
9.0
10.35
1100
66.0
75.9
160
9.6
11.04
1200
72.0
82.8
170
10.2
11.75
1300
78.0
89.7
175
10.5
12.075
1400
84.0
96.6
180
10.8
12.42
1500
90.0
103.5
190
11.4
13.11
1600
96.0
110.4
200
12.0
13.8
1700
102.0
117.3
225
13.5
15.52
1800
108.0
124.2
250
15.0
17.25
1900
114.0
138TC81
275
16.5
18.97
2000
120.WtiZE
376 MACHINERY
Boiler Fittings and Accessories
Fitting
Location on Boiler
Main stop valve
On top
On top
On top
On top
End or side
Auxiliary stop valve
Steam to whistle
Safety valve
Gauge glass connections
8^111*1 f-Ortk
End " "
Auxiliary feed check valve
End " "
Main feed check valve ....
End " "
Test cocks
End " "
Salinometer cock i
End " "
Blow down cock
Bottom
Drain cock
Bottom
Safety Valve. — To provide for the escape of the steam should the
pressure in the boiler rise above the safe working limit for which
the valve is set. The valve must be direct connected to the boiler
without any intermediate valves or pipe bends.
Where A = area of safety valve in square inches, per square foot
of grate surface.
W = pounds of water evaporated per square foot of grate
surface per hour.
P =* absolute pressure per square inch = working gauge +15.
The size for U. S. Steamboat-Inspection Service is determined
by the formula A = .2074 X ?•
Whenever the area, as found by the above formula is greater
than that corresponding to 4J£ ins. diameter, two or more safety
valves, the combined area of which shall be equal at least to the
area required, shall be used. This calls for a single Y fitting to
the boiler with two valves, or to a twin valve. See Fig. 58.
There are two types of safety valves: (1) where the steam acts
on the area of the valve when closed; and (2) where the valve
disk has an additional area not exposed to the steam when the valve
is closed, but acted upon by the pressure of the steam when the
valve opens. The former usually has a lever and weight, while
the latter is spring operated and is known as a pop safety valve.
Pop safety valves are extensively used in the marine field; an
example is the Ashton (Ashton Valve Co., Boston, Mass.), as shown
in Fig. 58. Ashton valves have a patent blow-back head forming
JVJCJVIV^
STOP VALVE
377
Figure 58.— Pop Safety Valve (Aahton Valve Co., Boston, Mass.)
a chamber inclosing the spring and protecting it from the steam.
The spring chamber is vented at the top, thus the discharge from
a number of valves may be piped together, and yet a valve will not
be loaded with back pressure. If desired the pipe from the valve
or valves may run down the inside of the hull to below the water
line, thus giving a noiseless discharge.
Stop Valve. — This valve is in the pipe leading from the boiler
to the main steam .line to the engines, and thus controls the supply
of steam from the boiler. In warships and often in merchant ships
the stop-valve is a non-return valve, and is self-closing, for should
the boiler be ruptured, the valve by closing would stop a sudden
rush of steam from the other boilers.
Feed Water Connections for a Scotch Boiler. — Feed water heaters
are installed in all first class vessels, and the feed water enters
the boiler at about 200° F. The customary practice is to discharge
ile
378 MACHINERY
the water above the tubes just below the water level in the boiler,
through two or more branches led over the tubes with the ends closed
and the sides perforated with small holes, the combined area to
be \Yt times the area of the feed pipe. In no case should the
discharge terminate above the water level in the steam space, for
the reason that it would produce excessive priming and also air
hammer in the feed lines. Quantities of air pass into the boiler
with the water at all times, which produces a certain amount of
hammer in the line, and to overcome this an air chamber of ample
capacity should be placed on the discharge side of the feed pump
or in some convenient place in the feed line.
The U. S. Steamboat-Inspection Rules require all boilers to have
two feed connections, viz., main and auxiliary. Sometimes the
auxiliary is connected only with the injectors and is seldom used
except for supplying the boilers sufficiently to keep the auxiliary
machinery running when the main units are shut down. The
auxiliary discharge should be placed above the furnaces, preferably
about halfway to the top row of tubes.
Feed Check Valve. — The water from the feed pump goes to the
boiler through the feed pipe, and at the boiler passes through the feed
check valve, which is a screw-down, non-return valve, and enters
the internal feed pipe (see above). A stop valve is always placed
between the check valve and the boiler, so if necessary for exam-
ination or repair the check valve may be shut off from communi-
cation with the boiler. In water tube boilers the feed water enters
the upper drum.
Surface and Bottom Blows. — Cocks or valves and connecting
pipes leading overboard are fitted for blowing the grease scum and
mud sediment out of the boiler. The cross-sectional area of the
bottom blow may be so proportioned ajs to give one square inch
for every 5 tons of water contained in the boiler, with a larger
area for small boilers. The area for the surface blow is the same as
the bottom blow.
Steam Gauges. — The steam pressure within the boiler, or rather
the excess of pressure within over the atmospheric pressure, is
shown by a gauge, which is generally of the type using a Bourdon
tube. Steam does not enter the gauge nor does it come in contact
with any of the working parts. The tube from the boiler is bent
in a loop or U, which serves as a trap for the water condensed
beyond this point. Thus the Bourdon tube and part of the con-
necting pipe are kept filled with water, which in turn is acted on
Digitized by VjOOQ IC
FUSIBLE PLUGS 379
by the steam, and the pressure is indicated without the actual
presence of steam within the gauge.
Water Gauge and Cocks. — The level of the water is shown by
a vertical glass tube, the upper end being connected to the steam
space and the lower to the water. The glass should be adjusted
so that when the water is at the bottom, the water in the boiler is
still 3 or 4 ins. above the level of the highest heating surface. Besides
the gauge glass, small cocks are provided which, on opening, indi-
cate the water level in the boiler.
Boiler Circulators. — To improve the circulation of the water —
particularly in Scotch boilers — circulators are installed. Of the
types on the market the Ross-Schofield and the Eckliff are worth
noting. The former consists of steel plates fastened to the out-
side of the combustion chamber and extending to the back plate
of the boiler. By means of these plates and hoods the direction
of the current set up by the heating of the water and the motion
imparted by the steam bubbles from the point of formation to the
surface of the water are directed into a channel, and a longitudinal
and elliptical flow of water takes place and is maintained as long
as heat is being transmitted to the water.
The Eckliff circulator is quite different. It consists of specially
formed and constructed tubes bent to conform to the curved surfaces
of the furnaces. These tubes run vertically from the bottom
of the boiler to the tops of the furnaces, and then horizontally
along the tops, being in contact, with the entire length of the furnace
except for one foot at each end, where the tube is bent upward at
an angle which causes the water to discharge directly against the
tube sheet just above the furnace. The playing of the water against
the plates prevents the cracking of the furnace flange or the com-
bustion chamber plate at the point where the two are riveted
together.
Another device often installed is a hydrokineter. This comprises
a steam jet and series of nozzles, and is placed near the bottom of
the boiler, thus driving upwards the cold water that collects there
and causing it to circulate. The steam required for its use is fur-
nished by another boiler.
Fusible Plugs. — Every boiler other than those of the water
tube type shall be fitted with at least two fusible plugs. They
must be so installed that the end of the banca tin on the water end
of the plug is not less than one inch above the dangerous low water
level. (See U. S. Steamboat-Inspection Rules,)
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380 MACHINERY
Injectors and Inspirators are for feeding water to the boiler
both operating on practically the same principle, viz., the energy
of the steam in a relatively large pipe is concentrated on a small
jet of water, giving it a high velocity and pressure that is sufficient
to overcome the boiler pressure, to open the check valves and
to force the water into the boiler.
WITT* iuPPLf TO mttiLEn
Figure 59. — Injector (Penberthy Injector Co., Detroit, Mich.).
An inspirator differs from an injector in the fact that it has two
tubes, one for lifting the water and the other for forcing it into
the boiler. An inspirator handling cold water with a short lift,
will work through a range of over 200 lb., while with water at 100° F.,
and a small lift, it will work through a range of from 150 to 200 lb.
The capacity of an injector should be about 30% in excess of the
maximum requirement of the boiler. A boiler horse power is the
evaporation of 30 lb. of water per hour, adding 30% to this; then
the required injector capacity would be about 40 lb. or 5 gallons
per hour for each boiler horse power. By multiplying the number
of boiler horse power by 40 lb. or 5 gallons, the capacity of the
injector in pounds or gallons is obtained. When the boiler horse
power is not known it can be approximated. See paragraph on
boiler horse power.
With cold water and a moderate lift, say not exceeding 6 or
8-ft., a good automatic injector will start up with 25 or 30 lb. steam
pressure, and will work with little or no further adjustment over
a range of perhaps 100 lb. pressure. With feed water at about
100° the same injector would start at 30 or 35 lb. and would work
up to about 100 lb.
Working on the same principle as boiler injectors are bilge ejectors
which are used in drainage systems, see page 611.
Digitized
by Google
HYDROMETER 381
Hydrometer. — The density of water can be determined by an
instrument known as a hydrometer. This instrument is placed in
the water to be tested and the distance it sinks noted, and readings
made from a scale on the side. Average sea water contains about
one part in 32 of solid matter, and hydrometers are usually gradu-
ated relative to this as a unit. That is, 2 on the scale indicates
twice as much solid matter relatively as sea water; 3, three times
as much and so on; while 0 indicates fresh water. The density of
the water depends on its temperature so that the scale on the hy-
drometer can only be used with the temperature that it is graded
with, which is usually 200° F. Sometimes three scales are provided,
viz., 190°, 200° and 210°. The water is drawn from the boiler
into a slender vessel called a salinometer pot, into 'which after
the water has cooled to the temperature (190°, 200°, etc.) on the
scale of the hydrometer, the hydrometer is placed in it, and the
density of the water determined.
Superheaters may be classed: (1) separately fired, i. e., those
using the hot gases from a source other than the furnaces of the
main boilers; (2) those utilizing the gases from the boiler on their
way to the stack; and (3) those utilizing the gases which have not .
left the main boiler evaporating surface. The two latter are more
popular than the first.
The above classes may be divided structurally into the tubular,
which requires the steam to pass through tubes for a greater part
or all of its path during which heat is added, and the cellular, which
requires the steam to pass through a chamber of irregular shape
and to receive heat from gases flowing through tubes which pass
through the steam chamber.
An example of Class 2 as applied to a Babcock and Wilcox water-
tube boiler is shown in Fig. 57. Here the superheater is placed
in a box that is arranged to form a continuation of the first and
second passes of the gases of combustion as they pass around the
tubes of the boiler. In order that the steam as it passes through the
superheater may be thoroughly exposed to the hot gases, removable
baffles or division plates are put in the headers of the superheater,
two in the upper header at one-quarter of the length from each end
and one in the lower header at mid-length. The result of this
location of the baffles is to force the steam as it goes through the
superheater tubes to pass through the hot gases 8 times. The
superheater tubes are 2 ins. in diameter and are arranged in groups
of 4, accessible from a single handhole.
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382
MACHINERY
Figure 60. — Foster Superheater.
Fig. 60 is a return bend element with connection headers of a
Foster superheater (Power Specialty Co., New York, N. Y.). Any
number of these elements may be connected together, the number
depending on the quantity of steam to be superheated, the amount
of superheat and the temperature of the gases that will strike the
elements. Each element consists of a seamless drawn steel tube,
on the outside of which are cast iron gills or flanges close together,
the mass of metal acting as a reservoir for heat. Inside of the
nvJ^v^
TESTS OF STEAMERS
383
elements are wrought iron tubes centrally supported by knobs or
buttons. These inner tubes are closed at the ends. A thin annular
passage for the steam is thus formed between the inner and outer
tubes, the steam clinging closely to the heating surface and is
quickly heated.
Of Class 3 is the Schmidt, which when applied to Scotch boilers
consists of collector castings and a system of units or elements
made of U-bent cold-drawn seamless steel pipes. The collector
castings are placed in either a vertical or a horizontal position
and located in the uptake end of the Jx>iler. The units are arranged
in groups leading in and out of the uptake end of the boiler tubes
and are expanded into flanges or collars which are in turn fastened
to the collector castings. In joining the ends of the unit pipes
to the collector castings one end of the pipe is in communication
with the header from the boiler and the other with the steam pipe
leading to the engine. Thus the steam in passing from the boiler
to the engine must pass through the units in the tubes, where
the superheating takes place. The most economical results are
Tests op Steamers Equipped with Superheaters
Engine
I.h.p.
Draft
Fuel
Super-
heat in
Degrees
Type of
Boiler
Super-
heater
Name of Steamer
Economy
in
Per cent.
Per
I.h.p.
J.C. WaOaee
U.S.S. M iehigan...
U.S. S. Carolina...
Odin
Quad-
ruple exp.
Triple
Triple
Triple
Quad.
Triple
Triple
Triple
Triple
1,589
16,016
17,651
900
4,027
2,005
2,600
1,600
1,925
Induced
Forced
Forced
Natural
Howden
Howden
Natural
Howden
Natural
6.7
12.8-15
16.5
1.646
1.51
1.395
1.303
1.29
1.454
1.322
1.10
1.20
88
85.7
47.5
2ii"
266"
Babcock
A Wilcox
Babcock
A Wilcox
Babcock
A Wilcox
Scotch
Scotch
Scotch
Scotch
Scotch
Scotch
Babcock
A Wilcox
Babcock
A Wilcox
Babcock
A Wilcox
Schmidt
Port Lincoln*
Port Augtuta
Schmidt
Schmidt
Schmidt
Schmidt
Schmidt
* Port Lincoln, steam pressure 220 lb., temperature of steam 600°.
t Ferrona, steam pressure 180 lb., temperature of steam 580°.
From Marine Steam. Babcock & Wilcox Co.
obtained from the Schmidt superheater with a temperature of
from 580° to 620° F. Between these temperatures it is claimed
that in a quadruple expansion engine the consumption will be from
10 to 12%, in triple expansion 12 to 18%, and in compound engines
ile
384
MACHINERY
from 18 to 25% less than in similar engines using saturated steam
and operating under the same conditions.
Superheated Steam, see section on Steam.
Feed Pumps, see Pumps.
Boiler Covering, see Insulating Materials.
Ash Ejectors. — Here the ashes are dumped into a hopper having
a pipe curved at the upper end to a large radius that passes through
the side of the vessel above the water line. To the hopper is a
water connection from a pump, and by turning on the water the
ashes are discharged overboard. The gallons of water required
to operate ash ejectors are about as follows:
Size of discharge pipe
Inches
3^
6
Gallons of water per minute
required to operate
120 to 180
160 to 240
210 to 360
Figure 61.— Ash Ejector.
Fig. 61 is of an ash ejector built by Schutte & Koerting, Phila.,
Pa. H is the hopper into which the ashes are emptied, and A is
the cock for turning on or off the water. The valve L admits air
yGoogk
OPERATING 385
only into the discharge pipe when the ejector is in operation and
closes automatically when the discharge is stopped.
Instead of the above, on large steamers the ashes are raised in
bags by a small steam engine and then dumped overboard.
Operating. — The amount of water fed to a boiler should be as
uniform as possible. When getting under way open all the check
valves to the same extent and test all the water gauges. The feed
check valves should be adjusted afterwards to give the requisite
uniform supply to each boiler. The feed stop valves should always
be wide open when water is being fed into a boiler.
As to the temperature of the feed water the U. S. Steamboat-
Inspection Rules state: "Feed water shall not be admitted into
any marine boiler at a temperature less than 100° F., and every
such boiler except donkey boilers, shall have an independent aux-
iliary feed appliance for supplying said boiler with water in addition
to the usual mode employed, which auxiliary feed shall enter the
boiler through an opening and a fitting which are entirely inde-
pendent of the fitting and opening for the main feed."
Should any difficulty be experienced in feeding a boiler, the
combustion should be checked at once by closing the dampers and,
if necessary, ash pit doors. Should the water get below the lowest
try cock and out of sight, the fires should be extinguished and then
hauled.
Always deaden fires before hauling, which can be done by throw-
ing on wet ashes. Fire extinguishers should be handy, which could
be used in case of emergency.
Firing. — The intervals between successive charging of furnaces
should be such that only a moderate amount of coal, not more
than three shovelfuls, is required at each charging to keep the
fires at the required thickness. In the U. S. Navy this interval
has been found to be between four and five minutes. The rate of
firing should be regular and some system of time firing be adopted.
The fires must be maintained at an even thickness. They
should not be less than 6 ins. thick for natural draft, and may
be increased to 12 ins. for heavy forced draft. The draft and air
supply, as well as the thickness of the fires, should be regulated
to suit the rate of combustion.
With a strong draft and very fine coal, it is sometimes desirable
to dampen the coal before firing it, to prevent its being carried up
the smoke pipe before being consumed.
The fires should be cleaned at regular intervals and the cleaning
Digitized by VJiOOQLC
386 MACHINERY
•
should be started as soon as the fires show a tendency to become
dirty, usually within 12 hours after starting the fires. Fires should
be cleaned one after another, with a regular interval of time be-
tween. It is bad practice to clean several fires at practically the
same time.
Shutting Off Boilers. — Fires should never be hauled except to
prevent damage to a boiler in case of emergency. When steam is
no longer required, fires must be allowed to die out in the furnaces,
with the dampers, furnaces, and ash pits closed.
When a boiler is to be shut off, internal accumulations of dirt
should first be removed by use of blow-out valves, and the boiler
then pumped up again to the usual level, unless it needs emptying
to carry out any repairs. Emptying by blowing down must never
be resorted to.
Boilers, when not under steam or open for examination, should
be kept full of fresh water of between three and four per cent, of
normal alkaline strength. The boiler should be pumped full
within 24 hours of completion of steaming, and should be kept so
until 24 hours before being required for steaming purposes. Even
if the boiler is to be examined within a few days of completion
of steaming, the water should not be allowed to remain at working
height, but the boiler pumped full.
When it is not practicable to keep idle boilers full of fresh water,
they should be emptied, their interiors thoroughly dried out, and
open trays as large as possible be filled to about half with quick-
lime and introduced through the manholes into the upper and lower
parts of the boiler. The boiler must then be closed airtight and
special precautions taken to prevent any moisture entering the
interior.
Overhauling Boilers. — Whenever a boiler is laid up for a complete
cleaning and overhauling the following operations should be carried
out:
Clean fireside and overhaul all furnace fittings, brickwork, baf-
fling, and fire parts.
Empty, open, and wash out the water spaces with fire hose.
Clean and inspect the water side and overhaul zincs (if installed)
and internal fittings.
Rinse out with fresh water and close the boiler.
Overhaul all valves, gauges, cocks, and other fittings.
Examine and repair all parts of the lagging, casing, and seating.
Apply hydrostatic test for tightness of valves, gaskets, etc.
Digitized by vjOOQ 1C
CLEANING TUBES 387
Test for tightness under steam, including tightness of casing,
and adjust safety valves.
Cleaning by Air Pressure. — For partially cleaning the fire side
of boilers, put a comparatively heavy air pressure on the fire rooms
shortly before the fires die out, opening the boiler dust doors but
having ash pit and furnace doors closed- This cleans the tubes
and casings. Close all Sources of air supply to the furnaces, and
keep them closed until the boiler is cooled. The above can only
be done when the wind is abeam.
Precautions in Opening Steam Drum. — After the boiler is empty
see that the steam stop, feed and blow valves, and any other valves
or cocks by which steam or water can enter the boiler are closed.
Insure a complete absence of pressure by opening the air cock
and test and water gauge cocks. Take off the manhole plates
and ventilate the boiler for a sufficient time to allow all foul air
to escape, and let no one enter the boiler until it has been ascer-
tained that the air is pure. Owing to the possibility of the presence
of an explosive mixture of hydrogen and air in boilers fitted with
zincs, the air in the boiler must be diffused before applying an open
light.
Washing Out Boilers.— Use a hose with water at a pressure of
at least 50 lb. Take the hose into the steam drum and wash out
the circulating tubes; that is, if the boiler is a water tube boiler.
The washing out shoulo\ be done as soon as possible after emptying,
and before the sediment left in the tubes, nipples, and boxes becomes
hardened.
Cleaning Tubes. — Clean the tubes with swabs, bristle brushes,
wire brushes, or scrapers, unless their condition indicates the ne-
cessity of using turbine cleaners.
Hard scale containing much sulphate of lime and magnesium
can be removed from the boiler tubes with a turbine water cleaner
using water at a pressure of about 125 lb. per square inch. The
following has given good results:
Sal soda 40 lb.
Catechu 5 lb.
Sal ammoniac 5 lb.
Boiling Out. — The amount of boiler compound to be used and
the time required for boiling out depends on the nature and amount
of the dirt present. If an inspection after 24 hours continuous
Digitized by VjiOOQ 1C
388
MACHINERY
boiling shows that the scale is still hard, the boiling should be con-
tinued.
In boiling out, introduce steam from another boiler to the lower
part of the boiler, allowing the excess to blow off through the safety
valves or air cocks at about 40 lb. pressure. If it is impracticable
to use steam from another boiler, maintain very light fires and
carry only enough pressure in the boiler *to insure circulation. If
heavy fires are maintained there is danger of overheating a dirty
boiler:
Causes op Scale and Remedy
Troublesome substance
Trouble
Remedy or Palliation
Sediment, mud, clay, etc. . .
Readily soluble salts
Bicarbonates of lime,., mag-
nesia, iron
Incrustation
Incrustation
Incrustation
Incrustation
Corrosion
Priming
Corrosion
Corrosion \
Corrosion
Filtration; blowing off
Blowing off
Heating feed. Addition
Sulphate of lime
of caustic soda, lime or
magnesia, etc.
Addition of carbonate of
Chloride and sulphate of
soda, barium chloride,
etc.
Addition of carbonate of
Carbonate of soda in large
amounts
soda, etc.
•Addition of barium
Dissolved carbonic acid and
oxygen
chloride, etc.
Heating feed. Addition
Grease (from condensed
steam)
of caustic soda, slaked
lime, etc.
Slaked lime and filtering
Carbonate of soda
Organic matter (sewage) . . .
Substitute mineral oil
Precipitate with alum or
feme chloride and filter
Operating and Overhauling oontain abstracts from pamphlet published by the
U. S. Navy Department, also from Care of Naval Machinery. H. C. Dinger.
DRAFT
Natural draft is caused by the difference of weight in the heated
air of the uptake and the cold air entering the furnace. To obtain
a good draft the funnel and uptake temperatures must be between
600° and 700° F., this temperature being necessary to bring about
the required difference of weight of air.
Digitized by LiOOQ 1C
DRAFT 389
Heat Absorbed in Creating Natural Draft. — The specific heat
of the funnel gases is about .23, which means that to raise one
pound of the gases 1° in temperature, .23 of the heat unit (B. t. u.)
is necessary. The example given below shows the loss incurred
by the generation of natural draft.
Example. Cold air temperature 62°, uptake temperature 700° F., and allowing
24 lb. of air per pound of coal: calculate the heat units per pound of coal used in
producing the draft.
700° — 62° = 638° increase of air temperature
B. t. u. required - 638° X (24 + 1) X .23 - 3,668.5
The quantity (24 + 1) =24 lb. of air +. 1 lb. of coal - 25 lb. of gases in
all neglecting ash and clinker.
Assume that 1 lb. of coal contains 14,500 B. t. u., or 100%
Then 14,500 : 3,668.5 = 100% : x% and x - 25%
Thus 25% of the heat units in each pound of coal are used up
in producing the necessary difference in temperature of the funnel
gases required to form a draft by difference of weight.
For Increasing the Draft to a Boiler, one of four means may be
employed:
(1) Closed fireroom; air forced by blowers into the fireroom
which is closed airtight except for the inlets to the furnaces. A
static pressure of % to 3 ins. of water is maintained according to
the rate of combustion required.
(2) Closed ash pit; the air in the stoke hold is at the same
pressure as the outside atmosphere, the air handled by the blowers
is led through ducts, and after passing over tubes heated by the
waste gases from the boiler the air is delivered to the ash pits under
pressure. An allowance of 4.5 cu. ft. of air per minute at atmospheric
temperature per pound of coal burned per hour is usually enough
and represents the provision of 270 cu. ft. of air per pound of coal.
A well known type of this system is the Howden.
(3) Exhaust fan in uptakes or between them and the funnel.
Represented by the Ellis and Eaves induced draft system, in which
an exhaust fan draws the gases along the uptakes and discharges
them into the funnel. Assuming that the products of combustion
reach the fan at 550° F., a capacity of 9.33 cu. ft. of gases per
minute per pound of coal burned per hour should be allowed, this
being equivalent to 560 cu. ft. of gases per pound of coal.
(4) Steam jets in the funnel.
Data from Mechanical Draft, Am. Blower Co.
Measurement of Draft. — Draft is measured by a U-shaped tube
located in the fireroom, one end of* which is open to the air pres-
* Digitized by v^iOOQIC
390
MACHINERY
sure in the fireroom and the other connected by an iron pipe to
the space under the grates. The difference between the two pres-
sures causes the water to rise and fall in the tube. On the side
of the tube is a scale with fractions of an inch marked. Instead of
the U tube a steam gauge having a graduated scale from 0 to 5 lbs.
may be used for forced draft.
A column of water 27.66 ins. high exerts a pressure of one lb. per
sq. in. Thus if the reading is 3 ins., then the pressure of the draft
3
is 0>7 gg = .108 lbs. per sq. in. If the pressure at the fan is 2J^
ins., the pressure under the fire bars is about Y% in.
Velocity Created When Am Under a Given Pressure Escapes
Into the Atmosphere
Pressure in
Velocity of
Air in Feet
Pressure in
Velocity of
Pressure in
Velocity of
Inches
Inches
Air in Feet
Inches
Air in Feet
Water
per
Water
per
Water
per
Gauge
Second
Gauge
Second
Gauge
Second
.1
20.7
1.5
80.1
2.9
111.2
.2
29.3
1.6
82.7
3.0
113.0
.3
35.8
1.7
85.2
3.1
114.9
.4
41.4
1.8
87.7
3.2
116.7
.5
46,3
1.9
90.1
3.3
118.5
.6
50.7
2.0
92.4
3.4
120.3
.7
' 54.7
2.1
94.7
3.5
122.0
.8
58.5
2.2
96.9
3.6
123.8
.9
62.1
2.3
99.1
3.7
125.4
1.0
65.4
2.4
101.2
3.8
127.1
1.1
68.6
2.5
103.3
3.9
128.8
1.2
71.6
2.6
105.3
4.0
130.4
1.3
74.6
2.7
107.3
1.4
77.4
2.8
109.3
From Mechanical Draft. B. F. Sturtevant Co.
Air Required. — The amount of air admitted to the furnaces
should be regulated so that little or no smoke issues from the stacks.
To find out about the combustion get an Ellis tube and test a
sample of the smoke gases for carbon dioxide. Perfect combustion
produces about 16% carbon dioxide in the stack gases. If the
instrument shows 14% the combustion is very good but if it drops
to 6, there is either too much air going through or not enough.
Another chemical is put in the tube and another sample tested
for carbon monoxide. If over 3% shows, it is fairly certain that
there is not enough air tinder the grate bars. If there is only *
Digitized by VJiOOQlC
, BLOWERS
391
trace of carbon monoxide then there is too much air. There are
on the market recording devices which automatically take and
test samples of stack gases and trace a curve, which on a large ship
is a valuable index of how the firing is being done, and shows at
what times the firing was bad.
The actual amount of air passing into the furnaces is usually
not less than 18 or 20 lb. per pound of coal and may considerably
exceed this amount. At 12.5 cu. ft. per pound (that is, 12.5 cu. ft.
of air weighs 1 lb.) this would give the volume of air required per
pound of coal from 225 (18 times 12.5 cu. ft.) to 250 cu. ft. See
table Quantity of Air Required for Combustion of Fuel.
Blowers. — There are a number of types on the market having a
variety of design of runners or wheels. One that has given excep-
tionally good results is the Sirocco, which consists of long narrow
blades on the periphery of a wheel, curved forward in the direction
of rotation and mounted parallel to the shaft. The blowers are
driven by electric motors, by high speed steam engines running
at 250 to 700 r. p. m., or by steam turbines. See Ventilation.
Figure 62. — Fan Rotor.
On account of the high speed it is important that all parts be
properly lubricated. The speed at which the blower is to run is
regulated by the water tender and is governed by the air pressure
Digitized by VjiOOQIC
392
MACHINERY
that is to be maintained. The engines require a periodical adjust-
ment of the working parts, and they should be tried at least once
a month if the vessel does not ordinarily run on forced draft. Care
must be taken that the doors of the casings, oil service, etc., are
absolutely dust tight, and that no dust or dirt can get on the
bearings.
When two or more turbine-driven high speed fans are in the
same fireroom, the speed of each fan must be practically the same
to obviate the fans' working against each other. The fan speeds
may be adjusted by a single valve at each turbine and all fans
slowed down or speeded up, as conditions require, by the manipu-
lation of one valve supplying steam to all the turbines.
Below is an abstract from the specifications for 9 turbine units
for the U. S. battleship California: "Each blower to be of the
multivane, centrifugal cased double inlet type capable of dis-
charging continuously with ease 23,000 cu. ft. of air per minute
with an average pressure at the boiler fronts not exceeding 4 ins.
Fans Built for Forced Draft Installations as Installed on
Various Steamers
(B. F. Sturtevant Co., Hyde Park, Mass.)
Cubic
Revolu-
Diameter
Feet per
tions per
Size of Fan
of Wheel
Driver
Minute
Minute
Inches
16,000
400
90 ins.
54
6X5 vertical single-cylinder
5X4 vertical double-cylinder
16,000
'6,000
475
No. 9 multivane
40
350
* 119 ins.
66
6X5 vertical single-cylinder
18,000
450
100 ins.
60
6X5 vertical single-cylinder
18,000
450
No. 9 multivane
40
6X5 vertical single-cylinder
20,000
325
120 ins.
72
7X6 vertical tingle-cylinder
25,000
350
120 ins.
72
7X6 vertical single-cylinder
25,000
325
130 ins.
78
7X6 vertical single-cylinder
25,000
450
No. 9 multivane
40
7X6 vertical double-cylinder
30,000
500
No. 9 multivane
40
5X4 vertical double-cylinder
30,000
300
140 ins.
87
8X8 vertical single-cylinder
35,000
400
No. 10 multivane
47
8X7 vertical single-cylinder
17,000
900
No. 6 multivane
23
20 h. p. electric motor
23,000
1,000
No. 7 multivane
28
30 h. p. electric motor
40,000
700
No. 8 multivane
34
45 h. p. electric motor
20,000
2,000
No. 60 turbovane
25
Steam turbine
20,000
1,600
No. 6 multivane
23
Steam turbine
30,000
1,500
No. 80 turbovane
39
Steam turbine
Where the size of the fan is given in inches the fan is always of the steel plate
type. The diameter of the inlet on steel plate fans is about seven-tenths the
diameter of the wheel and the diameter of the inlet on multivanes and turbovanes
is about 85% of the diameter of the wheel. The outlet, while of rectangular form,
generally has an area about equal to the inlet area.
Digitized by VJiOOQLC
MARINE STEAM ENGINES , 393
of water. Each blower will be driven by a direct connected steam
turbine, coupled direct to the fan shaft by a flexible coupling.
The turbine to be of sufficient power to run the blower at full capacity
with a steam pressure of 200 lb. gauge, but will be strong enough
to run continuously at 280 lb. with 50° F. superheat and with a
back pressure of about 10 lb. The steam consumption per brake
horse power under operating conditions not to exceed 45 lb. per
hour."
Miscellaneous Notes
The size of coal must be reduced and the depth of the fire increased
directly as the intensity of the draft is increaseds
The frictiorial resistance of the surface of the funnel is as the
square of the velocity of the gases. Ordinarily from 20 to 30%
of the total heat of combustion is expended in the production of
the stack draft, to which is to be added the losses by incomplete
combustion of the gaseous portion of the fuel, and the dilution of
the gases by an excess of air, making a total of fully 60%.
One square foot of grate will consume on an average 12 lb. of coal
per hour under natural draft.
Temperatures. —
Furnace temperature about 2600° F. .
Combustion chamber 1500° F.
Uptake 750° F.
Funnel 600° F.
In some torpedo boat destroyers the hatches to the fireroom
are made with two doors, viz., an upper and a lower, so that the men
on entering and leaving will not cause a loss of pressure in the fire-
room.
MARINE STEAM ENGINES
Marine steam engines are of the vertical type for screw propul-
sion, and beam or inclined for paddle wheel. The boiler pressure
for compound engines is about 120 lb., for triple expansion 140 to
180, and slightly higher for quadruple. With a main steam pipe
of ample size and the throttle valve wide open, the initial pressure
should not be much lower than 5 lb. below the boiler pressure.
The mechanical efficiency of an engine is the ratio of the work
available at the propeller or at the paddle wheel to the work done
on the pistons, and is from 85 to 90%.
Vertical Engines. — When their length must be kept at a minimum
Digitized by vjOOQ 1C
394
MACHINERY
a tandem arrangement of the cylinders may be adopted; thus a
four-cylinder triple expansion engine may only have three cranks.
The following table gives the ways the cylinders may be supported.
Cylinder Supported By
Condenser
Class of Vessel
Cast iron column on one side to
condenser which forms part
of frame, other side has steel
columns to bed plate
Part of frame
Tugs and cargo
steamers
Cast iron A columns
Separate from
engine
Passengers and
cargo steamers
Steel columns
Separate from
engine
War vessels
To get the maximum work from the steam it is expanded in two
or more cylinders — sometimes in as many as four, as in quadruple
expansion — but the general practice in large engines is to have them
triple expansion with three cylinders; if with four, besides the high
and intermediate there are two low-pressure, and with five there
are one high, two intermediate and two low.
The ratio of the volume of the high-pressure cylinder to the
low in compound engines is about 1 to 4, and in triple expansion
1 to 7 or 1 to 7.25, the ratio to the intermediate being about 2.9.
The ratio of expansion is the ratio of the volume of the low-
pressure cylinder up to the point of release and including the clear-
ance to the volume of the high-pressure cylinder up to the point
of cut-off including the clearance. Taking the high-pressure cyl-
inder as one, then the ratio of expansion in compound engines
ranges between 5 and 7; for triple expansion between 8 and 12;
and for quadruple expansion between 12 and 15.
The valve controlling the admission of steam to the high-pressure
cylinder is generally of the piston type, to the intermediate a single-
ported or double-ported slide valve, and to the low pressure a
double-ported slide valve. The great advantage of a piston valve
lies in the fact that it is perfectly balanced in regard to the steam
pressure.
The power developed in each cylinder depends on the cut-off
of the steam by the valve. The total horse power can be altered
by changing the high-pressure cut-off or the initial pressure. To
Digitized by VJ OOQ 1C
EXPANSION
395
Figure 63.— Piston Valve,
cut down the horse power of an engine, it is considered more eco-
nomical to cut off earlier in the high-pressure cylinder than to lower
the initial pressure by throttling. (See table of Steam Used Ex-
pansively, page 405.)
Expansion,
Cut-off and Back Pressure.
Type of Engine
Initial
Pressure
at Engine
Absolute
Nominal
Expan-
sions
High
Pressure
Cut-off.
Back Pressure
in lbs. per sq. in.
Low Pressure
Cylinder
Triple expansion naval
Triple expansion merchant
Quadruple expansion merchant .
165
to
200
165
to
185
190
to
210
6
to
9
to
12
12
to
14
.7
to
.8
.65
to
.75
.65
to
.75
5
to
7
5
to
6
5
to
6
(From Marine Engine Design, by Bragg.]
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396
MACHINERY
The order in which the cranks pass the top center when the
engine is going ahead, to a person standing forward and looking
aft, is called the crank sequence. Crank sequences are given
starting with the forward cylinder. Thus in a triple expansion en-
gine with the cylinders arranged with the high pressure forward,
then the intermediate, and then the low, the crank sequence is
generally high pressure, intermediate pressure, and low pressure;
and with a four-cylinder triple, high pressure, forward low pressure,
intermediate pressure, and then low pressure.
In compound engines the cranks are 90° apart; in three-cylinder
triple 120°; and in a four-cylinder often 90°. ' Designers as far as
possible endeavor to have each cylinder develop the same power,
and by a suitable arrangement of the cranks and moving parts
to have the engine balanced so that no parts are unduly strained
or overloaded.
The distance between the piston and the bottom or top of the
cylinder at the end of the stroke is the linear clearance. This is
usually about \i of an inch or so at the top and % of an inch at the
bottom, the clearance always being more at the bottom to allow
for the wearing down of the bearings.
The general design of an engine depends on the trade in which
the vessel is to engage. For torpedo boats and other craft where
Figure 64.— Slide Valve.
Digitized
by Google
PADDLE-WHEEL ENGINES 39?
high speed is essential, engines running at 400 or more revolutions
per minute are not uncommon. Here the cylinders have a compara-
tively short stroke and there are at least four. For merchant Vessels
revolutions are decreased, the stroke is longer, and the cylinders
are larger per horse power developed.
To secure economy in the consumption of steam and hence of
coal, the steam, after leaving the low-pressure cylinder, passes
into a condenser (see Condensers). In the case of surface conden-
sers they often form part of the engine framing. The back pressure
on the low-pressure piston for condensing engines is about 3 lb.
per square inch absolute, and for non-condensing 18 lb. absolute.
Paddle-wheel Engines. — These can be divided into two classes,
viz., those driving steamers with the wheels on the side and those
driving steamers with wheels at the stern.
Side-wheelers either have the engines inclined with the connecting
rods working directly on the crank shaft, or vertical with the con-
necting rod connected to a walking beam from which is a rod that
drives the wheel shaft. When the engines are inclined there are
two or more cylinders and the steam works expansively. When
vertical there is only one cylinder having a stroke of several feet.
(See Excursion Steamers and Paddle Wheels.)
Simple beam engines have double poppet valves, generally
with fixed Stevens' cut-off and in some cases with adjustable Sickles'
dash-pot cut-off. Double trip shafts for raising the main and
exhaust valves are on the larger engines, one trip shaft being for
hand use and the other for operation by steam, as may be desired.
When the boat is maneuvering, or approaching or leaving a pier,
the main valve eccentric gear is disconnected.
The main valves of the inclined engines for paddle steamers
are usually of the double-beat poppet type, although in some cases
there is a balanced slide valve on the high-pressure and double-
ported slide valves on the low-pressure cylinders. Stephenson
link gear is usually employed although the Walschaert gear has
given excellent results. Piston valves have been extensively used.
The main air pumps may be worked by the main engines. The
condensers, feed water heaters, filters, and auxiliaries are of the
customary types1. While jet condensers, in combination with water
purifiers, in the past have been installed mostly on the Great Lakes,
in recent years surface condensers have been adopted.
Stern-wheel vessels are largely used on the Mississippi and
other western rivers in the United States, and on shallow rivers
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398
MACHINERY
Figure 65. — Double-Ported Slide Valve.
in Africa and South America. In the United States the engines
have horizontal cylinders relatively small in diameter, with a long
stroke. The peculiar feature is the valve gear, the valves being of
the double-beat poppet form, and each cylinder (one on each side
Digitized by VjiOOQIC
VALVES
399
of the steamer) is provided with four, two for steam and two for
exhaust, the valves being&perated by a cam mechanism.
Valves. — Different types are shown in Figs. 63, 64, 65 and 66.
The chief advantage of a piston valve is that it is perfectly balanced
as regards the steam pressures which act upon it. Since a flat
slide valve is forced against its seat by the pressure of the steam
on its back (which pressure is equal to the difference between the
pressure in the receiver and in the cylinder), there is a heavy f no-
tional load to be overcome by the eccentric acting through the
valve stem. To keep the heads of a piston valve tight, packing
rings are provided. In some cases where a piston valve takes
Figure 66.— Allan's Valve.
Digiti
zed by G00gk
400
MACHINERY
steam on the outside the steam is led to the chest at one end only,
and then passes to the other end through the inside of the valve.
In such cases the body of the valve is hollow, and as large as pos-
sible.
Fig. 64 shows a single-ported valve that covers but one set of
ports.
Fig. 65 is a double-ported slide valve. With this valve the area
of the port opening required may be obtained with a travel of
valve only one-half that for a single-ported valve, or with the
same valve travel twice the area of the port opening may be se-
cured. It is for this reason that a double-ported valve is often
selected when it is desired to obtain a relatively large opening with
a small travel of the valve.
Trick's or Allan's valve (Fig. 66) gives a much quicker opening
and also a longer duration of full opening than a plain slide valve.
It is often used on compound engines.
A triple expansion engine with cylinders 16 H, 25 and 43 ins.
in diameter by 30 stroke had the following valves:
Cylinder
Valve
Size of Port Openings
High
pressure
Intermediate
pressure
Low
pressure
Piston (Fig. 63)
Slide (Fig. 64)
Double-ported
Slide (Fig. 65)
Rectangular port openings spaced
around a circle 7 ins. in diameter.
The openings being 1% ins. high,
with % in. of metal between them
Port openings on cylinder starting
at top of cylinder, 1J^ steam, 33/g
exhaust, ll/& steam by 24 ins.
wide. Valve faces, top 3J^,
opening 5%f lower face 3% by
24 ins.
Port openings on cylinder starting
at top iy8, iy8, ±y2, \y8 and 1%
by 3 ft. 5 ins. Valve face 3J4
opening 2%. face 1J4, opening
1%, face Zy8) opening 7, face 3J/g,
opening \%} face 1J4, opening
2%, face 3M, by 3 ft. 5 ins. wide
Lap and Lead. — Figs. 67 and 68 are sections through a slide valve
and cylinder showing lap (Fig. 67) and lead (Fig. 68).
y Google
VALVE TRAVEL
401
In Fig. 67, A B steam lap = edge of valve extends over edge of,
port on steamjaide
C D exhaust lap = edge of valve extends over edge of
port on exhaust side
In Fig. 68, A B steam lead = distance port is uncovered to steam
C D exhaust lead = distance port is uncovered for
exhaust.
Valve Travel. — The travel of a valve is equal to (steam lap -f
port opening) X 2. The following data is of a cargo steamer
with an engine
27 X 46 X 76
48
, 2360 i. h. p., high pressure receiver
180 lb., intermediate 55 lb., low pressure 16 lb., r. p. m. 63, vacuum
27 ins., speed 11.2 knots.
Expansion
Valve
Travel
Lead
Steam Lap
Port Opening
CutrOff
Top
Bottom
Top
Bottom
Top
Bottom
Top
Bottom
HIGH, PRESSURE PISTON VALVE
Ins.
.72 (full gear) 7
v«
%
1A
VA
l»Vi«
2
Z5H
33H
Digitized by Vji vJvJ V LV^
402
MACHINERY
Valve
Travel
Lead
Steam Lap
Port Opening
CuWJff
Expansion
Top
Bottom
Top
Bottom
Top
Bottom
Top
Bottom
INTERMEDIATE PRESSURE DOUBLE-PORTED SLIDE VALVE
.65 (full gear)
6
H
K
m
1H
m
IX-
33tf
29K
LOW PRESSURE DOUBLE-PORTED SLIDE VALVE
.53 (full gear)
8
H
A
2H
2A
IX
1*
2SH
22H
Abstracts from Verbal Notes. J. W. M. Sothern.
Valve Mechanism. — The most satisfactory valve mechanism
for vertical marine steam engines is the Stephenson. With it the
direction of rotation of the engine may be changed at will, and the
point of cut-off varied by varying the travel of the valve.
The Stephenson valve mechanism or link motion consists of
two eccentrics, viz., ahead and astern, with a link connecting the
ends of the eccentric rods that are fastened to the eccentric straps
Figure 68.— Lead.
Digiti
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SLIDE VALVES
403
on the engine shaft, so that by varying the position of the link the
valve stem may be put in direct connection with either eccentric
or may be given a movement controlled partly by one eccentric
and partly by the other. When the link is moved by suitable levers
into a position such that the block to which the valve stem is at-
tached is at either end of the link, the valve receives its maximum
travel and when the link is in mid-position the travel is the least
and the cut-off takes place early in the stroke.
The expression "open and crossed eccentric rods" is under-
stood to mean the position of the eccentric rods when the crank
is on the bottom center, as in running the rods open and cross each
other alternately. For slide valves or outside steam piston valves
the rods are usually arranged as open, but with inside steam piston
valves the rods are fitted so that they are crossed when the crank
is on the bottom center. This is to obtain the full benefit of link
expansion, for if the rods were arranged the reverse way the lead
would be diminished when linked up, and the range of expansion
more limited.
Effects of
Linking Up (Slide Valves)
Arrangement of Eccentric Rods
Valve
Travel
Lead
Cut-Off
Release
Com-
pression
Open rods (crank on bottom)
Crossed rods (crank on bottom) . . .
Reduced
Reduced
Increased
Decreased
Earlier
Earlier
Earlier
Earlier
Earlier
Earlier
The disadvantages of Unking up are: excess wire drawing of
steam, due to reduced port opening, and rapid increase of com-
pression, which reduces the effective area of the indicator diagram.
In the ordinary shifting link with open rods, the lead of the
valve increases as the link is moved from full to mid-position, that
is, as the period of steam admission is shortened. The variation
of lead is equalized for the front and back strokes by curving the
link to the radius of the eccentric rods concavely to the axes. With
crossed eccentric rods the lead decreases as the link is moved from
full to mid-position.
The linear advance of each eccentric is equal to that of the valve
in full gear, that is, to the lap plus the lead of the valve when the
eccentric rods are attached to the link in such position as to cause
half the travel of the valve to equal the eccentricity.
Digitized by VjiOOQIC
404 MACHINERY
The angle between the two eccentric radii, that is, between
lines drawn from the center of the eccentric disks to the center
of the shaft, equals 180° less twice the angular advance.
Setting of Valves, — Whether a valve is properly set or not can be
readily told by taking indicator cards (see Indicator Cards). Many
engines are supplied with steel laths marked with the setting of the
valves and these are used to verify the position of the valves.
To measure the lead of a valve, put engine on center with link
in full gear and measure the steam port opening for that end. If
this distance corresponds with the lead given on the drawing, the
valve is set as designed. The cylinders of large engines have
peepholes covered with bolted plates, by removing which the valves
may be observed. A long thin wooden wedge is inserted in the
opening as far as it will go, the edges of the opening leaving a mark
on the wedge which is the measure of the lead. When the marks
left by either end are alike the leads are alike. '
Owing to the wear on their collars, valves will drop, thus de-
creasing the lead at one end, and increasing it at the other. If
the valve takes steam on the outside, a dropping down of the valve
will increase the lead on top and decrease it at the bottom.
To bring the valve up into the proper position, distance pieces
may be put above the shoulder of the valve stem, or liners placed
under the valve stem. This takes into account the dropping
down of a valve due to wear, and hence the shortening of the valve
stem. Valves may also be changed by shifting the nuts holding
the valve.
To Find the Steam Pressure in a Cylinder at the End of the
Stroke. — Boyle's law states that the pressure of a gas varies in-
versely as the volume if kept at a constant temperature.
Let P = absolute pressure in pounds
V = volume in cubic feet
C = constant
Then PXV = C)P = yyV = y
Example. The initial pressure in the high pressure cylinder of an engine is 185
lb. gauge pressure, the cut-off . 6. Find the theoretical pressure at the end of the
stroke.
P = 185 +15 (atmospheric pressure) = 200 lb.
C = P X V = 200 X .6 = 120 lb.
C 120
Then the absolute pressure P2 = -— = — - = 120 lb., and 120 — 15 lb. (atmoa-
Vi 1
pheric pressure) =» 105 lb. gauge pressure.
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STEAM CONSUMPTION 405
Table of Steam Used Expansively
Initial
Average Pressure of Steam in Lb
. per Square
t Which Ste
j Inch for the Whole
Pressure
Stroke. Portion of Stroke a
,am is Cut Off.
Lb. per
Square
Inch
H
H
M
H
X
Vs
30
28.9
27.5
25.4
22.2
17.9
11.5
35 '
33.8
32.1
29.6
25.9
20.8
13.4
40
37.5
36.7
33.8
29.6
23.8
15.4
45
43.4
41.3
38.1
33.3
26.8
17.3
50
48.2
45.9
42.3
37.
29.8
19.2
60
57.8
55.1
50.7
44.5
35.7
23.1
70
67.4
64.3
59.2
52.4
41.7
26.9
80
77.1
73.5
67.7
59.3
47.7
30.8
90
86.7
82.6
76.1
66.7
53.6
34.6
100
96.3
91.8
84.6
74.1
59.6
38.4
110
106.
101.
93.1
81.5
65.6
42.5
120
115.2
110.2
101.5
89.4
71.5
46.1
130
125.4
119.1
110. .
95.3
77.5
50.
140
134.9
128.6
118.5
103.8
83.3
53.8
150
144.7
137.8
126.4
111.2
89.4
57.7
160
153.6
147.
135.4
118.2
95.4
61.5
180
173.5
164.6
152.3
132.9
107.3
69.2
200
192.7
183.7
169.3
148.3
119.3
76.9
To Find the Number of Expansions by Pressures and by Volumes. *
,„ . Hieh-pressure initial pressure absolute , -
(1) ^ — - — r = — f u — r~r - number of expan-
Low-pressure terminal pressure absolute
sions by pressures.
,rt. Low-pressure ratio , - , '
(2) „. , — „ = number of expansions by volumes
High-pressure cut-off ^ J
Example. Find the total number of expansions by pressures in a triple expan-
sion engine, if the high-pressure cylinder has an initial pressure of 165 lb. (gauge)
and the low-pressure cylinder a terminal pressure of 12 lb. absolute. Also the
number of expansions by volume if the cylinder ratios are 1:2.7:7.2, and the
high-pressure cut-off is r 6
166 lb. + 15 lb. (atmospheric pressure) =■ 180 lb. abs.
,, .„. High-pressure initial pressure absolute 180 -
By (1) = 7~zr- — i , , . = -T7T - 15 expansions by pressure.
Low-pressure terminal pressure absolute 12
(2)
Low-pressure ratio
i712
.6
12 expansions by volume.
High-pressure cut-off
High-Pressure Cut-Off and Coal or Steam Consumption.* — The
consumption (either coal or steam), and therefore the horse power
* Int. Marine Engineering, New York.
Digitized by VJiOOQLC
406 MACHINERY
developed, vary as the cube of the speed of a steamer at moderate
speeds. As the high-pressure valve cut-off is the approximate rate
of steam consumption and therefore of the coal consumption, then
the variation in cut-off for a given speed may be approximated as
follows :
Example. The speed of a steamer is 12 knots, with the high-pressure cylinder
cut-off . 6. Find the high-pressure cut-off required to reduce the speed to 11 knots.
12' : 11' = .6 : x (the new cut-off)
1728 : 1331 = .6 : x
x = .46 the new cut-off
Indicator Cards* are important not only for calculating the
indicated horse power (i. h. p.) but also for giving information on
the work done in a cylinder. An ideal card is shown in Fig. 69.
RS is the line of zero pressure (called the absolute pressure line),
from which all pressures are measured upward according to the
scale of the diagram. A is the beginning of the downstroke, B
the point of cut-off, C the point of exhaust, and D the end of the
stroke. The line AB is the steam line and shows the steam pres-
sure on the upper side of the piston from the beginning of the stroke
to the point of cut-off. The line BC is the expansion line and
shows the decreasing values of the pressure during that part of the
stroke. At C the exhaust opens and the pressure drops suddenly
as shown by CD.
For the return or upstroke, D is the beginning, E the point of
exhaust closure or beginning of compression above the piston, and
F the point of steam opening just before the beginning of the next
downstroke.
CD is the exhaust line and shows the nearly constant pressure
during the exhaust period. EF, the compression line, shows the
increasing pressure on the return stroke after the closing of the ex-
haust valve. FA, the admission line, shows the sharp jump upward
as the steam valve is opened, just before the beginning of the next
downstroke.
The line PQ is drawn when the space below the indicator piston
is shut off from the engine cylinder and connected to the air; it
is the atmospheric line. The distance between RS and PQ repre-
sents the pressure of the atmosphere, viz., 14.7 lb. per square inch.
Thus for the downstroke the varying pressures on the top of the
piston are shown by the varying distances from RS to ABCD,
* From Practical Marine Engineering.
Digitized by LiOOQ 1C
DIFFERENT CARDS
407
/c/ecr/ Care?
Figure 69. — Indicator Cards.
while for the upstroke the pressures on the same side of the piston
are shown by the distance from RS to DEFA.
Analysis of Different Cards (Figs. 69 -and 70). — (1) Eccentric too
far from a line at right angles to the crank; i. e., angular advance
is too large.
Digitized by LiOOQ LC
408 MACHINERY
Results. Cut-off too early, steam lead large, exhaust opening
and closure early. Whole cycle of events is ahead of time.
(2) Eccentric too near a line at right angles to the crank; i. e.,
angular advance is too small.
Results. Cut-off too late, steam lead small or negative, com-
pression small, steam opening late, exhaust opening and closure
late. Whole cycle of events behind time.
(3) Steam lap too large.
Results. Cut-off early, steam opening late, and lead small or
even negative, port opening small with a probable wire drawing
of the steam and drop of pressure on the steam line.
(4) Steam lap too small.
Results. Cut-off late, steam opening early and lead large and
port opening" large.
(5) Exhaust lap too large.
Results. Exhaust closure early and compression large, exhaust
opening late and exhaust lead small.
(6) Exhaust lap too small.
Results. Exhaust closure late and compression small, exhaust
opening early.
(7) Excessive compression. The pressure in the cylinder may
be carried above that in the valve chest before the steam valve
opens, thus forming a loop as in Fig. 1. This may be due to either
(1) or (5)'.
(8) Excessive expansion (Fig. 7).
Results. The pressure in the cylinder may fall below that in
the next receiver or exhaust space beyond, thus forming a loop
as in Fig. 7.
(9) Valve stem too long (Fig. 8).
Results. The nrddle of the stroke of the valve is placed too
high relative to the ports. The results for an outside valve will
be to give too much steam lap on top and exhaust lap on the bot-
tom and too little steam lap on the bottom and exhaust lap on top.
Hence: steam opening in the top is late and small and the cut-off
early; steam opening on bottom is early and full and the cut-off late;
exhaust opening in the top is early and full and the closure late;
exhaust opening on bottom is late and small and the closure early.
(10) Valve stem too short.
Results. Similar to those in (9) but oppositely related to the
ends of the cylinder.
(11) Leaky piston or piston rod stuffing box.
Digitized by VjiOOQIC
INDICATOR CARDS
409
Figure 70. — Indicator Cards.
oogle
410 MACHINERY
Results. Expansion line will be steeper than it should be. Com-
pression line may also flatten off somewhat near the top.
(12) Port openings or passages too small.
Results. Wire drawing or loss of pressure on the steam line and
rise of pressure on the exhaust line.
To Calculate the Mean Effective Pressure and the Indicated
Horse Power. — Divide the curve obtained from an indicator into
say 11 even parts and measure the ordinates. Take the mean length
of all the ordinates, which will be in inches and a decimal, and
multiply it by the scale of the spring used in the indicator; the
result will be the mean effective pressure or P in the formula for
indicated horse power. , .
Let L = length of stroke in feet
A = area of piston in square inches
N = number of single strokes per minute or two times the
number of revolutions
P XLXA XN
Then indicated horse power (i. h. p.)
33,000
In estimating the mean effective pressure for any multiple ex-
pansion engine, it is customary to calculate the pressure that would
be required if the work were all done in the low-pressure cylinder.
This is called the mean effective pressure referred to the low pres-
sure cylinder, and the calculation for horse power then becomes
identical with the calculation for a single-cylinder engine. For
a compound engine the referred mean effective pressure is
M. E. P.. (referred) = low-pressure M. E. P. +
high-pressure M . E. P.
ratio low pressure to high pressure
and for a triple expansion engine
M. E. P. (referred) = low-pressure M. E. P. +
intermediate pressure M . E. P.
ratio low pressure to intermediate pressure
high-pressure M. E. P.
ratio low pressure to high pressure
Below is a table showing the arrangement for calculating the
i. h. p. The particular engines were installed in a twin-screw car
ferry. Each engine had cylinders 19, 31, and 53 ins. in diameter
by 36 stroke, piston valves on the high and intermediate cylinders
nvJ^v^
ENGINE FORMULAE
411
with a double-ported slide valve on the low, Stephenson link motion
air pumps attached to the intermediate crossheads, r. p. m. 92, and
runs jet-condensing.
Area
&
L'Rth
Ins.
Spring
M.
E.P.
Area
of
Piston
IJi.p.
Lh.p.
Lh.p.
Total
r
H.P.
Top
3.35
4.13
80
64.8
283.5
153.8
Starboard
H.P.
Bottom
2.88
4.13
80
55.8
267.6*
125.1
278.9
Engine ,
Int. P.
Top
2.13
3.75
40
22.7
754.8
143.1
Int. P.
Bottom
2.07
3.75
40
22.1
738.9*
136.5
279.6
L.P.
Top
3.58
4.20
10
8 52
2124
151.1
L.P.
Bottom
3.45
4.20
10
8.24
2108*
145.6
296.7
855.2
H.P.
Top
3.37
4.11
80
65.5
283.5
155.2
H.P.
Bottom
3.03
4.11
80
59.4
267.6*
132.8
288.0
Port Engine.-
Int.P.
Top
2.20
3.78
40
23.3
754.8
147.0
Int.P.
Bottom
2.18
3.78
40
23.1
738.9*
142.8
289.8
L.P.
Top
3.47
4.12
10
8.44
2124
150.0
L.P.
Bottom
3.40
4.12
10
8.26
2108*
145.7
295.7
873.5
Total
1728.7
* Assuming piston rod = 4^ inches diameter and no tail rods.
To Calculate the Coal Consumption per I. H. P. per Hour. — The
data necessary are: indicator cards from the engine, revolutions
per minute, and coal consumed during the run. From the indicator
cards the mean effective pressure may be determined and the
i. h. p. for one end of the cylinder can be calculated from the formula
PLAN
QQ n^ (where N is one half the number of revolutions), and of
the other end in the same way. The sum of the two gives the total
horse power for the cylinder. Knowing the pounds of coal con-
sumed per hour, this quantity divided into the total i. h. p. per hour
gives the pounds consumed per i. h. p per hour. See also Fuels.
Engine Formula
Estimated Horse Power.
• D = diameter of low-pressure cylinder in inches
S = stroke of piston in inches
P = absolute boiler pressure
R = revolutions per minute
Z = coefficient for warships 85,000
short passage express steamers. . . . 91,000
long passage express steamers 94,500
passenger cargo steamers 97,000
cargo steamers 105,000
Digitized by LiOOQ 1C
412 MACHINERY
Estimated Horse Power - D* X ^X - X R. This formula
gives a very close approximation to the horse power actually
indicated when at full speed.
From A Manual of Marine Engineering, A. E. Seaton.
Shafting. — A hollow shaft is stronger than a solid one of the
same sectional area. A shaft will stand twice as much torsional
stress as bending stress, the constant for torsion being 5.1 and for
bending 10.2.
Lloyd's Rules state: Diameter of crankshaft and of thrust
21
shaft under collars to be at least ^ of that of the intermediate
shaft (see table below); thrust shaft may be tapered down at each
end to same diameter as intermediate shaft. Diameter of screw
(tail) shaft to be equal to diameter of intermediate shaft X
.63 -f -~7p-) Dut m no case to.be less than 1.07 T, where P is
diameter of propeller shaft and T diameter of intermediate shaft
1 both in ins.
Let A = diameter of high-pressure cylinder in inches
B = diameter first intermediate-pressure cylinder in inches
C «■ diameter second intermediate-pressure cylinder in
inches
D — diameter low-pressure cylinder in inches
S — stroke of pistons
P — boiler pressure above atmosphere in pounds per square
inch
Diameter op Intermediate Shafts
Type of Engine
Diameter of Intermediate Shaft in Inches
Compound, 2 cranks at right angles . .
Triple, 3 cranks at equal angles . .
Quadruple, 2 cranks at right angles . .
Quadruple, 3 cranks
Quadruple, 4 cranks
(.MA + .006D+ .025) Xy^T
(.038 A + .009 £+ .002Z) + .01655) XJfiT
(.034i4+.011fi+.004C+0.0l4Z)+.0l6S) X^/J
(.028i4+.OUB+.006C+.0017i)+.015S) Xtyf
(.0334+.01B+.004C + .00132) +.01555) X^/p~
y Google
CYLINDERS 413
The number of collars on a thrust shaft is roughly one collar up
to 5 ins. diameter of shaft, and an extra collar for every 1.8 ins. dia.
or number of collars = 1 H ' \ Q f°r merchant vessels
1 . o
. , dia. shaft — 5 . .
= 1 H rr^ for war vessels
l.zo
To find the diameter of the collar,
D = dia. of collar
d = dia. of shaft
N = number of collars
P = allowable pressure in lb. per sq. in.
See Thrust Bearing.
Total thrust (T) = total area X allowable pressure
Y X N(D* — d*)XP
Then
D = 4/ t +d*
Thickness of collars = .4 (D-d)
Cylinders.— For ratio of diameters see page 294. If the cylinders
are to be steam jacketed then liners are necessary. For a cylinder
without a liner the following formula may be used.
t = thickness of walls in ins.
P = max. pressure in cylinder
D = dia. of cylinder
(P + 25) D 40
6000 "*" 100 + D
When a liner is used the inner surface of the cylinder barrel C
will have a diameter equal approximately to D -f- 2L -f 2J, where
D == dia. of the cylinder, L = thickness of the hner, and / = width
of jacket space, which is usually % or 1 in.
Connecting Rod. — Length 4J^ to 5 times the length of the crank.
Diameter at upper end same as diameter of the piston rod, area of
section at lower end 1.2 to 1.3 that of the piston rod.
D = dia. at middle of rod in ins.
L = length from center to center in ins.
K for merchant vessels = .028\/effcctive load on piston in lb.
K for war vessels =* .022veffective load on piston in lb.
Then D =*^ L * K
4
Digitized by LiOOQ 1C
414
MACHINERY
Piston Rod—
p = greatest pressure on piston in lb.
F = a coefficient — naval engines 50
merchant ordinary stroke 45
merchant long. stroke 42
merchant very long stroke 41
Dia.ofrod = Diaof;ylinderXx/p
Another formula for the piston rod diameter is:
gj /!• H. P. of one cylinder
V 2 X length of stroke X
length of stroke X rev. per mm.
Pistons. — Often of cast steel dished or conical in form and of a
single thickness of metal. The pistons of compound and triple
expansion engines should as a rule have the same total depth, thus
giving a steep angle to the high pressure and a flat to the low, the
latter being not less than about 1 : 5.
Bearing Surfaces. — Allowable pressure in lbs. per sq. in. of pro-
jected surface using mean loads.
Crank pin
Main bearings
Using Maximum Loads:
Slipper guides ....
Crosshead pins
Link block pin
Link block gibs . . .
Eccentric rod pins.
Drag rod pins ....
Eccentrics
Thrust collars ....
rchant vessels
Naval
200- 250
250- 300
200-350
250- 500
x>ads.
60- 80
70- 100
850-1200
1200-1800
750-1000
850-1200
250- 400
350- 500
700- 950
900-1100
500- 700
700- 800
150- 200
175- 225
50- 80
80- 100
[Several of above formulae from Marine Engine Design, by Bragg.]
Engine Fittings and Accessories
The Throttle Valve is for controlling the steam to the engine and
is attached to or placed close to the high-pressure cylinder. For
ease in quick operating some form of a balanced or power valve is
necessary.
Of the balanced type may be mentioned the double-beat, poppet,
the butterfly, and the balanced piston. The former has two disks,
the upper being slightly larger than the lower. The chief difficulty
is to keep the disks tight, as the variations in temperatures tend
JvJ^Vl^
BUTTERFLY VALVES
415
to seat the disks unequally. . Butterfly valves have an elliptical
disk with a spindle in the center. This type is well balanced but
is difficult to keep tight. Throttle valves with balance pistons
have such pistons attached to the valve stem, the piston working
in a cylinder in which steam is admitted, although the valve itself
is operated by hand.
Figure 71.— Throttle Valve. [Schutte & Koerting, Phila.]
Of the power type, this consists of a separate power unit oper-
ated by steam and connected by links to the throttle valve which
is controlled entirely by the power unit.
Cylinder Drains and Relief Valves. — As water collects in the
steam chests and cylinders, drains and relief valves are fitted.
The former are placed as low as possible, and are connected to a
common pipe leading to the bilge* or to the feedtank. Relief
valves serve as safety valves, relieving the cylinders from exces-
sive pressure by automatically opening and allowing the water to
be discharged.
Starting or Pass-Over Valves. — To assist in starting the engine,
particularly if the high-pressure crank is on or near the dead center,
Digitized by vjivJLJVLC
416
MACHINERY
a valve and pipe are provided for admitting steam direct from the
steam pipe or high-pressure valve chest to the first receiver or
intermediate valve chest. This will give sufficient load on the pis-
ton of the intermediate cylinder to start the engine. Either cocks
or small slide valves are used, that can be opened wide by a single
stroke of the lever.
Reversing Engine. — May be direct acting or the all around type,
usually the former. Diameter of reversing cylinder .185 to .2 the
diameter of the low pressure cylinder of the main engine. The
direct acting consists of a steam cylinder mounted on one of the
engine columns, that is, connected by rods to the links of the
Stephenson valve gear. The operating lever is located close to the
one on the throttle valve. Below is a table of sizes of reversing
and turning engines:
Engine
I.h.p.
17 X 27 X 44
1,000
4,000
4,100
4,800
30
2SH X 39M X 63
45
29 X 49 X 84
54
29^X47^X2-58
42
Reversing Engine
Turning Gear
9 ins. dia. X 16 ins. stroke
12 ins. dia. X 24 ins. stroke
14 ins. dia. X 24 ins. stroke
12 ins. dia. X 18 ins. stroke
Worm and wheel
Worm and wheel
Eng. 5 in. dia. X 6 in.
stroke
Twin-cylinder engine
each 4% ins. dia. X 5
ins. stroke
Turning Gear. — When steam is shut off, it may be necessary to
turn the engine. This is done by means of a large wheel, keyed
to the shaft or shaft coupling, that is driven by a worm gear, which
may be turned by hand or, as in the case of large engines, by a
small high-speed engine. See table above.
Steam Separators. — These are designed to remove water from
the steam, and to prevent it from entering the high-pressure cylinder.
This may be accomplished* by having the steam enter a casting
larger in diameter than the steam pipe, and causing it to make a
sharp turn around a baffle plate; or giving the steam a whirling
motion by having it come in contact with spiral plates riveted to
a cylinder. In the latter case, the particles of water are thrown
out by centrifugal force, falling to the bottom of the separator,
and are drained off to a trap.
Digitized by VjiOOQIC
J. LUBRICATING SYSTEM 417
Lubricating System.41 — Only the best oil, which has been filtered,
should be used. See Lubricating Oil. In many engines there is
a forced feed system, with a pump that is driven by the main engine,
small copper pipes leading to the guide faces, crank, and piston
ends of the connecting rods, and to the eccentrics. The main
bearings should be oiled so there is a film of oil between the shaft
and the Babbitt metal.
No internal lubrication of the cylinders is necessary other than
the swabbing of the rods and the wiping out of the cylinders and
vaselining them when they are opened. The addition of a small
quantity of graphite from time to time as the cylinders give indi-
cations of becoming dry is advisable, but when they have once
obtained a good surface there is no need of further lubrication.
Usually crank pins and eccentric straps should be oiled by hand
once every 20 minutes; main bearings, link gear, etc., once every
half hour. An inspection of the thrust bearing, spring bearings,
and stern tube gland should be made every half hour, and the piston
rods swabbed perhaps every 45 minutes.
For a triple expansion engine with cylinders 18, 29 and 47 ins.
diameter by 30 stroke, of 1,000 i. h. p., the following lubricating
equipment was specified: "A brass manifold shall be located on
each cylinder provided with wicks and brass tubes leading to prin-
cipal journals. Crank pins to be oiled by cups and tubes carried on
connecting rods and taking oil from drip overhead. Cross head
guides oiled by tubes leading from manifolds. Each eccentric strap .
to be oiled by cup and tube carried on the eccentric rod. Reverse
shaft bearings to be fitted with compression grease cups. A swab
cup shall be fitted to each housing for swabbing the piston rods
and valve stems. All fixed bearings shall have drip cups. All
moving parts shall have drip cups made of sheet brass, cast brass,
or copper with brazed seams.
Water Service. — The water is often supplied from the circulating
pump inlet and is pumped through the main bearing jackets and
cross head guides. The piping is of brass or copper. A hot bearing
is not always due to lack of lubrication or to a poor water service,
but may be caused by the shafting being out of line.
For a triple expansion engine of the size given under the heading,
Lubricating System, a water service as outlined below was speci-
fied. "From the main supply pipe there will be one H-inch branch,
with double swivel joint for each crank shaft bearing.
* Abstracts from Care of Naval Machinery. H. C. Dinger.
Digitized by LiOOQ 1C
418 MACHINERY
"Two %-inch pipes to each crank pin, extending across on each
side perforated on the bottom.
"One %-inch pipe to each cross head guide.
"One J^-inch pipe to each pair of eccentrics, with double swivel
joints.
"Two %-inch pipes to spring bearings.
"Each of the above branches shall have a separate valve and
shall terminate either on a pivoted nozzle or a permanent con-
nection to the part that is to be cooled, as required. All water
service pipes shall be of brass.
"The water service pipe shall be connected so as to be supplied
with sea water from the inlet chest of the salt water side of the
condenser and to the sanitary pump. There shall be valves at
these branches.
"There shall also be a steam connection for blowing out."
Thrust Bearing. — Directly aft of the crank shaft is the thrust
shaft and its bearing, the object of which is to prevent fore and
aft movement of the shafting due to the thrust of the propeller.
The thrust is taken care of by collars on the shaft that bear against
shoes on the thrust bearing that may be of cast iron, cast steel,
or brass with a bearing surface of white metal. The collars must
run in a bath of oil which is kept cool by salt water supplied by
the sanitary pump circulating in the bottom of the bearing.
217
The mean normal thrust = i. h. p. X -j-: — i — i i:
speed in knots per hour
The surface exposed to the thrust should be such that the pressure
per square inch does not exceed 80 lb., while for tug boats and
ocean-going vessels it should be about 50 lb. For the number and
diameter of the collars see page 413. The following is data on a
21H X 30% X 44M X 64 . _. . +, . 10 . ,. 4
=£ : engme. Diameter thrust 12 in., thrust
bearing of cast iron with cast iron shoes faced with babbitt and
fitted for water circulation; thrust pressure was taken by 4 collars
with unit pressure of 60 lb. per square inch.
Air Pump. — This may be driven by a lever, one end of which
is fastened to the upper end of one of the connecting rods of the
main engine or it may be independent. See Steam Plant Auxiliaries.
Line Shaft or Spring Bearings. — Their chief function is to sup-
port the shafting. They are of cast iron with a lower brass or
bearing piece fitted with white metal. - A bearing cap or cover
forms the top portion in which are grease cups or other lubricating
y Google
OPERATING 419
•
devices. In long lines of shafting the spring bearings are placed
on each side of the shaft couplings, being at a sufficient distance
so that the coupling bolts may be easily removed.
Engine Room Floors. — Preferably of wrought iron checkered
plates instead of steel, as the former will not polish so readily by
wear. These plates are supported by angle iron frames fastened
to the ship's frames. The most comfortable non-slipping floor
under the conditions of greasy surface and heavy weather is sheet
lead. The underlying wood platform should be laid so all joints
are smooth. The sheet lead is about 8 lb. per square foot or y% in.
thick, and is fastened down by copper nails. Care must be taken
not to put heavy weights directly on top of. the lead, but on mats.
Operating *
"About an hour before the time set for getting under way, start
to warm up the engine. The length of time depends on the size
of the engine, for large engines more than an hour may be required
and for small less.
"See that all tools, material, etc., are. clear of the engine.
"Start circulating pump, making sure that the injection and.
discharge valves are open.
"See that all parts of the engine are in place and properly se-
cured. Disconnect jacking gear.
"Start main air pumps and open main exhaust valves to con-
denser if these valves are fitted.
"Open bulkhead stops.
"Open drains to main steam line. Drain separator.
"Open boiler stop valves, just cracking them at first and then
open them gradually.
"Get reversing engine ready and turn steam in it.
"Turn steam on jackets and drain them. Open cylinder drains.
"The steam being up to the throttle, move links back and forth
with the reversing engine and crack open the throttle slightly.
This allows a little steam to pass into the high-pressure cylinder
and warms it up. Crack open pass-over valves to allow steam to
enter intermediate-pressure and low-pressure cylinders.
"Circulate water through thrust bearing and slides.
"See that feed pumps are in proper condition and try all that
are to be used.
* From Care of Naval Machinery. H. C. Dinger.
420 MACHINERY
"Make an inspection to see that there is plenty of steam, good
fires and everything about the engines is ready.
"Get permission to try engines 15 or 20 minutes before the
time set to be ready.
"Try engine both going ahead and astern and see that it re-
verses easily. Care must be taken not to open the throttle too
wide, otherwise the engine will develop sufficient power to break
the mooring lines if tied to a pier.
"The following causes may prevent the engine from working
satisfactorily:
"Water in Cylinders. This will prevent the piston moving its
full travel. The water must be got rid of by opening the drains,
and moving the piston back and forth by the reversing gear until
the water is out.
"Engine on Center. This can be guarded against by taking care
when the engine is stopped that the high-pressure crank is near the
middle of the stroke.
"Valve Rods Sticking. They may be loosened by applying oil,
loosening the stuffing box or the valve stem guide.
"Throttle must not be suddenly opened or closed but the engine
should be worked up to full power gradually.
"Reversing. The throttle should first be closed and engine
then reversed — under ordinary conditions. However, if the emer-
gency signal is received, the engine should be immediately reversed.
"When under way a great deal concerning the proper running
of an engine can be told by the sounds heard in the engine room,
as they tend to combine into a sort of rhythm, and from it the
experienced engineer can readily tell whether the different apparatus
is working properly.
"The chief sound is the heavy thump caused by the pounding
of the main bearings. This can be located by noting which crank
has just passed the center when the thump is heard. The main
bearing will have a duller sound than the crank pin or cross head.
The cross head knock is a sharper sound and is. not heard at so
great a distance.
"Often lost motion ran be told by feeling of the bearings.
"A valve loose on its stem or piston loose on its rod causes a
solid, sharp thump or a dull click.
"On starting up or slowing down, slide valves are apt to rattle
or cause a clicking sound due to lack of pressure on their backs.
Digitized by VJiOOQIC
TRIALS 421
"Pounding may be caused by: (1) Too much clearance in a
journal, slide or connection.
"(2) The use of too light oil on heavy pressure.
" (3) Power not equally distributed among the cylinders.
" (1) Can be remedied by readjusting and in part by slowing down
or changing the speed.
" (2) Use heavier oil.
"(3) Readjust the cut-off."
Trials
Noronic, passenger steamer, 362 ft. between perpendiculars, beam
molded 52 ft., depth m61ded'28 ft. 9 ins., engine 29^X474^X2~~58,
4 boilers each 15 ft. 6 ins. diameter by 11 ft. long.
Displacement 5,412 tons
Area, immersed midship section 776 . 5 sq. ft
Wetted surface 21,800. sq. ft.
Draft, forward 11 ft. 3 ins.
Draft, aft 18 ft. 1 in.
Draft, mean 14 ft. 8 ins.
Speed, miles per hour, average 17 . 43
Slip of propeller 11.6%
Steam pressure 192 . lb.
First receiver pressure 73 . lb.
Second receiver pressure 15 . 5 lb.
Vacuum 23 . 93 ins.
Revs, per min 106.
Indicated horse power, high-pressure cylinder 1,169.6
Indicated horse power, intermediate-pressure cyl-
inder 1,505.7
Indicated horse power, low-pressure cylinder aft . . . 711 .5
Indicated horse power, low-pressure cylinder for-
ward. 771.2
Total indicated horse power 4,158.
Mean effective pressure referred to low-pressure
cylinder 34.2 lb.
I. h. p. per sq. ft. of grate. 13.5
Sq. ft. of heating surface per i. h. p 3. 16
Temperature of injection water 40°
Temperature of hotwell 110°
Temperature of feed from heater 200°
Draft ins. of water at fans . . . 3 . 73
Trial lasted 6 hours.
Noronic owned by Northern Nav. Co., Sarnia, Ont. Built 1914.
Huron, freight steamer, 439 ft. 3 ins. length over all, on keel 416 ft.,
15 ^^r^
422 MACHINERY
k KAt* iaaa iuon^ • 19^X28^X41X60 .
beam 56 ft., molded depth 30 ft., engine -£- > ^wo
Scotch boilers each 14 ft. 9 ins. diameter by 12 ft. long.
Trial draft 18 ft. 6 ins. for'd and 19 ft. 6 ins. aft, and was loaded
with 4,660 tons.
Boiler pressure 208 . lb.
First intermediate receiver pressure 86. lb.
Second intermediate receiver pressure 37 . 5 lb.
Low pressure receiver pressure 9.1 lb.
Vacuum 21.2 ins.
R. p. m 84.9
Piston speed, ft. per min 594 . 3
Mean effective pressure, high-pressure cylinder 81.7
Mean effective pressure, first intermediate cylinder. 36.
Mean effective pressure, second intermediate cyl-
inder 14.97
Mean effective pressure, low-pressure cylinder 10.38
Mean effective pressure, referred to low-pressure
cylinder 34 .
Indicated horse power, high-pressure cylinder 440.
Indicated horse power, first intermediate cylinder. . 406.
Indicated horse power, second intermediate cylinder 356 .
Indicated horse power, low-pressure cylinder 529.
Total indicated horse power 1,731 .
Ratio i. h. p. to grate area 16.
Ratio heating surface to i. h. p 2.9
Temperature of injection water 56°
Temperature of stack 425°
Temperature of hot well 129°
Temperature of feed water 178°
Draft at fan, ins. of water 1 .57
Coal consumption per hour ..!...* 2,652. lb.
Coal consumption per i. h. p. per hour 1 .51 lb.
Speed in miles per hour 11 . 89
Trial 8 hrs. 17 mins. . "
Huron owned by Wyandotte Trans. Co., Wyandotte, Mich.
Built 1914.
U. S. Torpedo Boat Destroyer Cushingy 300 ft. between perpen-
diculars, 31 ft. 1 in. beam, 17 ft. 1 in. molded depth, twin-screw
Curtis turbines, 4 oil-burning Yarrow boilers, closed fireroom,
forced draft.
Displacement 1,048 tons
Draft 9 ft. 5 ins.
Speed 29. 183 knots
Main turbines developed a total of 15,280 h. p. at 576 r. p. m.
Evaporation of the boilers was 11.31 lb. per hour per sq. ft. of
Digitized by VJiOOQ 1C
CATTLE STEAMER 423
heating surface, 15.61 lb. per hour per shaft horse power and 12.46
lb. per hour per pound of oil.
Oil consumption 1.259 lb. per s. h. p.
Trial, 4 hours. Built 1915.
Cattle steamer, 435 ft. between perpendiculars, 46 ft. beam,
depth to main deck 37 ft. 11 ins., draft 27 ft. 10 ins., displacement
11,000 tons, wetted surface 36,050 sq. ft., draft to 27 ft. 10 ins.,
block coefficient .69, engine — 77^
1. h. p 2,600
R. p. m 53.7
Steam pressure 183 lb.
Steam first receiver 67 . 5 lb.
Vacuum 24 ins.
Speed 11.4 knots
I. h. p. per 100 sq. ft. wetted surface at 10 knots. . . 4.87
Coal burned per hour 4,390 lb.
Coal per i. h. p. main engine per hour . . . . 1 .68 lb.
Coal per sq. ft. grate per hour 17 . 1 lb.
The above data is the average of a 3,000 mile run.
Bristol } cargo steamer, 9,630 tons displacement, mean draft 24 ft.
. 23^ X 38^ X 67
9 ins., engme jr
I. h. p 1,795
R. p. m 75
Speed 10.78 knots
Vacuum * 27 ins.
Air pressure at fan 1.3 ins.
Average boiler pressure 162 . 5 lb.
Temperature of gases base of stack 496°
Trial 54 hours. 1916.
Pacific, cargo steamer, for dimensions see table of Turbine
Steamers. The trial lasted three hours at sea, with a full cargo of
8,300 tons aboard.
Draft 25 ft.
Speed •. 11.5 knots
Horse power 2,655.
R. p. m 87.
Steam at turbine 207 lbs.
Temperature superheated steam (F.) 420°
Temperature saturated steam 385°
Temperature feed water 180°
Temperature in stack 672°
Vacuum . . 28 ins.
Pounds of oil per horse power hour ; . 875
B. t. u. per horse power hour 16,420.
Digitized by VjiOOQIC
424 MACHINERY
City of St. Louis j passenger and freight, 397 ft. between per-
pendiculars, 49 ft. 6 ins. beam, gross tonnage, 6,200, engine
26 X43 X72 4 gcotch y^fe^ g^am allowed 180 lb. At 61.8
r. p. m., steam 130 lb., engine developed 1,219 i. h. p.
Lb. of steam per hour 15,276
Lb. of steam per rev 4 . 12
Lb. of steam per i. h. p. (1,219) 12.5
Propeller thrust 16.82 tons
At 80 r. p. m., steam 155 lb., engine developed 2,843 i. h. p.
Lb. of steam per hour 30,816
Lb. of steam per rev 6 . 42
Lb. of steam per i. h. p. (2,843) 10.8
Propeller thrust 35. 55 tons
At a boiler pressure of 152 lb., the intermediate receiver pressure
was 23 lb. gauge, and low pressure 1.5 lb., vacuum 28 ins., barometer
reading 29.7 ins., revs, of engine 67.3, i. h. p. 1,386.51.
Ocean Steamship Co., New York.
Steamer built in 1910, above data in 1914, on a trip from Norfolk
to New York.
PROPELLERS
Definitions.* — A propeller is right- or left-handed as it turns
with or against the hands of a watch when looked at when stand-
ing aft and the ship is being driven forward.
The face or driving face of a blade is at the rear. It is the
face that acts on the water and so receives»the forward thrust.
The back of a blade is the forward side.
Leading and following edges of a blade are the forward 'and
after edges .respectively when going ahead.
The pitch is the longitudinal distance which a vessel would
travel at one revolution of the propeller, were the propeller to
revolve in an unyielding medium, as, for example, in a fixed nut.
' The diameter is the diameter of the circle swept by the tips of
the blades.
Pitch ratio is the pitch divided by the diameter. For ordinary
reciprocating engines the pitch ratio is from .8 to 1.4, but in nearly
all turbine installations it is .8 or .9.
For high speed vessels the blades are elliptical in shape, with the
greatest breadth *about one third from the tip. For towing the
blades are very broad at the tips.
* Abstracts from Practical Marine Engineering.
Digitized
by Google
PROJECTED AREA 425
The developed area or helicoidal area of a blade is the actual
surface of the driving face.
Projected area is the area of the projection, on a transverse
plane, of all the blades. In large ships it is usual to design the
propellers for a pressure of not over 12 lb. per square inch of pro-
jected surface.
Disk area is the area of the circle swept by the tips of the blades.
The area of the propeller tip circle divided into the total ex-
panded blade area is known as the expanded area ratio or disk
area ratio, and is usually .3 to .4, but in propellers for turbines
the ratio varies from .4 to .8 owing to the necessity for crowding
the required blade surface into a small disk area. Below is a
formula for calculating disk area ratio.
Let R — revolutions per minute
D = diameter of propeller in feet
H — horse power per propeller
S = speed in knots per hour
C = coefficient of .30
The disk area ratio - C + jJLgJ/5^
In the table on page 426 the calculated D A R (disk area ratio) was
calculated with a coefficient of .30, and it will be noted that the
results obtained are very close to the actual disk area.
Number of Blades. — Three blades for warships and four for
merchant. If the dimensions of a three-blade and a four-blade
wheel are the same, it will take 25 to 30% more power for the same
number of revolutions to drive the four-blade than the three. Two
blades are objectionable on account of the excessive vibration
caused by them.
Cavitation. — This is the failure of supplying water to a propeller,
due to excessive blade velocity; in other words the speed of the
blades exceeds the speed of the water flowing to them, therefore
the effective thrust falls off in proportion, as cavities form at the
sides of the blades.
Slip. — The apparent slip is the difference between the speed
of 'the propeller and of the vessel. As a propeller works in a yield-
ing medium the speed of the vessel is less than the speed of the
screw.
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426
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V
REAL OR TRUE SLIP 427
Let v ■■ speed of the screw
V «- speed of the ship
v — F « slip of the screw
0— V
slip of the screw expressed as a fraction of the speed of the
screw
v — V
Then X 100 = percentage of slip
Example. A propeller having a pitch of 15 ft. and making 100 revolutions per
minute would advance 1,500 ft. per minute without slip. If the actual speed of
the ship is 12 knots, she would travel 12 X ' ~ ■ — 1,215 ft. per minute. The ap-
00
* 285
parent slip is therefore 1,500—1,215 = 285 ft. per minute or . __. =■ . 19 or 19%.
l,oUU
The real or true slip is somewhat different from the apparent
slip, in that the passage of the ship through the water causes
* some of the water astern to follow the ship. This current of water
is called the wake, and its speed is dependent upon the shape of
the afterbody of the ship. Since this current is moving in the
same direction as the ship, the distance that the propeller advances
through the moving water in a given time will be less than if the
water were still. The slip through the moving water, or wake,
is called the real or true slip, and is greater than the apparent slip.
Suppose that the wake had a speed of 10% of the ship (it ranges
from 10 to 20%), or 122 ft. per minute. The propeller would then
advance through the wake at a speed of 1,215 — 122 = 1,093 ft.
per minute, and the real slip would be 1,500 — 1,093 = 407 ft. per
407
minute, or ^-—^ = .27 or 27%.
l,oUU
The difference between real and apparent slip may be expressed
thus:
1 - Sr = (1 - SJ (1 - W)
Where Sp = real slip
= apparent slip
For the case noted above 1 - Sr - (1 - .19) (1 - .10) = .81
X .9 = .729. Therefore Sr = .27 or 27%.
The apparent slip varies from 5 to 30%, the average being about
10. Owing to the slip a propeller must be run at a higher number
of revolutions than would otherwise be the case.
Digitized by LiOOQ LC
428 MACHINERY
Example. In a certain ship the revolutions of the engine averaged about 78 a
minute. The wheel was 14 ft. 6 ins. diameter and 15 ft. pi&h, the speed of the
steamer being 10 knots. Find the slip of the screw.
_, x i- • Pitch X r. p. m. — speed in ft. per min.
The apparent slip is = ... .,
* * pitch X r. p. m.
15 - 78 . 134 or about 13H%.
Formulae for Finding Slip, Speed, Revolutions, and Pitch of
Propellers.*
Where p =* pitch of propeller in feet
N = revolutions per minute
V = speed in knots of ship
s = slip ratio (that is, the apparent slip in per cent)
(1) To find the slip, having given the pitch, revolutions, and speed
in knots.
_ p N - 101.3 V
8 ^N
(2) To find the speed, having given the pitch, revolutions, and
slip. •
v = e N (1 - s)
101.3
(3) To find the revolutions, having given the speed, pitch, and
slip.
101.3 V
N -
To find the pitch
lutions.
V (1 - s)
(4) To find the pitch, having given the speed, slip, and revo-
101.3 V
N (1-s)
Approximate Rule for Finding the Pitch of a Propeller. — The
pitch of a propeller will equal the length of a circumference at the
place where the slope of the face is 45°, or where it is equally in-
clined to the shaft and to the transverse direction. Starting near
the shaft, the inclination to the longitudinal is small, but increases
toward the tip, passing at some point through the value of 45°.
At this point let the radius be r. Then the pitch of the propeller
is equal to 2 X 3.1416 X r very nearly.
* From Practical Marine Engineering.
Digitized by LjOOQ IC
TURBINE SHIPS m
To Find the Helicoidal and Projected Area of a Propeller in Place.
— Stretch a large piece of ordinary brown manila paper smoothly
over the driving face of one blade and press it down around the
edges to get the contour. Trim the paper to the crease and calcu-
late the area either by the trapezoidal or by Simpson's rule. If
by the former and one breadth is located at the extreme tip, the
area is the sum of half the tip and hub breadths plus all the others,
multiplied by the distance radially between successive 'breadths.
The projected area may be determined from the developed area
with a reasonable amount of accuracy by either of two formulae, the
first proposed by S. Barnaby and the second by D. W. Taylor, chief
constructor, U. S. N.
/-, \ t*_ • x' j Developed area
(1) Projected area = — -
4/1+ .0425 Pitch
Diameter
(2) Projected area = Developed area 1 1.067 — yr: - — 1
The first is not accurate for pitch ratios (pitch divided by diam-
eter), varying much from 1. The second holds over a range of pitch
ratios from .6 to 2, which is all that is customarily met with.
To Find the Thrust of a Propeller upon the collars of a thrust
shaft, use the formula:
m A , ., A. , h. p. of engine Xpropeller efficiency X33000
Total thrust in pounds = — - -f-= — - . . £ ~
speed of vessel in feet per mmute
See also Thrust Bearing.
Example. A 120 h. p., internal combustion engine running at 450 r. p. m. drives
a boat at 20 miles an hour. What is the total thrust in pounds upon the thrust
collars.
Assume the propeller efficiency is about 60% and substituting in the above
formula,
120 X .6 X 33,000 2,376,000
20 X 5,280 1,760
60
1,350 lb. which is the total thrust.
Wheels for Turbine Ships.
R =s revolutions of the screw per minute
V = speed of the vessel in knots per hour
S. h. p. = shaft horse power developed in the shaft and deliv-
ered to the screw
Digitized by LiOOQ IC
430
MACHINERY
E. T. P. =* effective thrust power = S. h. p. X suitable factor.
The effective thrust is the power required to propel
the vessel and is equal to the S. h. p. times a
coefficient varying from .55 to .52. The effective
thrust in pounds is given by the formula.
S. h. p. on one shaft X 33,000 X .52 or .55
V X 101.3
Diameter of propeller in feet
__ \/ effective thrust in pounds
C
For value of C see following table.
Apparent slip of propeller per cent. = .0206 R + 12.
Pitch. — Suppose it is required to find the pitch of a propeller to
drive a ship at 23 knots, the turbines making 520 revolutions per
minute.
The apparent slip - .0206 X 520 + 12 - 22.712 per cent.
Speed of screw at 23 knots = 23 +
22.7
100
X 23 - 28.22 knots.
D.. , 28.22 X 101.3 _.ft,. K*ft.
Pitch =* p^r — 5.49 ft., say 5 ft. 6 ins.
Pressure per square inch of developed surface = .00563 R -f- 7.5
Type of Vessel
Speed
in
Knots
Revolu-
tions of
Turbines
per
Minute
E.T.P.
Apparent
Slip of
Propeller
Per cent
Pressure
per Sq. In.
on Devel-
oped Sur-
face in
Pounds
Ratio of
Developed
Surface to
Disk Area
C = Coeffi-
cient
S.H.P.
for
Diameter
Large ocean mail str . .
Intermediate mail str .
Cross channel steamer
Fine-lined fast vessel. .
24 to 25
21 to 23
24
28
190 to 200
330
500 to 550
750
.53
.55
.53
.52
16.5
18.8
20.5
27.5
8.75
9.35
10.3
11.72
.535 .
.73
23
24.6
25
30
Taper of shaft hole in boss to be not
shaft dia.
6
+ .6. Thickness of
Taper in Propeller Boss
less than % in. per foot.
Propeller Key.— Width of key
key = width of key X .5.
Propeller Nut.— Diameter of nut = shaft dia. at screw X 1.5.
Thickness of nut = shaft dia. at screw X .75. The nut is left
handed for a right hand propeller, and right for a left hand.
Digitized
by Google
MOTOR BOAT PROPELLERS
431
Motor Boat Propellers. — Those in the following table have three
blades. A two-blade should be about two inches larger in diameter
to hold the engine to the same number of revolutions as a three-
blade of the same pitch and style. The table is based on speed
wheels up to and including 35 ins. in diameter, while above this
size it is based on a towing wheel having broader tips.
Revolutions per Minute
Horse
Power of
300
400
500
Engine
Dia.
Pitch
Dia.
Pitch
Dia.
Pitch
Ins.
Ins.
Ins
Ins.
Ins.
Ins.
2
18
20
14
19
12
18
3
18
26
16
20
14
17J4
4
20
26
18
22^
16
18
5
20
30
20
20
16
20
6
22
24
20
25
18
19
7
22
30
18
30
18
22
8
24
30
20
27
18
25
10
26
30
22
273^
18
28
12
28
28
24
26
20
25
14
28
30
26
30
22
24
16
30
30
28
28
24
24
18
30
33
28
30
24
26
20
30
36
30
30
24
28
22
30
39
30
31J^
24
30
25
30
42
30
33
26
28
28
32
37
30
35
26
30
30
32
38
30
37^
26
32
32
32
39
32
31
28
30
35
34
39
32
32
28
32
38
34
40
34
32
30
30
40
34
41
34
33
30
31
42
34
42
34
34
30
32
45
34
43
34
35
30
33
50
38
38
36
33
30
35
55
38
40
36
34
30
37
60
40
38
36
35
30
39
65
40
40
36
36
32
33
70
40
42
38
36
34
32
75
42
42
38
38
34
34
80
44
42
38
40
34
36
85
44
44
40
38
36
34
90
46
44
40
40
36 v
36
95
46
46
42
40
36
38
100
48
46
42
42
■ 38
38
Digitized
by Google
r
432
MACHINERY
The areas of all three blades of the
are as follows:
speed and towing wheels
Diameter, Ins.
Area Speed Wheel in Sq. Ins.
Area Towing Wheel, Sq. Ins.
12
45
14
63
16
78
18
99
20
126
22
159
180
24
193
212
26
229
247
28
267
290
30
309
340
32
353
390
34
399
440
36
451
490
38
545
40
600
42
660
44
730
46
800
48
870
Above data from Columbia Brass Foundry Co., New York.
For larger wheels see table of Merchant Ships, also the table
on page 426.
Blade thickness if continued to shaft center line
/
shaft dia. 8
X constant 4 -f-.5. Thickness
number of blades X boss length
at tip =» constant .04 X propeller dia. in ft. + .4.
Diameter and length of boss = constant 2.7 X shaft dia. Boss
diameter varies from V4 to 1/6 propeller diameter, curve of boss radius
is taken with a radius equal to boss dia. X .8.
[Formula for Taper, Key, Blade thickness, etc., from Verbal Notes. J. W. M-
Sothern.]
Weights op Propellers
Weights of cast iron propellers are given in the table, but if the
weight of any other material is wanted it can be obtained by the
formula.
Weight of new wheel =
weight of cast iron wheel X weight per cu. ft. of new material
weight per cu. ft. of cast iron
The pitch is 1J^ times the diameter.
Digitized by
Google
SPEED TABLE
433
Dia., Ins. Two B
ades, Lb.
Three Blades, Lb.
Four Blades, Lb.
12
9
12
15
14
12
19
20
16
19
24
24
18
21
26
32
20
22
28
44
22
25
35
55
24
30
51
67
26
55
68
92
28
80
110
120
30 :
100
132
124
32
. . .
140
196
34
. . .
. . .
220
36
. . .
• . •
225
38
• . •
• . .
282
40
, . .
• . •
330
42
• • •
• . .
350
44
• . .
• . .
370
46
. . •
...
380
48
, . .
...
510
50
, . .
...
525
52
. .
. .
545
54
. .
...
575
56
. .
. . .
595
58
• «.
...
680
60
. .
...
900
62
. .
...
925
64
• •
.'. .
950
66
. •
1,050
68
. .
1,220
72
1,380
76
. . .
1,450
78
• . .
1,650
80
1,870
84
. . .
2,000
88
• . .
2,150
92
• . .
2,760
96
...
3,150
120
. .
...
5,600
144
. . .
7,600
150
...
8,450
Sheriffs Mfg. Co., Milwaukee
, Wis.
Speed Table. — This gives the speed in miles per hour of boats
with propellers of ordinary pitches at common engine speeds, and
also the percentages of slip and theoretical speed of the propeller.
Four speeds are given for each pitch at each engine speed, corre-
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435
Digitized
by Google
i
436 MACHINERY
sponding to .four percentages of slip. The percentage marked
"None" indicates no slip and is the theoretical speed of the pro-
peller. Thus a 20-inch diameter by 30-inch pitch wheel at 500
revs, per min. shows in the 30-inch pitch column a theoretical speed
of the boat as 14.2 statute miles per hour.
To find the percentage of slip for a boat traveling 10 miles per
hour, engine making 500 revs, per min., the propeller having a pitch
of 28 ins., follow the column for 28-inch pitch down to the line
500; 10 miles per hour is not shown by the percentage of slip for
10.61 miles is 20% and for 9.28 is 30%; therefore the percentage for
10 miles would be about 25%.
For a new boat, knowing the revolutions of the engine and the
desired speed in miles per hour, to find the pitch of the propeller,
first estimate the percentage of slip according to the type of boat
then for the known r. p. m. and percentage follow the line to the
right to the figure nearest the desired speed. Follow the column up
and the pitch will be found at the top.
PADDLE WHEELS
In the old type of harbor and bay steamers the wheels consisted
of iron frames with boards fastened transversely to them. The
present practice is to have feathering paddles, the bottom of the
floats being about one-third of the draft. The breadth of each
paddle in side wheelers is about one-third the breadth of the steamer,
while in stern wheelers the paddles are nearly the entire breadth.
. Formulae for Finding Slip, Speed, Revolutions, and Pitch of
Paddle Wheels.*
Where x - 3.1416
8 = slip ratio
V = speed in statute miles per hour
N — revolutions per minute
D =■ diameter of pitch circle
For the same properties as given under the section on Propellers.
/tx DN-88V
(1)* ~ *DN
(2) y m >Dy«)
(3) N mV
x D (1 - «)
• From Practical Marine Engineering.
Digiti
zed by G00gk
STEAM TURBINES
437
(4) D =
88 V
T N (1-8)
Immersion of floats should not be less than }/& their breadth and
for general service should be lA.
Number of floats .varies with the diameter. With fixed radial
floats the usual proportion is one for each foot of diameter, and ii
feathering, number of floats
Diameter -}- 2
60
/area
Breadth of float = A / ~T~
-r y^
V revolutions
Length of float
area
r
In practice, r, the ratio of length to breadth, is 4 to 5 with fixed
radial wheels and 2.6 to 3.0 with feathering.
Paddle Wheels
Diameter
Speed,
Knots
Indicated
Area of
to Centers
Revolu-
Horse
Paddle,
of
tions per
Slip .
Name
Power
Sq. Ft.
Paddles,
Minute
Feet
13.
717
12.55
23.9
21.8
.197
Nantucket
13.
902
19.56
18.9
29.0
.234
Uncatena
13.5
966
27.48
18.5
26.4
.141
Gay Head
18.3
2520
34.00
16.4
41.0
.155
18.3
2680
34.10
17.0
47.0
.265
18.8
3400
45.20
18.7
40.0
.170
Tashmoo
18.9
6472
48.00
24.5
33.3
.250
City of Erie
STEAM TURBINES
The fundamental difference in the operation of a reciprocating
steam engine and a steam turbine is that in the former the steam
does work by its pressure overcoming resistance, and in the latter
the steam does work by its kinetic energy.
In turbines the velocity of the jet or jets is utilized to produce
rotation of vanes. Velocity is produced in a steam jet only by
expanding from one pressure to a lower one, so that regardless of
the type of turbine there must always be a pressure drop to gen-
Digitized by vjiOOQIC
438
MACHINERY
erate the velocity which is utilized. The velocity imparted to
the jet may be utilized in two ways: (1) by impinging on a vane
and driving the vane by impulse; or (2) by driving backwards the
nozzle in which expansion has taken place owing to the reaction or
kick-back of the steam in coming to a high velocity from a low one
by expanding through the pressure drop. No. 1 is basic for impulse
turbines and No. 2 for reaction turbines. If a large pressure drop
is available, this means a high nozzle velocity, and in some cases
it is difficult to utilize efficiently a high velocity, so recourse is had
to making the pressure drop occur a small amount at a time, each
drop in pressure and attendant increase in velocity being but a
fraction of the over-all drop; this is known as pressure compounding.
The same result may be obtained by arranging several rows of
vanes so that each row takes out a certain fraction of the velocity
of the jet, as, for example, if a pressure drop of 150 lb. gives a
nozzle
SHggfflL—
MOVING VANES
<~Si mple Impulse (DcLaval)
NOZZLE
<«««««
MOVING
VANES
««««««*
NOZZLES
MOVING
VANES
<<<<<<<<<««
MOVING
VANES
•Pressure Compounding (Rateau, Zoclly and Hamilton*
Holzwarth)
Figure 72. — Arrangement of Vanea.
Digitized by LiOOQ 1C
PARSONS TYPE 439
nozzle velocity of 3,600 ft. per second, the peripheral velocity of
one row of vanes, to utilize all of it, would be 1,700 ft. per second,
but if there were four wheels, the velocity of each would be but
one-fourth of this, or 425 ft. per second. This is called velocity
compounding. (See Fig. 73.) Frequently both pressure and ve-
locity compounding occur in one turbine, as, for instance, the
Curtis type, where the turbine as a whole is of the compound pres-
sure type with each pressure stage of the compound velocity type.
There are no turbines of the pure reaction type in commercial
use. The turbine most commonly classed as of the reaction type is
the Parsons (see Fig. 74) in which there is a small pressure drop
in the first row of vanes, the reaction from which tends to cause
the vanes to rotate away from the direction of discharge. In the
next row the same action takes place, but the vanes being fixed,
the jet impinges against the following rows of moving vanes which
feel the compound effect of this impulse and the reaction due to
the further expansion through the second moving row. This cycle
is repeated throughout the rest of the turbine.
The usual number of expansions (this refers to large turbines
of the Parsons type) is four in the high-pressure turbine, and eight
in each low-pressure, the total number of rows of blades being the
same for each separate turbine. Thus if the high-pressure turbine
is made up of say four expansions, each containing 16 rows of
blades, then each low-pressure turbine will have eight expansions,
each containing eight rows of blades. A pair of rows, consisting
of one row of fixed and one of moving blades, is usually called a stage.
The sectional areas of the steam passages in Parsons turbines
increase from the high pressure end to the low, so advantage is
taken of the expansive properties of the steam.
(Above paragraphs from Int. Mar. Eng'g, 1916.)
In a modern triple expansion engine with cylinder areas of say
high pressure to low pressure as 1 is to 7.5, and with a cut-off in
the high pressure of one-third the stroke, the total number of steam
expansions would be 7.5 X 3 = 22.5. In turbines the expansions
of steam are much more than this, as 125 to 140 expansions are
readily obtained. With a high-pressure turbine having an initial
pressure of 150 lb. and a condenser vacuum of 29 ins. or back pres-
sure of say 1 lb., the steam would expand about 150 times. Thus
more work can be got out of the steam by the increased number of
expansions, and hence the importance of having a high vacuum
in the condensers.
Digitized by VjiOOQIC
440
MACHINERY
NOZZLt.
axr<«««<;
"MOVING
VANES
^tttt y y yyy ) n*€D *mt vanc$
(SMfflLT
_ MOVING
_ VANES
V Velocity Compounding (A. E. G. (Small), Electra
and Terry)
Figure 73.
Impulse turbines which are directly connected to generators
for lighting consist of a row of nozzles which are fixed and a single
row of moving vanes. For marine purposes they are not built
much larger than 250 Kw. (See section on Electricity.)
In turbines the velocity of the steam is about 300 ft. per second
or 18,000 ft. per minute.
An arrangement often adopted, in steamers of 400 ft. or so in
length, is to install five turbines, three for ahead and two for re-
verse running. There are three shafts with one propeller on each,
Notable Ships Driven by Parsons Turbines
Name
Length
Feet
Displace-
ment
in
Tons
Horse
Power
Steam Con-
sumption
per a. h. p.
Hour for All
Purposes
in Pounds
Speed
in Knots
When
Built
100
250
360
490
785
901
44 H
650
3,000
17,900
40,000
49,430
2,300
3,500
14,000
24,712
74,000
56,000
15.
16.
13.6
15.3
14.4
32.75
20.48
23.63
21.25
26.
24.
1897
King Edward *
ff.M.S. Amethyst
H.M.S. Dreadnought.
1901
1905
1906
1907
1914
* For further particulars see Turbine Ships.
the reversing turbines being placed within the low-pressure ahead
casings. When running ahead the reverse turbines revolve inertly
in a vacuum of 24 to 26 ins., and when going astern the ahead
Digitized by vjOOQLC
ARRANGEMENT OF VANES
441
turbines run in a vacuum. The transatlantic liner Maureiania has
four shafts and six turbines. The extreme outboard shafts are
driven by the high-pressure turbines, while the inboard are driven
by the low-pressure, forward of which are the astern turbines. An
arrangement of five turbines as installed in an English Channel
steamer is as follows: Speed 22 knotjs, shaft horse power 6,500,
boiler pressure 160 lb., high-pressure turbine 140 lb., low-pressure
zzlcs
TUl«U««JTT
~ MOVING
^ VANES.
«a«««arax*
r MOVING
\ VANES.
7TTymr»m»»
FIXED fiWOE VAHES.
NG
a««««(rc«+ — -gags
• Pressure Compounding with Velocity Compounding
(Curtis Marine Type and large A. E. G.)
JJJJJJMJMZJ™.
GUIDE VANES.
XSSSSSHSE!^
• MOVING VANES.
jjjjjss&xa?
FIXED GUIDE VANES-
XBS30ag3SHF
:movihova«e5
JJMJMJZXB
F 1*10 GUIDE VAN E3-
Reaction (Parsons)
Figure 74. — Arrangement of Vanes.
-MOVING VANES.
Digitized
by Google
442 MACHINERY
i
turbine port 20 lb., low-pressure starboard 20 lb., condenser vacuum
24}^ ins., low-pressure port astern turbine 23 ins. vacuum, and th.2
same for the low-pressure starboard astern, revolutions 630 per
minute, propeller pitch 4 ft. 6 ins., slip 21%.
Geared Turbines. — In recent practice the driving of the pro-
peller shaft by the turbine through intermediate gears has been
tried in both merchant and war vessels. By means of gearing,
a high-speed turbine occupying a small space can drive a large
diameter propeller at a slow speed. This arrangement admits of
economy at low ship speeds owing to the fact that turbines are
more efficient when running at a high speed and propellers at a low.
In single-screw vessels both the high-pressure and the low-pressure
turbines have pinions meshing directly with the gear on the propeller
shaft. Experience has shown that there is no reason to expect a
loss of energy of more than 1 J^ to 2% in the gearing and its bearings.
For cargo steamers of 15 knots or under, geared turbines have
pioved satisfactory. At higher speeds few have been installed.
Confining attention to vessels of the cargo carrying class at speeds
below 15 knots, the margin between the several methods of pro-
pulsion (see table on page 496) is so small that local or economic
conditions which have no bearing on engineering features are often
the deciding factors. Geared turbines undoubtedly operate on
increased steam economy, but there is little difference in the ma-
chinery weight and space, and the first cost is higher than recip-
rocating engines. Below is data on a cargo vessel driven by
geared turbines. See also table of Turbine Ships.
Cargo vessel, 275 ft. long, 38 ft. 9 ins. beam, 21 ft. 2 ins. deep,
draft 19 ft. 8 ins., displacement 4,350 tons. Two boilers 13 ft.
diameter by 10 ft. 6 ins. long, heating surface 3,430 sq. ft., grate
surface 98 sq. ft., steam 150 lb., natural draft, condenser cooling
surface 1,165 sq. ft.
Two turbines in series, one high pressure and one low, former
on starboard side and latter on port. High-pressure turbine 3 ft.
diameter by 13 ft. over all; low-pressure 3 ft. 10 ins. diameter by
12 ft. 6 ins., the reversing turbine being in the casing for the low.
Gear wheel (cast iron) on propeller shaft, 8 ft. 3^ ins- diameter
of pitch circle, 398 teeth double-helical with a circular pitch of
.7854. Total width of face of wheel 24 ins., inclination of teeth 20°
to the axis. Pinion shafts of chrome nickel steel, 5 ins. diameter of
pitch circle with 20 teeth, .7854 circular pitch. Ratio of gear to
pinion 19.9 to 1.
Digitized by LiOOQ 1C
GEARED TURBINES
443
Propeller wheel 14 ft. diameter, 16.35 ft. pitch, expanded area
70 sq. ft.
Speed by log 10.22 knots
Revolutions per minute 70 .6
Boiler pressure 140 lb.
High-pressure turbine, initial pressure Ill lb.
Vacuum in inches 28 .4
Barometer, inches 29 .88
Water, pounds per hour consumed by turbine. . . . 14,510 .
Shaft horse power 960 .
Water consumed in pounds per s. h. p. 15 . 1
Comparative Performance of Geared Turbines and Recip-
/ rocatIng Engines*
Steamer 370 ft. X 51 ft. X 27.8 ft., 9,950 tons displacement, on
23.4 ft. mean draft, block coefficient .779. Single screw, driven by
geared turbines. Three boilers, steam 180 lb;, speed 10 knots.
Name, Cairncross; type, cargo steamer.
Sister ship, same as above, but with reciprocating engines,
24X40X66
j= . Name, Cairngowan. Results of a 36-hour trial follow:
Geared
Turbines
Reciprocating
Engines
Mean revs, of screw per minute
H. p. developed
Steam
Temp, of sea water F
Temp, of discharge from condenser. . .
Temp, of hot well
Temp, of feed water
Vacuum in condenser
Coal consumed per 24 hours, tons. . . .
Coal consumed per i. h. p. hour, lb. . .
Coal consumed per sq. ft. of grate, lb.
Water consumed per hour, lb
Water consumed per i. h. p. hour, lb. .
Ash from coal as measured, per cent. .
61.76
1,570 s.h.p.
138 lb.
50°
70°.
79°
203°
28.75 ins.
27.8
1.45
17.9
22,400
12.57
8.50
61.68
1,790 i. h. i
1401b.
50°
95°
104°
221°
26.80 ins.
32.7
1.704
21
27,200
15.18
8.97
See also table of Comparative Performances of Different Systems of Propulsion.
The Fottinger hydraulic transmitter for turbines consists of a
high-speed turbo-centrifugal pump with a water turbine designed
for a low speed. The pump is coupled direct to the steam turbine,
* From Marine Steam Turbines. J. W. M. So them.
Digiti
zed by G00gk
444
MACHINERY
and the water turbine to the propeller shaft, both being in one
casing so designed that frictional and eddy losses are reduced to
a minimum. The transmission efficiency of this transformer is
about 90%, and it has the advantage of being able to employ a
non-reversible turbine.
In Alquist gearing, the gear is built up of a number of plates
machined to a form which gives them the desired degree of lateral
flexibility. Each disk or plate operates independently and is free
to deflect laterally under the side pressure which results from its
diagonal engagement with the pinion. A very small amount of this
lateral deflection is sufficient to afford the desired distribution of the
load, and this amount can be given without approaching dangerous
periodic strains. With gears of the Alquist type very small teeth
can be used without any danger of incurring excessive strains on
the individual teeth. Alquist gears are built by the General Electric
Co., Schenectady, N. Y. Below are tests of two steamers of the
same size and model, both using oil fuel, one being driven by turbines
with Alquist gears and the other by reciprocating engines.
8. 8. La Brea
Alquist
Gear
S. S. Los
Angeles
Reciprocating
Engine
Average speed, knots
Total lbs. of oil used in steaming
Total shaft horse power hours
Lbs. of oil per shaft horse power hour
Rev. of propeller per min
10.9
8,270,000
8,029,000
1.03
90
10.27
7,310,000
5,538,000
1.32
65
Steamers owned by Union Oil Co., Los Angeles, Cal.
Turbo-Electric Propulsion. — Here the turbine drives a generator
which furnishes the current to an electric motor directly connected to
the propeller shaft. Where a wide range of high efficiency is required
for a variety of speeds, electric propulsion has proved satisfactory.
The advantages of this method of propulsion are: the loss due
to the electrical machinery is more than counterbalanced by the
gains secured with high-speed turbines and suitable reduced speeds
of propellers; full effective power is available for going astern;
the turbines always run in one direction, the reversing being done
by changing the direction of the current at the motor; an improved
Digitized
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TURBO-ELECTRIC PROPULSION
445
economy at low speeds is secured, which in war vessels means an
increased radius of action.
In the U. S. collier Jupiter, the generating unit (turbine and
generator) is similar in design and construction to units on shore,
the generator being a three-phase, 2,300-volt, 5,000 kw., furnishing
current to two electric motors one on each shaft, there being two pro-
peller shafts. The motors are of the three-phase induction type
and have 36 poles. Each is installed in a well surrounded by a
coaming, so that it cannot easily be filled by sea water. The wind-
ings are waterproof and not at all sensitive to moisture. When prompt
reversal is required it is desirable to cut in the resistance in the motor
circuit. This is done by levers attached to the motor frames. Rever-
sal under such conditions is accomplished by first opening the field
switch which deenergizes the circuit, then moving the levers which
cut in the resistances, then throwing the reversing switches, and
lastly reestablishing the field circuit. These operations are simple
and can be accomplished in a very few seconds. Locking devices
are provided so that no error can be made.
The following table gives data on three U. S. colliers, viz., Jupiter,
Neptune and Cyclops. The former is electrically driven, the Nep-
tune is driven by geared turbines and the Cyclops by reciprocating
engines.
Cyclops
Jupiter
Neptune
Displacement
20,000
5,600
88 r. p. m.
88
280
2 triple ex-
pansion
engines
14 (estimated)
14.6 knots
20,000
2,000 r. p. m.
110
156
1 turbo-gen-
erator and
2 motors
11.2
20,000
I. h. p. at 14 knots
Engine or turbine speed at 14 knots. . .
Propeller, r. p. m., at 14 knots
Weight driving machinery in tons
Character of driving machinery
Steam consumption in pounds per shaft
horse power per hour
1,250 r. p.m.
135
2 turbines
each with
gearing
Speed maintained on 48-hour trial
13.0 knots
One of the largest electric installations is in the 30,000-ton U. S.
battleship California. Here the current for propelling the battle-
ship is generated by two 18,000 h. p. turbo-generator sets running
at 2,200 r. p. m., furnishing the current to four 7,500 h. p.
induction motors, giving a speed of 22 knots. At 14 knots only
7,000 h. p. is required. Due to the high efficiency of the electric
speed adjustment system employed it is claimed that the steam
ile
446
MACHINERY
Pounds of Steam per Hour per Effective Horse Power
For Direct Drive Turbines, Reciprocating Engines, and Turbo-
Electric Units
Name
How Driven
Speed in Knots
Revolutions
of Pro-
12
19
21
pellers at
21 Knots
U. S. Battleship Florida
U. S. Battleship Utah
U. S. Battleship Delaware . . .
U. S. Battleship California. .
Parsons Turbines
Parsons Turbines
Reciprocating
engines
Turbo-Electric . .
lb.
31.8
28.7
22.
17.3
lb.
24.
20.3
18.7
15.
lb.
23.
21.
21.
16.4
32S
323
122
175
Estimated weight of the propelling machinery of the California without con-
densing auxiliaries is 530 tons. x The contract price with auxiliaries was $431,000.
consumption per horse power hour will be approximately the same
at both speeds. Seventy-five per cent, of the power generated
theoretically by the ship's turbines will be delivered to the genera-
tors, and it is estimated that there will be a loss of only 8% in the
electrical equipment. In addition to the electric power for pro-
pulsion, all of the engine room auxiliaries will be electrically driven
by direct current taken from the small, non-condensing turbo-
generators that supply excitation for the main generators. It is
said that the use of electric drive on the California represents a
saving of about $200,000 in the first cost of the propelling machinery,
and that it offers superior economy in operation, besides reducing
the weight of the propelling machinery and providing full power
for reversing without the addition of astern turbines as is the case
in direct turbine drive.
Efficiency. — Marine steam turbines have an efficiency of 55 to
65% when running at their designed speeds. At other speeds
they are not, as a rule, as efficient as the ordinary reciprocating
engine.
Steam Consumption. — When running at their designed speed
turbines use about 11.85 lb. of steam per shaft horse power, while
reciprocating engines use about 13.65 lb. per i. h. p.
Weights. — With turbines there is a saving of weight chiefly due
to a decrease of 15 to 20% of the boiler capacity required for full
power, owing to the increased economy of turbine machinery. There
is also a saving in weight over those of reciprocating engines and in
the space occupied.
Digiti
zed by G00gk
HORSE POWER
447
Comparative Performances of Different Systems of Pro-
pulsion
Losses Given in
Per cent of Total
Power Developed
Turbine
Connected
Direct to
Propeller
Shafting
Turbine
Drive
Through
Mechanical
Reduction
Gear
Turbine
and
Electric
Trans-
mission
Turbines
and
Hydraulic
Trans-
mission
Fottinger
Type
Combination
—2 Recipro-
cating
Engines
and 1 Low-
Pressure
Turbine
Turbine water rates, lb. per
s. h. p. hour
Mechanical reduction gear
losses
Generator and motor losses. .
Hydraulic transformer losses
Reciprocating engine losses
in combination
Losses in thrust line and pro-
11H to 12
VA%
53%
22 to 23
WA to 11
2%
2H%
65%
17 to 17.7
lOHtoll
Vo'%'
2H%
65%
18.4 to 19.3
lOHtoll
*14%"
2H%
60%
20.8 to 21.9
10H to 11
5.3%
2K2%
60%
19 to 19.9
Propulsive efficiencies
Water rate, lb. per e. h. p.. .
See also the table, Pounds of Steam to Main Engines per Hour per Effective Horse Power.
See also the table, Comparative Performances of Geared Turbines and Reciprocating Engines.
Horse Power. — To calculate the horse power of a turbine an in-
strument called a torsion meter is used, which measures the tor-
sional movement of the propeller shaft.
Let C — pounds per square inch, being the coefficient of rigidity
depending on the material of the shaft
torsion or turning movement on shaft in foot-pounds
angle of . distortion in circular measure between the
two points on the shaft which were originally in the
same straight line parallel to the shaft axis
distance in feet the points are apart
moment of inertia of the shaft cross section in inch
units when calculated from the dimensions of the shaft
by the formula Ja — — (di4— d24) where dx and d2
are the external and internal diameters of the shaft.
rdi*
F
e
L
/a
If the shaft is solid then Jft =
32
N = revolutions of shaft per minute
F = the torsion or turning movement on the shaft in foot-
C X 7a X e
pounds =
144 X L
Hence the shaft horse power (s. h. p.) = 33^55 X 144 * L
Digitized by VjiX3O0^lC
448 MACHINERY
Or the horse power may be calculated if the steam consumption,
heat drop per pound of steam, and turbine efficiency are known —
thus:
calculated shaft horse power =
lbs, of steam per min. X heat drop X 778 X turbine efficiency.
33000
The shaft or brake horse power is usually taken as .9 of the
indicated.
A XS X P
Then s. h. p. —
11.85
To Find the Quantity of Steam used in Pounds per Shaft Horse
Power.
Q = quantity of steam used in pounds per shaft horse
power
A = available heat in B. t. u.'s per pound of steam within
a certain pressure limit Pi — P2
E -* efficiency, which in marine turbines is from 55 to 65%
ft. lbs, per hour 1,980,000
Inen Q A X 77S X E A X 778 X E
Auxiliaries. — These are practically the same as for steam engines
with slight modifications, the chief being in the condenser, as a
greater steam volume issues from a turbine since it operates at a
higher vacuum than a steam engine. The condensers are invari-
ably of the contraflow type, the steam and cooling water circulating
in opposite directions.
A large circulating pump is required, and besides the usual air
pump a dry vacuum pump is often installed. Sometimes, instead
of the dry vacuum pump there is a vacuum augmenter, the chief
purpose of which is to condense the vapor and draw off the air from
the main condenser.
On account of the high speed at which turbines run, an efficient
oiling system is essential. The oil is supplied by forced lubrication
at pressures varying from 15 to 35 lb. to the turbine bearings as
well as to the line shaft bearings.
See section on Auxiliaries.
STEAM PLANT AUXILIARIES
Atmospheric Pressure. — At sea level the pressure of the atmos-
phere varies from 14.5 to 15 lb. per square inch, a fair average being
14.7. Atmospheric pressure is measured by the barometer.
Digitized by vjOOQ I
GAUGE PRESSURE . 449
Gauge Pressure is pressure measured above that of the atmos-
phere. Ordinary steam- gauges indicate pressures above the
atmosphere.
Gross or Absolute Pressure is the gauge pressure plus the at-
mospheric.
Vacuum, see Vacuum and Vacuum Gauge.
Thermodynamics of Condensers. — To condense steam, its latent
heat of evaporation must be transferred to a sufficient weight of
water cold enough to absorb the heat. At 90° F., which corre-
sponds to an absolute pressure of 1.42 ins. of mercury or 28.58 ins.
of .vacuum referred to a 30-in. barometer, steam contains about
1,040 latent heat units (B. t. u.) per pound. If this heat is trans-
ferred to water entering the condenser at 60° and the water thereby
heated to 90°, which is the utmost possible with 90° steam, each
pound of water will absorb 30 B. t. u. Therefore, for each pound
of steam condensed there will be required ~^r- = 34.7 lb. of water
ok)
as the least quantity theoretically possible to condense the steam.
If the water enters at 70°, each pound can only absorb 20 B. t. u.,
1040
and 9 = 52 lb. of water which will be required per pound of
steam. For example, suppose a 10,000 kw. turbine, or engine and
turbine plant uses 15 lb. of steam per kw. hour. If the average
summer temperature of the cooling water is 70° and a steam
temperature of 90° is specified at that season, then — '- ^ —
Ay)
= 7,800,000 lb. of cooling water per hour, theoretically required.
As the cooling water in actual practice never rises fully to the
temperature of the steam, it is necessary to allow for a certain
temperature difference between the outgoing water and the steam.
In most instances condensers are designed for a difference or tem-
perature head of 5° F. or over, depending on the steam and on
the. temperature of the incoming water, but being greater for a
low vacuum (where less water is handled) than for a high, and
greater in winter than in summer.
Owing to condensation in the turbine, due partly to radiation
and partly to expansion, the steam exhausted into the condenser
must contain a certain amount of moisture ranging from 5 to 15%;
that is, the steam gives up part of its latent heat before it reaches
the condenser. It is therefore sufficiently accurate to assume that
the condenser receives 950 B. t. u. per pound of steam used at the
Digitized by VjiOOQ 1C
450 . MACHINERY
throttle when the latter reaches the turbine saturated, and 1,000
B. t. u.'s when it is moderately superheated.
The smallest quantity of water will be required when the cooling
water leaves the condenser at a temperature as close as possible to
that of the entering steam. No condenser produces a perfect vacuum.
A closed vessel exhausted completely of air and partially filled
with water contains water vapor whose pressure will depend on its
temperature. For a temperature of 60° F. it is .52 in. of mercury,
or 29.48 ins. of vacuum referred to a 30-in. barometer; for 80°,
1.029 ins. of mercury and so on. In a steam condenser there is
always present a certain amount of air in addition to the water vapor.
Some of this is carried through with the steam from the feed water;
a large quantity is added by leaks around the piston rod and valve
stem of the low-pressure cylinder of reciprocating engines, or it is
admitted through the shaft stuffing boxes of turbines, also by air
leaks in the joints of the exhaust pipe. In jet condensers a third
source of air, larger than either of the others, is the cooling water
itself, whose absorbed air is set free by the reduced pressure and
increased temperature in the condenser. (Notes from C. H.
Wheeler Mfg. Co., Philadelphia, Pa.)
Condensers convert the exhaust steam from the engine and
turbine into water. There are three types, viz., jet, surface, and
keel. The former consists of a cone-shaped chamber in which
the steam and cold condensing water are mingled, the steam giving
up its heat to the relatively cool water, and being reduced to the
liquid state again. The condensing water enters at the top of the
chamber and falls upon a plate pierced with a large number of
small holes and known as the scattering plate. The condensed
steam and condensing water fall together to the bottom of the
condenser and are pumped by the boiler feed pump to the boilers.
Should there be a superfluous amount this is discharged overboard
by another pump. It is evident that jet condensers can be installed
only in vessels running on freshi water. See also Jet Condensers.
Surface Condensers are cylindrical or rectangular in shape.
When the latter they may form part of the frame supporting the
engine cylinders. In either case they contatin a large number of
small brass tubes, fastened at each end to tube sheets. The con-
densing water is driven by a circulating pump (generally a cen-
trifugal one) through the tubes, the water being drawn from the sea.
The steam entering the condenser at the top comes in contact
with baffles or diaphragm plates preventing it from rushing through
Digitized by VjOOQ 1C
FEED WATER HEATER
451
Digiti
zed by G00gk
452
MACHINERY
the condenser to the bottom and causing it to be broken up and to
pass around the tubes through which the cold water is flowing,
thus condensing the steam into water which is pumped to the hot
»*well by an air pump. The coldest water usually enters at the bot-
tom, meeting the steam at the lowest temperature, and the warmest
water at the top comes in contact with the tubes which are sur-
rounded by the hottest steam. The cooling water often flows
through the condenser two or three times, and travels in an oppo-
site direction to the steam.
Sizes op Surface Condensers, Air and Circulating Pumps
Size of
Engine
17 X 27 X 43
24
Twin
17 X 27 X 43
24
25 X 41 X 68
4?
24 X 40 X 63
49>4
20 X 33 X 54
40
29 X 49 X 84
54
Triple screw
turbine, to-
tal s.h.p.
25,000
Cooling
Surface in
Condenser
in Sq. Ft.
1,350
2 cond. total
cooling sur-
face, 2,750
4,500
3,000
1,563
6,800
2 cond. each
13,046
Air Pump
Independent — 2 single acting cylinders
— steam 1Yi ins. dm., 2 air cylinders,
16^ ins. dia. by 10-in. stroke.
One air pump for the 2 condensers,
12 in. dia. steam cylinder with 2 20-in.
buckets with stroke of 12 ins.
Vertical duplex Blake, 10 X 22 X 25
23% in. dia. X 23% in. stroke.
20 ins. dia. X 14-in. stroke
0 ins. dia. X 24-in. stroke
One pump for each cond., twin beam,
vert., single acting Blake — air cylin-
ders, 32 ins. dia., steam 14 ins. dia. by
21 ins. stroke.
Circulating Pump
Centrifugal, 8-in. sue,
8-in. dis. engine, 7X7
2 circulating pumps,
one for each cond., cen-
trifugal, 8-in. sue, 8-in.
dis., engine 7X7
Cent., 10-in. sue., 10-in.
dis, engine 12 X 10
14-in. dia. X 23%-in.
stroke.
Cent., 9-in. sue., 8-in.
dis., engine 7X7
Cent., 12-in. sue, 12-in.
dis., engine 9 X 10
Cent, pump, 26-m. sue,
26-in. dis.
Structural Features of Surface Condensers. — In modern ships
with triple expansion engines the area of the cooling surface in a
condenser is from 1 to 1.25 sq. ft. per i. h. p. In warships, 1 sq. ft.
per i. h. p. has been found sufficient. With steam turbines where
a higher vacuum can be more advantageously utilized than with
reciprocating engines, the cooling area may be 1.2 sq. ft. per shaft
nvJ^v^
OPERATING 463
horse power for turbine warships. In torpedo boats the area is
sometimes as low as .75 sq. ft.
The shells are made of cast iron, sheet brass, or steel plates.
The tubes are of thin brass, usually J^ to jfr£ inch outside diameter.
They are fastened to tube sheets by ferrules which by screwing
down compress a packing, thereby making a watertight joint.
Surface condensers are provided with the following fittings and
connections:'
Main air pump suction
Suction from some fresh water pump, as hot well pump, for keep-
ing condenser clear when main engines are stopped
Drain cocks for both salt and fresh water ends
Air cocks to allow any accumulation of air to escape
A boiling out connection so steam can be admitted to boil out
the condenser
A connection for admitting soda in solution
A vacuum gauge and a water gauge
Zincs are fitted in the salt water side and should have a good
metallic contact with the heads
Hand holes. Connection for making up feed from fresh water tank.
Operating.* — To remove grease and dirt which accumulates on
the outside of the tubes, the condenser should be boiled out. This
is done by admitting potash or soda through the soda cock, the
soda being first dissolved in water. Live steam is then turned
into the condenser through the boiling out eonnection. The mix-
ture of soda and steam dissolves the grease, forming a soapy sub-
stance which can be drained off. Additional Water is introduced
to wash away the accumulation and remove the extra soda.
The vacuum may be lost through the following causes:
Head or bucket valves of air pump broken;
Injection pipe stopped up;
Division plate in condenser door carried away;
Leaky low pressure gland;
Leaks in shell and joints.
To find the probable cause of the loss of vacuum feel both ends
of the condenser. If both are cold, the air pump valves are broken
or there is a leaky low-pressure gland. If both are warm, either
a broken circulating pump valve or a choked injection valve is
the cause. If one end is cold and the other warm, the division
plate in the condenser door is most likely carried away.
* Abstracts from Care of Naval Machinery. H. Dinger.
16
Digitized
by Google
454
MACHINERY
Figure 76. — Piping of Condenser and Feed Tank — with a Radojet air pump *j
installed.
To locate quickly a leak in a condenser, take off the handhole
plates at one end and start up the air pump. Hold a lighted candle
around the tube ends. Where the flame is drawn in there is a
leak, and such tubes should have their glands set up; or if it is the
tube that leaks, it should be plugged by screwing in a metal plug
or driving in a wooden one.
Vacuum and Vacuum Gauge. — A vacuum gauge or Bourdon's
tube is graduated in inches of mercury and indicates the difference
between the absolute pressure on the inside of the tube and the
atmosphere. As the pressure in the condenser is independent of the
atmospheric, the vacuum registered will vary with the height of the
barometer. Suppose the absolute pressure in the condenser cor-
responds to 3 ins. of mercury. If the barometer is at 30 ins., the
vacuum gauge would indicate 30 — 3 = 27 ins., or if the barometer
was at 28 ins., the gauge would indicate 28 — 3 = 25 ins.
y Google
TO FIND THE VACUUM
455
In reciprocating engines only a slight gain is obtained thermo-
dynamically in a vacuum above 26 ins., owing to increased cylinder
condensation caused by the difference in the inlet and outlet tem-
peratures of the steam. If the condenser is tight and the air pump
in good condition, 26 ins. should be maintained even in hot weather.
In turbines 28 to 29 ins. are obtainable, and with a Parsons
vacuum augmenter installed the vacuum is one inch less than the
barometer reading.
To Find the Vacuum under Given Working Conditions. — If the
temperature of the condenser is 101° F., and the barometer stands
at 30 ins., equivalent to a pressure of 14.7 lb. per square inch, the
vapor pressure corresponding to 101° (see table below) is .980 lb.
per square inch; thus the greatest vacuum possible would be 14.7
— .980 = 13.72 lb. per square inch below the atmosphere, equiva-
lent to 27.5 ins. on the vacuum gauge.
Vacuum
Absolute
Absolute'
Tempera-
Sensible
Total
Meas-
Pressure
Pressure
ture of
Latent
Heat of
Heat of
ured in
in
in Pounds
Boiling
Heat of
Evaporation
from
Evapora-
Inches
Inches
per
Point
Evaporation
tion from
of
of
Square
in
in
32° F. in
32° F. in
Mercury
Mercury
Inch
Degrees F.
B. t. u.
B. t. u.
B.t.u.
29^
a
.245
59.1
1072.8
27.1
1100.0
29
i
.490
79.3
1058.8
47.3
1106.1
2sy2
IH
.735
92.0
1049.9
60.1
1110.0
28
2
.980
101.4
1044.4
69.5
1112.8
27
3
1.470
115.3
1033.7
83.4
1117.1
26
4
1.96
125.6
1026.5
93.8
1120.3
25
5
2.45
134.0
1020.6
102.2
1122.8
24
6
2.94
141.0
1015.7
109.3
1125.0
23
7
3.43
147.0
1011.5
115.3
1126.8
22
8
3.92
152.3
1007.8
120.2
1128.4
21
9
4.41
157.0
1004.5
125.4
1129.8
20
10
4.90
161.5
1001.3
129.9
1131.2
19
11
5.39
165.6
998.4
134.1
1132.4
18
12
5.88
169.2
995.9
137.7
1133.5
17
13
6.37
172.8
993.4
140.3
1134.6
16
14
6.86
176.0
991.1
144.5
1135.6
15
15
7.35
179.1
988.8
147.7
1136.5
14
16
7.84
182.0
986.9
150.6
1137.4
12
18
8.82
187.4
983.1
156.0
1139.1
10
20
9.80
192.3
979.6
161.0
1140.6
5
25
12.25
203.0
972.1
171.8
1143.9
0
30
14.70
212.0
965.7
180.9
1146.6
14.7 lb. — atmospheric pressure — 30 inches of mercury.
Table from Marine Steam Engine. R. Sennett and H. J. Oram.
Digitized by VjiOOQIC
456
MACHINERY
Vacuum and Corresponding Steam Temperature in Condenser
Temperature
Temperature
Vacuum
inches
(Fahrenheit)
degrees
Vacuum
inches
(Fahrenheit)
degrees
20
161.5
26
125.4
21
157.0
26^
120.4
22
152.2
27
115.1
23
146.8
27H
108.6
24
140.8
28
101.2
25
133.7
28}£
91.8
29
79.1
Miscellaneous Notes. — The pressure in the condenser can be
determined from the hot well temperature by noting the hot well
temperature and looking in the table of saturated steam for the
corresponding pressure.
Example. The temperature of the water in the hot well is 141°. Find the pres-
sure in the condenser.
On looking up in the table of Saturated Steam, the pressure at this tempera-
ture is 3 lb. absolute, which is then the pressure in the condenser.
The actual pressure on the low-pressure cylinder is from 1 to
2 lb. in excess of this, as a difference of pressure must exist for the
steam to flow. Thus it is impossible to have a high vacuum and hot
well temperature at the same time, as the two vary in inverse ratio.
With a high temperature of the hot well water the vapor corre-
sponding to the temperature is also high with a proportionally
reduced vacuum in the condenser.
Under ordinary conditions and with 25 to 26 ins. of vacuum,
the temperature of the condenser discharge should be about 110° F.
A lower temperature would indicate that an unnecessary amount
of water is being pumped. See table under Circulating Pump.
It is estimated that 20 volumes of water absorb one volume
of air; hence if means were not taken tp remove this air from the
condenser, it would fill it and destroy the vacuum. For this reason
dry vacuum pumps are installed.
One square foot of cooling surface in a surface condenser is allowed
to condense 10 lb. of steam with the temperature of the circulating
water at 70°, based on obtaining a vacuum of 25 ins.
Jet Condensers. — The capacity of a jet condenser should not
be less than one-fourth of the cylinder or cylinders exhausting into
it, one-third the capacity being generally sufficient. The objection
Digitized by vjOOQ 1C
COOLING WATER REQUIRED 457
to a large condenser, besides its cost and weight, is that a longer
time is necessary to get a good vacuum. See Condensers.
With a jet condenser a vacuum of 24 ins. is considered fairly
good, and 25 good. The temperature corresponding to 24 ins.
or 3 lb. absolute pressure is 140°. In actual practice the tem-
perature in the hot well varies from 110° to 120° and sometimes
130° is maintained by a careful engineer.
To Calculate the Quantity of Cooling Water Required for Either
a Surface or a Jet Condenser.*
Let T\ - temperature of steam entering the condenser
L — the latent heat of the steam
To — the temperature of the circulating water
Q = the quantity of circulating water
Ti = temperature of the water leaving the condenser
Tz = temperature of the feed water
The heat to be absorbed by the cooling water is (T\ + L) — Tz
and is equal to 966 + .7 X 212° + .3 (T2 - T0) or Q (T2 - T0) w
Hence Q (T2 - TQ) = (Ty+ L) - Tz
_ 1114 + .3 Tj - Tz
V T2 - To
Example. To find the amount of circulating water required by an engine with
an exhaust at 8 lb. absolute pressure, the temperature of the sea being 60°. Also
find the amount of water required when the sea temperature is 75°. The tem-
perature of the water at the discharge is 100°, and of the feed 120°. The tem-
perature corresponding to 8 lb. is 183°.
At 60°
1114 4. 9 y 183° 120°
q = i'oq*-- eiy* — = 2622; that is' the water re<iuired is 26 22
times the weight of the steam.
At 75°
_ 1114 + .3 X 183° - 120°
Q 100° - 75° 4195 time8- -
The quantity of sea water will depend on its initial temperature,
which in actual practice varies from 40° in the winter of temperate
zones to 80° in the West Indies and tropical seas. In the latter
case a pound of water requires only 20 thermal units to raise it
to 100°, while 60° are required in the former. Thus the quantity of
circulating water required in the tropics is three times that required
in the North Atlantic in the spring of the year.
A rough approximation is 27 lb. of circulating water for every
* From Practical Marine Engineering.
Digiti
zed by G00gk
$T£AM
^(jcr/ort
D/SC#AfiK?C
Figure 77. — Air Pump (Worthington Pump Co., New York).
458
OUTBOARD CONDENSERS 469
pound of steam condensed. About 25 gallons of water are required
to condense the steam represented by one gallon of water evap-
orated, or one to one and a half gallons per minute per one h. p.
Jet condensers do not require so much water for condensing as
surface condensers.
Keel or Outboard Condensers consist of pipes on the outside
of the hull near the keel, into which the engine exhausts. They
are often installed in launches, tugs, lighters, and small passenger
steamers, and are of iron, brass, or copper pipe with an air pump
operated by the engine — or, instead, the air pump may be inde-
pendently steam driven. Neither copper nor brass should be used
for keel condensers on vessels running in salt water, unless the
stern bearing, propeller wheel, and tail shaft are of bronze. Neither
should iron nor steel pipe be used if the vessel is coppered or has a
bronze outboard bearing.
Air Pump. — The function of an air pump is to draw out the air
and water from a condenser and by the vacuum formed reduce the
back pressure on the low-pressure piston. The air pump is often
driven direct from the main engine, or it may be separate, having
its own steam cylinder.
There are two types, viz., single- and double-acting. The former
is vertical and is usually selected. In the single-acting there is
a reciprocating bucket or piston with orifices covered by non-return
valves which move in a cylindrical barrel at each end of which
are covers with orifices and non-return valves. These three sets
of valves lift vertically and allow the passage of water or air in
only one direction. The suction pipe of the air pump communi-
cates with the bottom of the condenser, the pump being placed
lower than the condenser to get the most satisfactory results. The
valves at the lower end are called foot or suction valves, those in
the moving bucket, bucket valves, while those in the top are the
head or discharge valves.
The stroke of a vertical air pump when driven from the main
engine is \i to % that of the engine, but its speed should not exceed
300 ft. per minute, and for continuous running should be about
275 ft.
Edward's air pump is a single acting vertical pump with valves
only at the top to check the discharged water and air from returning
to the pump on the down stroke. This pump is very simple and
gives a good vacuum. See Fig. 78.
Double-acting air pumps are of the horizontal type and have an
*
460
MACHINERY
efficiency ranging from 30 to 50%, a fair average being about 35.
Single-acting, 40 to 60% with an average of 50.
The capacity of an air pump is generally taken as ^ to ^ of the
capacity of the low-pressure cylinder. One authority, Mr. Le
Blanc, states that for turbines with a 29-inch vacuum the air pump
must handle 21 times the volume of feed water, and for a recipro-
cating engine with a 26-inch vacuum the pump must handle 12 times
the volume of water.
"S^^
EDWARDS AIR PUMP
£8 NOVY EXIEN8JVELY U8EJ) ON MERCHANT 8HJP^
Figure 78.
Independent from main engine, vertical twin-cylinder air pumps
for jet and surface condensers, having 2 steam and 2 water cylinders,
jvJ^v^
AIR CIRCULATING PUMPS
461
are given in the following table. The pumps are single-acting,
and the capacities given are the capacities per revolution for each
side; for a complete revolution the capacity is twice that per side.
The pumps can be run at 100 ft. per minute, but for constant a
speed of 75 ft. or less is recommended.
■•^
r
Steam
Cylinders,
Inches
Air
Cylinders,
Inches
Stroke,
Inches
Gallons
per Stroke
Steam
Pipe,
Inches
Exhaust
Pipe,
Inches
8
16
12
10.44
m
2y2
10
16
12
10.44
VA
2H
• 12
16
12
10.44
1%
3
8
18
12
13.22
m
2H
10
18
12
13.22
m
2*A
12
18
12
13.22
m
3
10
20
12
16.32
im
2y2
12
20
12
16.32
2lA
3
10
22
15
24.68
iH
2M
12
22
15
24.68
2H
3
14
22
15
24.68
2i4
3
12
24
18
35.25
•2H
3
14
24
18
35.25
2M
3
12
30
18
55.08
2H
3
14
30
18
55.08
2H
3
16
30
18
55.08
3
3M
14
36
18
79.32
2^
3
16
36
18
79.32
3
3H
18
36
18
79.32
Wi
3H
16
38
20
98.20
3
VA
18
38
20
98.20
zy2
VA
20
38
20
98.20
W2
VA
18
40
24
130.58
W2
3A
20
40
24
130.58
W2 .
m
24
40
24
130.58
4
4
24
48
24
188.04
4
4
30
48
24
188.04
VA
4^
30
58
24
274.00
4^
4^
Dean Bros., Indianapolis, Ind.
See table of Sizes of Condensers, Air and Circulating Pumps.
A new type of air pump (trade name Radojet, C. H. Wheeler
Mfg. Co., Phila., Pa.) is shown in Fig. 76. This pump is a substitute
for any air pump working on the dry air principle. It has no
piston nor valves, and is operated by live steam jets which by
passing through nozzles of patented design obtain a high velocity
that entrain the air and non-condensable gases from the condenser.
Digitized
by Google
462 MACHINERY
The ordinary reciprocating air pump may be replaced by a Radojet
removing the air, while a small, direct acting, hot well pump removes
the condensed steam from the condenser. The arrangement is practi-
cally the same for either reciprocating engines or turbines, only in
the latter a direct acting duplex reciprocating pump is employed
for removing the condensed steam from the condenser.
Circulating Pump. — This forces the cooling water through the
condenser tubes, and is either of the reciprocating or centrifugal
type; if the latter, is driven by a steam engine running at about
200 revs, per minute or it may be driven by a turbine at a higher
speed. The water should be pumped through the tubes at a velocity
of about 115 ft. per minute, when the sea water is at 60°, and 170
ft. when at 75°, the speed of the pump being so regulated that the
temperature of the discharge water is about 20° below the tem-
perature corresponding to the vacuum that is to be maintained.
Vacuum,
Inches
Temperature of Discharge Water Corresponding
to Vacuum, Degrees
28
26
24
22
20
100
125
140
152
161
If the circulating pump breaks down, connect up the donkey
pump to the condenser for circulating the water, but if this cannot
be done, or if no other pump can be connected up, then the engines
must be run jet condensing if the steamer runs in fresh water, or
non-condensing if in salt water. To do this draw a number of the
condenser tubes, and open up the air pump discharge valve. To find
thenumberof tubes todraw, use theformula ConS^tXlh^S
= number of tubes.
See section on Pumps; also table of Sizes of Condensers, Air
and Circulating Pumps.
Feed and Filter Tank (Hot Well).— The air pump discharges
the condensed water from the condenser into a combined feed and
filter tank. In large vessels this tank has sufficient capacity for
10 to 15 minutes running at full boiler power. The tank is divided
into several compartments. See Fig 76.
Digitized
by Google
FILTERING MATERIALS
463
As to filtering materials, coke in bags of burlap or heavy toweling
is fairly satisfactory. When the coke is to be renewed the bags
are washed with soda and refilled with fresh coke.
Zincs are suspended in the feed tanks to absorb oxygen.
Steam Traps. — As steam condenses in the pipes through which
it passes it is necessary to drain the condensed water off, and this
is accomplished by pipes leading to traps where the water is col-
lected and from which the water goes to the filter tank for use over
again in the boiler.
The best way to specify the size of a trap is to specify the size
of the orifice in the valve and the maximum pressure the trap
will work under. The orifice in the valve is always the capacity
of the trap and no more condensation can pass through the trap
than will pass through the orifice, regardless of the size of the pipe
connections. Hence the only accurate way of deciding on a steam
trap for any service is to know its discharge capacity in pounds
or gallons per hour.
Under ordinary conditions 9 ounces of condensation per linear
foot of one-inch pipe per hour are allowed. To compute the equiv-
alent in one-inch pipe of a given quantity of pipe of other sizes,
multiply the number of linear feet of a certain size by the figure
underneath that size, as in the table below.
Size of Pipe, Ins.
\k
m
2
2H
3
3H
4
4H
5
6
7
8
0
10
12
Multipliers.....
1.26
1.44
1.81
2.19
2.66
3.04
3.42
3.80
4.23
5.43
5.80
6.55
7.34
8.18
9.72
To find the rated allowance of condensation in ounces per linear
foot per hour of any steam trap, take the rated discharge capacity
in pounds per hour, and compute same in ounces; then divide
by the number of rated linear feet and the result is the allowance
of condensation per linear feet per hour.
The rating in feet of one-inch pipe of a steam trap, based on
a fixed amount of condensation per foot per hour, will be materially
reduced when the condensation is severe, say 25 ounces of conden-
sation per foot per hour.
To determine the number of linear feet a trap will take care of,
compute the capacity of condensation in pounds per hour and then
in ounces; next decide on the allowance of condensation per foot
per hour and divide it into the capacity. The quotient will be the
Digitized by vjOOQ 1C
464
MACHINERY
number of linear feet. Thus suppose a trap is rated at 4,380 lb.
per hour and the allowance per foot of one-inch pipe is 25 lb.; then
4,380 lb. per hour (capacity)
16
70,080 oz. per hour,
70,080
25
= 2,803 linear feet of 1-inch pipe
Figure 79.— Feed Water Filter.
Feed Water Filter. — Referring to the filter in Fig. 79 (Ross Valve
Co., Troy, N. Y.) the water enters the right hand pipe at the top
and flows into the chamber below. The central portion of the
chamber is occupied by the filter. The filtering material is known
as linen terry or Turkish toweling. The toweling is over a bronze
nvJ^v^
FEED WATER HEATERS; [465
circular frame, the filtering surface being from 150 to 1000 times
the area of the feed pipe according to the service required. When
a feed water heater is used, water should first pass through the
filter.
Feed Water Heaters. — These are either open (jet) or closed
(surface). Open heaters consist of a closed chamber into which
the feed water is delivered by a pump. In this chamber it overflows
a series of trays and condenses the exhaust steam in the same
manner as a jet condenser. The resulting hot water is pumped by
the boiler feed pump to the boiler. With this type the temperature
of the feed water cannot be above about 180°, as a higher tempera-
ture would cause vapor to- form and the feed pump would not
have a proper suction.
The closed type of heater operates like a surface condenser.
It consists of a cast iron chamber containing brass or copper tubes
through which the water from the hot well is forced by the boiler
feed pump on its way to the boiler. The space around the tubes
is filled with exhaust steam (from the main units or the auxiliaries),
the water entering the tubes either cold or at hot well temperature.
When there is an excess of exhaust steam, the water goes to the
boiler within a few degrees of the exhaust steam temperature.
When the exhaust steam supply is limited, practically all is condensed
in the heater, and its latent heat transferred to the water, thereby
determining the resultant temperature of the water. Two systems
are in use, one where the heater is on the suction side of the feed
pump and the other where it is on the discharge side. With the
heater on the suction side of the pump a hot well pump is needed.
To get 220° temperature a pressure of around 5 lb. above the at-
mosphere is necessary. ^Ordinarily a saving of one per cent, is made
by each increase of 11° F. in the temperature of the feed water,
which is about .09 per cent, per degree. That is, an approximate
rise of 10° in the temperature of the feed water gives a saving of
1 per cent, in the amount of coal used. An efficient heater will
give the feed water a temperature within 10° of the temperature of
the steam.
Example. The temperature of the feed water entering a heater is 70° F., and
on leaving 81°, steam 100 lb. at the gauge, containing 1,189 B. t. u. per pound.
Find the saving in per cent if the temperature is raised 11°.
Let H = total heat in one pound of steam at the boiler pressure
Hv — total heat in one pound of feed water before entering the heater
Ht — total heat in one pound of feed water after leaving the heater
ioogle
Figure 80.— Feed Water Heater.
466
Digitized
by Google
EVAPORATORS
467
\
Then per cent saved = jy _ i/
Temperature of feed water entering heater = 70° and oontains 70° — 32° —
38 B. t. u. per lb.
Temperature of feed water leaving heater » 81° and oontains 81° — 32° =
49 B. t. u. per lb.
Saving in raising temperature 11° —
49-38
Ht -Hi ______
H- Hi 1,189 -J
- .96%
Fig. 80 is of a feed water heater built by Schutte & Koerting,
Phila., Pa., of concentric spiral corrugated tubes. This construction
besides agitating the water and so preventing the formation of cold
cores, keeps the water in a thin film between two heated copper
surfaces. This gives an exceedingly high rate of heat transmission,
and yet at the same time a light and efficient heater. The heater
may be arranged either vertical or horizontal..
Percentage Saving in Fuel by Heating Feed Water With
Exhaust Steam
100 lb. Boiler Pressure
Initial
Temp.
Final Temperature of Feed Water
Initial
Temp.
of Feed
Water
120°
130°
140°
150°
160°
170°
180°
190°
200°
210°
220°
230°
of Feed
Water
°F.
40°
50*
60*
70*
80°
90°
100°
110°
120°
130°
%
6. 8
5.95
5. 1
4.25
3. 4
2.55
1. 7
0.85
%
7.65
6.85
6.04
5.23
4.39
3.54
2.68
1. 8
0.91
%
8.72
7.92
7.12
6.27
5.43
4.57
3.68
2.78
1.88
0.95
%
9.35
8.57
7.67
6.97
6.15
5.32
4.47
3.61
2.73
1.84
0.92
%
10.45
9.70
8.90
8.07
7.24
6.40
5.53
4.65
3.75
2.84
1.90
0.97
%
11.05
11.28
9.50
8.72
7.91
7.09
6.26
5.41
4.55
3.68
2.98
1.97
%
12.20
11.45
10.70
9.87
9.05
8.22
7.38
6.52
5.63
4.74
3.83
2.90
%
13.07
12.32
11.60
10.75
9.95
9.13
8.30
7.43
6.58
6.68
4.80
3.85
%
13.95
13.20
12.45
11.65
10.85
10.05
9.22
8.38
7.50
6.63
5.75
4.83
%
14.80
14.10
13.35
12.55
11.75
10.95
10.15
9.30
8.45
7.60
6.70
5.80
%
15.70
15.00
14.25
13.45
12.70
11.90
11.05
10.25
9.40
8.55
7.65
6.75
%
16.55
15.85
15.15
14.35
13.60
12.80
12.00
11.15
10.30
9.45
8.60
7.72
°F.
40°
50°
60°
70°
80°
90°
100°
110°
120°
130°
140°
140°
150°
150°
Evaporators are for treating salt water so that it can be used
in the boilers. AH types work on the same principle; that is, the
salt water is heated by steam from the boilers. The boiler steam to
the coils of an evaporator is merely a medium for carrying heat to
the apparatus, and is returned to the boiler as hot feed after it is
condensed in the coils. The quantity of steam or coal required to
produce a ton of distilled water depends on the temperature of the
le
468
MACHINERY
evaporator feed and the pressure of the steam in the coils. Neglect-
ing radiation, there is always a loss in heating an evaporator, due
to blowing down, but under ordinary working conditions this loss is
only about 5%.
The following table shows the pounds of boiler steam required
to produce one pound of pure water at various pressures and feed
temperatures, working single effect and under normal conditions,
and neglecting radiation loss. The figures do not include steam
used by feed pump or circulating pump.
Boiler Steam Pressure
Temperature of Feed Water
to Coils
50°
75°
100°
125°
150°
175°
200°
225°
75 lb
1.30
1.31
1.32
1.34
1.36
1.38
1.41
1.43
1.26
1.27
1.29
1.31
1.33
1.35
1.37
1.39
1.22
1.23
1.25
1.27
1.29
1.31
1.33
1.35
1.17
1.19
1.21
1.23
1.25
1.26
1.28
1.30
1.14
1.15
1.17
1.19
1.20
1.22
1.24
1.26
1.10
1.11
1.13
1.14
1.16
1.18
1.20
1.22
1.06
1.07
1.09
1.10
1.12
1.14
1.15
1.17
1.03
100 lb
1.04
125 lb
1.05
150 lb
1.06
175 lb
1.08
200 lb
1.10
225 lb
1.11
250 lb
1.13
Figure 81.— Piping of Distiller and Evaporator (M. T. Davidson 6 Co., New York).
Digitized by VJiOOQLC
DIMENSIONS OF EVAPORATORS
469
Dimensions of
Evaporators*
Diameter of Connections
Size
Diameter
of Shell
Height
of Shell
No.
Steam
Vapor
Feed
Blow
Drain
Inlet
Outlet
Inlet
Off
from Coils
Inches
Ft. In.
Inches
Inches
Inches
Inches
Inches
1
10
5 0
lA
1
• A
X
A
2
13
5 0
%
IX
A
H
A
3
15
5 3
l
IX
H
%
H
4
18
5 6
l
IX
*A
H
H
5
24
6 0
l
134
1
l
M
6
30
6 6
IK
2
IK
l
l
7
30
6 6
IX
2
1M
l
1
8
36
7 0
VA
2V2
\A
IK
1
9
♦ 36
7 0
iy2
2V2
\A
W
1
11
40
7 6
2
3
2
IX
l
12
40
7 6
2
zy2
2
iVi
l
13
45
7 9
2
*y2
2
w*
lA
14
50
8 0
2V2
4
2A
llA
lA
16
60
8 0
2^
4
2H
1A
\A
17
60
8 3
2Y2
4
2A
lA
\A
Capacities op Evaporators
Tons per
24 Hours
Gallons per 24 Hours
Size
Diameter
of Shell
Weight
No.
«,
Minimum
Maximum
Minimum
Maximum
Inches
Pounds
1
10
.83
200
....
200
2
13
1.20
300
400
3
15
2.08
2.50
500
600
548
4
18
3.66
4.17
880
1,000
630
5
24
5.00
5.62
1,200
1,350
960
6
30
7.08
8.33
1,700
2,000
1,295
7
30
8.54
9.58
2,050
2,300
1,450
8
36
10.42
12.08
2,500
2,900
1,697
9
36
13.33
15.00
3,200
3,600
1,830
11
40
14.58
16.67
3,500
4,000
2,286
12
40
18.75
20.83
4,500
5,000
2,600
13
45
22.66
25.62
5,440
6,150
2,740
14
50
27.92
31.67
6,700
7,600
3,558
16
60
33.33
37.50
8,000
9,000
5,600
17
60
45.00
50.00
10,840
12,000
5,845
Minimum capacities represent quantity of pure drinking water;
maximum capacities represent quantity of make-up boiler feed
water. oigiti^dby >Ogr
* Reilly multicoil evaporators, Griscom-Russell Co.
470 MACHINERY
As to the size to be installed, a fairly good rule is to allow one
ton of water per day per 100 i. h. p. of the engine. The Reilly
multlcoil evaporators (Griscom-Russell Co., New York) have a
rated capacity based on a steam pressure of 75 lb. in the coils with
a feed temperature of 75° and a pressure of 15 lb. maintained in
the vapor space in the shell. Increase of steam pressure in the
coils materially increases the capacity with slightly diminished
efficiency.
Feed water may be made by a single effect evaporator (that is,
using only one evaporator), for only a nominal consumption of
coal, preferably the drain from the coils is led to the hot well and
the heat of the drain is saved. If the vapor from the shell is also
led to the hot well and there condensed, this heat is also saved,
and practically the only loss during the operation is due to blowing
down and radiation.
Another method that is not so economical is leading the vapor
to the low-pressure casing of the main engine. The least econom-
ical method is to lead the vapor direct into the main engine condenser.
The figures given below show the efficiency of the three methods.
To produce 2,000 lb. of feed water witfci good coal, neglecting radi-
ation, would require:
Vapor leading to hot well or feed water heater 15 lb. of coal
Vapor leading to low-pressure cylinder 175 lb. of coal
Vapor leading to main engine condenser 235 lb. of coal
Sometimes evaporators are used in multiple effect as by installing
three, viz., high-pressure, intermediate, and low.
PUMPS
There are two types, reciprocating and centrifugal, each being
particularly adapted for certain conditions; the former where the
water has to be lifted by suction say a distance of 20 ft. and the
latter for delivering a large volume under a small head as in sup-
plying the cooling water to a marine surface condenser.
In reciprocating pumps the pressure or head depends directly
on the steam pressure in the cylinder (omitting loss of head by
friction and turns), and in centrifugal the theoretical head against
which a pump can deliver is represented by the pressure in the water
leaving the impeller plus the pressure due to converting the velocity
energy of the water leaving the impeller into pressure.
A pump should be located as near the water to be pumped as
possible, and when pumping from the sea it should be placed below
Digitized by VjOOQ IC
SUCTION HEAD 471
the water line so that the water may flow to it by gravity. All
suction pipes from the sea must be fitted with a cock or valve and
a strainer placed over the outboard opening. The cock or valve
should be near the hull or attached to it, so that the suction pipe
to the pump can be removed for renewal or repairs. In pipes dis-
charging overboard, unless the pump is above the water line, check
valves are installed in the pipes.
When pumps are some distance above the water line, a foot valve
is frequently placed in the suction. This is a check valve opening
toward the pump and is put next the cock or valve attacheji to
the hull. Its purpose is to prevent the emptying of the suction
pipe while the pump is at rest. When pumps are below the water
line a foot valve is not required.
If drawing or forcing water long distances or at high speeds, the
diameters of the pipes should be greater than the openings on the
pump.
Suction Head is the distance from the surface of the suction
water to the center of the pump plus frictional resistance through
the piping and fittings. The suction head should not exceed 25 ft.
Discharge Head is the distance above the pump shaft up to
the point of discharge plus frictional resistance in the pipe. To
find the discharge head in feet, multiply the pressure by 2.31.
„T , , Gallons per minute X head in feet
Water horse power = — — ^r^
««. . Water horse power _,-. . r ,.
Efficiency = = — r — r - . Efficiency of reciprocating
pumps varies from 60 to 70% and of centrifugal pumps 30 to 50.
For estimating size of boiler feed pumps, the formula Gallons per
Boiler horse power ... ,
minute = ig n could be used.
lo.o
Reciprocating Pumps. — Vertical reciprocating pumps are prefer-
able to horizontal, for marine purposes, on account of the small
horizontal space available on a vessel. The vertical type is exten-
sively used for boiler feed, drainage systems, fire purposes, etc.
Duplex pumps are practically two single pumps placed side by side,
the valve movement of one pump being actuated by connections
with the piston rod of the other.
The height to which a pump will lift water depends on atmos-
pheric pressure. One pound per square inch corresponds to a head
of water of 2.309 ft. Therefore, to find the lift of a pump, multiply
Digitized by VjOOQ IC
472 MACHINERY
the pressure per square inch, obtained from the barometer reading,
by 2.309.
Example. At sea level the barometer stands, say, at 30 ins., and the correspond-
ing pressure is 14.72 lb. Thus the theoretical lift of a pump would be 14.72 X
2.309 ft. = 34 ft. But in actual practice it requires a good pump to draw to a
height of 28 ft.
To find the discharge of a pump in gallons per minute,
Let T = piston travel in feet per minute
d = diameter of cylinder in inches
G = number of U. S. gallons discharged per minute
Then G = .03264 X T X &
To find the horse power necessary to elevate water to a given
height, multiply the total weight of the water in pounds delivered
per minute by the distance in feet between the suction and discharge
water level and divide the product by 33,000. To this quotient 25%
should be added for water friction, and 25% for loss in steam^cylinder.
The area of the steam piston multiplied by the. steam pressure
gives the total amount of pressure that can be exerted. The area
of the water piston multiplied by the pressure of water per square
inch gives the resistance. There must be a margin between the
power and the resistance to move the pistons at the required speed,
say from 20 to 40% according to the speed and other conditions.
The duty of a pump is the number of foot-pounds of work actually
done by 100 lb. of coal burned.
rr.u j A oop ro Gallons per min. X lift in ft.
Thus duty = 835.53 w . , - . y . , -r-. -3-
Weight of coal burned m pounds
To find the quantity of water elevated in one minute, running
at a piston speed of 100 ft. (a fair average) per minute, square
the diameter of the water cylinder in inches and multiply by 4.
Suppose the capacity of a 5-inch cylinder is desired; the square
of the diameter is 25, which, multiplied by 4, gives 100, which is
the approximate gallons per minute.
To find the diameter of a pump cylinder to move a given quan-
tity of water per minute (assume piston speed of 100 ft. per min-
ute), divide the number of gallons by 4, then extract the square
root, and the result will be the diameter in inches.
Digitized by VjiOOQlC
BOILER FEED PUMPS 473
Single-Cylinder Horizontal Boiler Feed Pumps
H.p. of Boiler,
Based on 30 Lb.
Steam
Water
*§J
Gallons
, of Water per
Steam
Pipe
Ex-
Suc-
Dis-
Cylin-
Cylin-
11
per
H.p. per Hour,
haust
tion
charge
der
der
Stroke
which the Pump
Pipe
Pipe
Pipe
•
will Supply
with Ease
2K
IK
3
.022
12
Ji
X
X
K
2K
1%
4
.041
20
J*
X
1
X
3
2
4
.05
25
8.2
X
H
IX
l
3K
2M
4
.069
30
H
X
K
IX
l
4
2K
6
.13
60
■si
u ft
H
K
IK
IX
4K
3
6
.183
85
k
%
2
IK
5
3Ji
8
.28
135
K
X
2
IK
6
4
8
.435
200
S3
9*
x
1
2K
2
6
4
10
.54
250
X
1
2K
2
Is
7K
5
10
.85
400
ll
X
1
3
2K
8
5Ji
12
1.12
550
5S eS
l
IX
3
2K
9
6
12
1.47
700
1
IX
4
3
10
7
12
2.00
1,000
1
IK
5
4
12
*X
12
2.77
1,350
IK
2
6
5
.12
sx
14
3.23
1,600
IK
2
6
5
14
9H
16
4.66
2,250
IK
2
7
6
14
10
14
4.76
2,300
IK
2
8
7
14
10
16
5.44
2,700
II
IK
2
8
7
16
10K
18
6.74
3,300
To
2
2K
8
7
18
11K
18
8.09
4,000
°4
a-28
2K
3
9
8
18
11K
20
9.00
4,500
2K
3
9
8
18
12
20
9.79
isi
2K
3
9
8
20
13
20
11.49
....
2K
3
10
9
20
13
22
12.64
'Us
2K
3
10
9
22
14
24
16.00
2K
3
10
10
24
15
24
18.36
3K
4
10
10
24
16
24
20.88
3K
4
10
10
M. T. Davidson and Co., New York,
drainage purposes.
The above pumps could also be used for
Hot water cannot be lifted by suction any desirable height, and
the difficulty increases with the temperature. To handle hot water
efficiently it should flow by gravity to the pump.
Digitized by LiOOQ LC
474
MACHINERY
Vertical duplex pumps, as given in the following table, have
2 steam and 2 water cylinders. The water ends are of cast iron,
composition lined, or may be entirely of composition. For boiler
feeding these pumps have a speed of 30 to 50 single strokes per
minute, but for other services they should be run at 60 to 80.
Gallons per
>
Steam
Water
Stroke
Single
Steam
Exhaust
Suction
Discharge
Cylinder
Cylinder
Inches
Stroke of
Each Piston
Pipe
Pipe
Pipe
Pipe
4
2V2
4
.084
A
ZA
2
1H
4H
3
6
.184
A
%
*A
2
5
3M
6
.249
Va
1
3
2M
6
4
6
.326
1
IK
3
2J4
6
4
8
.435
1
W±
3
2H
7
4H
8
.55
1M
1M
4
3
8
5
10
.85
1H
2
4
3H
8
5
12
1.02
IV2
2
4
3H
9
534
10
1.03
m
2
VA
4
9
6
10
1.225
1H
2
5
4K
9
6
12
1.469
lA
2
5
4M
10
7
12
2.00
2
2^
6
5
12
8
12
2.61
2
2A
7
6
12
8M
12
2.94
2
m
7
6
14
9
14
3.85
2M
3
7
6
M. T. Davidson and Co., Nek York.
Centrifugal Pumps. — When the head for a centrifugal pump
exceeds 100 ft. including the suction, one of the stage type should
be installed. This consists of two or more impellers in separate
casings mounted on the same shaft and so constructed that the water
passes successively from one into the other, each impeller raising the
pressure.
Centrifugal pumps are often designated as low-lift and high-lift,
and sometimes are called volute and turbine pumps, but in all
the theory of operation is the same.
For ordinary marine purposes a single-stage pump is sufficient
and below is a table of direct connected centrifugal pumps of
the volute type as built by the Worthington Steam Pump Co.
Steam turbines and electric motors could be used instead of steam
3UVJV^
CENTRIFUGAL PUMPS
475
engines if desired, particularly if the head is high, as steam engine
driven pumps are suitable for comparatively low heads because
of the limited speed of the engines which run at about 400 r. p. m.
while turbines and motors run at 800 and over. On account of
the small space occupied and light weight, turbine driven pumps
have become popular. Besides handling the intake water for con-
densers, they have also worked satisfactorily for boiler feeding
and for fire purposes.
One of the chief advantages of centrifugal boiler feed pumps
is that they deliver a uniform pressure and volume at a given
speed, eliminating the vibration in the unit and piping that is
common with reciprocating pumps. Furthermore, the pressure
being kept constant, a much lower margin of difference between
the pump pressure and the boiler pressure is obtained than with
reciprocating pumps.
A volute pump has no diffusion vanes, whereas a turbine pump
has, while its casing may be either of a spiral or a circular form.
Centrifugal Pumps (Volute Type) Direct Connected to
Steam Engines
(Worthington Steam Pump Co., New York)
Engine
Pumps
Dia.
Steam
Cyl.
Stroke
Rev.
H.p.
Steam
Pipe
Ex.
Pipe
Suet.
Pipe
Disch.
Pipe
Capacity
per Min.
Ins.
Ins.
Ins.
Ins.
Ins.
Gallons
4
4
500
6.25
1
Hi
4
4
450
5
5
500
12.5
IV2
2
6
6
1,000
6
6
400
17.5
2
2
8
8
1,800
7
6
400
23.75
2
2«
10
10
2,800
8
10
325
42.75
2«
3
12
12
4,000
9
10
325
54.
3
3«
14
14
5,500
10
10
325
66.75
3
3H
16
16
7,500
11 ]
10
325
81.
3H
4
18
18
9,500
12
10
325
96.
3^
4
20
20
12,000
14
12
325
156.
VA
6
24
24
18,000
The capacities given in the above table are maximum and are
for pumps working under heads not exceeding 20"ft. An efficiency
of 65 to 75% is guaranteed by the builders on their pumps having
a discharge of over 6 ins.
Digiti
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476
MACHINERY
Centrifugal Dredging Pumps
(Worthington Steam Pump Co.)
No. Pump
(Diameter
Diameter
Cubic Yards Material
10 to 20 Per Cent.
per Hour,
3f Solids
Approximate
Horse Power
Required
for Each
10 Feet
Will Pass
Solids,
Discharge
Suction
Diameter,
Opening)
Inches
10%
15%
20%
Elevation
4
4
14
21
28
4
2
6
6
30
45
60
8
*M
8
8
60
90
120
15
6
10
10
90
135
180
25
8
12
12
125
190
250
30
10
15
15
210
315
420
50
10
18
18
300
450
600
70
10
Priming. — Centrifugal pumps that are placed above the suction
water level must be primed before starting; that is, all the air
driven out of the pump and suction pipe and the space filled with
water. When steam is available either an ejector or syphon could
fill the pump and suction pipe with water, but when so doing the
air cock on the pump must be open.
The peripheral speed in feet per minute necessary to lift water
to a given height depends on the form of the vanes. If a is a
straight radial vane, b a straight vane bent backwards, c a curved
vane its extremity making an angle of 27 degs. with a tangent to
the impeller, d a curved vane with an angle of 18 degs., and e is a
vane curved in the reverse direction so that the outer end is radial,
then
the peripheral speed in feet per min. for a = 481 \/ h
the peripheral speed in feet per min. for b = 554 \/7i
the peripheral speed in feet per min. for c = 610 \/~h
the peripheral speed in feet per min. for d = 780 y/H
the peripheral speed in feet per min. for e = 394 y/ h
where h is the head or lift in feet. As the coefficient varies with
the shape of the vanes, different speeds are necessary to hold water
to the same height. To obtain the revolutions of the vanes, divide
the peripheral speed by the circumference of the circle swept over by
the vanes (Mech. EngYs Pocket Book, W. Kent).
Doctor. — On steamers navigating the Mississippi River and
its tributaries, a combined feed pump and feed water heater called
JvJ^Vl^
AIR PUMP 477
a "doctor" is installed. This consists of a vertical beam engine
with crank and flywheel operating four pumps. Two are simple
lift pumps drawing water from the river and delivering it into the
heating chambers overhead, while the other two are feed pumps
taking their supply from the heater and delivering the water to the
boilers. Each lift and force pump is of sufficient capacity to supply
the entire battery of boilers, so that one pump of either kind may
be disconnected for examination or repair without disturbing the
regularity of the boiler feed supply.
Air Pump, see page 459.
Pumps Installed in a Freight Steamer
For particulars of the steamer Pacific (geared turbine), see
page 312.
Pumps
1 Main air, Vertical twin beam, 14 ins., 28 ins., 18 ins.
1 Circulating, Centrifugal 42-inch runner, 14 ins. dia. of
suction, engine 10 inch by 10 inch.
1 Main feed, Centrifugal, turbine-driven, 37 h. p.
1 Auxiliary. Centrifugal, turbine-driven, 37 h. p.
1 Fire and bilge, Duplex horizontal, 12 ins., 8 H ins., 12 ins.
1 Ballast, 12 ins., 10^ ins., 12 ins.
1 Trimming, 10 ins., 7 ins., 10 ins.
1 Sanitary, 7l/$ ins., 5 ins., 6,ins.
1 Fresh water, 7J^ ins., 5 ins., 6 ins.
1 Evaporator, 4J^ ins., 2% ins., 4 ins.
1 Engine room bilge, 6 ins., 5% ins., 6 ins.
2 Fuel oil, 6 ins., 4 ins., 6 ins.
Installing and Operating Pumps. — Blow out with steam all
chips and dirt in steam pipe before making final connection to
pump.
Never use a smaller pipe on the suction than the list calls for. j
Avoid right angles in the pipe, where it is possible.
Where it is practicable, make bends with a large radius and
use Y's instead of T's.
Put a foot valve and strainer on the end of the suction pipe.
Do not place the pump more than 25 ft. above the water.
Where hot water is pumped, the supply must be above the pump.
Make all joints in the suction air tight.
Keep the stuffing boxes well and evenly filled with packing.
Oil the pump before starting it, and keep the oil wiped off where
it is not needed.
In cold weather drain the steam and water cylinders to prevent
freezing.
Digitized by VjiOOQ LC
r
478 MACHINERY
For high-speed pumping and on long suction lines, have a vacuum
chamber near the pump.
Ordinarily do not run pump (reciprocating) more than 100 ft.
piston speed per minute.
For feeding boilers do not run piston (reciprocating pump)
more than 50 ft. per minute.
For boiler feeding, a check valve must be placed in the discharge
pipe near the boiler.
A pump, which when starting has pressure on its discharge
valves, will often fail to lift water. This is caused by the accumu-
lated air in the pump cylinder, which is not dislodged but merely
compressed by the movement of pump piston or plunger. To
get rid of this air, place a check valve in discharge near the pump
and a waste cock between this check valve and the pump. Run the
pump with the waste cock open until it picks up the water. If
the pump has a heavy lift, connect a priming pipe (containing
a good valve) from a supply of water to the suction pipe near the
pump. A few strokes of the pump with the priming valve and
waste cock open will enable it to catch its water.
A single double-acting pump will usually give less trouble on
heavy lifts than a duplex pump.
INTERNAL COMBUSTION ENGINES
Internal combustion engines, commonly called motors, run on
a variety of fuels, as gasoline (petrol), kerosene, distillate, and
producer gas. Crude oil can be successfully used only in Diesel
and semi-Diesel engines. Along the Atlantic Coast engines run on
gasoline and kerosene, with more running on the former than on the
latter. On the Pacific Coast distillate is popular and excellent
results are secured with it. In Europe the fuel is petrol, which is
another name for gasoline. See Oil.
Kerosene is generally cheaper than gasoline, although it is not
so powerful. Engines using kerosene do not start so quickly as
those on gasoline, and they cannot be controlled as easily. With
kerosene the engine has one certain speed at which it runs better
than at any other; consequently this fuel is suitable only for boats
running for long periods at a constant speed. It is doubtful whether
an engine using kerosene has any advantages over one using gaso-
line, when considering the adaptability to changes of speed of the
engine and freedom of carbonization that is obtained with gasoline,
even if it costs more.
Digitized by LiOOQ LC
GAS ENGINES 479
Engines running on producer gas have been installed on some
small commercial craft the builders of which have claimed low
operating costs. But gas producers take up considerable room,
and as a whole, liquid fuels are much more popular for marine use.
Engines operating on gasoline consume on an average about
one pint per horse power per hour. Kerosene engines require
about 6% more fuel than gasoline to get the same power. Diesel
engines have been run on only .54 of a pint of crude oil per horse
power per hour.
The limit of size for engines running on gasoline, kerosene, or
producer gas, where the ignition is electric or hot torch, is about
500 h. p., while those running on crude oil and operating on the
Diesel principle have been built up to 4,500 h. p.
Operation. — Engines operate on the two-cycle, four-cycle and
Diesel principle. In the former, on the upstroke of the piston
the air in the cylinder is compressed; then the fuel enters and is
ignited, thus forcing the piston down and giving the power stroke.
In the two-cycle engine there is a power stroke at every revolution
of the crank shaft.
In the four-cycle the piston draws into the cylinder on the down-
stroke the explosive mixture of air and oil vapor, which is com-
pressed on the upstroke and then ignited, the resulting explosion
driving the piston down and the return upstroke driving out the
burnt gases.
Gas or Gasoline Engines
Two-Cycle
First revolution — Downstroke: Ignition and expansion power
stroke
Lower portion of downstroke: Exhausting
gases and taking pure air in cylinders for
cleaning, and air and gas charge.
Upstroke: Compression of charge.
Four-Cycle
First revolution — Downstroke: Suction of air and gas.
Upstroke: Compression of air and gas.
Second revolution — Downstroke: Ignition and expansion power
stroke.
Upstroke: Exhaust.
The compression just prior to the explosion varies from 50 to 80
lb. per square inch (in Diesel engines it is about 750), and the
pressure of the explosion is from 150 to 300 lb. The temperature
Digitized by vjOOQ IC
480 MACHINERY
in the cylinders ranges from 1}900 to 2,000° F., except in Diesel
engines where it is from 1,000 to 1,100.
The advantages of high compression are: (1) more power
obtained from a given size of cylinder as the particles of gas and
air are forced closer together; their temperature being raised
by compression, ignition is more rapid and a better explosion is
secured; (2) gas (fuel) of poorer quality may be used with a greater
certainty of the charge igniting, for gas whieh will not ignite at
ordinary temperature and pressure may be made more combustible
at high and rapid compression; (3) higher thermal efficiency, for
a high explosive pressure allows a greater range of expansion to
follow without allowing the pressure to fall unduly low.
In the Diesel engine the air in the cylinder is first compressed
to a pressure of 450 to 600 lb. per square inch, and the liquid fuel
is forced directly into the cylinder at a pressure of about 750 lb.
The he$t due to the high compression (depending on the temper-
ature required to ignite the fuel) ignites the fuel, thus forcing the
piston down and giving the power stroke. The fuel is pumped
under pressure into the cylinder in an extremely finely divided
state by a stream of air from 150 to 300 lb. higher than that in
the cylinder. This mingling with the highly heated air charge
in the cylinder immediately ignites the fuel.
In the paragraphs immediately following are data on engines
where the mixture in the cylinders is ignited by an electric spark,
on page 492 Hot Bulb, and on page 495 Diesel.
Engines (electric ignition) may be divided into three classes,
viz., high speed, for racing boats and fast runabouts, medium
speed, for cruisers, and slow speed heavy duty, for towboats, light-
ers, and small passenger vessels. Below is a table of representative
types and on page 317 is a table of motor boats.
Horse Power Formulae for Two- and Four-Cycle Engines.
Formula.
Let P = mean effective pressure, in slow speed engines about 80 lb.
A = area of piston in square inches
S = piston speed in feet per minute (obtained by multiplying
the revolutions per minute by two times the stroke in
inches and dividing by 12)
N — number of cylinders
E =* mechanical efficiency taken at .75
C — 2.5 for two-cycle engines
4.0 for four-cycle engines
R - _ P XA XS XN XE
n* p' ~ 33,000 X C
Digitized by VjOOQ IC
ELECTRIC IGNITION 481
Internal Combustion Engines (Electric Ignition)
Num-
Revo-
Length
from Fly-
Class of Motors
Horse
Power
ber of
Cylin-
ders
Bore
Stroke
lutions
per
Minute
wheel to
Coupling
for Propel-
ler Shaft
Weight
in Lb.
High Speed
65
4
5H
6
1,200
5' 4'
950
(Van Blerck Mo-
00
4
5H
6
1,600
5' 4*
940
tor Co.) Special
100
6
5lA
6
1,200
6' 6*
1,120
135
8
5^
5*4
6
1,200
V 8*
1,450
Special
180
8
6
1,600
V 8'
1,425
Medium Speed
3-5
1
Wa.
5
550
2' 0*
325
(Frisbie Motor .
5-7
1
6
6
450
2' 3*
500
Co., Middletowat
6-10
2
*H
5
550
2' 6*
430
Conn.)
10-14
2
6
6
450
2' 9H*
700
12-18
3
*U
5
600
3' 2W
650
18-25
3
6
6
500
3' 7H"
1,050
25-30
4
/*«
5
800
3' 6*
725
30-40
4
6
550
4' 2'
1,200
-35-50
6
43*
5
600
4' 6H"
985
5£-75
6
6
6
550
5' 5*2"
1,600
Heavy Duty Wol-
verine
12-14
18-21
2
3
7
7
400
400
5' 0*
5' 10*
1,550
2,470
27
3
7H
9
350
V 6*
3,823
36
3
&A
9
350
V 6'
3,925
50
3
9H
12
300
9' 0*
6,538
75
3
11
12
300
9' 0*
7,025
100
3
12K
14
280
10' 3*
10,260
The horse powers in the above are based on using gasoline.
Another Formula.
Let d = diameter of cylinder
I — length of stroke
r = revolutions per minute
N =» number of cylinders
Then h. p. for a two-cycle engine
# XI Xr XN
13,500
d8 X I X t X N
Then h. p. for a four-cycle engine = TSOO or h. p. =
this being based on a piston speed of 100 ft. per minute.
d? X N
2.5
1017 Formula of the American Power Boat Association.
A - area of one piston in square inches
JV = number of working pistons
S = length of stroke in inches
B = maximum number of revolutions obtainable under racing
conditions
Digitized by VjiOO*
ile
482 MACHINERY
C « for 4-cycle gasoline engines 12,000
2-cycle gasoline engines 9,000
4-cycle Diesel engines 9,600
2-cycle Diesel engines 6,000
ti • j uAu A X N X S X R
For cruisers and open boats h. p. =» pj
A X N X S
displacement racers and hydroplanes, h. p. =
y
Carburetors and Vaporizers. — The former is for gasoline and the
latter for kerosene, but both have the same object, viz., to mix
the fuel with the proper amount of air to form a suitable explosive
mixture. There are a variety of carburetors on the market de-
signed for high and low speed engines and for heavy and light fuels.
The carburetor selected should be adapted to the speed of the
engine and to the fuel.
In one type for high speed gasoline engines the fuel is controlled
by a needle valve working automatically with the throttle. In
another there is a jacket around the body of the carburetor through
which the exhaust gases from the cylinders pass, thus heating the
gasoline and vaporizing it. In another make, instead of the ex-
haust gases, the hot water from the cylinder jackets is- circulated
around it.
Before installing be sure that the gasoline tank and piping are
clean and contain no particles of dirt or scale. Connect the car-
buretor to the intake pipe so it is about 6 ins. below the bottom
of the gasoline tank; for the best results it should be as close to
the cylinder as possible, and in case of multicylinder engines equi-
distant from each if practicable. The carburetor should be adjusted
to the normal running temperature of the motor.
The ordinary gasoline carburetor will not vaporize kerosene
satisfactorily, hence a special vaporizer is required. The kerosene
and air pass through a nest of heated copper tubes and by so doing
a vaporized mixture is secured. Just before the mixture enters
the cylinders a few drops of water are mixed with it, the water,
being drawn with the mixture into the cylinders, forms steam at the
time of combustion, thus permitting high compression without
preignition. To heat the copper tubes it is necessary to start the
engine on gasoline, and after it is warmed up to shut off the gaso-
line and turn on the kerosene.
Starting. — Engines of 50 h. p. and over are started by compressed
Digitized by vjOOQ LC
REVERSE GEARS
483
air or by an electric motor. In the former, when the engine is
running it drives a small air compressor that compresses air which
is stored in a tank. From this tank pipes lead to the different
cylinders. In the pipes are valves for controlling the air supply.
In the case of electric starting, the electric motor gets its energy
from a storage battery. The motor turns by means of a chain
the crank shaft of the engine, and when the latter is running the
motor is either stopped entirely or reversed, that is, turned into
a generator, and as such recharges the storage battery.
Figure 82. — Reverse Gear.
Reverse Gears. — In motor boats the motors run in one direction,
a boat being made to go ahead or astern by changing the direction
of rotation of the propeller shaft irrespective to that of the motor.
This is accomplished by a lever controlling gears housed in a casing
directly aft of the engine. The gearing is designed so that for full
speed ahead the lever is thrown way forward, for astern way aft,
and when neutral or perpendicular the boat is not under headway
although the engine may be running. For small launches, some-
times propellers with reversible blades are installed.
Fig. 82 is of a reverse gear built by Snow & Petrelli, New Haven,
Conn. The engine sleeve carries one of the central gears, into
which meshes a short pinion, which meshes with a long pinion, that
meshes with another central gear that is attached to the propeller
sleeve. Whichever way the engine runs the propeller will be
turned in the opposite direction. With this gear four revolutions
ile
484 MACHINERY
of the engine make three revolutions of the propeller in the reverse
direction.
Lubricating Systems. — Nearly every engine builder has a different
system. Some builders of two-cycle engines claim to have secured
satisfactory cylinder, connecting rod, and crank bearing lubrication
by mixing with the gasoline lubricating oil. Other builders use the
splash system, which consists of partly filling the bottom of the crank
case with oil, and as the cranks revolve, the oil is splashed over the
bearings and connecting rods. Care must be taken that the dippers
on the connecting rods barely dip into the oil, for if there is too
much oil thrown, the igniters or the spark plugs will become foul.
Most builders have adopted the force feed, the oil being dis-
tributed through pipes to the bearings and other parts by a pump,
driven from the engine shaft. The cylinder gets oil at about the
center, the oil entering at the level of the wrist pin when the piston
is down, and bpreading over the cylinder wall through grooves
in the piston. Some of the oil enters the hollow wrist pin, to which
the end of the connecting rott is fastened, and lubricates it. The
gears in the reversing gear in many instances run in a heavy oil,
while the bearings outside of the engine are fitted with grease cups.
The consumption of oil for the bearings and cylinders should
not exceed one and a half gallons per 1,000 b. h. p. A 16 h. p. en-
gine has been run 820 miles on four gallons of oil, and a 32 h. p.
1,300 miles on ten gallons. (See section on Oil.)
Cooling water required for the cylinders is approximately 8 to
10 gallons per b. h. p. The cylinders should be hot, for if they
are kept too cool there is a loss of efficiency and power. The water
is forced through the jackets by a centrifugal pump driven by
the engine, although sometimes a plunger pump is used.
Valves. — The valves controlling the entrance of the explosive
charge into the cylinder in two-cycle engines have two or three ports.
In the former, on the upstroke of the piston the charge enters
the crank case through a check valve which closes on the down-
stroke. In the three-port, the check valve is not required.
In four-cycle engines the inlet and exhaust valves are usually
operated in either of two ways: (1) the exhaust valve is cam oper-
ated with the suction of the piston operating the inlet valve on the
second or charging stroke (often, known as the automatic or suction
inlet) ; or (2) the inlet and exhaust valves are mechanically operated.
The latter arrangement is adapted for high speed engines, while
the former (1) is for slow speed heavy duty.
Digitized
by Google
WIRING DIAGRAM
485
17
Digiti
zed by G00gk
486 MACHINERY
When the valves are on the opposite sides of the cylinder, the
cylinder is known as the T type/ and when they are both on the
same side, the L; in the T two cam shafts are required while in the
L only one. Another type has the valves inverted and seated
directly on the top of the cylinder, but in this arrangement either
an overhead cam shaft or long valve lifters are required.
It is most important that the valves be correctly timed, the
exhaust valve opening soon enough that the gases will quickly pass
out and will not foul the plugs, the exhaust valve closing before
the inlet valve is opened.
Ignition. — The explosive charge may be ignited either by a hot
bulb or an electric spark. In the former a bulb in the cylinder head
is heated by a torch (see Hot Bulb Engines) requiring from 4 to 5
minutes before the proper temperature is reached. Electric ignition
is preferable to torch for pleasure boats. An idea of the number
of sparks required can be obtained from the fact that in a four-
cycle engine running at 800 r. p. m. about 400 sparks are needed
per minute for each cylinder.
Make and Break Ignition. — Electric ignition is either of the
make and break (low tension) system or the jump spark (high ten-
sion). In the former a spark is produced by the breaking of an
electric circuit the contact points of which are in the combustion
chamber of the cylinder. There is required a battery or a magneto
for generating the current, a coil, and an igniter (one for each
cylinder). (See Fig. 83.)
The current is led to a coil consisting of a core of soft iron wires
around which are wound several layers of heavy insulated copper
wire. The current, after passing through the coil, goes to the
terminals of the igniter which consists of a fixed and a movable
electrode, the latter being operated by the rise and fall of a rod
the end of which bears on a shaft that is driven by the main shaft
of the engine by gears. The contact points of the igniter are often
tipped with platinum-iridium, which insures long wear and clean
points.
One of the advantages of the make and break system is that
it is not easily affected by dampness and is consequently largely
adopted for engines installed in open boats. Its disadvantages
are that there are moving parts within the cylinder, and it is only
suitable for slow speed engines.
Jump Spark or High Tension System. — Here (see Fig. 84) the cur-
rent is transformed from a primary or low tension to a high tension
Digitized by vjOOQ LC
SPARK COILS 487
by a spark coil, and then as a high tension current it is led to the spark
plug in the top of the cylinder, the current jumping across the gap
between the points of the plug and by so doing creating a spark.
It is evident that the spark must be controlled, otherwise there
would be one continuous spark between the points of the plug.
The controlling of the spark is accomplished either by a timer or
a distributor.
Spark coils for high tension ignition are different from those
of low tension ignition in that they are covered with another winding
of fine insulated copper wire; that is, they consist of a core of soft
iron wire around which is wound a few layers of coarse copper
wire called the primary coil, on top of which is wound a great many
layers of fine insulated copper wire called the secondary coil but not
connected with the primary. When a low voltage current is broken
in the primary coil, a high voltage one is induced in the secondary,
and this goes to the spark plugs.
A coil is necessary for each spark plug, hence for each cylinder
when a timer is used. The coils can either all be placed in a com-
mon box or a combined coil and plug made which is screwed into
the top of the cylinder just like an ordinary spark plug. With a
distributor (see Timers and Distributors) only a single coil is re-
quired.
High tension .systems are particularly adapted for high speed
engines, and there are several types on the market. For instance,
the dual, where the cylinders have two plugs, one when running
on the batteries and the other when on the magneto.
Timers and Distributors. — The time of ignition can be controlled
in the jump spark system by a timer driven from the engine shaft,
which completes the primary circuit between the battery or magneto
and the spark coil at the proper instant at which the ignition of
the charge in the cylinder must take place. If a timer is used without
any other device, then a separate coil is required for each cylinder.
A distributor is a modification of a timer enabling a single coil
to ignite a multicylinder engine. The distributor gives the proper
distribution of the secondary current of the induction coil to each
cylinder at the proper time.
Thus a timer works on the primary or low tension current, and
with a timer, coils are required for each cylinder, while a distributor
works on a secondary or high tension current, requiring only one
coil for a multicylinder engine.
A system which has proved satisfactory is the Kent (A. Kent
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MACHINERY
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TIMING THE IGNITION 489
Mfg. Co., Philadelphia, Pa.), in which, in addition to the usual
battery or magneto for generating the current, there is a device called
a unisparker, consisting of a mechanical contact maker, a high tension
distributor, and a non-vibrating spark coil. The unisparker is
driven from the engine, giving one spark per revolution, the im-
portant feature in its construction being that it produces a spark
of constant strength irrespective of the speed of the engine, and that
the battery circuit is never closed except at the instant of the spark.
Thus the engine can never stop so as to leave the ignition circuit
closed if the switch is accidentally left on. As a result of the small
current consumed, a set of ordinary dry cells will last several weeks.
Timing the Ignition. — The timing of the ignition of a single-
cylinder jump spark engine is outlined below, but the same pro-
cedure is followed irrespective of the number of cylinders.
Open the priming cup or take off one of the spark plugs and put
a piece of stiff wire in the cylinder so that one end rests on the top
of the piston. Then by noting the rise and fall of the wire as the
crank shaft is turned, the position of the piston at any part of the
stroke can be determined. (1) Turn the engine so that the piston
is on the top of the compression stroke. (2) Turn the flywheel
about 10° more, always in the direction in which the engine is to
run, so that the piston is about 10° past the high center point, and
then put the timer in place with the contact points of the timer
together forming a circuit. Now wire the timer to the spark coil
(see section on Electricity).
Magnetos are small generators for furnishing the current for
ignition purposes and are driven from the main engine by belts,
gears, or by direct contact with the flywheel. There are two
types, viz., low and high tension. The low is for either jump
spark or make and break ignition, while the high is only for jump
spark. A low tension magneto generates a primary current, hence
a coil is required to increase it to a higher voltage. By having the
proper ratio between the revolutions of the shafts of the low tension
magneto and of the engine, as say four to one, the engine may be
started without a battery. A low tension magneto in a jump
spark circuit requires a separate spark coil for each cylinder, but
when in a make and break only one coil is needed.
High tension magnetos are only for jump spark ignition and
differ radically from the low as neither a spark coil nor a timer is
necessary. In the high tension there are two windings, a high
and a low, and a circuit breaker that breaks the circuit in the high
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490 MACHINERY
tension winding. This is located at the end of the magneto shaft
and can be rocked backward and forward, thus serving to advance
or retard the spark. The function of the circuit breaker is to
interrupt the primary current, thereby causing an induced high
tension current in the secondary winding which goes direct from the
distributor binding post to the spark plug. No coil or timer is
necessary, as these magnetos have a complete ignition system
within themselves, having their own windings and a circuit breaker
that takes the place of a timer.
The advantage of a high tension magneto is that a hot spark
is generated and as there is only one circuit breaker for the primary
circuit which is alike for all cylinders, more accurate timing is
secured than by separate vibrating coils. These magnetos are
gear driven from the engine, and as they are more sensitive than
the low they must be carefully protected from the weather. On
small engines that can be cranked 50 or more revolutions a minute,
the engines can often be started direct on high tension magnetos,
no batteries being required, but for larger sizes batteries are gen-
erally necessary.
Spark plugs are for igniting the explosive mixture in the com-
bustion chamber. Preferably the spark between the points should
be in the form of a flat sheet rather than a ball, for a spark with an
extensive surface or area will ignite a greater number of mixture
particles in a given time than will a thin threadlike spark. The
plug should be located near the intake valve in such a manner that
it will be surrounded by the fresh gas that enters during the inlet
stroke. If on the exhaust side, dead gas is liable to collect around
the points and cause missing.
If the engine misses, examine the spark plugs. Clean off the
mica or porcelain and see that the points are about & of an inch
apart. To test the plug, unscrew it and lay it on the cylinder
head or other part of the engine where there is no paint. Attach
a wire to the plug, but only let the outside or shell of the plug rest
on the cy Under. Turn the flywheel until contact is made at the
timer. If the vibrator does not buzz, adjust the screw until it works
properly, then notice the size of the spark at the points of the plug.
If no spark occurs take the plug apart and clean it. Then if, on
reassembling, again no spark occurs, look for bad vibrator points
or exhausted batteries, broken wire, or loose connections. Too
much or too poor cylinder oil, and too rich a mixture, will cause
the plug to foul and become sooted.
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BATTERIES
491
Batteries. — See section on Electricity.
Motor Trouble. — The following applies to two- and four-cycle
electric ignited gasoline engines. If after cranking the engine four
or five times it does not start, see that the fuel is turned on, that
the electric switch is thrown in, and that there is nothing caught in
the shafting. If the engine starts, then slows down, and finally
stops, the fuel supply is chocked or the batteries have given out.
Should the compression be weak, see if any of the spark plugs are
loose, or perhaps the valves leak, or there may be a broken piston
ring. If the valves leak they should be reground. This is done by
taking out the valve, putting a grinding compound on the seat,
replacing the valve and turning it to the right and left until a clean
smooth surface is on the valve face. Care should be taken in grind-
ing that none of the compound gets into the cylinder; if it does it
should be removed.
If the engine will not start, begin a systematic search for trouble,
beginning with the carburetor and then going over the ignition sys-
tem.
Part
Carburetor
Trouble
Water in gasoline or in carburetor.
Air valve or the needle valve is out of adjustment.
Ignition System Spark plugs dirty or short circuited (see Spark
Plugs).
Broken cable or poor connection at the terminals.
Vibrator out of adjustment or points burned.
Weak batteries.
Timer dirty.
See if magneto is revolving in the direction of
rotation stamped on the end.
Open the circuit breaker and see that it is not
flooded with oil and there is no oil on the con-
tact points.
Dirty spark plugs.
Backfires in carburetor, too lean a mixture.
Valves leak.
Batteries weak.
Wrong spark plug gap.
Connections loose.
Engine not bolted firmly to its foundation.
Piston ring broken.
Shaft bearing loose.
Connecting rod loose.
Water circulation stopped. See if sea cock is
open, pump working, and the pipes not
clogged up.
Cylinder getting no oil.
Engine runs but
misses
Engine pounds
Cylinders get
very hot
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492 MACHINERY
If the engine begins to backfire, this indicates that the gasoline
tank is empty or the supply pipe is stopped up. Should the engine
stop suddenly this may be caused by the electric circuit being
accidentally broken or the supply of fuel stopped.
Abstracts from Motor Boats, by Chas. H. Hughes, perm. Am. Tech. Soc., Chi-
cago.
Hot Bulb Engines
In hot bulb (sometimes called/ semi-Diesel) engines no electric
ignition is required, there being instead a bulb which is first heated
by a torch. After the engine has started the torch may be put
out, as the heat produced by the explosion of the fuel in the cylinder
is sufficient to keep the bulb hot. The compression is from 85 to
215 lb. per square inch, and the pressure from the explosion 260 to
350 lb.
Engines of this type have proved very satisfactory for medium size
seagoing vessels and have been installed in many sailing vessels
(see page 318). They are reliable, their fuel consumption is low and
a cheap grade can be used. They are built in sizes up to about
500 h.p. A well-known make is the Bolinder (built by J. and C. G.
Bolinder, New York) which is of the two-cycle type with a working
pressure of about one-third that of a Diesel engine. Complete com-
bustion is obtained by mixing the fuel with air before injecting it
into the cylinder. For this purpose a special nozzle has been con-
structed in which the fuel oil is automatically mixed with air. No
water injection in the cylinders is necessary at normal load or 10%
overload. The engine can run on cheap and heavy oils.
All Bolinder engines having more than one cylinder are started
by compressed air. The ignition balls are heated (from 7 to 15
minutes being necessary, depending on the size of the engine), and
when ready to start, open the cylinder cocks to avoid compression
in the cylinders and turn the flywheel until the mark on it is on top,
in which position the piston has just commenced its downward
stroke. Next close the cylinder cocks. The stop valve on the air
receiver is now opened and the hand wheel of the starting valve is
opened 2 or 3 turns, after which by means of a hand lever the valve
is opened for a moment, allowing air to enter the cylinder, and is
quickly closed, the engine readily starting.
This engine is also direct reversible, the reversing being accom-
plished as follows:
1. The clutch is thrown out by means of a hand lever.
2. The reversing lever is pulled aft (for going astern). This
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REVERSIBLE ENGINES
493
movement causes the engine to slow down at once; a charge of oil
if. automatically injected at the appropriate stage of the cycle and
the movement of the piston is immediately reversed.
3. The reversing lever is returned to its central position.
4. The clutch is thrown in again.
The reversing is done by two hand levers. To change from astern
to ahead the procedure is exactly the same except that the reversing
lever is thrown over in the opposite direction.
Figure 85.— Hot Bulb Engine (Bolinder Co., New York).]
The following table gives particulars of the engines.
Bounder's 4-Cylinder Direct Reversible Engines
Brake horse power
80
425
8,700
42
100
385
12,600
45
160
325
22,800
55
240
275
33,600
63
320
225
44,400
75
500
Revolutions per minute
Weight in pounds (approx.).. .
Diameter of propeller (3 blades)
inches
160
89,600
106
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MACHINERY
Another hot bulb engine is the two-cycle Skandia built by the
Skandia Motor Works, Lysekil, Sweden. One of the features of
this engine is that it works without water injection. When running
without load or with a small load many engines require no water
injection owing to the fact that only a small quantity of heat is
imparted to the walls of the combustion chamber. If the load is
increased, the heat will rise to a high degree, especially in case of
overload, so that the walls, if not water cooled, become red hot,
thereby causing advance ignition. Apart from the space required
by water tanks, the water injection has an injurious influence upon
the life of an engine. In a Skandia, the water-cooled cylinder cover
makes water injection unnecessary.
In direct connection with the governor is the fuel pump which is
worked through the medium of a cam. By means of an adjusting
screw, combined with the governor, the fuel feed may be regulated
instantaneously while the engine is running, and after the stroke
of the pump has been adjusted to suit the load of the engine the
engine will run continuously with the same number of revolutions.
When the fuel supply is properly adjusted the exhaust gases are
smokeless.
All engines of 25 h.p. and over are supplied with a starting device
consisting of a starting valve and steel air tank connected by copper
piping. The engine can be started by a pull on the handle of the
starting valve.
Skandia engines are built in three types: (1) direct reversible
like a steam engine, which is secured by means of • compressed air;
(2) with a reversing gear; and (3) with a reversible propeller.
Skandia Oil Engines (Direct Reversible)
Cons, of Fuel
Approx-
Number of
Brake
Revolutions
in Lb. per
B.H.P. Hour
imate
Cylinders
Horse Power
per Minute
Gross Weight,
at Full Load
Pounds
4
90
375
6.6
14,960
4
120
375
6.38
15,906
4
140
325
6.38
18,480
4
200
300
6.38
20,570
4
240
300
6.27
29,700
4
385
250
6.16
56,100
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DIESEL ENGINES 495
Diesel Engines
Engines working on the Diesel principle do not require an ignition
system, as the fuel is ignited by being forced into cylinders of com-
pressed air. The pressure in the cylinders is from 400 to 600 lb.
per square inch (depending on the fuel) and as the fuel must be
injected at a higher pressure, say 750 lb., an air compressor is
required. These engines are started and reversed in many instances
by compressed air, and the space occupied by them is about 80% of
a steam engine and boiler of the same power.
Diesel engines have been installed in many freight vessels (see
page 316), and on account of their low operating costs (see page 335)
due to cheap fuel and the small number of men required, they have
proved very satisfactory on certain routes. Submarines are driven
by them when running on the surface.
Care must be exercised in the selection of fuel, because one which
is suitable for one make of engine may not be for another having a
different compression or system of atomization. It is an object to
use the cheapest fuel possible but in a general way Diesel engines
cannot use crude oils. The fuels which they do require are easily
obtainable and cost very little more than crude oil. Most Diesel
engines are guaranteed to run. on crude oil of a certain gravity, but
this gravity is so high that there are few crude oils that will comply
with it. When an engine runs well on an oil of a given viscosity, it
is advisable to get oil as near this viscosity as possible, otherwise the
entire adjustment of the injection valves must be altered. How-
ever, a heater may be installed utilizing the warm gases from the
exhaust for heating the oil.
A fair average consumption in a Diesel engine on the basis of
brake horse power per hour when using fuel with a heating capacity
of 18,500 B. t. u. per pound can be taken as .40 lb. per horse power
hour for large engines and .46 for small. On this basis, considering
that oil weighs 7.5 lb. per gallon, the fuel consumption per 100 b.
h. p. hours would be about 6 gallons.
k The table on page 496 gives a comparison of Diesel engines,
ordinary reciprocating marine engines, and geared turbines. Al-
lowance has been made for the difference in tonnage measurement
and deadweight capacity which the systems involve. The vessel
chosen is 400 ft. long between perpendiculars, 52 ft. beam, 29 ft.
9 ins. deep, and 26 ft. 1 in. draft. Total deadweight carrying capac-
ity in tons, 8,640 (steam), 8,775 (Diesel), 8,805 (geared turbines).
Speed 10 ^ knots, radius of action 3,500 miles, fuel consumption 1 .6
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MACHINERY
lb. per i. h. p. per hour (reciprocating), 1 .2 lb. per i. h. p. per hour
(turbine),. .61 lb. per i. h. p. per hour (Diesel).
' Oil Engine
Steam Engine
Geared Turbine
Capital Invested
$381,000
$308,000
$351,000
•
Per
Voyage
Per
Month
Per
Voyage
Per
Month
Per
Voyage
Per
Month
$2,390
1,700
537
537
$2,170
3,590
$1,800
2,666
488
488
$1,738
3,590
$2,050
Fuel (oil at $9.77, coal at
$3.66)
Wages and provisions
Wear and tear
$1,756
' 1,950
439
Deck and engine room
488
Port charges, at $1 .22 per
ton
3,680
$5,436
87,000
62.000
$5,164
$5,760
92.200
57,300
$4,776
$5,328
85,300
59,200
$4,927
12 months
$149,000
19,000
2,440
$149,500
15,400
2,440
$144,500
17,550
2,440
Freight-earning cargo car-
ried, tons
$170,440
16 X 8,530
= 136.480
$167,340
16 X 7,880
- 126.080
$164,490
16 X 7,910
= 126.560
170,440:00
136,480.00
$1.25 per ton
167,340.00
126,080.00
$1.33 per ton
164.490.00
126,560.00
$1.30 per ton
In general, for moderate speed ships which would be driven by
a single reciprocating engine, a Diesel engine ship is more costly as
the machinery is more expensive and the hull also, on account of
the twin screws, oiltight work, etc., but the space occupied by pro-
pelling machinery is less and the weight is less, so that there is a
gain in cargo-carrying capacity and weight. See Costs. At the
present state of development, Diesel engines are not suitable for
high-powered vessels from engineering rather than economic reasons.
General Features. — For a given horse power the cylinder of a
Diesel engine is J to i the diameter of a steam cylinder, while
the rods and bearings are about the same size as in a steam engine
of the same power. The pistons fit the cylinders very closely and
are usually j^-t of an inch smaller in diameter at the top than at
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TWO-CYCLE ENGINE
497
the bottom, to allow for the expansion due to heat. Six to eight
rings are fitted haying lapped joints, so that there is no leakage past
the piston.
Diesel engines are either two- or four-cycle. In the two-cycle
engine there is one working or power stroke with every revolution.
This type of engine has a scavenger pump operated directly from the
main engine, or scavenger pistons which are extensions of the power
pistons that furnish the air required for clearing the working cylinder
of its burnt gases and for filling it with fresh air which is then com-
pressed on the return of the piston. When the exhaust valves are
open, air from the scavenger pump is admitted through mechanically
Figure 86.— End Elevation— Werkspoor Diesel Engine.
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498 MACHINERY
operated valves at the piston end of the cylinder, and sweeps before
it the products of combustion, leaving the cylinder filled with fresh
air which is then compressed on the return stroke of the piston.
The two-cycle engine is more complicated than the four, and has in
some cases 10% higher fuel consumption. However, it has the ad-
vantage of saving considerably in weight.
In the four-cycle type, on the down or intake stroke the air is ad-
mitted through mechanically controlled air inlet valves. On the
up or return stroke this air is compressed to 400 to 600 lb. per square
inch, and thereby becomes heated to a temperature of around
1,000° F. A few degrees before the completion of the compression
stroke, the liquid fuel is injected into the engine cylinder through the
oil injection valves and atomizers by means of highly compressed
injection air. furnished by an independent high pressure compressor.
This high-pressure air atomizes the oil, breaking it up into a mist
which on coming in contact with the hot air in the engine cylinder
is burned and gasified. The gases force the piston down on the third
or working stroke, expanding gradually, much as steam expands in a
cylinder after being cut off. On the fourth stroke the burned gases
are expelled through the discharge or outlet valve into the exhaust
pipe. The piston sweeps all the gases before it and acts as an effi-
cient scavenger. The fuel inlet valve in the four-cycle engine is
built very heavy and as it operates against high pressures it
has a small movement and remains open from about % of the stroke
to the minimum cut-off.
Below are cycles of Diesel engines in a tabular form.
Two-Cycle
First Revolution Downstroke Injection of charge and ignition
by heated air.
Lower portion of Exhausting gases and taking in
downstroke pure air for cleaning cylinders.
Upstroke Compression of air to 1,000° F.
Four-Cycle
First Revolution Downstroke Suction of pure air.
Upstroke Compression to 1,000° F.
Second Revolution Downstroke Injection of fuel charge, ignition
by contact with heated air,
expansion, power stroke.
Upstroke Exhaust of gases.
The fuel to the injection valves is usually pumped by a twin
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INJECTION VALVE 499
plunger, one plunger doing most of the work and discharging the
excess through an escape valve back into the suction. The second
plunger is somewhat smaller and accurately measures the fuel forced
through the injection valve. On the largest engines these plungers
are about % to J^ inch in diameter with a small stroke.
The fuel is atomized by air pressure varying from 600 to 1,200 lb.
per square inch, according to the make of engine and the fuel. This
pressure is obtained by a three- or four-stage compressor sometimes
attached to the main engine, or to an auxiliary engine, and in some
cases to both. The air from the compressor is stored in steel bottles
for starting, the bottles having sufficient capacity to turn over the
engine for about 10 minutes.
Injection Valve. — This valve may be raised by cams and returned
to its seat by powerful springs. Various devices have been resorted
to in order to minimize friction in the stuffing box. Some com-
panies use an oil lantern in the middle of the stuffing box; others
ehminate the stuffing box entirely, having instead a stem about 1}^
ins. in diameter and 18 ins. long, fitting closely in a sleeve with oil
grooves instead of packing. The timing of the injection valve, its
control by the governor, and the timing of the fuel pumps are the
most delicate adjustments on Diesel engines.
Timing of Valves. — For the air inlet and exhaust valves the only
adjustment actually necessary is to compensate for the wear of
the valves, and this is done by lengthening the valve stems by
sleeves.
Suction valves open about 5° below top center and close on the
bottom center. Exhaust valves open 10° or 12° below the bottom
center and close near the top center. All valves are closed during
compression, expansion, and ignition, except the fuel inlet which
has a lead of 5° to 10° depending on the speed of the engine, the fuel,
and the type of injection valve.
Operating Notes. — To start a Diesel engine the air valve to the
compressed air supply is opened, and after the engine has made a
few revolutions the governor lever is moved and the injection valves
begin to act. It is then run slowly until warmed up, as one of the
greatest troubles with Diesel engines is the cracking of the cylinders
owing to the constant changes of temperature.
During this period a round of the engine should be made to inspect
the action of the valves, try the pet cocks, examine jacket water
for temperature, and otherwise make sure that the engine is running
satisfactorily. The engine should run for about 20 minutes at less
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500
MACHINERY
Figure 87a. — Section of motor ship, 40J.5ft. between perpendiculars; displace-
ment at 26 ft. draft 12,100 tons; 2, 6-cylinder Burmeister & Wain engines, 24.8 in.
diameter by 37.75 in. stroke, 130 r. p. m., each developing 1550 h. p. (Fig. from
Int. Mar. Eng'g, New York.)
than full speed, but if necessary can be brought up to full speed in
4 or 5 minutes, but it should not be unless means are provided for
circulating hot water through the engine jackets.
Engines which have failed on certain kinds of oil have run well
by raising the pressure of the atomizing air, or by preheating the
oil, or in other ways improving the atomization. If an engine
smokes and shows carbon, this may be caused by one of the following
Digiti
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TYPES 501
(1) The fuel is not being atomized.
(2) The compression is not high enough.
(3) There is an excess of fuel.
If the fuel does not atomize it may be because the viscosity is
too high. In some cases this can be remedied by preheating the
fuel or increasing the amount and pressure of the air for atomizing,
but some of the heavier residual fuel oils are so viscous and have
such surface tension that it is impossible to atomize them into the
fine mist necessary for clean combustion. If the engine has not
sufficient compression use a ligher fuel that is more easily ignited.
Types. — Tables 1 and 2 are of engines built by the New London
Shipbuilding Co., which are of the two-cycle type. Table 1 gives
data on engines for Navy use and for high speed yachts where min-
imum weight is required, which runs from 45 to 50 lb. per h. p.
depending on the size. This weight includes all auxiliary machinery
and apparatus as water and oil pumps, fuel pumps, air pumps,
coolers and filters, as well as the entire reversing apparatus with
compressed air receivers. Engines of the same over-all dimensions
can be furnished of heavier weight, viz. 60 to 65 lb. per h. p. for
medium duty, while heavy weight slow speed engines averaging 97
lb. are given in Table 2.
The above engines are of the single acting two-cycle type. On
the upstroke of the piston pure air is compressed in the working
cylinder to a high pressure and thereby becomes heated to a tempera-
ture above the flash point of the fuel oil. Shortly before the end of
the upstroke, a spray valve opens and fuel oil is delivered, for a short
time at the beginning of the downstroke, into the cylinder, and begins
to burn. This downstroke is the real working stroke. At the end
of this stroke the burned gases are exhausted, and the cylinders are
scavenged and filled with pure air which is then compressed and
the cycle repeated.
Another engine operating on the Diesel principle and of the
two-cycle type is the Southwark-Harris valveless engine. The cycle
of operations is as follows: (1) the fuel pump places a small quan-
tity of crude or fuel oil in the atomizer at a certain time in the revo-
lution of the engine and leaves it there; (2) the scavenging pump
blows out the previous charge through the exhaust and leaves a
charge of pure air in the cylinder when the piston is at the end of
its outward stroke; (3) the piston then compresses the charge of
pure air into such a small space that it becomes very hot; and (4)
the atomizer spindle is lifted by the cam shaft, opening the passage
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502 MACHINERY
Table 1 — Data for Light Weight High Speed Engines
Number
Normal
Maximum
Normal
Fuel Con-
Weight
Lb. About
of
Brake
Brake
R. p. m.
sumption
Lb. About
Cylinders
Horse Power
Horse Power
About
6
300
330
480
0.52
14,500
6
450
500
450
0.50
22,550
6
600
660
425
0.49
27,000
6
900
975
390
0.48
39,000
6
1,200
1,275
370
0.48
52,000.
6
1,500
1,600
300
0.47
65,000
6
2,000
2,150
270
0.47
86,000
Table 2 — Data fob Heavy Weight Moderate Speed Engines
Number
Normal
Maximum
Normal
Fuel Con-
Weight
Lb. About
of
Cylinders
Brake
Horse Power
Brake
Horse Power
R. p. m.
About
sumption
Lb. About
6
300
350
300
0.49
32,000
6
600
650
275
0.47
62,000
6
900
1,000
235
0.46
91,000
6
1,200
1,300
210
0.46
115,000
6
1,500
1,600
180
0.45
140,000
6
2,000
2,100
165
0.44
188,000
The weights given include all auxiliary machinery and apparatus, such as water
and oil pumps, fuel pumps, coolers and filters, as well as the compressed air starting
and injecting apparatus, and thrust block.
New London Shipbuilding Co.
into the cylinder, and the injection air forces the oil lying in the
atomizer into the hot charge in the form of a spray. The oil im-
mediately ignites and further heats the charge of air and causes
same to expand behind the piston and thereby transmit power to
the crank shaft as steam does in a steam engine. There is no
explosion and the pressure does not materially exceed the 500 lb.
compression pressure, but owing to the additional heat supplied by
the burning of the oil the expansion creates the power.
The important features in the Southwark-Harris engine are
that cold high-pressure air is never admitted into the working
cylinders, and that the engine can be started from stone cold to full
power in 10 seconds and can be started or reversed without cutting
off the fuel from any of the main or working cylinders.
The scavenging pump or low-pressure compressor is of the
Digiti
zed by G00gk
DIESEL ENGINES
603
step piston type; that is, the piston of the scavenging pump is an
enlarged extension of the main piston, working in its own cylinder
below the working cylinder. It is while reversing and starting the
engine on compressed air that the scavenging cylinder and step
piston play an important part. The using of the step piston in air
starting does away with the necessity of air starting valves in the
cylinder head, the scavenging air being admitted to the working
cylinder through ports in its circumference. The exhaust gases
pass out through ports located opposite the scavenging ports and
so arranged that the piston opens and shuts them at the correct
time during its travel.
The table below gives data on Southwark-Harris engines.
Southwark-Harris Diesel Engines*
Normal
Approx-
Number
Dia. of
Stroke,
Ins.
Dia. of
Revo-
imate
of
Cylinder,
Shaft,
lutions
Weigh o
I. h. p.
Cylinders
Ins.
Ins.
per
Without
Minute
Wheel, Lb.
2
9
13
5
300
14,000
120
4
9
13
5
300
21,500
240
6
9
13
5
300
31,000
360
8
9
13
5
300
40,000
480
4
12
21
8
200
47,000
450
6
12
21
8
200
66,000
675
8
12
21
8
200
85,000
900
4
16
28
11
150
800
6
16
28
11
150
1,200
8
16
28
11
150
1,600
* Southwark-Harris Co., Philadelphia, Pa.
Diesel engines, built by Burmeister and Wain, Copenhagen,
Denmark, have been installed on many large vessels. These
engines are of the 4-cycle type, and all the large sizes have 6 cylin-
ders cast in blocks of 3. With the present design it is claimed there
is no danger of cracked cylinders as liners are fitted of special grade
cast iron similar to the heads of the piston. The air compressors
are self-contained and are operated from the end of the crank shaft.
Six A frames support the cylinders and to them are bolted the cross-
head guides. The frames have through bolts on both sides which
extend from the top of the cylinders to the under side of the bed
plate bearings. The pistons are only long enough to contain the
Digitized by vjOOQ 1C
504
MACHINERY
rings and are cooled with sea water like the cylinders. One of the
largest built (1916) was a 6-cylinder, 4-cycle with cylinders 29.6 ins.
diameter by 44 ins. stroke, giving 340 h. p. per cylinder at 100 r. p. m.,
with a total of 2,040 h. p. for the engine. See Fig. 87a.
Refer to the table of Motor Ships and note the 336-footer in
which were installed two Burmeister and Wain engines. Each is
of the 4-cycle type with six cylinders 21 x/i ins. diameter by 28 %
ins. stroke, and develops about 1,000 h. p. The engines are inclosed
and are fitted with a high-pressure oiling system. The valve gear
is reversible by sliding the cam shaft and substituting a special
set of cams for reversing. Each cylinder has its own fuel pump,
which draws from day settling tanks of 12-hour capacity. In the
exhaust lines are two mufflers, one at each engine and one in the
deck house above with branches to the masts, the masts being hol-
low and of steel.
Figure 87. — Section Through Cylinder of a Werkspoor Engine.
Another make of Diesel engine which has been built in sizes up
to 2,000 h. p. is the Werkspoor, built by the Netherlands Eng'g Co.,
Amsterdam, Holland, and by the Newport News Shipbuilding
Company, and New York Shipbuilding Company, in the United
States. One of the features of this engine is its accessibility, it
being of the open type with the cylinders mounted on steel columns
on both sides, and at the back are cast iron frames on which are
the crosshead guides. The cylinder design (see Fig. 87) differs
from other four-cycle Diesels, there being no detachable heads,
and the absence of flanges affords proper water cooling all around
that part of the combustion chamber which is exposed to the
jvJ^X^
CRAIG ENGINES
505
greatest heat. The engine can be reversed from full ahead to
astern in about 5 seconds, and can be started up from cold in 3 to
5 seconds, on an air pressure of 250 lb. per square inch. The
engine is self-contained and does not require a large amount of
separate auxiliary machinery. The exhaust gases are led in some
vessels to a donkey boiler and sufficient heat is obtained to maintain
a pressure of 100 to 120 lb. when at sea. The average consumption
of Werkspoor engines including auxiliaries is about .3 lb. of oil per
i. h. p. per hour.
Werkspoor Diesel Engines
i
Number of
Cylinders
Diameter
of
Cylinders
Stroke
Revs,
per
Min.
Approximate
Weight with
Compressor
and Pumps,
Founds
Normal
B. H. P.
Normal
I. H. P.
4
12^
16«
23J3
200
51,520
200
265
3
26^
200
67,200
250
300
4
15JS
26^
175
80,640
340
450
4
19^
31M
140
134,400
450
600
6
WA
265^
175
130,000
475
635
6
20^
35^
130
215,040
825
1100
6
22
39M
125
273,280
1020
1360
6
MM
43^
120
349,440
1320
.1760
6
26
47M
110
425,600
1500
2000
Still another make is the Craig (James Craig Engine and Machine
Works, Jersey City, N. J.), the builder guaranteeing less than one
half pound of fuel per brake horse power per hour. Almost any
grade of fuel oil can be burned, but there are some, owing to high
sulphur content, great viscosity, etc., that are undesirable. Craig
engines are of the 4-cycle, direct reversible type and are built in
sizes from 180 to 1,000 h. p. with 6 to 8 cylinders, each cylinder
being a separate casting bolted to a rigid table carried on stanchions
mounted in the bed plate. This style of framing affords an open
crank case.
The valves in the cylinder heads are operated by push rods
and rockers, so arranged that the heads can be detached and re-
placed without disturbance of any adjustments. At the back of
the cylinders are located the lower exhaust ports, controlled by
valves through which the exhaust pressure's released at the end of
the power stroke.
Digitized by LiOOQ LC
506
MACHINERY
A compressor furnishes the air for the injection fuel and for
replenishing the storage bottles containing the air for starting
and reversing. The compressor is of the two-stage type with
intermediate and final air coolers of large surfaces.
The engine is reversed by affixing to the front cam shaft suit-
able cams arranged to function the valves for the ahead motion
and suitable cams to function the valves for the astern motion,
together with suitable inclines on the sides of the cams to lift and
lower the push rods when necessary; and by arranging the cam
shaft to move longitudinally in its bearings.
Fuel is fed to the injection valves by a single pump with a stroke
that is variable at will, giving close regulation of the engine speed. '
From the pump the fuel is forced through adjustable distributor
valves with graduated scales, fitted in convenient positions on
the engine. Below are tables of sizes.
Heavy Duty Series
B. h. p.
Cylinders
Dimensions
R. p. m.
Wt. of Engine
200
360
500
Six
Six
Eight
9K" X 12"
12^" X 15*
12J^" X 15"
420
375
380
16,500 lb.
28,000 lb.
37,000 lb.
Slow Speed Series
200
300
540
Six
Six
Si£
9%* X 15*
12" X 18"
16" X 24"
320
260
200
21,600 lb.
34,000 lb.
64,500 lb.
Diesel Engine Installations. — The auxiliaries may be grouped
under two headings: (1) those for operating the ship; and (2) those
pertaining to the propelling equipment.
Under (1) is included bilge, ballast, fire, sanitary, and fresh
water pumps common to both Diesel and steam driven vessels,
as also the refrigerating plant and the electric outfit, although the
latter may have a direct connected Diesel engine and generator.
Cargo winches, windlasses, capstans, and steering gear are gener-
ally steam operated but could be electric, the steam being furnished
by a donkey boiler.
The propelling equipment includes air starting reservoirs that
JvJ^VLV^
PIPING AND TUBING 507
may be arranged vertically against the bulkheads or horizontally
in tiers, while the fuel injection air tank is close to the engine, the,
piping being of copper.
The main engine cylinders are cooled by sea water supplied by
a pump driven from the engine. The water may be discharged into
a tank above the engine, thus flowing by gravity through the cyl-
inder jackets and thence overboard.
Exhaust piping is led to a muffler that may be placed in a stack
extending above the deck. The piece next to the engine is of
cast iron, so as to withstand the high temperatures of the exhaust
gases, although the rest of the piping may be ordinary wrought iron
which should be covered with asbestos or other insulating material.
The turning gear is generally arranged with teeth in the periphery
of the flywheel and may be operated by hand, steam, compressed
air, or electricity.
See table of Motor Ships and Fig. 87a.
PIPING, TUBING, VALVES AND FITTINGS
Piping and Tubing. — When the size of a wrought iron pipe is
given as J^ inch, neither the actual outside nor inside diameter is
this dimension; this is an arbitrary dimension that has been fixed
by the pipe manufacturers. See tables on pages 508-9. Wrought
iron pipe is usually joined by screwed couplings on all sizes below
5 ins., and above this size by flanges with bolts.
Butt-welded wrought iron pipe is 70% as strong as similar butt-
welded steel pipe, and lap- welded wrought iron pipe is 60% as
strong as similar lap-welded steel pipe. In steel the butt weld
averages 73% of the tensile strength and the lap weld 92% of the
tensile strength of the material.
The principal advantage claimed for wrought iron pipe over 3teel
is its resistance to rust and corrosion. To distinguish wrought iron
pipe from steel, after removing all marks of the cutting off tool
and having the end of the pipe smooth, suspend the pipe so that the
end will dip into a solution of 10 parts water and 4 parts sulphuric
acid, 1.84 sp. gr., say XA ounce acid and l\i ounces water. Keep
immersed for about an hour. Remove the pipe, wash off the acid
and dry quickly with a soft rag. If the pipe is steel, the end will
present a solid unbroken surface, if iron the end will show ridges
or rings indicating different layers of iron and streaks of cinder.
There are certain trade customs as follows: The permissible
variation in weights is 2J/£% below standard weights given in tables
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Digiti
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510
MACHINERY
and not over 5% above standard weights. All standard weight
pipe unless otherwise ordered, is shipped in random lengths, threaded
and furnished with couplings. Extra strong and double extra strong
pipe, unless otherwise ordered, is shipped with plain ends and in
random lengths without couplings. Random lengths for strong and
double extra strong are considered to be from 12 to 24 ft., mill to
have the privilege of supplying not exceeding 5% of the total order
in lengths from 6 to 12 ft. For bundling schedule see page 20.
"National" Stationary and Marine Boiler Tubes
All Weights and Dimensions are Nominal
Outside Diameter, Inches
Thickness
Inches
Thicknesf?
Birming-
ham Wire
Gauge
Weight
per Foot,
Pounds
Test Pressure, Lb.
beamless
Seamlc
Hot
Coir
Lap
i Weld
»ss Lap Weld
Finish
Finis
h
1
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13
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1.171
100c
>
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1.425
100c
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100c
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2
2
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13
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100c
) 750
2*A
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: 2K
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2.186
10(X
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2V2
2M
1 2J4
.109
12
2.783
1(XX
) 750
2%
2*/4
: 2^
.109
12
3.074
100(
) 750
3
3
3
.109
12
3.365
1(XX
) 750
3M
3^
1 3K
.120
11
4.011
100(
) 750
3H
&A
i 3^
.120
11
4.331
100(
) 750
s%
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1 3^
.120
11
4.652
1(XK
* 750
4
4
4
.134
10
5.532
1(XK
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VA
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10
6.248
MXX
) 500
5
5
5
.148
9
7.669
1<XX
) 500
6
.165
8
10.282
500
7
.165
8
12.044
500
8
.165
8
13.807
500
9
.180
7
16.955
500
10
.203
6
21.240
500
11
.220
5
25.329
500
12
.229
28.788
500
13
.238
i
32.439
500
In tubing the actual outside diameter is given. Boiler tubes are
generally of charcoal iron, lap welded. The physical properties of
boiler tubes as manufactured by the National Tube Co., Pittsburgh,
Pa., are as follows:
Digiti
zed by G00gk
BOILER TUBES
511
"National"
Spellerized
Shelby
Seamless
Cold-drawn
Shelby
Seamless
Hot finished
Tensile Strength, lb. per sq. in
Elastic Limit, lb. per sq. in
Elongation ui 8 inches, per cent
Reduction of area, per cent
58,000
36,000
22
55
52,000
32,000
22
50
62,000
42,000
22
48
Iron and Steel Lap-Welded Boiler Tubes
External
Imperial
Equiva-
External
Imperial
Equiva-
Diameter
Wire
lents in
Diameter
Wire
lents in
in Inches
Gauge
Inches
in Inches
Gauge
Inches
IN
13
.092
5N
7
.176
IN
13
.092
6
7
.176
IN
13
.092
6N
7
.176
IN
13
.092
6N
7
.176
IN
13
.092
6M
7
.176
IN
13
.092
7
7
.176
2
12
.104
7N
5
.212
2N
12
.104
7Vi
5
.212
2M
12
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5
.212
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11
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11
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11
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3
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3
11
.116
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3
.252
3N
10
.128
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3
.252
3H
10
.128
9N
3
.252
3M
10
.128
10
3
.252
4
9
.144
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2
.276
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9
.144
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2
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VA
9
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1
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11
1
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5
8
.160
UN
1
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5M
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.160
12
1
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5H
7
.176
Brass tubes have a maximum tensile strength of 40,000 lb. per
square inch when made with a mixture to the ratio of 60 lb. of cop-
per to 40 lb. of zinc, and will stand bending on themselves and
flanging when either hot or cold without fracture.
Copper tubes made from absolutely pure copper have a maximum
tensile strength of 30,000 lb.
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Digiti
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Table Showing Approximate Weight
Stubs7 or Birmingham Gauge
(To ascertain the weight of Seamless Copper Tubing
Gauge No.
To determine weight per foot of a tube of a given
weights given below under
Gauge No.
3
4
5
6
7
8
0
10
11
12
13
14
Increase in
Lb. per Ft.
1.5487
1.3077
1.1174
.9514
.7480
.6285
.5057
.4145
.3324
.2743
.2084
.1590
The above Weights are theoretically correct, but variation* mutt be
514
Per Foot op Seamless Brass Tubing
Measured in Outside Diameters.
Add 5 per cent to the Weights of Brass Tubing.)
Gauge No.
15
16
17
18
19
20
21
22
23
24
25
26
27
Thickness of each
No. in Decimal
Parts of Inch
.072
.065
.058
.049
.042
.035
.032
.028
.025
.022
.020
.018
.016
Frac. of Inch, Cor-
responding Closely
to Gauge Nos.
A
V«
V«
l/u
Dia. Tubes, Ins.
y%
.045
.092
.139
.186
.233
.279
.326
.373
.420
.467
.514
.561
.608
.655
.70
.79
.89
.98
1.08
1.17
1.26
1.36
1.45
1.55
1.64
1.73
1.83
1.92
2.01
2.11
2.20
2.30
2.39
2.48
2.58
2.67
2.76
2.86
.045
.087
.129
.170
.212
.254
.296
.338
.380
.421
.463
.505
.547
.589
.63
.71
.80
.88
.96
1.05
1.13
1.22
1.30
1.38
1.47
1.55
1.63
1.72
1.80
1.89
1.97
2.05
2.14
2.22
2.30
2.39
2.47
2.56
.043
.078
.114
.149
.184
.220
.255
.290
.326
.361
.396
.432
.467
.502
.54
.61
.68
.75
.82
.89
.96
1.03
1.10
1.17
1.24
1.32
1.39
1.46
1.53
1.60
1.67
1.74
1.81
1.88
1.95
2.02
2.09
2.16
.040
.070
.101
.131
.161
.192
.222
.252
.283
.313
.343
.373
.404
.434
.46
.52
.59
.65
.71
.77
.83
.89
.95
1.01
1.07
1.13
1.19
1.25
1.31
1.37
1.43
1.49
1.55
1.62
1.68
1.74
1.80
1.86
.036
.062
.087
.112
.137
.163
.188
.213
.238
.264
.289
.314
.339
.365
.389
.439
.490
.540
.591
.641
.692
.742
.793
.843
.894
.944
.995
1.045
1.096
1.146
1.197
1.247
1.298
1.348
1.399
1.449
1.50
1.55
.084
.057
.080
.104
.127
.150
.173
.196
.219
.242
.265
.288
.311
.334
.358
.404
.450
.496
.542
.588
.635
.681
.727
.773
.819
.866
.912
.958
1.004
1.050
1.096
1.143
1.189
1.235
1.281
1.327
1.373
1.42
.031
.051
.072
.092
.112
.132
.152
.173
.193
.213
.233
.253
.274
.294
.314
.351
.395
.435
.476
.516
.556
.597
.637
.678
.718
.758
.799
.839
.880
.920
.960
1.001
1.041
1.082
1.122
1.162
1.203
1.243
.029
.047
.065
.083
.101
.119
.137
.155
.173
.191
.209
.227
.245
.263
.281
.317
.354
.390
.426
.462
.498
.534
.570
.606
.642
.678
.714
.750
.786
.822
.859
.895
.931
.967
1.003
1.039
1.075
1.111
.026
.042
.058
.074
.090
.106
.121
.137
.153
.169
.185
.201
.217
.232
.248
.280
.312
.343
.375
.407
.439
.470
.502
.534
.566
.597
.629
.661
603
.024
.039
.053
.067
.082
.096
111
.125
.140
.154
.169
.183
.107
.211
.226
.255
.284
.313
342
.371
.399
.428
.457
.486
.515
.544
.573
.022
.035
.048
.061
.074
.087
.100
.113
.126
.139
.152
.165
.178
.191
.204
.230
.256
.282
.308'
.334
.360
.386
.412
0?0
A
.096
.148
.200
.252
.304
.356
.408
.460
.511
.563
.645
.667
.719
.77
.87
.98
1.08
1.19
1.29
1.39
1.50
1.60
1.71
1.81
1.91
2.12
2.23
2.33
2.43
2.54
2.64
2.74
2.85
2.95
3.06
3.16
03?
yK
043
A
055
%
066
A
078
J*..~
w
.089
101
Y%
11?
\\
124
si
136
«/m
148
yH
159
»/m
171
1
18?
lVg
205
m
??8
1=4
?51
iu
?74
i£ :::.::::
IX
1*8
2
214
2l4
23 s
2H
2%
.724
.756
.788
.820
.851
.883
.915
.946
.978
zyH
3H
3*6
zv2
TfiA
3»4
VA
Inside Diameter, add to weights in above list the
corresponding gauge numbers.
Gauge No.
15
16
17
18
19
20
21
22
23
24
25
26
27
Increase in
Lb. per Ft.
.1197
.0975
.0777
.0554
.0407
.0283
.0230
.0181
.0144
.our
.0092
.0075
J0059
expected in practice. From Catalogue of U. T. Hungerford Co.
515
y Google
516
MACHINERY
Table Showing Approximate Weight
Stubs' or Birmingham Gauge.
(To ascertain the weight of Seamless Copper Tubing
Gauge No.
3
4
5
6
7
8
9
10
11
12
Thickness of each
No. in decimal
Parts of Inch
.250
.238
.220
.203
.180
.165
.148
.134
120
.109
Prac. of Inch, Cor-
responding Closely
to Gauge Nos.
H
»/«
»/<*
A
»/e4
V«
K
Dia. Tubes, Ins.
11.19
11.57
11.94
12.32
12.69
13.06
13.44
13.81
14.18
14.56
14.93
15.31
15.68
16.05
16.43
16.80
17.17
17.92
18.67
19.42
20.16
20.91
21.66
22.41
23.07
23.82
24.56
25.30
10.33
10.68
11.02
11.36
11.71
12.05
12.39
12.74
13.08
13.42
13.77
14.11
14.45
14.80
15.14
15.48
15.83
16.51
17.20
17.89
18.57
19.26
19.95
20.64
21.27
21.95
22.62
23.30
9.60
9.91
10.23
10.55
10.87
11.18
11.50
11.82
12.14
12.45
12.77
13.09
13.41
13.72
14.04
14.36
14.67
15.31
15.94
16.58
17.21
17.85
18.48
19.12
19.69
20.32
20.96
21.60
8.90
9.19
9.48
9.77
10.07
10.36
10.65
10.95
11.24
11.53
11.82
12.12
12.41
12.70
13.00
13.29
13.58
14.17
14.75
15.34
15.92
16.51
17.10
17.68
18.20
18.80
19.37
19.97
7.94
8.20
8.46
8.72
8.98
9.24
9.50
9.76
10.02
10.28
10.53
10.79
11.05
11.31
11.57
11.83
12.09
12.61
13.13
13.65
14.17
14.69
15.21
15.73
16.33
16.87
17.38
17.90
7.31
7.54
7.78
8.02
8.26
8.50
8.73
8.97
9.21
9.45
9.69
9.92
10.16
10.40
10.64
10.88
11.12
11.59
12.07
12.54
13.02
13.50
13.97
14.45
15.03
15.51
15.99
16.47
6.58
6.79
7.01
7.22
7.43
7.65
7.86
8.07
8.29
8.50
8.71
8.93
9.14
9.35
9.57
9.78
9.99
10.42
10.85
11.28
11.70
12.13
12.56
12.98
13.49
13.91
14.35
14.47
5.98
6.17
6.37
6.56
6.75
6.94
7.14
7.33
7.53
7.72
7.91
8.11
8.3)
8.49
8.69
8.88
9.07
9.46
9.85
10.23
10.62
11.01
11.39
11.78
12.22
12.62
13.01
13.40
5.37
o.55
5.72
5.89
6.06
6.24
6.41
6.58
6.76
6.93
7.10
7.28
7.45
7.62
7.80
7.97
8.14
8.49
8.84
9.18
9.53
9.87
10.22
10.57
10.96
11.32
11.66
12.00
4.89
4Vd
5.05
AVi.
5.21
m
5.37
4^4
5.52
452
5.68
\\i :.
5.84
J&. ..::::
6.00
5
6.15
5H
6.31
5$.::.::.:
6.47
5U
6.62
5*£
6.78
h% \
6.94
fM\
7.10
514
7.25
6
7.41
6^
7.72
6V$ •..
8.04
6'4
8.35
7
8.67
1M
8.98
7W
9.30
7J?
9.61
8
9.97
%M
10.30
8H
10.61
8%:::. ::::::::..
10.92
To determine weight per foot of a tube of a given
weights given below under
Gauge No.
3
4
5
6
7
8
9.
10
11
12
Increase in
Lb. per Foot
1.5487
1.3077
1.1174
.9514
.7480
.6285
.5057
.4145
.3324
.2743
The above Weighti are theoretically correct,
Digiti
zed by G00gk
BRASS TUBING
517
Per Foot op Seamless Brass Tubing
Measured in Outside Diameters.
Add 5 per cent to the Weights of Brass Tubing.)
Gauge No.
13
14
15
16
17
18
19
20
21
22
23
24
Thickness of Each
No. in Decimal
Parts of Inch
.095
.083
.072
.065
.058
.049
.042
.035
.032
.028
.025
.022
Frac. of Inch, Cor-
responding Closely
to Gauge Nos.
V*
V«4
A
Vn
V«
Dia. Tubes, Ins.
4
4.28
4.42
4.56
4.69
4.83
4.97
5.11
5.24
5.38
5.52
5.65
5.79
5.93
6.07
6.20
6.34
6.48
6.75
7.03
7.30
7.57
7.85
8.12
8.40
8.71
3.75
3.87
3.99
4.11
4.23
4.35
4.47
4.59
4.71
4.83
4.95
5.07
5.19
5.31
5.43
5.55
5.67
5.91
6.15
6.39
6.63
6.87
7.11
7.35
7.63
3.26
3.37
3.47
3.58
3.68
3.78
3.89
3.99
4.09
4.20
4.30
4.41
4.51
4.61
4.72
4.82
4.93
5.13
5.34
5.55
5.76
5.96
6.17
6.38
6.64
2.95
3.05
3.14
3.23
3.33
3.42
3.52
3.61
3.70
3.79
3.89
3.98
4.08
4.17
4.26
4.36
4.45
4.64
4.83
5.01
5.20
5.30
5.58
5.76
7.05
2.64
2.72
2.81
2.89
2.97
3.06
3.14
3.22
3.31
3.39
3.48
3.56
3.64
3.73
3.81
3.89
3.98
4.15
4.31
4.48
4.65
2.23
2.30
2.38
2.45
2.52
2.59
2.66
2.73
2.80
2.87
2.94
3.01
3.08
3.15
3.22
3.29
3.37
3.51
3.65
3.79
3.93
1.92
1.98
2.04
2.10
2.16
2.22
2.28
2.34
2.40
2.46
2.52
2.58
2.65
2.71
2.77
2.83
2.89
1.601
1.651
1.702
1.752
1.803
1.853
1.904
1.954
2.005
2.055
2.106
2.156
2.207
2.257
2.308
2.358
2.409
1.466
1.512
1.558
1.601
1.650
1.697
1.743
1.789
1.835
1.881
1.928
1.974
2.02
1.284
1.324
1.364
1.405
1.445
1.486
1.520
1.566
1.607
1.147
1.183
1.219
1.255
1.291
1.010
4H
4lA
4%
4H
m
4%
4J4
5
5%
5l4
hV%
5H
b%
5H
5%
6
6*4
6^6
6*£
7
714
71^
754
8
8H
8lA
$%
Inside Diameter, add to weights in above list the
corresponding gauge numbers.
Gauge No.
13
14
15
16
17
18
19
20
21
22
23
24
Increase in
Lb. per Ft.
.2084
.1590
.1197
.0975
.0777
.0554
.0407
.0283
.0236
.0181
.0144
.0112
but tariationa must be expected in practice.
18
Digiti
zed by G00gk
518
MACHINERY
Copper pipes over 5 ins. diameter are usually of sheet copper with
the edges brazed together.
Seamless Brass and Copper Pipe — Iron Pipe Sizes
Made to Correspond with Iron Pipe and to Fit Iron Pipe Size Fittings
Weight
per Foot
Same aa
Outsids
Diameter
Inside
Diameter
Iron Size
Brass
Copper
Inches
Inches
Inches
Lb.
Lb.
Vs
.405
.281
.25
.260
H
.540
.375
.43
.450
Vs
.675
.494
.62
.650
H
.840
.625
.90
.960
%
1.05
.822
1.25
1.310
1
1.315
1.062
1.70
1.790
itf
1.66
1.368
2.50
2.630
iyi
1.90
1.600
3.00
3.150
2
2.375
2.062
4.00
4.200
2H
2.875
2.500
5.75
6.04
3
3.50
3.062
8.30
8.72
3^
4.00
3.500
10.90
11.45
4
4.50
4.000
12.29
13.33
m
5.00
4.500
13.90
14.60
5
5.563
5.062
15.75
16.54
6
6.625
6.125
18.45
19.23
To determine the Safe Working Pressure for seamless brass
and copper tubing in pounds per square inch, multiply the tensile
strength (see above) by the thickness of the metal in inches or
decimal parts of an inch, and divide the product by the radius
(one-half the inside diameter of the tube) expressed in inches,
and the quotient will be the bursting pressure in pounds per square
inch. Divide this bursting pressure by a factor of safety, say 6,
which will give the safe working pressure. See Strength of
Materials.
The U. S. Steamboat-Inspection Rules give the following formula
for the thickness of copper steam pipes. Thickness in inches =
P X D
— h .0625, where P = working pressure in lb. per sq. in., and
D = inside diameter of the pipe in inches.
Digitized
by Google
BENDING PIPES AND TUBES
519
Seamless Copper Tube
Hard Drawn, in 12-Foot Lengths
Stubs'
Gauge
Outside
Weight
Stubs'
Gauge
Outside
Weight
Diameter
Inches
per Ft.
in Lb.
Diameter
Inches
per Ft.
in Lb.
21
H
.036
10
2}€
3.43
21
A
.060
12
2M
2.82
20
X
.091
10
2H
3.84
20
A
.118
12
2V2
3.16
19
%
.169
14
VA
2.44
19
A
.202
10
2M
4.25
18
a
.268
12
2%
3.49
18
A
.304
11
3
4.19
18
H
.312
14
3
2.93
17
H
.486
10
3K
5.06
17
%
.574
10
33^
5.47
16
1
.730
14
3K
3.43
16
IN
.830
10
&A
5.87
15
1M
1.03
10
4
6.28
14
IN
1.30
14
4
3.94
14
IN
1.43
10
4M
6.69
14
IN
1.55
10
4M
7.09
13
1«
1.91
10
4M
7.50
13
2
2.20
10
5
7.91
14
2
1.93
10
6
9.52
Bending Pipes and Tubes. — The radius a pipe or tube is bent
to should never be less than 5 diameters, and a length of straight
pipe equal to 2 or 3 diameters should be provided at each end for
handling in the process of bending. When bending welded pipes
the weld should always be on the side of the pipe when bent,
never on the outside of the curve and not on the inside if it can be
avoided.
Flow of Water through Pipes and Sizes of Pipes. — A fair velocity
is. 100 ft. per minute. To find the velocity in feet per minute
necessary to discharge a given volume of water in a given time,
multiply the number of cubic feet of water by 144 and divide the
product by the area of the pipe in inches.
To find the area of a required pipe, the volume and velocity
of water being given, multiply the number of cubic feet of water
by 144 and divide the product by the velocity in feet per minute.
The area being found, to get the diameter refer to table of areas
Digitized by vjOOQ 1C
520
MACHINERY
or divide by .7851 and take square root of the quotient. Or diam-
eter of pipe = 4.95 J Gallons Per minute
y velocity in feet ner min
velocity in feet per minute
Velocity ofr Flow op Water
In Feet per Minute, Through Pipes of Various Sizes, for Varying
Quantities of Flow
Gallon*
per Minute
HI*.
1 In
Vi Ina
]'ij hlH
2 1 KH.
2% Ins
.. In*.
4 in
5
218
122%
78%
54%
30%
19%
13)4
7%
10
436
245
157
109
61
38
27
15%
15
653
367%
235*4
163%
9114
58)4
40%
23
20
872
490
314
218
122
78
54
30%
25
1090
612%
392%
272%
152%
97)4
67)4
38)4
30
735
451
327
183
117
81
46
35
857%
549%
381 %
213%
136)4
94)4
53%
40
980
628
436
244
156
108
61%
45
1102%
706%
490%
274%
175%
121)4
69
50
785
545
305
195
135
76%
75
1177%
817%
457%
292)4
202)4
115
100
1090
610
380
270
153%
125
762%
487)4
337%
191%
150
915
585
405
230
175
1067)4
682)4
472%
268%
200
1220
780
540
306%
Loss in Pressure
Due to Friction in Pounds per Square Inch for Pipe 100 Feet Long
By G. A. Ellis, C. E.
Gallons
Discharged
Hln.
1 In.
1% Ins.
1% Ins.
2 Ins.
2% Ins.
3 Ins.
4 Ins.
per Minute
5
3.3
0.84
0.31
0.12
10
13.0
3.16
1.05
0.47
0.12
15
28.7
6.98
2.38
0.97
20
50.4
12.3
4.07
1.66
0.42
25
78.0
19.0
6.40
2.62
0.21
0.10
.
30
27.5
9.15
3.75
0.91
.... *
35
37.0
12.4
5.05
40
48.0
16.1
6.52
1.60
45
20.2
8.15
50
24.9
10.0
2.44
0.81
0.35
0.09
75
56.1
22.4
5.32
1.80
0.74
100
3.90
9.46
3.20
1.31
0.33
125
14.9
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2.85
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200
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521
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522
MACHINERY
Flanges for wrought iron pipe are attached in a variety of ways,
the most common for sizes from 1}^ to 15 ins. is to screw the flanges
on the pipe. Or for sizes larger than 6 ins. the flanges may be
shrunk on and the pipe peened over or expanded into a recess in
the flange face, after which the flange is sometimes faced off on
a lathe.
Flanges for copper pipe may be brazed on. The U. S. Steamboat-
Inspection Rules state: "The flanges of all copper steam pipes
over 3 ins. in diameter shall be made of brass or bronze composi-
tion, forged iron or steel, or open hearth steel castings and shall
be securely brazed or riveted to the pipe. Flanges shall not be
Standard Companion Flanges for Steam: Working Pressures
up to 125 LB.
Flanges of cast iron, ferro-steel, forged steel, and malleable iron,
for wrought iron pipe
Size
Dia.
Thick-
Dia.
Length
Dia. of
Num-
Size
Length
Dia. of
of
of
ness of
of
of
Bolt
ber
of
Bolt
Pipe,
Flange,
Flange,
Hub,
Thread,
Circle,
of
Bolts,
Bolts,
Holes,
Ins.
Ins.
Ins.
Ina.
Ins.
Ins.
Bolts.
Ins.
Ins.
Ins.
H
VA
A
\y2
X
2X
4
H
i*
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l
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I in
tt
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From Crane Co., Chicago.
Digiti
zed by G00gk
TENSILE STRENGTH
523
less than 4 times the required thickness of pipe, plus one-fourth
of an inch, and shall be fitted with such number of good and sub-
stantial bolts as shall make the joints at least equal in strength
to all parts of the pipe."
The tensile strength per square inch of various materials for
pipe flanges is as follows: ordinary grade cast iron 14,000, high
grade cast iron 22,500, ferro-steel 33,500, malleable iron 37,000,
forged steel 51,000, cast steel 67,000.
Flanges may have the following faces: plain face, raised face
smooth finish for gaskets, raised face finished for ground joint,
tongue and groove, male and female, plain face corrugated and
plain face scored. Plain straight face is for pressures less than 125
lb., and raised smooth face or tongue and groove for high pressures.
Extra Heavy Companion Flanges for Working Pressures
up to 250 LB.
Flanges of cast iron, ferro-steel, cast steel, and malleable iron, for
wrought iron and steel pipe
Size
. Dia.
Thick-
Dia.
Length
Dia. of
Num-
Sise
Length
Dia. of
of
of
ness of
of
of
Bolt
ber
of
of
Bolt
Pipe,
Fange,
Flange,
Hub,
Thread,
Circle,
of
Bolts,
Bolts,
Holes,
Ins.
Ins.
Ins.
Ids.
Ins.
Ins.
Bolts
Ins.
Ins.
Ins.
1
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27
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IN
7N
IN
From Crane Co., Chicago.
y Google
524
MACHINERY
Screw Threads for Bolts and Nuts. — In the United States the
standard is the Sellers, having a thread angle of 60 degs., the thread
being flattened at the top and filled in at the bottom, the width
of the flat in both cases being one-eighth of the pitch and the depth
of thread is .649 X pitch. In Great Britain the standard is the
Whitworth, having a thread angle of 55 degs., round at top and
bottom, and a depth of .640 X pitch.
Bolts and Nuts
U. S. Standard screw threads, for dia. at root and tests see page 93.
Hexagonal Heads
Square Heads
and Nuts
and Nuts
Height,
Dia. of
Threads,
Per In.
Hex. or
Bolt, Ins.
Sq. Head
Long
Short
Long
Short
or Nut
Dia.
Dia.
Dia.
Dia.
Vx
ft
20
18
8
H
ft
ft
k
If
K
5
1~6
Vs
16
ft
ft
ft
1 1
K
ft
14
ft
ft
lii
ft
ft
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l
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m
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K
ft
12
IK
ft
IK
ft
ft
%
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i*
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IK
lft
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lft
IK
lft
IK
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%
9
lft
lft
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8
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IK
1
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7
2ft
lft
2ft
2ft
lft
IK
IX
7
2ft
2
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1«
6
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2ft
IK
m
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w
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m
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IK
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Screw Threads — Whitworth or British Standard
Dia.
Threads
Per In.
Dia.
Threads
Per In.
Dia.
Threads
Per In.
Dia.
Threads
Per In.
Dia.
Threads
Per In.
X
H
H
20
18
16
14
12
12
u
11
11
10
10
9
9
1
VA
IK
l«
m
m
8
7
7
6
6
5
IX
2
25i
5
4«
4
3H
3
ax
3'3
3
2 3
SCREW THREADS
525
Screw Threads for Pipe. — The standard in the United States is
the Briggs. The thread has an angle of 60 degs., is rounded at
top and bottom, so that the depth of the thread =
g
The thread is perfect for a distance
number of threads per inch*
from the end of the pipe
.8 dia. of pipe -f 4.8
then there
number of threads per inch'
are two threads flat at the top but perfect at the bottom, and then
four threads imperfect at the top and bottom. The taper of the
pipe at the end is ■& in. per in., that is ?V m- on e»ch side. In Great
Britain the standard is the Whitworth, having the same thread
form as for Whitworth bolts and nuts, the threads being cut either
straight or with a taper of ^ in. per in.
Standard U. S
Pipe Threads
Nominal
Size of
Pipe, Ins.
Dia. of
Pipe at
Top of
Thread,
Ins.
Dia. of
Pipe at
Bottom
of
Thread,
Ins.
Number
of
Threads
Per In.
Nominal
Size of
Pipe, Ins.
Dia. of
Pipe at
Top of
Thread,
Ins.
Dia. of
Pipe at
Bottom
of
Thread,
Ins.
Number
of
Threads
Per In.
X
.393
.334
27
ax
3.938
3.738
8
H
.522
.433
18
4
4.434
4.234
8
8
.656
.568
18
*X
4.931
4.731
8
.815
.701
14
5
5.490
5.290
8
H
1.025
.911
14
6
6.546
6.346
' 8
1
1.283
1.144
UH
7
7.540
7.340
8
IX
1.626
1.488
UX
8
8.534
8.334
8
IX
1.866
1.728
UH
9
9.527
9.327
8
2
2.339
2.201
nx
10
10.645
10.445
8
2X
2.819
2.619
8
11
11.639
11.439
8
3
3.441
3.241
8
12
12.632
12.432
8
Whitworth or
British
Standard Pipe Threads
Nominal
Size of
Pipe, Ins.
Dia. of
Pipe at
Top of
Thread,
Ins.
Dia. of
Pipe at
Bottom
of
Thread,
Ins.
Number
of
Threads
Per In.
Nominal
Size of
Pipe, Ins.
Dia. of
Pipe at
Top of
Thread,
Ins.
Dia. of
Pipe at
Bottom
of
Thread,
Ins.
Number
of
Threads
Per In.
X
.383
.337
28
3
3.460
3.344
11
X
.518
.451
19
SX
3.700
3.584
11
%
.656
.589
19
SH
3.950
3.834
11
%
.825
.734
14
ax
4.200
4.084
11
.902
.811
14
4
4.450
4.334
11
S
1.041
.950
14
4^
4.950
4.834
11
1.189
1.098
14
5
5.450
5.334
11
1
1.309
1.193
11
5X
5.950
5.834
11
IX
1.650
1.534
11
6
6.450
6.334
11
ft
1.882
1.766
11
7
7.450
7.322
10
2.116
2.000
11
8
8.450
8.322T
10
2
2.347
2.231
11
9
9.450C
9.322
2X
2.587
2.471
11
10
10.450
10.322
2X
2.960
2.844
11
11
11.450
11.290
8
2X
3.210
3.094
11
12
12.450
12.290
8
526
MACHINERY
Packing and Gaskets for Pipe Flanges. — The flanges are first
covered with plumbago or lamp black, and then the gasket put
on; after which the nuts on the flange bolts are tightened up. Pack-
ing comes in rolls from which the gaskets are cut, or the gaskets
can bs purchased already cut to size. For high-pressure super-
heated steam, a packing composed of long fiber asbestos and rubber
with a brass wire insertion has given satisfactory results. For low-
pressure steam and cold water, rubber packings are used. In some
cases metal packing is required, and here corrugated copper has
given good service.
Length of Thread on Pipe that is Screwed into Valves or
Fittings to Make a Tight Joint
Size of Pipe, Ins.
LeDgth of Thread, Ins.
Site of Pipe, Ins.
Length of Thread, Ins.
X
X
3^
iA
x
X
4
i&
x
X
m
IX
X
X
5
1*
%
X
6
IX
l
A
7
1&
IX
%
8
IX
IX
X
9
IX
2
tt
10
IX
2X
tt
12
IX
3
l
Nipples and Couplings. — Nipples are pieces of standard pipe
threaded at each end. When the threads meet at the center the
pipe is called a close nipple, and if a small amount of unthreaded
surface is left a short nipple. Other nipples are classified as long
and extra long, the latter ranging from 4 to 12 ins., the length in-
creasing by even inches. Nipples are threaded either right hand or
right and left hand.
Couplings are of wrought iron and are threaded internally for
receiving the ends of the pipes to be joined. They are threaded
either right hand or right and left hand.
Unions are classed under two headings, viz., nut unions and flange
unions. The former are ordinarily for 2-inch pipe and smaller, and
are of malleable iron, brass and malleable iron, or all brass. Flange
unions are for sizes larger than 2 ins. and are of cast iron or malleable
iron, in three weights, standard, extra heavy, and hydraulic.
Digitized by V^OOQ IC
PIPING SYSTEMS
527
Materials for Piping Systems.
Fire main
copper
Water service
brass
Boiler feed
copper
Steam
copper or steel
Exhaust steam
copper or wrought iron
Main drain
wrought iron
Steam heating
Ammonia and brine
wrought iron
wrought iron or mild steel
The fittings in ammonia piping when screwed should be of extra
heavy malleable iron with recessed ends for soldering. Flanged
fittings should have a male and female portion.
In some instances where there is little pressure and the temperature
is not much above the normal atmosphere, the pipe may be of lead.
Its indifference to iron and steel as regards galvanic action makes it
a suitable material for bilge suction pipes. Lead piping is often
used for the discharge from toilets on motor boats, where, owing to
the cramped quarters, it is impossible to fit any other kind.
The factor of safety for steam piping should never be less than 6,
for there are stresses due to expansion and contraction, water ham-
mer and vibration which must be allowed for. Corrosion must also
be considered. In laying out a steam line, care must be taken to
give it easy bends to allow for contraction and expansion. In some
instances slip joints are fitted. According to one authority, Briggs,
the effect of each right angle bend is equivalent to increasing the
Figure 88.— Globe Valve— Rising Wheel.
Digitized
by Google
528 MACHINERY
length 40 diameters, and that of each globe valve is equivalent to
increasing the length 60 diameters.
Valves, Cocks and Fittings are of cast iron, malleable iron, com-
position, and of cast steel either screwed or flanged. They may be
classified as follows:
1. Low pressure for pressures up to 60 lb. per square inch.
2. Standard pressure for working pressures up to 125 lb. per square
inch.
3. Medium pressure for working pressures up to 125-175 lb. per
square inch.
4. High pressure for working pressures up to 175-250 lb. per
square inch.
5. Hydraulic for water pressure up to 800 lb.
All fittings on wrought iron pipe over 6 ins. should be flanged and
should have gaskets between the flanges. Even when the piping
is of small size and with screwed couplings, there should be an occa-
sional flanged fitting for ease in making up the piping.
The distinguishing feature between a valve and a cock is the
amount of bearing and tightening surface. Valves bear and grind
upon a narrow and small seat when closed, whereas cocks bear and
grind upon a wide and long seating surface. The wear in valves
is much less, and they are kept tight much easier under high pressure
than cocks. Cocks, however, can be opened quicker.
In purchasing a valve the following points should be noted: that
it has sufficient weight of metal to prevent its being bent or sprung
when connected with the piping; that it has valve seats that are
easily repaired, freedom from pockets, and is arranged so the stem
can be packed under pressure.
Valves of 3 ins. and smaller usually have screw tops, while those
of larger sizes have yokes. For high pressure, the outside yoke and
screw pattern is preferable as the engineer is able to tell at once the
position of the gate. Valve bodies are generally of brass for small
sizes up to 2J^ ins. and of cast iron, semi-steel, or steel for those larger.
There are two kinds of stems, one rising when the hand wheei is
turned, the hand wheel remaining stationary, and the other has the
hand wheel rise with the valve stem. Valves of 6 ins. and over
should have by-passes for ease in opening.
Globe and angle valves have circular seats, and their important
features are strength and tightness. Globe valves should be set
to close against pressure, for if placed the opposite way they could
not be opened if the valve became detached from the stem. An
Digitized by vjOOQ 1C
CHECK VALVES
529
angle valve is a form of globe valve with the inlet at the bottom and
outlet at the side.
Check Valves. — When the flow of steam or water is always in
one direction check valves are installed, the valves closing themselves
should the direction of flow be changed. There are several forms on
the market, some with a swing valve, others spring controlled.
Gate Valves. — Here the closing portion slides in a groove, and their
face to face distance is less than in globe valves of the same size.
They should never be placed in a steam line with the spindle down.
They are made either with a rising stem or a rising wheel.
Figure 89. — Gate Valve— Rising Stem.
Reducing Valves. — To reduce the pressure from a higher to a
lower, as to reduce the steam from the boiler to a pressure of 15 lb.
or less for heating purposes.
Butterfly valves have the valve pivoted. Sometimes a valve of
this type is placed near the engine throttle valve. Is, however,
y Google
530 MACHINERY
largely for ventilating systems and elsewhere where the pressure is
small. In butterfly and in gate valves the passages through them
are straight, thus forming practically a section of the pipe to which
they are fitted.
Throttle Valve, see Engine Fittings.
Blow-off Valves should always be installed on the boiler so that
the pressure will come on top of the disk. They should be opened
wide when blowing off, so as to save the disks and seats from wear.
These valves are liable to be cut by scale and other boiler impuri-
ties, and hence it is essential to select one so constructed that it can
be repaired quickly. Some have removable seat rings.
Atmospheric Exhaust Relief Valves are placed in branches from
the main exhaust line leading to the atmosphere. They remain
closed while the vacuum is maintained in the condenser, but should
the vacuum be lost the valve will automatically open, permitting the
engine to exhaust freely into the atmosphere until the vacuum is
restored, when the valve will close again.
Kingston Valve. — Here water enters when the valve disk is pushed
outward from its seat. Should the valve stem break, the disk would
be forced back on its seat again and thus act as a non-return valve.
These valves are chiefly for sea injection, and have been installed on
many submarines.
Manifold. — A rectangular cast iron chest containing several
valves by which compartments and pumps may be so connected that
one or more pumps may be used to pump out a compartment. At the
bottom of the manifold are connections to the suction pipes, and at
the upper part at either end is the pump suction.
Pipe Coverings, see Insulating Materials.
Digiti
zed by G00gk
SECTION VII
ELECTRICITY
Ohm (R), the unit of resistance, is represented by the resistance
offered to an unvarying electric current by a column of mercury
14.452 grammes in mass, of a constant cross-sectional area, 106.3
cm. long, at a temperature of melting ice. It may be conceived as
about the resistance of the following lengths of copper wire of the
Brown and Sharpe gauge given.
94 ft. No. 20 B. and S. 380 ft. No. 14 B. and S.
124.4 19 605 12
150 18 961 10
239 16 1529 8
Amperes (C), the unit of current, is represented by the unvary-
ing current which when passed through a solution of nitrate of
silver (according to a specification adopted by the International
Congress of Electricians, Chicago, 111., 1893) in water deposits
silver at the rate of .001118 gramme per second.
Volt (E), the unit of electromotive force, is the electromotive
force that, steadily applied to a conductor whose resistance is one
ohm, will produce a current of one ampere.
Coulomb (Q), the unit of quantity, is the quantity of electricity
transferred by a current of one ampere in one second.
Farad, the unit of capacity, is the capacity of a conductor charged
to a potential of one volt by one coulomb of electricity.
Joule, the unit of work, is the energy expended in one second
by a current of one ampere against a resistance of one ohm.
Watt, the unit of power, is the work done at the rate of one joule
per second.
Henry, the unit of induction, is the induction in the circuit
when the electromotive force induced in the cj-cuit is one volt
CQ1
532 ELECTRICITY
while the inducing current varies at the rate of one ampere per
second.
Let C = current in amperes
E — electromotive force in volts
R = resistance in ohms
E
Then C = -^ (often called Ohm's Law)
Amperes X volts = watts
746 watts = 1 horse power
One watt = ,- '
746
1,000 watts = one kilowatt (lew.)
*1.34h. p.
2,654,200 ft.-lb. per hour
44,240 ft.-lb. per minute
One kilowatt = ■{ 737.3 ft.-lb. per second
3,412 heat units per hour
56.9 heat units per minute
.948 heat units per second
One megohm = 1,000,000 ohms
Voltage.— This is either 100-110 or 200-220 volts for steamers.
For the latter voltage the wiring is on the three-wire system, the
large motors being connected across the outers, and small motors
and lighting being connected between each outer and the middle
wire. In the low-pressure or voltage system there is less danger of
shock to passengers and crew, and less risk of fire and leakage.
In the high-pressure the cost of wiring is considerably reduced,
but the high pressure requires better insulation.
On war vessels 220 volts have proved very satisfactory. For
installations of 1,000 kw. and upwards, the higher pressure is
adopted from an economical standpoint. For motors, the high volt-
age can be chosen to advantage as a 220-volt machine is slightly
superior in efficiency to a 110, the size of commutator is reduced
in length, and the size of brushes is approximately halved. The
220-volt machines are, as a rule, smaller, lighter and cheaper.
Heaters can be run equally well off either voltage but lighting is
better off low owing to the lamps being stronger and cheaper.
Small motors up to say l/& h. p. are better suited for low voltage
owing to the difficulties in insulating and construction details for
high.
Digitized by LiOOQ LC
ELECTRIC INSTALLATIONS 533
The following table contains data on electric installations.
Ship
Owner
Generating Units
Voltage
CunardS. S. Co
Four 400 kw. turbogen-
erators, 1.500 r. p. m.
Four 375 kw. turbogen-
erators, 1,200 r. p. m.
220
3- wire
CunardS. S. Co
110
Britannic and Olympic .
White Star Line
Four 400 kw., 3-crank
compound inclosed en-
100
Alsatian and Calgarian
Allan S. S. Co
gines, 325 r. p. m.
Three 250 kw. turbo-gen-
220
erators at 3,000 r.p.m.
3- wire
Mis8anabie and Meta-
Canadian Pacific R.
Three 100 kw. turbogen-
100
gama
Co.
erators
Camito and Coronada . .
Elders & Fyffes
Three 90 kw., 2-crank
compound engines, 450
100
Eloby and Elele
Elder, Dempster Co .
Two 20 kw. , single-cylin-
der engines, 600 r. p. m.
100
Wires. — Copper is used more than any other material for trans-
mitting electricity. The size of a wire depends on the current it
has to carry, that is, on the number of amperes, while the insu-
lation depends more on the voltage. Conductors up to No. 8
B. & S. gauge may be of single wires, but above this size the neces-
sary conductivity should be obtained by conductors made up of
several small wires.
The wires should be well insulated by a material that is not
affected by salt water, and preferably should be run in conduits
instead of being fastened to the deck beams with cleats. All wires
should be kept out of coal bunkers if possible.
The unit of measurement in measuring the cross-sectional area
of a wire is the circular mil, which is the area of a circle one mil
(.001 inch) in diameter.
Lloyd's Rules state: "Except for wiring fittings the sectional
area of any copper conductor must not be less than No. 18 Stubs
wire gauge (S. W. G.). All copper conductors of a greater sec-
tional area than No. 14 S. W. G. must be stranded.
"The insulating material must be either vulcanized rubber of
the best quality or must be equally durable.
"The insulation must be such that when the cables have been
immersed in water for 24 hours it will, while still immersed, with-
stand 1,000 volts for half an hour between the conductors and the
water.
Digitized by VjOOQ LC
534
ELECTRICITY
"The insulating resistance should not be less than 600 megohms
per statute mile at 60° Fahr., after the cables have been immersed
in water for 24 hours, the test being made after one minute's elec-
trification at not less than 500 volts and while the cable is still im-
mersed."
Sizes of Wires
(Table from Lloyd's)
Number of
Wires and
Gauge
inS. W. G.
or in Inches
Nominal
Sectional
Area of
Conductors
in Square
Inches
Maximum
Current
Permissible
Amperes
Number of
Wires and
Gauge
in S. W. G.
or in Inches
Nominal
Sectional
Area of
Conductors
in Square
Inches
Maximum
Current
Permissible
Amperes
Is [3/25
If 3/24
S^ 13/23
.0009
3.7
19/17
.046
70.
.0011
4.5
7/.097'
.050
74.
.0013
5.3
19/.058'
.050
74.
1/18
.0018
7.2
19/16
.060
83.
3/22
.0018
7.2
19/15
.075
97.
7/25
.0022
8.6
19/14
.094
113.
3/21
.0024
9.5
19/.083'
.100
118.
1/17
.0025
9.8
37/16
.117
130. "
7/24
.0026
10.4
19/13
.125
134.
3/20
.0030
12.0
37/15
.150
152.
7/23
.0031
12.4
19/.101'
.150
152.
1/16
.0032
12.9
37/14
.182
172.
3/19
.0037
14.8
37/.0S3'
.200
184.
1/15
.0041
16.3
37/13
.250
214.
7/22
.0042
17.0
37/12
.300
240.
1/14
.0050
19.
37/.112'
.350
264.
3/18
.0053
20.
61/13
.400
288.
7/21
.0055
21.
61/.097"
.450
310.
7/20
.0070
24.
61/12
.500
332.
7/19
.0086
28.
61/.108*
.550
357.
7/18
.0125
34.
61/112
.600
384.
7/17
.017
40.
61/118
.650
410.
19/20
.019
43.
91/.098"
.700
434.
7/16
.022
46.
91/.101*
.750
461.
19/19
.023
47.
91/.108'
.800
488.
7/.06S'
.025
50.
91/.112'
.900
540.
7/15
.028
53.
91/.118'
1.000
595.
19/18
.034
59.
127/.101'
1.000
595.
7/14
.035
60.
The above sizes provide security against undesirable rise of temperature,
long leads larger wires will be required to prevent undue drop of voltage.
For
JvJ^VI^
CARRYING CAPACITIES OF WIRES
535
The following table (representing United States practice) showing
the allowable carrying capacity of copper wires and cables of 98%
conductivity, according to the standard adopted by the American
Institute of Electrical Engineers, should be followed.
Allowable Carrying Capacities op Wires
B. & S. Gauge Number
Diameter of Solid Wire
in Mils
Area in Circular Mils
18
40.3
1,624
16
50.8
2,583
14
64.1
4,107
12
80.8
6,530
10
101.9
10,380
8
128.5
16,510
6
162.0
26,250
5
181.9
33,100
4
204.3
41,740
3
229.4
52,630
2
257.6
66,370
1
289.3
83,690
0
325
105,500
00
364.8
133,100
000
409.6
167,800
200,000
0000
460
211,600
300,000
400,000
500,000
600,000
700,000
800,000
900,000
1,000,000
1,100,000
1,200,000
1,300,000
1,400,000
1,500,000
1,600,000
1,700,000
1,800,000
1,900,000
2,000,000
The volt loss in a given length is directly proportional to the
transmitted current.
Digiti
zed by G00gk
536
ELECTRICITY
The distance that a wire will transmit a current with a certain
volt loss is inversely proportional to the current.
In the table below (from Standard Wiring, J. J. Cushing), the
column headed Feet per Volt Ampere gives the number of feet that
the adjacent size of wire will transmit one ampere with a loss of
one volt; this is a constant quantity for each size of wire.
Wiring Table for Direct Current
Siae of Wire
B. & S. Gauge
Feet per Volt Ampere
0000
10068.4
000
7998.7
00
6339.5
0
6025.1
1
3974.5
2
3166.5
3
2495.0
4
1980.0
5
1347.0
6
1248.7
7
986.7
8
779.6
9 -
$18.4
10
495.0
11
394.0
12
312.3
13
246.7
14
194.0
If it is desired to know how far a given wire will transmit a
given current at a certain line loss, select from the second column
opposite the size of the wire constant in the Feet per Volt Ampere
column and multiply this figure by the desired loss and divide by
the current to be transmitted.
To find how much current can be transmitted a given distance
with a certain line loss, multiply this constant by the line loss
and divide by the distance.
If it is desired to know the line loss that will occur when trans-
mitting a certain current through a given size of wire, multiply
the distance and current together and divide by the constant for
the size of wire which it is desired to use.
Digitized
by Google
COPPER WIRE
537
Copper Wire Table
Resistance per Mil-Foot 10.4 Ohms at 75° F. (24° C).
Temperature coefficient + .0021 per degree F.
Specific Gravity 8.9. Weight per cubic inch 0.321 lb.
Area in
Resistance
Brown
Diameter
in Inches
Circular
Mils.
Feet
per Lb.
& Sharpe
c. m. = D»
Ohms per Lb.
Ohms per Ft.
1
0.2893
83,690.
3.947
0.0004883
0.0001237
2
0.2576
66,370.
4.977
0.0007765
0.0001560
3
0.2294
52,630.
6.276
0.001235
0.0001967
4
0.2043
41,740.
7.914
0.001963
0.0002480
5
0.1819
33,100.
9.980
0.003122
0.0003128
6
0.1620
26,250.
12.58
0.004963
0.0003944
7
0.1443
20,820.
15.87
0.007892
0.0004973
8
0.1285
16,510.
20.01
0.01255
0.0006271
9
0.1144
13,090.
25.23
0.01995
0.0007908
10
0.1019
10,380.
31.82
0.03173
0.0009972
11
0.09074
8,234.
40.12
0.05045
0.001257
12
0.08081
6,530.
50.59
0.08022
0.001586
13
0.07196
5,178.
63.79
0.1276
0.001999
14
0.06408
4,107.
80.44
0.2028
0.002521
15
0.05707
3,257.
101.4
0.3225
0.003179
16
0.05082
2,583.
127.9
0.5128
0.004009
17
0.04526
2,048.
161.3
0.8153
0.005055
18
0.04030
1,624.
203.4
1.296
0.006374
19
0.03589
1,288.
256.5
2.061
0.008038
20
0.03196
1,022.
323.4 •
3.278
0.01014
21
0.02846
810.1
407.8
5.212
0.01278
22
0.02535
642.4
514.2
8.287
0.01612
23
0.02257
509.5
648.4
13.18
0.02032
24
0.02010
404.0
817.6
20.95
0.02563
25
0.01790
320.4
1,031.
33.32
0.03231
26
0.01594
254.1
1,300.
52.97
0.04075
27
0.0142
201.5
1,639.
84.23
0.05138
28
0.01264
159.8
2,067.
133.9
0.06479
29
0.01126
126.7
2,607.
213.0
0.08170
30
0.01003
100.5
3,287.
338.6
0.1030
31
0.008928
79.70
4,145.
538.4
0.1299
32
0.007950
63.21
5,227.
856.2
0.1638
33
0.007080
50.13
6,591.
1,361.
0.2066
34
0.006305
39.75
8,311.
2,165.
0.2605
35
0.005615
31.52
10,480.
3,441.
0.3284
36
0.0050
25.0
13,210.
5,473.
0.4142
37
0.004453
19.83
16,660.
8,702.
0.5222
38
0.003965
15.72
21,010.
13,870.
0.6585
39
0.003531
12.47
26,500.
22,000.
0.8304
40
0.003145
9.888
33,410.
34,980.
1.047
Digiti
zed by G00gk
538
ELECTRICITY
Diameters by Different Wire Gauges
See also Sect. 3
Diameters in Mils. 1 Mil. - 0.001 Inch
Gauge Number
Brown & Sharpe
Birmingham
British Imperial
0000
460
454
400
000
410
425
372
00
365
380
348
0
325
340
324
1
289
300
300
2
258
284
276
3
229
259
252
4
204
238
232
5
182
220
212
6
162
203
192
7
144
180
176
8
128
165
160
9
114
148
144
10
102
134
128
11
91
120
116
12
81
109
104
13
72
95
92
14
64
83
80
15
57
72
72
16
51
65
64
17
45
58
56
18
40
49
48
19
36
42
40
20
32
35
36
21
28.5
32
32
22
25.3
28
28
23
22.6
25
24
24
20.1
22
22
25
17.9
20
20
26
15.9
18
18
27
14.2
16
16.4
28
12.6
14
14.8
29
11.3
13
13.6
30
10.0
12
12.4
Digiti
zed by G00gk
WIRING SYSTEMS 536
Examples. How far will a No. G wire transmit 20 amperes with a line loss of
15 volts? The constant (see table) for No. 6 wire is 1,248.7, multiply this by the
line loss of 15 volts, which gives 18,730 . 5, and dividing this product by 20 amperes,
the quotient is 930 . 5, which is the required distance in feet.
Suppose a current of 20 amperes is to be transmitted 93G.5 feet, what will be
the line loss, if No. 6 wire is used? Multiply the distance of 936.5 ft. by the
current to be transmitted, viz. 20 amperes, which gives a product of 18,730. Divide
this by the constant for No. 6 wire, which is given in the table as 1,248.7, and the
quotient is 14 . 999; that is, the line loss is practically 15 volts.
In a distance of 930 . 5 ft. the conditions are such that a line loss of 15 volts must
not be exceeded. How many amperes can be transmitted with a No. 6 wire?
Multiply the constant of No. 6 wire, 1,248.7, by the line loss of 15 volts, giving
18,730.5, and dividing this by the distance 963.5 ft., the quotient of 20 amperes
is obtained.
Assume that the resistance per mil-foot for copper is 10.4, which
is a fair average, then
10.4 X feet X 2 X amperes
volts lost
Circular mils
Tr .. . A 10.4 X feet X 2 X amperes
Volts lost = : j n
circular mils
__ circular mils X volts lost
Amperes - feet x 2 x 1Q 4
In the above, feet refers to the actual length of the circuit and
is multiplied by 2 to obtain the total length of wire.
Size of wire for motor circuits.
Let D = length of motor circuit from fuse block to motor
E — voltage at the motor
L — drop in percentage of the voltage at the motor,
which in marine installations is small, say 3%
K — efficiency of the motor expressed as a decimal. The
average values of K are about as follows: one h. p.
= .75; 3 h. p. - .80; 10 h. p. and over = .90.
21 .6 = ohms per foot run in circuit where wires are one mil
in diameter
746 watts = one h. p.
H. p. = horse power of motor
mu 4U . , ., h. p. X 746 X D X 21.6
Then the circular mils = — — e X L X K
Wiring Systems. — The wiring may be either on the two-wire or
three-wire system (see Fig. 90), the former being more common
Digitized by VjiOOQ 1C
540
ELECTRICITY
w/fc/? £&arcf
/^crrcr/Ze/ W/r/n?
Z
6 — Q
o
O — 6
Ser/es k//r/r?<?
r/?ree h//r& System
Figure 90. — Wiring Diagrams.
Digiti
zed by G00gk
CONDUITS 641
than the latter. In general, in the three-wire system the lighting
and small motors not exceeding 3^ h. p. are connected between the
outers and the middle wire as near as may be practicable, to equalize
the load on each outer and keep low the out-of-balance current;
this also applies to small heaters. Large motors are supplied from
the outers as well as large heaters.
In some steamers two dynamos are run together on the three-
wire system. Here the positive wires of one dynamo are connected
to the negative wires of the other dynamo, and from this point is a
central or neutral wire that serves as a common return for both. The
voltage is usually 220, but as this is divided between the two, the
working voltage for the circuits is 110. The lamps are arranged
so that they are equally divided between the two outside wires
and the center one, to balance each other and divide the current.
If the same number of lamps are run on each side, the middle wire
will carry no current, but should more lamps be switched in on one
side than on the other, the difference of current resulting will then
be carried by the central wire. All three wires are of the same size.
In the three-wire system the main switches and cut-outs are of the
three-pole type.
The following notes are on the wiring of U. S. battleships, the
latest types of which are wired on the three-wire system. "Twin
conductors on all circuits of 60,000 circular mils cross section or
less, and all branches on lighting circuits for single lights shall be
of 4,170 circular mils cross section twin conductor. The wiring is
designed on a basis of maximum allowable drop of not over 2%%
for lighting circuits, calculated from adjacent dynamo room and
3% from distant dynamo room, and 5% for power and circuit
(including heating and cooking circuits) calculated from adjacent
dynamo room, and 6% from distant dynamo room, the drop to be
reckoned from the bus bars on generator switchboard. The speci-
fied drops for power circuits are calculated on the basis of full
battle load; for lighting circuit the full cruising load forms the
basis. The wiring for lighting system is calculated on a basis of
one-half ampere for each 16 candle power lamp."
Conduits. — These may be of steel enameled, brass enameled
and flexible rubber-lined hose. The steel and brass enameled
conform in their metal parts to the dimensions for standard steam,
gas and water pipes. The fittings for steel enameled conduit are
of malleable or cast iron, and for brass enameled, brass or the
beaded malleable pattern.
Digitized by LiOOQ IC
542
ELECTRICITY
Standard Size of Conduits for the Installation of Wires
and Cables
As adopted and recommended by The National Electrical Con-
tractors' Association of the United States.
Conduit sizes based on the use of not more than three 90° elbows
in runs taking up to and including No. 10 wires; and two elbows
for wires larger than No. 10. Wire No. 8 and larger are stranded.
Number of Wires in System
Duplex Wire
Size
B.&S.
Capacity
Amperes
One Wire in a
Two Wires in a
Three Wires in a
Four Wires in a
Conduit. Size
Conduit. Size
Conduit. Size
Conduit. Size
Conduit, Ins.
Conduit, Ins.
Conduit, Ins.
Conduit, Ins.
Inter'l
ExterM
Inter'l
Exter'l
Inter'l
Exter'l
Inter'l
Exter'l
14
15
lA
.84
A
.84
H
.84
Yx
1.05
12
20
Vi
.84
%
1.05
Yx
1.05
Y<
1.05
10
25
A
.84
Yx
1.05
X
1.05
1
1.31
8
35
A
.84
1
1.31
1
1.31
1
1.31
6
50
A
.84
1
1.31
V/i
1.66
H!
1.66
5
55
Yx
1.05
V/x
VA
1.66
V/i
1.66
1.66
4
70
Yx
1.05
1.66
V/x
1.66
Vi
1.9
3
80
Yx
1.05
vl
1.66
V/x
1.66
VA
1.9
2
90
Yx
1.05
v\
1.66
va
1.9
VA
1.9
1
100
Yx
1.05
VA
1.9
\A
1.9
2
2.37
0
125
1
1.31
VA
1.9
2
2.37
2
2.37
00
150
l
1.31
2
2.37
2
2.37
VA
2.87
000
175
l
1.31
2
2.37
2
2.37
2H
2.87
0000
225
VA
1.66
2
2.37
VA
2.87
VA
2.87
CM.
250000
237
V/x
1.66
VA
VA
2.87
VA
2.87
3
3.5
300000
275
Vi
1.66
2.87
VA
2.87
3
3.5
400000
325
Vi
1.66
3
3.5
3
3.5
VA
4.
500000
400
VA
1.9
3
3.5
3
3.5
VA
4.
600000
450
VA
1.9
3
3.5
VA
4.
700000
500
2
2.37
VA
4.
VA
4.
800000
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VA
4.
4
4.5
900000
600
2
2.37
4.
4
4.5
1000000
650
2
2.37
4
4.5
4
4.5
1250000
750
VA
2.87
4H
4.5
4*4
5.
1500000
850
2A
2.87
4^
5.
5
5.56
1750000
950
3
3.5
5
5.56
5
5.56
2000000
1050
3
3.5
5
5.56
6
6.62
14
15
A
.84
Yx
1.05
1
1.31
1
1.31
12
20
Vi
.84
Yx
1.05
1
1.31
VA
1.66
10
25
Yx
1.05
1
1.31.
V/x
1.66
VA
1.66
Exam-pie. To ascertain the size of conduit for three No. 4-0 wire, follow down
the wire column to No. 1-0 and then across to the section headed "Three wires
in a conduit" and it will be seen that 2 H -inch conduit is the size to use and that
the external diameter is 2.87 inches.
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SWITCHBOARDS 643
Switchboards. — Switchboards have their panels of marble or
slate firmly supported by a substantial frame fastened to the deck.
They should be about 2 ft. away from any bulkhead so that access
can be had to the back of the board. The size depends on the elec-
tric equipment of the vessel, and as to location the main switch-
board should be in the same compartment as the generators. The
following is a list of instruments and apparatus found on most
boards:
Main switch, the connecting link through which the current
must pass from the generator to the distributing system.
Ammeter, an instrument indicating the output of the plant
in amperes.
Voltmeter, an instrument indicating the voltage of a circuit.
Wattmeter, an instrument for measuring electrical power, in-
dicating in watts.
Field Rheostat, a resistance device, usually adjustable, placed in
series with the generator field windings for regulating the voltage
of the generator.
Fuse, a device designed to melt at a predetermined current,
and to protect apparatus against abnormal conditions of current.
Fuses are rated at 80% of their capacity so that an overload of 25%
will cause them to burn out.
Ground detector, consisting of two lamps for giving the operator
a warning signal when a wire is grounded.
Instrument lamps, for lighting the board.
An automatic circuit breaker may also be installed, which is a
device for automatically opening a circuit when the current exceeds
the maximum amount desired. There are two kinds of circuit
breakers, depending on the method employed for rupturing the
arc; in the magnetic blow-out the arc is extinguished by a strong
magnetic field, while in the carbon break the arc is ruptured at a
secondary set of carbon contacts which may be easily renewed.
See also abstracts from Lloyd's Rules on page 549, and General
Notes, page 544.
Determination of Output. — The usual way of determining output
for installations up to 100 kw. is to add together the power required
for all the motors on full load, fighting, heating, wireless, etc.,
plus 10 to 15% for future additions. One or nore units of the capac-
ity thus obtained is installed according to the day load and the
desired degree of security against breakdown. The capacity of
large main generating plants may be settled from the probable
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544 ELECTRICITY
day load curve, a set being of sufficient capacity to deal with the
load for the lighter part of the day and supplemented by one or more
sets during the heavier part.
Although engine sets cost less and have a slightly less steam
consumption when new than turbo sets, there are many advantages
in favor of the latter, as less space is required, and the foundations
for them need not be so heavy as the weight is less.
As to the rating of turbogenerators: The most economical
output of the turbine (i. e., the output at which it attains its max-
imum steam economy) should not correspond with the generator
rating in kilowatts except under special circumstances. In general,
it will be found preferable, when ordering a combined set, to specify
that the most economical output of the turbine shall be equal to
80% of the kilowatt rating of the generator as defined in these
Rules, i. e., equal to 80% of the maximum continuous output of
the generator in kw. The average output of the alternator is usu-
ally something between three-quarters of the rated output, and the
rated output and the average output of the combined set should
clearly be the most economical output for the prime mover. It
should further be stated that for mechanical reasons the steam inlets
should be capable of by-pass or otherwise of dealing continuously
with outputs of 12% in excess of the rated output which is 40%
in excess of the economical output as defined above. (From Re-
port No. 72, Engineering Standards Committee, British.)
GENERAL NOTES FOR LAYING OUT ELECTRIC INSTALLA-
TIONS
Before laying out an installation the following notes should be
read over. They are from the National Electrical Code of the
National Board of Fire Underwriters of New York. A list of
inspected electrical appliances published by the Underwriters'
Laboratories, New York (under the direction of National Board of
Fire Underwriters), can often be consulted to advantage for informa-
tion relative to electrical materials and devices which have been
tested and found to comply with standard requirements.
"Generators. — a. Must be located in a dry place and provided with
protecting hand rails.
b. Must be provided with a name plate giving the maker's
name, the capacity in volts, amperes and kilowatts, the nor-
mal speed in revolutions per minute, and whether shunt, series
or compound.
Digiti
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WIRES 545
c. Generators of storage batteries employed for auxiliary
(emergency) lighting or power must be located as far above
the load water line as practicable.
"Wires. — a. Must, except around generators, at switchboards and
in wire tunnels, be enclosed in approved metal conduits unless
covered with approved metal armor or metallic braid.
b. All conductors larger than No. 12 B. & S. gauge must be
stranded. Except in fixture wiring no single conductor smaller
than No. 14 B. & S. gauge shall be employed.
c. Except at fixtures, conductors must not be spliced unless
special permission in writing is given in advance.
d. Except at fixtures, and as provided in the preceding para-
graph, splices and taps shall be made by means of approved
connection blocks enclosed in approved fittings. Those
fittings shall be located in readily accessible places and will
not be permitted in bunkers.
e. Must be led through metallic stuffing tubes where passing
through watertight bulkheads and through all decks, deck
tubes being extended to a height of 18 ins. above the surface
of the deck.
f. Must not be drawn in until all mechanical work on the
vessel has been, as far as possible, completed. Pull boxes
shall be installed at sufficient intervals to permit of the draw-
ing in of conditctors without undue strain. These pull boxes
shall be provided with gasketed watertight covers, the length
of the opening in the box to be at least ten times the diameter
of the largest conductor contained therein.
g. Must when closed in metal molding, flexible metal con-
duit, metal armor or metallic braid be provided with addi-
tional mechanical protection where passing through coal
bunkers and where otherwise exposed to severe mechanical
injury.
h. Where metallic braid cable passes through beams or
non- watertight bulkheads it must be protected from abrasion.
All sharp bends in such cable must be avoided.
"Portable Conductors. — Must be made of two or more stranded
conductors, each having a carrying capacity equivalent to
No. 14 B. & S. gauge or larger and each provided with an
approved insulation and covering.
•
546 ELECTRICITY
"Bell or other Signaling Wires. — a. Must be of not less than No.
16 B. & S. gauge and must not be run in the same conduit,
molding or armor with light or power wires.
b. Where radio systems are employed, all permanent wiring
in the radio room and above the top metal deck must be mag-
netically shielded. Any protection placed around antennae
leads to prevent ready access to same must be of metal, per-
manently and effectually grounded.
c. It is strongly recommended that all metal work above
the top metal deck be permanently and effectually grounded.
"Switchboards. — a. Must be made of approved non-combustible
non-absorptive insulating material.
b. Must be kept free from moisture and so located as to
be accessible from all sides.
c. Must have a main switch, automatic cut-out, and am-
meter for each generator and at least one voltmeter and one
ground detector.
d. Each circuit leading from the board must be protected
by a cut-out and controlled by a switch.
"Cut-outs and Switches. — a. Must, except on switchboards and in
living spaces, be enclosed in moisture proof cases. Must be
arranged to break all poles of the circuit and must not be
located in bunkers or other inaccessible places.
b. Must be so arranged that each freight compartment
may be separately protected and controlled
c. Must be enclosed in metal cabinets when located else-
where than on switchboards.
d. Must, except for motors, searchlights and diving lamps
be so placed that no group of lamps or other current consuming
devices requiring more than 660 watts shall be dependent
upon one cut-out.
"Removable Fittings. — In vessels having any space allotted alter-
nately to passengers and cargo, the fixtures and wiring in
such space shall be so designed as to be removable and the
points of disconnection so arranged that they can be properly
insulated and covered up. Main fuses and switches shall
not be located within these spaces.
"Signal Lights. — a Must be provided with approved telltale board
located preferably in pilot Tiouse which will immediately indi-
cate a burned out lamp. Each side of all signal circuits shall
be carried through the telltale board and fused at this point.
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MOTORS 547
b. Signal circuits shall in no case supply other than signal
lights.
"Motors. — Must each be provided with a name plato giving the '
maker's name, the capacity in volts, amperes and kilowatts,
and the normal speed in revolutions per minute."
Distributing Systems.* — These may be divided into lighting and
motor circuits. In the former, feeders are led from the switch-
board to distribution cabinets and branch leads are then distributed
to groups of lamps, not more than 660 watts being assigned to one
branch line. The usual allowable voltage drop to the farthest
outlet is 3%.
Motor Circuits. — Feeders are led direct from the main switch-
board to a double-pole switch and cut-out placed in the line to
protect the starting box and motor. The cut-out switch and
double-pole switch are not necessary for motors of x/i h. p. or less.
There is briefly outlined, below, the circuits a steamer of about
400 ft. long might be divided into. Directly following this section
is one on Motor Boat Circuits and abstracts from Lloyd's Rules.
Positive wires or terminals are marked + and painted red, while
negative are marked — and painted black.
(1) Machinery space circuit, which includes the main engine
room, refrigerating engine room, boiler rooms, forced draught fan
rooms, and the shaft tunnels.
(2) Navigating circuit, which includes the ship's signal lamps,
viz., foremast head, mainmast head, side and stern lights, also
the lights fitted to telegraphs, compasses, and other instruments
to illuminate the dials at night, and the Ardois signals.
(3) Cargo light circuit, which includes the portable arc lamps
and the fixed lights in the holds, which are only lighted when the
ship is being loaded or -unloaded.
(4) Starboard saloon circuit, which takes in the principal saloons
and staterooms on the starboard side.
(5) Port saloon circuit, similar to the starboard.
(6) Forward circuit, which usually includes the crew's quarters
and the third-class passenger accommodations.
(7) The amidship circuit, which serves the lower central portion
of the ship, including officers' and engineers' rooms, stores, galleys,
etc.
(8) After circuit, taking in the after accommodation, usually
occupied by second-class passengers and ship stewards.
♦Abstracts from Ship Wiring and Fitting, T. M Johnson.
1
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548 ELECTRICITY
(9) Miscellaneous circuit, for ventilating fans, galley and laundry
machinery.
It is not necessary for all the circuits to be controlled by sepa-
rate switches on the main board. For instance, the circuits just
enumerated could be combined into say four main circuits thus:
(A) forward, (B) amidships, (C) after, and (D) machinery space.
If this arrangement were adopted, separate auxiliary switchboards
would then be fitted in the four sections of the ship referred to.
The sections would be split up into separate individual circuits
controlled from the auxiliary boards.
(1) Machinery Space Circuit. — Here the main cables are run from
the main switchboard to the section board, and from this section
board cables are run to three distribution boards located as follows :
Distribution board la is in the stokehold for supplying lamps
there, also for those in the passages between the boilers, lamps in
fan rooms, portable lamps and clusters in the bunkers.
Distribution board 2a would be in the forward end of the main
engine room, and would supply about half of the engine room lights,
that is, those at the forward end.
Distribution board 3a would be at the after end of the engine
room and would supply the remainder of the engine room lights
and also those in the shaft tunnel.
It is impossible to give a definite figure for the number of lights
required, owing to the variation in the sizes and shapes of ma-
chinery spaces on different ships, but on an average a fairly good
light can be obtained by arranging 8 candle power lamps about 8
ft. apart.
(2) Navigating Light Circuit. — Here the main cables are run
from the main switchboard to the chart house. From the board in
the chart house are wires to the regulation lights, viz., foremast
hea{J, mainmast head, port and starboard side lights, and stern
light, also lights to engine and docking telegraphs, steering and
standard compasses and Ardois lights.
(3) Cargo Light Circuit. — The distribution boards to which the
cables from the main switchboard run are generally located on
the deck above. When the engines and boilers are amidships there
are two boards, one for the forward cargo hold and the other for
the after. In this circuit are often clusters of incandescent lamps
or one or more arc lamps.
(4) and (5) Starboard and Port Saloon Circuits are very much
alike, the cables from the main switchboard going to a distribut-
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FORWARD CIRCUIT 649
ing board on the starboard side and to another board on the port
side.
(6) Forward Circuit. — Here the cables from the main board run
to a board forward. From the latter is the circuit for lighting the
various compartments.
(7) Amidship Circuit. — From the distribution board will be
circuits for both light and power. Invariably small motors will
be installed for running laundry machinery, and other machinery
in the galley.
(8) After Circuit. — Similar to the forward.
(9) General Motor Circuit. — This is required on large vessels
where the ventilating fans are driven by electric motors, and there
are installed electric elevators and other special machinery re-
quiring motors.
The method adopted for distributing electricity depends on the
purpose for which it is to be used. For incandescent lamps and
motors the parallel distribution is invariably adopted, as shown
in Fig. 90. /Here each lamp has its own bridge across the mains
and can be turned on and off independently of the others.
Note the following abstracts from Lloyd's Rules: "The main
switchboard should be fitted if possible in the dynamo room, to
which all the main circuits throughout the ship should be brought,
a switch and fuse being fitted thereon for each circuit. The auxiliary
switchboards for further subdivision of the current should be placed
in conveniently accessible positions, and each such switchboard
should be similarly fitted with a separate switch and fuse for each
sub-circuit. Fuses should be fitted to each lamp circuit when
these are made with reduced size of wire. If vessels are wired
on the double-wire system (this is invariably the case) fuses should
be fitted to each cable of these circuits.
"The switchboards should be of slate or other incombustible
non-conducting and moisture proof material. The switches should
be on the quick-break principle and be so constructed that they
must be either full on or off, that is, they must not remain in an
intermediate position.
"Fuses should be fitted to each main or auxiliary circuit on
the switchboards, as near as possible to the switches of these cir-
cuits. If the switchboard is not near the dynamo or if more than
one dynamo is used on any one circuit, then fuses should also be
fitted to the main cable as near as possible to each of the dynamo
terminals. They should be mounted on slate or other incombus-
19
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550 ELECTRICITY
tible bases and be arranged so that the fused metal may not be a
source of danger and where they are fitted with covers these should
be incombustible.
"All fuses should be of easily fusible and non-oxidizable metal,
and be so proportioned as to melt with a current 100% in excess
of that which the cables they protect are capable of carrying as
shown in table of Sizes of Wires, page 536. The terminals must
be spaced apart or screened, so that an arc cannot be maintained
when the fuse is blown. Separate single fuses and not double-pole
fuses must be used on circuits where the voltage exceeds 125 volts.
"In shaft passages and in damp places, all lamp switches and
fuses should be of a strong watertight pattern, or should be placed
in watertight boxes having hinged or portable watertight covers.
No switches or cut-outs are to be placed in bunkers.
"There should be no joints in the cables leading from the dynamo
to the main switchboard, nor in those leading from the main to the
auxiliary switchboards, nor should branches to single lamps be
taken off these cables. v
"The position and type of dynamos and electric motors should
be such that the compasses will not be affected. Dynamos and
large motors should be at least 30 ft. from the standard compass."
Wiring of Motor Boats. — The wiring of motor boats is com-
paratively simple compared to that of steamers. For example,
take the wiring of a 45-footer. An engine for a boat of this size
would be say electric started, the motor serving as a generator after
the engine was under way, charging a set of storage batteries. These
batteries, by means of suitable connections at the switchboard,
would be used for lighting. Where the wiring is supported on
cleats, they should be spaced about 4 ft. 6 ins. apart. Preferably
the wires should be run in moldings, and when liable to injury
should be in conduits.
The lighting circuit of a motor boat say from 30 to 50 ft. long,
may be one of 6 volts, but for larger craft where there is room
for the installation of a direct connected gasoline engine and gen-
erator the voltage may be 110, for this voltage is better adapted
for electric motors, and cooking and heating devices.
As a 45-ft. motor boat would have no occasion to require electric
motors, except perhaps small ventilating fans that could be at-
tached to lamp sockets, there would be only one distributing circuit
from the switchboard and that would be for lighting. The parallel
system would be adopted, on which would be the running lights and
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GASOLINE ENGINES 551
also those to the staterooms. The boat can be well lighted by twelve
4 c. p. Mazda lamps (see page 552). The running lights and the
anchor light would each contain a 6 c. p. lamp, the binnacle light a
2 c. p. and the searchlight a 20 c. p., thus making a total of 100 c. p.
The efficiency of a 6-volt Mazda lamp is about 1 % watts per c. p.,
therefore the total electric energy consumed would be 125 watts,
which at 6 volte would mean a current of approximately 21 amperes.
As not more than 60% of the lamps would be in use at one time,
this would call for a current of 13 amperes. Hence a storage
battery with a capacity of 100 ampere hours would run the lamps
continuously for say 8 hours. For a larger boat, the lamps would
be 8 or 16 c. p. Above arrangement from bulletin issued by
General Electric Co.
. Wiring of Gasoline Engines. — As mentioned in the section on
internal combustion engines, there are two systems of electric igni-
tion, viz., the jump spark (Fig. 84) and the make and break (Fig. 85).
The former as applied to a single-cy Under engine is as follows:
Starting from the battery, the current goes to a switch thrown to
connect with a spark coil, then to a spark plug in cylinder head, with
a return connection from the engine to the battery. There is also a
connection between the timer (which controls the time of the sparks)
and the spark coil. Should it be desired to use a magneto for igni- .
tion purposes, then the switch mentioned above would be thrown,
cutting out the batteries, and the current generated by the. mag-
neto (driven by the engine) would go to the spark coil, thence to
the spark plug as before with a return wire connection from the en-
gine to the magneto. If the engine has two cylinders there would
be two spark coils, one for each, making two connections to the
timer, one for each cylinder; otherwise the wiring is the same.
A make and break system for a single-cylinder motor is as fol-
lows: Starting from the battery, then the switch, coil, and wire
to make-and-break connection on the side of the cylinder, with a
return wire to the battery. If a magneto is installed, throw switch
to start on the battery, and when the motor is running, throw
switch on magneto circuit which consists of a wire from magneto
to coil, thence to make-and-break connection with return to mag-
neto. If the motor has one or more cylinders, the connections to
the make-and-break devices would be made by branches from the
same main wire from the coil.
In both the jump spark and make-and-break systems, when the
motor is running on the magneto the battery is cut out.
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552
ELECTRICITY
Incandescent Lamps and Searchlights. — Common sizes of incan-
descent lamps are 8 and 16 c. p. of 110 volts. A 16 c. p. of 110
volts requires Yi ampere of current, calling for approximately 55
watts. Roughly, 10 such lamps can be operated per 1 h. p. at the
engine. Arc lamps are seldom installed on a ship, and when they
are, are wired in series. These lamps require 50 to 60 volts and a
current of 50 to 150 amperes, corresponding from 5 to 12 h. p. at
the engine.
The efficiency expressed in watts per candle power is the quotient
obtained by dividing the watts consumed by a lamp by the candle
Incandescent Lamps
(Direct Current)
Carbon
Volts
Candle power
Watts .
Amperes
110
2
10
.191
110
4.8
20
.182
110
8.1
25
.227
110
9.3
30
.273
110
16.8 ,
50
.455
110
20.2
60
.546
Gem Lamps
110
5
20
.1818
110
10.
30
.2727
110
15.6
40
.364
110
20.
50
.455
110
24.
60
.546
110
32.
80
1.727
110
40.7
100
1.909
Mazda (Tungsten)
110
7.1
10
.0909
110
11.5
15
.1363
110
16.
20
.1818
110
21.4
25
.228
HO
34.2
40
.364
110
53.6
60
.546
110
92.6
100
.909
110
146.0 .
150
1.364
y Google
SEARCHLIGHTS 653
power it gives. The lower the watts per candle power the higher
the efficiency. For example, 1.10 watts per candle power is a higher
efficiency than 1.17 watts.
Besides the ordinary incandescent lamp with a carbon filament
as above, there are manufactured (General Electric Co., New
York) one known as the Gem with a metallized carbon filament,
and another, the Mazda, with a filament of tungsten wire which
instead of being in vacuum is surrounded by an inert gas at a pres-
sure of about one atmosphere. Both the Gem and Mazda are
more efficient than ordinary carbon filament lamps.
Searchlights for motor boats and other small craft consist of a
high-powered incandescent lamp placed in front of a reflecting
mirror. In boats having no electric equipment other than a 6-volt
storage battery for ignition and a minimum amount of lighting
with low voltage, incandescent searchlights can be supplied (Gen-
eral Electric Co., New York) 6 to 10 ins. in diameter, the current
required being around 4 amperes.
For steamers and war vessels a powerful light is necessary and
this is obtained by carbon arcs. As to the effective range one
maker (Carlisle & Finch, Cincinnati, O.) states that on perfectly
clear dark nights their 7-inch projector will illuminate objects at
about Yl mile, the 9-inch }/% to % of a mile, the 14-inch 1 to 1J^
miles, the 19-inch 1J^ to 2 miles, the 24-inch 3 miles, the 32- inch
4 miles, and the 38-inch 5 miles. Under the most favorable condi-
tions the range may exceed the distances given.
There are three types of control: (1) the local hand control;
(2) the distant mechanical, in which the operator controls the
searchlight from below (or from one side or rear if preferred) by
means of hand wheels, gears and shafting; and (3) the distant electric,
where the searchlight is moved by electric motors, the controller
being at any convenient distance from the searchlight. Both
(1) and (2) may be hand controlled if desired.
In the Argentine battleship Moreno of 27,566 tons displace-
ment and 594 ft. long, there were 12 motor-operated, remote, elec-
trically controlled 110 cm. searchlights and one portable signaling
projector of 35 cm., all supplied with current of 110 volts. For
quickly changing from a dispersed to a closed beam of light there
was a double disperser consisting of two parallel systems of plano-
convex cylindrical lenses that could be drawn together or separated.
A complete horizontal cycle of a searchlight could be made in 28
seconds, or in 15 minutes, if desired, by the electric remote control.
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554
ELECTRICITY
Seakchlights
Diam-
eter of
Shell
Inches
Diam-
eter of
Reflec-
tor
Inches
Candle
Power
Cur-
rent
Am-
peres
Range
Miles
Height
Over all
Inches
Height
Center
of
Mirror
Width
Over all
Inches
Length
Over all
Inches
Net
Wt.
Lb.
9
10
15
20
8
13
19
1200
2000
4000
7000
6
10
20
35
V2
1
2
24
42K
44
51H
17«
35^
33^
39
10M
24%
UK
13M
16K
24
25
85
115
250
Engberg El. Co., St. Joseph, Mich.
Searchlights
Effective Dia. of
Mirror. Ins.
24
30
36
48
60
Current in
Amperes
45-50
80-90
110-120
140-150
180-200
Carlisle and Finch, Cincinnati, Ohio.
Batteries. — In a primary battery or cell, chemical energy is
transformed direct into electrical energy. Such a battery consists
essentially of two metallic conductors or poles dipping into an
electrolyte. Copper or carbon is commonly employed for the posi-
tive pole and zinc for the negative. The electrolyte may be sul-
phuric or nitric acid or sal ammoniac, caustic soda, or other salt.
There are two types of primary batteries, viz., wet and dry.
An example of the former is the Daniels, which has a voltage of 1.07
to 1.14 and an internal resistance of .3 ohm. For marine pur-
poses the dry has many advantages over the wet. In a dry battery
the negative pole, which also serves as a container, is a hollow zinc
cylinder, a common size being 6 ins. high by 2}4 ins. diameter.
The positive pole is a carbon rod, and the electrolyte is sal ammoniac
and zinc chloride. In new cells the electromotive force is between
1.5 and 1.6 volts, and the internal resistance .1 ohm which may
be increased to .5 ohm. Dry batteries are extensively used for igni-
tion purposes in gasoline engines.
Storage Battery. — A secondary or storage battery is one which
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NORMAL CAPACITY 655
can be regenerated after exhaustion by passing a current through
it in a direction opposite to the direction of current flow when
the battery is delivering current to a circuit.
There are two types; the lead, and the alkaline or Edison. In
the former the active material on both the positive and negative
plates is applied in the form of a paste to a stiff lead-antimony
alloy supporting grid, and the electrolyte is a dilute solution of
sulphuric acid. The specific gravity of the electrolyte when the
battery is fully charged varies from about 1.210 for stationary
batteries to about 1.300 for automobile and motor boat ignition
batteries. The voltage when being charged is from 2. to 2.5 volts,
and when being discharged it decreases from 2. to 1.7 volts.
The normal capacity of a storage cell is usually expressed in
ampere-hours at the 8-hour rate at 70° F. down to a certain voltage
per cell. For instance, when it is said that a cell has a capacity
of 100 ampere-hours it is usually meant that this cell can be dis-
charged at a rate of 12 J^ amperes continuously for 8 hours at
70° F., down to the limiting voltage specified by the battery manu-
facturer. In lead cells this limiting voltage may be taken at 1.75
volts per cell. The watt-hour capacity of a battery is equal to the
ampere-hour capacity multiplied by the average voltage during
discharge.
In addition to taking care that the temperature of the cells does
not exceed 110° F. when being charged, precautions are also neces-
sary to prevent the temperature of the battery falling too low,
as a drop in temperature causes a falling off in efficiency. In the
case of the lead cell, freezing must be guarded against in cold weather.
To avoid this, the battery should always be kept fully charged in
cold weather, as a charged cell will not freeze in the temperatures
ordinarily experienced.
Quite different from the lead storage battery is the one manu-
factured by the Edison Storage Battery Company. Here the
positive plate is a steel grid with steel tubes containing nickel hy-
drate and metallic nickel, and the negative plate a steel grid with
steel pockets containing iron oxide. The electrolyte is an alkaline
solution in water.
This battery requires watering occasionally to keep the solution
at the proper level. At long intervals the solution should be re-
newed by standard renewal solution obtained only from the Edison -
Company. This is required after each period of 250 discharges,
about two years in ordinary marine service. In putting the battery
Digitized'by VJiOOQlC
556
ELECTRICITY
out of commission there is nothing to be done except to see that
the solution is a good half-inch above the plates. If too low bring
to proper level by adding distilled water. In putting the battery
in commission, see that each cell has sufficient electrolyte to cover
the plates and give the battery a 12-hour charge at normal rate.
After the first discharge the battery may then be fully charged
in 7 hours at normal rate.
Edison Storage Batteries for Yacht Lighting
(Approximate equipment based on 10-hour service)
Voltage
Number
of
Cella
Lamps
Approximate Length erf Boat
Number
Candle
Power
18 ft. to 30 ft
6
5
6
12
18
6
6
6
30 ft. to 45 ft
12 to 20
10-20
12 to 18
18 to 24
24 to 30#
10
10
10
50 ft. to 75 ft
30
28
26
32
40
10
10
10
90 ft. to 250 ft
110
100
30
to
200
16
Where 60-volt or 80-volt systems are required, 55 cells and 75 cells, respectively,
are recommended.
Notes on Storage Batteries. — All compartments where storage
batteries are installed should be well ventilated and have a con-
stant temperature of about 70°.
Operate a battery only in accordance with the rules furnished
by the manufacturer.
Acid should never be added to a battery except upon the recom-
mendation of the manufacturer.
Never bring a lighted match or other open flame near a battery.
Locate the battery so that no acid can get on any wood work.
The best way to ascertain the condition of a battery is to test
the specific gravity (density) of the solution in each cell with a
DigitizecTby VjiOOQIC
BATTERY CELLS 557
hydrometer. To take a reading insert the end of a rubber tube
in a cell. Squeeze and then slowly release the rubber bulb, draw-
ing up the electrolyte from the cell until the hydrometer floats.
The reading on the graduated stem of the hydrometer at the point
where it emerges from the solution is the specific gravity of the
electrolyte. After testing, the electrolyte must be returned to the
cell from which it was drawn.
The gravity reading is expressed in points; thus the difference
between 1,250 and 1,275 is 25 points. When all the cells are in
good order the gravity will test about the same (within 25 points)
in all. Gravity below 1,150 indicates that the battery is completely
run down or discharged, below 1,200 but above 1,150 less than half
charged, and above 1,200 more than half charged.
A battery charge is complete when, with charging current flowing
at the rate given on the instruction sheet on the battery, all cells
are gassing (bubbling) freely and evenly and the gravity of all
cells has shown no further rise during one hour. The gravity
of the solution in cells fully charged as just mentioned is 1,275 to
1,300.
The best results in both starting and lighting service (the former
relates to the starting of gasoline engines) will be obtained when
the system is so designed and adjusted that the battery is normally
kept well charged. A battery which is to stand idle should first
be fully charged.
Grouping of Battery Cells, (1) Series. — When it is desired to
obtain a voltage greater than that of a single cell, two or more
are connected together in series; that is, the positive terminal of
one cell is connected to the negative terminal of the next, and so on
until the number of cells required to produce the voltage wanted
are connected. For instance, to get a voltage of 11 volts, 10 dry
batteries with a voltage of 1.1 each would be required.
(2) Multiple. — If it is desired to obtain more current, that is,
more amperes without changing the voltage, then more cells must
be placed alongside the others, that is, parallel with the first row,
each row producing the same voltage and joined at the ends, positive
terminals to positive, and negative terminals to negative, thus
adding their currents together at the same voltage.
Generating Sets. — These consist of a gasoline engine, steam
engine or turbine direct connected to a generator. Steam is sup-
plied by the main boilers and is often reduced by a valve to
about 100 lb. at the engine. The engines are of the vertical high
Digitized by VjiOOQ LC
658 ELECTRICITY
speed type, particulars of which are given in the table on page 559.
On the same page are sizes of turbogenerator sets, and it should
be noted that they are much lighter in weight. In large U. S. steam-
ers there is installed besides the main generating set an emergency
one on the deck above, as required by the U. S. Steamboat-
Inspection Service whose rules state: "After January 1, 1915, all
steamers carrying passengers subject to the inspection of this
service which are provided with a plant for electric lighting pur-
poses, the dynamos of which plant are located below the deep load
line, shall have on board an auxiliary plant located above the
deep load line, capable of thoroughly lighting the vessel in case
of an emergency."
Gasoline engine sets are only installed in small craft as motor
boats. With gasoline engines the same close regulation as with
steam turbines and reciprocating engines is seldom obtainable, so
the gasoline units invariably charge storage batteries which fur-
nish the current direct to the lamps.
Generators of the direct current multipolar type are of 100-110
or 200-220 volts for steamers. (See Voltages.) As to the wind-
ings, when a constant current at a variable voltage is required as
in series arc lamp circuits, then a series wound generator is specified,
but on a constant voltage circuit where the distances from the
generator to the load is not great and where there is a small line
loss, then a shunt wound machine is installed and this type is in-
variably selected for marine service. In a compound wound
generator there is compensation for line loss; that is, the voltage
at the terminals is constant and lamps can be run at a constant
voltage even if they are at a considerable distance from the gen-
erator.
To find the Horse Power required for the Engine.
Let / = total current required in amperes
V = voltage
G = efficiency of the generator taken as .9 to .95
M — efficiency of the engine taken as .85 to .90
/ X V
Thenhp=s 746 X G X M
I X V
Kilowatts (kw.) = t mn / and substituting this value jn the
ifUUU above equation
_ kw. X 1,000
hp* " 746 XG XM
See also Determination of Output.
Digiti
zed by G00gk
SIZES
559
i
Sizes. — The tables below give data on gasoline, steam engine,
and turbine electric generating sets. The voltage of the gasoline
may be from 32 to 110, while the- steam units are either 110 or 220,
110 volts being for the lighting circuits and 220 for power.
Gasoline
Kw.
Number
of
Cylinders
Diameter
Inches
Stroke
Inches
Revolutions
per
Minute
Net
Weight
Pounds
5
10
15
4
4
6
3K
4
4
5
6
6
900
750
750
1,400
2,600
3,175
Sturtevant Co., Boston, Mass.
Steam Engine
Size of
Engine
Steam
Pressure
Required
Revolu-
tions per
Minute
Dia. of Pipes
Inches
Kw.
Number
16 c. p.
55-watt
Lamps
Weight
Com-
plete 3et
Pounds
Steam
Exhaust
6H— 10HX6M
7—12X7
8—14X8
8—14X8
10—18X10
100
100
100
150
150
450
400
400
400
350
2
3
3
4
2H
5
5
6
17M
25
35
50
100
320
450
640
910
1,820
5,600
7,300
10,000
14,000
22,000
Sturtevant Co., Boston, Mass.
Steam Engine
(U. S. Navy requirements)
Kw.
Normal Steam Pressure
Pounds
Water (Steam)
Consumption, Pounds
per kw. hour, full load
2J4
100
105
5
100
90
8
100
70
16
10Q
44
24
100
41
32
100
39
50
150
35
100
150
31
Google
560
ELECTRICITY
Turbines
Diameter Pipes
Overall Dimensions
Weight Not Packed
Kw.
Steam
Prenure
Speed
R. p. m.
Steam
Exhaust
Length
Width
Height
125 Volts
250 Volts
1
75to2O0
ft
4000
49
30
28
780
780
2
75to2O0
4000
49
30
28
810
810
2H
75 to 200
m
3600
49
30
28
845
845
4
75 to 200
m
4000
50
30
28
870
870
5
75 to 200
VA
3600
52
30
28
935
935
m
75to200
1H
3600
53
30
30
1000
1000
10
75 to 200
U4
3600
64
30
30
1125
1125
75to200
2
6
3600
68
37
35
1725
1725
15
75 to 200
2
6
3000
70
37
35
1985
1985
75 to 200
2H
8
3000
72
45
45
2735
2735
25
75to200
2
6
3000
78
37
35
2315
2315
75 to 200
2^
8
3000
100
45
45
3065
3065
35
75 to 200
2
6
3000
69
37
35
2550
2550
75 to 200
2H
8
3000
83
45
45
3300
3300
50
75 to 200
2H
3^
8
2800
93
45
45
3575
3500
75 to 200
8
2800
112
52
53
5025
4950
75
75to200
3>*
8
2200
120
52
53
5600
5500
75to200
4
10
2200
123
55
59
6700
6600
100
75to200
3H
8
2200
125
52
53
6000
5900
75to200
4
10
2200
128
55
59
7100
7000
125
75 to 200
4
10
2200
128
55
59
7475
7150
150
75to200
4
10
2000
138
55
59
8100
7950
Sturtevant Co., Boston, Mass.
Tests of Condensing Terry Turbogenerator Setb
i Kw.
Rating
Kw.
Output
Steam
Pressure
Vacuum
Speed
Pounds Steam
per kw.
300
300
225
150
200
200
200
27
27
27
1,250
1,265
1,280
28.6
30.2
34.2
100
100
200
23
1,735
36.08
85
85
32
150
143
27
27
2,240
2,240
32.
38.
7H
10
7.5
3.7
200
200
200
25
25
25
3,800
3,800
3,800
53.5
54.8
69.4
The steam used in the above tests was dry saturated, no moisture,
no superheat. Terry Turbine Co., Hartford, Conn.
Operating and General Notes.*— As all electrical machinery runs
* Abstracts from Care of Naval Machinery. H. C. Dinger.
Digitized by VJiOOQLC
VIOLENT SPARKING 561
at high speeds, be sure that the lubrication is reliable, and the
oil cups filled before starting. .
Become acquainted with the usual temperatures of the different
parts when running, so that any abnormal rise of temperature will
be noticed at once and the cause located.
Use only brass or copper oil cans.
Keep all small tools away from the generator.
Violent sparking of the commutator may be caused by a broken
armature coil or a broken armature and commutator connection.
If the sparking cannot be controlled by the brush adjustments
the machine should be shut down and examined. In some cases
the sparking may be due to a dirty commutator. If the pressure
of the brushes on the commutator is too light, they may jump
and run irregularly, thus causing sparking.
A very small amount of lubricant on the commutator is usually
found to aid in smooth running and save the surface from scoring.
If the generator has become demagnetized it will refuse to gen-
erate current when the speed is up. To remedy this, either tap
the field with a light hammer or, if this fails to produce the desired
result, reverse the brushes, that is, turn them around 180° of the
commutator circle (if a two-pole machine) so that they change
places with each other, and run the machine for a short period with
reversed current. This tends to restore the residual magnetism;
afterwards replace the brushes in their original positions.
In starting it is advisable to open the throttle gradually and
bring the engine or turbine up to speed slowly.
When turbines are running on part load, it is recommended
that instead of partly shutting all the steam nozzles, a few be shut
tight, leaving wide open a sufficient number to give the requisite
power.
Electric motors are series, shunt, and compound wound. Series
motors are for immediate loads, are easily started even under heavy
loads, but a variation of the load causes a great variation in the
speed. Hoists and cranes are operated by series motors.
Shunt motors have their speed nearly constant for a variable
load. They do not start so easily under a heavy load as series
motors, and a variation of load causes little variation of speed.
This type is for driving blowers, ventilating fans, centrifugal pumps,
and machine tools.
Compound wound start on heavy loads, the variation of the
speed being proportional to the load. They are suitable for
Digitized by VjiOOQ 1C
662 ELECTRICITY
elevators and machines that have to be constantly started and
stopped.
Motors for ship work are generally of 110-120 volts, the large
sizes having starting boxes. The type of frame selected, viz.,
open, semi-inclosed, or inclosed, depends on the location of the
motor in service. When with an inclosed frame it must be larger
than with an open or semi-inclosed, to offset the lack of ventilation
and consequent excess of heat in the armature. In other words,
an inclosed motor has less output than a semi-inclosed, but it has
the advantage of being practically dust and moisture proof.
All motors should have an efficient oiling system, and should
carry an overload of say 25% for two or more hours without an
extreme rise in temperature. Care should be taken that when
running there is no sparking at the commutator.
In sizes above 5 h. p. multipolar motors are specified by the
U. S. Navy Department, and below 5 h. p., bipolar. A special type
known as the Interpole has been developed by the Diehl Manu-
facturing Company, of New York. Here commutation is secured
by means of separate poles placed midway between the main poles
and fitted with a winding carrying full armature current to establish
a field for commutation entirely independent of the main field.
The primary object of the interpoles is to assist in the commuta-
tion so that all sparking may be avoided. Where the duty is ex-
tremely light, or where the series winding of the main poles is suffi-
cient to provide necessary commutation characteristics, interpoles
may be omitted to reduce weight and cost.
To Calculate the Horse Power of Motors.
Direct current
« Wolts X amperes X motor efficiency
Brake horse power =
746
Alternating current
Brake horse power —
volts X amperes X power factor X -y/numberofphases XmotoreflSciency
746
Average motor efficiency 85%.
Weight of Motors. — The following table, furnished by the B. F.
Sturtevant Co., Boston, gives the approximate weight of 110-volt,
direct-current motors for various speeds and horse powers:
Digitized by VjOOQ IC
SHIP MOTORS
563
Sizes and Weights of Ship Motors
Speed
Horse Power
Weight, Pounds
1,630
4
1,295
3
1,070
3
448
790
2
510
1.5
1,440
6
1,110
4
903
4
517
700
3
478
2
1,366
9
1,015
6
804
5
650
563
3.5
383
2.5
1,386
10
978
7.5
852
6
826
611
5
409
3
1,190
14
988
14
733
8
1,107
579
6
478
6
1,267
16
1,007
14
834
14
1,475
710
10
488
6
984
26
790
22
655
18
1,896
557
12.5
424
10
•
947
30
727
534
22
15
2,330
423
15
823
35
630
465
25
18
2,899
368
18
Digiti
zed by G00gk
564 ELECTRICITY
Current Taken by 110-Volt Direct Current Motors
Horse Power
Amperes
Horse Power
Amperes
H
4.5
15
113
H
6.8
20
150
l
9.0
25
188
m
13.6
30
226
2
16.9
40
301
3
25.4
50
376
4
33.8
60
452
5
42.3
70
527
7V2
56.5
80
602
10
75.3
90
678
Motors for Ship Work.— The horse powers given are for open
and semi-inclosed motors; for an inclosed motor it is 30% less.
Installations of Motors on Warships*
Boat Cranes. — Both rotating and hoisting motors are series
wound, interpole type, of 400 r. p. m., the hoisting motor being
50 h. p. and rotating 40 h. p. (U. S. battleships Arkansas and Texas).
Deck Winch. — 35 h. p., 350 r. p. m., compound wound 50%
series and 50% shunt, without interpoles (U. S. Montgomery,
Virginia, Florida, Arkansas and Texas).
Ammunition Hoist. — 3 h. p., 400-530 r. p. m., shunt wound with-
out interpoles (U. S. Arkansas and Texas).
Ventilating Fans. — For small fans of 600 cu. ft. and under,
motors as a rule series wound. All others shunt.
Forced Draught Fans. — 39 h. p., 630-795 r. p. m., nominal capac-
ity 28,500 cu. ft. per min. (U. S. Florida). #
Fresh Water Pump. — 3 h. p., 1,100 r. p. m., compound wound
(U. S. Utah and Arkansas).
Steering Gear Motors. — For some cruisers of about 5,500 tons,
motors of 40 h. p., 300 r. p. m. have been installed, while for battle-
ships 150 h. p., 250 r. p. m. All compound wound.
Motors for Turning Turbines. — Special winding, 5 h. p., 300-
600 r. p. m. (U. S. Florida and Arkansas).
Turret Turning Motors. — The differential gear as applied to
12-, 13- and 14-inch guns covers the use of two motors for each
gear, the larger one rated at 25 h. p., adjustable speed 300-900
r. p. m., and the smaller one 10 h. p., adjustable speed 300-900 r. p. m.
* Abstracts from Naval Electrician's Handbook. W. H. G. Bullard
Digitized by vjOOQ 1C
ELECTRIC CAPSTAN 565
Gun Elevating Motors. — Shunt wound.
Electric Capstan installed on the U. S. New York and part of
equipment of latter battleships, designed to hoist 4,000 lb. at a
speed of 200 ft. per minute, or a load of 16,000 lb. at 50 ft.
Anchor Windlass. — 150 h. p., 250 r. p. m., 120 volts, 6-pole, com-
pound wound with interpoles, reversible (U. S. Nevada).
See also Ship Machinery.
Motor Starting and Controlling Devices.* — A rheostat is an in-
ternal shunt for reducing the amount of current passing through
a circuit by interposing resistance in it. Rheostats for intermittent
service will carry a much larger current for a short time than those
which are used continuously.
t A controller is a device for making the proper electrical con-
nections between the main supply lines and a motor, so as to control
the direction and speed of rotation. They are for the control of
heavy currents in motors of above 10 h. p., as in such equipments
as boat cranes, deck winches, turret turning motors, ammunition
hoists, and in general where there are continuous starting and
stopping and changes of direction and speed.
There are three classes of controllers designed according to the
work they are to do. Those built by the General Electric Co. of
New York are arbitrarily designated as the R, B and P types.
The R controllers are rheostatic in their method of operation,
and are for starting, stopping, reversing, and controlling the speed
of motors. They are particularly adapted for motors that carry
a heavy load in either direction.
B controllers are designed to give electric breaking; that is, the
motor is made to run as a generator by the momentum of its arma-
ture or load, and in this way reduces its speed or stops itself.
P controllers are installed where the voltage of the generator
is to be varied, to obtain a change of speed of the motor.
Panels are to protect motors against the following conditions:
(1) overload, (2) failure of voltage on line, (3) excessive rush of
current caused by too rapid starting, and (4) funning on resistance
which is only designed for starting. A standard panel for the
U. S. Navy for motors of 10 h. p. or less consists of an enameled
slate 12 ins. wide by 24 ins. long and 1 in. thick, supported on
iron side frames. On the panel is a main switch, rheostat switch,
circuit breaker, and two inclosed fuses. All small parts not in
* Abstracts from Naval Electrician's Handbook. W. H. G. Bullard.
Digitized by VjiOOQIC
566 ELECTRICITY
magnetic circuit are of noncorrosive material, and where necessary
moving steel parts are copper plated. The weight of a panel as
outlined is approximately 100 lb. For motors larger than 10 h. p.
the same apparatus is required, only the parts are larger.
Solenoid Brakes. — These are fitted on motors designed for
hoisting and lowering weights and are intended to check the speed
or even stop the motor and hold the load in case of failure of cur-
rent, and to prevent the load from falling and running the motor
as a generator. Motors for cranes, deck winches, turret ammu-
nition hoists, and similar equipment have solenoid brakes. There
are two types: (1) an electrically operated band brake, and (2) an
electrically operated friction disk brake. The former is fitted to
chain ammunition hoists, and with a modification to deck winches,
and the latter with modifications to other forms of hoists.
Ardois Signals. — These are installed on warships for night sig-
naling and consist of four double lanterns, each containing a red
light and a white light, that are hung from the top of a mast, one
under the other and several feet apart. By means of a special
controller any number of lanterns may have either red or white
lamps lighted, thus producing combinations by which a code can
be signaled.
Electric Heaters and Cooking Devices, see page 573.
Electric Turbine Propulsion, see Turbines.
Electric Steering Gear, Capstans, etc., see Ship Machinery.
Heating by Electricity, see Heating.
Costs of Electric Installations, see Costs, Prices and Estimates.
Digiti
zed by G00gk
SECTION VIII
HEATING, VENTILATION, REFRIGERATION,
DRAINAGE, PLUMBING, FIRE EX-
TINGUISHING SYSTEMS
HEATING
To Calculate the Heat Passing Through a Ship's Side or Through
a Bulkhead. — Assume the temperature of the stateroom to be
maintained at 70°, while the outside temperature will depend, on
the route the steamer follows or, say, a minimum temperature of
30° for the sea and 40° for the air outside the staterooms, as the
air in the passageways is about 10° above that of the outside atmos-
phere.
For example, take a stateroom 12 ft. long, 11 ft. 6 ins. wide,
and 8 ft. high, having a cubic capacity of 1,104 cu. ft. The surface
along the side of the hull will be 12 ft. by 8 ft. or 96 sq. ft.; that
exposed to passageways or other staterooms will be 8 ft. by 35
ft. or 280 sq. ft.; the deck above, 12 ft. by 11 ft. 6 ins. or 138 sq. ft.;
and the same amount on the deck below.
Of the ship's side 96 sq. ft. is subject to a difference of 40° (70°
inside and 30° outside). Iron has a conductivity of about 233
B. t. u. per sq. ft. per hour per one degree Fahrenheit. Thus the
quantity of heat passing out would be 233 X 96 X 40 = 894,720
B. t. u. per hour, requiring a very large heating apparatus for the
ship.
From the above will be noted the difficulty in warming parts of
a ship where one side of a compartment is exposed to the weather,
and the advantages of wood vessels in cold climates. To reduce
the heat loss , through the shell plating, a wood lining is fitted,
between which and the plating are subdivisions forming air spaces.
In this manner the leakage of heat may be reduced to .5 B. t. u.
per hour per degree Fahrenheit difference of temperature for each
square foot; or if wood alone one inch thick, the loss would be about
.8 B. t. u.
Assuming that a wood lining with air spaces is fitted and that
the loss of heat is .5 B. t. u. per hour per degree Fahrenheit, then
the loss along the ship's side having an area of 96 sq. ft. would be
668 , HEATING
40° X .5 B. t. u. X 96 sq. ft. - 1,920 B. t. u. per hour, and the
remaining 556 sq. ft. of the other 5 sides (40° X .5 B. t. u. X 556
sq. ft. = 11,120 B. t. u.) making a total of 13,040 B. t. u. per hour.
As a change in temperature of one degree corresponds to 965.7 B. t. u.,
13 040
thus the temperature of the room would be lowered '- _■ = 13.5°.
yoo.7
Suppose it ,is required to find the capacity of an electric heater
for the above room. One watt = 3.41 B. t. u. per hour, then the
13 040
heater must deliver _' = 3,806 watts per hour.
3.41
Or suppose the room is to be steam heated, the steam having a
temperature of 210°. The square feet of radiation required
total B. t. u. lost from the room per hour
1.7 (temp, of steam in radiator — temp, outside radiator)
13,040 Ao*ann
"1.7(210-30) =42-6s*ft'
(The above is from Heating and Ventilating of Ships, C. B. Walker.)
Vessels are heated by steam, hot air (thermotanks), and by
electricity.
Heating by Steam. — The steam may be taken from the auxiliary
steam line or there may be an independent line run, in both cases
calling for a reducing valve for reducing the steam to about 15 lb.
Beyond this valve the steam goes direct to the radiators.
There are two systems of piping, viz., the two-pipe and the
one-pipe. In the former there is a supply pipe to the radiators
and a return from them to a tank from which the condensed steam
is pumped to the hot well. There should be a by-pass from the
return to the condenser to suck the radiators and pipe line dry,
thus preventing any remaining water from freezing and bursting
the radiators if the steamer is laid up in cold weather. When
the steam pipe is less than 3 ins. diameter, it is customary to make
the return one or two sizes smaller. If the steam is over 3 ins., the
area of the return may be about one-quarter that of the steam. In
the one-pipe system the steam is delivered to the radiators, and
the condensed water is drawn off by cocks.
It is usual with steam heating systems to have air pipes con-
nected to the radiators, so that the air that is brought by the steam
can escape.
Steam Heating System on U. S. Vessels. — Radiator coils one-
inch seamless drawn brass pipe, iron pipe size.
Digitized by VjiOOQIC
RADIATORS 569
Radiators consisting of pipes along the decks, 2-inch brass pipe,
iron pipe size.
Circuit steam and drain pipes seamless drawn brass pipes, iron
pipe size, connected by composition fittings.
The heating plant will work at a pressure of about 50 lb.
The number of cubic feet of space to be heated allowed per square
foot of radiator surface will be as follows:
Cubic Feet
Pilot and chart houses 50
Captain's cabin, staterooms, bath and water
closet 60
Sick bay and bath room 60
Wardroom country and staterooms 80
Wardroom officers' staterooms 80
Storerooms 100
Dispensary 80
Berth and main decks forward of barbettes, crew's
lavatory 100
Main deck inside armor 100
Steering engine room 125
Berth deck and inside redoubt 125
Radiators and heaters will be arranged in circuits, each circuit
being so connected that it can be operated independently of the
other.
For a 160-foot steamer the following steam heating system was
specified: "Steam for the radiators shall be taken from the auxil-
iary steam pipe through reducing valves and manifolds. Each
steam circuit shall be plainly marked. There will be one steam
trap located in the lower engine room, so as to drain all the heaters.
This trap shall be connected up and provided with a suitable by-
pass. A branch shall be led outboard.
"AH heater pipes shall be of wrought iron, and so led that there
will be no pockets where water can collect.
"The area of the radiators shall be apportioned as follows:
Chart room, 1 square foot to 30 cubic feet
Captain's cabin, 1 square foot to 60 cubic feet
Wardroom, 1 square foot to 60 cubic feet
Crew's quarters, 1 square foot to 50 cubic feet
Officers' rooms, one small heater in each
Petty officers' rooms, one small heater in each room
"Galvanized iron drip pans shall be fitted under all radiators.
"The radiators shall be of cast iron."
Size of Radiators. — Experiments have shown that the ordinary
Digitized by vjOOQIC
570
HEATING
cast iron radiator located in a room and surrounded with com-
paratively still air gives off heat at the rate of 1.7 B. t. u. (1.6 to
1.8 or 1.7 average) per square foot per degree difference between
the temperature of the surrounding air and the average tempera-
ture of the heating medium per hour. This is called the rate of
transmission.
To find the square feet of radiation for any room, divide the
calculated heat loss in British thermal units per hour by the quan-
tity 1.7 times the difference in temperature between the inside
and the outside of the radiator. Thus
square feet of radiation =
Total B. t. u. lost from the room per hour
1.7 (Temp, of steam in radiator — Temp, outside radiator)
A radiator under stated conditions and under a heavy service
requires one-fourth of a pound of steam per square foot of surface
per hour. To determine approximately the amount of radiating
surface a pipe will supply, assume 100 sq. ft. for each square inch
of sectional area of pipe.
One square foot of steam-radiating surface is often estimated
to give off 250 B. t. u. per hour when operating under a pressure
from 2 to 5 lb. per square inch in a room temperature of 70°. As-
suming a steam temperature of 220° which corresponds to a pressure
of about 3 lb., the total difference in temperature is 220 — 70 =
250
150°, r-^r = 1.67 B. t. u. per degree difference per square foot per
hour. This factor is not constant and varies with the type of
radiator and difference in temperature.
A single-column radiator is more efficient than a 2- or 3-column,
because the surface is more exposed to the surrounding air. Also
a low radiator is more efficient than a high one as there is in the
Sizes of Tappings for Radiators
l-Pipe System
2-Pipe System
Surface, Sq. Ft.
Size, Ins.
Surface, Sq. Ft.
Steam, Ins.
Return, Ins.
25
25-50
50-90
100-160
1
IK
m
2
30
30-50
50-100
100-160
X
k
X
X
1
IX
Heating and Ventilating of Ships. C. B. Walker.
Digitized
by Google
THERMOTANKS
571
former a continuous upward current of air around the surface of
the radiator. The air in its passage from the bottom to the top
becomes heated and as it reaches the top the transmission of heat
is less rapid because of the less difference in temperature between
the steam and the air.
Approximate B. t. u. Transmitted per Square Foot per Degree
Difference per Hour for Various Types of Radiation
When the Difference of Temperature is 150° F.
Type of Radiator
Height
22 Ins.
26 Ins.
32 Ins.
38 Ins.
1-column 1.90
2-column 1.80
3-column 1.70
4-column 1.60
Window radiator
Wall radiator, horizontal. .
Wall radiator, vertical
Pipe coils
1.86
1.75
1.65
1.55
1.83
1.71
1.60
1.50
1.80
1.67
1.54
1.45
1.85
1.95
1.90
2.00
Equivalent Square Feet of Heating Surface in One Linear
Foot of Standard Wrought Iron Pipe
Diameter of Pipe, Ins.
Square Feet of Heating Surface
H
.275
l
.346
IX
.434
IX
.494
2
.622
2>i
.753
3
.916
4
1.175
6
1.739
Heating by Thermotanks. — These consist of coils of pipes around
which air is drawn that is forced through ducts by a fan to the
different parts of the vessel. There are three forms of thermo-
tanks, viz., bottom suction and top suction when installed exposed
to the weather as on decks, and the 'tween-deck form which takes
the air from a duct leading to any convenient supply of fresh air.
The pipes are connected to steam mains, hence hot air can be de-
livered to any part of the vessel. See Figs. 91 and 92.
572
HEATING
Digiti
zed by G00gk
HEATING BY ELECTRICITY 573
Heating by Electricity. — All electric heating apparatus is based
on the fact that when a current of electricity passes through a
conductor heat is liberated in direct proportion to the resistance
of the conductor and the square of the strength of the current.
Let H = quantity of electricity delivered in time t
R = resistance of conductor in ohms '
C 0 = current in amperes
E = the difference of pressure in volts at the terminals of
the conductor or heater
Then H (the quantity of electricity liberated) = C2 X R X t
E E
and from Ohm's Law C = -^ and R = ~-
Hence C2 X R X t - C* X ^ Xt = CxEXt = ^^
As H can be expressed in watts and as one B. t. u. equals 17.58
watts (one watt = .0568 B. t. u. per minute or 3.41 B. t. u. per
hour) then the heat given off from an electric heater can be calcu-
lated from the above formula.
Suppose it is required to find the number of heat units (B. t. u.)
given off by an ordinary 16 candle power incandescent lamp
working at 100 volts and taking a current of .6 ampere.
Electric energy (watts) = volts X amperes = 100 X .6 = 60.
The heat given off or the B. t. u. per minute *= 60 X .0568 = 3.480.
For electric heating there are two kinds of radiators, viz., lumi-
nous and non-luminous. The former are practically several large
incandescent lamps, the light from which is of secondary impor-
tance to the heat given off. They are adapted for intermittent
service, as removing the chill from a room, but for a room where
it is required to maintain a high steady temperature for several
Device
Watts per Hour Required
Coffee percolator (2J^ pints)
380
6-in. disk stove
500
8-in. disk stove
800
Chafing dish
500
Small luminous heater . ,.....*
500
Non-luminous heater
3,000
300
Frvinit Dan
Toaster
500
Tea samovar
500
y Google
574
HEATING
hours a non-luminous heater is more satisfactory, consisting of
resistance coils by passing a current through which heat is given off.
Working on the same principle as non-luminous heaters are
stoves, coffee percolators, and other domestic appliances. On page
573 is a table showing the current, which should be 110 volts, required
for various devices.
Special Systems. — Among the special systems thaj have been
installed for heating is the Nuvacuumette (AshweU & Nesbit,
Leicester, Eng.) in which the steam admitted to the radiators is
automatically controlled on its admission, there being no valve on
the outlet of the radiator. This method causes the vacuum carried
in the return pipes to extend into the radiator itself, making it
possible completely to fill the radiator with water vapor at a tem-
perature of 180° F. In large installations a vacuum pump is pro-
vided which may be dispensed with in small. The pump is placed
Figure 92. — Fan and Heating Coils.
Digitized by VJiOOQlC
VENTILATION 575
at the end of the return condensed vapor main into which all- the
returns from the heating Units are directly connected without the
interposition of any valve. A further development of the above
is the fitting, on the inlet to the radiator, of a device which auto-
matically shuts off the supply of steam when the temperature has
reached a predetermined point, and should it fall below, the valve
opens allowing steam to enter.
Another system sold under the trade name Hlghlow (A. Low &
Sons, Glasgow) has been installed on many steamers. The pres-
sure in the steam mains may be from 5 to 50 lb., and the supply
may be taken at the same pressure as other auxiliaries, or a con-1
nection may be taken from the exhaust main and the vessel
heated by exhaust steam. The advantage of having steam at a
high pressure instead of a pound or two is that smaller mains may
be fitted. Each radiator is fitted with an exhaust valve. The steam
mains are usually carried overhead and the exhaust mains below.
The steam enters the radiator through a stop valve and then a
thermostatic valve, the latter being designed to give a large opening
with a small variation in temperature. This valve is set for the
desired temperature in the radiator and as soon as enough steam
has been admitted to obtain this it automatically closes, not opening
again until the temperature has dropped in the radiator below that
for which the valve is set. As it is impossible on board ship to have
sufficient run on the exhaust pipe to clear it of condensed water,
it is necessary to fit a vacuum pump. To provide against the
possible breakdown of this pump a connection is made to the con-
denser, or a duplicate pump is fitted which is installed in the engine
room, and the discharge is led into the hot well. A vacuum regu-
lator is fitted to control this pump and when the desired vacuum is
reached the steam supply is automatically cut off by the valve
which opens again immediately the vacuum decreases. *
On some torpedo boat destroyers, instead of having a return
drain from the radiators the condensed water is discharged directly
overboard. This arrangement saves weight, that is, the weight of
the return piping and its fittings.
VENTILATION
Sea air, which is taken as the purest form of air, contains about
3 volumes of carbonic acid gas in 10,000 volumes of air. The limit
on shore is from 8 to 10 volumes in 10,000 of air.
For perfect ventilation the air should circulate at a velocity of
Digitized by VJiOOQlC
576 HEATING
from 4 to 6 ft. per second. In lavatories and cattle spaces, ozone-
making apparatus is often installed for purifying the air. An
average person requires about 1,800 cu. ft. of air per hour, so that
the amount of air needed for the ventilation of staterooms and
living quarters may be obtained by the formula; quantity of air
in cubic feet per hour — 1,800 X number of people. Below is the
time specified to remove the air from different compartments of
a war vessel.
Minutes
Quarters on orlop deck 10 to 12
Water-closets 4 to 6
Staterooms 8 to 12
Magazines 6 to 8
Engine room 2
Ice machine room 3
Dynamo rooms Ji
The velocity of air in ventilating systems on shore is about 7 ft.
per second. A steamer running at 8 to 10 knots produces an air
current of 13 to 17 ft. per second, at 16 knots 27 ft., while in the
Mauretania, a 24-knot Atlantic liner, the velocity is about 40 ft.
per second. In hot climates the air current produced by the speed
of the vessel is useful for cooling the compartments between decks,
but in cold climates the air must be warmed as by thermotanks or
shut off.
Air Pressure. — This is measured by a U tube having water in
the bent portion, one end of the tube being open to the air and the
other connected to the duct whose pressure is to be measured.
The readings are inches and fractions; thus a reading of 1 in. water
gauge is equal to .55 of an ounce pressure per square inch.
Every duct through which a fan delivers air offers a certain
resistance to the flow of the air.* This resistance is due to the
friction between the air and the surfaces that it comes in contact
with, and for a given duct varies directly as the square of the vol-
ume delivered. A certain pressure is required to overcome this
resistance and this pressure is known as the static pressure and
is measured in inches of water gauge.
Systems. — Compartments above the water line having air ports
can be ventilated by natural means, but those below must be by
artificial, either of two systems, viz., plenum or exhaust, being
selected. In the plenum, fresh air is drawn down the ventilators
by fans and forced through sheet iron ducts to the various com-
partments. In the exhaust system, fans draw the foul air from the
Digitized by VJiOOQ 1C
PRESSURE IN OUNCES
577
Pressure in Ounces per Square Inch, Corresponding to Va-
rious Heads op Water in Inches
Decimal Parts of an Inch
Head
in Ins.
.0
.1
.2
.3
.4
.5
.6
.7
.8
.9
0
0.06
0.12
0.17
0.23
0.29
0.35
0.40
0.46
0.52
1
0.58
0.63
0.69
0.75
0.81
0.87
0.93
0.98
1.04
1.09
2
1.16
1.21
1.27
1.33
1.39
1.44
1.50
1.56
1.62
1.67
3
1.73
1.79
1.85
1.91
1.96
2.02
2.08
2.14
2.19
2.25
4
2.31
2.37
2.42
2.48
2.54
2.60
2.66
2.72
2.77
2.83
5
2.89
2.94
3.00
3.06
3.12
3.18
3.24
3.29
3.35
3.41
6
3.47
3.52
3.58
3.64
3.70
3.75
3.81
3.87
3.92
3.98
7
4.04
4.10
4.16
4.22
4.28
4.33
4.39
4.45
4.50
4.56
8
4.62
4.67
4.73
4.79
4.85
4.91
4.97
5.03
5.08
5.14
9
5.20
5.26
5.31
5.37
5.42
5.48
5.54
5.60
5.66
5.72
From Heating and Ventilation, B. F. Sturtevant Co.
compartments and exhaust it up the cowls, the fresh air entering
through the ventilating ducts. Toilets, kitchens, and rooms
where it is necessary to remove odors, smoke, dust, or gases should
be ventilated by the exhaust system. As a whole the pressure
system is preferably, as the leaking in of foul air from one room
into another is prevented by the pressure of the air.
Air which has been breathed is warmer and more moist than
pure air and hence rises to the top of a compartment. Exhaust
openings, therefore, are located near the top. The supply and
exhaust openings are placed as far away from each other as may
be practical, to prevent the entering air from escaping through
the exhaust opening.
Another system, or rather a combination of ventilating and
heating, is known as the thermotank. This consists of a fan and
pipes through which steam flows, all inclosed in a suitable casing.
Air is drawn from the outside, is warmed by coming in contact
with the hot pipes, and is then forced by the fan through ducts
to the various parts of a- vessel. By using brine instead of steam
a vessel could be cooled. See Figs. 91 and 92.
Many engineers recommend that the ventilation system should
be considered apart from the heating. The advantages claimed
are: (1) the steam required in the warming system is reduced, as
only that volume is condensed which is necessary to maintain the
desired temperature of the compartment, thus saving coal; and (2)
the ventilating units being periodically out of commission, there is
saved the power needed by them.
Digitized by LiOOQ 1C
578
HEATING
The Nesbit system (Ashwell & Nesbit, Leicester, Eng.) of warm-
ing and ventilating is separate, as just outlined. During cold
weather it is necessary to temper the air and this is done by passing
it over a series of air heaters, the temperature of the latter being
about 212° F. To maintain the purity of the air in the various com-
partments, exhaust fans draw out the vitiated air. In hot climates
the air heaters are transformed into coolers by passing through them
a cooling mixture.
Ventilation of Oil Steamers. — Upon emptying an oil tank quan-
tities of gas are given off from the oily bulkheads, and as this gas
is about three times as heavy as air it accumulates and lies at the
bottom. This may be removed by using as conduits the large oil
suction pipes after the oil is withdrawn, the impure air being with-
drawn by the pumps. To secure a quicker action a centrifugal
Figure 93. — Arrangement for Ventilating Engine Room.
Digitized by VjivJ\J'
ile
VENTILATORS 579
fan may be substituted for the ordinary piston pumps, or instead
the tanks may be cleaned by steam in connection with a system
of continuous ventilation. See Oil Carriers.
Engine Room Ventilation. — Here, if natural ventilation is relied
on, the ventilators should extend as far down in the engine room
as practical without interfering with the machinery, with branches,
if feasible, to both sides of the ship. In large vessels there may be
a system of ducts and ventilators, air being circulated by a fan
or fans. In fine weather the skylights are kept open, but even if
they are closed the ventilators should be of sufficient size to pre-
vent the engine room from becoming too hot.
On several transatlantic liners (Aquitania, Transylvania, Tus-
cania, etc.), for distributing the air around the engine room, at
the bottom of the ventilators extending above the upper deck are
large open fans as shown in Fig. 93. When desired the air may
be changed 120 times an hour without uncomfortable drafts. The
air is drawn, not forced, down from the upper deck and is delivered
latterly by an open fan which is placed as low down in the engine
room as practical so as to flood the entire engine room with air,
the cool incoming air falling towards the floor displacing the heated
air and expelling it up the main hatch or hatches or other exits,
no exhaust fans being required. The impellers for these open fans
are scooped on the inlet side and are of such shape that they slice
into the incoming air and divert it gently from the axial into the
radial direction. Outfits as just outlined are built by J. Keith
& Blackman, London.
Ventilators. — These may consist of cylindrical steel plates ex-
tending to just below the deck, with an upper part that can be
turned by hand so the mouth of the ventilator can face any direc-
tion. This type is for holds, engine and boiler rooms. Instead of
the large mouth there may. be vertical flues, which type is used for
galleys, while for staterooms those with a mushroom top that can be
raised and lowered by a screw are often installed. The ventilators
to the firerooms of some torpedo boat destroyers have a cylindrical
part of steel plates riveted to the deck and a hinged top. In bad
weather the top can be brought down so that it is horizontal, and
air may enter between the top and the cylindrical sides.
Ventilators to stokeholds should have an aggregate transverse
area of .45 sq. in. for each pound of fuel burned per hour, or .675
sq. in. per i. h. p. for ordinary merchant vessels, or .75 sq. in. per
i. h. p. for fast steamers on short runs and for warships. The
Digitized by VJiOOQ 1C
580 HEATING
areas of the ventilator mouths should not be less than the following
proportions:
Sq. in per pound of fuel
Vessels
1.35
10 -knot
1.24
1234-knot
1.13
15 -knot
1.03
17J^-knot
.93
20- -knot
.85
22J4-knot
Fans. — Theoretically there should be a difference in the form
of the wheel designed for pressure and exhaust, but practically
the difference between a blower and an exhauster is one of adap-
tation rather than construction. A blower forces the air into a
given space, while an exhauster removes the air. (See also Draft,
page 391.)
A fan for induced draft must be larger, in the sense that it must
allow a larger volume of air to pass through it, than one for forced
draft, because the volume of the hot gases is larger than the volume
of the air that is to be delivered to the fan. In the ventilating
of saloons, cabins, etc., the difference in the volume of the air will
not be great, but cafe iriust be taken not to make the outlets smaller
than the inlets. The liner Lusitania, in addition to the thermo-
tanks, had 12 exhaust fans connected to the trunks of the galleys
and lavatories, the fans being of sufficient capacity to change
the air at least 15 times per hour.
There are certain trade definitions for describing a fan; thus,
angular discharges are designated as top angular up blast discharge,
top angular down blast discharge, bottom angular up blast or
bottom angular down blast discharge. As one stands facing the
outlet of a fan, a motor or an engine appearing on the right side
of the fan characterizes the fan as being right-handed, and if on
the left, left-handed.
Of the types manufactured those sold under the trade name
Sirocco have given excellent results. The runner is of the drum
form with a large inlet chamber inclosed by a large number of long
narrow blades that are curved forward. A peculiar feature of this
fan is that the air leaves the blades at a higher velocity than the
speed of the runner. This type is particularly adapted for high pres-
sures, and where the air has to be forced through long ducts. It
is not, however, reversible. The Sicorro is built by the American
Blower Co., 'Detroit, Mich.
Digitized by LjOOQ LC
PROPELLER FAN
581
Another type of multivane fan is one where the blades are curved
radially, and in addition each blade has several cup-shaped de-
pressions which grip the air and overcome largely the tendency of
the air to slip along the blades to the side opposite the inlet. This
type is very efficient and is built by the B. F. Sturtevant Co.,
Hyde Park, Mass.
In other fans the blades are shaped somewhat like a screw pro-
peller and the action is the same. While the air is being rotated,
at the same time, owing to the obliquity of the vanes, it is propelled
parallel to the axis of the fan. These fans do not deliver the pres-
sure nor are they as efficient as multivane fans when the air has to
travel through long duets with curves. They are reversible.
Figure 94.— Propeller Fan.
Fans are direct connected to steam engines, turbines, and electric
motors (see Electricity); in many cases the latter are preferable.
In motor boats small fans 18 to 24 ins. in diameter, driven by an
electric motor taking the current from the lighting system, are often
installed, the current required being only a fraction of a horse power.
Besides the thermotank outfits (see Systems above), there are also
plenum ventilating cased fans (trade name Rhigothermo, built by
J. Keith & Blackman, London) (see Fig. 92), consisting of a fan and
Digitized by vjOOQ 1C
20
582 HEATING
heater coils, the air flowing around the coils and thence to the
distributing ducts. The mechanical efficiency of a Rhigothermo
unit may be stated: that with a difference of temperature of 40° F.
between the outside air in cold weather and of the air delivered into
the main ducts, every 1,000 cu. ft. of air so delivered at a constant
pressure of 2 ins., requires for electrical current the expenditure
of H h. p., the fan assumed to be driven by an electric motor.
To Find the Horse Power Required to Drive a Fan. — Here the
pressure on the entire cross-sectional area of the duct must be taken.
For instance, if the air is moving at the rate of 500 ft. per minute
under a pressure of 2 ins. water gauge, the duct being 4 ins. by
. 3 ins., having an area of 12 sq. ins., the total pressure will be 12 X
2 = 24 ins. water gauge or 13 ounces, as one inch water gauge is
equal to .55 ounce per square inch. Let the total pressure in pounds
per square inch = 13 ounces or .81 lb. = p, and v = velocity of the
air in feet per minute = 500.
mu ^ u P Xv .81 X 500 A1_ ,. , . x.
Then the h. p. = 33-^ - 33,000 = 012' whlch 1S the
horse power for the air only. Hence in estimating the actual h. p.
required, the result obtained from the formula should be doubled.
For practical purposes the capacity of a fan in cubic feet per
revolution will equal .4 the cube of the diameter in feet. The
volume of air delivered by a fan varies directly as the speed, while
the power required varies as the cube of the speed. That is, doub-
ling the speed doubles the volume of air, and the power required
is increased eight times.
Ducts are made of light galvanized iron sheets with the inside
laps in* the direction of the air current. The resistance offered,
to the air depends directly on the length of the duct, and inversely
as the cross-sectional area. The loss due to friction of air on the
sides increases with the square of the velocity of the flow, so if the
velocity is doubled the loss due to friction is increased four times.
.The smaller the duct the greater is the resistance to the air.
In galvanized iron, pipe turns of 90° should be constructed with
at least 5 pieces and with a radius of curvature on the inner side of
the elbow at least equal to the diameter of the pipe. Branches should
lead from the main duct at an angle of about 30° so that the direction
of air flow entering a branch will not be suddenly changed. When-
ever it is necessary to change the size of a pipe, this should be done
by a gradually tapering connection.
Digitized by LjOOQ IC
Velocity, Volume and Horse Power Required When Am
Under Given Pressure in Ounces per Square Inch is
Allowed to Escape into the Atmosphere
Velocity of Dry Air at
Volume of Air
50° F. Escaping into the
in Cu. Ft. Which
Horse Power Re-
Pressure
Atmosphere through any
May be Discharged
quired to Move
in Ounces
Shape of Orifice in any
in One Minute
the Given Volume
per Square
Pipe or Reservoir in
Which the Given Pressure
Through an Orifice
of Air Under
Inch
Having an Effective
the Given
is Maintained, in
Area of Discharge
Conditions
Feet per Minute
of 1 Sq. In.
N
1828.4
12.69
.00043
n
2585.0
17.95
.00122
N
3165.1
21.98
.00225
n
3653.8
25.37
.00346
%
4084.0
28.36
.00483
N
4472.6
31.06
.00635
N
4829.7
33.54
.00800
1
5161.7
35.85
.00978
IN
5473.4
38.01
.01166
IK-
5768.0
40.06
.01366
IN
6047.9
42.00
.01575
IN
6315.2
43.86
.01794
IN
6571.3
45.63
.02022
IN
6817.6
47.34
.02260
IN
7055.0
49.00
.02505
2
7284.4
50.59
.02759
zy8
7506.7
52.13
.03021
2N
7722.2
53.63
.03291
2^
7931 .8
55.08
.03568
2^
8135.7
56.50
.03852
2^
8334.4
57.88
.04144
2N
8528.3
59.22
.04442
2N
8717.6
60.54
.05058
3
"8902.8
61.83
.05058
3N
9084.0
63.08
.05376
3N
9261 .5
64.32
.05701
3N
9435.4
65.52
.06031
3N
9606.1
66.71
.06368
3N
9773.3
67.87
.06710
3N
9938.0
69.01
.07058
3N
10099.6
70.14
.07412
4
10258.6
71.24
.07771
4N
10568.8
73.39
.08507
4N
10869.5
75.48
.09264
4N
11161.5
77.51
.1004
5
11445.5
79.48
.1084
5N
11722.0
81.40
.1166
5^
11991.5
83.24
.1249
5N
12254.8
85.10
.1335
6
12511.9
86.89
.1422
From Heating and Ventilation, B. F. Sturtevant Co.
583
Digiti
zed by G00gk
584
HEATING
By means of the following table, the duct area in square inches
may be found when the number of minutes for one air change, the
velocity of air in the duct in feet per minute, and the size of the
room are given.
Duct Area, in Square Inches, for 1,000 Cubic Feet of Con-
tents for Given Velocity and Air Change
(B. F. Sturtevant Company)
Number of
Minutes to
Velocity of Air in Duct in Feet per Minute
Change
Air
300
400
500
72.0
600
700
800
900
1,000
1,100
1,200
1,300
1,400
1,500
4
120.0
90.0
60.0
51.6
45.0
40.0
36.0
32.2
30.0
27.6
25.6
21.4
5
96.0
72.2
57.6
48.0
41.1
36.1
32.0
28.8
26.2
24.0
22.2
20.5
19.2
6
80.0
60.0
48.0
40.0
34.3
30.0
26.6
24.0
21.8
20.0
18.5
17.1
16.0
7
68.6
51.4
41.1
34.3
29.4
25.7
22.9
20.6
18.7
17.2
15.7
14.7
13.7
8
60.0
45.0
36.0
30.0
25.8
22.5
23.0
18.0
16.1
15.0
13.8
12.8
12.0
9
53.3
40.0
32.0
26.6
22.9
20.0
17.8
16.0
14.5
13.3
12.3
11.4
10.7
10
48.0
36.0
28.8
24.0
20.6
18.0
16.0
14.4
13.1
12.0
11.1
10.3
9.6
11
43.6
32.2
26.2
21.8
18.7
16.1
14.5
13.1
11.9
10.9
10.1
9.5
8.7
12
40.0
30.0
21.0
20.0
17.2
15.0
13.3
12.0
10.9
10.0
9.2
8.6
8.0
13
36.9
27.7
22.2
18.5
15.7
13.8
12.3
11.1
10.1
9.2
8.5
7.9
7.4
14
34.3
25.7
20.6
17.2
14.7
12.8
11.4
10.3
9.5
8.6
7.9
74
6.9
15
32.0
24.0
19.2
16.0
13.7
12.0
10.7
9.6
8.7
8.0
7.4
6.9
6.4
16
30.0
22.5
18.0
15.0
12.9
11.2
10.0
9.0
8.2
7.5
6.9
6.4
6.0
17
28.2
21.2
16.9
14.1
12.1
10.6
9.4
8.5
7.7
7.0
6.5
6.1
5.6
18
26.6
20.0
16.0
13.3
11.5
10.0
8.9
8.0
7.3
6.6
6.2
5.7
5.3
19
25.3
18.9
15.2
12.6
10.8
9.5
8.4
7.6
6.9
6.3
5.8
5.4
5.1
20
24.0
18.0
14.4
12.0
10.3
9.0
8.0
7.2
6.5
6.0
5.5
5.1
4.8
Thus area of duct in square inches =
contents of room in cubic feet
1,000
X factor in table corresponding to the time of air change and the
desired air velocity. The area can also be found when the air supply
in cubic feet per person (S), number of persons (N) in the room,
and the velocity (V) of the air in feet per minute by the formula,
2.4 S N
V
Laying Out Ventilating Systems. — The location of the fans depends
on the arrangement of the vessel. For instance, if there are a number
of transverse bulkheads which cannot be pierced, then the compart-
ments between these bulkheads must either have a separate system
with its own fan, or there may be a common duct over the bulk-
heads with branches down to the compartments to be ventilated.
Ducts should be close up to the deck beams wherever possible.
In one transatlantic liner the supply ducts extended down the pas-
sageways to the staterooms, discharging air overhead toward the side
JvJ^Vl^
POSITIVE CIRCULATION
585
Pressure and Horse Power Lost by Friction of Air in Pipes
100 Feet Long
Dia.
of
Loss of
Pressure
and Horse
Power
Velocity of Air in Feet per Minute
Pipe
Ins.
1000
1200
1400
1600
1800
2000
2200
2400
2600
2800
3000
12
IS
In. of Water.
Ounces
H.p
In. of water..
Ounces
H.p
.159
.092
.0198
.107
.002
.0297
.229
.133
.0343
.154
.089
.0512
.116
.067
.0685
.091
.053
.0857
.096
.040
.1142
.062
.036
.1256
.057
.033
.1371
.053
.031
.1485
.050
.029
.1599
.047
.027
.1713
.312
.181
.0544
.208
.121
.0816
.157
.091
.1088
.126
.073
.1360
.093
.054
.1814
.085
.049
.1995
.078
.045
.0217
.072
.042
.2360
.067
.039
.2539
.062
.036
.2721
.408
.237
.0812
.273
.158
.1218
.205
.119
.1624
.164
.095
.2031
.122
.071
.2707
.119
.069
.2938
.102
.059
.3249
.095
.055
.3520
.088
.051
.3790
.081
.047
.4061
.517
.300
.1156
.345
.200
.1735
.258
.150
.2313
.207
.120
.2891
.155
.090
.3855
.141
.082
.4240
.129
.075
.4626
.119
.069
.5011
.110
.064
.5406
.104
.060
.5782
.638
.370
.1586
.426
.247
.2380
.319
.185
.3173
.255
.148
.3966
.191
.111
.5288
.174
.101
.5817
.160
.093
.6346
.146
.085
.6874
.136
.079
.7403
.028
.074
.7932
.772
.448
.2111
.516
.299
.3167
.386
.224
.4223
.308
.179
.5279
.231
.134
.7038
.212
.122
.7742
.193
.112
.8446
.178
.103
.9150
.165
.096
.9854
.150
.090
1.1607
.920
.533
.2741
.613
.356
.4112
.460
.267
.5483
.367
.213
.6855
.276
.160
.9138
.250
.145
1.0051
.231
.133
1.0965
.212
.123
1.1879
.205
.119
1.2793
.185
.107
1.3706
1.080
.626
.3485
.719
.417
.5228
.539
.313
.6971
.431
.250
.8714
.324
.188
1.1618
.295
.171
1.2779
.269
.156
1.3941
.248
.144
1.5103
.232
.134
1.6265
.216
.125
1.7427
1.250
.726
.4353
.835
.484
.6530
.626
.363
.8706
.500
.290
1.0884
.376
.218
1.4510
.342
.198
1.5961
.312
.181
1.7412
.289
.168
1.8864
.269
.156
2.0*14
.250
.145
2.1765
1.420
.833
.5354
.959
.556
.8031
24
30
40
44
48
In. of water. .
Ounces
H.p
In. of water. .
Ounces
H.p
In. of water. .
Ounces
H.p
In. of water. .
Ounces
H.p
In. of water..
Ounces
H.p
.079
.046
.0397
.064
.037
.0496
.048
.028
.0661
.043
.025
.0727
.039
.023
.0793
.036
.021
.0859
.034
.020
.0925
.033
.019
.0991
.719
.417
1.0708
.577
.333
1.3388
.431
.250
1.7847
.391
.227
1.9632
.359
.208
2.1416
52
56.
60
In. of water..
Ounces
H.p
In. of water..
Ounces
H.p.
In. of water. .
Ounces
H.p
.331
.192
2.3201
.308
.179
2.4979
.288
.167
2 6771
From Heating and Ventilation, B. F. SturtevanJb Co.
of the ship. Positive circulation throughout a stateroom was
accomplished by extending an exhaust pipe down behind a dressing
case, and providing it at the bottom with a suitable opening. The
stateroom door had a latticed panel, thus giving a ready passage
for the -air.
First prepare deck, inboard profile and cross section plans of the
vessel. Next calculate the amount of air required for each com-
partment. Then locate the fans and sketch on the arrangement plans
the ducts which should be as straight as possible.
At the first outlet make the pressure 5 lb. per sq. ft., and the veloc-
ity about 2,000 cu. ft. per minute. This pressure is for standard
conditions of air with a density corresponding to a barometric height
of 30 ins., a temperature of 70° F., and a relative humidity of 70%. .
Under these conditions a cubic foot of air weighs .07465 lb. The
Digitized by VjOOQLC
686 HEATING
pressure of 5 lb. is equivalent to a pressure head of 67 ft. of air of
standard density. A velocity of 2,000 ft. per minute corresponds
to a velocity head of 17 .27 ft. The total head against which air is
delivered to the supply main is therefore 84.27 ft.*
As the branches lead off, do not change the size of the main until
sufficient air has been removed to reduce the velocity to a value
between 1,200 and 1,500 ft. per minute. Then contract the mains
with a taper of 1 J^ his- to the foot until the area is so reduced that
the velocity again becomes about 2,000 ft. per minute. Repeat the
contraction wherever necessary but do not reduce the final diameter
of the main to less than twice the diameter of the last branch.
Air velocity in feet per minute in a duct =
J * area
Loss of head in a round or square pipe is given by the formula:
HF = 4 F ~ Vf
a
Where H f = loss of head in feet of air due to friction
F = coefficient of friction
L = length of pipe in feet
d = diameter of pipe in feet
Vi = velocity of flow through the pipe in feet per second
If Vi is changed to V or velocity in feet per minute, and taking
the value of F = .00008 for first class piping, the above formula
becomes
LP
Br =
11,250,000 d
Branches should make an angle of about 30° with the main. At
the extreme end of the main, where the velocity is reduced, the angle
may be increased, the last branch leading off at say 90°.
In cargo steamers at least one ventilator is required at each end
of each hold, one serving as the intake and the other as the exhaust.
If the hold is large there are two pairs. If a thorough ventilation
of the cargo is desired, one of the two ventilators should extend to
the bottom of the hold and the other to the deck only, but generally
surface ventilation is sufficient, both ventilators stopping at the deck.
In temperate climates the ventilation is ample if it merely removes
or prevents the formation of heated or vitiated air. In the tropics
it is necessary to have a constant movement of air.
* This and following paragraph from The Naval Constructor, G. Simpson.
Digitized by VJiOOQlC
REFRIGERATION 687
REFRIGERATION
Different substances require different temperatures for their pres-
ervation. Mutton, lamb, rabbits, and some other meats may be
frozen hard and if carefully thawed out when required for use are
apparently not affected. Beef, though it can be frozen and is quite
eatable, when thawed out does not command so high a price as if
merely chilled, that is, reduced to a temperature a little above the
freezing point of the meat. Chilled meat is hung on hooks while
frozen can be stowed in piles; in both cases, however, the meat must
be covered. Juicy fruits, eggs, and vegetables must not be frozen.
Dry still air is the best insulator known and other materials that
are good insulators owe their property very largely to the fact that
they contain a large number of very small air cells. The best
insulating materials for refrigerating rooms are cork, silicate of
cotton or slag wool (obtained from the slag iron melting furnaces),
and finely divided charcoal. See Insulating Materials.
The space taken up by the insulation and the refrigerating machin-
ery in a steamer designed for carrying meat or other perishable
products, is from 18 to 20% of her cubic capacity, that is, the space
available for carrying cargo without the insulation or the refrigerat-
ing machinery being considered.
In the steamer Procida, 3,928 gross tons, insulated capacity of
Spaces 210,000 cu. ft., 2,100 tons of frozen meat carried, carbon
dioxide (CO2) brine circulating system, the insulation was as follows:
"The insulating materials were regranulated cork, sheet cork, and
mineral wool. The ship's side insulation consisted of 3 in. by 3 in.
grounds bolted to the face of the frames and covered by % tongue
and groove boards. The 9-in. space between the boards and the
shell plating was tightly packed with regranulated cork. Over the
%-in. boarding was placed lj^-in. sheet cork with nailing strips,
and the whole covered with waterproof paper and a layer of 1 J^-in.
tongue and groove boards, thus making an over-all thickness of
approximately 12% ins.
" The insulation on the under side of the decks consisted of 6 in. by
2 in. grounds bolted to alternate frames by inch bolts and covered
by %-in. tongue and groove boards. The space between the deck
plating and J^-in. boards was packed with regranulated cork. Be-
low the %-in. boarding was a layer of 1 lA-m. cork with nailing strips,
and the whole covered with waterproof paper and %-in. tongue and
groove boards.
Digiti
zed by G00gk
Cold Storage Temperatures*
(In Degrees Fahrenheit)
Substance
Ale
Apples
Apple and peach butter . . .
Asparagus
Bananas
Beans
Beef (fresh)
Beer in casks
Beer in bottles
Berries (fresh)
Buckwheat flour
Butter
Butterine
Cabbages
Cantaloupes
Carrots
Celery
Cheese
Chestnuts
Cider
Cigars
Clarets
Corn meal
Cranberries
Cream
Cucumbers
Currants
Dates
Eggs.
Ferns
Figs
Fish (fresh)
Fish (frozen)
Fish (canned)
Fish (dried)
Fish (to freeze)
Flour
Fruits
Fruits (dried)
Fruits (canned)
Furs (dressed)
Furs (undressed)
Grapes
Ginger ale
Hams
Hogs
Hops
Fahrenheit
33-42
32-36
40
33-35
34-35
32-40
35-39
32-42
45
35-40
40-42
14-38
20-35
32-35
40
33-35
32-35
28-35
33-40
32-40
35-42
45-50
42
32-36
35
38-40
32
45-55
30-35
28
35-55
20-30
14-17
35
35-40
5
36-46
26-55
35-40
30-35
25-32
35
32-40
35-36
20*35
30-35
32-40
Substance
Hops (frozen) ,
Honey '.
Lard
Lemons
Liver
Maple syrup and sugar
Margarine
Meat (brined) ,
Meat (canned)
Meat (fresh)
Melons
Milk
Mutton
Mutton (frozen)
Nuts in shell
Oatmeal
Oleomargarine ,
Oil
Onions
Oysters in tubs
Oysters in shells
Oxtails :
Parsnips
Peaches
Pears
Plums
Porter
Pork
Potatoes ,
Poultry (frozen)
Poultry (to freeze)
Poultry (long storage)
Sardines
Sauerkraut
Sausage casings
Sugar
Syrup ,
Tenderloin
Tomatoes ,
Tobacco
Veal ,
Vegetables ,
Watermelons
Wheat flour
Wines
Woolens
Degrees
Fahrenheit
28
36-45
34-35
33-45
30
40-45
18-35
35-40
30-35
34-40
35
32
33-36
25-28
35-40
40-42
20-35
35-45
32-40
25-35
33-43
32
32-35
34-55
40-45
32-40
33-42
34
34-40
20-40
5-22
10
35-40
35-38
30-35
40-45
35-45
30-35
32-42
35-42
32-36
34-40
34-40
40-42
40-50
25-35
* Sanitary Refrigeration and Ice Making, J. J. Cosgrove.
588
Figure 95. — Layout of a Refrigerating Plant.
(Brunswick Refrigerating Co., New Brunswick, N. J.)
589
590
HEATING
Digiti
zed by G00gk
'"*" COMPRESSION SYSTEM 591
"The margin plates of decks and bulkheads were insulated by a
heavy hard wood ribband, fitted and bolted watertight to the top
side of the margin plate at 4 ft. from the shell, carrying 2-in. tongue
and groove boarding fastened to the ship's side insulation. The
space between the 2-in. boarding and the deck was packed with sheet
cork and grouted in with a plastic mixture of granulated cork and
pitch.
"The insulation in way of beam knees was left portable for easy
renewal of insulation filling in case of settlement. The bulkheads
were insulated, the boiler and engine room bulkheads being insulated
with mineral wool to minimize the danger of fire. The insulated
limber hatches extended the whole length of the bilges. They had
frames and coamings working from solid timbers. Each hatch
section was 6 ft. long and had two lifting rings. All the steel work
was galvanized.
"To prevent the meat from coming in contact with the cold pipes
on the ceilings, bulkheads, and sides, wood gratings were attached
to the pipe supports by lag screws, and arranged to allow an unre-
stricted air circulation about the pipes." *
For the ventilating of refrigerating rooms the plenum or forced
draft system is preferable to the induced. As to the quantities
of air required, authorities differ. Some say that an introduction of a
volume of air equal to that of the room should take place every day,
while others say twice a day. The outlet for the escape of the foul
air should be near the floor and the inlet near the ceiling. Below
are outlined different refrigerating systems.
Compression System. — Here the refrigerating process takes place
during the transformation of ammonia from a liquid to a gas, and is
accomplished by allowing the liquid, compressed to 150 to 170 lb., to
pass through a special valve known as the expansion valve to the
expansion piping or brine coolers in which a much lower pressure
is maintained.
The ammonia tends to vaporize at the lower pressure, but in order
to do so it must be supplied with a certain amount of heatrnamely,
its latent heat of vaporization. The heat is absorbed from the
surrounding sujbstances by the ammonia in its passage through the
piping or coolers after leaving the expansion valve. Through the
expansion side of the plant the now vaporized ammonia returns to
the compressor, is retompressed and forced through a condenser
where the latent heat is absorbed. From the condenser the ammonia
* Data on Procida from International Marine Engineering, June, 1916.
Digiti
zed by G00gk
592
HEATING
oooooooo
g
3
•c
«
Digiti
zed by GoOgk
EXPANSION 593
flows to the receiving tank and from there to the expansion valve
to commence again its cycle.
The expansion takes place either in the piping that is in direct
communication with the substance to be cooled or in coolers sub-
merged in a solution of brine. In the latter case, the brine is reduced
to a very low temperature, and by means of a pump is circulated
through the piping in the refrigerators or tanks. These two systems
are known as the direct expansion and brine circulating respectively,
and are shown in Figs. 96 and 97. The former is generally for small
units and its chief advantages are simplicity, economy, ease of
operation, and compactness.
The liquid ammonia stored in the receiver R (see Fig. 96), passes
through the expansion valve X into the coils or piping located
in the compartment to be cooled E, and after expanding returns
to the compressor C where it is compressed and forced through
the oil separator S to the condenser W. In W the ammonia is
condensed by water circulation, and returned in liquid form to the
receiver R.
In the brine circulating system the ammonia expands in pipes
submerged in a brine tank as shown in Fig. 97, or in a cooler designed
for the purpose and in conjunction with a smaller tank. The brine,
cooled to a low temperature by the ammonia in the expansion piping
or cooler, is pumped through the piping in the refrigerating com-
partment.
When it is desired to shut down the plant for a few hours daily,
the brine tank is made sufficiently large for the storage of the cold
brine, the temperature being maintained, when the compressor is
shut down, by continuing the circulation with the pump.
The brine circulating system is recommended in large installations
where the various compartments to be cooled are widely scattered.
On account of the additional apparatus such as tank, cooler, pump,
etc., more room is required, but the temperatures in the various
compartments can be regulated more easily and uniformly.
The brine flows through the coils at the rate of about 3 ft. per
second and is kept at a temperature 8° to 10° lower than that re-
quired in the chamber. For instance, if fruit is to be maintained at
30°, then the brine should be about 22°. The difference in tempera-
ture between the outgoing and return brine should be from 3° to 5°.
A temperature of 10° requires double the length of pipe necessary
for a temperature of 32°. Brine containing 25% chloride of calcium
has been found satisfactory for ordinary marine use.
Digitized by VjiOOQ 1C
594 HEATING
Plants operating on the ammonia compression system are built
by the Brunswick Refrigerating Co., New Brunswick, N. J., in* >£-,
1-, 2-, 4-, 6-, 8-, 12- and 15-ton sizes.
In the system's just outlined ammonia is the refrigerant but instead
carbonic anhydride (also known as carbon dioxide and carbonic acid,
CO2) could have been. The greatest drawback to CO2 is the high
pressure necessary, ranging from 200 to 1,000 lb. per square inch,
while ammonia at a gauge pressure slightly above 15 lb. can be lique-
fied at a temperature of 0° F. Ammonia, if it escapes, has the disad-
vantage of affecting meat or other food products it comes in contact
with, although CO2 does not. CO2 will not act on copper or iron
pipes.
Owing to the lower temperature and greater rapidity of circulation
of ammonia gas, less pipe surface is necessary in a direct expansion
ammonia coil to produce a given refrigeration effect than would be
required in a brine coil.
It is to be noted that the higher the sea temperature the higher the
pressure required in the compressor. Ammonia (NH3) evaporates
at — 28° F. when the pressure is 14.7 lb. (atmospheric), and has a
latent heat of evaporation of 555 B. t. u. Carbonic anhydride evap-
orates at — 110° when the pressure is 14 .7 lb., and has a latent heat
of evaporation of 130 B. t. u.
The following is a description of apparatus using CO2 as built by
J. & E. Hall, Ltd., of Dartford, Eng. The apparatus consists of
three parts, viz., a compressor, a condenser, and an evaporator. The
compressor draws in heated and expanded gas from the evaporator
and compresses it. The compressed gas then passes to a condenser
consisting of coils in which the warm compressed gas is cooled and
liquefied by reduction of temperature caused by the action of the
cooling sea water. From the condenser the cool liquid carbonic
anhydride is conveyed into the evaporator consisting of coils, where
it vaporizes and expands, absorbing heat in the process and cooling
the surrounding brine which is in contact with the coils. This cold
brine is circulated by a small pump to the refrigerating chamber
where it is conducted through a long series of rows of cooling pipes
termed grids, which are placed at the top of the chamber. The cold
brine grids in this position set up a circulation of air, the cold
air descending and being replaced by air not so cold which is cooled
in its turn. Any moisture in the air is condensed on the grids and
appears as frost on the pipes. The CO2 is supplied in steel cylinders.
The compressor may be either horizontal or vertical, and driven
Digitized by VjUDV LVL
COOLING BY AIR
595
either by a steam cylinder or by an electric motor. Modern war
vessels often have installed electrically driven machines which have
the advantage that they can be conveniently arranged in positions
in which steam-driven cannot be. Thus the cooling units in a battle-
ship may be placed close to the magazines they are to cool, avoiding
the loss of cold from the transmission of low temperature brine
through long length of pipe.
Below is a list of Kroeschell Bros.' (Chicago, 111.) horizontal double-
acting C02 compressors, with their refrigerating capacity.
Refrigerating Capacity
Ice Making Capacity
of Machine in 24 Hours
of Machine in 24 Hours
Horse Power Required
Tons
Tons
3
1.5
6
5
2.5
9
8
4
13
10
5
15
12
6
17
16
8
22
20
10
26
25
12.5
32
35
17.5
43
• 40
20
48
50
25
60
60
30
72
70
35
84
80
40
96
90
45
108
100
50
120
120
60
140
One ton of refrigeration is the amount of cooling done by the
melting of one ton of ice at 32° F. into 1 ton of water at 32° F. This
is equivalent to 284,000 B. t. u. The power in the above table is
based on condensing water having a temperature of 70°.
Cooling by Air. — The Allen dense air machine (built by H. G.
Roelker, New Y6rk City) produces cold by the expansion of air
which has previously been compressed and then cooled by water. It
uses air of about 65 lb. pressure and compresses it to approximately
235 lb., then cools it by passing it through a coil immersed in water;
then an expanding engine brings the air back to 65 lb. and to a very
low temperature. This cold air goes to the coils in the refrigerating
room and after passing through them returns to the suction side of
Digitized by VJiOOQlC
596
HEATING
the air compressor, where it is again compressed and the cycle just
outlined is gone through again. The machines are built in }£-, 1-,
2- and 3-ton sizes.
Figure 98. — Allen Dense Air Machine.
A practical rule for the square feet of refrigerating pipe required
in a meat chamber to keep it at the freezing point is 1 sq. ft. of pipe
surface for every Vyi to 2% sq. ft. of interior surface of a well insu-
lated meat chamber, omitting interior divisions. The piping should
be so arranged that the air is compelled to pass all surfaces with a
fair velocity.
Pipe, Valves, and Fittings for refrigerant piping are different from
steam and water. If the refrigerant is ammonia, no brass enters
into the design of any part of the valves and fittings. The operating
principles of the valves are the same as for steam and water but they
are made heavier and entirely of iron, or iron and aluminum.
On account of the high pressure under which refrigerating plants
operate, extra strong wrought iron pipe is used for ammonia and
double extra strong for CO2. Ordinary steam and water fittings are
suitable for brine circulation.
See also section on Piping.
Linear Feet of Pipe Required. — For direct cooling coils where
the pipe surface is simply exposed to the air of the room to be
cooled, Lorenz recommends a transmission allowance of not over
30 B. t. u. per square foot per hour. For an average room tem-
perature of 30° and average brine temperature of 10°, this would
30
correspond to ~ = 1.5 B. t. u. transmitted per square foot per hour
per degree difference.
Digiti
zed by G00gk
AMMONIA COMPRESSORS 597
Example. How many linear feet of lK-inch direct refrigerating coils would be
required to keep a cold storage room at 30° if the refrigeration loss is 8,000 B. t. u.
per hour and the temperatures of the brine entering and leaving the coils are 10°
and 20° respectively? Average brine temperature 15° and a transmission con-
stant of 1.5 allowed.
, -. , . A. Total B. t. u. lost
Square feet of refrigeration = ; , /rr> : — r; : , . , .
1.5 (Temp, inside pipe— temp, outside)
8,000
1.5(15-30)
355 sq. ft.
Circumference of 1^-inch pipe — 5.2 ins., hence 1 ft. of pipe has an area of
5.2 X 12 = 62.4 sq. ins. or .43 sq. ft.
355
Then — — ' = 825. ft. (nearly) of 1M ins. pipe required.
[Above from Cold Storage, Heating and Ventilating, S. F. Walker.]
Capacity of Ammonia Compressors. — The refrigerating capacity
of a compressor depends on the number of pounds of gas it will
handle in a given unit of time. The weight of ammonia gas handled
depends upon the efficiency of the compressor and upon the suction
pressure or the pressure at which the gas is delivered into the com-
pressor.
Since the weight of ammonia gas varies approximately as the
absolute pressure, it follows that the refrigerating capacity of a
compressor varies with the absolute suction (or back) pressure.
Thus a compressor working under a suction pressure of 30 lb.
(gauge pressure) will have approximately 50% greater capacity
than one working under 15 lb. gauge pressure, but the same low
temperature cannot be obtained.
To determine the refrigerating effect produced by the evapora-
tion of one pound of liquid ammonia at a given back pressure, a
deduction must be made from the latent heat of evaporation at that
pressure for the work required to cool the ammonia itself, from the
temperature at which it enters the evaporating coils to the tem-
perature at which the evaporation takes place. The temperature
at which the ammonia enters the evaporating coils should be ap-
proximately that of the water used for condensing purposes.
The table given below shows the number of cubic feet of gas
that must be pumped per minute at different suction and con-
densing pressures to produce one ton of refrigeration in 24 hours.
The values given are theoretical ones; it is assumed that the tem-
perature of the ammonia entering the evaporating coils corresponds
to the temperature of condensation at the pressures given, and no
allowance is made for unavoidable losses.
Digitized by VJiOOQLC
598
HEATING
Number op Cubic Feet op Gas
That must be pumped per minute at different condenser and suction
pressures to produce one ton of refrigeration in 24 hours
00
Temperature of the Gas in Degrees F.
3 ao
|| &
65
70
75
80
85
90
95
100
105
Corresponding Condenser Pressure (gauge) lb. per Sq. In.
s
H
1 C 1,1
\\r*
127
189
153
1GB
181
200
218
G. P.
-27
1
7.22
7.3
7.37
7.46
7.54
7.62
7.70
7.79
7.88
-20
4
5.84
5.9
3.96
6.03
6.09
6.16
6.23
6.30
6.43
-15
6
5.35
5.4 -
5.46
5.52
5.58
5.64
5.70
5.77
5.83
-10
9
4.66
4.73
4.76
4.81
4.86
4.91
4.97
5 05
5.08
- 5
13
4.09
4.12
4.17
4.21
4.25
4.30
4.35
4.40
4.44
0
16
3.59
3.63
3.66
3.70
3.74
3.78
3.83
3.87
3.91
5
20
3.20
3.24
3.27
3.30
3.34
3.38
3.41
3.45
3.49
10
24
2.87
2.91
2.93
2.96
2.99
3.02
3.06
3.09
3.12
15
28
2.59
2.61
2.65
2.68
2.71
2.73
2.76
2.80
2.82
20
33
2.31
2.34
2.36
2.38
2.41
2.44
2.46
2.49
2.51
25
39
2.06
2.08
2.10
2.12
2.15
2.17
2.20
2.22
2.24
30
45
1.85
1.87
1.89
1.91
1.93
1.95
1.97
2.00
2.01
35
51
1.70
1.72
1.74
1.76
1.77
1.79
1.81
1.83
1.85
Crane Co., Chicago.
. To obtain the net refrigerating effect of a compressor it is neces-
sary to determine: (1) the suction or back pressure, (2) the tem-
perature at which the ammonia enters the refrigerating coils,
(3) the percentage of allowance to cover unavoidable losses.
"In the operation of a plant it has been found that the following
conditions represent a fairly average practice : back or suction pres-
sure 15.67 lb. above atmosphere (at which pressure ammonia
evaporates at 0° F.); condensing water at 60° F., which gives am-
monia liquid a temperature of about 65° F. Under these conditions
it requires the handling of about 7,500 cu. ins. of gas per minute
to produce the effect equal to the melting of one ton of ice in 24 hours.
Refrigeration Required for the Cold Storage Room.* — To find the
number of British thermal units to be withdrawn to maintain a
constant temperature in a storage room, multiply the area of the
floor, walls, and ceiling in square feet by the constant 3, and the
product by the number of degrees the rooms are to be lowered in
temperature.
* From Sanitary Refrigeration and Ice Making, J. J. Cosgrove.
Digitized by VjiOOQIC
STORED GOODS 599
Let H = number of B. t. u. of refrigeration effort required
A = area of floor, walls and ceiling in square feet
T = temperature of adjoining compartments or outside air
t = temperature to be maintained in cold storage room
3 = a constant for leakage of heat through the walls
Then H = 3 A (T - t)
Example. How many British thermal units of refrigeration will be required
a cold storage room 40 ft. by 50 ft. by 12 ft. high, to keep it at a temperature
35° F. when the outside temperature is 70° F.
Area of wall - [40 + 40 + 50 + 50] X 12 = 2160
Area of floor and ceiling = 40 X 50 X 2 = 4000
Total square feet 6160
Temperature outside, 70° F.
Temperature inside, 35°
Difference 35°
Substituting in formula H=SA(T— t) =3 X 6160 (70° — 35°) = 646,800 B. t. u.
There are 284,000 B. t. u. to one ton of refrigeration; hence to reduce British
thermal units to tons divide 646,800 by 284,000 = 2 . 27 tons.
An empirical formula is to allow one ton of refrigeration to
2,000 cu. ft. of space for small installations, but more is required
for large.
Refrigeration Required to Cool Stored Goods.*— Multiply the
weight of the goods by their specific heats and the product by the
difference between the ordinary heat of the stored goods and tem-
perature of storage room.
Let H = number of British thermal units of refrigeration effort
required
W = weight of stored goods
S = specific heat of stored goods
T = temperature of goods when put in storage
t = temperature of cold storage room
H = W S (T - t)
When several kinds of goods are stored, each having a different
specific heat, then the sum of all their weights and specific heats
is required and the formula is H = W S (T - t) + Wi Si (T - t),
etc., where W S, Wi Si, etc., refer to different goods, as W S would
equal the weight times the specific heat of beef, Wi Si the weight
times the specific heat of pork, etc.
Example. Find the refrigeration required to cool 25,000 lb. of lean beef from a
temperature of 95° F. to 35° F.
From the table of Specific Heats the specific heat of beef above the freezing point
is . 77, and the difference in temperature between 95° and 35° = 60°. Substituting
these values in the formula,
H = W S (T - t) = 25,000 X .77 X 60 = 1,155,000 B. t. u.
Dividing 1,155,000 by 284,000 (the number of B. t.u. in a ton of
Digitized by
lL .. . ... , 1,155,000 . __ x
the quotient will be ' =4.06 tons.
600 HEATING
Specific Heat and Latent Heat op Various Food Products
Composition
Specific
Heat Above
Specific
Heat Below
Freezing in
Heat Units
Latent
Heat of
Substance
Water
Solids
Freezing in
Heat Units
Freezing in
Heat Units
Lean beef. . . .
Fat beef
Veal
72.
51.
63.
39.
70.
74.
91.
83.
59.25
87.50
80.38
78.
62.07
76.62
72.40
73.70
28.
49.
37.
61.
30.
26.
9.
17.
30.75
12.50
19.62
22.
37.93
23.38
27.60
26.30
0.77
.60
.70
.51
.76
.80
.93
.87
.68
.90
.84
.82
.69
.81
.78
.80
0.41
.34
.39
.30
.40
.42
.48
.45
.38
.47
.44
.43
.38
.42
.41
.42
102
72
90
Fat pork
Eggs
Potatoes
Cabbage
Carrots
Cream
Milk
Oysters
Whitefish
Eels •
55
100
105
129
118
84
124
114
111
88
Lobster
Pigeon
Chicken
108
102
105
The specific heat of a substance is the ratio of the heat required to raise the
temperature of a certain weight of, the substance one degree Fahrenheit, to that
required to raise the temperature of the same weight of water one degree. As the
specific heat is not constant at all temperatures it is generally assumed that it is
determined by raising the temperature from 62° to 63° F. For most substances it
is practically constant for temperatures up to 212° F.
Horse Power required.
I. h. p. of engine for steam-driven compressor = 1.4X rating
of ice machine in tons of refrigeration per 24 hours,
or
I. h. p. = 2.8 X rating of machine in tons of ice per 24 hours.
Three tons of coal per 24 hours were required to operate the
refrigerating plant of the steamer Procida (see page 587).
Operating and Miscellaneous Notes. — Refrigerating machines
are rated in two ways, viz., ice-making capacity or tons of ice they
will produce in one day of 24 hours, and refrigerating capacity or
cooling done by one ton of ice melting per day of 24 hours. Thus
a machine which, if operated 24 hours a day, will do the work of
the melting of one ton of ice in 24 hours is called a one-ton machine.
Roughly, the ice-making capacity is about one-half of the refriger-
^g capacity.
Digitized by VJiOOQLC
DRAINAGE SYSTEM % 601
The power required for refrigerating machinery varies from
2. h. p. per ton of refrigeration up to 5. h. p.
Meat and other products must not be handled any more than
can possibly be helped. In many instances when frozen sheep
are brought from New Zealand to England, each is inclosed in a
linen bag.
The Rules of the Board of Trade (British) require that machines
using ammonia and other poisonous gases shall be placed in an iso-
lated and well ventilated space entirely apart from the engine room
or other part of the vessel to which the crew or passengers have
free access, whereas a C02 refrigerating machine may be and is
frequently erected in the main engine room.
For the cooling effect it is necessary that a difference of tem-
perature should exist between the gas in the condenser coils and
the circulating sea water, the latter having the lower temperature
so that the excess heat picked up by the refrigerant from the brine
in the evaporator may be transferred to the circulating water and
so carried overboard.
If the sea water rises to a temperature of say 80° F.,. then the
temperature of the ammonia or C02 must be in excess of this by
8° or 10° to allow of heat transfer, and to obtain this difference
of temperature the pressure of the gas must be increased in due
proportion.
For a gas temperature of 90° the ammonia pressure should be
about 180 lb. and the C02 pressure 1,140 lb., and if the sea tem-
perature rises to 85° and the gas temperature is to be say 93°, the
ammonia pressure would need to be 200 lb. and the CO21 1,180 lb.
per square inch, so that the higher the sea temperature the higher
the pressure required in the compressor to maintain the necessary
difference in temperature.
Costs, see Prices, Costs and Estimates.
DRAINAGE SYSTEM
For removing the water that collects in the bilges from the
sweating of the hull and other causes, a drainage system is neces-
sary. In motor boats and other small craft a portable pump
with a rubber suction pipe is all that is required. In larger vessels
the pump is permanently fastened to the deck with pipes leading
to the bilge. In both cases the pumps are hand operated.
For vessels say 120 ft. or over there is required a steam-driven
pump, and often other pumps, as the donkey, are connected to the
Digitized by VjiOOQ 1C
r
602 HEATING
•
drainage system* The piping generally consists of a main drain
between the engine and boiler rooms and an auxiliary drain running
fore and aft with branches to the different compartments, or a pipe
to each compartment, the pipes being connected to a common
manifold. — ^^^j^^— „.-^ .
i. All suction pipes must have perforated nozzles at their ends
or lead into strainers to prevent cotton waste and other materials
from being drawn into the pump.
Main Drain. — This consists of a large pipe from the forward
boiler room to the engine room bilge with an opening to each boiler
room fitted with a sluice valve and a non-return check valve. In
the engine room bulkhead are also sluice valves.
If the boiler room is flooded and it is desired to pump it out,
it is only necessary to open the sluice valve from the flooded boiler
room to the main drain and the sluice valve at the engine room
bulkhead and to start up the drain pump. Care must be taken
that no water is allowed to drain into the engine room bilges that
cannot be handled by the pump. -—- - ■ •— --
Drain pipes may be installed at the forward end of the ship,
the pipes discharging into the forward boiler room bilge, and sim-
ilar pipes installed at the after end discharging into the engine
room bilges. Sluice valves are fitted to the pipes at the boiler and
engine room bulkheads, screw-down valves at the other main bulk-
heads, and screw-down non-return valves at the end of each branch.
Auxiliary Drain. — Besides the main there is an auxiliary drain
of about 6 ins. in moderate size vessels and 10 or 12 ins. in large size
vessels, that extends fore and aft along the tank top. It is connected
to the fire and bilge pumps and the hand pumps, and has branches
to the various compartments including the double bottom. Com-
partments, as the wing spaces which have no branches to the aux-
iliary drain, are drained to adjacent compartments by sluice valves
which should be arranged so as to be operated from above the water
line. *~»p — ?
The auxiliary drain has screw-down valves at each main bulk-
head, screw-down non-return valves to the branches to the com-
partments, and similar valves to the double bottom. To pump
out any compartment to which a branch leads, open the valve at
the end of the branch, all the bulkhead valves on the main suction
between the compartment and the pump it is desired to use, the
valve between the pump and the main suction, and the valve be-
tween the pump and the discharge overboard. It is accessary that
y Google
LLOYD'S RULES
603
all the valves on the other branches shall be tightly shut; otherwise
the pump would draw air through them.
Instead of an auxiliary drain as above, pipes may be run to
every compartment, all the pipes being connected to a common
manifold usually located in the engine room. This manifold in
turn is connected to the drain pump and to other pumps, as the
donkey. With this arrangement any compartment can be drained
entirely independent of any other, which is preferable to a large
auxiliary drain with branches.
Notes. — The U. S. Steamboat-Inspection Rules (1916) state:
"Each and every steam vessel shall be fitted with a bilge pipe
leading from each compartment and connecting with a suitable
marked valve to the main bilge pump in the engine room, and each
compartment of all steam vessels shall be fitted with suitable sound-
ing pipe, the opening of which shall be accessible at all times, except
that in compartments accessible at all times for examination no
sounding tubes are necessary. Steam siphons may be substituted
in each compartment for the bilge pipes.' '
Figure 99. — Draining by Bilge Ejector.'
Lloyd's Rules state: "A bilge injection or a bilge suction to
the circulating pump is to be fitted. The engine bilge pumps are
to be fitted capable of pumping from each compartment of the
vessel, the peaks excepted. All bilge suction pipes are to be fitted
with strum boxes or strainers, so constructed that they can be
cleared without breaking the joints of the suction pipes. The
total area of the perforations in the strainers should be not less than
y Google
604 HEATING
double that of the cross-section of the suction pipe. The mud
boxes and roses in the engine room are to be placed where they
are easily accessible.
"Hold with Double Bottoms. — In the double bottom of each
compartment of the holds and of the engine and boiler spaces a
steam pump suction is to be fitted at the middle line, and one on
each side to clear the tanks of water when the vessel has a heavy list.
"Where there is a considerable rise of floor towards the ends
of vessels, the middle line suction only will be required. A steam
pump suction and a hand pump are also to be fitted to each bilge
in each hold where there is no well. Where there is a well one
or three steam pump suctions are to be fitted in the same accord-
ing as there is considerable or little rise of floor, and hand pump
suctions are to be fitted at the bilges.
"Holds without Double Bottoms. — Where there is considerable
rise of floor, one steam pump suction and one hand pump are to
be fitted in each hold. Where there is little rise of floor 2 or 3
steam pump suctions and at least one hand pump suction are to
be fitted to each hold.
"Engine and Boiler Space. — Where a double bottom extends the
whole length of the engine and boiler space, 2 steam pump suctions
are to be fitted to the bilge on each side. Where there is a well,
one steam pump suction should be fitted in each bilge and one in
the well. Where there is no double bottom in the machinery
space center and wing steam pump suctions should be fitted.
The rose box or strum of the bilge injection is to be fitted where
easily accessible. The main engine bilge pump and the donkey
pump are to be arranged to draw from all compartments, and
the donkey pump is to have a separate bilge suction in the engine
room which can be used at the same time as the main engine bilge
pumps are drawing from any part of the vessel.
"Fore and After Peaks. — If the peaks are fitted as water ballast
tanks, a separate steam pump suction is to be led to each. If not
used for water ballast an efficient pump is to be fitted in the fore
peak. If the after peak is used as a ballast tank, no sluice valve
or cock is to be fitted to the after bulkhead, but if it is not so used,
and if no pump is fitted in it a sluice valve or cock is to be fitted
to the after bulkhead to allow water to reach the pumps when
required.
"Tunnel. — The tunnel well is to be fitted with a steam pump
suction.
Digiti
zed by GoOgle
HAND PUMPS
605
"All Hand Pumps are to be capable of being worked from the
upper or main decks or above the load water line, the bottoms of
the pump chambers are not to be more than 24 ft. above the suction
rose and the pumps are to be tested by the surveyors to ensure
that water can be pumped from the Umbers. The sizes of the hand
pumps are to be not less than those in the following table:
Hand Pumps in Holds
Tonnage Under Upper Deck
Dia. of
Barrel, Ins.
Dia. of Tail
Pipe, Ins.
In vessels not exceeding 500 tons
4
5
5A
2
Above 500 tons but not exceeding 1,000 tons.
Above 1 ,000 tons but not exceeding 2,000 tons.
Above 2,000 tons
2Ji
2M
"In lieu of hand pumps in each compartment an approved fly-
wheel pump may be fitted if it is connected to the steam pump
.bilge suction pipes of these compartments.
"The hand pumps may be dispensed with in vessels which have
2 independent boiler rooms, or a donkey boiler above the bulkhead
deck, and steam pumps (workable from either source of steam)
in 2 separate compartments connected to the suctions.
"The bilge injection should not be less than two-thirds of the
diameter of the sea inlet to the circulating pump. The inside
diameter of other bilge suction pipes should not be less than those
below:
Tonnage Undjr Upper Deck
Sa1§
fl si &'£
<u ^ _. o
2 =*.£
•a a is
a-? ° °
Wing Suction in Holds
Where no Center
Suctions are Fitted
and Wing Suctions
in Engine Room
S iH
wJJ
.d fcw
"oo i °
a ef-3
ft-
In vessels not exceeding 500 tons
Inches
2
2M
2A
3
SA
3A
Inches
2
2
2H
3
3^
Inches
2
Above 500 but not exceeding 1,000 tons. .
Above 1,000 but not exceeding 1,500 tons.
Above 1,500 but not exceeding 2,000 tons .
Above 2,000 but not exceeding 3,000 tons .
Above 3,000 tons
2
2
2V2
2Va
606 HEATING
"In cases where more than one suction to any one compartment
are connected to the pumps by a single pipe, this pipe should be
not less than the size required for the center suction."
As the frequent thumpings of a sounding rod are likely to damage
the plating below it, a small doubling plate should be riveted under
each rod.
A sluice valve should never be fitted to the collision bulkhead,
nor should one be fitted to a watertight bulkhead unless the valve
is readily accessible at all times.
In warships the wings and coal bunkers are drained on to the
inner bottom, in which are pockets formed to catch the water,
the pockets being pumped out by branches from the main suction
and from the fire and bilge pumps. The double bottom spaces
are drained from one to the other through drain holes cut in the non-
watertight longitudinals, and sluice valves are fitted on the water-
tight longitudinals. To allow the air to escape from the double
bottom compartments while they are being filled with water, escape
pipes are fitted at the top of each compartment.
PLUMBING
Under this heading are included all pipes and fittings connected
to lavatories or conveying fresh water for drinking purposes.
Fixtures. — Fittings on the hull through which salt water is drawn
should have a perforated plate at the outboard end to prevent
sticks and other foreign matter being drawn in. The connection
between the hull and the suction of the pump should be of
copper.
For motor boats and small yachts a wash stand with a tank on
top, or a pitcher nearby, serves to hold the fresh water, the dis-
charge from the basin running into a pail below. Others are made
so as to fold up, thus taking up a minimum amount of room. Some
have hand pumps which draw the water from the fresh water
tanks; others have faucets, thus requiring the water to be under
pressure.
Either of two types of bathtubs may be installed, viz. Roman,
which slopes at both ends and usually has the connections at the
back, and the French, which slopes at one end only. The former
is adapted for placing along a wall away from corners, while
the latter is for corners. The best grade is made of porcelain or
earthenware lined with enamel; the second, cast iron painted or
Digitized by VjOOQ IC
SINKS 607
lined with porcelain enamel; and the cheapest, tinned sheet copper
lining over a cast iron base. Sizes about 5 ft. long, 2 ft. 5 ins. wide
by 2 ft. high.
Sinks for kitchen and pantry should have little wood work around
them, and are deeper than shore outfits. The kitchen sinks are
of cast iron or sheet metal and the pantry of copper.
Figure 100.— Closet. (J. L. Mott Co., New York.)
Closets. These may be divided into (1) syphon jet, washdown
and washout and (2) pump closets. In the former (1) it is necessary
to supply the closet with water by a direct pressure system (com-
pressed air or steam operated ejector) or a tank for a gravity supply.
In the latter (2) by working a pump, the discharge is forced out.
Closets with a pressure discharge are usually installed on large ves-
sels,— one maker advises that he has furnished more syphon closets
than washout, and another maker recommends that on ocean
steamers the washdown bowl be used instead of the washout.
Pump closets are for small yachts and motor boats. The inlet for
the water should be below the discharge and over the inlet at the
side is a perforated plate. When the closet is set so the top of the
bowl is below the water line, the discharge pipe should have its
highest point at least 6 ins. above the water line, for by so doing
flooding is prevented should any obstruction become lodged under
the valve. In large vessels the closets may be flushed by water
from overhead tanks, requiring a complete salt water flushing
Digitized by VjOOQ 1C
60S
HEATING
Digiti
zed by G00gk
WASTE LINES 609
system with a sanitary pump. Closet bowls should have a back
water check valve.
Waste lines should be of galvanized iron pipe or lead pipe
with brass clean out plugs at the bends. As far as practicable
the discharge from each fixture in the toilets and bathrooms should
be separately trapped and have a separate branch to the discharge
pipe. The number of discharge pipes should be kept at a minimum
to reduce the number of openings in the shell plating, the open-
ings being just above the load water line, and having at the lower
end a flap valve. Where possible, the waste from bathtubs, lava-
tories, and shower baths should connect with the deck scuppers,
but in no case should the drains from the water-closets and sinks
connect with the scuppers.
For discharging soil from baths, urinals, etc., a water jet eductor
may be used as shown in Fig. 101. The pressure water is brought
to the eductor through the pipe PWf and the various drains and
soil pipes connected to pipe S. To start the eductor all that is
necessary to do is to turn on the pressure water. The pressure in
pounds per square inch at the eductor, when in operation, should
not be less than 214 times the elevation in feet. Thus for an
elevation of 10 ft., there should be a pressure of 25 lbs. Fig. 101
is from Schutte & Koerting, Philadelphia.
Fresh Water Service. — This consists of pipes to the fresh water
tanks and pumps for drawing from same and discharging into the
fresh water system with branches to drinking stands and to lava-
tories. The faucets at the lavatories and drinking stands should
be automatically closing to prevent waste of water. A strainer
should be fitted in the suction pipe close to the pump, the pump
maintaining a constant pressure in the system, by means of a
governor valve set at 20 to 50 lbs. according to the size of the
vessel. The pressure line should also have a connection through
a safety valve to the suction of the fresh water pump, which carries
off the surplus water.
For supplying hot fresh water, Ashwell & Nesbit, Leicester,
Eng., install copper heaters supplemented by a large copper storage
cylinder. The water is heated in the heaters by steam and is
circulated by mechanical means, continually flowing out of the
storage cylinder around the ship and returning to the heaters again.
Each draw-off has thus an immediate supply of hot water when a
faucet is opened, and there is no waste due to drawing off a large
volume of tepid water before hot water is available.
Digitized by LiOOQ 1C
610
HEATING
Or instead of the above there may be calorifiers located in differ-
ent parts of the ship. As built by A. Low & Sons, Glasgow, they
consist of a casing in which is steam surrounding the water to be
heated. No steam trap is required as the calorifiers are designed
in such a way as to condense all the steam supply, and when fitted
with an automatic control valve one may supply several baths
or basins. They are made of copper and brass, and may be silver
or nickel plated. The table given below contains data from actual
tests.
Size of Calorifier
Size of
Steam
Connection
Ins.
Gallons
per Minute Heated to 100° F.
Steam Pressure
Diameter
Ins.
Length
Ins.
65 Lb.
50 Lb.
30 Lb.
20 Lb.
12
12
16^
19
21 H
3
5
H
a
13 J*
38
45
4
8
11
30
35
2M
6
2oy2
25
2
15Ji
20
FIRE EXTINGUISfflNG AND ALARM SYSTEMS
General Requirements. — Every steamer permitted by her cer-
tificate of inspection to carry as many as 50 passengers or upward,
and every steamer carrying passengers which also carries cotton,
hay, or hemp, shall be provided with a good double-acting steam
fire pump, or other equivalent apparatus for throwing water. Such
pump or other apparatus shall be kept at all times in good order,
having at least two pipes of suitable dimensions, one on each side
of the vessel, to convey the water to the upper decks, to which pipes
there shall be attached by means of stop cocks or valves, both be-
tween decks and on the upper deck, good and suitable hose to stand
a pressure of not less than 100 lb. per sq. in., long enough to reach
all parts of the vessel and properly provided with nozzles.
Every steamer exceeding 200 tons burden and carrying passen-
gers shall be provided with two good double-acting fire pumps to
be worked by hand, each chamber of such pumps shall be of suffi-
cient capacity to contain not less than 100 cu. in. of water; and
such pumps shall be placed in the most suitable parts of the vessel
for efficient service, having suitable well-fitted hose to each pump,
of at least one-half the vessel in length. On every steamer not
nvJ^v^
FIRE MAIN 611
exceeding 200 tons, one of such pumps may be dispensed with.
Each fire pump thus prescribed shall be supplied with water by a
pipe passing through the side of the vessel so low as to be at all
times under water when she is afloat. Every steamer shall also
be provided with a pump which shall1 be of sufficient strength and
suitably arranged to test the boilers. (Abstracts from U. S. Steam-
boat-Inspection Rules, sec. 4471.)
Fire Main (Water). — This consists of a pipe running fore and
aft practically the entire length of the ship with numerous vertical
branches called risers. At each riser a valve is fitted close to the
main line so that any riser can be shut off if desired. A special
fire pump is connected to the fire main as are also other pumps,
a,s the donkey, which can be started should the fire pump break
down.
The U. S. Steamboat-Inspection Rules (1916) state: "All pipes
used as mains for conducting water from fire pumps on board
vessels in place of hose shall be of wrought iron, brass, or copper
pipe, with brass or composition hose connections.
"Steamers required to be provided with double-acting steam
fire pumps or other equivalents for throwing water shall be equipped
with such pumps according to their tonnage as follows :# Steamers
over 20 tons and not exceeding 150 gross tons shall have not less
than 50 cu. ins. pump cylinder capacity. Steamers of over 150 gross
tons and under 3,000 tons shall have not less than one-third of one
cubic inch pump cylinder capacity for every gross ton. Steamers
of 3,000 gross tons and over shall have pump cylinder, of not less
than 1,000 cu. ins. capacity.
"Upon such steamers fire mains shall be led from the pumps
to all decks, with sufficient number of outlets arranged so that
any part of the steamer can be reached with water with the full
capacity of the pumps and by means of a single 50-foot length of
hose from at least one of the outlets. On all classes of steamers
every such pump shall be fitted with a gauge and a relief valve
adjusted to lift 100 lb.
"All steam fire pumps required shall be supplied with connecting
pipes leading to the hold of the vessel with stopcocks or shut-off
valves attached and so arranged that such pumps may be used
for pumping and discharging water overboard from the hold.
"All fire hose shall be tested to a pressure of 100 lb. to the square
inch at each inspection."
For Pumps, see section on Pumps.
Digitized by LjOOQ IC
612
HEATING
Water Streams
Discharge from Nozzles at Different Pressures
Height
Pressure
Horizontal
Friction
Friction
Nozzle,
of
at Play
Projection
Gallons per per 100 Ft.
per 100 Ft.
Dia. Ins.
Stream
^
of Streams
Minute
of Hose
of Hose —
Ft.
Ft.
Lb.
NetH'dFt.
1
70
46.5
59.5
203
10.75
24.77
1
80
59.
67.
230
13.
31.1
1
00
79.
76.6
267
17.70
40.78
1
100
130.
88.
311
22.50
54.14
IX
70
44.5
61.3
249
15.50
35.71
VA
80
55.5
69.5
281
19.4
44.7
VA
90
72.
78.5
324
25.4
58.52
m
100
103.
89.
376
33.8
77.88
IX
70
43.
66.
306.
22.75
52.42
IX
80
53.5
72.4
343
28.4
65.43
IX
90
68.5
81.
388
35.9
82.71
IX
100
93.
92.
460
57.75
86.98
IK
70
41.5
77.
368
32.5
71.88
IX
80
51.5
74.4
410
40.
92.16
IX
90
65.5
82.6
468
51.4
118.43
m
100
88.
92.
540
72.
165.89
See Flow of Water in Pipes; and Loss of Pressure.
Fire Main (Steam). — The U. S. Steamboat-Inspection Rules
(1916) state: "The main pipes and their branches on steamers car-
rying passengers or freight, to convey steam from the boilers to the
hold and separate compartments of the same shall be not less than
\l/2 ins. in diameter. Steam pipes of not less than % of an inch
in diameter shall be led to all lamp lockers, oil rooms and like
compartments, which lamp lockers, oil rooms and compartments,
in all classes of vessels shall be wholly and tightly lined with metal.
All branch pipes leading into the several compartments of the hold
shall be supplied with valves, the handles distinctly marked to
indicate the compartment or parts of the vessel to which they lead.
"These valves or their handles shall be placed in the most acces-
sible part of the main deck of the vessel and so arranged that all
can be inclosed in a box or casing, the door of which shall be plainly
marked with the words — Steam fire apparatus.
"On all oil-tank steamers the valves instead of being located
near the hatches on the upper deck, shall be all in an accessible
house in which the operator is well protected from heat and smoke;
Provided, That on oil-tank steamers a main line of steam smothering
nvJ^v^
SPRINKLER SYSTEMS 613
pipe of sufficient area to supply all branch pipes leading from the
same to the tanks may be run the entire length of the deck, and
only the main stop valve of the main line shall be required to be
housed. All branch pipes shall be provided with valves which shall
be left open at all times, so that the steam may enter all compart-
ments simultaneously. Such branches as may not be required
after the fire is definitely located may be shut off, in order that
the entire system may be concentrated on one tank.
"Provided, That carbonic acid gas or other extinguishing gases
or vapors may be substituted in place of steam as aforesaid and
for the above described purposes, when such gas or vapor and the
apparatus for producing and distributing the same shall have
been approved by the Board of Supervising Inspectors; Provided,
That the use of such apparatus shall be allowed by law.
"Provided further, That pipes for conveying steam from the
boilers, or pipes for conveying carbonic acid gas or other extin-
guishing vapors for the purpose of extinguishing fire, shall not be
led into the cabins or into passengers' or crew's quarters."
Sulphur Dioxide and Sprinkler Systems. — Of the former is
Grimm's fire extinguishing and fumigating apparatus built by A.
Low & Sons, Glasgow. Here commercial sulphur, or roll brim-
stone as it is known in the trade, is put into a furnace into which
air is forced in such quantities as to form perfect combustion, the
continuance of which is dependent only upon the periodical supply
of sulphur, and this is accomplished by a patented device on top of
the machine through which no sulphur fumes can escape. The
furnace is placed inside a water jacket of rectangular form through
which water is circulated. The gas is forced from the dome of the
furnace by its elasticity, and after passing through cooling tubes
in the water jacket it is then discharged from the machine in a dry,
cool condition, whence it is conveyed through a pipe or hose to its
destination. One of the features of this system is that the air
only is pumped and that into the furnace where the gas is gener-
ated; thus the gas is discharged under pressure, so that it does not
come in contact with the blower.
The following is a description of an installation on the steamer
Minnesotan of the American-Hawaiian Co. The gas machine is
placed in a steel deck house 8 ft. by 13 ft., on the upper deck just
abaft the funnel; from this a 3-in. main discharge pipe extends
on the starboard side forward and aft under the shelter deck. The
main pipe leads to 6 valve chests, all on the shelter deck, from
Digitized by VjiOOQIC
614 HEATING
which 2J^-in. branch pipes extend to 2 ft. from the floor of each
hold. The vertical branch pipes are laid well up against the bulk-
heads or against the ship's frames. All the piping is of galvanized
iron.
Sprinkler Systems. — There are two types, viz., the wet and the
dry pipe. In the former, water is always in the pipes and when
the valves open, due to the rise in temperature caused by a fire, it
rushes out at once. One of the disadvantages of this system is
that if the pipes are not well covered the water will freeze in
winter and burst them.
In the dry pipe system, pressure tanks are provided containing
sufficient water for a primary supply, the water being held in check
by a specially designed valve, which is made inoperative by the
water under pressure on the one side and air under pressure on the
other side. When the heat from the fire melts the solder on the
sprinkler, the head opens, liberates the air in the pipes and reduces
the air pressure, allowing the valve to open and the water to fill the
pipes and flow out of the open head. The fire pumps being con-
nected to the sprinkler system are immediately started and reinforce
the water supply to the sprinklers.
Fire Alarms. — Of the alarms the one sold under the trade name
Aero (Aero Automatic Fire Alarm Co., New York) should be noted.
This consists of a small hollow tube extending around the moldings
in the passageways, staterooms, and holds, the tube leading to a
cabinet that contains a sensitive diaphragm and electric contacts.
The heat from a fire heats the air in the tube, causing expansion
through its entire length, thus moving a diaphragm and closing
an electric circuit that causes bells to ring, and furthermore shows
by an indicator . the room the fire is in. The alarm can be given
in as many places as desired and connected by electric wires to
a central station or fire headquarters that may be located con-
venient to the captain's and chief engineer's rooms.
Digiti
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SECTION IX
SHIP EQUIPMENT
Steering Gear. — The requirements of a steering gear are: (1) to
move the rudder to any position with as little delay as possible;
(2) to hold the rudder in position under the stresses imposed in ma-
neuvering the ship; (3) to give way before any abnormal stress
such as caused by a wave, and automatically to return to its former
position; (4) to be absolutely reliable; and (5) to be economical.
Savings of as much as 6% of the running distance of vessel per
annum can be secured with the most sensitive steering gear. Steam,
hydraulic, and electric power have beenjemployed, steam more than
any other.
Steam steering gears may be divided into two classes, viz., direct
and indirect connected. In the former the engine is direct connected
by gears to the rudder quadrant as in Fig. 104, the steam to the
cylinders being controlled by a valve operated from the pilot house
or bridge, the piston being direct connected to the tiller ropes
and chains. In the indirect, which is more common, the rope or
chain to the tiller or quadrant passes over a drum which is turned
by a pair of steam cylinders having a controlling valve connected
to the steering wheel in the pilot house. See also Arrangement
and Transmission.
Usually eight turns of the steam steering wheel are required to
put the rudder from hard over on one side to hard over on the other,
and 24 turns on the hand wheel are required on some vessels and
16 on others.
For steamers 250 ft. in length Lloyd's rules state "that they
are to be fitted with two independent steering gears, one of which
must be a steam or other mechanical steering gear, and it is recom-
mended that the two controlling wheels of the mechanical gear be
placed one at the gear and the other one on the navigating bridge."
Steam steering gear using the follow-up system of control has
been installed for many years on naval vessels. In this system,
the arrangement of the valve gear is such as automatically to cut
off the steam when the rudder has reached an angle corresponding
to a position determined by the helmsman. In the follow-up con-
trol system as applied to electric steering gears there is a master
OlO Digitized by vjiOOQIC
616 SHIP EQUIPMENT
Steam Steering Engines (Steam Only Type)*
(American Engineering Co.)
Cylinders
Ins.
Length
Width
Height
Weight
Lb.
Vessels Suitable for
3HX3H
4^X4^
5 X5^
6 X6
7 X7
8 X7
10 X8
12 X8
3'1M*
3' 10H"
4' 2^"
4' 7H"
5' 7"
5' 11*
3' AH"
4' OH"
4' 2"
5' OH*
5' 2"
2'5M"
2f9H"
3' 3J4"
V hH"
A'2H"
4'5H"
1,660
1,850
3,160
4,100
4,850
5,650
7,000
8,000
Tugs or yachts
Tugs or yachts
Steamers up to 1,500 tons
Steamers up to 2,500 tons
Steamers over 2,500 tons
Steamers over 2,500 tons
Steamers over 2,500 tons
Steamers over 2,500 tons
♦Engines for combined steam and hand are the same size only they weigh
about 800 lb. more in the large sizes. In both cases the weight of the engine
and steering column is included in the weight given. All the engines have two
steam cylinders. "Steam only" type means that the engines have neither steam
nor hand wheels, being controlled from a distant standard.
controller located in the steering room and connected to the steer-
ing wheel by shafting and ropes, making it possible for the helms-
man to set the steering gear at any desired angle as the motor will
automatically accelerate and move the rudder to the predeter-
mined angle at which the follow-up control will automatically stop
the motor.
In the non-follow-up control with electric steering gears a master
switch or switches are supplied, making it possible for the operator
to start the motor by a small movement of the master switch from
any desired station and shut the motor down as soon as the rudder
has reached the desired angle. With this form of control it is
necessary to have a helm angle-indicating device. The non-follow-
up control is installed on many of the latest vessels of the U. S.
Navy.
Electric steering gears* may be divided into two classes: (1) the
variable voltage and (2) contactor rheostatic. In the former
the equipment consists of a rudder motor, motor generator, switch-
board, steering stands, selective switch and limit switch. The
speed of the motor is controlled by varying the field strength of
the generator. There is no follow-up device. In (2) the equip-
ment required consists of a steering motor, contactor controller
with rheostats, limit switch, and any desired number of master
steering controllers. U. S. battleships so equipped are the Texas
and New York.
* From Naval Electrician's Handbook. W. H. G. Bullard.
Digitized by VjiOOQIC
STEERING ARRANGEMENTS
617
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trnf/ne
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J)o£/£/e f*4/rc6crse
p~
T
-Mr— 41?-
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2)oi/6/e /^t/SC/tcrse ~//ar/9e/Sfe*r/>?p ca/? 6* c/Zscon/tecfec/
Figure 102. — Hand and Steam Steering Arrangements.
Digitized by LiOOQ LC
618
SHIP EQUIPMENT
Installation?
Type of Vessel *
Length Between
Perpendiculars,
Feet
H. P, of
Steering
Engine
Tugs up to
Small screw passenger steamers up to. . .
Steam lighters and tugs
Steam lighters and tugs
Screw passenger steamers
* Rated H. P. as installed by Dake Engine Co.
80
100
80-100
100-140
190-210
5
5
7
10
15
Length*
Speed
Knots
280
18H
310
14
360
13
400
13
425
13
480
14K
552
18
600
22
Diameter
Rudder
Stock, Inches
Size of Steering
Engine
Cylinders (2)
Name of
Steamer
Owner
7H
9
10
11
11
15%
18
6 X8
8 X8
7H X 12
7 X8
9 X 12
7H X 12
7H X 11
12 X 12
Dover
Moana
Queen Olga
Trieste
Tintagel Castle
Southwark
Korea
Lucania
London, Chatham
<fc Dover Ry.
New Zealand Co.
Russian Volun-
teer Fleet
Austrian Lloyds
Castle Line
American Line
Pacific Mail
Cunard
* Steamers in this table have Brown's steam tiller and telemotor installed.
The distinguishing features of the contactor rheostatic control
are: (a) direct application of power to the screw gear by a motor
taking current direct from the ship's power mains; (b) steering by
means of a master lever with steadying grip for the helmsman, the
lever automatically returning to the off position if released when
moved in either direction; (c) the elimination of the follow-up
feature, the rudder starting promptly and continuing to move in
the direction indicated by the master steering lever, until the lever
is returned to the off position. The rudder is stopped almost
instantaneously by a powerful dynamic brake and a magnetic disk
brake on the armature shaft.
Among the advantages claimed for an electric steering gear are
the reduction of the weight and space occupied by the driving
mechanism, and the obtaining of a mechanism more efficient in
its operation than steam.
Digitized by VjiOOQIC
3}*-**
619
zed by G00gk
620 SHIP EQUIPMENT
Arrangements. — The steering engine may be in the pilot house
with the steering wheel standard, or in the engine room with rope
and rods from the standard to the throttle of the engine, or the
engine may be in the compartment directly below, or in the compart-
ment aft with the quadrant. When the relative position of the
steering wheel and engine requires long transmission the steam-only
type of engine with separate hand wheel is installed.
Tugs and harbor craft generally have the quadrant and the
engine so connected that when the wheel in the pilot house is turned
to port the rudder turns to starboard. In steamers, the connections
are such, if the wheel is turned to port the rudder goes to port.
The Brown steam tiller (built by Hyde Windlass Co.), equipped
with hydraulic telemotor transmission for controlling the engine
valves from the pilot house and bridge, has been installed on many
large steamers. It consists of two steam engines mounted on a
movable tiller. The engines by means of a worm and wheel and
friction clutch drive a pinion (which is connected to the clutch)
along a toothed segment. At the other end of the tiller is another
segment with teeth that mesh with a pinion fastened to the rudder
stock. When a heavy sea strikes the rudder the clutch slips,
allowing the rudder to move out of position, but by so doing the
steam valve is opened and the engines bring the rudder back to its
normal position.
One of the oldest direct connected types is the Napier screw.
Here the rudder crosshead is operated by two links connected to
a block actuated by a right and left hand screw. The screw may
be operated from the engine by helical gears or by spur gears or by
worm and wheel. The throttle of the engine is controlled from the
standard in the pilot house.
Another arrangement is to have teeth on the rudder quadrant
which mesh with pinions driven by a steam engine or an electric motor.
A quadrant with springs may be used, the springs absorbing the
shocks between the rudder and the engine. The Hyde Windlass
Co. build their quadrant and gear type of steering engine with a
friction clutch on the gear shaft similar to the one outlined above
for the Brown steam tiller. See Fig. 104a.
In electric steering gears the master controller may be located
in the pilot house, the motor being in the steering compartment aft.
Transmission. — Shafting and gears between the steering engine
and the standard in the pilot house are undesirable owing to the
settling and moving of the decks resulting in throwing the shafting
Digitized by VjOOQ 1C
SHAFT TRANSMISSION
621
Figure 104a. — Plan of Steering Engine with Quadrant. Elevation shown on
page 622. {Hyde Windlass Co., Bath, Me.)
out of line. A satisfactory transmission for long distances con-
sists of a drum forward and another aft connected by a J^-inch wire
rope, provision being made for taking up the slack; by means
of fair leads the rope can be run around obstructions and other
places, which would be impossible with shafting.
When a clear runaway is available a sliding shaft transmission has
been successfully employed. The shaft running fore and aft is sup-
ported on rollers and has a rack fitted at each end. These racks en-
gage with pinions of which the forward one rotated by the wheel in
the pilot house gives endwise motion to the shaft. The motion thus
transmitted rotates the after pinion, thus controlling the opening of
the steam valve by operating through suitable lever connections.
y Google
622
SHIP EQUIPMENT
Figure 104b. — Elevation of Steering Engine Shown in Place on Page 621.
Another flexible transmission is the hydraulic telemotor, where
the transmitting cylinder in the pilot house is connected with
the controlling valve at the steering engine by copper pipe of small
diameter. The whole system is charged with water and refined
glycerine in equal parts, or with a special telemotor oil.
Some builders put a specially designed check valve at the engine
for cutting off the steam when the engine is at rest. /
In electric installations only small wires for conducting the
current are required, thus making a very neat arrangement which
is preferable to long steam lines.
Digiti
zed by G00gk
PRESSURE AND HORSE POWER 623
To Calculate the Power Required to Turn the Rudder of a Vessel.
Let m = moment of pressure of water on rudder relative to its
axis in foot-pounds
A — area of rudder in square feet
V = speed of boat in knots per hour
d = distance of center of gravity of rudder surface from
axis of rudder in feet
C = constant - 2.8523
0 = angle rudder makes with center line of boat
Then m - A X C X V2 X d X (sin 6)
The above formula will give the strain on the rope and the re-
sistance to be overcome by the steering engine.
When the steering engine Is of the usual two-cylinder type with
cranks at right angles the American Bureau of Shipping gives the
formula
2,000
Where p = steam pressure at steering engine in pounds
d = diameter of cylinder in inches
I = stroke of cylinder in inches
n = number of revolutions of steering engine required to
move helm from mid-position to hard over
D = diameter of rudder head in inches
To find the force exerted by the man at the wheel, multiply the
radius of the wheel by about 100 or 125 lb. Rudders in large steam-
ers seldom turn beyond 15° on account of the power required to
turn them.
Pressure and Horse Power. — The pressure on a rudder at right
angles (90°) to the ship's direction is found from the formula,
1.12 X j~ speed of ship in feet per second X area of rudder.
The correction for any angle of rudder is to multiply the pressure
just given by the sine of the angle. This gives the pressure on the
rudder in pounds, and to get it in tons divide by 2,240. Speed is
in feet per second and the area in square feet. The pressure per
square foot of rudder area increases as the square of the speed so
that in comparing 22 and 18 knots the proportion of pressure for
equal areas is ^ = r^r = 1.5, that is, an increase of 50%.
AM • . A , 3.1416^ w torsional strength of rudder stock
Momenttoberesisted jg— X factor 0f ^fety
where d = diameter of rudder stock.
Digitized by LiOOQ 1C
624 SHIP EQUIPMENT
The moment to be resisted determines the net horse power of
the engine, as
1 unit of work = 1 foot-pound
1 horse power = 550 units per second, or 33,000 ft.-lb. per min-
ute.
Then the net horse power required by the steering engine will
, moment to be resisted
be 550
If this equation is followed out it is found that the slower the
rudder has to be turned the less is the power required and vice versa.
To the net horse power must be added the power to overcome
friction of tackle, gear, etc.
Rudders, see Structural Details.
Steering Chain and Rod. — The following formula is given by
the American Bureau of Shipping, d = .4 y -L
Where d = diameter of chain in inches
D = diameter of rudder head in inches
R = radius of quadrant or length of tiller in inches
The diameter of the steering rods are one-quarter larger than
the chain links as determined by the above rule.
Windlasses may be steam or electric driven, but generally steam.
On large sizes the wildcats over which the anchor chain passes
can be operated by power or by hand. The wildcats are inde-
pendent and are set up close against the side bitts, with the com-
pressors (sometimes called friction brake bands) next the bitts.
The engines are usually reversible, which permits the anchor chains
to be drawn from the lockers by power. When letting go an anchor
its weight will take the chain from the locker, the wildcat being
unlocked from the windlass shaft.
As to methods of drive, this may be by spur gears, worm and
wheel, or by messenger chain. Among the advantages claimed by
one builder in a compound spur-geared windlass are 54% greater
chain speed than in the worm gear type, 14% excess pulling power
at high speed, and smaller deck space and height. Messenger chains
consisting of a sprocket wheel on the engine and another on the wind-
lass shaft over which runs a chain are used only when the engine
and windlass cannot be placed close together or as one unit.
Chain stoppers are fitted to relieve the strain on the wildcats
when a vessel is riding at anchor. They should be placed high
enough to cause the chain to rest hard on the bridge under the
ioogle
BRAKE WINDLASSES
625
pawl. As a guide for setting a stopper, draw a line from the bottom
of the hawse pipe to a point 4 ins. above the bottom of the chain
groove in the wildcat. Place wood chocks on this line and bolt
them securely to the deck. Then fasten the chain stopper to the
chocks.
Speed for lifting loaded cable should not exceed 25 ft. per minute.
Speed for lifting slack cable should not exceed 38 ft. per minute.
A windlass is sometimes combined with a capstan; that is, the
windlass is on one deck and on the deck above is the capstan driven
from the windlass shaft by means of bevel gears and a vertical
shaft.
Dimensions of Steam Pump Brake Windlasses
Engines are vertical with two
cylinders, drive windlass shaft by worm and
gear, built by American Engineering Co.
Size of Chain
Ins.
Diameter of
Gypsy Head
Ins.
Deck Space
Ins.
Engine
Ins.
Weight
Lb.
%
5
39 X 52
4X4
1,850
%
6
45 X 62
4X4
2,550
%
6
52 X 74
5X5
4,200
i
8
57 X 72
5X5
5,250
m
9
68 X 84
5X5
6,900
IX
10
70 X 87
5X7
8,400
\%
nx
70 X 89
6X8
9,000
VA
11H
77 X 103
7X8
13,000
m
13
77 X 111
8X8
13,600
i%
15
81 X 113
9X9
17,500
w%
15
81 X 113
9X9
17,600
2
15
100 X 141
10 X 10
32,600
2«
18
100 X 141
10 X 10
33,100
2M
18
110 X 147
12 X 12
39,600
With electric operated windlasses the controller is so designed
as to give several speeds in either direction and if there is a heavy
overload the motor will automatically be slowed down; when the
overload is removed the motor will accelerate to the speed desired
by the operator. Powerful disk brakes are usually supplied with
anchor windlass equipments. On some requiring large horse
power there are two motors with one controller, and the controller
is arranged so that the motors may be operated individually, in
parallel or in series. With the latter connection, torque may be
Digitized by VJiOOQ 1C
626
SHIP EQUIPMENT
obtained on the windlass equivalent to the torque of both motors,
without using more current than is required by one motor.
Winches or hoisting engines are primarily for handling freight,
although when fitted with a gypsy head they are employed for
warping a vessel into a dock or alongside a pier. Steam deck
winches may be either spur-geared or friction-geared; that is, the
drum is driven by the engine by gears or by some kind of frictional
device. The spur-geared has three different methods of operation:
(1) by means of a cone friction drum, (2) by link motion, and (3)
by a positive clutch on the crank shaft.
In the first or cone friction type (as built by the American Engi-
neering Co.), the cones are thrown out of contact and the drum which
is loose on the shaft would be overhauled by the load except for a
powerful adjustable strap brake which controls the drum and is oper-
ated by a foot lever. The drum can also be controlled, while
lowering its load, by the cone friction arrangement. This, how-
ever, causes the cones to wear very rapidly, and necessitates fre-
quent renewals. It is preferable, then, that the cone friction be
used only for hoisting and that the brake be depended upon for
lowering the load.
The second or link motion is for reversing winches when the
load is lowered by reversing the engine, thus keeping the load
at all times under the control of the engine. This type is often
called a winding or an elevator winch. The link motion can also
be used for ordinary hoisting, but the lowering is much slower
than when lowering by gravity.
With the clutch winch, the drum and gear wheel are keyed fast
Cone Friction Deck Winches
Cylinder
Drum
Size of
Bed Plate
Hoisting
Capacity in
Weight
Lb.
Dia.
Stroke
Dia.
Length
Ins.
Lb.
Ins.
Ins.
Ins.
Ins.
5
5
8
16
36 X 32
1,200
1,800
6
6
10
18
48 X38
2,000
2,500
7
7
12
24
50 X47
3,000
3,700
8
8
15
24
66 X 48
4,000
4,200
10
10
18
30
69 X 56
6,000
6,000
Double-cylinder engines, single drum.
American Engineering Co., Philadelphia, Pa.
Digiti
ized by G00gk
FRICTION GEARED WINCHES
627
to the shaft, the former having a flange for a strap brake. The gear
wheel is driven by a pinion clutched to the crank shaft. In hoist-
ing, the load is raised to the desired height and the winch stopped.
The strap brake is then applied to the drum and the clutch on
the crank shaft thrown out of gear with the pinion. This puts the
load, when being lowered, under the control of the strap brake.
Friction geared winches are designed for fast hoisting and quick
operation. They are adapted for general cargo and wharf pur-
poses and are faster than spur-geared winches. The weight hoisted
is thus less for a given size of engine but the speed is correspond-
ingly greater.
Friction Gear
ed Hoisting Winches
Cylinder
Drum
Size of
Bed Plate
Hoisting
Capacity in
Weight of
Winch
Dia.
Stroke
Dia.
Length
Ins.
Lb.
Lb.
Ins.
Ins.
Ins.
Ins.
4
4
5
12
34 X28
700
1,000
5
5
8
16
36 X 30
1,000
1,800
6
6
10
18
47 X38
1,800
2,500
7
7
12
18
60 X 42
2,000
3,000
7
8
15
18
66 X 42
2,500
3,500
8
8
18
18
66 X 39
3,000
4,200
8
10
24
24
54 X 50
3,000
5,000
10
10
24
30
69 X 60
3,500
6,500
The winches have double cylinders, single drum.
American Engineering Co., Philadelphia, Pa.
Friction Winches
Weight
Hoisted
Single »
Line
Lb.
Speed
Feet per
Minute
Size of Hoist Drums
Horse
Power
Diameter
Ins.
Length of
Body
Between
Flanges
Weight
Lb.
5
7
10
15
20
30
670
1,045
1,510
2,290
3,300
5,591
185
166
164
162
150
133
6
8
9
10
12
14
15
17
22
21
20
800
1,200
1,950
2,600
3,300
4,000
The above winches have two drums each of the size given. The winches could
be double-geared, thus increasing the lifting capacity twice and decreasing the
lifting speed to one-half the ratings given. (Dake Engine Co., Grand Haven,
Mich.)
Digitized by VJiOOQLC
628
SHIP EQUIPMENT
In electric driven winches the controller is placed near the winch
or is attached to it. As the motor is commonly direct connected
to the winch, it gives extremely smooth running. The controller
may be of the full reverse type, in which case the motor is reversed
by moving the handle of the controller to either side of the off
position, or reversing may be obtained by means of an auxiliary
reversing switch mounted in the same drum with the main operating
cylinder of the controller.
Electric Winches
Drums
Horse
Power
Hoisting
Speed
Feet per
Min.
Hoisting
Capacity
on One Line
Lb.
Diameter
Ins.
Length
Ins.
Shipping
Weight
12
12
14
14
14
16
22
22
26
26
27
32
10
15
20
25
35
50
150
150
150
150
150
150
2,000
3,000
4,000
5,000
6,500
9,000
4,200
4,800
5,800
7,000
8,500
12,000
The above have two drums. (American Engineering Co., Philadelphia, Pa.)
Horse Power Required to Raise a Load at a Given Speed.
__ Gross weight in lb. . . , . r . . ,
H. p. = saobo * speed in feet per minute.
To this add 25 to 40% for friction, contingencies, etc.
Rope Capacity of a Drum in Feet
T
r
<o
Figure 106.
Digiti
zed by G00gk
WARPING WINCH
629
Dimensions A, B and C, to be in inches
Rule:
Add the depth of flange A to diameter of drum B.
Multiply the sum by the depth of the flange A.
Multiply the result by the width C of the drum between the
flanges.
Multiply product by figure in column opposite rope size.
Example. (A + B) X A X C X Multiplier.
Multipliers
A-
A-
Vs.
X-
1M-
4.16
Ins.
1.86
IV?,
1.37
IVh
1.05
m
.828
m
.672
2
.465
2%
.342
2%
.262
2%
.207
2V2
.167
.138
.116
.099
.085
.074
.066
.058
.052
.046
.042
Increasing the diameter of the drum will give an increased speed
of hoisting with constant revolutions of the engine or motor, but
the size of the load hoisted will be decreased in the same ratio.
Warping Winch. — Here there are no drums but only gypsy heads
which are for hoisting and hauling where it is not required to coil
the hoisting rope on the drum.
Steam Capstans
Diameter
Height
of
Capstan
Ins.
Double
Cylinders
Diameter
and
Stroke
Ins.
Engine
Deck
Space
Ins.
Circum-
ference
of Rope
Ins.
Of Barrel
Over
Whelps
Ins.
Base
Ins.
Weight
in Lb.
8
ioy2
15*
21
24}i
27H
29H
31J*
33
42
27^
31H
33^
37
37
43
40
4X4
4 X6
4 X6
5 X7
6 X8
7X8
8X8
27 X32
38 X42
38 X42
44 X51
50 X60
53 X61
57 X66
4
5
6
1lA
11
900
1,750
1,950
2,900
3,850
5,500
5,800
Capstans on deck, engines below deck. (American Engineering Co., Philadel-
phia, Pa.)
Digitized by LiOOQ LC
630
SHIP EQUIPMENT
Capstans and Gypsy Capstans are either steam or electric driven
and are for warping a vessel alongside a dock. If a capstan is
power driven, means are provided for disconnecting the motive
power so that by inserting bars in the capstan head it can be turned
by hand. When no provision is made for hand operating and no
wildcat is fitted, it is called a gypsy capstan and may be operated
by steam or electricity. Many tugboats have gypsy capstans
for the quick handling of their towlines.
Horse Power
Purchase on Line
Fast Speed
Lb.
Purchase on Line
Slow Speed
Lb.
Shipping
Weight
Lb.
5
7
10
15
20
5,890
6,790
11,000
12,300
19,400
17,670
20,380
33,000
37,120
58,230
1,100
1,550
2,370
2,600
2,950
Fast speed 10 h. p., 15 ft. per min. ; slow, 5. (Dake Eng. Co., Grand Haven, Mich.)
In electric drives there may be a main contactor panel providing
for automatic acceleration and stalling of the motor on heavy
overloads. If desired, controllers may be furnished similar to
those for electric winches.
Electric Capstans
Height
Diameter
From
of
Bottom
Width
Length
Speed
Capstan
Worm or
of Bed
of
of
Motors
Pull
in
Barrel
Bevel
Plate to
Bed
Bed
Horse
in
Feet
Over
Gear
Top of
Plate
Plate
Power
Lb.
per
Whelps
Capstan
Ins.
Ins.
Min.
Ins.
Head
Ins.
10
Bevel
70
47Ji
97
30 |
5,300
13,300
150
60
10
Bevel
52M
47^
73
22 I
3,900
8,500
75
30
13
Worm
61
40
74
30 J
5,940
15,440
90
34
13
Worm
61
55
32^
22 1
3,000
7,710
92
35
13
Worm
61
55
101 J^
30 J
3,762
9,405
100
40
Capstan and motor on deck. (American Engineering Co., Philadelphia, Pa)
Digitized by VJiOOQ 1C
TOWING MACHINES
631
Towing Machines. — In towing,, either Manila or steel hawsers
are used. The former are frequently 12 or more inches in circum-
ference, are elastic and will stretch considerably before breaking,
but they are heavy, bulky, and difficult to handle, particularly
when frozen. Furthermore it is often not practicable to stow a
Manila hawser on a drum, because of its bulk, hence it is coiled or
stretched on deck when not in use.
A steel hawser is stronger than one of Manila of equal weight
and can be stowed by winding it on a drum. However, it has little
elasticity and will break under sudden and severe stresses. Thus
steel hawsers should not be fastened to two rigid connections as
from a bitt on a tug boat to a bitt on a barge, but instead on the
tug should be a steam towing machine which supplies the elasticity
the wire hawser lacks and permits the rapid shortening or length-
ening of the towline when the tug and barge are under way.
Towing machines are steam operated, usually by two cylinders
with cranks at right angles. The steam is admitted to the cylin-
ders through an automatic valve that opens wide as the towline
pays out under the stresses on it, and begins to close when the en-
gine winds it in, stopping the engine when the towline has reached
a predetermined length.
In the machines built by the American Engineering Co., the dis-
tinctive features are the combination of the elastic steam cushion
Towing Machines
(American Engineering Co.)
Diameter
of Rope
Ins.
Diameter and
Length of Drum
Ins.
Deck Space of
Bed Plate
Ins.
Size of Each
Engine
Ins.
Weight
in
Pounds
H
l
IH
IX
IK
2
2K
17 dia. X 18 long
19 dia. X 20 long
21 dia. X 24 long
25 dia. X 28 long
28 dia. X 32 long
34 dia. X 40 long
45 X 63
71 X 71
64 X 65
70 X 73
82 X 82
83 X90
7X7
8X8
10 X 10
12 X 12
14 X 14
16 X 16
18 X 18
20 X 20
4,400
7,300
12,800
17,800
24,700
37,800
48,000
2M
62,000
The above machines include the winding attachment which for the small sizes
averages about 200 lb. and for the large 700 lb. All the machines have two steam
cylinders.
Digitized by VjiOOQIC
632 SHIP EQUIPMENT
and the automatic relief to the. hawser, without which the latter
would be continually straining and frequently breaking. There
is also installed an automatic guiding device that winds the hawser
on the drum in even layers.
ROPE
The following are trade terms:
Yarn, fibers twisted together.
Strand, two or more large yarns twisted together.
Rope, several strands twisted together.
Hawser, a rope of three strands.
Shroud laid, a rope of four strands.
Cable, three hawsers twisted together.
Lay, this means the direction or twist of the wires and strands
composing a rope. A rope is right or left lay according to the di-
rection in which the strands are laid. The regular lay of a wire
rope is to have the wires in each strand twist in the opposite direc-
tion from the strands themselves. The term "Lang's lay" is given
to a rope in which the wires of each strand and the strands them-
selves all twist in the same direction. The chief advantage of
this lay is in the increased distribution of the surface wear due to
the longitudinal direction of the wires.
The principal wear comes from badly set sheaves and excessive
loads. If the rope wears on the outside and is good on the inside
it shows that it has been injured in running over the pulley blocks
or rubbing against some obstruction. If the blocks are very small
the wear of the rope internally will be increased. The size of the
rope selected should be larger than is needed to bear the strain
from the load. Thus a rope twice as strong as needed for strength
alone could be used until one-half its strength was worn away
before it would be required to be renewed.
Speeds. — Slow, derrick and crane, 50 to 100 ft. per minute.
Medium, wharf and cargo, 150 to 300 ft.
Rapid, 400 to 600 ft.
Under ordinary conditions of hoisting coal from a vessel a rope
hoists from 5,000 to 8,000 tons, and under favorable circumstances
up to 12,000. Coal is usually hoisted with what is called a "double
whip," that is, with a running block that is attached to the tub,
which reduces the stress on the rope to one-half the weight of the load
hoisted plus the friction losses. Hoisting ropes are not spliced,
Digitized by VjOOQ 1C
KNOTS AND HITCHES
633
as it is difficult to make a splice that will not pull out while run-
ning over sheaves. The following table gives the usual sizes of
hoisting rope and the proper working load.
Diameter of Rope in
Ins.
Economical Working Load
on the Rope in Lb.
Nominal Size of Coal
Tubs, Double Whip, Tons
m
500
600
750
900
1,250
VitO H
3^ to M
Mtol
1 to VA
Knots and Hitches.* — See Fig. 106. The principle of a knot is
that no two parts that would move in the same direction if the
rope were to slip should he alongside and touching each other.
This principle is shown in the square knot I. A great number of
knots have been devised, of which a few of the most useful are
illustrated on page 635. In the cuts they are shown open, or
before being drawn taut, in order to show the position of the parts.
The names usually given to them are:
A. Bight of a rope P.
B. Simple or overhand knot Q.
C. Figure 8 knot R.
D. Double knot S.
E. Boat knot T.
F. Bowline, first step U.
G. Bowline, second step V.
H. Bowline completed W.
I. Square or reef knot X.
J. Sheet bend or weaver's knot Y.
K. Sheet bend with a toggle Z.
L. Carrick bend AA.
M. Stevedore knot completed BB.
O. Slipknot CC.
Flemish loop
Chain knot with toggle
Half-hitch
Timber hitch
Clove hitch
Rolling hitch
Timber hitch and half-hitch
Blackwall hitch
Fisherman's bend
Round turn and half-hitch
Wall knot commenced
Wall knot completed
Wall knot crown commenced
Wall knot crown completed
The bowline (H) is one of the most useful knots, as it will not
slip and after being strained is easily untied. To tie it, begin
by making a bight in the rope, then put the end through the bight
and under the standing part as shown, then pass the end again
through the bight, and haul tight.
Knots H, K, and M are easily untied after being under strain.
The knot M is useful when the rope passes through an eye and is
* From C. W. Hunt 6 Co., New York.
Digitized by LiOOQ IC
634 SHIP EQUIPMENT
held by the knot, as it will not slip, and is easily untied after
being strained.
A wall knot is made thus: Form a bight with strand 1 and pass
strand 2 around the end of it, and strand 3 around the end of 2,
and then through the bight of 1, as shown in Fig. Z. Haul the
ends taut, as shown in AA. The end of the strand 1 is now laid
over the center of the knot, strand 2 laid over 1, and 3 over 2,
when the end of 3 is passed through the bight of 1 as in BB. Haul
all the strands taut as in CC.
In the stevedore knot (M), N is used to hold the end of a rope
from passing through a hole. When the rope is strained the knot
draws up tight, but it can easily be untied when the strain is re-
moved.
To Find the Tension in a Hoisting Rope, the Acceleration (or
Hoisting Speed) Being Uniform.
Here W = weight to be hf ted in pounds
s = speed in feet per second
g = acceleration due to gravity =* 32.2 ft.
t — times in seconds
Then the tension in the rope is -— ^ \- W
Example. A weight of 4,000 lb. is to be raised 100 ft. in 5 see. Find the tension
■ in the hoisting rope, the hoisting speed being constant.
_ . 2 X IT X S , w 2 X 4,000 X 100 , . ^
Tendon = - - - + W = g- - - + 4,000
= 994 + 4,000 = 4,994 pounds •
Kinds of Rope. — Ropes for marine purposes are made of Manila,
hemp, wire, and wire and hemp. Manila is obtained from the leaf
stalks of the musa iextUis or textile banana, found in the Philippine
Islands. The fiber is strong and durable but not very flexible,
and therefore is not so well adapted to the manufacture of small
cordage as it is for mooring lines, towing hawsers, etc.
Hemp is from the fiber of a plant of the same name. The fiber
is more flexible than Manila but is not so strong nor as durable.
It decays quite rapidly when wet, and hence for marine purposes
is tarred.
Wire ropes usually have a hemp center, the hemp forming a cushion
around which are the strands. Rope with a wire center is about 10%
heavier. The differences in construction are mainly dependent upon
the number of strands, the number of wires in each strand, and their
shape and arrangement.
Digiti
zed by G00gk
KNOTS, HITCHES, BENDS
635
Knots, Hitches, Bends
Be D
Figure 106.
Digiti
zed by G00gk
636 SHIP EQUIPMENT
Approximate Weight and Strength op Pure Manila *
Size in
Siiein
Weight
Strain Borne
Length of
Circumference
Diameter
of 1,000 ft.
by New
Manila Rope in
Inches
Inches
in Lb.
Manila Rope
one pound
h
K
18.34
620
55 ft.
1
A
24.17
1,000
41ft.
1^
i^
36.67
1,275
27 ft.
1M
A
54.17
1,875
18 ft. 6 in.
VA
M
75.
2,400
13 ft. 4 in.
Wi
A
104.17
3,300
9 ft. 7 in.
2
5i
133.34
4,000
7 ft. 6 in.
2M
M
165.
4,700
6 ft. 1 in.
VA
H
195.
5,600
5 ft. 1 in.
2M
%
225.
6,500
4 ft. 5 in.
3
l
270.
7,500
3 ft. 8 in.
3H
1A
315.
8,900
3 ft. 2 in.
VA
1H
360.
10,500
2 ft. 9 in.
3%
VA
420.
12,500
2 ft. 5 in.
4
1A
480.
14,000
2 ft. 2 in.
4M
1M
540.
15,400
1 ft. 10 in.
*lA
1^
600.
17,000
1 ft. 8 in.
m
i*
675.
18,400
1 ft. 6 in.
5
750.
20,000
1ft. 4 in.
5H
«i
900.
25,000
1ft. 1 in.
6
2
1080.
30,000
11 in.
VA
2^
1260.
33,000
. 9H in.
7
2^
1470.
37,000
8 in.
7>3
2^
1680.
43,000
7 in.
S
2^
1920.
50,000
6Jiin.
&M
2J*
2158.34
56,000
5*A in.
9
3
2429.17
62,000
5 in.
9Ji
3H
2700.
68,000
4^ in.
10
3M
3000.
75,000
4 in.
* Moon & Co. — Plymouth rope.
Hemp-clad wire rope consists of wire rope with the strands
served or covered with tarred hemp marline, which prevents fric-
tion between the strands when the rope is in use and affords a
protection against moisture. For marine use this rope has many
advantages over Manila, as it is 3 to 5 times as strong when of equal
size; thus for ropes of equal strength the hemp-clad is about 3/s the
size of a Manila rope, is 50% lighter than Manila rope of equal
strength, and can be readily handled and coiled. Following is a
table of sizes.
Digiti
zed by G00gk
MARLINE
637
Hemp-Clad Wire Cable Laid Hawser*
Composed of Five Ropes, with Hemp Centers, Five Strands to the
Rope, Seven Wires to the Strand
Diameter of
Each Rope
in Inches
before Serving
Approximate
Outside
Diameter of
Hawser after
Serving with
Marline
Approximate
Outside
Circumference
after Serving
Approximate
Breaking
Strain
in Pounds
Approximate
Weight
per Foot
in Pounds
Crucible Cast Steel
X
2%
8K
103,000
3.80
9
2A
: 7*A
80,000
3.20
2
6J4
60,000
2.59
%
V/s
6
50,000
1 2.30
Itt
5%
38,000
2.12
Mild Plough Steel
X
2%
SH
115,000
3.80
§
2*
7H
92,000
3.20
2
VA
67,000
2.59
A
V/s
6
56,000
2.30
Vs
Hi
5%
42,000
2.12
Plough Steel
X
2H
W*
128,000
3.80
ft
2A
7H
105,000
3.20
2
6^
76,000
2.59
A
VA
6
64,000
2.30
Vs
ltt
&A
48,000
2.12
* Crescent rope, Q. C. Moon & Co., New York.
Marline (tarred hemp) is for serving ropes and splices, cotton
line for halliards of sailing yachts when a very soft rope is required,
serving twine for whipping the ends of ropes.
In a flattened strand wire rope the construction is such that
the outer wires conform to a circle, and instead of only one wire
in each strand being exposed to contact there are from 2 to 6,
depending upon the style of construction. This distribution of
Digitized by VJiOOQ
638
SHIP EQUIPMENT
wear minimizes the tendency to brittleness and lighter wire can
be used, which results in extreme flexibility.
Flattened Strand Hoisting Rope*
6 Strands of 25 Wires Each
Approximate
Breaking
Usual
Advised
Diameter
Working
Approximate
Weight per
Diameter of
in
Strength in
Load in
Drum or
Inches
Tons
Tons
Foot
Sheave in
of 2,000 lb.
of 2,000 lb.
Feet
Vs
7.4
1.5
.25
2
X
13.3
2.7
.45
2 75
%
16
3.2
.58
3
21
4.2
.72
3.50
%A
29
5.8
1.00
4
J6
39
7.8
1.38
4.50
l
50
10.0
1.80
5
1H
62
12.4
2.30
6
1M
76
15.2
2.80
7
iVs
92
18.4
3.45
7.50
\XA
108
21.6
4.00
8
Wi
121
24.2
4.75
8.50
IX
146
29.2
5.60
9
2
183
36.6
7.25
11
231
46.2
9.20
12
289
58
11.2
14
W%
317
63.5
12.5
15
2M
345
69
13.8
16
♦Trade name, "Hercules," A. Leschen & Sons, St. Louis, Mo.
Round strand wire rope is composed of a number of wires twisted
into a round strand, which are laid around a hemp or wire center.
These strands usually consist of 6 or 8, which are in turn com-
posed of 7, 9, 12, 19 or 37 wires, although other combinations may
be selected. Rope of 6 strands with 19 wires in each strand is
the number generally selected for the round strand (see table of
Cast Steel Wire Rope). For shipfe rigging, 7 strands and 12 wires.
Experience has shown that wear increases with speed, therefore
true economy results from increasing the load within the safety
limit and diminishing the speed.
For a working factor one-fifth of the ultimate strength of the
rope is usually considered safe, although frequently a greater
factor is required.
Digitized by VjiOOQIC
WIRE ROPE
639
Flattened Strand Cast Steel Rope*
Hoisting
6 Strands of 25 Wires Each
Approximate
Breaking
Usual
Advised
Diameter
Working
Approximate
Weight per
Foot
Diameter of
in
Strength in
Load in
Drum or
Inches
Tons
Tons
Sheave in
of 2,000 lb.
of 2,000 lb.
Feet
X
5.3
1.06
.25
1
H
9.3
1.86
.45
1.50
A
11
2.2
.58
1.75
%
13.8
2.76
.72
2.25
%
19.3
3.86
1.00
3
%
25
5.0
1.38
3.50
l
33
6.6
1.80
4
lVs
42
8.4
2.30
4.50
in ■
52
10.4
2.80
5.
m
62
12.4
3.45
5.50
VA
70
14.0
4.00
5.75
i%
79
15.8
4.75
6.25
i%
94
18.8
5.60
7.25
2
117
23.4
7.25
8
2X
146
29.2
9.20
8.50
2V2
187
37
11.2
10
2%
210
42
12.5
11
2H
232
46
13.8
12
* A cheaper grade than Hercules.
Wire rope must not be coiled or uncoiled like hemp rope. When
not on a reel, roll on the ground like a wheel or hoop to prevent
kinking.
Cast steel wire rope is standard for ordinary work, being of
moderately high tensile strength and quite flexible. It works
to good advantage over small sheaves or drums, but the greater
the diameter of the sheaves and drums the longer the rope will
last. The grooves should be slightly larger than the rope so that
the rope will not bind.
Plough steel wire rope gets its name from a quality of steel
originally used in ploughing, requiring a rope that could be dragged
over stones and rough ground without abrasion. The tensile
strength is high and this rope gives good service where heavy
work is done and where large drums and sheaves are practicable.
Iron rope is much more pliable, is softer, and of a lower tensile
Digitized by VjOOQ 1C
640 SHIP EQUIPMENT
Approximate Comparison op Strength*
Manila Rope
Crescent
. Hemp-Clad Wire
Diameter
Rope —
Extra
Circum-
Diam-
Approximate
Breaking Strain
Iron
Crucible
Strong
Plough
ference
eter
Steel
Crucible
Steel
Steel
w
ft
2,250
X
2
K
3,000
...
» . .
2M
X
4,000
K
"x
• • •
2K
J*
5,000
"x
...
2%
K
5,800
'ft
K
3
l
7,000
. . .
'ft
3K
IK
8,000
K
"ft-
3H
9,200
'k
z%
1M
11,000
. . .
"k
...
4
ift
IK
12,000
K
v%
4M
13,500
. . .
'ft
4K
IK
15,500
. . .
'ft
*X
ift
IK
17,000
X
'k
'ft
5
19,000
• . .
ft
'k
5K
IK
23,500
K
ft
'k
6
2
27,000
K
6K
2K
31,500
i"
K
'k
7
2K
37,000
IK
"x
7K
2K
42,000
"x
8
2K
48,000
i'x
"y»
'ji
8K
2K
54,000
'k
9
3
61,000
IK
i"
'ji
9K
3K
67,000
IK
i"
10
3K
75,000
IK
i"
* G. C. Moon & Co., New York.
strength than steel. It is used principally on elevators and some-
times in the transmission of power.
Tiller rope is made of a large number of small, fine bronze wires
and is the most pliable wire rope manufactured.
For protection against the action of salt air and the weather,
the wires in the ropes are frequently galvanized, as for guys, hawsers,
and ships' rigging.
How to Measure Wire Rope. — It is always understood that the
diameter of a wire rope is that of a circle inclosing the rope. Care
should be taken, in measuring, to obtain this diameter. See Fig. 107.
JvJ^Vl^
WIRE ROPE
641
Figure 107. — Method of Measuring Wire Rope.
Cast Steel Wire Rope
Six strands, 19 wires each, around a hemp center hoisting rope,
round strand
Diameter
Ins.
Circum-
ference
Approxi-
mate
Weight
per Foot
Approximate
Strength
in Tons
Proper
Working
Load in
Advised
Diameter of
Drum or
Ins.
of
Tons of
Sheave
2,000 lb.
2,000 lb.
in Feet
N
N
.10
2.2
.44
1.
%
l
.15
3.1
.62
1.25
IN
.22
4.8
.96
1.50
ft
IN
.30
6.5
1.30
1.75
IN
.39
8.4
1.68
2.
ft
IN
.50
10.
2.
2.25
2
.62
12.5
2.5
2.5
N
2Ji
2Ji
.89
17.5
3.5
3.
N
1.20
23.
4.6
3.5
1
3
1.58
30.
6.
4.
m
VA
2.
38.
7.6
4.5
IX
4
2.45
47.
9.4
5.
IN
4N
4Ji
3.
56.
11.2
5.5
IN
3.55
64.
12.8
6.
IN
5
4.15
72.
14.4
6.5
IN
5N
4.85
85.
17.
7.
IN
*N
5.55
96.
19.
8.
2
6M
6.30
106
21.2
8.
2X
7^
8.
133.
26.6
9.
2M
2X
7N
9.85
170.
34.
10.
m
11.95
211.
42.2
11.
by Google
642
SHIP EQUIPMENT
Galvanized Steel Mooring Lines*
Composed of 6 Strands and a Hemp Center, each Strand composed
of 24 Wires around a Hemp Core
Diameter
Approximate
Approximate
Weight
Approximate
in
Circumference
Strength in Tons
Inches
in Inches
per Foot
of 2,000 lb.
2A
6K
5.81
113
2
6K
5.51
106
1H
6
5.09
98
!»
5K
4.48
88
5K
4.24
82
ltt
5K
3.86
76
IK
5
3.63
74
IK
4K
3.10
63
1A
4K
2.92
55
IK
4K
2.62
50
IK
4
2.15
42
1A
m
1.93
38
IK
3K
1.75
34
1A
3K
1.54
27
l
3
1.38
25
K
2K
1.05
20
ii
2K
.90
17
K
2K
.78
14
* J. Roebling & Sons, New York.
Formulae for Size and Weight of Rope.*
Let c =* circumference in inches
d — diameter in inches
Weight in pounds per fathom of flexible wire rope = .8 X c1
c2
Weight in pounds per fathom of hemp rope = —
o
Weight in cwt. per 100 fathoms of chain cable = d? X 50
dP
Approximate strength of a hemp hawser in tons = —
(1) To find the safe working load for a rope (hemp or Manila),
square the circumference in inches and divide by 7 for the load
in tons.
(2) To find the size of rope for a given load. Multiply the load
* Modern Seamanship. A. M. Knight.
Digitized by LiOOQ 1C
YACHT-RIGGING
643
Galvanized Cast Steel Yacht-Rigging and Guy Ropes *
Composed of 6 Strands and a Hemp Center, either 7 or 19 Wires
to the Strand
Diameter
Approximate
Approximate
Weight
Approximate
Circumference of
in
Circumference
Strength in Tons
Equal Strength
Inches
in. Inches
per Foot
of 2,000 lb.
Manila Rope
IK
4
2.45,
42
13
1A
w
2.21
38
12
IN
3N
2
34
11
1A
3M
1.77
31
10
l
3
1.58
28
9
N
2N
1.20
22
SH
H
2M
1.03
19
8
U
2N
.89
16.8
7
N
2
.62
11.7
6
A
1«
.50
9
5Ji
n
IN
.39
7
±%
**
IN
.34
6
4M
A
IX
.30
5
4J4
N
IN
.22
4.2
Wz
A
1
.15
3.2
3
* J. Roebling & Sons, New York.
in tons by 7 and take the square root of the product for the cir-
cumference of the rope in inches.
(3) To find the size of rope when reeved as tackle to lif t a weight.
Add to the weight one-tenth of its value for every sheave to be
used in hoisting. This gives the total resistance, including friction.
Divide this by the number of parts at the movable block for the
maximum tension on the fall. Reeve the fall of a size to stand
this tension as a safe working load.
(4) To find the weight which a given purchase will lift with
safety. Find the safe working load for the rope to be used (Rule
1). Multiply this by the number of parts at the movable block,
thus giving the total resistance including friction. Multiply the
total resistance by 10 and divide by 10 plus the number of sheaves
used. The result is the weight that may be lifted.
(5) For the safe working load of wire rope take one-sixth of the
breaking strain as given by the manufacturer.
Examples. Find the size of fall needed to lift 10 tons with a three-fold pur-
chase, the fall of which coming from the upper blook is taken through an extra
sheave on the deck for a fair lead.
Digitized by LiOOQ 1C
644
SHIP EQUIPMENT
Galvanized Steel Hawsers *
Composed of 6 Strands and a Hemp Center, 37 Wires to the Strand
Diameter
Approximate
Approximate
Weight
Approximate
in
Circumference
Strength in Tons
Inches
in Inches
per Foot
of 2,000 lb.
2N
7N
8.82
188
2&
7M
8.36
182
2H
7N
8
171
2Ys
6%
7.06
155
2A
6J-S
6.65
140
2
6N
6.30
132
1M
6
5.84
125
m
5X
5.13
112
IX.
5N
4.85
104
m
5N
4.42
97
in
5
4.15
87
1H
iU
3.55
76
1A
VA
3.24
72
IN
4M
3
66
IN
4
2.45
54
1A
3N
2.21
47
IN
3H
2
42
1A
3N
1.77
38
l
3
1.58
31.5
N
2Ji
1.20
26
i*
2H
1.03
22
N
2N
.89
20
* J. Roebling & Sons, New York.
Total resistance including friction — 10 +
17
Maximum tension onfall = -r — 2.8 tons
o
7 X 10
10
17 tons
Size of fall (Rule 2) - V 7 X 2.8 = 4.4 inches
What weight can be lifted by a fall of 4}£-inch Manila rope reeved as a three-
fold purchase, the fall of which leads from the upper block through an extra leader
on the deck.
4 5a
(Rule 1) Safe working load — — '■=- = 2.9 tons
Total resistance including friction — 6 X 2.9 = 17.4 tons
(Rule 4) Weight to be lifted
17 4 X 10 174
10+7
- -pr - 10.2 tons
Digitized
by Google
GUY HOPES
645
Galvanized Ships' Rigging and Gut Ropes*
Composed of 6 Strands and a Hemp Center, 7 or 12 Wires to the
Strand
Diameter
Approximate
Approximate
Weight
per Foot
Approximate
Circumference of
in
Circumference
Strength in Tons
of 2,000 lb.
Equal Strength
Inches
in Inches
Manila Rope
IX
5X
4.85
42
11
Hi
5X
4.42
38
10X.
IX
5
4.15
35
10
IX
4X
3.55
30
9X
1A
4X
3.24
28
9
IX
4X
3
26
8X
IX
4
2.45
23
8
1A
3X
2.21
19
7X
IX
3X
2
18
6X
1A
3X
1.77
16.1
6
1
3
1.58
14.1
5X
X
2X
1.20
11.1
5X
H
2X
1.03
9.4
5
X
2X
.89
7.8
4X
X
2
.62
5.7
4X
ft
IX
.50
4.46
3X
IX
.39
3.39
3
A
IX
.30
2.35
2X
X
IX
.22
1.95
2X
•'A
1
.15
1.42 ,
2
A
X
.125
1.20
IX
X
X
.09
.99
IX
A
X
.063
.79
IX
A
X
.04
.61
IX
* J. Roebling & Sons, New York.
BLOCKS
The swallow of a block is the space through which the rope
passes. The side pieces of the frame are the cheeks, and the end
of the block opposite the swallow the breech.
The size of a block is measured by the length of the shell and
the length of the shell is determined by the size of rope to be reeved
through it. For ordinary purposes three times the size of the
rope to be reeved gives the size of the block. Where it is impor-
tant to minimize friction, as in boat falls, 3 J^ X the size of the rope
gives the size of block.
22
646
SHIP EQUIPMENT
Galvanized Steel Hawsebs*
Composed of 6 Strands and a Hemp Center, each Strand consisting
of 12 Wires and a Hemp Core
Diameter
Approximate
Approximate
Weight
per Foot
Approximate
Sise of Manila
in
Circumference
Strength in Tons
Hawsers of
Inches
in Inches
of 2,000 lb.
Equal Strength
2A
M
4.43
83
2
■ 6M
4.20
77
ltt
6
3.89
71
18
5%
3.42
66
•
5N
3.23
61
13.5
m
IN
5Ji
2.94
57
13
5
2.76
53
12.5
IN
w
2.36
45
12
1A
4H
2.16
41
11.5
IN
4M
2
38
11
IN
4
1.63
31
10
1A
3H
1.47
28 '
9.25
IN
m
1.33
26
8.75
* J. Roebling & Sons, New York.
Length of Rope Required for Splices
Circumference
Allowance for
Allowance for
of Rope
Iron Wire Rope
Steel Wire Rope
Manila
Inches
Inches
Inches
•
1
9
.12
An average
Hi
12
18
[ allowance of
2
15
21
15 inches
2y2
18
24
3
20
30
3^
22
33
4
24
36
18 inches
4J4
27
39
j or over
5
30
42
6
35
48
7
40
54
Snatch blocks are single metal or iron-bound wooden blocks,
with the shell cut away immediately over the swallow so that
a rope can be lifted in and out of the block without reeving its
end through first. The iron strap over the swallow has a hinged
flap which is clamped and pinned when not in use.
y Google
TYPES OF BLOCKS
647
Swivel blocks are metal or iron-bound blocks supported by a
swivel so they can turn in any direction.
Gin blocks have metal pulleys in metal frames.
Cat and fish blocks are heavy double or treble blocks with large
open hooks for catting and fishing for an anchor.
Blocks with different connections are shown in Fig. 108.
Figure 108.— Types of Blocks. (Boston A Lockport Co., Boston.)
A Solid eye
B Loose hook
C Loose front hook
D Jib sheet blocks to side
E Jib sheet blocks fore and aft
F Span and bridle block attachment
G Side sister hook double block
H Side sister hook single block
I Regular shackle
J Fiddle block
K Ring, front or side
L Loose swivel hook
M Regular shackle
N Upset shackle
O Stiff swivel hook
P Loose side hook
Q Reverse shackle
R Reverse upset shackle
S Deck leader, bolt and nut
T Stiff front hook
U Coleman hook
V Deck leader
Digitized by VjiOOQIC
648
SHIP EQUIPMENT
Wood Blocks for Manila Ropb
Type of Block
Nomi-
nal
Sue
Width
of
Shell
Inches
Sue of
Weight
of Block
Si mile with hook
Double with hook
Single with hook
Double with hook
Triple with hook
Single* with hook
Double wi Lfa hook
Triple with hoolc
Quadruple with Bhackle
Single with hook
Double with hook
Triple wiiii hook
i.'iki-jrupli. with shackle
Single with fa oak
Double with hook
Triple with hook ,
Quadruple with hook...
Soateh block
Snatch block
8
8
12
12
12
14
14
14
14
16
16
16
16
20
20
20
20
16
20
15
20
45
70
95
70
115
150
190
90
140
190
270
170
230
360
430
50
95
American Bridge Co., New York.
Steel Blocks for Wire Rope
Type of Block
Width
of
Shell
Thick-
ness of
Block
Capac-
ity
Tons
Sine of
Rope
(Diam.)
Outside
Diam.
Sheave
Weight
Snatch block with hook
Single block with shackle
Double block with
shackle
Triple block with shackle
Quadruple block with
shackle
17
21
21
21
21
21
7N
6
..«
14^
20%
8
10
20
30
40
60.
H
14
14
14
14
14
14
260
250
390
590
820
Six sheave block with
shackle
1,260
American Bridge Co., New York.
Suitable Working Load for Blocks
A suitable working load is not the greatest load a pair of blocks
will sustain, but a load with which such blocks may be used until
worn out. For heavy lifts shackles should be used wherever
possible.
Digitized by VJiOOQLC
REGULAR BLOCKS 649
Regular Blocks— With Loose Hooks
Size
Diameter Rope
2 Singles
2 Doubles
2 Triples
Inches
Inches
Pounds
Pounds
Pounds
5
A
150
250
400
6
H
250
400
650
8
H
700
1,200
1,900
10
l
2,000
4,000
6,000
12
1H.
4,000
8,000
12,000
14
1M
7,000
i 12,000
19,000
Extra Heavy — With Shackles
Size
Diameter Rope
2 Doubles
2 Triples
2 Fourf olds
Inches
Inches
Tons
Tons
Tons
18
2
25
30
40
20
2H
30
35
45
22
2y2
35
40
55
24
3
40
50
70
Wide Mortise — With Loose Hooks
Size
Diameter Rope*
2 Singles
2 Doubles
2 Triples
Inches
Inches
Tons
Tons
Tons
8
1
H
1
2
10
IX •
2
3
4
12
1A
4
6
8
14
W»
6
8
10
16
m
10
12
14
Wire Rope Blocks — Loose Hooks
Size
Diameter of
2 Singles
2 Doubles
2 Triples
Sheave
Tons
Tons
Tons
Inches
8
3
4
5
10
4
5
6
12
5
6
7
14
6
7
8
16
7
8
10
18
8
10
12
y Google
650 SHIP EQUIPMENT
Wibb Rope Blocks — With Shackles
SUe
Diameter of
2 Singles
2 Doubles
2 Triples
2 Fourf olds
Sheave
Tons
Tons
Tons
Tons
Inches
8
4
5
6
8
10
6
8
10
12
12
8
10
12
15
14
10
12
15
20
16
12
15
20
25
18
15
20
25
28
20
20
25
30
30
22
25
30
35
40
24
30
35
40
50
Boston A Lockport Block Co., Boston, Mass.
TACKLES
A combination of ropes and blocks for the purpose of multiply-
ing power constitutes a tackle. Tackles in common use are shown
in Figs. 109 and 110.
Single whip. A single fixed block. No power gained.
Double whip. Two single blocks. Power gained double.
Runner. A single movable block. Power gained double.
Runner and tackle. Two single and one double block. Power
gained eight times.
Gun tackle. Two double blocks.
Luff tackle. A single and a double block, sometimes called a
watch tackle. Power gained three to four times depending on
which is the movable block.
Spanish burton. Two single blocks, one fixed and the other
movable. Power gained three times.
Jiggers. Light tackles for miscellaneous work. Generally a
double block with a tail and a single block with a hook.
Twofold purchase. Two double blocks.
Threefold purchase. Two treble blocks. This is about the
heaviest tackle used. Power gained six to seven times.
Deck tackle. Usually a twofold purchase used for heavy work
on deck.
Let W - weight to be raised
P «= pull or force exerted
Digitized by LiOOQ LC
PULLEYS
661-
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Z
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I £
2jfiere/7f/&/ /*v//ey
Stng/e 3/acA
Figure 100.
V
3
Digiti
^ by Google
652 SHIP EQUIPMENT
Single Fixed Pulley. (See Fig. 109.) Used like a single whip for
raising light weights. The pulley is suspended at R.
P - W
R - p + w - 2P
Velocity of W *» velocity of P
Single Movable Pulley. (See Fig. 109.) Tacks and sheets on
light sails are examples of this form of purchase. One end of the
rope around the pulley is fastened to D.
W - 2P :
* - P - T.
Velocity of W l- % velocity of P
Luff Tackle. (See Fig. 110.) This consists of two sheaves at
A and one at B. The rope is led from B up around one of the
sheaves, A, then down around the sheave B and up over the other
sheave A to P where the power is applied.
W - 3P
12 - 4P
If upper block is fixed then velocity of W = }4 velocity of P
If lower block is fixed then velocity of R = Ji velocity of P
To obtain the greatest advantage with this purchase the lower
block B should be the fixed block.
In a pair of blocks, as in a luff tackle, with any number of sheaves
in either block,
W = total number of ropes at the lower block passing through and
~P attached
jR = total number- of ropes at the upper block passing through and
P attached
Thus in the figure the. number of ropes at the lower block is 3
and the number at the uj?per 4, which according to the rule would
give the same relations between P, R and W as in the above equa-
tions.
Differential Pulley. (See Fig. 109.) Here there areitwo Sheaves at
A fastened together and one at B. ,
R =. radius of large upper pulley !
r = radius of small upper pulley
Then „- = . ■
P R-r
Digiti
zed by GoOgk
OOi/6/e B/oc/c
V
/.ufTac/e/e
Gun TcrcA/e
//?f/e B/dcA
V
fti/0#erj 7acA/e
Figure 110
653
Digiti
zed by G00gk
654 SHIP EQUIPMENT
p r
Velocity of W = 'YW X velocity of P
The loss of power in tackles due to friction and rigidity of the
rope amounts to at least 10% of the load to be raised, for every
sheave used.
In the case of a simple tackle the power gained is represented
by the sum of all the returns which act immediately on the mov-
able block. In a combination of tackles where one acts on the
running end of another, the power gained is found by multiplying
tpgether the value of the several simple tackles. Hence all calcu-
lations relating to tackles can be worked out by the following
formulae.
Let 8 = strain on running end or strain which rope will take
P — power of the tackle
n — number of sheaves
W = weight
The allowance for friction for each sheave in motion
is taken as }/% W
Then 8 X P - W + ^p
A a . • TP (8 + n)
and S or strain on rope =* — Q p —
o X *
Weight (W) that could be lifted - ^8 *P)
Knowing W and S, if required to find the number of sheaves
necessary,
Put P — n if the running end comes off from the standing block
P =s n + 1 if the running end comes off from the movable
block
Hence the sheaves n necessary when the running end comes off the
standing block are - <j pp aQd if off the movable block A
If a snatch block is used to alter the direction of the lead, the
strain on the running end must be found and one eighth added for
the friction of the snatch block. In other words, multiply the
strain on the fall passing through the snatch block by ?.
o
Digitized by LiOOQ LC
CHAIN 655
Example*. A weight of 10 ions is to be lifted by shears with a tackle consisting
of two treble blocks. What is the strain on the running end of the rope?
W - 10 tons; n -3 X2 -6; P-3X2 -6
In the above, if the running end was led through a snatch block to a winch,
what would be the pull on the drum of the winch?
PuU -.M.A X|-2ii x| -gxf-siL*-
A pair of rope blocks with two sheaves in each block lifts a weight of 1H tons.
Find the pull on the end of the rope neglecting friction. One ton ~ 2,240 lb.
With two sheaves in the bottom block, if the weight is raised 1 ft. the pull moves
4 ft. Applying the principle of work, pull X distance it moves = weight X
distance it moves. *
putt X 4 - IX X 2,240 X 1
PuU -fx^fS -8401b.
(Abstracts on Tackles from Practical Marine Engineering and Manual of Sea-
manship.)
CHAIN
The distance from the center of one link to the center of the
next, which is the pitch of the chain, is equal to the inside length
of the link.
To find the weight a chain will lift when reeved as a tackle,
multiply the Ordinary Safe Load General Use in the following table
by the number of parts at the movable block, and subtract one-
quarter for resistance. i
To find the size of chain necessary to lift a given weight, divide
the weight by the number of parts at the movable block and add
one-third for friction; then find from the column of Ordinary Safe
Load General Use the corresponding strain and the size of the
chain. In case of heavy chain, or where the chain is unusually
long, the weight thereof should be taken into account.
The life of a chain can greatly be increased by frequent anneal-
ing and lubricating, and if the wear is not uniform throughout
the length, the chain should be cut and pieced where partially
worn, so that when finally discarded every link shall have done
its full share of work without exceeding the limit of perfect safety.
The diameter of sheaves or drums should not be less than 30
times the diameter of the chain iron used.
Hooks and rings (see Strength of Materials) should be made
from the best hammered iron, and will appear clumsy and out of
Digitized by VjOOQLC
656
SHIP EQUIPMENT
proportion to the size of chain when made to equal its strength.
For instance, a hook for J£-inch chain should be made from 234-
inch iron and will weigh about 20 lb. The ring, if less than 6 ins.
diameter, should be made double the size of the iron in the chain,
and if greater in diameter, the size of iron must exceed this pro-
portion. (Above proportions recommended by Bradlee & Co., Phila.)
Table of Pitch, Breaking, Proof and Working Strains of
Chain*
Dist.
Weight
D. B. G. Special Crane
Crane
From
Center
Foot
Out-
Size
of
Chain
of One
Link to
Center
of Next
in»
Lb.
Approx-
imately
side
Width
Proof
Test
Lb.
Average
Breaking
Strain
Lb.
Ordinary
Safe Load
General
Use
Proof
Test
Lb.
Average
Breaking
Strain
Lb.
Ordinary
Safe Load
General
Use
Lb.
H
»
H
&
1.932
3,B64
1.288
1,680
3,360
1T120
%
i$
1
■1 98
5,796
1.1*32
2,520
-l."40
1,680
3$
m
tit
1186
&372
2.790
3,640
7,280
2,427
ft
1ft
1W
2
6,796
11,592
1864
5,040
10.080
3,360
2H
ltt
7.728-
lo.456
5.152
6,720
R440
4,480
ft
3ft
2
M60
W»S20
'■140
8,400
lri.«00
5,600
8
lgf
4ft
2ft
11.914
23,828
7,042
10,360
2m. 720
6.007
Iff
5
2H
14.490
28,^80
l*,ft60
12,600
J5.200
8,400
8
1H
6ft
6ft
2ft
17.388
34,776
11.592
15,120
:ii'.j40
10.080
2ft
: 86
4f\572
13.524
17,640
35,280
11,7*10
2ft
8^
-'■-!. 184
•il "68
ll.t'89
20,440
4'i.*80
13.627
2ft
9
3ft
3H
25.872
51,744
17L>48
23,520
47,040
15.A80
l
VA
10V*
-".-68
54.136
19.712
26,880
53,760
17,100
lft
IK
ft
12
13^
3ft
33,264
37,576
6W38
75.152
^,176
25.050
30,240
34,160
IV 1.480
Pi-.. 20
20,1«J
3j 7" .
lft
3ft
13ft
4
!ls88
^ 776
27,925
38,080
70.160
25,387
\M
%
16
4ft
46,200
!'J !0O
' 00
42,000
S4.000
28,000
16H
m
50,512
101.024
■ v'74
45,920
01.&40
ao.< i
3ft
WH
4ft
55,748
111.196
37465
50,680
101h36O
3SJBJ
lft
3H
19ft
*H
'.0.368
12ii.736
40,345
54,880
]f«i,760
36,587
VA
3%
23
VA
w.528
13:^056
?! 52
60,480
120. W0
40,3*0
lft
4
25
5ft
7". 762
Ml, 524
47.174
65,520
131,140
43.180
w
4K
28
74.382
14*764
1 ' -88
in
4H
30
5H
7*733
157.466
52.488
IH
4*
31
s2.::20
i '■ 40
1 -80
m
5
33
&A
H i .56
L7<;.-.12
:. .04
VA
5*i
35
1M.360
18* ,720
'■■.•. ''06
m
VA
38
6ft
LO&800
801,800
'7,200
2
h%
40
6^
107,120
2llt40
71 80
2ft
6
43
6H
111,240
22 k. 480
: i60
m
6^
46^
m
121,240
24_!,480
MI.H23
2ft
6^
&A
49H
7ft
12*576
257.152
85,750
2K
52?^
7«
13'.»80
272,160
90,720
2%
&A
58!^
8^
88/6
151,. 180
303.160
101,053
24
7
64H
108*000
33r,,rK)0
112,000
2V8
7^
70
8**
180,544
36].c>88
120,362
2H
7K
73
<m
1^.1(88
3S»076
128,725
2'A
7H
76
9H
306,408
410,616
136,938
3
7*4
86
9^8
217,728
435,456
145,152
* Bradlee & Co., Philadelphia, Pa,
y Google
ANCHORS
657
Chains for hoisting purposes should be made of short links in
order to wrap snugly around drums without risk of bending, and
should have oval sides so that when the chain surges each link
will act as a spring, yielding a trifle.
To find the outside length of any number of lengths, multiply
the inside length of one link by the number of links and add two
thicknesses of the iron.
Tests have shown that the ultimate breaking strength of a chain
with studded links is less than that of an unstudded chain. The
principal function of the stud is to prevent the chain from kinking
and catching.
Swivels are inserted in a chain to prevent the accumulation
of turns as a ship swings around her anchor. There may be three
or four swivels in a cable, the first being about five fathoms from
the anchor. Total length of cable varies from 90 to 200 fathoms.
(See Lloyd's Rules.)
ANCHORS AND ANCHOR DAVITS
There are two types of anchors, viz. stock and stockless. The
latter can be stowed in hawse pipes instead of on billboards on
the deck. All the following anchors except grapnel and mushroom
may be of the stockless type. The number and size of anchors to
Anchors for Yachts and Motor Boats
Size of Boat
No. of
Weight
Weight
Kedge
L. B. D.
Anchors
Bower
30 X 5 X 4
1
50
35 X 8 X 5
1
100
40 X 10 X 5H
2
100
50
40 X 10 X 6
2
110
50
60 X 11 X 6
2
110
50
55 X 11^ X 6
2
120
50
60 X 12 X 6
2
130
50
65 X 13 X 6
2
130
60
70 X 14 X 6H
2
150
60
75 X 15 X 7
2
170
75
80 X 16 X 8
2
200
90
90 X 18 X 10
3
2
250
90
100 X 19 X 12
3
2
325
110
110 X 20 X 13
3
2
400
150
120 X 20 X 13
3
2
400
150
130 X 20 X 13
3
2
450
170
140 X 20 X 14
3
2
450
170
150 X 20 X 14
3
2
500
200
All weights are net.
In accordance with insurance regulations.
y Google
658
SHIP EQUIPMENT
Table of Anchors Required for Steam Vessels
According to their Tonnage, also Number of Anchors and Size of
Cable
Number Required
Weight of Each
Fath-
Ton-
Second
oms
of
Size of
nage
Kedge
Cable
Bower
Stream
Kedge
Bower
Stream
Kedge
Cable
100
2
392
112
105
»
150
2
504
200
120
»
200
2
672
225
120
H
250
2
840
280
120
»
300
2
1008
300
120
1
350
2
1176
336
120
i*
400
2
1
1344
530
*250
135
450
2
2
1512
560
280
135
1A
500
2
2
1680
675
335
150
1M
600
2
2
1848
730
360
150
1A
700
2
2
2016
790
390
165
l*A
800
2
2
2184
900
450
225
165
1A
900
2
2
2380
1000
500.
250
180
l>£
1000
2
2
2600
1120
560
280
180
1A
1200
2
2
2850
1175
580
310
180
1400
2
2
3100
1230
615
310
180
1H
1600
2
2
3350
1350
675
335
180
- Wt
1800
2
2
3600
1450
730
360
180
2000
3
2
3800
1500
760
360
180
2300
3
2
4100
1550
785
390
180
Hi
2600
3
2
4250
1625
.815
390
270
2
3000
3
2
4400
1680
850
420
270
2A
3500
3
2
4600
1800
900
475
270
2H
4000
4
2
4800
1960
950
500
270
1ft
4500
4
2
5000
2130
1050
530
270
5000
4
2
5200
2250
1100
560
270
2A
2H
5500
4
2
5400
2400
1170
585
300
6000
4
2
5600
2520
1250
625
300
1ft
6500
4
2
5800
2650
1320
660
300
7000
4
2
6000
2800
1400
700
300
2A
80Q0
4
2
6300
3000
1500
750
330
2H
9000
4
2
6650
3250
1620
800
330
2tt
10000
4
2
7000
3500
1750
870
360
2%
Size of anchors based on requirements of American Bureau of Shipping.
Digitized by VjiOOQ LC
BOWER ANCHOR
659
Tabus of Anchors Required for Sailing Vessels
According to their Tonnage, also Number of Anchors and Size of
Cable
Number Required
Weight of Each
Fath-
Ton-
Second
oms
of
Sise of
nage
Kedge
Cable
Bower
Stream
Kedge
Bower
Stream
Kedge
Cable
75
2
1
600
170
110
90
1
100
2
1
700
200
110
105
125
2
1
800
225
110
105
150
2
1
900
280
140
• • .
120
i
175
2
1
1000
330
170
120
1A
200
2
1
1100
400
200
120
IH
250
2
1
1300
450
225
ii2
135
1A
300
2
1
1450
500
250
125
135
1M
350
2
1
1625
560
280
140
150
1A
400
2
'1
1850
600
300
155
150
1A
450
2
1
1900
675
340
170
165
m
500
2
1
2125
775
400
195
165
1A
600
3
1
2450
900
450
225
180
1M
700
3
1
2800
1000
500
250
180
2*
800
3
1
3125
1125
615
280
180
900
3
1
3350
1225
650
310
180
18
18
1000
3
1
3575
1250
675
335
180
1200
3
1
3800
1450
725
360
180
1400
3
1
4000
1550
780
395
180
1600
3
1
4250
1600
840
420
180
2
1800
3
1
4500
1800
900
450
180
2
2000
3
1
4700
1900
950
500
180
2A
2500
3
1
5000
2100
1120
560
180
W%
3000
3
1
5400
2350
1230
615
180
2A
3500
3
1
5800
2600
1300
650
180
2H
Size of anchors based on requirements of American Bureau of Shipping.
be carried are given by the classification rules. Below are the names
of the different anchors.
Bower anchor, the heaviest carried, is for anchoring in exposed
positions.
Stream anchor, about one-third the weight of the bower, is for
use in bays and rivers.
Kedge anchor, about one-half the weight of the stream, is for
anchoring in sheltered positions.
ioogle
660
SHIP EQUIPMENT
Grapnel, a small anchor with several flukes, carried by small
yachts and motor boats.
Mushroom anchor has a circular dished end and is only for small
craft.
Anchor Davits. — To get an anchor on deck after it has been raised
above the water by the windlass, a tackle (called a fish tackle)
suspended from the davit or crane (see Fig. Ill) is hooked into an
eye on the shank of the anchor, which is then run up and laid
on the billboard where it is lashed down to ring bolts. Stockless
anchors may be drawn into the hawse pipes, hence do not require
billboards. For calculations for davits see Strength of Materials.
Ml
Figure 111, —Anchor Crane.
Digiti
zed by G00gk
ANCHOR CRANES
661
Sizes of Anchor Cranes
(Lloyd's Requirements)
Weight
of Anchor
including
Spread of Crane in Feet
Stock,
in Cwts.*
9
10
11
12
13
14
15
Diameter of Main Post at Deck in Inches
20
6
&a
6M
6U
m
7
7H
25
6K
WA
7
7M
7H
7H
7%
30
7
7H
7A
7H
7%
8
W
35
7M
7A
7%
8
8
8M
SA
40
7K
7H
8
8H
8A
8M
9
45
8
&H
&A
&H
9
9H
9H
9%
50
SH
&A
&K
9
9H
9H
55
sy2
SH
9
9H
WA
9H
10
60
s%
9
9Ji
WA
9°A
10
10H
♦One cwt. =112 lb.
Corresponding Dimensions of Main Post, Tie Rod and Jib
of Anchor Cranes
Main Post,
Tie Rod,
Jib,
Dia. at Deck, Ins.
Dia., Ins.
Dia. at Middle, Ins.
6
iM
3
6?^
i%
VA
7
2
3j|
7H
iy%
VA
8
2M
2H
4
8H
4^
9
9H
VA
2H
10
2M
5
ioy2
VA
5M
If two tie rods are fitted, the diameter of each is to be % that
of the single rod required.
The steel of which the anchor davits are made has a tensile strength
of 35 tons per square inch with an elongation of not less than 10%
in a length of 8 ins. The davits are to have solid heels and are
to be efficiently strengthened in way of the heads and deck supports.
The following table, from Lloyd's, contains a list of equivalent
sizes of solid and hollow posts.
Digitized by VJiOOQLC
662
SHIP EQUIPMENT
Table of Equivalent Sizes
Diameter at Deck of Solid Wrought Iron Davit
or of Main Posts of Anchor Cranes
Inches
Diameter and Thickness
of Approved Weldless
Drawn Steel Hollow
Boat or Anchor Davit
Inches
3 .
H.
4 .
H.
5 .
H-
X.
6 .
H-
H.
J*.
7 .
u.
8 .
Diameter Thickness
X
X
X
X
X
X
X
4
5*A
6
§K X
6M X
7 X
7H X
7* X
7H X
8Ji X
8^ X
9 X
X
X
9
9% X
ioh x
1034 X
lOJi X
11 X
For fittings see Shackles, Blocks, Bolts, etc.
- -
zedbyGOQg-le
OCEAN STEAMERS 663
LIFE SAVING EQUIPMENT AND ACCESSORIES
The following are abstracts from the U. S. Steamboat-Inspection
requirements for the year 1916:
"Ocean Steamers. — Under this designation shall be included all
steamers whose routes extend. 20 nautical miles or more offshore.
"Coastwise Steamers. — Under this designation shall be included
all steamers whose routes throughout their entire length are re-
stricted to less than 20 nautical miles offshore. Steamers navi-
gating the waters of the Atlantic or Pacific Ocean or the Gulf of
Mexico whose routes are restricted to one nautical mile or less off-
shore shall be included in the class of lake, bay and sound steamers.
"Lifeboats and Life Rafts Required. — All steamers other than
steamers carrying passengers, except as otherwise hereinafter
provided for, shall be equipped with lifeboats of sufficient capacity
to accommodate at one time all persons on board. One-half of
such equipment may be in approved life rafts or approved collaps- .
ible lifeboats.
"All vessels of less than 50 gross tons navigating under the pro-
visions of Title LII, Revised Statutes of the United States, not
carrying passengers shall be equipped with lifeboats or life rafts
of sufficient capacity to accommodate at one time all persons on
board.
"Steamers that are used exclusively as fireboats and belonging
to a regularly organized fire department shall be required to carry
only such boats or rafts as in the judgment of the local inspector
may be necessary to carry the crew.
"Ocean steamers carrying passengers shall be equipped with
lifeboats of sufficient capacity to accommodate at one time all
persons on board including passengers and crew. One-half of such
lifeboat equipment may be in approved life rafts or approved
collapsible lifeboats.
"Coastwise steamers carrying passengers shall be equipped
with lifeboats of sufficient capacity to accommodate at one time
all persons on board, including passengers and crew; Provided,
however, That such steamers navigating during the interval from
the 15th day of May to the 15th day of September in any one year,
both dates inclusive, will be required to be equipped with lifeboats
of only such capacity as will be sufficient to accommodate at one time
at least 60% of all persons on board, including passengers and
crew. Two-thir<Js of such required lifeboat equipment throughout
the year may be in approved collapsible lifeboats.
Digitized by LiOOQ LC
664 SHIP EQUIPMENT
"Working Boat — Steamers of 50 gross tons and upward carrying
passengers shall have one working boat with life lines attached,
properly supplied with oars and painter, and kept in good condition
at all times and ready for immediate use, in addition to the life-
boats required.
"Motor Driven Lifeboats on Steamers. — All ocean steam vessels
of over 2,500 gross tons carrying passengers and whose course
oarries them 200 miles or more offshore shall be required to be
equipped with not less than one motor-propelled lifeboat as part
of their lifeboat equipment; Provided, however, That any vessel
under the jurisdiction of this service may be allowed to carry one
motor-propelled lifeboat as a part of the lifeboat equipment on
such steamer, except that on steamers carrying more than 6 lifeboats
under davits 2 of such lifeboats may be equipped with motors.
"Gasoline may be used for such motors when it is carried only
in seamless steel, welded steel, or copper tanks securely and firmly
fitted in such lifeboats and located where the greatest safety will
be secured.
"All fittings, pipes and connections shall be of the highest stand-
ard and best workmanship and in accordance with the best modern
practice. Storage of gasoline other than in the lifeboats using it
shall not be allowed under any circumstances.
"In computing the cubical capacity of motor-driven lifeboats,
the space required for the engine and fuel shall be excluded.
"Seine Fishing and Wrecking Vessels may substitute a wooden
surfboat or wooden seine boat for a lifeboat.
"Lifeboats and Rafts Required on Inspected Motor Vessels. — All
vessels propelled by machinery other than steam, subject to the
inspection laws of the United States, shall be required to have the
same lifeboat and life raft equipment as steamers of the same class
and local inspectors shall so indicate in the certificate of inspection.
This paragraph shall not apply to such vessels under 50 tons, when
navigating in daylight only, and when equipped with air tanks
under deck of sufficient capacity to sustain afloat the vessel when
full of water with her full complement of passengers on board, or
when properly subdivided by iron or steel watertight bulkheads
of sufficient strength and so arranged and located that the vessel
will remain afloat with her complement of passengers with any
two compartments open to the sea; Provided, however, That no
such vessel shall be navigated upon the waters of t^e ocean without
having on board lifeboat capacity of at least 100 cu. ft.
Digitized by VJiOOQLC
LIFE SAVING APPLIANCES 665
"Lifeboats and Other Equipment Required on Sail Vessels. —
Local inspectors inspecting sailing vessel carrying passengers on
the ocean or on the high seas shall require such vessels to be equip-
ped with a life preserver for every person on board, passengers and
crew, and with lifeboats in accordance with the requirements of
the rule applying to ocean steamers carrying passengers, c
"Lifeboats and their Equipment Required on Seagoing Barges
of 100 Gross Tons or Over.— The lifeboats required on seagoing
barges of 100 gross tons or over shall be at least 14 ft. long and
equipped with a properly secured life line the entire length on each
side, such life line to be festooned in bights not longer than 3 ft.
with a seine float in each bight, at least 2 life preservers, 1 painter
of not less than 2%-inch Manila rope (about .9 inch diameter)
properly attached and of suitable length, 4 oars of suitable length
for size of boat, not less than 4 rowlocks, 1 boat hook properly
secured to staff of suitable length, 1 bucket, and on wooden boats
2 plugs for each drain hole. The row locks and plugs shall be at-
tached to the boat with suitable chain."
"Life Saving Appliances.* — The following table [page 6661 fixes the
number of davits and lifeboats according to the length of the vessel:
"(A) The minimum number of sets of davits to be provided,
to each of which must be attached a boat of the first class.
"(B) The minimum total number of open boats of the first
class which must be attached to davits.
" (C) The minimum boat capacity required, including the boats
attached to davits and the additional boats.
•in vessels which carry rafts there shall be a number of rope
or wooden ladders always available if or use in embarking the persons
onto the rafts.
"The number and arrangement of the boats and (where they are
allowed) of the pontoon rafts on a vessel depend upon the total
number of persons which the vessel is intended to carry; Provided,
That shall not be required on any voyage a total capacity in boats
and (where they are allowed) pontoon rafts, greater than that
necessary to accommodate all the persons on board.
"At no moment of its voyage shall any passenger steam vessel
of the United States on ocean routes more than 20 nautical miles
offshore have on board a total number of persons greater than that
for whom accommodation is provided in the lifeboats and pontoon
life rafts on board.
* Abstract from Seamen's Bill which went into effect in the United States in 1015.
Digitized by VjiOOQ 1C
666
SHIP EQUIPMENT
Registered Length of the Ship
(Feet)
(A)
Minimum
Number
of Sets
of
Davits
(B)
Minimum
Number of
Open Boats
of the
First Class
(C)
Minimum
Capacity of
Lifeboats
100 and
120 and
140 and
160 and
175 and
190 and
205 and
220 and
230 and
245 and
255 and
270 and
285 and
300 and
315 and
330 and
350 and
370 and
390 and
410 and
435 and
460 and
490 and
520 and
550 and
580 and
610 and
640 and
670 and
700 and
730 and
760 and
790 and
820 and
855 and
890 and
925 and
960 and
.995 and
less
less
less
less
less
less
less
less
than 120. .
than 140. .
than 160. .
than 175..
than 190. .
than 205..
than 220. .
than 230. .
than 245. .
than 255. .
than 270. .
than 285. .
than 300. .
than 315..
than 330. .
than 350. .
than 370. .
than 390. .
than 410. .
than 435..
than 460..
than 490. .
than 520. .
than 550. .
than 580. .
than 610. .
than 640. .
than 670. .
than 700. .
than 730..
than 760. .
than 790. .
than 820. .
than 855. .
than 890. .
than 925. .
than 960..
than 995. .
than 1,030
2
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
12
12
14
14
16
16
18
18
20
20
22
22
24
24
26
26
28
28
30
30
2
2
2
3
3
4
4
4
4
5
5
5
5
6
6
7
7
7
7
9
9
10
10
12
12
13
13
14
14
15
15
17
17
18
18
19
19
20
20
Cubic feet
980
1,220
1,560
1,880
2,390
2,470
3,330
3,900
4,500
5,100
5,640
6,190
6,930
7,550
8,290
9,000
9,630
10,650
11,700
13,060
14,430
15,920
17,310
18,720
20,350
21,900
23,700
25,350
27,050
28,560
30,180
32,100
34,350
36,450
38,750
41,000
43,880
46,350
48,750
Digiti
zed by G00gk
LIFEBOATS 667
"If the lifeboats attached to davits do not provide sufficient
accommodation for all persons on board, additional lifeboats of one
of the standard types shall be provided. This addition shall bring
the total capacity of the boats on the vessel at least up to the
greater of the two following amounts.
"(a) The minimum capacity required by these regulations,
"(b) A capacity sufficient to accommodate 75% of the persons
on board.
"The remainder of the accommodation required shall be pro-
vided under regulations of the Board of Supervising Inspectors,
approved by the Secretary of Commerce, either in boats of class
one or class two, or in pontoon rafts of an approved type.
"At no moment of its voyage shall any passenger steam vessel
of the United States on ocean routes less than 20 nautical miles
offshore have on board a total number of persons greater than
that for whom accommodation is provided in the lifeboats and
pontoon rafts on board. * The accommodation provided in lifeboats
shall in every case be sufficient to accommodate at least 75% of the
persons on board. The number and type of such lifeboats and life
rafts shall be determined by regulations of the Board of Super-
vising Inspectors, approved by the Secretary of Commerce; Pro-
vided, That during the interval from May 15th to September 15th
inclusive, any passenger steam vessel of the United States, on
ocean routes less than 20 nautical miles offshore, shall be required
to carry accommodation for not less than 70% of the total number
of persons on board in lifeboats and pontoon life rafts, of which
accommodation not less than 50% shall be in lifeboats and 50%
may be in collapsible boats or rafts, under regulations of the Board
of Supervising Inspectors, approved by the Secretary of Commerce.
"At no moment of its voyage may any ocean cargo steam vessel
of the United States have on board a total number of persons
greater than that for whom accommodation is provided in the life-
boats on board. The number and types of such boats shall be
determined by regulations of the Board of Supervising Inspectors.
"At no. moment of its voyage may any passenger steam vessel
of the United States on the Great Lakes, on routes more than three
miles offshore, except over waters whose depth is not sufficient
to submerge al) the decks of the vessel, have on board a total num-
ber of persons, including passengers and crew, greater than that
for whom accommodation is provided in the lifeboats and pontoon
life rafts on board. The accommodation provided in lifeboats
Digitized by VjiOOQ LC
668 SHIP EQUIPMENT
shall in every case be sufficient to accommodate at least 75% of
the persons on board. The number and types of such lifeboats and
life rafts shall' be determined by regulations of the Board of Super-
vising Inspectors, Provided, That during the interval from May
15th to September 15th inclusive, any such steamer shall be re-
quired to carry accommodation for not less than 50% of persons on
board in lifeboats and pontoon life rafts, of which accommodation
not less than two-fifths shall be in lifeboats and three-fifths may
be in collapsible boats or rafts under regulations of the Board of
Supervising Inspectors, Provided, further, That all passenger
steam vessels of the United States, the keels of which are laid after
July 1, 1915, for service on ocean routes or for service from Septem-
ber 15th to May 15th on the Great Lakes, on routes more than 3
miles offshore, shall be built to carry, and shall carry enough life-
boats and life rafts to accommodate all persons on board including
passengers and crew, And provided further, That not more than 25%
of such equipment may be in pontoon life rafts or collapsible life-
boats.
"The Secretary of Commerce is authorized in specific cases to
exempt existing vessels from the requirements of this section that
the davits shall be of such strength and shall be fitted with a gear
of sufficient power to insure that the boats can be lowered with
their full complement of persons and equipment, the vessel being
assumed to have a fist of 15°, where their strict application would
not be practicable or reasonable.
"Life Jackets and Life Buoys. — A life jacket of an approved type
or other appliance of equal buoyancy and capable of being fitted
on the body, shall be carried for every person on board, and in
addition a sufficient number of life jackets, or other equivalent
appliances suitable for children.
"First. A life jacket shall justify the following conditions:
(a) It shall be of approved material and construction.
(b) It shall be capable of supporting in fresh water for 24
hours 15 lb. avoirdupois ofN iron.
"Life jackets the buoyancy of which depends on air compart-
ments are prohibited.
"Second. A life buoy shall satisfy the following conditions:
(a) It shall be of solid cork or any other equivalent material.
(b) It shall be capable of supporting in fresh water for 24
hours at least 31 lb. avoirdupois of iron.
"Life buoys filled with rushes, cork shavings or granulated
Digitized by vjOOQ LC
CAPACITIES OF LIFEBOATS
669
cork or any other loose granulated material, or whose buoyancy
depends upon air compartments which require to. be inflated are
prohibited.
"Third. The minimum number of lifebuoys with which vessels
are to be provided is fixed as follows:
Total Number
of Buoys
Number
Luminous
Vessels under 100 ft. in length. .
Vessels 100 ft. and under 200 ft.
Vessels 200 ft. and under 300 ft.
Vessels 300 ft. and under 400 ft,
Vessels 400 ft. and under 600 ft.
2
4
6
12
18
2
2
4
9
"Fourth. All the buoys shall be fitted with beckets securely
seized. At least one buoy on each side shall be fitted with a life
line of at least 15 fathoms in length. The lights shall be efficient
self -igniting lights which cannot be extinguished in water, and they
shall be kept near the buoys to which they belong, with the necessary
means of attachment.
"Fifth. All the life buoys and life jackets shall be so placed as
to be readily accessible to the persons on board, their position shall
be plainly indicated so as to be known to the persons concerned.
"Sect. 18. This Act shall take effect as to all vessels of the
United States, eight months after its passage, and as to foreign
vessels 12 months after its passage, except that such parts hereof
as are in conflict with articles of any treaty with any foreign nation
shall take effect as regards the vessels of such foreign nation on
the expiration of the period fixed in the notice of abrogation of the
said articles as provided in section 16 of this Act."
Capacities of Lifeboats. — Measure the length and breadth
outside the planking or plating and the depth inside at the min-
imum depth. The product of these dimensions multiplied by .6
resulting in the nearest whole number shall be deemed the capacity
•in cubic feet. To determine the number of persons a boat is to
carry, divide the result by 10 for ocean steamers as also for lake,
bay, and sound steamers. The carrying capacity (U. S. Steamboat-
Inspection Rules) of a boat 22 ft. long, 6 ft. beam and 2 ft. 6 ins.
deep, as defined above, shall.be determined for ocean, lake, bay
and sound steamers thus:
22 X 6 X 2V2 X .6 198 on
j0 ^ = 20 persons
Digitized by VjiOOQIC
670
SHIP EQUIPMENT
Capacities op Lifeboats
Ocean,
Length
Beam
Depth
Capacity
Cubic
Bay,
Sound
Rivers
Feet
Feet
and Lake
Persons
Persons
12
4 ft. 0 in.
1ft.. 9
in.
60
5
6
14
4 ft. 6 in.
2 ft. 0
in.
76
7
9
14
5 ft. 0 in.
2 ft. 2
in.
91
9
/ll
16
5 ft. 0 in.
2 ft. 1
in.
100
10
12
16
5 ft. 6 in.
2 ft. 4
in.
120
12
15
18
5 ft. 6 in.
2 ft. 4H in.
140
14
17
20
6 ft. 0 in.
2 ft. 6
in.
180
18
22
22
6 ft. 0 in.
2 ft. 7
in.
204
20
25
22
6 ft. 6 in.
2 ft. 9
in.
236
23
29
24
7 ft. 0 in.
3 ft. 0
in.
302
30
37
24
7 ft. 9 in.
3 ft. 4
in.
371
37
46
26
7 ft. 0 in.
3 ft. 0
in.
327
32
40
26
7 ft. 9 in.
3 ft. 4
in.
401
40
50
28
8 ft. 4 in.
3 ft. 7
in.
501
60
62
30
9 ft. 0 in.
4 ft. 0
in.
648
64
81
Lundin Lifeboats. — These are built of galvanized sheet iron,
curved at the ends, having a decked hull with the sides extending
some 15 ins. above the deck. To add to the stability and strength,
the fenders are of Balsa wood which is about 40% lighter than
cork. The U. S. Steamboat-Inspection Rules state: "Lundin
decked lifeboats shall be rated and accepted as lifeboats under
davits, and may be placed in nests of two and under a single pair
of davits. They shall be fully equipped as lifeboats and shall be
measured in accordance with the formula
Cubic capacity = LX#Xl>X.9
Where L = length over all in feet
B = width over all in feet
D = depth from top of keel to top of gunwale ji feet
The carrying capacity of a Lundin lifeboat for installing on
ocean, bay, lake and sound steamers is obtained by dividing the
cubic capacity by 10; that is, allowing 10 cu. ft. to a person. Thus
in a Lundin boat 28 ft. long, 9 ft. 6 ms. beam, and 2 ft. 6 ins. deep,
the cubic capacity = 28 X 9.5 X2.5 X .9 = 598.5 cu. ft., and
the number that can be carried = ^ ' = 60.
10
y Google
COLLAPSIBLE LIFEBOATS
Lundin Decked Lifeboats
671
Length
Feet
Breadth
Feet
Weight, Pounds
Without Persons
Capacity
Persons
24
26
28
30
8
8.7
9.3
10
3,400
4,000
4,600
5,500
40
50
60
75
Engelhardt Collapsible Lifeboats. — These consist of a buoyant
bottom of cork with canvas sides that could be punctured without
sinking the boat. When collapsed, the gunwales are flush with
the flooring, making a broad life raft. In extreme cases they
can be thrown overboard and opened afterwards. When folded
they are about 18 ins. high so that several when placed on top of
each other will not occupy much more space than one of the ordinary
lifeboats. A test was made on a 20-ft. Engelhardt boat with the
bottom plugs removed, and even in this condition it could carry
about- 6,000 lb.
Dimensions and Capacities op Engelhardt Collapsible
Lifeboats
Depth
Length
Width
Number
of
Persons
Carried
of Boat
Extended
Collapsed
Feet
Feet
Inches
Feet
Inches
Feet
Inches
14
5
6
2
8
6
14
16
6
0
2
8
6
18
18
6
6
2
8
6
21
20
7
0
2
8
6
26
22
7
6
2
8
6
30
24
8
0
2
8
6
35
26
8
6
2
8
6
41
28
9
0
2
8
6
47
"Engelhardt collapsible lifeboats may be carried as lifeboats
or life rafts, but not more than 50% of the actual lifeboat capacity
required exclusive of life raft capacity may be substituted by
Engelhardt lifeboats. When an Engelhardt lifeboat is allowed as
■
672
SHIP EQUIPMENT
a lifeboat it shall be carried under the davits with the sides of the
boat fully extended, and only one such boat shall be allowed to
be carried under one set of davits, except that one nest of two
Engelhardt lifeboats shall be allowed to be carried under one set
of davits on each side of steam vessels of 2,000 tons and including
5,000 gross tons, and one nest of three shall be allowed to be carried
under one set of davits on each side of steam vessels of over 5,000
gross tons and when so nested the sides may be collapsed. Whether
carried as lifeboats or as life rafts, they shall be fully equipped
as lifeboats." (Abstract from U. S. Steamboat-Inspection Rules.)
To find the cubic capacity, measure in feet and fractions of a
foot the length and breadth outside the canvas extension, and
the depth inside of the place of the minimum depth taken from the
inside of the bottom planking to the top of the gunwale when ex-
tended. The product of these dimensions multiplied by .7 is the
capacity in cubic feet.
Life Rafts. — All metal life raft cylinders of more than 15 ft. in
length or of more than 16 ins. in diameter shall be constructed of
metal not less than No. 18 B. w. g. Catamaran metallic cylinder
life rafts of approved construction shall allow. for each person
carried \XA cu. ft. of air space for steamers navigating ocean and
coastwise waters.
Metallic Cylinder Life Rafts.
Length
Over
Width
Outside of
Guards
Diameter
of
Cylinders
Number of persons Carried
and Allowed
All
Ocean
River
8 ft. 4 ins.
14 ft. 4 ins.
12 ft. 4 ins.
15 ft. 4 ins.
5 ft. 2H ins.
5 ft. 10}^ ins.
7 ft. 7Hins.
7 ft. 7Hins.
1 ft. 4 ins.
1 ft. 4 ins.
1 ft. 10 ins.
1 ft. 10 ins.
5
8
14
17
7
13
21
26
Life Preservers. — Every vessel inspected under the provisions
of Title LII, Revised Statutes of the United States, shall be pro-
vided with one good life preserver, having the approval of the
Board of Supervising Inspectors, for each and every person carried.
All such life preservers shall be not less than 52 ins. in length when
measured flat, and every cork life preserver shall contain an aggre-
gate weight of at least 5H lb. of good cork, and every life preserver
nvJ^v^
RING BUOYS 673
shall be capable of sustaining for a period of 24 hours an attached
weight so arranged that whether the said weight be submerged
or not there shall be a direct downward gravitation pull upon the
life preserver of at least 20 lb.
Ring Buoys. — The number of ring buoys with which steamers
must be provided (U. S. Steamboat-Inspection Rules) is as follows:
Vessels under 400 ft. in length 12, of which 6 must be luminous;
vessels of 400 ft. and less than 600 ft. 18, of which 9 must be lumi-
nous; vessels of 600 ft. and less than 800 ft. 24, of which 12 must
be luminous.
Ring buoys shall be of cork or any other equivalent material
and shall be capable of sustaining in fresh water a weight of 31 lb.
for a period of 24 hours. They shall be fitted with a line festooned
in bights around the outer edge. One of the buoys on each side
of the vessel shall have a life line attached of at least 15 fathoms.
Luminous buoys are those having attached an efficient self-
igniting light which cannot be extinguished in water.
» Boats Cakried by War Vessels
Launches, heavy boats for carrying men and supplies, often
driven by either steam or gasoline engines.
Cutters, smaller but similar to launches.
Whale boats, different model and lighter than cutters. Have
a pointed bow and stern.
Dinghies, small light boats with square sterns.
Barge, the personal boat of an admiral, only carried on flagships.
Gig, usually a small whale boat.
Galleys, long, narrow boats with a square stern.
Boat Davits
Boat davits must be of sufficient strength for a boat to be lowered
with its full complement, the vessel having an assumed list of 15 degs.
The davits must be fitted with a gear of sufficient power to insure
that the boat can be turned cut against the maximum list under
which the lowering of the boats is possible on the vessel. (U. S.
Steamboat-Inspection Rules.) For strength calculations see Strength
of Materials, Blocks, etc.
Rotating Davits. — These (see Fig. 1 12) are of wrought iron and have
their upper ends curved while the lower part is straight and turns
in a fitting on the deck or on the side of the vessel. To launch
a boat the covers and lashings are removed and the boat raised
Digitized by vjOOQIC
674
SHIP EQUIPMENT
>^'/js*/y^/y^/y^</^<x^v*<>s^WL—
Figure 1 12. — Rotating Davit.
Digitized by VJiOOQLC
XKK£*^0*i»^Z*»****4Va**(VC*
Figure 113. — Pivoted Davit.
675
676
SHIP EQUIPMENT
by tackles to clear the cradle in which it has been resting. The
davits are then swung out, one at a time, bringing the boat clear
of the side. The lowering tackles for large boats have triple sheave
blocks, and those for small, double sheave. The hauling part or
fall passes from the upper block over a small sheave or lug on the
side of the davit and is made fast on a cleat on the davit. The
lower blocks are provided with eyes which engage with hooks, one
at each end of the boat. It is important that both tackles be
released when the boat is in the water, and this is often accom-
plished by slip hooks operated by rods by a man standing in the
boat amidships. In the following table are given sizes of solid
circular davits.
Sizes op Solid Circulak Davits
Sise of.boat
20 ft. X 6 ft.
X 2 ft. 6 ins.
24 ft. X 6 ft. 9 ins.
X 2 ft. 9 ins.
28 ft. X 7 ft. 9 ins.
X 3 ft. 6 ins.
30 ft. X 8 ft.
X 3 ft. 6 ins.
Weight loaded, pounds .
3,360
5,040
8,176
9,632
Radius of davit
4 ft.
4 ft. 6ins.
v 6 ft.
5 ft. 6 ins.
Height of davit
9 ft.
9 ft.
9 ft.
9 ft.
Diameter of davit by
Lloyd's formula
3.7 ins.
4.4 ms.
5.3 ins.
5.6 ins.
Diameter of davit taken
as Vao of the boat's
length
4. ins.
4.8 ins.
5.6 ins.
6. ins.
Pivoted or Mallory Davits. — Here (see Fig. 113) the boats are carried
on skid beams. The davits are usually of an I section with the lower
part pivoted. To launch a boat, the davits are pulled outboard,
being controlled by a tackle until they come against a stop in the
guide frames, when the boat is clear of the side of the vessel and
may then be lowered.
Welin Quadrant Davits. — These (see Fig. 114) are of an I section
curved at the top, while act the lower end is a gear section that
runs in a rack on the base of the frame. When a boat is stowed
permanently the davits are in nearly a vertical position. To
lower a boat the fastenings are first removed, then by turning
screws by means of hand wheels or handles at the davit the boat is
raised and the davits move outboard, thus swinging the boat clear
of the vessel. The time required to launch the heaviest boat is
about one minute.
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WELIN QUADRANT DAVIT
677
23
Figure 114.— Welin Quadrant Davit.
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67S SHIP EQUIPMENT
The two important features in the Welin davit are: (1) the
athwartship traveling motion of the arm, and (2) the compensat-
ing arrangement of the falls thus giving a flattened trajectory
of the boat and a greater reduction of the power necessary for
manipulating it. Compared with a davit pivoted on a stationary
pin, the power necessary for starting it outboard is approximately
15%, and for bringing it back 75%, of the force required to manip-
ulate a gear of that type, all conditions being equal.
Marten-Freeman davits have a cast steel frame forming a track.
A cast steel tandem roller carriage runs on the track which carries
a cast steel boom at the fulcrum, the boom being fastened at its
foot to the base of the frame by a movable link. The carriage,
and with it the boom, travels inboard or outboard by a Tobin
bronze screw operated by a crank, the screw engaging a floating nut
in the carriage. The compensating action of the link tends to
counterbalance the weight of the boat as the boom moves outboard
and to keep the davit in equilibrium at all points.
Angle of Heel of a Vessel when Lowering a Boat or a Weight
Let w = weight of boat in tons
h = distance between stowed and outboard position for
launching
W = displacement of vessel in tons
G M = metacentric height
8 = angle of heel
The center of gravity of the ship will move a distance G Gi
which is equal to — W~~t but G ft — G M X tan 8, hence G M
, « w X h . * w X h
tan 8 = — =~ — or tan 8 =
W " W X G M
Since 8 is generally small, tan 8 = 8
Then 8 = . This gives 8 in circular measure and
to transform it into degrees multiply by 57.
Example. Suppose a boat weighing 18 tons is to be launched from a boom 50 ft.
from its stowed position. The vessel has a displacement of 7,200 tons, and a G M
of 2 ft. Find the angle of heel of the vessel.
tt • *u * i <* w X* 18 X 60 1
Using the formulae = WxQM = 720Q x 2 « ^
or © in degrees - 57 X A - 67/ie = 3H°
y Google
RIGS OF VESSELS
679
To Find the Distance a Lifeboat Will Be from the Side of a
Vessel when the Vessel is Heeled. (See Fig. 115.)
Let
a =
h =
Then
Hence A B
Figure 115.
AB — the horizontal distance the center of the lifeboat
will be from the side of the vessel when the
vessel is heeled to an angle 6
the projection of the overhang or reach of the
davit on the line A C
height of the davit above the deck.
A B = A C X cos 6
A C = a (the overhang of the davit) + h sin 9
(a + h sin 6) X cos 6
RIGS OF VESSELS
Sailing Vessels
Sloop. — One mast with fore and aft sails.
Yawl. — Two masts, main mast stepped farther forward than in
a sloop, with a smaller mast or jigger aft of the rudder post. AH
fore and aft sails.
Ketch. — Two masts, similar to a yawl rig, only the jigger is
forward of the rudder post.
Schooner. — Two or more masts, all with fore and aft sails. This
rig has proved very satisfactory for engaging in the coastwise trade.
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680 SHIP EQUIPMENT
Brig. — Two masts, both square rigged, the main sail being the
lowest square sail on the main mast.
Brigantine. — Two masts, differs from a brig in that the main
sail is a fore and aft sail.
Hermaphrodite Brig. — Same as a brigantine.
bark. — Three masts, foremast and main mast square rigged,
with the mizzen mast fore and aft or schooner rigged.
Barkentine. — Three masts; foremast square rigged, main and
mizzen mast fore and aft.
Ship. — Generally understood to have three masts, viz., fore,
mainland mizzen, all with square sails. Large vessels for engaging
in the overseas trade have four masts, three of which are square
rigged, and the aft or jigger mast schooner rigged.
Steam and Motor Vessels
Those engaging in the coastwise and ocean trades have two or
more masts, each with two or four booms for handling the cargo.
When with four booms, two are forward and two are aft of the
mast. On many vessels derrick posts with booms are installed,
the posts being of steel plates and angles, often serving as venti-
lators to the quarters below. The average cargo boom can handle
about 5 tons. Masts may be of wood or steel, booms usually of
wood. Between the masts are strung wires for the wireless tele-
graph equipment. The masts seldom have sails. As to the rake
of the masts and stacks, generally the rake of each is slightly in-
creased, starting with about Ji in. per ft. for the foremast, % in. per
ft. for the stacks and % in. for the main mast. Many cargo steamers
have no rake to their masts and stack, which are perpendicular to
the water line.
Warships
Battleships, armored cruisers, and sometimes light cruisers have
military masts for observation purposes, with wireless and signal
equipment. Smaller vessels, as torpedo boat destroyers, have two
pole masts with wireless equipment.
See sections on Rope; Blocks; Tackles; and Ship Machinery.
WIRELESS EQUIPMENT
"Every steamer of the United States or of any foreign country
navigating the ocean or the Great Lakes and licensed to carry or
carrying 50 or more persons, including passengers or crew or both,
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STORM OIL 681
must be equipped with an efficient apparatus for radio communi-
cation in good working order, capable of transmitting and receiving
messages over a distance of at least 100 miles, day or night. An
auxiliary power supply independent of the vessel's main electric
power plant, must be provided which will enable the sending set
for at least four hours to send messages over a distance of at least
100 miles day or night, and efficient communication between the
operator in the radio room and the bridge shall be maintained at
all times."
"The radio equipment must be in charge of two or more persons
skilled in the use of such apparatus, one or the other of whom
shall be on duty at all times while the vessel is being navigated.
Such equipment, operators, the regulation of their watches, and
the transmission and receipt of messages, except as may be regu-
lated by law or international agreement shall be under the control
of the master, in the case of a vessel of the United States."
"The choice of radio apparatus and devices to be used by the
coastal stations and stations on shipboard shall be unrestricted.
The installation of such stations shall as far as possible keep pace
with scientific and technical progress."
"Every station on shipboard shall be equipped in such manner
as to be able to use wave lengths of 600 meters and of 300 meters.
The first, viz., 600 meters, shall be the normal wave length."
"Vessels of small tonnage which are unable to use a wave length
of 600 meters for transmission, may be authorized to employ ex-
clusively the wave length of 300, but they must be able to receive
a wave length of 600 meters." (Abstract from Radio Communi-
cation Laws of the United States, 1916.)
STORM OIL
"Ocean and coastwise steam vessels of over 200 gross tons,
navigating the waters of the Atlantic and Pacific coasts and the
waters of any ocean or gulf shall be equipped with oil tanks having
suitable pipes attached for distributing oil overboard whenever
conditions make same necessary.
"Steamers of over 200 and not over 1,000 gross tons shall be
provided with two oil tanks of at least 15 gallons capacity each.
"Steamers of over 1,000 and not over 3,000 gross tons shall be
provided with two oil tanks of at least 20 gallons capacity each.
"Steamers of over 3,000 and not over 5,000 gross tons shall be
provided with two oil tanks of at least 25 gallons capacity each.
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682 SHIP EQUIPMENT
"Steamers of over 5,000 gross tons shall be provided with two
oil tanks of at least 50 gallons each.
"One of these tanks shall be placed in the forward and the other
in the after part of the vessel, and the pipes fiom the oil tanks
shall be led overboard on both sides of the vessel. Tanks shall be
kept filled with animal or storm oil and ready for use at all times."
(Abstract from U. S. Steamboat-Inspection Rules, 1916.)
LINE-CARRYING GUNS, ROCKETS AND EQUIPMENT
All ocean steam pleasure vessels and ocean steam vessels carrying
passengers, except vessels of 150 gross tons and under, shall be pro-
vided with at least three line-carrying projectiles and the means
of propelling them, such as may have received the formal approval
of the Board of Supervising Inspectors (U. S. Steamboat-Inspec-
tion Rules).
The projectiles required to be furnished with each gun shall weigh
not less than 18 lbs., smoothly turned and finished with a windage
of not more than one sixty-fourth of an inch. Service projectile
lines shall be similar in size, to that used by the U. S. Coast Guard,
of not less than 1,700 ft. in length, and capable of withstanding a
breaking strain of 500 lbs., and the projectile end shall be so protected
that the line will not burn when fired from the gun.
The Lyle and Hunt type of guns is approved, and when tested one
round at least shall carry the regular service projectile, with service
line attached, in a still atmosphere a distance of at least 1,400 ft.
without breaking or fouling. The other two rounds shall be fired
with the same charge of powder and the projectile shall have the
same weight as the service projectile, but no line need be attached.
When approved rockets are used instead of guns, there shall be,
in every case, at least three of said rockets, and all steamers that are
required under the law to carry line-carrying projectiles and the
means of propelling them shall be supplied auxiliary thereto with at
least 800 ft. of 3-inch manila line for vessels of over 150 and not over
500 gross tons and 1,500 ft. of said line for steamers above 500 gross
tons; and, except where approved rockets are provided, with three
approved service projectile lines and three projectiles. Such auxil-
iary line and all other equipment shall be kept always ready for use
in connection with the gun and rocket, which lines and other equip-
ment shall not be used for any other purpose.
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1
SECTION X
SHIP OPERATING
LOADING AND STOWING OP CARGOES, OPERATING NOTES
PERTAINING TO MACHINERY (SEE INDEX), MAIN-
TENANCE, SHIP CHARTERING, MARINE INSUR-
ANCE, SHIPPING AND EXPORT TERMS
LOADING AND STOWING OF CARGOES
At present (1917) the legal responsibility for the safety of a
ship rests with the captain. Much legislation has been passed in
regards to the building and running of merchant vessels, but neither
the new laws nor the old ones, with one exception, make any mention
of safe stability. The single exception is the British Board of
Trade, which stipulates that the stability of any passenger steamer
should be sufficient to render her safe. Sometimes the Board of
Trade insists upon additional stability being given to a vessel by
some means or other before granting the passenger certificate.
No definition has ever been advanced as to what the Board con-
siders sufficient stability.
Knowing the cargo capacity of a vessel in cubic feet and the
stowage weight per cubic foot of the cargo to be carried, the tons
of cargo can be calculated. But in making this calculation no
account is' taken of the draft or freeboard, although it is evident
that a vessel with a cargo of iron ore will sink much deeper than
with one of cotton, as the weight per cubic foot of the former is more
than of the latter. On the sides of all vessels classed by Lloyd's,
British Corporation, and Bureau Veritas, there are markings which
indicate the minimum freeboard a vessel can have at certain times
of the year. See section on Freeboard.
Loading. — Even with a freeboard assigned to a vessel, yet the
cargo she carries and the way it is loaded play a most important
part with regard to her stability. While perhaps, when loading a
general cargo which arrives alongside a vessel at all sorts of times,
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G84 SHIP OPERATING
it is difficult to stow everything as might be the best from a stability
standpoint alone, yet care and judgment must be exercised. The
curves of stability (see page 189), if supplied by the shipbuilder,
should be consulted, particularly if the captain is not familiar with
his ship; and if exceptionally heavy weights are to be carried,
approximate calculations should be made as to the trim.
If a vessel is narrow and deep the heavy weights should be placed
low and the light above, thus insuring a comparatively low center
of gravity, as a narrow and deep steamer has a low metacentric
height. If, however, one is broad and shallow, thus having a com-
paratively high metacentric height, the heavy weights should be
placed higher than jn a narrow and deep vessel, thus tending to raise
the center of gravity. Furthermore the weights should be winged
out both longitudinally and transversely, and not all concentrated
in one place. By winging out the weights a vessel, if she has been
designed with sufficient stability, can be made steady in a seaway
and at the same time have ample stability. A high metacentric
height (see page 202) makes a vessel uncomfortable in rough weather,
for she returns to the upright position with a sudden and unpleasant
jerk. War vessels are given a low metacentric height so as to
have a steady platform from which to fire their guns.
While the above applies in a general way to cargoes of all kinds,
yet below are given data on the stowage of oil, grain, coal, and
timber cargoes. When loaded with a cargo of all one material,
and when the vessel is at her load water line, an unfavorable posi-
tion of the center of gravity cannot be changed by moving the cargo,
as by winging out the heavy weights, the only recourse being to
discharge, or leave behind, part of the cargo.
Oil Cargoes. — Oiltightness, structural strength, and stability
are of the greatest importance in vessels carrying oil in bulk.
When a liquid cargo is carried in a closed tank that is kept full,
it may be treated as a homogeneous cargo of the same weight.
However, if the tank is only partly filled, the center of gravity of
the liquid moves from side to side as the vessel rolls, and acts like
a suspended or movable weight, which is a most dangerous con-
dition.
When a vessel is fully loaded a height of from 15 to 21 ins. for
the transverse metacenter above the center of gravity is recom-
mended as a fair allowance for steamers, while from 30 to 36 ins.
for sailing vessels. In loading, adjacent compartments should be
filled simultaneously. This also applies when discharging, for if
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STOWAGE OF OIL IN BARRELS 686
either of the above precautions were not taken a vessel might be
given a serious list with a possibility of her capsizing.
No vessel should proceed to sea with an oil or water ballast
tank partially filled, for free oil or water, is most dangerous, not
only affecting the stability but also the structural strength. Every
captain who is obliged to go to sea with only part of a cargo should
be given a plan or other data as to the tanks that should be filled
with water so as to give the necessary stability and to prevent
any part of his vessel from becoming unduly strained. For a
vessel may be considered as a beam supported at various points
by waves, with the tanks representing the loads coming in many
cases between the points of support. The ideal condition of loading
is that of a uniformly loaded beam, instead of one heavily loaded
at certain points and practically not loaded at all at others.
Refined oil in many instances is shipped in barrels, drums, or
in small cans in cases; thus the loading would be the same as for
any cargo of one material and can be treated as a solid and not
with a free open surface as oil in bulk. When shipped in barrels
and cases, no special structural features such as expansion trunks or
cofferdams are required to be built in the vessel as when carrying
oil in bulk.
The following data are from the Board of Underwriters of New
York, on the loading of petroleum or its products. Vessels so
loading from ports of the United States will be required to conform
to the rules adopted by the Board of Underwriters of New York,
to enable the surveyor to issue the proper certificate.
"In General. — Vessels with cabin or forecastle entirely under
deck, will not be permitted to load crude oil, naphtha, gasoline,
benzine or spirits of petroleum, under inspection.
"Ballast must be of stone or shingle. No sand ballast will be
permitted. The ballast must be leveled fore and aft and well
covered with boards to make an even floor.
"All vessels which are to load petroleum must be sufficiently
stiff, before taking in any oil, to be able to change their berths in
all kinds of weather when tugs can safely tow them.
"All vessels loading barrels or cases, especially those taking
crude oil, benzine, gasoline, naphtha or spirits of petroleum, must
be ventilated through all tjie hatches, unless already fitted with
suitable permanent ventilators fore and aft, to be approved by the
surveyors.
"Stowage of Oil in Barrels. — All barrels mist be stowed bung'
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686 SHIP OPERATING
up, and care must be taken that the chimes are kept free from
the sides of the vessel in the ends.
"No barrel is to be stowed in a place where there is not sufficient
room without bearing its weight on the bilge.
"All barrels must be stowed in straight tiers fore and aft. In
no case will it be permitted to stow with the sheer of the vessel
(rounded off) on the sides.
"The middle of the barrel must be stowed over the four heads
of the barrels in the under tier. This will bring the head of each
barrel to the bung-hole of the under barrel.
"In places where a barrel cannot be stowed, wood or suitable
dunnage should be fitted carefully in order to secure the barrels in
the tier.
"No hanging beds will be permitted under any circumstances.
"The barrels must be stowed bilge and cantline, and every
barrel properly bedded on the floor and well coined.
"In the ground tier each barrel must rest on two soft wood
beds of about one and one-half (\lA) inches in thickness, placed
by the quarter hoops, leaving the bilge of the barrel to be free
from pressure of about one inch.
"No barrel to be stowed athwartships without special permis-
sion of the surveyor, and in no case will it be permitted when the
barrel is subject to any pressure.
"Single deck vessels with hold beams, not more than eight feet
apart from center to center, taking over six heights of barrels
must lay a temporary between-deck with two and a half (2J^) inch
planks, with the ends interlocked, not less than nine inches in
width directly under the bilge of the barrels fore and aft, from side
to side.
"If the beams are closer than eight feet, then two or two and
a half inch plank laid on the beams may be used, from side to side.
"Where the beams are farther apart than eight feet, heavier
material in proportion must be used, all to be regulated by the
surveyor.
"A stanchion well secured at both ends must be' under each
between-deck beam.
"Stowage of Oil in Cases. — In loading ships with full cargoes
of petroleum in cases, it will be required to fill the forward and
after ends of the between-decks, full or nearly full, according to
the trim of the ship, and not to leave spaces there in order to raise
the tiers higher by stowing cases on the flat, especially where the
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STOWAGE OF OIL IN CASES 687
upper tier beam fills or comes near to the deck above. Should the
ship prove to be tender, then the top tier, or a part of it, should
be left out. It is imperative that the cases be kept as low as possible,
so as not to destroy the stability of the ship, especially those that
have nearly perpendicular sides and deep holds.
"The ballast should not be trimmed in the run of the ship, abaft
the two after stanchions, higher than one step for cases above
the ground tier, and from thence forward. If the ballast does not
cover the floor forward, do not use wooden dunnage forward of
the ballast, but stow the cases over one tier of boards, as it only
requires sufficient protection to prevent any vice remaining on the
cargo platform from staining the cases, which would injure their
commercial value at the port of destination. Any excess of ballast
should be stowed in the cantlines between the cases and the bilges
as far forward as practicable. The sides of the cases are to be pro-
tected by boards set up against the sides of the cases.
"The space under the cargo platform between the frames should
be carefully filled with ballast, whereby greater stability of the
ship would be secured when loaded. The first tier must be properly
cross-boarded before the second tier is laid.
"No case should be allowed to rest its weight by its sides, but
must rest easy in its position. All cases must be stowed with
tops up.
"All places oi broken stowage must be filled with wood or other
proper dunnage cut the length of the case. The dunnage must be
clean and dry.
"The amidship part of the tiers must be kept up to prevent
sagging, and the ends of the cases must not lap over and rest on the
next tier.
"In stowing cases on a laid between-deck, laths should be laid
under them to protect them from stains.
"After the cases are stowed as high as the turn of the bilge, laths
must be nailed on the sides, both above and below the beams, or
the between-decks, to prevent the cases from being stained or
chafed.
"Vessels with between-deck beams, if over fifteen feet depth
of lower hold, will be required to lay a between-deck with two and
a half (2%) inch planks, not less than nine inches in width, with
the ends interlocked from side to side to prevent shifting.
"The draft of water will be given by the surveyor.
"When one or more holds and 'tween-decks are completely filled
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688 SHIP OPERATING
with oil and gasoline, naphtha and/or benzine, 8,000 cases of gasoline,
naphtha and /or benzine will be allowed as the maximum amount
to be carried under deck of any one general cargo steamer, it being
understood that when 8,000 cases have been loaded in a hold, no
gasoline, naphtha and/or benzine can be carried in any other inclosed
space, whether that space be a poop, bridge, fore peak or other-
wise.
"Any amount consistent with proper stowage and the stability
of the steamer can be carried on the open deck.1' See also U. S.
Steamboat-Inspection Rules.
Grain Cargoes. — The structural features of a steamer carrying
grain in bulk are practically similar to those of a steamer for general
cargo in the sense that no close riveting (as for oiltightness for
tankers) nor special requirements are called for by Lloyd's or the
American Bureau of Shipping.
Grain cargoes have a tendency to settle down during a voyage,
leaving empty spaces directly under the deck. These spaces have
been estimated at 5 to 8% of the depth of the hold. After the grain
has settled, its upper surface as the vessel rolls tends to become
parallel with the slope of the wave, with the result that if the rolling
is heavy the grain will shift, giving the vessel a list. On the fric-
tion of the particles of grain on each other depends the angle at
which the sliding will take place, which varies with different grain,
as wheat, corn, etc., each have a different angle of repose.
. An investigation made by Prof. Jenkins showed that in a vessel
rolling at sea, the angle at which the cargo begins to shift is less
than the still water angle of repose. In the case of grain with an
angle of repose of 25°, it was found that shifting began at 16 H°-
Prof. Jenkins showed further that the smaller the angle at which
sliding begins, the greater is the stability, but at the same time
pointed out that the effect of a shift of cargo is more serious in a
vessel of small stability than in one with large.
Another point in carrying grain in bulk is that it must be kept
absolutely dry, for when water comes in contact with it, it swells
and has been known to burst the decks of steamers.
The Board of Underwriters of New York have issued rules, which
are given below, for loading grain, and these rules have, received
the concurrence of the Board of Trade, London.
"1. The freeboard shall be measured from top of deck at side of
the vessel to the water's edge at the center of the load water line;
vessels having freeboards assigned by the rules of the Board of
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GRAIN CARGOES 689
Trade (Marine Dept.), London, shall not be loaded deeper than
permitted by those rules.
"2. Shifting boards except as provided for in Rule 11, must ex-
tend from the upper deck to the floor when grain is carried in bulk,
and must be grain tight, with grain tight fillings between the beams,
and are to extend to the top of all amidship feeders. When grain
is carried in bags the shifting boards must extend from deck to
deck in the between-decks, and not less than four feet downward
from the beams in the lower hold.
"3. Shifting boards referred to in all rules shall be of two, (2)
inch yellow pine, or of three (3) inch spruce or equivalent.
"4. All hatch feeders and end bulkheads must be boarded on the
inside.
"5. The grain must be well trimmed up between the beams and
in the wings, and the space between them completely filled.
"6. No coal shall be carried on deck of steamers sailing between
the 1st of October and the 1st of April beyond such a supply as
will be consumed prior to vessel's reaching the ocean.
"7. Care must be taken that when grain in bags or other cargo
is stowed over bulk grain, the bulk grain must be covered with two
thicknesses of boards placed fore and aft and athwartships, with
space between the lower boards of not more than four (4) ft., and
between the upper boards of not more than nine (9) ins. Care must
be taken that all the bags are properly stowed, in good order, and
well filled and that the tiers are laid close together.
"8. Grain in poop, peaks and/or bridge deck must .have such
grain in bags and have proper dunnage and shifting boards.
"9. Steamers having water ballast tanks must have them covered
with a grain tight platform made of 2 J^ or 3 inch sound and dry
planks, but this platform may be dispensed with where the tops
of the tanks are of heavy plates and precautions are taken against
overflow from the bilges.
"10. Steamships without ballast tanks, having a cargo plat-
form in good order, will not be required to fit a grain floor over it,
otherwise such grain floor will be required.
"11. Steamers loading small quantities of grain in lower holds,
not more than one-third (}4) of the capacity of a compartment,
will not be required to have shifting boards. The grain must
have the proper separations as provided for, in Rule 7, arid be se-
cured with cotton or other suitable cargo.
"12. Single deck steamers with a continuous hold forward will
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690 SHIP OPERATING
be required to have a closed bulkhead to divide the same. This
rule will also apply to the after hold.
"13. Shifting boards must be properly secured to stanchions,
or shored every eight feet of length and every five feet of depth
of hold including hatchways. Shores to be three by eight (3 X 8)
ins. or four by six (4 X 6) ins.
" 14. No bulk grain or seeds in bulk (except oats and/or cotton
seed, as provided in Rules 21, 22 and 23) to be carried in between-
decks, nor where a ship has more than two decks, between the two
upper decks, unless in feeders, properly constructed to fill the
orlop and lower hold. Bulk grain may be carried on orlop or third
deck below provided said orlop has wing openings and amidship
feeders to feed same.
"15. Steamers with two or more decks not having sufficient
and properly constructed wing and amidship feeders, will be re-
quired to leave sufficient space above the bulk in lower hold not less
than 5 feet under deck beams to properly secure it with bags or other
cargo, the bulk to be covered with boards as in Rule 7. If an orlop
deck has sufficient openings to the lower hold the orlop and lower
hold may be considered as one hold and loaded accordingly.
"16. Steamers having one deck and beams may carry bulk to
such a height as will permit the stowage over it of not less than
four (4) tiers of bags or other suitable cargo. All bags or other
cargo to be stowed on two tiers of boards as provided for in Rule 7.
"17. Steamers with laid between-decks must have hatchway
feeders, and if the distance in the lower holds, between the forward
bulkhead in said holds and the nearest end of the hatchway feeders
exceeds sixteen (16) feet (unless in the opinion of the surveyor
the distance should be less) then vessel must have a wing feeder
on each side provided in the between-decks to feed this space. If
there are no openings in the between-decks for wing feeders, four
(4) heights of bags must be put on top of the bulk grain from the
bulkhead to within sixteen (16) feet of the feeders. The same
rule applies when the distance between the after end of the hatch-
way feeders and the after bulkhead in lower holds exceeds six-
teen (16) feet.
"18. Bags stowed or laid between decks must be dunnaged.
"19. Steamers of the type known as Turret with single deck or
single deck and beams, may load full cargoes of grain in bulk but
must have shifting boards as required in Rules 2, 3 and 13, and if
required by surveyors trimming bulkheads forward and aft extend-
Digitized by vjOOQ 1C
BUNKER HATCHES 691
ing from deck to floor, or if coming under hatches to top of coaming
as directed by the surveyor, and substantially fitted under their
supervision. The loose grain in the end compartments to be se-
cured by not less than four tiers of bags on boards properly laid
as provided for in Rule 7.
"20. Steamers that are partly single deck and partly double
deck known as switchback and as part awning deck steamers may
load all bulk grain in the lower holds of their double deck com-
partments providing proper midship feeders and wing feeders are
fitted, but the space in the between-decks around the feeders must
be filled with bagged grain or general cargo, but if the vessel is too
deep to carry any grain or other cargo in the between-decks the
feeders are to be shored or properly secured to the satisfaction of
the surveyor.
"If there are no openings in between-decks for wing feeders "and
the bulkheads are more than sixteen (16) feet away from the nearest
end of the midship feeders four (4) heights of bags must be put
on top of the bulk grain from the bulkheads to within sixteen. (16)
feet of the feeders, unless in the opinion of the surveyor the dis-
tance should be less.
"Bunker hatches may be used as feeders when feasible. The
quantity of bulk grain in the feeders must be at least two and
one-half per cent. (2}^%) of the carrying capacity of the hold.
"21. Full Cargo of Oats and/or Cotton Seed. Steamers with
double bottoms for water ballast may carry a full cargo of oats
and/or cotton seed (except as provided for in Rule 8), but if with
two or more decks must have tight wing and hatch feeders to feed
the lower hold or orlop as provided for in Rule 17.
"22. Part Cargo of Oats and/or Cotton Seed. When the quan-
tity of oats and/or cotton seed carried in bulk between the two upper
decks exceeds 60% of the capacity of said deck, the excess over
50% may be stowed in bulk in compartments fitted with wing
shifting boards extending from bulkheads at each end of hold to
within four (4) feet of the hatches, one of such compartments
shall be the largest between-deck compartment; or, where a steamer
has four or more compartments in between-decks oats and/or cotton
seed may be loaded in bulk in all of these compartments if they
are provided with wing feeders of increased size to reach from the
forward and after bulkhead to within four feet of hatches. The
hatch feeders or feeders for lower hold must be capped box feeders,
five or six feet in depth. All holds are to be so fitted.
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692 SHIP OPERATING
"23. In single deck steamers oats and/or cotton seed may be
loaded over heavy grain with proper separations in two holds, but
the grain in all other holds must be properly secured with bagged
grain or other cargo easily handled. This rule applies also to steam-
ers where some holds are double and some single deck.
"24. Modern two-deck steamers with large trimming hatches
may have properly constructed feeders, not to exceed twelve by
sixteen feet.
"25. Stokehold bulkheads and donkey boiler recesses are required
to be sheathed with wood and made grain tight, with an air space
between the iron and the wood, when exposed to heat from fire
room or donkey boiler. When already properly sheathed, surveyor
may pass the vessel, but not unless nine inches of space will be
required where the sheathing is to be erected or renewed. This
rule* applies where the fires are liable to cause damage by excessive
heat from the stokehold or donkey boiler.
"26. Single deck steamers with high hatch coamings loading full
or part cargoes of grain in bulk.
"a. The hatch coamings may be used as feeders and must be of
sufficient size to admit of not less than two and one-half per cent,
of the total gram in the hold being stowed within the coamings;
otherwise the bulk grain must be secured by four heights of bags.
"b. When hatch coamings are utilized for feeders and such
coamings extend into the hold a foot or more below the main deck
such coamings, in the part below the deck, are required to have
two (2) two inch openings in the coamings, between the beams, to
allow the grain to feed into the wings and ends of the hold.
"c. The hatch coamings must be properly supported by heavy
iron cross beams and fitted with fore and aft shifting boards.
"d. The hatch coamings must be so placed that they are capable
of feeding the center and both ends of the holds.
"27. In the event of unusual construction of vessels which
may necessitate deviation from the foregoing rules, the surveyor
must obtain the approval of the Loading Committee of the Board."
For single deck ships, according to the Board of Trade (British),
there shall be either provision for feeding the hold, or there shall
not be more than three-quarters of the hold occupied by grain in
bulk, the remaining one-quarter being occupied by grain or other
suitable cargo in bags, bales, or barrels, supported on platforms laid
on the grain in bulk. For ships with two decks, grain in bulk in the
'tween-decks is for the most part prohibited, but certain grains are
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COAL CARGOES 693
allowed provided there are separate feeders for the holds and 'tween*
decks, or else sufficiently large feeders to the 'tween-decks, and the
hatches and other openings there made available for feeding the
holds. In ships with two decks, longitudinal grain-tight shifting
boards must be fitted where grain is carried either in bags or bulk,
these shifting boards extending from beam to deck and from beam to
keelson, and in the case of bulk grain must also be fitted between
the beams and carried up to the very top of the space.
Coal Cargoes. — Coal is stowed to the shell plating, to the deck
between the beams, and to the bulkhead plating between the stif-
feners. Although coal is a movable material and will shift on
excessive rolling of a vessel, yet it has a larger angle of repose than
grain, and can thus be considered a safer material to carry. In
any case the bunkers (reference is here meant to those not carrying
coal for the boilers) should be entirely rilled, leaving no space be-
tween the top of the coal and the under side of the deck, so that
the coal will not shift when the steamer is rolling.
Attention should be called to the effect of using bunker,. coal
on the stability. In preparing the design of a steamer care must
be taken that she has ample stability both with bunkers full and
empty. In the case of some vessels, as the transatlantic liner
New York, where the bunkers are carried to the upper deck, she gains
in stability as the coal is burned and as she continues on her voyage,
until near the end, for the center of gravity of the coal is above her
center of gravity when leaving port with the bunkers full, and as
the voyage progresses the coal is used; consequently its center of
gravity is constantly being lowered until it is below the center of
gravity of the ship. When about 70% of the coal is burned out in
the New York, the height of the transverse metacenter above the
center of gravity is a maximum, part of this height being due to the
rise of the metacenter.
In some vessels the stability decreases as the coal is burned,
and water ballast must be added to secure the necessary stability.
The Board of Underwriters of New York issue the following
rules in regards carrying coal on deck for use as bunker coal from
ports north of Hatteras to ports south of that latitude: "Steamers
of the Three Deck rule and Spar Deck Vessels are permitted where
the stability and spare buoyancy are guaranteed, to carry during
the winter months, October 1st to April 1st, eight to ten per cent,
of their liet register tonnage of coal on deck for consumption during
the voyage.
.
694 SHIP OPERATING
"Well Deck Steamers. — If the coal is carried on the raised
quarter deck the amount is not to exceed seven per cent, of the
net registered tonnage, but if stowed over the bunkers on the bridge
deck the amount not to exceed five per cent, of the net registered
tonnage.
"Bulwarks to be sealed up leaving a clear water course to the
scuppers and other openings. Steering gear to be free of any
obstructions.
"Sufficient coal to be put in bags to secure the ends and cover
the loose coal, the same not to be higher than the rail.
"Where suitable bins are provided of a moderate size the coal
in bags may be omitted.
"Grain laden vessels are not permitted to carry coal on deck
beyond sufficient to carry them to open sea. Vessels other than
those described are to be submitted to the Loading Committee."
Lumber Cargoes. — For carrying lumber in the coastwise trade
schooners are largely employed, but for long routes as from the Pacific
to Atlantic ports via the Panama Canal steamers are used. In
schooners the lumber is carried both in the hold and on the deck,
while in steamers usually in the holds with perhaps a small deck
load. When the lumber is mixed, satisfactory conditions as to
stability can be obtained by the proper distribution of the light
and heavy lumber, and winging out the weights as previously
mentioned.
Steamers engaging in the lumber trade should be broad in pro-
portion to their draft thus giving a fairly high position of the meta-
center and sufficient margin of stability without resorting to ballast,
particularly when carrying a heavy deck load. Such a deck load,
if well fastened in place, gives valuable surplus buoyancy. On the
Pacific Coast the deck load is secured by chains fastened to the sheer
strake and extending over the load from side to side with turn-
buckles to take up the slack.
The Board of Trade (British) imposes a fine not exceeding £5
for every 100 cu. ft. of wood carried as deck cargo which arrives
in a ship, British or foreign, in any port of the United Kingdom
between October 31 and April 16, provided no unforeseen circum-
stances, as defined in the Merchant Shipping Act of 1906, intervene.
By "deck cargo" in the above sentence is meant any deals, bat-
tens, or other wood goods of any description to a height exceeding
3 ft. above the deck. •
For Carrying Horses and Cattle shelter deckers are particularly
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CARRYING DANGEROUS ARTICLES 695
suitable. The U. S. Department of Agriculture publishes a special
circular on the subject. For weights and costs see page 330.
For Loading Calcium Carbide, which must be done under the
supervision of a surveyor, see Regulations issued by the Board of
Underwriters of New York.
Regulations for Carrying Dangerous Articles (Sec. 4472, U. S.
Steamboat-Inspection Rules, 1915). — "No loose hay, loose cotton
or loose hemp, camphene, nitroglycerin, naphtha, benzine, benzole,
coal oil, crude or refined petroleum or other like explosive burning
fluids or like dangerous articles, shall be carried as freight or used
as stores on any steamer carrying passengers; nor shall baled cotton
or hemp be carried on such steamers unless the bales are compactly
pressed and thoroughly covered and secured in such manner as
shall be prescribed by the regulations established by the board
of supervising inspectors with the approval of the Secretary of
Commerce, nor shall oil of vitriol, nitric or other chemical acids
be carried on such steamers except on the decks or guards thereof
or in such other safe part of the vessel as shall be prescribed by the
inspectors.
"Refined petroleum, which will not ignite at a temperature
less than 110° F., may be carried on board such steamers upon
routes where there is no other practical mode of transporting it,
and under such regulations as shall be prescribed by the board of
supervising inspectors; and oil or spirits of turpentine may be
carried on such steamers when put up in good metallic vessels or
casks or barrels well and# securely bound with iron and stowed in
a secure part of the vessel; and friction matches may be carried
on such steamers when securely packed in strong, tight chests or
boxes, the covers of which shall be well secured by locks, screws
or other reliable fastenings, and stowed in a safe part of the vessel
at a secure distance from any fire or heat. All such other pro-
visions shall be made on every steamer carrying passengers or freight,
to guard against and extinguish fire, as shall be prescribed by the
board of supervising inspectors.
"Nothing in the foregoing or following sections of this Act shall
prohibit the transportation by steam vessels of gasoline or any
of the products of petroleum when carried by motor vehicles (auto-
mobiles) using the same as a source of motor power; Provided,
however, that all fire, if any,' in such vehicles or automobiles be
extinguished immediately after entering said vessel, and that the
same be not relighted until immediately before said vehicle shall
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606 SHIP OPERATING
leave the vessel; Provided further, that any owner, master, agent,
or other person having charge of passenger steam vessels shall have
the right to refuse to transport automobile vehicles the tanks of
which contain gasoline, naphtha or other dangerous burning fluids.
"Provided, however, that nothing in the provisions of this Title
shall prohibit the transportation by vessels not carrying passengers
for hire, of gasoline or any of the products of petroleum for use
as a source of motive power for the motor boats or launches of
such vessels. Provided, further, that nothing in the foregoing
or following sections of this Act shall prohibit the use by steam
vessels carrying passengers for hire, of lifeboats equipped with
gasoline motors, and tanks containing gasoline for the operation
of said motor-driven lifeboats; Provided, however, that no gasoline
shall be carried other than in the tanks of the lifeboats; Provided
further, that the use of such lifeboats equipped with gasoline mo-
tors shall be under such regulations as shall be prescribed by the
board of supervising inspectors.
"Nothing in" the foregoing or following sections of this Act shall
prohibit the transportation and use by vessels carrying passengers
or freight for hire of gasoline or any of the products of petroleum
for the operation of engines to supply an auxiliary lighting and
wireless system independent of the vessel's main power plant;
Provided further, that the transportation or use' of such gasoline
or any of the products of petroleum shall be under such regulations
as shall be prescribed by the board of supervising inspectors with
the approval of the Secretary of Commence."
Machinery Operating.— See Index.
MAINTENANCE
Hull
In General, on the maintenance of a vessel largely depends not
only her class with the classification societies, but also the rate given
to her by the marine insurance underwriters.
Lloyd's Rules state: "Vessels intended for classification in
the Register Book are to be built under the Society's special survey,
and vessels so built will be entitled to the mark *J* in the Register
Book. To entitle steel vessels to retain the characters assigned to
them, they are required to be subjected to periodical special surveys
designated No. 1, No. 2 and No. 3. These surveys become due in
the cases of vessels classed 100A or 90A at 4, 8 and 12 years
Digitized by vjOOQ IC
<
MAINTENANCE 697
respectively from date of build, and subsequently at the expiration
of like periods from the date recorded in the Register Book of the
previous special survey No. 3. Vessels class A for special purposes
are required to be subjected to special surveys No. 1, No. 2 and
No. 3, at 3, 6 and 9 years respectively from date of build, and at the
expiration of like periods from the date recorded in the Register
Book of the previous special survey No. 3."
The American Bureau of Shipping Rules state: "Vessels of the
highest class (Al for 20 years) must be surveyed five years from
date of launching and every four years thereafter. Those of the
second class (Al for 16 years) and third class (Al for 12 years) built
under special survey and all others at the expiration of four years
from date of launching, and every three years thereafter."
Attention should also be called to the navigation laws of the
United States pertaining to American ships, as per the following
rules: "The local inspectors shall once in every year, at least,
carefully inspect the hull of each steam vessel within their respec-
tive districts, and shall satisfy themselves that every such vessel
so submitted to their inspection is of a structure suitable for the
service in which she is to be employed, has suitable accommodations
for passengers and crew, and is in a condition to warrant the belief
that she may be used in navigation as a steamer, with safety to life,
and that all the requirements of law in regard to fires, boats, pumps,
hose, life preservers, anchors and other things are faithfully com-
plied with; and if they deem it expedient they may direct the vessel
to be put in motion, and may adopt any other suitable means to
test her sufficiency and that of her equipment. The local in-
spectors shall once in every year, at least, carefully inspect the hull
of each sail vessel of over 700 tons carrying passengers for hire and all
other vessels and barges of over 100 tons burden carrying passengers
for hire within their respective districts. Vessels while laid up
and dismantled and out of commission may, by regulations estab-
lished by the Board of Supervising Inspectors be exempted from
any or all inspection as outlined above and in sections 4418, 4426
and 4427.
"The local inspectors of steamboats shall at least once in every
year inspect the hull and equipment of every seagoing barge of 100
gross tons or over, and shall satisfy themselves that such barge
is of a structure suitable for the service in which she is to be em-
ployed, has suitable accommodations for the crew, and is in a con-
dition to warrant the belief that she may be used in navigation
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398 SHIP OPERATING
with safety to life. They shall then issue a certificate of inspection
in the manner and for the purposes prescribed in sections 4421 and
4423 of the Revised Statutes of the U. S. Every such barge shall
be equipped with the following appliances of kinds approved by the
Board of Supervising Inspectors. At least one lifeboat, at least
one anchor with suitable chain or cable and at least one life pre-
server for each person on board."
Details. — When the outside plating has butt straps instead of lap
butts the bilge strake butts may show signs of working, with the .
result the plates are slightly drawn apart, and in the opening thus
formed corrosion begins. To prevent corrosion, the seam should be
filled with metal packing or cement, or if the plates are badly cor-
roded an additional butt strap should be riveted on the outside.
Due to the straining of a vessel in a seaway, the wood deck may
begin to leak, in which case the plank seam or seams in way of
the leak should be caulked from butt to butt. An easy way to
tell if a deck leaks is to watch it drying after it has been well flushed
with water.
Particular attention should be paid to the bilges, for here water,
parts of the cargo, and rubbish are found. This combination
of refuse corrodes the margin plate and the shell plating, as also
the frames. To prevent this waste material from getting into the
bilges, steel plates may be riveted to the reverse frames or wood
ceiling fastened thereto, in which are hatches for giving access to
the bilges.
The fore and aft peak tanks should be kept dry as far as possible,
and be ventilated. If the tanks are used for trimming, then all
crevices should be filled with cement or painted with a bitumi-
nous compound.
The proximity of certain metals (brass or copper) to iron or
steel may set up galvanic action when in salt water. Hence with
bronze propellers or with brass stern bearings, unless zinc strips are
fastened to the stern frame severe pitting of the sternposts may
result.
To prevent galvanic action between the shell plating and sea
valves, cast zinc rings are fastened in the apertures of supply and
discharge pipes below the water line. The composition fittings
which pierce the hull below the water line might be coated with
an enamel paint that is impervious to sea water, so that when the
valves are closed there will be no action between them and the
shell plating.
Digiti
zed by G00gk
THE LIFEBOATS 699
The corrosion throughout the double bottom is comparatively
slight except under the boilers. Here the heat from them and the
moist stagnant air create a condition that is favorable to rapid
corrosion. Thus the tank top plating is increased in thickness
under the boilers by the rules (Lloyd's, British Corporation, etc.),
and furthermore the compartments should be well ventilated if
possible. In laying out the boiler room, the boilers should be a
sufficient height above the tank top for easy access.
The floors and longitudinals may be covered with a bituminous
compound or special paint, some shipyards galvanizing the boiler
room floors.
In making a hull survey, the condition of the coal bunker bulk-
heads should be noted, particularly around the boilers, for coal
when loaded wet into a hot bunker gives off acids that attack
and eat away steel plates and angles.
The lifeboats should be swung out at regular periods or at least
their blocks and tackles should be gone over, as well as the rigging.
When a vessel is docked her sea valves should be opened up
and stern bearings examined to see if they have been worn downf
If the bearings have been worn down, then new strips of lignum
vitae should be put in them. The rudder bushings should also
be examined, and the coupling bolts on the palm.
To protect the nuts on the bolts securing the propeller blades
to the hub, the nuts are often covered with cement.
When in dry dock the plugs in the shell plates on the bottom
should be unscrewed so that water can be drained from the inner
bottom, or if a vessel has no such plugs then a few rivets should be
drilled out.
Painting, see page 279.
Docking. — The number of times a vessel is docked in a year
depends on the water in which she runs; in the tropics perhaps once
every six months; elsewhere it may be once a year.
Prior to docking a vessel a docking plan should be given to the
dock superintendent if he is not familiar with the underwater
form of the vessel. The plan consists of a longitudinal section
with the transverse bulkheads and engine and boiler spaces indi-
cated as well as the sea connections. At various points cross
sections are taken showing the form of the vessel, from which can
be determined the blocking required. Before a vessel enters a
graving dock, care must be taken that the dock is large enough for
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700 SHIP OPERATING
the vessel to float in, and that there are no projections at the en-
trance to foul or damage her.
I The longitudinal spacing of the keel blocks is generally 3 to 4 ft.
apart, but the distance depends on the weight of the vessel per foot,
some requiring additional shoring at the bilges. In one with a
considerable part of the keel not in a straight line, the blocks must
be close together at the ends and additional ones placed to take the
overhang. Side blocks should come under all parts where the
weights are concentrated, but they must not interfere with the
sea connections. Sometimes in graving docks side shores are
necessary, that is, shores from the sides of the vessel to the walls
of the dock. In floating docks such shores are not possible and
instead the side blocks are placed nearly to the turn of the bilge
of the vessel.
Machinery
No matter how careful a company may be in watching the con-
sumption of coal, oil, and other supplies, all the money so saved
can easily be wiped out if the many little repair jobs are not promptly
looked after, if possible at sea, or reported when the vessel arrives
at port so that they can be attended to then.
The above applies to both the hull and the machinery but par-
ticularly to the machinery. Some steamship companies insist
that everything that is broken or missing must be reported to the
shore superintendent, with the result that the repair bills for the
annual overhaul are kept at a minimum and the vessels are in
good condition all the time. All minor repairs should be attended
to at once, as, for instance, if a boiler seam begins to leak, promptly
caulk it, or if a pipe flange starts leaking, at the first opportunity
tighten up the bolts or put in a new gasket.
In making out requisitions or specifications for repairs state
exactly what is to be done. Instead of calling for a general over-
hauling, say, of a pump, itemize, as, for example, if the valve stems
need renewing, or the water cylinder should be rebushed.
Lloyd's Rules state in part: "The machinery and boilers of
all steamships and the donkey boilers of sailing vessels are to be
surveyed annually if practicable, and in addition are to be sub-
mitted to a special survey upon the occasions of the vessels under-
going the special periodical Surveys 1, 2 and 3 prescribed in the
Rules, unless the machinery and boilers have been specially sur-
veyed within a period of 12 months. The tail shaft is to be exam-
yGoogk
INDICATOR CARDS 701
ined annually and drawn at intervals of not more than two years.
On the application of owners, the Committee will be prepared to
give consideration to the circumstances of any special case."
The U. S. Steamboat-Inspection Rules state "that if the tail
shaft has a complete brass bushing the shaft can go for 3 years
without being withdrawn for examination."
Quoting from the American Bureau of Shipping: "When
periodical surveys are made, all the principal working parts of the
machinery are to be carefully examined. Propeller shafts and
bushes are to be drawn for examination at least once in every two
years, and the adjustment and condition of all cranks and crank
pins, journals, couplings, etc., should be carefully examined. The
periodical surveys of machinery should as far as possible be made
to conform with the periodical surveys of the hulls. In no case,
however, will the time between the surveys of machinery exceed
that prescribed for the hulls."
By taking indicator cards of the engine, these will give infor-
mation if the valves are correctly set. The cylinder covers should
be removed every three or four months and the inside of the cylin-
ders examined, as also the piston rings. A little vaseline or graphite
in the cylinders tends to make a good wearing surface. The thrust
collars should be looked at as also the main engine bearings and
the oiling system.
If any of the steady bearings have been running hot, perhaps
the shafting is out of line, which should be checked up when the
vessel is in port. Hot bearings in most cases are due to the cap
being set up too tight, or insufficient lubrication. If a bearing
is running hot, give it plenty of oil, and if it still continues to run
hot, slack off the nuts. As a last resort use the water service, and
then just enough water to keep down the heat.
The water ends of air, feed, and bilge pumps should be examined
frequently to see that the valves have not become excessively worn
or the springs broken.
The life and efficiency of the boilers depend on the care taken
of them. The water should be kept at a constant height above
the crown sheet, and furthermore the fires should be cleaned at
regular periods (see Overhauling Boilers). Only in case of necessity
should the engine be suddenly reversed or the throttle closed quickly,
for by so doing there is caused a sudden back pressure in the boiler
and piping. 'To prevent galvanic action, zinc plates are placed
in baskets inside the boiler, or compounds used in the feed water.
Digitized by VjiOOQ 1C
702
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Engine
Time Account per S. S.
Coal Account
Coals remaining in bunkers on arrival at
received at
Total.
Tons
Quality
Consumption days steaming at tons per day
Average speed per hour throughout knots
Date
Distance
Run per
Day in
Miles
Revolu-
tions
of
Engine
Daily
Consump-
tion
Time and
Cause
of
Stoppages
Summary
Coal received Total
Consumed by main boilers Tons
" " donkey "
" " galley and ship "
Own use
Remaining on board
tons
Remarks
tons
tons
y Google
CHARTERING > 703
In several sections are notes pertaining to the care of condensers,
pumps, etc. (See Index.) Most companies require their engineers
to keep a record of the coal consumed, revolutions of the engines,
etc., as per form on page 703.
CHARTERING
There are three ways of chartering a vessel: (1) individual trip
charters; (2) contracts for the movement of some specified quantity
of cargo in a stated period or number of trips; and (3) time charters.
(1) In trip charters it is generally agreed that the owners shall
receive freight based upon some agreed rate on the cargo cairied,
for instance, so much per case of oil, or so much per ton of ore;
or instead of such a rate some definite lump sum for a voyage.
Among other conditions that are settled in negotiations are
the number of days to be allowed merchants for loading and dis-
charging the cargo, these days being technically known as lay days,
and it is also generally agreed that if the merchants delay the
steamer beyond the number of lay days allowed they shall pay
the owners a penalty, which is referred to as a demurrage, at some
agreed rate for every day delayed.
In trip charters the loading port may be definitely named or
the merchant may be given the option of loading at any one of
several ports mentioned, orders for which port are to be given
prior to the steamer's readiness to leave her last port of discharge;
or it may be arranged that she is to proceed to some port of call
for orders as to her loading port.
The discharging port may also be definitely agreed on, or the
merchant may be given the right of ordering the steamer to any
one of the various ports named for discharge, and it is sometimes
agreed that the merchant may order the steamer to a second and
possibly a third port of discharge by paying some agreed extra rate.
It is also arranged in negotiation just when the steamer is to be
ready for loading; that is to say, two dates are mentioned between
which the vessel must report. The first date is known as the date
before which lay days cannot commence, so that if the steamer
tenders any time before a certain date she cannot demand the cargo.
The second date is known as the cancelling date. A clause is in-
serted in the charter reading: "Lay days are not to commence
before unless with the charterer's permission and should
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704 SHIP OPERATING
steamer not be ready at loading port before the charterers
are to have the option of cancelling the charter."
(2) Contracts for the Movement of some specified quantity of
cargo in a stated period or number of trips. This may be negoti-
ated with owners who have a sufficient number of steamers to put
out one at regular intervals for carrying a specified cargo, or a
contract may be made with speculating contractors who hope to
charter steamers from time to time as necessary and work out a
profit, or a contract may be made for some definite steamer to make
an agreed number of consecutive voyages.
(3) Time Charter. — In delivering the steamer the owners furnish
her with a complete crew and thoroughly equipped and ready for
business, but pay no expenses incidental with the loading and
discharging of the cargo or going into or proceeding from ports,
nor for the motive power for the vessel at sea, that is, the coal
burned, but they must keep the steamer in good condition and
furnish the necessary provisions, etc., for the maintenance of the
crew, and the necessary stores for the proper upkeep of the steamer.
Besides the port of delivery being agreed on when the charter
is negotiated, it is also stipulated what the period of charter shall
be, where the vessel is to be redelivered by the charterers to the
owners, and within what limits the charterers may employ the vessel,
also the dates between which the vessel must be ready for delivery,
and the rate of hire.
Thus the owners furnish the vessel and pay the crew's wages,
provisions, and stores, and maintain the vessel in a thoroughly effi-
cient condition, while the charterers pay practically all other ex-
penses as for coal, various port charges as government dues, light-
house dues, wharfage, stevedoring, loading and discharging the
cargo, watchmen for the cargo, towages, pilotages, and also in
some cases the marine insurance and the war risk.
[Above paragraph contains data from L. L. Richards of Bowring & Co., New
York.]
Charter Forms. — A form of time charter used by the U. S. Navy
Department is given below and illustrates in a general way time
charter forms. It is, however, customary to insert a clause giving
particulars of the steamer, as her gross and net tonnage, tons dead-
weight including bunkers, cubic feet capacity in grain or bale
measurement, bunker capacity, speed and coal consumption.
In the United Kingdom there are two forms, viz. Baltic and
White Sea Conference Uniform Time Charter (1912), for European
Digitized by VJiOOQ LC
CONDITIONS OF TIME CHARTER 706
Trade, and the Chamber of Shipping Time Charter (1902). The
former is known by the code name Baltime, and contains a paragraph
stating in part "that the steamer shall be redelivered at ice free
port in charterer's option in the United Kingdom or on the Con-
tinent between Havre and Hamburg both included.,, On account
of the war in Europe since 1915 this has been modified.
In the Chamber of Shipping Time Charter (1902), known as
Timon, the redelivery port can be anywhere mutually agreed upon
and there is a paragraph stating that "the charterers can require
after a certain time (previously agreed upon) the owners to dry
dock the vessel arid paint her bottom." Printed forms of Baltime
and Timon may be purchased, but because of the European War
many special clauses are added.
CONDITIONS OF TIME CHARTER*
1. Under this opening, tenders are also solicited for one to three vessels on time
charter, for a period of from three to six months, at charterer's option; the follow-
ing conditions to govern in the case of each vessel:
2. The vessel to be used for the transportation of/ or, at charterer's option.
3. Payment to be made at a flat rate per calendar day for the time actually
under charter, payable at the end of each month or as soon thereafter as may
be practicable.
4. Owners shall pay all charges and expenses incident to the operation and
maintenance of the vessel, except the item of coat, in the case of which the char- '
terers shall accept and pay for all coal in the steamer's bunkers at the commence-
ment of the hire, and the owners shall, at the expiration of the charter, pay for
all coal left in the bunkers, each at -the current market price at the respective
ports where the hire begins and ends. All coal used by the vessels for bunker pur-
poses will be furnished by the charterer.
5. The only cost in connection with this charter to be borne by the charterer
will be the per diem rate asked by the owners of the vessel, plus the cost of the
coal consumed, necessary pilotage fees and, in the case of passage of the vessel
through the Panama Canal, the usual canal tolls; all other expenses and charges
to be defrayed by the owners. Expense of loading and discharging cargo to be
borne by the charterer.
6. The charterer shall pay for the use and hire of the vessel commencing
at seven A. M. on the first legal working day following the day of delivery at
loading port (unless otherwise mutually arranged), the vessel then being ready
to receive cargo and tight, staunch, strong and in every way fitted for the service,
with a clean and clear hold, notice whereof to be given to the charterer before
five P. M. on a working day. Hire to continue from the time specified for com-
mencement of charter until the vessel's redelivery to the owners at a port to be
agreed upon at the time of execution of contract. Owners to take all steps nec-
essary for the proper care of vessels while under charter, with the understanding
that the charterers are to repair proven damages caused through the charterer's
* A foim that has been used by the U. S. Navy Dept.
Digitized by LiOOQ IC
706 SHIP OPERATING
negligence or fault beyond ordinary wear and tear, but not to pay for time occu-
pied by such repairs.
7. All steam winches and steamer's tackle to be at charterer's disposal at
all times during loading and unloading, by day and night, and sufficient steam to
be furnished to effectively run all winches at once. Steamer to work day and
night, if required by charterers. Steamer to find sufficient competent men, at
ship's expense, to tend winches or similar work, both day and night, if required.
No overtime of any nature to be paid by the charterer. In the event of short steam
or disabled winches or boilers, the owners to pay for such shore faculties as might
be required to effectively load or discharge cargo.
8. The whole reach of the vessel's holds, decks and usual places of loading
shall be at the charterer's disposal.
9. The owner shall be responsible that the vessel prosecutes its voyages with
the utmost despatch and shall render all assistance with the ship's crew and boats;
that the captain (although appointed by the owners) shall be under the orders
and direction of the charterer and that if the charterer shall have reason to be
dissatisfied with the conduct of the captain or any of the officers or crew the owners
shall, on receiving particulars of the complaint, investigate the same and if char-
terer insists, make changes in the appointment.
10. The Master shall be furnished from time to time with all requisite in-
structions and sailing directions; shall keep a correct log of the voyage or voyages,
which are to be patent to the charterer or its agents, and copy furnished if requested.
When, on account of any accident to steamer or for any other reason the steamer
shall be off hire, the Master shall furnish written advices to charterer whenever
steamer is off hire, stating the cause of same, and when service is resumed, make
special report to charterer, giving particulars of such time off hire and also advices
of quantity of bunkers consumed during said period.
11. That any loss of time from deficiency of men or stores, or from any defect
or breakdown of machinery, steering apparatus, etc., or damage from fire, col-
lision, stranding or damage which prevents the working of or continuance on
the voyage of the vessel for twelve hours or more shall be for account of owners
and in such case the payment of hire shall cease from the commencement of the
loss of time till she again resumes actual service for charterer, tight, staunch,
and strong, and in every way fitted at the place of accident, or should the vessel
put baek from any of the above-mentioned causes or put into any other port
than that to which she is bound, the hire shall be suspended from time of her put-
ting back or putting in until she be again in the same position and the voyage
resumed therefrom, and the pilotage fees at such port shall be borne by steamer's
owners. Also, if any loss of time is incurred through fault of ship, after cargo
and coals are on board, or cargo discharged and ship ready for sea as far as char-
terer is concerned and hour of sailing has been fixed by charterer and notice given
to Captain, if he is on board, if not, to the officer in charge at the time, such lost
time is to be for steamer's account; but should the vessel be driven into port or
anchorage through stress of weather, or from any accident to the cargo, such de-
tention or loss of time shall be at the charterer's risk and expense. If upon the
voyage the 'steamer's speed be reduced by breakdown of machinery or other casu-
alty, the time lost and the cost of the extra coal, if any, consumed in consequence
thereof, shall be borne by the owners.
12. Charterer reserves the right to cancel this charter should steamer meet
with any casualty causing her to be withdrawn from charterer's service tempo-
rarily or permanently. It is to be mutually agreed that this charter shall be sub-
Digitized by vjiOOQ LC
NOTES ON CHARTERING 707
ject to all the terms and provisions of and all the exemptions from liability con-
tained in the Act of Congress of the United States approved on the 13th day
of February, 1893, and entitled "An Act relating to navigation of vessels, etc."
13. Master to accomplish all bills of lading for cargoes delivered on board
vessel, his signature being accepted as binding on the owners.
Notes on Chartering* (
1. The first point for owners is to stipulate for (a) delivery of
the vessel being accepted where she lies, after completion of dis-
charge, or dry docking and repairs, so that the vessel may be placed
on hire forthwith without loss of time or expense incidental to a
ballast shift, and (b) for redelivery at a safe (named) port, which
will best suit the owners having regard to the subsequent employ-
ment in view.
The preamble clause of some time charter parties is so phrased
and constructed as to constitute a warranty as regards (a) dead-
weight and measurement capacity, (b) speed, and (c) consumption.
To obviate disputes, the general procedure is to state "the total
deadweight about tons on Lloyd's summer freeboard, inclusive
of bunkers, stores, fresh water and equipment, and having about
cu. ft. grain, and cu. ft. bale space (exclusive of
permanent bunkers which contain about tons) all as per
builder's plan and capable of steaming about knots per hour
under favorable weather conditions on a consumption of about
— tons of best Welsh coal per day of 24 hours."
Generally speaking the lower forepeak is reserved for the ship's
stores, and part of the poop space may be encroached upon for
storerooms or for crew or other purposes, and it is advisable to
make that clear as the full measurement of these spaces are as a rule
included in the builder's plan.
Hire is based on the total deadweight capacity of the vessel.
2. Delivery; Commencement of Hire. — Hire generally commences
from the hour and date of the vessel being placed at the time char-
terer's disposal at such safe and suitable dock, wharf, or place
immediately available, and written notice given within office hours.
But some time charterers stipulate for hire not to commence for
24 hours (Sundays and holidays excepted) after written notice has
been given, and even make full use of the vessel for loading purposes
from the hour she is presented. Such a stipulation, being unfair
and one-sided, should be eliminated, or in a case where that cannot
* From Shipping Illustrated, New York.
Digitized by LiOOQ LC
708 SHIP OPERATING
be accomplished the words "unless used" should be inserted so that
owners will be paid from the actual time at which loading com-
menced or use was made of the vessel before the expiration of the
24 hours.
3. Redelivery Clause. — Similarly the redelivery of the vessel
should only be accepted between office hours and not during the night
nor on Sunday or legal holiday, and that should be stipulated
for in all time charter parties. It is the practice, where no pro-
vision is made, for the time charterer to redeliver the vessel at
whatever time the discharge of cargo is completed or, in the case
of a vessel in ballast, at the hour of her arrival at redelivery port.
Owners are entitled to get redelivery of their vessel, in the same
good order (ordinary wear and tear excepted), with all holds swept
clean, as she was when delivered.
4. In the preamble clause in certain time charters, "Vessel
being in every way fitted for service," should be altered to read as
"presently" fitted for ordinary cargo service, so that the liabilities
and obligations of the owners and time charterer may be clearly
denned and questions obviated.
5. Trading Limits and Insurance Warranties. — When, for a
period of time, a time charter is entered into for employment of
the vessel in lawful trades between good and safe ports or places,
and the time charterer desires the widest limits, it is the rule to
affix Owners1 Insurance Warranties and Trade Restrictions, within
which limits the vessel may be traded. But sometimes it arises
during the currency of the charter that the time charterer may
wish to employ the vessel outside these limits, in which case a
mutual arrangement may be entered into.
Where an insurance warranty is absolute, as in the case of "No
White Sea," for example, it is necessary for owners first to ascer-
tain that such warranty will be cancelled for an additional premium,
and to consider the extra risks to their vessel thereby involved,
and to arrange a fixed additional payment of hire plus the extra
premium to be paid by the time charterer. .
6. Speed and Consumption. — A steamer's speed is dependent
upon weather conditions and the steam-producing quality of the
coal supplied by the time charterers. Allowance must be made
for adverse weather conditions as a steamer cannot cover the ground
and make the distance when the elements are battling against her.
Section 4286 of the United States laws governing Steamboat
Inspection Service states: "The charterer of any vessel, in case
Digitized by VjOOQ 1C
BERTH TERMS • 700
he shall man, victual and navigate such vessel at his own expense,
or by his own procurement, shall be deemed the owner of such
vessel within the meaning of the provisions of this title relating
to the limitation of the liability of the owners of vessels; and such
vessel, when so chartered, shall be liable in the same manner as if
navigated by the owner thereof."
In grain freights the quotations are per quarter. The "net"
freight is per ton of 20 cwt. on the quantity of heavy grain carried,
or on the guaranteed deadweight of the steamer. The net register
basis provides for the payment on the net register tonnage of the
vessel.
Berth terms means that the steamer is to be loaded as fast as
she can take in as customary at port of loading, and to be discharged
as fast as she can deliver at port of discharge.
In grain freights, either on "berth terms" or on the C.f.o. basis,
the quotations, unless otherwise stipulated, are for heavy grain
of 480 lb. per qr., and if for oats 320 lb. per qr. From the Gulf
ports tonnage is mostly fixed for grain on what is called the net
form of open charter, which implies that all expenses at loading
and discharging of the cargo are paid by charterers, so that the
owners pay the working expenses of the boat, and what commis-
sion may be agreed upon.
Cotton rates are either quoted in so many cents per 100 lb. or in
fractions of an English penny per lb. or on the net register basis.
"F.t." refers to ore charters, and means "full terms," that is,
with despatch-money both ends.
Prompt means that the steamer is within a week or so of the
loading port.
Spot signifies that the vessel is at the port of loading.
Gulf ports means the Gulf of Mexico, Port Arthur or Galveston
to Tampa inclusive.
Dreading means option of shipping general cargo, charterers
paying all extra expenses over and above a cargo of grain at loading
port, and freight, to be equivalent to what it would be with a full
" cargo of grain. This clause is sometimes stipulated to apply also
to port of discharge, such as Dreading at both ends.
Form D is an American charter for cotton, etc. (freight paid on
d.w., and steamer receiving lump sum for each day's loading).
Form O means that the freight is paid on the net register, and
in consideration of owners paying charterers so much per net register
24
r
710 , SHIP OPERATING
ton, mostly 2s. per ton, they pay stevedoring, compressing and port
charges at loading port or ports.
Anglo form is a Chamber of Shipping charter on net register
basis, which is generally considered to afford more protection in
its conditions to owners, Form O being full of clauses more favorable
to charterers.
C.f.o. means Cork (or Channel) for orders. For instance, C.f.o.
3s. 3d. means that if the boat is ordered to proceed to Cork for
orders to discharge at a port in the United Kingdom or Continent,
she gets 3s. 3d. if ordered from there to a U. K. port and 10% addi-
tional if to a Continental port; but if ordered direct from a loading
port to the U. K. there is 3d. reduction, and if to the Continent,
no reduction (3s. 3d.).
Northern range refers to the Atlantic ports, as follows: Portland,
Boston, New York, Philadelphia, Baltimore, Newport News,
Norfolk.
Boat loads, 8,000 bushels grain in canal boat.
D.l.o. — Dispatch loading only.
D.p. — Direct port.
D.w. — Deadweight.
E.C. Ireland — East Coast Ireland.
F.a.s. — Free alongside ship.
F.f.b. — Free of freight brokerage.
F.o.w. — First open water.
L.H.A.R. — London, Hull, Antwerp or Rotterdam.
No red B/Ch. — No reduction Bristol Channel.
O/C .— Open Charter.
O.T. — On track or railway.
"Pixpinus" (timber charters) is the official form agreed upon
by owners and merchants for wood cargoes.
P.t. — Private terms.
Sun./ext. — Sundays excepted in lay days.
U.K.f.o. — United Kingdom for orders. •
U.K.H.A.D. — United Kingdom, Havre, Antwerp or Dunkirk.
W.B.— West Britain.
W.C. England.— West Coast England.
MARINE INSURANCE
A contract of marine insurance is a contract of indemnity whereby
the insurer undertakes to indemnify the insured, in the manner
and to the extent agreed, against marine losses, that is, the losses
i by Google
INSURABLE VALUE 711
incident to marine adventure. Unless specially mentioned in the
policy, goods are not insured until they are on board the vessel
which is to carry them. The following section contains abstracts
from Sea Insurance by W, Gow.
Insurable Value. — Where no special contract is made between
the insured and the underwriter the insurable value of certain mat-
ters of insurance is fixed by law as follows:
(1) Ship. — Her value at the commencement of the risk including
outfit, provisions, stores, advances of wages, and any other outlays
expended to make the ship fit for voyage or the period of navigation
covered, plus the cost of insurance upon the whole.
The insurable value in the case of a steamship includes the ma-
chinery, boilers, coal, and engine stores if owned by the insured,
and in the case of a ship engaged in a special trade, the ordinary
fittings for that trade. Note that the policy on hull and machinery
does not cover coal and stores.
(2) Freight. — Whether paid in advance or otherwise, the in-
surable value in the gross amount of the freight at the risk of the
insured, plus the charges of insurance.
(3) Goods or Merchandise. — The insurable value is the prime .
cost plus expenses of and incidental to shipping and cost of in-
surance.
Terms
The term ship includes the hull, materials, and outfit, stores,,
and provisions for the officers and crew, and in the case of vessels
engaged in a special trade, the ordinary fittings requisite for the
trade, and also, in the case of a steamship, the machinery, boilers,
coal, and engine stores if owned by the insured.
Freight includes the profit derivable by a shipowner from the
employment of his ship to carry his own goods, as well as freight
payable by a third party, but does not include passage money.
Goods includes goods in the nature of merchandise, and does
not include personal effects or, provisions and stores for use on
board. In the absence of any usage to the contrary, deck cargo
and living animals must be insured specifically and not under the
general heading goods.
Policies. — The intending insured (principal or broker) offers
the risk by showing to the underwriter a brief description of the
venture, called in Great Britain a "slip" and in America an "appli-
cation.11 The underwriter signifies his acceptance of the whole or
ioogle
712 SHIP OPERATING
of a part of the value exposed to perils of the sea by signing the
slip, and putting down the amount for which he accepts liability.
From this slip is worked up the complete contract or policy.
The following five paragraphs must be specified in a marine policy:
1. The name of the insured or of some person effecting the in-
surance on his behalf.
2. The risk covered, that is, both the subject matter insured and
the perils insured against.
3. The voyage covered or, in case of time insurance, the period
of time during which the protection of the policy is to last, or if
it is intended to cover not only a voyage but also a period of time,
or a period of time succeeded by a voyage, then both must be
distinctly specified.
4. The sum or sums insured,
5. The name or names of the underwriters.
Unless the policy otherwise provides, the insurer on ship or
cargo is not liable for
Any loss proximately covered by delay, although the delay may
be caused by a peril insured against;
Ordinary wear and tear;
Ordinary leakage and breakage;
Inherent vice or nature of the subject matter insured, i. e., as
fruit rotting, meat becoming putrid, or flour heating not from
external damage but solely from internal combustion.
- The term "thieves" does not cover clandestine theft or a theft
committed by one of the ship's company, whether crew or passen-
gers.
Where goods are insured until they are safely landed, they must
be landed in the customary manner, and within a reasonable time
after arrival at the port of discharge, and if they are not so landed
the risk ceases.
"Perils of the sea" refers only to fortuitous accidents or casualties
of the sea. The damage caused by springing a leak is not a charge
on the underwriters unless it be directly traceable to some for-
tuitous occurrence.
Where the leak arises from the unseaworthy state of the ship
when she sailed, or from wear and tear or natural decay, and is
only in consequence of that ordinary amount of straining to which
she would unavoidably be exposed in the general and average course
of the voyage insured, the underwriter is not liable.
A clause is often inserted in a policy admitting the seaworthiness
Digitized by VjOOQ IC
VOYAGE POLICY 713
of the vessel for the purpose of the insurance. Where this is at-
tached to a policy, it is a concession on the part of the underwriter
that any leak arising must be from a peril of the sea.
The term "All other perils" includes only perils similar in kind
to those insured against.
All risks of war are eliminated from the marine coverage, but
this may be had separately with or without marine coverage. A
marine coverage may be secured to protect any insurable hazard,
but it is decidedly in order for the insurer to realize what risks he
retains and what risks are covered by his contract.
There are different kinds of policies as:
Voyage Policy, in which the subject matter is insured at and
from, or merely from one place to another place or places.
Time Policy, where the subject matter is insured for a period
of time definitely specified.
Valued Policy, one which specifies the agreed value of the sub-
ject matter insured.
Unvalued Policy, one which is open to the insured to insure
for a definite sum his interest in the subject matter of the policy
without stating any value attributed by him to the subject matter.
Floating Policy describes the insurance in general terms and
leaves the ship or ships and other particulars to be defined by
subsequent declaration.
Clauses and Terms Occurring in Policies
General Average (G. A.)* — Suppose a vessel springs a leak, and
to save her from sinking the captain throws overboard a portion of
her cargo. The last shipment loaded is generally the first to come
out.
If the shipment is fully insured the underwriters will pay the
amount assessed against the goods, but whether the goods are
insured or not the general average will make good to the owner the
value of the goods which were jettisoned less the assessment which
the owner is called upon to pay. It is safe to figure that all policies
of insurance on goods cover and protect the merchant against
assessments in general average.
A sacrifice to protect the ship alone or the cargo alone is not
covered by general average. It is the opposite of an accidental loss
caused by a maritime peril. A loss caused by water to extinguish
a fire is general average, but not to the packages which themselves
were on fire.
Digitized by LjOOQ LC
714 SHIP OPERATING
Particular Average (P. A.) — A particular average loss is a par-
tial loss of the subject matter insured, caused by a peril insured
against, and which is not a general average loss. Particular average,
instead of being contributed for the general body of those who
are interested in the adventure, falls entirely upon the owner of
the property deteriorated by the damage.
Particular Charges. — Expenses incurred by or on behalf of the
insured for the safety or preservation of the subject matter insured,
other than general average and salvage charges, are called par-
ticular charges. Particular charges are not included in general
average or particular average. They are covered in the policy by
permission granted to sue, labor and travel in and about the defense,
safeguard and recovery of the goods.
Free of Particular Average (F. P. A.). — Warranted free from
average unless general, or the ship is stranded, sunk, burned, or in
collision.
If the vessel is stranded the insurer has to pay particular average
without regard to percentage and whether or not the damage is
in any way attributable to the stranding. The damage to the
goods may have occurred prior to the stranding or after the strand-
ing, and from an entirely different cause, but providing they were
on board at the time of stranding and the insurance was then in
force, the damage is recoverable from the underwriters.
The same applies to "burnt, sunk, or in collision," but a vessel
which might be on fire is not necessarily .interpreted as burnt, nor
is a fire confined to cargo covered, and the term "or in collision"
is interpreted by the courts as if it read with another vessel, unless
otherwise modified in the contract.
Per cent Particular Average Clause. — "Subject to Particular
Average if amounting to per cent." The object of this
limitation in amount is to prevent an endless amount of small claims
which would involve expense of adjustment without due return.
It is often modified to divide a single shipment into several units
and becomes applicable to each.
With Average (W. A.) means that no claim will be made on the
underwriters for partial loss caused by sea perils unless the damage
amounts to 5% or more of the value of the shipment.
F. A. A. is an abbreviation of the clause "Free of all average."
Foreign General Average (F. G. A.) is a clause stating that
general average and salvage charges are payable as per official
Digitized by VjOOQ IC
RIVER PLATE CLAUSE 715
foreign statement if so made up, or per York-Antwerp rules if in
accordance with the contract of affreightment.
River Plate Clause. — The risk under this policy shall cease upon
arrival at any shed (transit or otherwise), store, custom house,
or warehouse, or upon the expiration of 10 days subsequent to land-
ing, whichever may first occur.
This clause is being quite generally insisted on by the com-
panies, particularly on policies to Brazil, Buenos Aires, and the
River Plate, as, owing to the large number and size of shore losses, the
marine insurance companies do not care to assume the risk. To
give more complete protection to shipper or to banks advancing
money under credits, any marine policy bearing this clause should
be accompanied by a fire floating policy covering from piers, in
transit, and in custom houses for at least a minimum period.
Protection and Indemnity Clause (P. and I.) gives the insured
additional protection against loss. It contains several paragraphs
among which are the following:
"Loss or damage in respect of any other ship or boat or in respect
of any goods, merchandise, freight or other things or interest what-
soever on board such other ship or boat caused proximately or
otherwise by the ship insured in so far as the same is not covered
by the running down clause hereto attached.
"Loss or damage to any goods, merchandise, freight or other
things or interest whatsoever other than as aforesaid whether on
board the said steamship or not, which may arise from any cause
whatever."
The P. and I. clause adds about one-half of one per cent, to the
ordinary rate.
Collision or Ruling or Running Down Clause (R. D. C.) is a
clause in which the underwriters take a burden of a proportion,
usually three-quarters of the damage inflicted on other vessels by
collision for which the insured vessel is held to blame. Sometimes
this clause is extended to cover the whole of the insured's liabilities
arising out of the damage due to property by the collision of the
insured vessel with another, and the clause is then known as the
Four-Fourths Running Down Clause.
F. C. and S. Clause. — Free of capture and seizure.
Inchmaree Clause. — This covers loss of or damage to hull and
machinery through the negligence of master, mariners, engineers,
and pilots, or through explosions, bursting of boilers, breakage of
shafts, or through any latent defect in the machinery or hull, pro-
Digitized by VjiOOQIC
716 SHIP OPERATING
vided such loss or damage has not resulted from want of due dili-
gence by the owner or owners of the vessel or by the manager.
Rates. — The rate of insurance depends on the age and condition
of the vessel, and if classed under Lloyd's, Bureau Veritas, and
American Bureau of Shipping Rules. New vessels generally are
given low rates, as 1%, while old 5% or over.
EXPORT AND SHIPPING TERMS
Bill of Lading (B. L.) is a receipt for goods delivered to a carrier
for transportation. The bills of lading of some steamship com-
panies contain the following clause: "Freight is to be considered
earned at time of receipt of shipment and is to be paid whether
vessel or goods are lost or not." This clause in a bill of lading
has been held to be valid by the courts. In accepting a bill of lading
containing this clause the shipper guarantees to pay the freight
charges whether the vessel or goods are lost or not, and consequently
should add the amount of the freight to the value of the goods
when making declaration to the underwriters. In foreign trade,
bills of lading are generally made out in triplicate, one for the
shipper, one for the consignee, and one retained by the master.
Manifest — A document signed by the master of a vessel con-
taining a list of the goods and merchandise on board, with their
destination, for the use of the custom house officials. By U. S.
Revised Statutes 2807, it is required to contain the name of the ports
of lading and destination, a description of the vessel and her port,
owners and master, names of consignees and of passengers, and
lists of the passenger's baggage and of the sea stores.
Bottomry. — The borrowing of money and pledging the ship as
security for repayment.
Respondenta. — A loan made on the goods shipped.
Salvage is the reward granted by law for saving life and property
at sea.
C. F. or C. A. F. (Cost and Freight) means that the seller fur-
nishes the goods and pays the freight — no other expenses — to the
port of destination. All risks while the goods are in transit are
for the account of the buyer.
C. I. F. (Cost, Insurance and Freight). Here the seller fur-
nishes the goods and pays the freight and insurance to port of
destination, all other risks while goods are in transit being for the
account of the buyer.
F. O.B. Steamer (Free on Board). The seller is to deliver the goods
Digitized by VJiOOQ 1C
F. A. S. STEAMER 717
aboard the steamer at the port of shipment in proper shipping condi-
tion; all subsequent risks and expenses are for account of the buyer.
F. A. S. Steamer (Free at SiJ^^feans thq,t the seller is to deliver
the goods alongside steamer en lighter in the port of shipment or on
receiving pier of the steamship company in proper shipping condition;
all subsequent risks and expenses are for account of the buyer.
F. F. A. (Free fronp'^AJongside), the shipper pays lighterage
charges in the port of destination from the steamer. All further
charges are for the account of the consignee.
F. O. (Free over Side). Without charges up to and including
the unloading of a vessel.
Demurrage. — A charge for delay in loading or unloading a vessel.
With Exchange, on a draft, means that the cost of collection is
to be added to the amount of the draft and paid by the party on
whom it is drawn.
A vessel is said to be Documented, when a paper giving full
particulars of her and the names of her owners is filed at the Cus-
tom House of the city which is her home port.
Barratry. — A wrongful act willfully committed by the master
or crew to the injury of the owner or to the charterer of the vessel.
Jettison. — The throwing overboard of a part of the cargo or any
article on board a ship, for the purpose of lightening her in case
of necessity.
Drawback. — A drawback or refund of duties is when an imported
material is used in the manufacture of domestic goods which is
exported, the U. S. Government allowing the exporter the import
duty paid, less one per cent.
Lay Days are the days agreed on by the shipper and master or
agent for loading and discharging cargo and beyond which a de-
murrage will be paid to the vessel. Sundays and legal holidays
do not count unless the term "running days" is inserted, in which
case all days are included.
Clearance Papers. — When ready for sea the custom officials
must be provided with a detailed manifest of the ship's cargo. If .
the port charges have been paid and her cargo is properly accounted
for, then the collector of the port will furnish the master with
clearance papers, without which the vessel must not leave port.
Bill of Health is a certificate stating that the vessel comes from
a port where no contagious disease prevails, and that none of the
passengers (if carried) or the crew at the time of departure was
infected with any disease.
Digitized by LiOOQ IC
718 SHIP OPERATING
AUTHORITIES QUOTED
The following list contains books from which abstracts were
taken. The writer has endeavored to include all, but should any
have been inadvertently omitted, they will be included in future
editions of the present handbook.
Ship Calculations and Construction. G. Nicol.
Class book on Naval Architecture. W. J. Lovett.
Text book on Naval Architecture. J. J. Welch.
Theoretical Naval Architecture. L. L. Attwood.
Modern Seamanship. A. M. Knight.
Naval Construction. R. H. M. Robinson.
Speed and Power of Ships. D. W. Taylor.
Naval Architecture. C. H. Peabody.
v Design and Construction of Ships. J. H. Biles.
V Practical Shipbuilding. A. C. Holmes.
Naval Constructor. G. Simpson.
v Steel Ships. T. Walton.
Douglas Fir Shipbuilding. U. S. Forestry Service.
Fighting Ships. Jane.
Lloyd's Rules.
Am. Bureau of Shipping Rules.
Naval Reciprocating Engines. J. K. Barton and H. O. Stickney.
Practical Marine Engineering.
Design of Marine Engines and Auxiliaries. E. M. Bragg.
Manual of Marine Engineering. A. E. Seaton.
Marine Steam Engines. R. Sennett and H. J. Oram.
Verbal Notes. J. W. M. Sothern.
Marine Steam Turbines. J. W. M. Sothern.
Engine Room Practice. J. G. Liversidge.
Marine Engineering. A. E. Tompkins.
McAndrew's Floating School. C. A. McAllister.
Design of Marine Boilers. J. Gray.
Care of Naval Machinery. H. C. Dinger.
Marine Boiler Management. C. E. Strohmeyer.
Marine Steam. Babcock & Wilcox Co.
Oil Fuel. Texas Co.
Machinery's Handbook.
Mechanical Engineer's Pocket Book. W. Kent.
Am. Electrical Engineer's Handbook.
Am. Civil Engineer's Handbook.
International Correspondence School Handbooks, Scranton, Pa.
v Pocket Companion. Carnegie Steel Co.
Cambria Steel Handbook.
Naval Electrician's Handbook. W. H. G. Bullard.
Cold Storage, Heating and Ventilating. S. F. Walker.
Sanitary Refrigeration and Ice Making. J. J. Cosgrove.
Heating and Ventilating. B. F. Sturtevant Co.
Mechanical Draft. Am. Blower Co.
Marine Propellers. S. W. Barnaby.
Digitized by LiOOQ LC
AUTHORITIES QUOTED 719
Screw Propellers. C. W. Dyson.
Naval Ordnance — a handbook used at U. S. Naval Academy.
Animal and Vegetable Fixed Oils and Greases. C. R. A. Wright.
Ship Wiring and Fitting. T. N. Johnson.
Standard Wiring. H. C. Cushing, Jr.
Sea Insurance. W. Gow.
VModern Seamanship. R. M. Knight.
Ship Forms, Resistance and Screw Propulsion. G. S. Baker.
* Manual of Seamanship, published by the British Admiralty.
Handbook of the Lukens Iron & Steel Co.
Motor Boats. American Technical Society, Chicago.
Art of Estimating the Cost of Work. W. B. Ferguson.
In the handbook are quotations of articles published in Inter-
national Marine Engineering, New York; Shipping Illustrated, New
York; Marine Review, Cleveland, O.; Pacific Motor Boat, Seattle,
Wash!; and Shipbuilder, London. Also from papers from Transac-
tions of American Society of Naval Architects, Society of Naval
Engineers and from the International Engineering Congress held in
San Francisco in 1915.
Abstracts were made from catalogues issued by the following
companies:
Ashton Valve Co., Boston, Mass.
American Steam Gauge Co., New York.
American Engineering Co., Philadelphia, Pa.
C. H. Wheeler Manufacturing Co., Philadelphia, Pa.
Worthington Pump & Engineering Co., New York.
M. T. Davidson Co., New York.
Hyde Windlass Co., Bath, Me.
Dean Bros. Steam Pump Co., Indianapolis, Ind.
Crane Co., Chicago, 111.
H. G. Roelker (Allan dense air machine), New York.
Schutte & Koerting, Philadelphia, Pa.
General Electric Co., Schenectady, N. Y.
Carlisle & Finch Co., Cincinnati, O.
National Tube Co., Pittsburgh. Pa.
Griscom-Russell Co., New York.
Durable Wire Rope Co., Boston, Mass. \
J. A. Roebling Sons Co., Trenton, N. J.
G. C. Moon Co., New York.
Baldt Anchor Co., Chester, Pa.
Power Specialty Co., New York.
J. H. Williams Co., Brooklyn, N. Y.
Ross Schofield Co., New York.
Dake Engine Co., Grand Haven, Mich.
Welin Marine Equipment Co., Brootyyn, N. Y.
Westinghouse Electric Manufacturing Co., Pittsburgh, Pa.
Eckliff Boiler Circulator Co.,*Detroit, Mich.
New London Ship & Engine Co., Groton, Conn.
Digitized by LiOOQ LC
r
720 SHIP OPERATING
Werkspoor-Diesel Engine Co., New York.
J. L. Mott Co., New York.
Ashwell & Nesbit, Ltd., Leicester, Eng.
Am. Radiator Co., New York.
C. W. Hunt Co., New York.
Brunswick Refrigerating Co., New Brunswick, N. J.
Bolinders Co.j New York.
Penberthy Injector Co., Detroit, Mich
A. B. Sands Co., New York.
White Engineering Co., New York.
Holtzer-Cabot Electric Co., Boston, Mass.
Edison Storage Batteiy Co., Orange, N. J.
Digiti
zed by GO0gk
INDEX
Absolute pressure, 440
Absolute aero, 344
Admiralty bronxe, 156
Air, cooling by, 505
escape of, 583
for combustion, 353, 300
velocity of, escaping into the atmos-
phere, 300
Air change, duct area for, 584
Air ducts, 582
Air pipes to inner bottom, 263
Air pressure, 380, 421
measuring, 576
Air pressure — water pressure, 577
Air pump. 418, 458
types of, 450
Air pumps, sizes of, 452, 460
Alloys, copper, sine, tin, 157
Aluminum, 155
American Bureau of Shipping, 235
Ammeter, 543
Ammonia, 501, 504, 507, 601
piping for, 527, 506
Ammonia compressors, 507
Ammunition, 245
Ampere, 531
Anchor cranes, 661
Anchors, lifting speed, 625
tables of, 657
types of, 657
Angle valves, 528
Angles, sixes and weights of, 131, 133,
130
Anthracite coal, sizes of, 351
Apothecaries' weight, 1
Ardois signals, 566
Areas of plane figures, 33
Armament, 245
Armor, 244
Armor backing, 244
Armored crujsers, 248
Asbestos, 163
Ash ejectors, 384
Atmospheric pressure, 344, 448
Authorities, 718
Auxiliaries, steam plant, 448
Auxiliary drain, 602
Avoirdupois weight, 1
Awning deck vessels, 230
freeboard of, 206, 211
Back pressure, steam engine, 306, 456
Baltime charter, 705
Band edge flats, sixes of, 130
Barge, 673
Barges, wood, 282, 284
Barrels, sixes of, 20, 355
Bath tubs, 606
Battens, cargo, 285, 288
Batteries, electric, 554
Battery cells, grouping of, 557
Battle cruisers, 248
Battleships, 247
Beam, bending moment of, 76
moment of resistance of, 76
neutral axis of, 76
reaction of, 76
shearing stresses in, 77
strength calculation for, 76, 78
Beams, deck, 265 '
deck, round of, 213, 265
deck, of wood vessels, 282
deflection of, 78, 84
I, H and bulb, 136, 138
loading of, 78
Bearing surfaces, steam engine, 414
Bearing, thrust, 418
Bearings, line shaft, 418
Beaume gravity of oils, 354, 35$
Bell wires, 546
Bending moments, curve of, 205, 200
Bending pipes and tubes, 510
Berths, 287
Bessemer steel, 111
Bilge ejector, 603
Bilge keels, 264
721
r
722
INDEX
Bilge pumps, 603, 477
Bitt or bollard, rises of, 9£
Bitumastic enamel, 280
Bituminous coal, sizes of, 352
Block coefficient, 172
Block sheaves, number of, 654
Blocks, steel, 648
types of, 645, 647
wood, 648
working load for, 648
Blowers, 391, 580
Blow-off valves, 530, 378
Board measure, 8
in timber, 9
Board of Trade, 237
Boat davits, 673, 665
formulae for, 98
Boat spikes, 293
Boiler, boiling out, 387
cleaning tubes of, 387
grate area of, 363, 364, 421
heating surface, 363, 364, 421
leg, 366
locomotive, 366
operating of, 385
overhauling, 386
return tube, 366
Scotch, heat distribution in, 375
shutting off, 386
washing out, 387
Boiler accessories, 376
Boiler circulators, 379
Boiler covering, 163
weight of, 307
Boiler efficiency, 374
Boiler feed pumps, 473, 475
Boiler feed water connections, 377
Boiler feeding, 478
Boiler firing, 385
Boiler fittings, 376
Boiler horse power, 371
Boiler horse power for an engine, 371
Boiler plates, 72
Boiler pressure, 364, 370, 421
Boiler rivet steel, 110, 72
Boiler room, draining of, 604
floor plates of, 125
length of, 305, 310
painting in, 281
ventilators to, 579
Boiler saddles, 277
Boiler scale, removing of, 388
Boiler tubes, tables of, 510, 511, 512
Boiler weights, 306, 308, 370
Boiler sine stripe, 701
Boilers, boiling out, 387
cleaning of, 387
cleaning tubes of, 387
life of, 701
oil for, 356
prices of, 337
types of, 363
water evaporated in, 371, 375
water tube, 369
weights of, 308, 370
Bolts, carriage, 132
in deck planking, 28
eye, tests of, 95
shearing and tensile strength of, 93
stove, 132
Bolts and nuts, 524
Boot top, 279
Bottom blow valve, 378
Bourdon tube, 378
Bower anchor, 659
Brake horse power, 22
Brakes, solenoid, 566
Brass, naval, 157
Brass pipe, 518
Brass sheets and plates, weights of,
126, 127
Brass tubes, 511, 514
working pressure formula, 518
Brass wood screws, 291
Brasses, 156, 71
Breadth, extreme, 166
molded, 166
Brine circulating system, 593
British Corporation, 236
British thermal unit, 341, 23
Bronses, 156
Bulb angles, rises and weights of, 139
Bulb beams, sizes and weights of, 138
Bulkheads, cabin and stateroom, 285
caulking of, 272, 321
fore and aft, 268, 299, 320
heat through, 567
painting of, 281
transverse, 268, 320
Bulwarks, 261
Bumpkin, 276
I Bundling schedule for pipe, 20
Digitized by >
ile
INDEX
723
Buoyancy, center of, 172
Buoyancy curve, 295, 296
Bureau Veritas, 237
Bursting pressures of wrought iron
tubes, 91
Butterfly valves, 529
Butt straps, riveting of, 106
Butt-welded pipe, 507
Butts, shell plating, 260
Cabin bulkheads, 285
Calorie, 341
Calorifiers, 610
Camber, beam, 213, 265
launching ways, 228, 232, 233
Capstan, purchase on rope from, 63C
Oapstans, 630
Carbonic anhydride, 594, 601
piping for, 596
Carbon steel, 112, 114
Carburetors, 482
Cargo battens, 285
Cargo steamers, data on, 310, 311
Cargoes, coal, 693
contracts for moving, 704
grain, 688
loading and stowing of, 683
lumber, 694
oil, 684
Carpenter work, 284
Carriage bolts, 132
Cast iron, 120, 71
columns, 85, 87
Cast steel, 118, 116, 72
wire rope, 639, 641
Cattle steamer, cost of fitting up,
331
Cattle steamers, fittings for, 330
Caulking, deck planking, 285
Caulking bulkheads, 272, 321
Caulking cotton, 162
Cavitation, 425
Ceiling, 285, 288
Cement, Portland, 162
Cement coating, 265, 278, 698, 699
See also Concrete
Center of buoyancy, 172
distance from metacenter, 176
fore and aft, 173, 178
height of, 179
from water line, 173
Center of gravity, 50
of a ship, 200
effect of moving weights on, 203
heights of, 202
to find by moving weights, 204
of a ship's cross section,
50
of a water plane, 51
Centigrade thermometer, 25
Centimeter, gram, second system, 6
Centrifugal pumps, data on, 474,
475
priming of, 476
speed of, 476
types of, 474
Chain, steering, 624
strength of, 91, 655
table of, 656
Chain stoppers, 624
Chairs, 287
Channels, shipbuilding, 129
Charcoal iron boiler tubes, 512
Charter forms, 704
Chartering, ship, 703
Check valves, 529, 378, 471
Checkered steel plates, 125
Chemical analysis of coal, 351
Chill or cold test of oil, 356 •
Chromium nickel steel, 114
Chromium steel, 114
Chromium vanadium steel, 114
Circle, properties of, 32
Circles, tables of, 25, 29
Circuit breaker, 543
Circular measure, 3
Circular mil, 533
Circular ring, measures of, 36, 37 «
Circulating pumps, speed of, 462
sues of, 452
Circulators, boiler, 379
Classification societies, 234
Clinker plating, 259
Closets, 607
Coal, heat values of, 351
required to evaporate one lb. of
water, 349
sizes, of anthracite, 351
of bituminous or soft, 352
value of, from its chemical analysis,
351
Coal cargoes, 693
Digitized
by Google
724
INDEX
Coal consumption, 363, 421
per i.h.p., 349, 350, 411, 443
See also Trials
Coal consumption and cylinder cut-off,
405
Coamings, height of, 267
side, 266
Cocks, 528
Coefficient, block, 172
of elasticity, 70
of fineness for freeboard calculations,
210
of fineness of water plane, 171
of midship section, 172
prismatic, 171
propulsive, 223
Cofferdams, 320, 321
Cold storage room, refrigeration for, 598
Cold storage temperatures, 588
Collapsing pressures of wrought iron
tubes, 91
Color of oil, 356
Columns, 84
cast iron, formulas for, 85, 87
H and I sections, safe loads for, 86
steel, formulas for, 84, 85
wood, formulae for, 85, 87
. safe loads for, 87, 88
wrought iron, safe loads for, 88, 89
Combustible, evaporation per lb. of, 350
Combustion, air for, 353
rate of, 350
Combustion chamber, 363, 364
Combustion chamber temperature, 393
Companionways, 286, 287
Comparison, law of, 226
Compartment flooded, to find trim, 194
Compound wound motors, 561
Compression, 70
materials in, 71
system for refrigeration, 591
Concrete, 73, 162, 278
See also Cement
Condensers, injection water for, 457
jet, 450, 456
keel or outboard, 459
pressures in, 456
steam temperatures in, 456
surface, 450
data on, 452, 421
operating, 453
Condensers, surface, velocity of injec-
tion water, 462
thermodynamics of, 449
types of, 450
vacuum in, 455, 456
Conduits, electric, 541
Cone, measures of, 36
Connecting rod, formula for, 413
Construction, systems of ship, 253
Controllers, electric, 565, 628
Cooling coils, pipe for, 596
Copper, 155, 71
Copper pipe, 518
Copper sheets and plates, weights of,
126, 127
Copper tubes, tables of, 511, 513, 514,
519
working pressure formula, *5 18
Cork, insulating, 163, 587
Cork paint, 289
Corrosion, to prevent, 698
Cosecant, of an angle, 40
Cosecants, table of, 43
Cosine of an angle, 40
Cosines, table of, 43
Cost of fitting up a cattle steamer,
331
Cost of operating. ' See Operating cost
Cost, parts of a motor boat, 337
Costs, labor, 340
of electric installations, 337
of propelling machinery, 339
of steam engines, 377
of refrigerating systems, 337
Cotangent of an angle, 40
Cotangents, table of, 43
Cotton, caulking, 162
Cotton seed, cargo of, 691
Coulomb, definition of, 531
Couplings, pipe, 526
Covering, pipe, 163, 165
tank top, 263
Coverings, deck, 264
Cranes, anchor, 661
stresses in, 98
Crank sequences, 396
Crew's quarters, painting in, 288
Cross bunker, volume of, 38
Cross curves of stability, 185
Cross section, ship's, center of gravity
of, 50
Digitized
by Google
INDEX
725
Crucible steel, 111
Crude petroleum, 353
Cruisers, battle, 248
light, 248
Cube root, 27, 29
Cubes, of numbers, 29
Cubic capacity, 170
Cubic feet per ton of materials, 16
Curve, of bending moments, 295, 299
of buoyancy, 295, 296
of deadweight, 168
of displacement, 169
of loads, 295, 296
of shearing stresses, 295, 298
of tons per inch, 171
of weights, 294, 295
Curves, of stability, 183
Cut-off, steam engine, 395, 405
Cut-outs, electric, 546
Cutters, 673
Cylinder, covering of, 164
drains and relief valves, 415
measures of, 36
Cylinders, bursting formula for, 90
steam engine, formula for, 413
steam, pressure in, 404, 405
Dangerous articles, carrying, 695
Davits, anchor, sizes of, 660
boat, 673, 665
formulas for, 97
strength calculation for, 77
Deadweight, 169
Deadweight curve, 168
Decimal equivalents of fractions of
inch, 5
Decimals of foot, in inches, 10
Deck beams, 265
round of, 213, 265
Deck coverings, 264
Deck erections, 210, 277 ,
Deck houses, 278
Deck planking, 284, 285
bolts for, 284
Deck plating, 264
Deep framing, 255
Density of oil, 355, 359
Depth, for freeboard, 208
of hold, 167
Lloyd's, 167
Derricks, stresses in, 98
Destroyers, torpedo boat, 249
Details, structural, 253
Diesel engines, 495
compression in, 480
data on, 316
fuel consumption, 495
installations of, 506
operating of, 499
operating cost of, 334, 335, 496
operation of, 496
types of, 501, 316
valves of, 499
weights of, 309
Differential pulley, 652
Dimensions, extreme of a ship, 168, 212,
294
Dinghies, 673
Discharge head, 471
Discharge from nozsles, water, 612
Displacement, of a vessel when out of
trim, 192
of wood vessels, 282
Displacement calculation, 168
Displacement curve, 168
Displacement sheet, 177, 180, 181
Distributing systems, electric, 547
Docking, 699
Docking keels, 264
Doctor, 476
Double bottom, 261
corrosion in, 699
draining of, 604
Draft, 388
air for, 390
closed fireroom, 389
Ellis and Eaves' system, 389
at fan, 421
forced, installations of, 392
heat absorbed in creating, 389
Howden's system, 389
measurement of, 389
resistance of funnel to, 393
velocity of air, 390
See also Trials
Draft figures, 167
Draft of vessel, 167
Drainage systems, 601
Drains, cylinder, 415
Dredges, 327
Drum, rope capacity of, 628
Dry measure, 3
Digiti
zed by G00gk
726
INDEX
Dry steam, 343
Duct area for air change, 684
Ducts, location of, 584
materials used in, 582
Duplex pumps, 474
Eccentric rods, 403
Eddy making, 225
Effective horse power, 223, 225
Efficiency of steam, 342
Ejector, bilge, 603
Ejectors, ash, 384
Elasticity, 70
coefficient of, 70
Electric batteries, 554
Electric capstans, 630
Electric circuits, 547
Electric conduits, 541
Electric distributing systems, 547
Electric fittings, removable, 546
Electric heaters, 573
Electric heating, 573
Electric installations, costs of, 337
data on, 533
laying out, 544
Electric lighting, 541, 544, 547, 550,
552,556
Electric motor circuit, sise of wire,
539
Electric motor controlling devices, 565,
628
Electric motors, 547
calculation of horse power, 562
current required, 564
sues of, 563, 564
types of, 561
Electric output, determination of, 543,
558
Electric propulsion, 444
Electric steering gear, 616, 564
Electric winches, 628, 564
Electric windlasses, 625
Electric wire gauges, 538
Electric wires, carrying capacities of,
534,535
measurement of, 533
running of, 545
sizes of, 537
Electric wiring of gasoline engines,
551
Electric wiring of motor boat, 550
Electric wiring of steamer, 547
Electric wiring, multiple, 557
systems, 539
Electrical and mechanical units, 23
Ellipse, properties of, 33
Ellipsoid, volume of, 38
Enamel, bitumastic, 280
Engelhardt collapsible lifeboats, 671
Engine, boiler horse power for, 371
Engine foundations, 277
Engine revolutions and speed of vessel,
224
Engine room, draining of, 604
length of, 305, 310
painting in, 281
ventilation, 579
Engine room floors, 4J9, 125
Engine room floor plates (i.e. under en-
gine), 256, 263
Engine weights, 305, 306
Engines and boilers, costs of, 339
Engines, Diesel, 495
hot bulb, 492
internal combustion, 478
Estimate for building a motor schooner,
334
Estimated horse power, 411
Estimates, preparing, 338
Evaporation, factor of, 373
per lb. of combustible, 350
Evaporators, sises of, 469
steam for, 468
Excursion steamers* data on, 313, 314,
315
Exhaust relief valves, 530
Exhaust system, 576
Exhausters, 580
Exsecant of an angle, 40
Export terms, 716
Eye bolts, tests of, 95
Factor, of evaporation, 373
of safety, 75, 518, 527
Fahrenheit thermometer, 25
Fan, horse power to drive, 582
Fans, 580
Farad, 531
Feed tank, 462
Feed water check valve, 378
Feed water connections for boiler, 377
Feed water filter, 464
Digitized by >
ioogle
INDEX
727
Feed water beaters, 465
fuel saved by, 467
Field rheostat, 543
Filler, wood, 288
Filter, feed water, 464
Filter tank, 462
Filtering materials, 463
Fire alarms, 614
Fire bars, weights of, 307
Fire bricks, weights of, 307
Fire extinguishing apparatus for oil car-
riers, 325
Fire extinguishing systems, 610
Fire main, steam, 612
water, 610
Fire point of oil, 356
Fire, temperature of, 353
Fire tube and water tube boilers com-
pared, 370
Firing boilers, 385
Fittings for cattle steamers, 330
Flanges, pipe, 522, 528
Flash point of oil, 356
Flat sawing, 157
Flats, sizes of, 139, 140
Floating policy, 713
Floor plates, 256, 263
Floors, engine and boiler room, 419, 125
Flush deck vessel, freeboard of, 205, 210
Flush plating, 259
Food products, keeping of, 587
refrigeration to keep, 599
specific and latent heat of, 600
Foot pound, equivalent units of, 23
Forced draft, 388
Forgings, tests of , 113, 116
Foundations, boilers and engines, 277
capstans, windlasses, etc., 285
Fractions of inch, decimal equivalents
of, 5
Frames, deep, 256
joggled, 256
reverse, 256
of wood vessels, 282
Framing, 255, 265
Freeboard, 205
of awning deck vessel, 206, 211
of flush deck vessel, 205, 210
of hurricane deck vessel, 220
of shelter deck vessel, 216
Freeboard calculations, 210, 213, 218
Freeboard curves, 209, 211
Freeboard markings, 221
Fresh water, 11
Fresh water heaters, 609
Fresh water service, 609
Friction of air in pipes, 585
Friction constants for ships, 227
Frictional resistance of ships, 225
Frustum, of prism or cylinder, 36
of pyramid or cone, 36
Fuel consumption, Diesel engine, 495
Fuel oil, data on, 354, 356
Fuel saved by feed water heaters, 467
Fuels, 349
for internal combustion engines, 478
Fumigating apparatus, 613
Funnel. See Stack
Furnace, temperature of, 393
Furnaces, 364
Fuse, 543, 549
Fusible plugs, 379
Galleys, 673-
Galvanic action, to prevent, 698
Galvanizing steer plates, 121
Gaskets, pipe flange, 526
Gasoline, 358
Gasoline engines, 479, 317
troubles with, 491
wiring of, 551
Gasoline engine generating sets, 559
Gate valves, 529
Gauge, vacuum, 454
Gauge pressure, 449, 344
Gauges, for plates and sheets, 125
standard, 123
steam, 378
for steel and iron plates, 124
water, 379
Geared turbines, 442, 445, 312
operating cost of, 496
Gearing, 148
Generating sets, 557
operating of, 560
Generators, location of, 544, 550
Geometrical propositions, 3L
Gig, 673
Girders, side and center, 263
Globe valves, 527, 528
Grain cargoes, 688
Grapnel anchor, 660
Digitized
by Google
728
INDEX
Grate area, boiler, 363, 364
coal consumption, 421, 363
Great Lakes Register, 237
Ground detector, 543
Grouping battery cells, 557
Gross tonnage, 169
Gunboats, 249
Gun metal, 155
Guy ropes, ships', 645
yacht, 643
Gypsy capstan, 630
Hair felt, 163
Half rounds, sizes of, 137
Hand pumps, 605
Harbor vessels, 313, 314, 315
Hardness of woods, 158
Hard wood sizes, 159
Hatch covers, 285
Hatch openings, 267
Hatchways, 266
Hawsers, Manila, 636, 640, 631
steel, 644, 646, 631
H beams, sizes and weights of, 138
Heat absorbed in creating draft, 389
Heat distribution in Scotch boilers, 375
Heat, latent, of steam, 342
mechanical equivalent of, 341, 23
metric unit of, 341
specific, of superheated steam, 343
through pipe coverings, 165
through ship's side or bulkhead, 567
total of steam, 342
Heat unit, 341, 23
Heat value, coal, from chemical analy-
sis, 351
Heat values, of coal, 351
of oils, 356
of woods, 352
Heaters, feed water, 465
fresh water, 609
Heating, by electricity, 573
by steam, 568
by thermotanks, 571
special systems of, 574
Heating surface, boiler, 363, 364, 421
Heel of vessel lowering boat, 678
Hemp, 634
Hemp clad wire rope, 636, 637
Henry, 531
Hexagons, sizes of, 142
Hitches, 633
Hogging, 298
Hoisting engines, 626
Hoisting rope, data on, 632, 634
tables of, 638, 639
Hold, depth of, 167
Hold pillar, 268, 269
Hole, water that will enter, 195
Hooks, formula for, 91
tests of, 94, 96
Horse power, estimated, 412
equivalent value of, 23
for fan, 582
for generator, 543, 558
for refrigerating machines, 595, 600
motors, calculation of, 562
to raise load, 628
to turn rudder, 623
Horse power formulae, for internal com-
bustion engines, 480
Horse powers, definitions of, 22, 371
Horses, fittings for, 330
Hot bearings, 701
Hot bulb engines, data on, 493, 494, 318
operation of, 492
Hot well, 462
temperature in, 421
Hull construction, 234
Hull maintenance, 696
Hull painting, 279, 288
Hull specification headings, 300
Hull survey, 696
Hull weights, 303, 310
formulas for, 302
of oil carriers, 326
Hurricane deck vessel, 239. 240
freeboard of, 220
Hydrokineter, 379
Hydrometer, 381
I beams, sizes and weights, 136
Ignition, electric, 486
Ignition timing, 489
Immersion, tons per inch, 170
Incandescent lamps, 552
Inch-millimeter table, 5
Inches in decimals of foot, 10
Indicated horse power, 22
calculation of, 410
coal consumption per, 350, 411, 421
for propulsion, 222
Digitized by
Google
INDEX
729
Indicated horse power, steam consump-
, tion per, 342, 421
weight of machinery per, 304
Indicator cards, 406, 701
Induced draft. See Draft
Inertia. See Moment of
Injection water temperature, 421
Injectors, 380
Inner bottom, 261
oil carried in, 321
In and out plating, 259
Inspirators, 380
Installing pumps, 4^7
Insulation of refrigerating rooms, 587
Insulating materials, 162
Insurable value, 711
Insurance, marine, 71d
Internal combustion engines, 478
cooling water for, 484
compression in, 480
electric ignition, 481, 486, 317, 320
fuels for, 478
horse power formula for, 480
oils for, 357
operation of, 479
starting of, 482
valves of, 484
Interior decoration, 285
Interpole motors, 562
Iron, 119
cast, 120, 71
malleable, 121, 71
wrought, 120, 116
Iron plate gauges, 124
Iron rope, 639, 640
Iron wood screws, 290
Isherwood system, 253
Jet condensers, 450, 456
cooling water for, 457
Jiggers, 650
Joggled frames, 256
Joggled plating, 259
Joiner work, 284
Joule, 531, 23
Jump spark ignition, 551
Kedge anchor, 659
Keel blocks, 700
Keel condensers, 459
Keels, 264
bilge, 264
docking, 264
of wood vessels, 282
Keelsons, 263
Keg, number of screws in, 292
Kerosene oil, 478
Keys, 141, 430
Kilogrammeter, 23
Kilowatt, equivalent units of, 532, 23
Kingston valves, 530
Knot, 2
Knots, rope, 633
Labor costs, 340
Lag screws, number in keg, 292
sizes of, 289
tests of, 293
weight of, 292
Lagging, cylinder, 164
Lamps, incandescent, 552
wired in parallel, 540, 550
wired in series, 540
Lap, valve, 400
Lap joint, riveting of, 106
Lap welded boiler tubes, 511
Lap welded pipe, 507
Laps, shell plating, 260
Latent heat, of food products, 600
of steam, 342
Launches, 673
Launching, 227
Launching calculations, 228
Launching data, 232, 233
Launching devices, 231
Launching ways, 228, 232, 233
Launching weight, 233
Law of comparison, 226
Lay, 632
Lead, 155
Lead of valve, 400
Leg boiler, 366
Length, of boiler and engine rooms, 305,
310
for freeboard, 208
Lloyd's, 166
over all, 166
between perpendiculars, 166
for tonnage, 169
Lifeboat, distance from vessel when
heeled, 679
Digitized by VJiOOQLC
730
INDEX
Lifeboats, 663, 664, 665
capacities of, 669, 670, 671
motor driven, 664
Life buoys, 668, 673
Life jackets, 668
Life preservers, 672
Life rafts, 664, 672
Life-saving equipment, 663
Light cruisers, 248
Lighters, wood, 282
Lighting, electric, 541, 544, 547, 550,
552, 556
of saloons, 288
Linear measure, 2
Line carrying guns, 682
Line loss, electric, 536
Liners, 258
Linking up, steam engines, 403
Liquid measure, 4
Lloyd's, 235
Lloyd's Register of Shipping, 234
Load, horse power to raise, 628
Loading cargoes, 683
Loads, curve of, 295, 296
for blocks, 648
Locomotive boiler, 366
Log, steam engine, 703
Logs, weights of, 18
Logarithms, properties of, 28
table of, 29
Longitudinal bulkhead, 268, 299, 320
Longitudinal metacenter, 181, 182, 190,
192
Longitudinal system, Isherwood, 253
war vessels, 244
Longitudinals, 263
Lowering boat, heel of vessel, 678
Lubricating oil, 358, 359
Lubricating system, gasoline engine, 484
steam engine, 417
Luff tackle, 650, 652
Lumber, shipping weights of, 18
See also Timber and Wood
Lumber cargoes, 694
Lumber schooners, 283
Lumber steamers, 327
Luminous buoys, 673
Lundin lifeboats, 670
Machinery, maintenance of, 700
Machinery foundations, 277
Machinery operating. See Operating
Machinery specification headings, 301
Machinery survey, 700
Machinery weights, 304, 310
Magnesia, 162
Magnetos, 489
Main drain, 602
Maintenance, hull, 696
machinery, 700
Make and break ignition, 551
Malleable iron, 72, 121
Manganese bronze, 156
Manganese steel, 112
Manifold, 530
Manila, 634
Manila rope, 636, 634, 631
Manila rope blocks, 648
Margin plank, 285
Margin plate, 261
Marine insurance, 710
Marine steam engines, 393
Mariner's measure, 2
Marline, 637
Masts, rake of, 680
Materials, cu. ft. per ton, 16
piping, 527
rivet, 104, 110, 117
shipbuilding, 111-165
specific gravities of, 13
strength of, 70-110
weights of, 13
Mean effective pressure, calculation of,
410
trial, 421
Measurement of draft, 389
Measuring screws, 289
Mechanical and electrical units, 23
Mechanical equivalent of heat, 341
Merchant vessels, types of, 238, 309
Messenger chains, 624
Metacenter, longitudinal, 181, 182, 190,
192
transverse, 173, 174, 176
calculations for, 175, 177, 179, 181
tables of heights, 174, 202
Metals, non-ferrous, 155
Metric conversion table, 7
Metric system, 4
Metric unit of heat, 341
Midship section, battleship, 246
motor ship, 500
Digitized by VJiOOQLC
INDEX
731
Midship section, schooner, 283
steamers, 241, 242, 254,257
Midship section coefficient, 172
Millimeter-inch conversion table, 5
Mineral wool, 163
Modulus, of rupture, 70
section, 53, 129
Molded breadth, 166
Molded depth, 167
Moment of inertia, 50
calculations, 297
sections, 52
structural shapes, 129
water plane, 176
Moment to alter trim, 190, 192
Monitors, 248
Mooring lines, 642
Motor boat, percentage cost of parts,
337
speed formula, 224
Motor boat propellers, 317, 431, 434
Motor boat wiring, 550
Motor boats, data on, 317, 318
Motor driven lifeboats, 664
Motor schooner, estimate on building,
334
Motor ships, data on, 316
repair costs of, 336
Muntz metal, 157
Mushroom anchor, 660
Nails, 293
Nautical mile, 2
Naval brass, 157
Net tonnage, 169
Neutral axis, beam, 76
vessel, 297
Nickel steel, 113 '
Nickel steel forgings, tests of, 113, 116
Nipples, 526
Nominal horse power, 22
Non-ferrous metals, 155
Non-metallic materials, 162
Norske Veritas, 237
Nuts, bolts, 524
propeller, 430, 699
Oakum, 162
Oats, cargo of, 691
Oblique -triangles, formulae for, 41
Ohm, 531
Ohm's law, 532
OH, 353
chill or cold test of, 356
color of, 356
density of, 355, 359
fire point, 356
flash point, 356
fuel, data on, 354, 356
kerosene, 478
storm, 681
stowage in barrels, 685
stowage in cases, 686
viscosity of, 356, 359
Oil barrels, 21, 355
Oil burners, 362
Oil burning systems, 360
Oil cargoes, 684
Oil carried in inner bottom, 321
Oil carriers, construction of, 320, 257
data on, 326, 295
fire extinguishing apparatus for, 325
pumping arrangements in, 323, 325 .
stability of, 320, 684
ventilation of, 578
Oil consumption, 316, 350, 421
Oils, Beaumg gravity of, 354, 355
for boilers, 356
heat values of, 356
for internal combustion engines, 357
lubricating, 358, 359
specific gravities of, 354, 355, 356
weights of, 354, 356
Open hearth steel, 111, 116
Operating boilers, 385
Operating cost, Diesel engines, 334, 335,
496
geared turbines, 496
motor ships, 334
steam engines, 496
Operating Diesel engines, 499
Operating electric generating sets, 560
Operating motors (gasoline engines),
491
Operating pumps, 477
Operating refrigerating machines, 600
Operating, ship, 683
steam engine, 419
Operating surface condensers, 453
Ordering rivets, 104
Ordering shapes and plates, 130, 258
Overhauling boilers, 386
Digitized
by Google
732
INDEX
Packing, 526
Paddle wheel engines, 314, 329, 397
Paddle wheel steamers, 311, 329
Paddle wheels, 436
data on, 314, 437
slip, speed, revolutions and pitch of,
436
Paint, anti-corrosive, 279
anti-fouling, 279
copper, 281
cork, 289
red lead, 279
Painting, boiler room, 281
crew's quarters, 288
engine room, 281
hull, 279
staterooms, 287
wood, 288
Panels, electric motor, 565
Panting stringers, 268
Parabola, area of, 33
Paraboloid, volume of, 38
Parallel, lamps wired in, 540, 550
Parallelogram, area of, 33
Passenger steamers, data on, 310, 312
Pass-over valves, 415
Peak tanks, cement in, 278, 698
draining of, 604
Perishable products, keeping of, 587
Petrol, 358
Petroleum and products, 353
Phosphor I ronze, 156, 71
Pickling steel plates, 121
Pillars, 268
Pintles, rudder, 275
Pipe bending, 519, 527
Pipe, brass, 518
bursting formula for, 90
butt welded, 507
butt welded, bundling schedule, 20
comparative areas of, 521
for cooling coils, 596
copper, 518
couplings, 526
coverings, 163, 165
fittings, 528
flanges, 522, 528
gaskets for, 526
lap welded, 507
length of thread, 526
nipples, 526
Pipe, square feet in, 571
steel, 507
strength of wrought iron, 507
threads, 525
trade customs, 507
wrought iron, tables of, 508, 509
test for, 507
Pipes, friction of air in, 585
loss of pressure in, 520
water flow in, 520
Piping, ammonia, 596
carbonic anhydride, 596
Piping oil burners, 362
Piping systems, materials for, 527
Piston rod, formula for, 414
Piston, steam engine, 414
Piston valve, 394, 399
Pivoted davits, 676
Plank, margin, 285
Hanking, of wood vessels, 282
deck, 284
Plating, shell, 258 .
Plenum system, 576
Plough steel wire rope, 637, 639
Plugs, fusible, 379
in shell plating, 261, 699
Plumbing, 606
Plumbing fixtures, 606
Policies, marine insurance, 711
Polygon, area of, 33
Polyhedron, measures of, 36, 38
Portable conductors, 545
Portland cement, 162
Powering vessels, 222
Powers of numbers, 26, 29
Pressure, absolute, 449
atmospheric, 344, 448
gauge, 449, 344
Prices, of barges, tuga\ schooners, etc.,
333
of boilers, 337
of steamers sold in 1915-1916, 331
of steam engines, 337
Prices, costs and estimates, 331
Primary batteries, 554
Primer, wood, 288
Priming of pumps, 476
Prism, measures of, 36
Prismatic coefficient, 171
Producer gas, 479
Propeller nuts, protection of, 699
Digitized by >
nvJ^v^
INDEX
733
Propellers, back of blade, 424
blade thickness of, 432
bosses of, 430, 432
data on, 310, 426, 431, 432, 434
developed area, 425
diameter, 424
disk area, 425
disk area ratio, 425, 426, 430
driving face, 424
edges of, 424
finding pitch of, 428
formula? for slip, speed, revolutions
and pitch, 428
helicoidal area of, 429
keys for, 430
motor boat, 317, 431, 434
number of blades, 425, 426
nuts for, 430
nuts, covering of, 699
pitch, 424, 428, 430
pitch ratio, 424
pressure on, 430
projected area, 310, 425, 429
right or left-handed, 424
shape of blades, 424
slip of, 425, 427, 42S, 430, 434
struts for, 273
thrust of, 424, 429
turbine ship, 429
weights of, 432
Proportions, extreme, of a vessel, 168,
212, 294
Propulsion, i.h.p. for, 222
turbo-electric, 444
Propulsive coefficient, 223
Protective deck, 245
Pulleys, 652
Pumping arrangements, oil carriers,
322, 325
Pumps, air, 459
centrifugal, 474
circulating, 462
duty of, 472
freight steamer, 477
hand, 605
installing and operating, 477
lifts of, 471
priming of, 476
types of, 470
Purchase on capstan rope, 630
Purchases, 650
Pyramid, measures of, 36
Quadrant davits, 676
Quadrant, rudder, 621
Quarter sawing, 157
Radians, 3
Radiators, steam, size required, 569
Radius of gyration, 50, 52
Raised quarter deck vessel, 242
Rate of combustion, 350
Reaumur thermometer, 25
Receiver pressure, 421
Reciprocating pumps, 470
sises of, 473, 474
Reducing valves, 529
Refrigeration, 587
for cold storage room, 598
for products, 599
gas to produce, 598
ton of, 595
Refrigerants, 591, 594, 601
Refrigerating machinery, 591
space taken by, 587
Refrigerating machines, horse power for,
595,600
location of, 601
operating of, 600
rating of, 600
Refrigerating rooms, insulation of, 587
ventilation of, 591
Refrigerating systems, costs of, 337
Register ton, 2, 169
Registro Nasionale Italiano, 237
Registry, 169
Relief valves, cylinder, 415
Repair costs of motor ships, 336
Resistance of vessels, 225
Return tube boiler, 366
Reverse frames, 256
Reverse gears, 483
Reversing engines, 416
Rheostat, 565
field, 543
Rift sawing, 157
Rigging, ship, 645
yacht, 643
Rigs of vessels, 679
Ring buoys, 673
Rivet diameters, Lloyd's rules for, 102
reduced to inches, 108
Digitized by
Google
734
INDEX
Rivet materials, 104
Rivet steel, boiler, 110, 72
hull, 117, 72
Riveted joints, 105
Riveted plates, bearing Value of, 107
Riveting in oil carriers, 321
Riveting shell plating, 260
Rivets, cone head, weight of, 110
countersink depth for, 102
length for ordering, 104
number in 100 lbs., 109
proportions of, 102
shearing strength of, 105, 107
signs for, 103
strength of, 104
tensile strength of, 104
types of, 101
working load for, 92
Rockets, 682
Rope, cast steel wire, 639, 641
formulae, 642
hemp clad wire, 636, 637
hoisting, data on, 632, 634
kinds of, 634
length for splices, 646
manila, weight and strength of, 636
trade terms, 632
wire, 637
flattened strand, 638, 639
measuring of, 640
Rope capacity, of a drum, 628
Rope hitches, 633
Rope knots, 633
Ropes, strength of, 640
Rotating davits, 673
Round-cornered squares, sizes of, 140
Rounds, sizes of, 137
Rudder, chain to, 624
pintles, 275
power to turn, 623
pressure on, 623
Rudder areas, 276
Rudder quadrant, 621
Rudder stock, diameter of, 274
Rudders, 274
Runner and tackle, 650
Rupture, modulus of, 70
Safety, factors of, 75, 518, 527
Safety valve, 376
Sagging, 298
Sailing vessels, 240. 282, 319
motor, data on, 318, 320
Saloons, lighting of, 288
Salting wood vessels, 282
Salt water, 8, 12
Saturated steam, 343
properties of, 345
Sawing wood, 157
Scale, boiler, removing of, 388
Schooners, construction of, 282, 283
data on, 319
motor, data on, 318, 320
Scotch boiler, weight of water in, 307
Scotch boilers, data on, 364, 365, 366
proportions of, 363
Scouts, 249
Screws, brass and iron, wood, 290, 291
lag, 289, 293
measuring of, 289
Screw threads, bolt, 52*
pipe, 525, 526
Searchlights, 553
Seasoning wood, 158
Secant of an angle, 40 ♦
Secants, table of, 43
Section modulus, 53, 129 *
Sections, properties of, 52
Sector of circle, area of, 33
Segment of circle, area of, 33
Separators, steam, 416
Series, lamps wired in, 540
Series motors, 561
Shackles, tests of, 95, 96
Shaft, torsion formula for, 89
Shaft bearings, 418
Shaft horae power, calculation of, 447
steam consumption per, 312, 448
Shafting, formulae for, 412
Shallow draft steamers, 328
Shearing strain, 70
Shearing strength of bolts, 93
Shearing strength of rivets, 105
Shearing stresses, curve of, 295, 298
Shearing value of rivets, 107
Shear poles, stresses in, 98
Sheaves, block, number of, 654
Sheer, 210
Shellac, 288
Shell plating, 258
plugs in, 261, 699
reinforcing at bulkheads, 271
Digitized by >
nvJ^v^
INDEX
735
Shell plating, stresses in, 297, 298
Shelter deck vessels, 239, 240
freeboard of, 216
Shifting boards, 689
Shifting of coal, 693
Shifting of grain, 688
Shipbuilding channels, 129
Shipbuilding materials, 111-165
Ship calculations, 166-233
Ship chartering, 703
Ship construction, systems of, 253
Ship equipment, 615
specification headings, 301
Ship fittings, strength of, 91
Ship operating, 683
Ship's dimensions, 168, 212, 294
Ship's rigging, 645
Ship's section, stresses in, 299
Ship's side, heat through, 567
Ships, data on, 309
friction constants for, 227
frietional resistance of, 225
powering of, 222
strength of, 294
types of, 238
war, 243
wood, 282
Shipping measure, 2
Shipping organizations, 234
Shipping terms, 716
Shipping weight, 1
Shipping weights of lumber, 18
Shunt motors, 561
Shutting off boilers, 386
Side girders, 262
Side wheel steamers, data on, 313, 314,
315
Signal lights, 546
Signal wires, 546
Signals, Ardois, 566
Silicon steel, 113
Simpson's first rule, 34
Simpson's second rule, 35
Sine of an angle, 40
Sines, table of, 43
Sinks, 607
Skylights, 286, 287
Slide valve, 394, 399
Sluice valves, 602, 606
Societies, classification, 234
Soft coal, sizes of, 352
Soft wood sizes, 160
Solenoid brakes, 566
Sounding rod, 606
Spanish burton, 650
Spark coils, 487
Spark plugs, 490
Specification headings, 300
Specific gravities, of materials, 13
of oils, 354, 355, 356
Specific heat, of food products, 600
of steam, 341
Spectacle frames, 274
Speed, motor boat formula for, 224
Speed of vessel, and engine revolutions,
224
Speed table, 434
Sphere, measures of, 36
Spherical sector, measures of, 36, 37
Spherical segment, measures of, 36, 37
Spherical zone, measures of, 36, 37
Spikes, boat, 293
Splices, rope, 646
Springs, 90
Sprinkler systems, 614
Square bars, sizes of, 140, 143
Square edge flats, sizes of, 140
Square measure, 2
Square root, 27, 29
Squares of numbers, 29
Stability curves, 183
Stability, notes on, 189, 683, 688, 693,
694
of oil carriers, 320, 684
Stack, area of, 363
rake of, 680
resistance to draft, 393
temperature, 393, 421
Stairs, 287
Stanchions, 268
Standard gauges, 123
Starting valves, 415
Stateroom bulkheads, 285
Staterooms, painting of, 287
Steam, 341
coal required to generate, 349
consumption per i.h.p., 342, 421
consumption per s.h.p., 445, 446, 447,
448
consumption and cylinder cut-off, 405
dry, 343
efficiency of, 342
Digitized
by Google
rr
736
INDEX
Steam, for evaporators, 468
kinds of, 343
latent heat of, 342
saturated, 343
properties of, 345
specific heat of, 341
superheated, 343 (
specific heat of, 343
temperature of, 344
temperature and vacuum of, in con-
denser, 456
total heat of, 342
volume of, 348
wet, 343
Steam capstans, 630
Steam engine generating sets, 559
Steam engine log, 703
Steam engines, back pressure in, 396,
456
bearing surfaces, 414
calculation of i.h.p., 410
coal consumption and cylinder cut-
off, 405
coal consumption per i.h.p., 411, 421
connecting rod formulae, 413
crank sequences, 396
cut-off, 395, 405
cut-off and steam consumption, 405
cylinder clearances, 396
cylinder formulae, 413
cylinder ratios, 394
cylinder, steam pressure in, 404, 405
estimated horse power of, 411
expansion in, 394, 395, 405
fittings and accessories, 414
indicator cards, 406
lap, 400
lead, 400
linking up, 403
lubricating system, 417
mean effective pressure, 410
number of expansions by pressure,
405
number of expansions by volumes,
405
operating, 419
operating cost, 496
paddle wheel, 314, 329, 397
pistons, 414
piston rods, 414
pressure in cylinder at cut-off, 404, 405
Steam engines, prices of, 337
setting valves, 404
shafting formulae, 412
size of boiler for, 371
thrust collars, 413
trial trips, 421
types of, 393
valve mechanisms, 402
valve travel, 401
valves, 394, 399, 400
water service, 417
Steam expansion, in engines, 394, 395,
405
in turbines, 439
Steam gauges, 378
Steam heating, 568
Steam lighters, data on, 314, 315
Steam pipe covering, 163, 165
Steam plant auxiliaries, 448
Steam pressure, average, for stroke, 405
boiler, 364, 370, 421
in cylinder, 404
receiver, 421
Steam radiators, sizes of, 569
Steam separators, 416
Steam steering engines, 615
Steam traps, 463
Steam turbines, 437
Steam velocity, 440
Steam winches, 626
Steam windlasses, 624
Steam yachts, data on, 314, 315
Steamers, cargo and passenger, data on,
310, 311, 312, 320
excursion, data on, 313, 314, 315
lumber, 327
shallow draft, 328
Steel, carbon, 112, 114, 116
cast, 118, 72, 116
chromium, 114
chromium nickel, 114
chromium vanadium, 114
coefficient of expansion, 112
elongation of, 112, 116, 72
manganese, 112
manufacture of. 111
nickel, 113, 72
properties of, 111, 116, 72
rivet, 117, 110, 72
silicon, 113
structural, 114, 116, 72
Digitized by
Google
INDEX
737
Steel, tungsten, 113
-vanadium, 114
S^eel bars, flat, weights of, 149
weights, circumferences and areas of,
143
Steel boiler tubes, 510, 511, 512
Steel columns, 84, 85, 86
Steel forgings, tests of, 113, 116
Steel hawsers, 644, 646, 631
Steel heads, maximum sises of, 128
Steel pipe, 507
Steel plate gauges, 124
Steel plates, diamond checkered, 125
maximum sises of, 128
ordering, 130
pickling and galvanising, 121
tests for, 114, 116
weights of, in lOOths of an inch, 122
variations in, 115
Steel pkttes and sheets, weights of, 124,
126, 127, 128
Steel shapes, ordering, 130
Steel wire nails, 293
Steering chain, size of, 624
Steering gear arrangements, 617, 620
Steering gear, steam and electric, 615
Steering gear transmissions, 620
Steering engines, installations of, 616,
618
Stem, 272, 116
Stephenson valve mechanism, 402
Stern frame, 272, 116, 698
Stern tube, 273
Stern wheel engines, 329, 397
Stern wheel vessels, 329
Stokeholds, ventilators to, 579
Stop valve, 377
Stopwaters, 272
Storage batteries, 554
Storm oil, 681
Stove bolts, 132
Stowage of oil, in barrels, 685
in cases, 686
.Stowage space of materials, 16
Stowing cargoes, 683
Strain, 70
Strapping of wood vessels, 282
Stream anchor, 659
Streams, water, 612
Strength of materials, 70
of rivets, 104, 105, 92, 107
Strength of ship fittings, 91
of timber, 74
of tubes, pipes and thin cylinders,
formula for, 90
of wrought iron pipe, 507
structural, of vessels, 294
ultimate, 71
Stress, 70
Stresses, in cranes, derricks and shear
poles, 98
in materials, 71, 73
in shell plating, 297, 298
Stringers, 268
Stroke, steam pressure at end of, 404,
405
Structural details, 253
Structural features, merchant vessels,
238
Structural shapes, 129
Structural steel — Am. Bureau of Ship-
ping Rules, 114
Am. Soc. of Testing Materials, 115
Lloyd's requirements, 114
strength of, 72, 114, 116
Structural strength of vessels, 294
Struts, propeller, 273
Submarine chasers, 252
Submarines, 250, 300
Suction head, 471
Sulphur dioxide system, 613
Superheated steam, 343
specific heat of, 343
Superheaters, 381
tests of, 383
Surface blow valve, 378
Surface condensers. See Condensers
Surfaces of solids, 36
Survey, hull, 696
machinery, 700
Switchboards, 543, 546, 549
Switches, 543, 546, 550
Swivels, 657
Tables, writing and mess, 287
Tackles, 650
power gained with, 652, 654
Tangent, of an angle, 40
Tangents, table of, 43
Tank top, ceiling for, 285
covering for, 263
Tankers. See Oil carriers
Digitized
by Google
738
INDEX
(
Tees, 140, 141
Temperature, combustion chamber, 303
of fire, 353
furnace, 303
hot well, 421
injection water, 421
of steam, 344
stack, 303, 421
uptake, 303, 421
Temperatures, cold storage, 588
Tension, 70
Tensile strength, of bolts, 03
of materials, 71, 112, 113, 116, 110,
120, 523
Tension in hoisting rope, 634
Tests, for carbon steel, 112, 114
for cast steel, 118
for rivet steel, 117
for steel plates, 114, 116
for steel shapes, 114
of cast iron, 121, 71
of eye bolts, 05
of hooka, 04, 06
of insulating materials, 164, 165
of lag screws, 203 *
of shackles, 05, 06
of steel forgings, 113
of superheaters, 383
of turbo-generator sets, 560
of turnbuckles, 07
of woods for hardness, 158
of wrought iron, 120
Thermometer scales, table of, 24
Thermometers, 25
Thermotanks, 571, 577
Threads, on bolts, 524
on pipe, 525, 526
Three-wire system, 540
Throttle valve, 414
Thrust, propeller, 420
Thrust bearing, 418
iWist horse power, 24
Thrust shaft, collars on, 413
Tiller rope, 640
Timber, feet board measure in, 0
properties of, 74
See also Wood; Lumber
Time charter, 704
Time measure, 2
Time policy, 713
Timers, 487
Timon charter, 705
Tin, 155, 72
Titan bronse, 156
Tobin bronse, 156, 71
Ton, cubic feet per, 16
of refrigeration, 505
register, 160, 2
shipping, 2
Tonnage, gross, 160
length for, 160
net, 160
Tons, per inch of immersion, 170
per inch of immersion curve, 170
Torpedo boats, 240
Torpedo boat destroyers, 240
Torpedo tubes, 246
Torpedoes, 246
Torsion formula, 80
Towing, 223
Towing machines, 631
Transverse bulkheads, 268, 320
Transverse metacenter. See Metaoenter
transverse
Transverse system, 253
Trapezoid, area of, 33
Trapezoidal rule, 33
Trapezium, area of, 33
Traps, steam, 463
Trawlers 327
Trials, 421, 312, 443, 445, 447
Triangle, area of, 33
Triangles, solution of, 41
Trigonometry, 30
Trigonometric formula), 42
Trigonometric functions, 40
Trim, 100
moment to alter, 100, 102
Trim calculations, 101
Trim lines, 102
Trimming tanks, cement in, 278
Trip charter, 703
Troy weight, 1
Trunk vessels, 243
Tubes, brass, 511, 514
bursting, formula for, 00, 518
cleaning boiler, 387
copper, 511, 513, 514, 510
trade customs, 507 ;J
Tugs, construction of wood, 282 fet
data on, 314, 315
Tungsten steel, 113
ui
Digitized by
Google
1
INDEX
739
Tunnel, draining of, 604
Tunnel vessels, 330
Turbine auxiliaries, 448
Turbine generating sets, 560
Turbine ship propellers, 429
Turbine ships, data on, 312, 440, 443,
444, 445, 446, 447
trials of, 312, 421, 443
Turbines, Alquist gearing for, 444'
calculation of, s.h.p., 447
data on, 312, 437
efficiency of, 446
expansions in, 439
geared, 442, 445, 312
hydraulic transmitter for, 444
steam consumption of, 446, 443, 448
types of, 439
weight saved with, 446
Turbo-electric propulsion, 444
Turbo-generators, rating of, 544
Turnbuckles, tests of, 97
Turning engines, 416
Turret vessels, 243
Two-wire system, 540
Ultimate strength, 71
Unions, 526
Unvalued policy, 713
Uptake temperature, 393
U. S. Steamboat-Inspection Service, 238
Vacuum, 421, 454
to find, 455
See also Trials
Vacuum gauge, 454
Vacuum and steam temperature in con-
denser, 456
Valued policy, 713
Valve, check, 529, 378, 471
safety, 376
' sluice, 602, 606
stop, 377
throttle, 414
Valve travel, 401
Valves, cylinder relief and drain, 415
Diesel engine, 499
for pipe, 528
internal combustion engine, 484
steam engine, 394, 399, 400
starting or pass-over, 415
surface and bottom blow, 378
Vanadium steel, 114
Vaporizers, 482
Varnish, 288
Ventilation, 575
air required, 575
of engine room, 579
of oil steamers, 578
of refrigerating rooms, 591
Ventilating systems, 576
laying out, 584
Ventilators, 579
Versed sine of an angle, 40
Vessel heeled, distance lifeboat from,
679
Vessels, rigs of, 679
Viscosity of oil, 356, 359
Volt, 531
Voltages, 532
Voltmeter, 543
Volumes of solids, 36
Voyage policy, 713
War vessels, 243
boats for, 673
Warping winch, 629
Washing out boilers, 387
Waste lines, 609
Water, data on, 8
boiling point of, 12
density of, 12
flow in pipes, 519
quantity through a hole, 195
weight of in Scotch boilers, 307
Water, evaporated, equivalent units of,
23
in boilers, 371, 375
per lb. of coal, 349
Water gauge, 379
Water injection temperature of, 449,
457, 421
Water plane, center of gravity of, 51
coefficient of fineness, 171
moment of inertia of, 176
Water pressure — air pressure, 577
Water service, steam engine, 417
Water streams, 612
Water tube boilers, 368
space occupied by, 370
weights of, 308, 370
Water tube and fire tube boilers com-
pared, 370
Digiti
zed by G00gk
740
INDEX
Watt, 531
equivalent value of, 23
Wattmeter, 543
Wave forming, 225
Weight, of water, 8
in Scotch boiler, 307
Weight curve of a vessel, 294, 295
Weights, of a battleship, 247
of boiler covering, 307
of boilers, 306, 370
of brass sheets and plates, 126, 127
of cone head rivets, 110
of copper sheets and plates, 126,
127
of Diesel engines, 309
effect of moving, 203
of engines, 305, 306
of flat steel bars, 149
of fire bars, 307
of fire bricks, 307
of hulls, 303, 310
formulas for, 302
of lag screws, 292
of logs, 18
of lumber, 18
of machinery, 304, 310
per i.h.p., 304
of materials, 13
of miscellaneous units, 19
of oil carriers, 326
of oils, 356
of propellers, 432
of square and round steel bars, 143
of steel plates and sheets, 124, 126,
127
of steel plates in lOOths of an inch,
122
of structural shapes, 129
of water tube boilers, 308
Well deck vessel, 230
Wet steam, 343
Wetted surface, 172, 421
Whale boats, 673
Whips, 650
Winches, 626, 629
Windlasses, 624
Wire rope, 637
hemp clad, 636, 637
measuring of, 640
Wire rope blocks, 648
Wire rope flattened strand, 638, 639
Wireless equipment, 680
Wires, electric, carrying capacities of,
534,535
gauges of, 538
measurement of, 533
running of, 545
sizes of, 537
Wiring, motor boat, 550
steamer, 547
Wiring gasoline engines, 551
Wiring systems, electric, 539
Wood columns, formulae for, 85, 87
safe loads for filler, 288
grain of, 157
hard and soft rises of, 159, 160
hardness of, 158
heat values of, 352
kinds and properties of, 74, 160
painting of, 288
primer, 288
sawing of, 157
seasoning of, 158
See also Timber, Lumber
Wood screws, brass, 291
iron, 290
Wood vessels, 282
Working boat, 664
Working stress, 73, 74
Wrought iron, 120, 116
Wrought iron pipe, data on, 507
tables of, 508, 509
Wrought iron pipe columns, safe loads
for, 88, 89
Wrought iron tubes, bursting pressures
of, 91
Yachts, steam, data on, 314, 315
Yacht rigging, 643
Zees, rises and weights of, 142
Zero, absolute, 344
Zinc, 155, 72
Zinc strips, boiler, 701
condenser, 453
hot well, 463
sea connection, 698
stern frame, 698
Digiti
zed by G00gk
0)
Digiti
zed by G00gk
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