SCANTLINGS 483
the Classification Societies, against the scantling numbers of the ship,
in the form of a series of Tables which give very precise information
regarding the structure. The Tables are not of much interest to anyone
other than those responsible for the building of the ship, nevertheless
they illustrate to the casual reader the scientific basis underlying the
design and construction of a ship, and, incidentally, they impress us
with the fact that no one has a free hand to build a merchant ship in
any way he fancies.
The numerals are derived from the dimensions of the proposed
ship, the bigger the ship the bigger will her numerals be and the heavier
will be her scantlings. The depth D of the proposed ship regulates
the spacing and the sizes of the side framing and the dimensions of
the floor plates. The numeral D is qualified by another number
referred to as d when entering the Tables, d being the vertical depth
at the middle of the ship's length measured from the top of the
beams at the side of the lowest deck down to the top of the floors, or
to the top of the double bottom.
The "First Longitudinal Numeral" is length X depth (LxD), and
this number regulates the sizes of all the components forming the
double bottoms also flat plate keel, shell plating, propeller boss plates,
etc. The "Second Longitudinal Numeral" is Lx(B+D), that is
breadth added -to depth and multiplied by length. This number
regulates the scantlings of the topside structure, such as sheer strake,
stringer plates, deck plating, etc. See also page 542.
The dimensions of Caledonian Monarch are length between per-
pendiculars 430 feet, moulded breadth 56 feet, moulded depth
30 ft. 6 in. -
Her numerals would be D = 30'5
First numeral L X D = 430 X 30-5 = 13115
Second „ L X (£+D)=430x(56+30-5)=37195
The Tables give also the scantlings for bulkheads, masts, rigging,
anchors and cables and the general equipment of the ship.
Shipyard workers and draughtsmen refer to the Tables as required
and do not attempt to memorise the contents of the fifty-six Tables
given in the Regulations, but they may remember from daily experience
, and repetition work some of the relative dimensions of the more
important parts of the structure they arc working on*