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VOLUME Il 
1969 
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(a. U.S. NAVAL OCEANOGRAPHIC OFFICE 
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SCIENCE and the SEA 


VOLUME Il 


1970 


U.S. NAVAL OCEANOGRAPHIC OFFICE 


For sale by authorized Sales Agents of the U.S. Naval Oceanographic Office, 
Washington, D.C. 20390; also by 
the Superintendent of Documents, U.S. Government Printing Office, 
Washington, D.C. 20402 - Price $1.00 


SP-132 


pes, 


FOREWORD 


Science and the Sea, a collection of selected Pilot Chart Articles, was 
first published in 1966 as a means of acquainting teachers and students alike 
with some of the more practical aspects of the familiarization with the sea 
as regards to oceanography, hydrography, and navigation. Since then, the 
publication, now designated as Volume I, has been widely distributed and has 
thus received the acclaim of readers in many walks of life. As proof of the 
great interest generated by Volume I, numerous requests have been made for 
a further compilation of similar articles. 


Volume II of Science and the Sea, the second in this proposed series, 
features ten additional articles covering a wide range of oceanographic, 
hydrographic, and navigational subjects. The articles included were orig- 
inally prepared for presentation on the reverse sides of issues of the Pilot 
Chart of the North Atlantic Ocean and the Pilot Chart of the North Pacific 
Ocean. These charts are published monthly by the U.S. Naval Oceanographic 
Office to provide mariners with a graphic synopsis of oceanographic, hydro- 
graphic, navigational, and meteorological conditions that prevail in those 
waters. 


Volume I of the booklet may still be procured by ordering from the 
Superintendent of Documents, U.S. Government Printing Office, Washington, 


D.C. 20402. Price 75 cents. 
Ia Se : 


Captain, U.S. Navy 


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—— 


TABLE OF CONTENTS 


Page 
GEOLOGICAL OCEANOGRAPHY 
Historical Wevelopmentt reac rnccwees arses sista. ceter eres Ao cise yee cic ke a eeaged cals mere ae eB 1 
Continental Shel tzemetpen treet cane enn etme Nn csc ey AL 0 Ml ah AUS eatin ed ars leet 2 
Continental eS lopepey rece eee a nyse user eetise eit Onocti Au Are Ee A ee io eee 3 
Whew Des p= OCeanpllOormmet eee eesti teen wht vey cee) ccs eta ace caress arasuanycna Ne maeyae enegePan eae 3 
Sedimentsionst hes @ceanwhlOorsssr merc ereccescael nel maimasr ees «kare uere ee hee pene cne pea Sees 5 
Maoare tice Meas unements) price ttre eE-the te ian ehh CON tran ree eee ge Le 6 
GravityaMleasure ments s seceyscric ny 5 vcs ose nsec gey ose uo seen aussi tosmeneere siete walls eee eens 6 
SEISmMIcwMeASUE MEMES rte eae ceva eens oe TT ete ele ea SaHG Pa Stee oe orev dere es anes eae 6 
HeatuhlowaWeasurementsiic: cmos tes sis a enccencs cieleucn ssh sta eaGatasiai ant sense cocoa sqetiw eaten seen eo a 
COnelUSTO meee ere ceN ee ial mere ate lary May sian ceeaten ah its eee ens ieee d rae ane Perey ee SE OS 7 
OCEAN WAVES 
her Surbace: ofthe seavisnay CSS ayrge caenes sisted acl eaacn santana aie anceps CUNT esis esac 9 
hheghamilywlreerotaOceanm Waves aricacs oc cle tomers Sehcies G, al seucuis) soem Ie 10 
BirthvandeD evelopmentiofawindaWiavesmnaacnnoceicen aoc arte oem err iol 
WindaWaves) Limited by; Blowing, heir Lops... 4.4 5040202665 see) eae aoe oe: 11 
Ine: IBETEAY SOQCMEUIIN Oh! WN. SEE a0 ccob cn coconupscooudcosangeovcudcdoc00s0C0UCGN US 12 
SpectralehiltersrandwWiaverHonecastsmemsn-aneemaracceee mae cemecmaeees cima 13 
HotsioteNewaWays tomMeasurenwiaviesaasnee cane done aerate race e rence: 14 
RorAllemhings “Theres Comes aim Cys, or cee neat ae atonsioia. n cromen ini wae arorene ra enemies 15 
SURVIVAL AT SEA 
Be Alo and Omnme nites scr scnvcrn ci ducaren tow sec nea ays oxiataayere a a katie eRe a eee 18 
JAINA LON TINE) Ohl Oe are ormote Seeicm oaroce Gara Cem aa ora ook ae ee era cea clade 18 
WisetotaClothingsastayMloatinesAidkeae ne nesoeo enor ooerOOOne cn oon ee ae aneee 19 
SS WALID INT IN pay tee ea tee ENA Ered eau heamyeorev eesti ck ake ema Tahlenciel cL ca EUG PORE ioe es eee 19 
LAIR), Crest e010 | TSKOW AINE lon coctgta eanto erchefoie Ream tonctotmisiea ais ciaieva Peco ore gta trois at-o atria clots ote 19 
LOO a 5: execs eecreie ene eee: Coatre ce ene gtt eer ek Cee eh teers ol Cece eR Geel le corgi acet amet NIN cee et 20 
Mine Cations sot tien ale aes: caper evsg Nee aoe eases Sa neice eis W aiy SST Se oar EOP SE Glos SR ISIEp aE aR 21 
FVESCUC MIP Srey a sesanera tence dete ys a neincle Bes oe tae aud eine weeks, cama onent genera Sli eeaee aera sale 21 
IMramp Overboard ier tien,ce ated hee en a sues oie RA CATE Heo cleo Meee eects canna tueta tive eucimiacd nu. gie aus, 22 
SSH OATES) wad cei eleva eter ti oie entre cones rte ale Ee ree cnr EE crete eae mn seeeene ro ee ee eiee retlnreaar aie 24 
NAVIGATIONAL HINTS 
Gait SROYSKOKG VO) ole Maire sana cpmtcr a pten oltnnaetcnstet ave aieealet cee me eae a tonaR IRIN a 3. criti Heltah te 25 
Wepths—Shoals=—Currentsh..csen teen o ae hae Ge eel heme hase aku eee kee ste 25 
EV CHOSS OUTIG TT ere een SCRA UT oe Oe UES OPT a ism ee a 26 
INI GhteVASiOnVH Oni ZO. ccs oes esccit ace Ba Sen So OMI OO TNA DORMS EE gai eemOe 26 
Sigshtwe ror Compensavionec y.csoce sei sas asc eisai ao a usuet ancl suemeuouruc cimeuteys- out aeeuaiacectees 26 
Latitude by Meridian Altitude Below the Pole.....................00002.20000005- 27 


NAVIGATIONAL HINTS (Continued) 


MixHRelia bilityac: 2c acs eee ee e  Oe IRE ha cian eRe Cee ee 27 
5S) of eterts A OBI) ce ee tenets cin apetcneietione ae Mecale treaties Ga Blears aid.n it arr eG RS TOA LES Oar 28 
CompassyAhonment sen see 2. oer eee CEE ee RCO Cee re re ee ee 28 
Mechanical Wefects acs enka ees ee eee eee ere eee 28 
Retained Mapnetismcj a) cect ss ser nig Ree ee Ee screens 28 
WocaltMagnetic Disturbancernyys.4 jaa oe a nO ee eee eee 28 
Kadior Directions bind erste at ere ea er ree CEE eT ee 29 
Sound’Sional Ca wtionie.neccrye ca. ceeeec eee hone ee os ee aT eee 29 
Radar Wand fall ls eesre neteee, bee can artes fers ites neces alec) eran Coes ert gee a 29 
Te ShbersaDe tection cs catenin ae Hear eee EL eI ae ere ee ee 30 
FANS ROIN CPATICHONIN Deseret pas ee ee PEI Ee EO ee eee 30 
GOMC US TON eee ease emer s eee choses Site ne ere OT ee CVC STOR Ce ee 31 


FISHERIES VESSELS AND GEAR 


Classes :andtMethods!) 5. nc2 5 ich Biot tyson ie See Re ee 33 
Jteyaye bil One \hea enone tearatre toe Seen RRA Eo ie mi PHP e aoe EocR Aastra Goons orcs ROSALIA RO OL aS 33 
MT AWEES raage gta ros a Nerd ieee Soaked SOE KE eNO re ET Re EE Ee 33 
PANG at ra WillT Oe snc Weasy or ts he ae HOV oT Ag ead so Ten Ee 35 
MONS =WinegPus hin Gecko oe ek ee ree SOE ee ee eee 30 
ID TTL CET Serre cesar Na eae che eS Pace CR Pe rant cat Tes yea A aR gy EE SRE ara oe 36 
RUS CR SEINES Sis tase enero eee eee one ert TE oe ye eee 37 
IVA TAY all a1 recess ererotsnore ero ics sate tends eae ad eR TO Oe eee eee 37 
SHrimM PehiSherles ter. -tee seats eae case ee hone eee ee 38 
SRUTAS ects ssapive bg ny Rouse aise teen ar aie an slapd OBNSTS oto oa RL TERETE eee 38 
AN USTSTA A 00V8) Clires te Sueete pene ee RoR a Rete ene roeeenr rari ae ANS tenes DUR ES ENT AD as Nga eee OS Cede 38 
PSH Ca CTA Revs eich oy RCRA ca aS eS cemE Tee eeOUT  CSRS LSA Ye ele PN ey en EE 39 
Wieirs. PoundtiNets janis Trapsisis & cis cics heer eee er eee 39 
ON SCOTS Fete SP ey Mcrae des ee Pe Rare sea SAP Ene PRR Sie RE ci =e Ey 08 eee 40 
TODS ter JHISHETIGS 3 8 sis. ein fyi keceiat anaes cee eee Bere ee ee eee 40 
Gonelws ion ess, 3/ars ccs eres paves ey VU ees sl oro A ET OE 40 
SHIPS-OF-OPPORTUNITY 
IB OFNCOLINECESSIEY es sescrg st se oe cee Gak ieee Fie eena Aero a Tn ee 42 
INO tealvIN Giw Ald Gaerne ete cite csi te tis we canst seilailo ceva eee eee ea ee 42 
eX N/A EAS) Acree ent er COs in etch en FOR ee AUD VesOOD Ss CA a| IN 42 
The Near Surface Reference Temperature System...................2..00..00000- 44 
FrOJECtw NG PLUM Chia aacietsr ini ics crswsse sar eee Uae Eee aren ere EY ee ET eet 45 
DISCUSSION ascites eis states. 4 daly aa Sete keen aI Tee ec eee ee 46 
CONCLUSION RF cere rte ate areea elements sete Lee doOa e e PRE 48 
OCEAN STATION VESSELS 
IMeteorolosicalt Serva et crc ne tle sis yee acy nee TET EEE OE ae 49 
OceanopraphicyMatarCollection=e] eon ener ere Ee ee ee CEE Er ea tee 50 
INavigationalwAid shave misma: no sitet Mice cones LRU ee a ae ene ee 50 
SearchrandhRescueinnes.. secu ects e sea Oe Eee ee ee ea eee 52 
Operationsire nies oe eee se tees Hee oe ie CEN AO Ee eee 53 
AtGlAN tI — EMIStORYy sees deer te, sears arctarie: EMA cy ec ety Ae ie 54 
PACT LIC == FMI CON yA sess a tayteeren ce Recaro sa ae 55 
PS AN) 9) 910) Une Reetaees steer ss erat nee epee te eter eye ee naa NGS ALO Ae cm. 5 56 


THE DISTRIBUTION OF DISCOLORED WATER 


irate OCHA CLO Tig ee ee eS EN IPoIB Seare sastis tne dtar shlasraneesrtonai.ceativtig stesmles 57 
IRUGKHONAY5-4-ob acon Ob Colbe cin doa diptan ora dua choiiora a prcidsa a Otero GBI oto er Bi Ioctn ieee Rae raccriaas oan 57 
(GBS CS ee eee oe CTE DC EME coppice capa mibisca mea autiSis nani tus 57 
TOS HetT ORTEGA eG halarcl a cee las Bas lah hao Bs ms eel CH MORENO EERE .c: Gred etestcstes eu cy relRCDR ete ERS See SER 58 
IMTOO. oon ba a cone o se TAeU cea Oneal poe cdiess aacuCl oo 7 ob u mobomoe oacocdor 60 


OCEAN CABLES AND DEEP-SEA TRAWLERS 


InternationallConventioniofeMarchi4 1884 ann. .5 earner eae see eee 65 
for the Protection of Submarines Cables 
COLLISIONS—1969 
TESaV(ETAOYG LE YOX CKO 01 tates eros deeaccte seth waa cc Oo CEN RAE ES SIE APOC CELLS Sy EERE Gt ims hs con Rie ee 69 
Case 1 
NEWB OS 6 og Bele oo eG Ob GIG Ory OSE OO rE A MN ice re Ia ea eae ty URAC eae yr een 8 70 
SATORU NAST Sino ce cree shes esac PSN eH aa EEO SCL Ore et pr eS oe cee ase 72 
Case 2 
INIGTEEATE NW Els cece, oe che eA O Asai tS ERIN G0 COO Oot en GaGk CE TOPCE Te CE Ce aren Rar ener eae 73 
/NTOBURYSTISE eile exes cnentcecu ate cS oust oO SINE ARE ca unto arils cota erte Scene merc rece ene crane 74 
Case 3 
SIN Feairera G1 Vie ee pee ese eae ee 5 SCOR OIC CCRT emp cliatiors sane ne Mcliag Ren Ga eaos Pet edatios 76 
PASTA y SIS Eye eee uence cucencbele cityeiseee rate let Siamese Sie aeie een ela a behsh aes Gen cpectedi: nO eta 79 
Case 4 
INIEWE ENG Ay eiote ne Soke SEER Eek ISNT Ere ae ones Sratnlotn oat enna Memcetten tcc creer tec neice 719 
At ally SIS eye ie raregs ome eieas iste Goce te red nee erareeh he reat RS rice te a ope sits sts auwec a hinee metenege 82 
GCOMCLUSTO eval TAS teas eT ROO TAN See ise ahh staat eu aren sens an/eeNejtintesereteitanets 83 


vii 


GEOLOGICAL OCKANOGRAPHY 


By Andries Van de Ree 
Maritime Safety Division 
U.S. Naval Oceanographic Office 


Geological Oceanography is the application of the science of 
Geology to the ocean basins. As such, it is directed toward all 
aspects of geology. It includes the investigation and analysis of the 
topography and the composition of the ocean floor, the study of vol- 
canism, magnetics, gravity, seismism, heat flow. 

In the last two decades great strides have been made in our 
knowledge of the ocean floor and its sediment layers. Three factors 
have contributed to the advancement in this field. Firstly, instru- 
mentation has progressed rapidly, giving us better tools for explo- 
ration—improved echo sounders, more accurate electronic position 
finding systems, gravity meters operating on surface ships, new 
acoustic devices, electronic computers, and submersibles of various 
sizes. Secondly, the U.S. Navy, in cooperation with others, has be- 
gun surveying accurately the unknown part of the ocean floor to 
publish bathymetric (deep measuring) charts urgently needed by 
nuclear submarines capable of diving to great depths. Thirdly, in the 
last few years the government has made additional resources avail- 
able for both theoretical and applied ocean research. 

The ocean floor, covering approximately 72 percent of the earth’s 
surface, is divided into areas with the following common features: 


1. The continental shelves, the relatively shallow areas border- 
ing the continents and a few large islands. 

2. The continental slopes and rises which usually extend from 
the outer margin of the shelves to the deep sea floor. 

3. The deep sea floor, the domain with great depths where 
abyssal plains are interspersed with great mountains, exten- 
sive ridges, deep basins, valleys, canyons, troughs and 
trenches. 


Before discussing each of these areas and some of the other 
fields comprising Geological Oceanography separately, a background 
is provided for the lay reader. 


HISTORICAL DEVELOPMENT 


For centuries, geology, as a physical science, was explored by 
scientists who occupied themselves almost entirely with charting the 
land and investigating basic geological principles. Geological 
Oceanography was neglected until the latter part of the eighteenth 
century when James Cook led a scientific expedition which not only 
measured the ocean depths, but took many temperature observations 
from 1772 to 1775. Soundings of real oceanographic importance were 
taken in 1840 when Sir James Clark Ross obtained soundings of more 
than 2,600 fathoms in the Antarctic. 

In those days, soundings were made with a hemp line. Lowering 
and raising the lead to take a deep-sea sounding took hours. An 
improvement in sounding was introduced in the middle of the nine- 
teenth century by Lt. Matthew Fontaine Maury, U.S.N., using a can- 
non shot attached to a ball of twine, which ran out rapidly. When 
the bottom was reached, the twine was cut and the depth determined 
from the length of twine remaining in the ball on board. However, 
this method did not produce a bottom sample, so that one of Maury’s 
co-workers, Midshipman Brooke, U.S.N., invented an automatic de- 
vice for detaching the extra weight from the sounding lead when it 
hit bottom, with the result that a lighter line could be used to raise 
the lead. Lt. Maury issued a bathymetric chart of a part of the 
North Atlantic containing fewer than 200 soundings. 

In 1882, the U.S. Commission of Fish and Fisheries launched the 
Albatross, the first ship ever built in this country for oceanographic 
research. Under the leadership of Agassiz, the ship took more deep- 
sea soundings than any other vessel up to that time. 

An important innovation in sounding was introduced by Thomson 
(Lord Kelvin) in 1874 by using piano wire for sounding line instead 
of hemp or twine. 


In the early twentieth century, a real boon to the progress of 
oceanographic research was the development of the echo sounder. 
It was a major breakthrough in increasing our knowledge of the 
relief of the ocean floor. In 1923, the U.S. Coast and Geodetic Survey 
used the first echo sounder on the Guide, and from 1925 to 1927 the 
Meteor of the German Atlantic expedition made an extensive inves- 
tigation and obtained numerous echo soundings in the middle and 
southern part of the Atlantic Ocean, providing the scientific com- 
munity with detailed profiles of the ocean floor in the explored area. 
Comparing these profiles with those available from the continents, 
it was found that irregularities in the ocean bottom in some areas 
are as great as those on land. Echo-sounding lines of the U.S. Navy, 
the Coast and Geodetic Survey, and others proved that in other 
oceans, irregularities are also common. 

Shallow areas of the ocean floor are being explored by geologists 
by swimming with scuba gear, which consists of one or more cylin- 
ders of compressed air strapped to the back and a tube leading to 
the mouth for breathing. 


Another means of increasing our knowledge was the develop- 
ment of the deep-sea camera. In 1893, Boutan took underwater pic- 
tures off the Mediterranean coast of France, but it was not until 
1938 that Ewing and his group started to experiment with cameras 
which could be used on the deep-ocean floor. Since then, many pic- 
tures have been taken aiding the scientist in the examination of the 
sea floor and the study of the sediment types. A team of scientists 
of the U.S. Naval Research Laboratory has taken pictures of the 
ocean floor where the submarine Thresher disappeared about 260 
miles east of Boston. The photographs proved, without doubt, the 
fateful end of the submarine. 

To transmit data rapidly, the research vessel Geronimo, operat- 
ing in the Equatorial Atlantic Ocean in September 1963, sent ocean- 
ographic information directly to the National Oceanographic Data 
Center, Washington, D. C. via the Syncom satellite. 

The Oceanographer and the Discoverer, oceanographic survey 
ships of the U.S. Coast and Geodetic Survey, are equipped with auto- 
matic data processing systems to provide readings of shipboard 
instruments and perform calculations for ships’ laboratories simul- 
taneously. Similar systems reflecting the latest state of the art have 
also been installed on the latest U.S. Navy oceanographic research 
ships. 

Fortunately for the advancement of marine geology, other 
avenues of exploration were brought into play. In 1930, Otis Barton 
constructed a diving sphere, called the “bathysphere’’, which was 
lowered into the ocean by a wire. A more recent vintage of the div- 
ing sphere is the bathyscaph Trieste, which descended to a depth of 
5,966 fathoms in the Challenger Deep in the Pacific Ocean. 

Submersibles to explore the oceans by close observations are 
being developed in ever-increasing numbers. One of the latest exper- 
iments was the descent of the manned submersible Sealab II, 57 
feet long and 12 feet in diameter, to a depth of 210 feet off San 
Diego, California. A group of men lived and worked under pressure 
for several days, occasionally outside the submersible. Pioneering 
to habitate the ocean floor has begun. 

Another attack on the secrets surrounding the deep-sea floor is 
the Mohole Project, which has the objective of piercing the earth’s 
crust and reaching the earth’s mantle. To accomplish this goal, tech- 
nical know-how should provide the tools to drill through some 15,000 
feet of rock in a location where the ocean is about three miles deep. 

Preliminary investigations were conducted by the drilling barge 
Cuss I, which drilled a number of holes, the deepest being 601 feet 
into the ocean bottom in water about two miles deep. The tests 
showed that for drilling purposes, the platform should be kept 


SCIENCE 


at a horizontal distance from the drill hole not to exceed five per- 
cent of the depth. This requirement was satisfied by measuring by 
sonar the distances from the platform to sonar buoys moored on the 
ocean bottom, feeding these data into a computer which regulated 
the direction and pitch of the platform’s propellers to keep its posi- 
tion within allowable limits. 


Figure 1. Submersible DEEPSTA R-4000, capable of diving to 4000 foot depths 


for periods up to 24 hours. Built by Westinghouse Electric Corporation. 


2 TV cameras 
Vertical 


propulsion motor 


Forward 
trim tank 


Main propulsion Viewing ports 


motor Batteries 


Mechanical arm 


Figure 2. Cutaway drawing of submersible STAR III equipped with external 
mechanical arm that has interchangeable “hands”. 
Courtesy General Dynamics Corporation. 


THE CONTINENTAL SHELF 


The Continental Shelf is the shallow platform adjacent to the 
continents or some large islands, stretching out from the shore toa 
depth where a marked increase of slope to greater depths is noted. 
Its special feature, the shallowness, dampens the swell which rolls 
in from the deeper parts of the ocean, and makes the establishment 
of harbors along its edge feasible. Because most of the fish in the 
ocean is on the shelf, fishermen have been busily engaged in this 
area. 

This platform has been better explored and surveyed than the 
remainder of the ocean floor because of the shelf’s importance to 
the mariner who avoids the shoals and obstructions, and uses sound- 
ings and bottom samples as aids to navigation. However, investi- 
gation of the shelf is an endless task, because tectonic activity fre- 


MARIANA TRENCH 
—10,914 m 


METERS 


LUZON. STRAIT : | 


AND THE SEA 


GRAY FEATHER 


BANK 


quently changes the bottom contours considerably as was experi- 
enced when the U.S. Coast and Geodetic Survey took soundings in 
an area in Alaska affected by the earthquake occurring in 1963. 
Moreover, erosion and deposition cause alteration in the bottom 
relief. 

In recent years the shelf has gained added importance for the 
large amount of minerals found on and beneath its floor. In 1946 
the United States took possession of the mineral rights on the con- 
tinental shelf adjacent to its shores; the 100-fathom curve was de- 
fined as its outer limit. 

In many other parts of the world, however, the outer limit of 
the shelf, where a marked increase in slope is noted, lies at a different 
depth. According to F. P. Shepard, the average slope of the shelf in 
the world is 0° 7’, its average width is about 42 miles, and the aver- 
age depth of the outer margin is 72 fathoms. It has been estimated 
that the shelves cover about 7.6 percent of the earth’s surface. 

Formerly, the shelf was believed to be always a gentle sloping 
plain, but this is only true in specific locations. Often the shelf is 
hilly with many irregularities. An example of shelves with a rough 
bottom is found adjacent to the land masses which had been covered 
by glaciers. Deep depressions, such as the fjords in Norway and 
British Columbia, or deep troughs, such as the Gulf of St. Lawrence 
and the Straits of Juan de Fuca, penetrate far into the land, and 
often extend across the shelves, but with shallower depths seawards. 
Those deep bays frequently have many basins containing muddy 
sediments combined with gravel and sand. Many banks, rising close 
to sea level, extend along the outer shelf and are covered by sand 
and gravel, among which are the Grand Banks of Newfoundland 
and Georges Bank off New England. They furnish the best fishing 
grounds in the world. Numerous hills, mostly mantled with rock or 
covered with boulders or gravel, are sometimes located on the inner 
shelf. 

Shelves with a smoother bottom are those with elongated sand 
banks and depressions. This bottom relief is found on the shelf 
adjoining the shore of New Jersey and resembles the topography on 
land, the plains with their sand ridges. These shelves are mostly 
covered with sand or a combination of mud and sand. In areas sub- 
ject to severe storms or strong tidal currents, such as the North Sea 
or off Nantucket, elongated banks are shifting constantly and have 
to be sounded frequently to warn the mariner of changing condi- 
tions. A narrow shelf which is subjected to strong currents is found 
on the east coast of Florida and off Cape Hatteras. 

On the Pacific coast the shelves located off young mountain 
ranges are mostly narrow and deeper than the average or are lack- 
ing entirely. An interesting example of a missing shelf is on the 
west coast of South America where the land declines with a 5-degree 
slope from the crest of the Andes Mountains to the bottom of a 
trench offshore. 

The shelves which are the widest and the shallowest are found 
off river deltas and in areas where coral growth is plentiful. On the 
northern coast of Siberia, where large rivers carry loads of sedi- 
ments, the shelves are the widest in the world. Wide shelves can 
also be found at the mouth of the Amazon River, in the Yellow and 
Bering Seas, in the Gulf of Siam, in the Persian Gulf, and in the Bay 
of Bengal. Shelves where coral growth is extensive are found off 
Australia. The shelf off Queensland is about 170 miles wide and very 
shallow. The Great Barrier Reef of active coral growth lies on its 
outer part. 

Interesting features in the bottom relief of the shelf are the 
submarine valleys. They are sometimes loaded with sediments but 
others which are scoured by tidal currents can be easily detected, 
as is the case of the valleys off the coast of Brittany. 

A discontinuous submarine valley lying slightly below the sur- 
rounding area is located between Java, Sumatra, Malay Peninsula, 
and Borneo. Hurd Deep with a depth of 94 fathoms and the Ouessant 


SATAWAN | 


GEOLOGICAL OCEANOGRAPHY 


Trough with a depth of 105 fathoms in the English Channel are dis- 
continuous submarine valleys presumably cut out by the strong tidal 
currents prevailing. 

The most common sediments found on the shelf are sand, mud, 
and gravel-pebbles, cobbles and boulders. In addition, rare sediments 
are bombs, ash, or pumice of voleanic matter; seaweed and other 
marine plants; oysters mostly found in brackish water; and sponges 
which grow on the shelf in tropical areas. 

The depth of the sediment layer varies in different locations. 
Off the east coast of the United States, the thickness of the sedi- 
ments under the shelf is about 17,000 feet. According to G. E. Murray, 
the coastal plain and inner shelf at the Gulf Coast of the United 
States and Mexico have a great wedge of sedimentary strata which 
thickens to about 6.5 nautical miles under the present coast line. 

The lowering of the sea level that happened during the ice 
periods when a greater part of the continents was covered with ice 
masses seems to be the main factor to explain many of the present 
conditions of the continental shelves. Formerly, it was believed that 
the shelves were cut by wave action at present sea level. However, 
most shelves join the coast without great cliffs and have outer 
limits that are too deep to be caused by wave action. 

Proof of the former subsidence of the sea level may be found by 
the presence of coarse sand, presumably deposited when the sea 
level was lower, on the outer shelf and by the existence of river 
channels which have been found across the North Sea and the 
English Channel. According to R. A. Daly, the sea level was lowered 
about 246 feet during the periods of maximum ice advance. 

As one-half of the ice on the continents has melted so far, an 
increase in the world temperature will eventually flood the coastal 
plains around the world. It has been observed that the sea level 
throughout the world is rising about 21% inches in a hundred years 
because of the melting of glaciers. 


THE CONTINENTAL SLOPE 


The area between the continental shelf and the deep-ocean floor 
is marked by steep slopes. The steep upper part is called the contin- 
ental slope; the lower part with gentler slope has been named the 
continental rise or deep-sea fan. According to Shepard the steepness 
of the slope from the shelf outer margin to a depth of 1,000 fathoms 
averages 4°17’. The greatest gradient has been found in the Bartlett 
Trough off Santiago, Cuba, with a slope of 45 degrees. 

Although most continental slopes are continuous, others are 
interrupted by continental borderlands, areas with terraces or basins. 
These borderlands are at greater depths than the valleys of the con- 
tinental shelves but at lesser depths than the deep-sea floor. 

It is believed that the continental slopes were originally formed 
by fracturing of the earth’s crust. The numerous earthquakes appear- 
ing on or near the continental slopes substantiate this belief. Renewal 
of fracturing and submarine landslides causing sediment-laden 
density currents to flow near the bottom prevent the accumulation 
of large sediment deposits on the slope. 

After submarine cables were laid across the ocean, it was found 
that breaks appeared in them on the continental slopes. These breaks 
are believed to be caused by landslides, the sediment on the slope 
becoming liquified, or turbidity currents flowing along the bottom. 


Submarine Canyons 


The winding V-shaped depressions with many branches that 
extend down most continental slopes are similar to the canyons on 
land are called submarine canyons. 

One hundred years ago the assumption was made that submarine 
canyons were old river valleys, that had subsided below the sea level. 
Since the canyons extend often to the bottom of the continental 
slope, this theory has been abolished. Several geologists believe 
that the principal cause of the existence of the canyons is fractur- 


PACIFIC 


160° 150° 140° 130° 


120° 


ing of the sea floor. The winding nature of the canyons with its 
branches prompted other scientists to find a different explanation. 
The opinion has now been widely accepted that submarine canyons 
were cut by the turbidity currents flowing near the bottom. 


Marginal Plateaus 


Separated from the continental shelf by a section of the conti- 
nental slope, the marginal plateaus are areas with a shelf-like appear- 
ance. Often the surface is irregular in profile such as those of the 
marginal plateaus off Recife and Rio de Janeiro, Brazil, and west of 
Angola. The Blake Plateau located off the east coast of the United 
States is rather flat with depths ranging between 400 and 600 fath- 
oms. The bottom consists of rock or a similar substance which is 
difficult to core. There are many explanations for the existence of 
this plateau. One opinion suggests that due to slow subsidence dur- 
ing many centuries, the latter shelf sank to lower levels, but sedi- 
ment deposits did not build up because of the powerful current of 
the Gulf Stream. 


The Continental Rise 


The sediment-covered plains bordering the continental slope are 
called the deep-sea fan or the continental rise. Its main features 
are the gentle slope and smooth bottom. In most areas the continen- 
tal rise is bordered by the abyssal plains; in others, for example off 
California, the beginning of the abyssal hills marks the lower limit 
of the continental rise. 


THE DEEP-OCEAN FLOOR 


The deep-ocean floor, a part of the earth’s surface, consists 
mostly of a sediment layer on top of the earth’s crust superimposed 
on the earth’s mantle. Inside the earth’s mantle is the core. 

The earth’s mantle has a volume about 10 times greater than 
the combined volume of the core and the crust. Its inner surface, 
the core-mantle discontinuity, lies about halfway between the center 
and the surface of the earth, and its outer surface, the crust-mantle 
discontinuity, also called “Mohorovicie Discontinuity”, lies about 6.5 
nautical miles under the ocean basins and between 19 and 27 nautical 
miles under the continents. 

The earth’s crust is divided into a top layer of lighter rocks, 
mainly granite and granodiorite, called “sial” for silicon and alum- 
inum, and a much thicker bottom layer of heavy rocks, both peridotite 
and basalt with peridotite of even greater density underneath, known 
as “sima” for silicon and magnesium. The layers forming the earth’s 
crust are not evenly distributed over the earth’s surface, but at the 
margins of the continents the sial layer becomes thinner to seaward 
or stops entirely. In the Pacific Ocean, the sima layer is exposed 
over vast regions; in the Atlantic and Indian Oceans, however, a thin 
stratum of sial covers the floor. 

By topographic features the deep-ocean floor can be divided into 
two regions: the oceanic ridges and rises, and the abyssal floor 
subdivided into the abyssal plains and the abyssal hills. 

A mid-oceanic ridge is an elongated elevation on the sea floor 
with steep irregular slopes in the middle of the oceans. Bottom- 
water temperatures taken in the east and west basins of the Atlantic 
by early oceanographic expeditions ascertained that the shallow 
area in the middle of the ocean, previously discovered by soundings, 
was a ridge, named Mid-Atlantic Ridge. It extends from Iceland to 
a southerly latitude of about 57 degrees. Points on the ridge are 
almost equidistant from the outer edges of the continental slopes on 
both sides of the Atlantic. The highest part of the ridge rises about 
2,000 fathoms above the deep basins on the sides to about 1,000 
fathoms below the sea level. The highest peaks in the ridge project 
above water, and form islands as the Azores, St. Paul Rocks, Ascen- 
sion, and Tristan da Cunha. The ridge is intersected by an important 
break, called ‘“Romanche Furrow”, just northward of the equator. 


28°45'S 


SHOAL 
(NR. GONZALEZ 1.) 


110° 


SCIENCE AND THE SEA 


The tectonic features of the Mid-Atlantic’ Ridge seem to be a part of 
a 40,000 mile long world-encircling belt which passes through the 
South Atlantic, around the Cape of Good Hope into the Indian 
Ocean, around Australia, up the Eastern Pacific, through the Arctic 
Basin and the Norwegian Sea. South of the Azores, this ridge is 
very complex with many mountains and valleys. In the South 
Atlantic, the ridge has a layer of sediments from about 300 to 650 
feet thick, but in other zones sediments are sparse or entirely 
lacking. 

Some elongated valleys extend down the slopes of the Atlantic 
basins with steep sides and flat floors that are 10 to 100 fathoms 
lower than the surrounding area. These depressions are from about 
three to five miles wide. Terraces like plateaus are found on both 
sides of the Mid-Atlantic Ridge. 

Oceanic rises are elongated elevations with gentle smooth slopes 
having continuous layers of oceanic sediments. The lack of terri- 
genous sediments and the sharp change in slope at the base of such 
rises indicate that the turbidity currents have not affected these 
areas. 

In 1947 an expedition of the Woods Hole Oceanographic Institu- 
tion made the important discovery that large areas of the deep- 
ocean floor in the North Atlantic are flat, almost level plains with 
a bottom gradient of less than 1:1000. These plains are called abyssal 
plains and have been found on the deep-sea floor throughout the 
world mostly at the base of the continental rises. 

Current opinion suggests that these plains were produced by the 
deposition of coarse sand and shallow-water fossils carried by tur- 
bidity currents fanning out on the sea floor. These plains only exist 
in areas where the turbidity currents are not blocked by the bottom 
relief. Since turbidity currents cannot pass island ares and trenches, 
the Pacific has fewer abyssal plains than the Atlantic. Abyssal 
plains have been observed also in marginal seas, such as the Western 
Mediterranean, the Gulf of Mexico, and the Caribbean. 

Although many soundings have been made over the deep-sea 
floor with standard echo-sounding apparatus, large errors in these 
instruments made a study of the abyssal plains next to impossible. 
To make a more effective study of these plains feasible, a Precision 
Depth Recorder (P.D.R.) was developed in 1954. A more accurate 
curve of the bottom relief was obtained on an 18-inch-wide fatho- 
gram by recording depths in a 400-fathom range. For example, a 
depth of 3,745 fathoms will be shown when the fathogram records 
depths between 3,600 and 4,000 fathoms. Even at such great depths 
a slight variation can be easily observed on the fathogram. An ac- 
curacy of the P.D.R. and Precision Graphic Recorder of 1 fathom in 
3,000 has been achieved. 

An additional improvement in sounding occurred with the devel- 
opment of a high-resolution narrow-beam echo-sounder, electron- 
ically stabilized, so that the return echo represents the accurate 
depth under the ship. The reception of echoes from surrounding 
slopes has been greatly reduced. 


Deep-sea channels at the seaward end of submarine canyons, 
cut out in the continental slope, often extend across the boundary in 
the abyssal plains. On the seaward side of most abyssal plains, 
adjoining areas are covered by abyssal hills. These hills vary in 
height between 50 and 200 fathoms and are between two and six 
miles wide. They are most numerous in the Pacific, where they 
cover most of the floor. If an area is almost completely covered by 
hills, it is called an abyssal-hills-province. Abyssal hills are found in 
abundance in basins separated from land areas by trenches, ridges, 
or rises. Two strips of abyssal hills run parallel to the Mid-Atlantic 
Ridge for nearly its entire length. The Western Atlantic Abyssal- 
Hills Province, southeast of Bermuda, is over 500 miles wide. 

A seamount, mostly of voleanic nature, is an isolated circular or 
elliptical elevation on the ocean floor, rising at least 500 fathoms 
above its surroundings and having comparatively steep slopes. 
Soundings, taken with a Precision Depth Recorder over seamounts 
often show craters on their tops. 


Resembling a huge underwater spear, 
this corer, used to extract samples of the 
sea bottom, is checked by a scuba diver. 


When the topography of the ocean floor is similar to the abyssal- 


| hills-province but with higher peaks, the area is designated asa 
j “seamount province”. A typical seamount province can be found in 


Baja California, where 1,000 seamounts are located in a region 
covering 410,000 square miles, Considering the number of seamounts 
present in a densely-surveyed area, it has been estimated that the 
number of seamounts in the whole Pacific Basin may reach roughly 
10,000. 

Seamounts having flat tops are called “guyots” or “tablemounts”. 
To find an explanation for the flat-top appearance of the guyot, a 
topographic survey was made with echo sounders of five tablemounts, 
followed by dredging and coring for rocks and sediments. The 
results suggested that the tops of the guyots have once been at or 
near sea level, when erosion took place, but have sunk on account of 
subsiding of the ocean floor and the guyots, or the rising of the 
sea level. 

Although seamounts and guyots are present in the Atlantic, 
greater numbers are known to exist in the Pacific. Guyots, fewer in 
number than the seamounts, appear in three linear groups—the 
Emperor Seamount Chain, south of Kamchatka; the Marcus-Necker 
Ridge, west of Hawaii; and the region stretching out from the 
Marianas to the Marshall Islands. Furthermore, 10 guyots, close 
together, in the Gulf of Alaska, seem to be forming parallel lines. 
Other guyots exist as isolated mountains. 

Trenches are long and narrow depressions with steep sides in 
the ocean floor. These trenches attain the greatest depths of the 
ocean, and are often adjacent to island chains with active volcanoes 
and earthquake activity, while others border the coast of Mexico, 
Central and South America. 

For many years the Mindanao Trench off the Philippines was 
thought to be the deepest, but soundings have disproved this belief; 
greater depths have been found in the Tonga Trench of the South 
Pacific Ocean, the Mariana Trench and the Kuril Trench. 

The Middle-America Trench, extending from the southern end of 
the Gulf of California almost to Panama, has been explored most 
thoroughly. It was found, after producing a contour map of the area, 
that the floor was flat in part for several miles across and was V- 
shaped elsewhere. A thick layer of sediment was found underneath 
the flat floor, while the V-shaped floor was free of sediment. Several 
submarine canyons cut the landward wall of the trench, and a group 
of basins with varied depths up to 3,700 fathoms and some hills, 
presumably submarine volcanoes, are spread out on the floor. 

Many scientists indicated the connection between the trenches, 
and earthquakes and volcanoes. It is generally believed that the 
trenches are surface expressions (faulting of the crust) of large- 
scale processes acting deep within the earth. Along the trenches 
earthquakes are more frequent than in any other region in the 
world. Near the trenches tremors are of shallow origin, but farther 
landward the earthquakes originate at greater depths and their 
origins reach depths exceeding 200 miles when on a line 200 miles 
removed from the trench. This phenomenon has been observed for 
all trenches of the world. If the origins of the earthquakes farther 
landward do not increase in depths, the trenches are lacking. 


c 
EQUATOR 


ANDES MTS. ATLANTIC OCEAN { 
CAPE PALMAS AFRICA 


SOUTH AMERICA 


GEOLOGICAL OCEANOGRAPHY 


CONTINEN 


Features prevalent beneath the sea. 


Many trenches located in regions with earthquake activity are 
paralleled by linear groups of volcanoes. In the same manner, the 
Aleutians, the Kurils, and the Marianas are are-shaped island chains 
located on the concave side of the arcuate trenches. 

In the sea floor of the northeastern Pacific, H. W. Menard found 
four great parallel fractured zones with an average width of sixty 
miles between 1950 and 1953. The Mendocino Fracture Zone, the 
northernmost, extending westward from Cape Mendocino for a dis- 
tance of more than 1,400 miles, stands out for its steep slope, called 
“sea scarp”, which in places is over 10,000 feet high. Menard also 
discovered many smoothly sloping areas extending to the deep-sea 
floor around some island masses, which he called archipelagic aprons, 
presumably caused by lava flows originating from the islands. 

Depressions, resembling canyons, have been found in the abyssal 
floor. They often have steep walls and flat floors. East of 
Newfoundland four of these depressions have been discovered, which 
are part of a continuous canyon extending for a length of 1,500 miles 
from Greenland to the Southeast Newfoundland Ridge. Other ocean 
canyons have been found in the equatorial Atlantic and in the 
Hikurangi Trench. 

Oceanic islands, mostly limited in area and voleanic in character, 
rise from the ocean floor far from the continents. Large continental 
islands, such as Iceland, Greenland, and New Zealand are not in this 
category. Japan and the Aleutians are in a borderline class. Oceanic 
islands are either a part of a chain or are isolated. Older oceanic 
islands in the tropics are often surrounded by reefs, and the voleanic 
base may be covered by limestone. Oceanic islands, which appear to 
be isolated, are sometimes the highest peaks of oceanic ridges such 
as in the Atlantic, South Pacific and Indian Oceans. 

Volcanic oceanic islands in the Pacific Ocean are often located 
in linear groups, such as the Hawaiian, Society and Marquesan 
Islands. These islands and their ridges are built of lava, and rise 
from submarine ridges, which may be caused by faulting. When 
voleanoes are spaced far apart as those in Tubuai (Austral) Islands 


SAUDI ARABIA 


RED SEA PERSIAN, GULF 


356-697 O - 69 - 2 


Group, their lava output has not been large enough to build a ridge 
between them. 

A ring-shaped reef lying at or near sea level enclosing a lagoon 
is called an atoll. Most of thern rise from the ocean floor, but others 
are found on the continental shelves. Kwajalein in the Marshall 
Islands, the largest existing atoll, covers about 840 square miles. 
Most atolls on the ocean floor have probably been produced by coral 
growth on top of truncated voleanoes. Basalt, a voleanic rock, has 
been obtained from the slopes of some atolls in the Marshall Islands. 


SEDIMENTS ON THE OCEAN FLOOR 


Since the Challenger Expedition (1872-1876), cores of bottom 
samples have been extracted from the ocean floor. In the beginning 
cores were only one foot long, but after the development of the 
piston corer, cores up to 70 feet have been raised. 

According to calculations made by P. Kuenen, the average thick- 
ness of the sediment layer in the ocean basins should be about two 
miles. However, observations made with sound waves indicate that 
the depth of the sediment layer in the Atlantic averages about 3,200 
feet, and in the Pacific about 1,600 feet. E. L. Hamilton suggested 
that the lower parts of the sediment layer have become solidified 
into consolidated sediments. When sound waves are used to measure 
the sediment layer, they are reflected by the interface between the 
consolidated and the unconsolidated sediment layers. Sediment thick- 
ness has now been measured along 150,000 miles of track. 

Sediment types can be arranged according to their origins— 
terrigenous, biogenous, halmyrogenous, and cosmogenous. Terrig- 
enous sediments originate from the continents, and are the results 
either of mechanical and chemical breaking down of the rocks or of 
voleanic activity. These particles in minute size can be widely dis- 
tributed by ocean currents over the whole ocean floor and can be 
found in red deep-sea clay. If these particles are of different sizes, 
such as gravel and stones, they originate from moraines and were 
transported by icebergs over the ocean areas. Terrigenous sediments 


| 3 


MT EVEREST 
{8848 m 


HONG KONG" 


8000— 
6000-] 
4000 
2000 

LEVEL— 
2000] 
4000—4 
6000] 
8000—4 
10000—! 


sualaW 


SCIENCE AND THE SEA 


may be deposited also by dust, which is carried far into the oceans 
by the wind. For example, the dust originating from the Sahara 
Desert has been found in the bottom sediments west of the Cape 
Verde Islands. Sediments of volcanic origin, the fine ash from sub- 
aerial eruptions, may be transported by the wind over wide areas. 
Biogenous sediments are of organic origin, and are divided into two 
types—the remains of animals and plants living on the ocean 
floor, or the remains of animal and plant plankton. Halmyrogenous 
sediments are new direct formations of minerals which are deposited 
when the water is over-saturated with soluble material. Deposits of 
iron and manganese oxides on the ocean floor belong in this category. 
Cosmogenous sediments originate from outer space and consist of 
small balls about 0.2 mm in diameter of magnetic iron or silica. 

Since 1947 M. Ewing and his co-workers of the Lamont Geologi- 
cal Observatory have raised more than 3,000 cores from sediments 
in all oceans and adjacent seas during 44 oceanographic expeditions. 
The study of these cores taken from the bottom of the deep-sea floor 
revealed that deposits of the glacial periods were present in these 
sediments. Layers of gravel and stones, deposited by drifting ice- 
bergs during the periods of the ice ages, alternate with layers 
deposited during warmer stages of the climate. After investigating 
numerous cores, it was concluded that of the four ice periods the 
first one, called the Nebraskan Glacial period, started about 1,500,000 
years ago, the beginning of the Pleistocene, the last epoch of geo- 
logic time. Using the radio-carbon method of dating, the last two 
major maxima of ice ages were fixed at about 60,000 and 18,000 
years ago. 

Sand has been found to cover large parts of the ocean floor. 
There was a general belief that these parts were great submergences 
and that these areas had been located close to the surface. After 
long cores had been obtained from these regions, it was observed 
that the sand layers are imbedded in layers of deep-sea deposits. 
From the map made by David Ericson, it was learned that these 
sandy areas stretch out from the coast in great sea fans and must 
have been transported by density currents. 


MAGNETIC MEASUREMENTS 


Because of the universal use of the magnetic compass for many 
centuries, systematic magnetic measurements at sea were already 
conducted during the voyage of Joao de Castro from 1538 to 1541. 

After the introduction of iron and steel ships, accurate magnetic 
measurements at sea could no longer be taken except in non-mag- 
netic ships, specially constructed for this purpose. An example of a 
non-magnetic vessel was the Carnegie, which conducted magnetic 
measurements from 1909 to 1929. 

Recently the United States Navy has been carrying out “Project 
Magnet”, covering almost the whole ocean area, using aircraft as 
well as ships. These measurements are essential to comprehend the 
whole magnetic field, which is to be divided into parts of internal 
and external origin. Complicated equipment is necessary to conduct 
these observations. 

Much geological information can be obtained from a much sim- 
pler device towed behind a ship or aircraft, measuring the total mag- 
netic force, which is influenced by the magnetic properties of the 
different types of rock lying beneath the ocean floor. 

One of the first attempts to make a detailed magnetic map of 
an extensive ocean area was based on the survey conducted by the 
Scripps Institution of Oceanography, in conjunction with the U.S. 
Coast and Geodetic Survey, off the west coast of the United States. 
The results showed major structural trends of which there is little 
or no indication in the topography. 


GRAVITY MEASUREMENTS 


A body suspended above the earth’s surface when free to move 
will travel towards the earth with an acceleration mainly dependent 
upon the attractive force of the earth and the centrifugal force 
caused by the earth’s rotation. From the many observations with a 
pendulum taken on land to determine this acceleration, it was found 
that the gravitational pull varies in different locations on the earth’s 
surface. One of the reasons causing this phenomenon is the unequal 
distribution of the earth’s masses containing various materials. 

To acquire a more complete picture of the location of these 
masses, gravity measurements at sea became a necessity. However, 
gravity observations taken with a pendulum required a stable plat- 
form. To satisfy this condition, the steamship Fram of the Nansen 
Polar Expedition (1893-1896) took observations when the ship was 


Figure 3. Sensor streamed behind the ship and magnetometer on board are 
used for taking magnetic measurements. 


fast in the ice. Later on, F. A. Vening Meinesz perfected the pen- 
dulum apparatus and conducted many observations around the globe 
from submerged submarines. In recent years J. Lamar Worzel of 
Lamont Geological Observatory has made many investigations in 
this field. 

During the International Geophysical Year, instrumentation had 
improved so much that gravity meters installed on surface ships of 
more than 1,000 tons displacement provided sufficiently accurate 
measurements under reasonably favorable sea conditions. However, 
a correction has to be applied to oceanic gravity measurements for 
depth of water to determine the relative heaviness of material 
underlying the ocean floor. 

From the many gravity measurements in the ocean it was 
learned that the oceanic crust as a whole is probably balanced 
against the continents. However, local variations in the corrected 
gravity measurements are caused by density variations beneath the 
sea bed. Therefore, gravity surveys are useful for making recon- 
naissance to locate features which cannot be detected otherwise. 

Deficient gravity (negative anomaly) has been found above the 
ocean trenches caused, presumably, by a thin crust underneath. 
Seismic shooting, however, indicated that the crust underneath the 
trenches is relatively thick. Further investigation will, no doubt, 
resolve these differences of opinion 

A lack of balance and changes in level have been observed on 
the coasts of the Hudson Bay, which have been rising because the 
layer of ice diminishes throughout the years; the Atlantic Coast, 
however, has been sinking through the build-up of deltas and shelves 
deposited by sediments transported by the rivers. 


SEISMIC MEASUREMENTS 


Our knowledge of the structure and thickness of the sediment 
and rock layers of the deep-sea floor has been advanced considerably 
by seismic measurements. The methods are based upon the measure- 
ment of the time required for sound waves to travel from the place 
of origin, where the vibration is created, to a receiving station. If 
the path and travel time are known, the speed of travel of the sound 
waves can be computed. Because many experiments by laboratories 
have given estimates of the sound velocities in various rocks and 
unconsolidated sediments, a reasonable guess can be made about the 
type of texture in a layer traversed by the sound waves. 

If the underocean faces between the bottom layers are good 
reflectors, and the speed of sound in these strata are known, a 
measurement of the time needed for sound waves to travel through 
each layer and back by reflection indicates the thickness of each 
layer. 

Because conventional echo sounders operate on relatively-high 
sonic frequencies which cannot penetrate far into water-saturated 
sediments, a sounding apparatus, called “Sonoprobe”, has been 
developed transmitting low-frequency sound waves. Penetration 
through a sediment layer up to 300 feet, returning an echo from the 
underlying rock floor, has been achieved by sound waves produced 
by this device. However, an expert has to control continually the 
proper output of sound into the water to detect minor reflections 
from the rock lying beneath the sediment. 


GEOLOGICAL OCEANOGRAPHY 


Sonic waves caused by explosions are capable of penetrating to 
depths of thousands of feet and have been the major tools for sub- 
surface exploration. Because the powerful sound is accompanied by 
many echoes, only large thicknesses of the bottom layers can be 
determined. Using this reflecting-wave method, W. Weibull found 
that the thickness of the sediment layer varied and attained two 
miles in some places of the deep-sea floor. 

Besides the above reflecting-wave methods, systems to study 
the ocean floor by means of refraction waves have been used since 
1937. In the beginning explosions were set off at the ocean bottom, 
and the produced waves were received from a group of seismo- 
graphs lowered to the same level. This costly and time-consuming 
method was abolished and now a method is in use setting off explo- 
sions from one moving ship at regular intervals and receiving the 
sound waves on seismographs placed on a stationary ship. By record- 
ing the travel times of the sound waves caused by these explosions, 
the number and thickness of the layers of sediment and rock can be 
estimated, as well as the speed of sound in each layer—See Fig. 4. 

About two years ago the Coast Guard cutter Woodrush had been 
aiding the University of Wisconsin in explosion seismology experi- 
ments in the Great Lakes to determine the thickness and topography 
of the earth’s crust to points some twenty miles deep or to the so- 
called “Moho” discontinuity. Many shots using explosives weighing 
up to 20,000 pounds were expended. 

MOVING SHIP. 


STATIONARY SHIP 


SEDIMENT 


BASEMENT ROCK 


Figure 4 


HEAT FLOW MEASUREMENTS 


Heat flow from the interior of the earth was first considered 
to be the heat of a cooling molten core. It was assumed that the 
earth was not more than 80 million years old, or the inner part of the 
earth would have lost all its heat. However, with the discovery of 
radioactive substances in crustal rocks and their heat producing 
qualities, it was found that the interior could maintain a high tem- 
perature for billions of years. 

Heat-flow measurements through the sea floor have been made 
in later years with a cylindrical probe about 15 feet long and about 
one inch in diameter. On top of the probe is attached the recorder 
placed in a pressure-tight case. 

To save time, an instrument has been developed in which the 
temperature gradient is measured by an attachment to a corer. By 
measuring the temperature difference between the top and bottom 
of the core and determining in the laboratory the conductivity of 
the sediments in the core, the heat flow can be ascertained fora 
unit area in a unit of time. Contrary to the former belief, that heat 
flow was less from the ocean floor than from the continent, it 
appeared to be actually slightly greater. The heat flow in the Pacific 
floor was determined to average about 40 calories per square cen- 


timeter per year, which equals about the heat flow from the 
continents. 


CONCLUSION 


Although the investigation and analysis of the ocean deep has 
solved many mysteries, we have to make many assumptions and 
guesses regarding the conditions on and below the ocean floor. 
Greater exploration is needed to give us a better understanding of 
the evolution of the earth and a greater knowledge of the ocean 
bottom, so that we may exploit its resources. 

With the growing awareness of the importance of oceanographic 
research, Geological Oceanography, using improved instrumentation 
and employing a greater number of scientists, will progress rapidly 
to meet the demands of mankind. 


By Willard J. Pierson, Jr. 


Their variety and complexity is bewildering 
and vexing to designers of ships, radar, and sonar— 
but their energy spectra are being unraveled 


by tricky analyses of new records from the sea 


Prehistoric man in his childlike simplicity probably threw stones 
into placid pools of water and watched with keen and uncomplicated 
pleasure as ridges and depressions on the surface radiated from the 
satisfying splash in ever-widening circles. More than a century ago 
hydrodynamicists, perhaps with a more sophisticated sense of pleasure, 
developed the mathematics for analyzing ideal periodic and 
aperiodic waves in a fluid bounded by a free surface. Today those 
who study real waves on water—for pleasure or for profit—must 
combine the mathematical methods of time-series analysis with those 
for analyzing nonlinear oscillations, and both of these with elaborate 
statistical methods, to describe and predict the wave-torn configura- 
tion of the sea surface. 

These mathematical procedures are formidable. But they have 
not deterred studies of ocean waves. On the contrary, the number of 
investigators has been growing rapidly. And it increasingly includes 
not only oceanographers, but designers and operators of ships, hydro- 
foil craft, submarines, harbor and other coastal installations, offshore 
driliing platforms, and similar structures—and still others whose 
prime concerns are radar return from the sea surface, or the ambient 
noise background against which underwater sonar systems must 
operate. A few of the practical reasons for studying ocean waves 
are suggested in Fig. 1. 

Investigators of ocean waves are not all motivated by either 
practical reasons or mathematics. To some the challenge lies in the 
art of making difficult measurements. And precision instruments, 
now being used instead of scattered visual observations to record 
waves at sea, also have played an increasingly prominent role in recent 
progress. 

What accounts for the need for such an impressive arsenal of 
observational and analytical tools? Two things—the internal complex- 
ity and diversity of waves, and the many ways they can combine to 
create that confused, chaotic, worldwide geometric entity called the 
surface of the sea. 


The surface of the sea is a mess 


At any instant, this surface covering three-quarters of the earth 
exhibits an amazingly complex and thoroughly random shape. Its 
geometric irregularities span horizontal distances ranging from 
centimeters or less to thousands of kilometers, a range of 9 orders of 
magnitude. Irregularities in the vertical direction are much less, 
however; they span several tens of meters at most. 

The complex pattern created by intersecting waves is not static. 
It changes endlessly through time, and it never repeats itself exactly 
in totality. But individual elements of the total pattern—individual 
kinds and groups of waves—do repeat themselves; they are periodic, 
over a tremendous range in time. The periods of the smallest 
“capillary” ripples, for instance, so important in radar work at sea, 
are less than a second, while a single cyclic oscillation in worldwide 
sea level sometimes takes geologic ages to complete. Few periods of 
ordinary wave motions on water, however, exceed several hours and 
most are much less. 

Small wonder, in the face of this chaos extending over such long 
spans of space and time, that many scientists and engineers came to 
feel prior to the last war that real ocean waves—unlike the ideal waves 
of classical hydrodynamic theory—lay beyond the bounds of possible 
understanding. Yet in the last 15 years, under the stimulus initially 
provided by the need for knowledge of sea and surf conditions during 
World War II, we have partly broken through the “chaos” barrier to 
a reasonably clear understanding of the behavior of several kinds of 
waves. Weevencan—and routinely do—forecast the heights, periods, 
distribution, and travel paths of the dominant kind of ocean waves, 
those generated by turbulent fluctuations in the wind. Such forecasts 
are even accurate, sometimes! 

Does this mean we truly understand ocean waves? Of course not, 
no more than the weather forecaster truly understands the dynamics 
of the atmosphere. To understand waves fully we must know how 
they begin, how they travel, how they interact with other waves, 
with the air above, and with the water and bottom below. And we 
must know how they die. We know none of these to our satisfaction, 
but we do know enough to draw clear distinctions among various kinds 
of waves. 


Ship speed (knots) 


Blip-scan ratio 


2 


Noise (db relative to 1 dyne/em’ ) increases > 


SCIENCE AND THE SEA 


SLOW DOWN SHIPPING 


Wave height (ft.) 


--. CUT RADAR EFFICIENCY 


Range (nautical miles) 


... RAISE SONAR NOISE LEVELS 


10 
Frequency (cps) 


Fig..1. Lowered ship speeds reflect not only added drag imposed by 
higher waves but also voluntary reductions made to ease strain on 
vessel, cargo, or passengers. Radar efficiency, expressed by blip-scan 
ratio, and deep-water sonar noise background both vary with sea state 
(defined in the margin). 


The family tree of ocean waves 


Waves on water differ fundamentally from waves in water. 
Internal waves of various kinds develop below the surface at the stable 
interface between water layers of differing densities. They are 
difficult to study because they can only be detected by the way 
temperature or salinity of the water changes across the interface 
(Fig. 2) and by the slicks of smooth appearing water that they create 
at the sea surface, as they travel along at depth. Although their 
periods are long in relation to their length—internal waves, in other 
words, move very slowly compared to other waves—their height can 
easily reach 50 or 60 ft. They are a quite interesting and important 
class of waves; one line of informed speculation concerning the loss 
of the US nuclear submarine Thresher invoked their influence, for 
example. But waves on water are our prime concern here. 

In order of decreasing wavelength, waves on water include the 
tides, seiches and storm surges, tsunamis, wind waves and swell, and 
the diminutive capillary waves. Each of these could justifiably claim 
our attention. 

The tides, for instance, with their typical heights of 2-10 ft (up 
to 50 ft in extreme cases, as at the Bay of Fundy) and their clocklike 
regularity at most places, may someday be as important in power 
generation as they long have been in determining ship-arrival and 
departure times. 


Travel direction 


Time (hr) 


Fig. 2. Internal waves with varying 
heights and periods, generally 
moving at speeds less than 1 knot, 
form between subsurface water 
layers whose densities differ be- 
cause of differences in temperature 
and/or salinity. They are usually 
detected by oscillations in the 
depth of isotherms, as shown, as 
one water mass replaces another 
along an undulating boundary; but 
their presence at depth frequently 
can be inferred by “‘slicks" of 
smooth water visible at the sur- 
face, located above the trailing 
slope of larger internal waves. 


‘¢: INTERNATIONAL SCIENCE AND TECHNOLOGY, CONOVER—MAST PUBLICATIONS, INC., 1964 


10 


OCEAN WAVES 


S$ 

skate | Wave 

Code Herth & 
ft) 


YO SNS SE CS S 


9 orders of magnitude. 


Seiches and storm surges—generated either by hurricanes, tropical 
cyclones, or, in the right circumstances, by frontal squall lines—are 
also of more than passing practical interest. The heights of these 
sporadically occurring wind-driven waves can easily reach 10 ft or 
more in harbors; they differ from each other primarily in that the 
seiche is a storm surge which, because it occurs in a landlocked lake 
or partially inclosed harbor, enters into a standing-wave oscillation 
that persists after the generating wind dies down. The effects of 
both on coastal and harbor installations on occasion compare with 
those of the less frequent but more spectacular tsunamis, which are 
generated by some of the seismic disturbances that occur in ocean 
areas. 

Tsunamis are the most awesome waves on the surface of the sea. 
The modest 1-2 ft heights that characterize them in the open sea 
rapidly piles up to nearly vertical walls of onrushing water—as much 
as 100 ft high—along coast lines and beaches of appropriate config- 
uration near their area of generation, in the Kamchatka Peninsula, 
the Aleutian Islands, the Kuriles and the South Pacific. 

In the family of ocean waves the smallest are the capillary waves. 
They have sharp troughs that point downward into the water, in 
contrast to ordinary wind-driven waves which have sharp crests that 
point up into the air. This difference in form is a consequence of the 
capillary’s very short wavelengths; below wavelengths of about 
2.44 cm, waves on water show puzzling nonlinear properties, which 
are somehow related to the large local curvature of the water surface. 
Under these conditions the effect of water’s surface tension in 
controlling the wave’s form and height becomes more important than 
the factors of gravity and water depth that are the controlling 
parameters for other waves raised on the sea by winds. 

It’s these other wind waves whose wavelengths range up to 
thousands of feet, however, that make ships heave, pitch, roll, surge, 
sway and yaw that limit ship speed; and that routinely travel as 
“swell” thousands of miles out of the storm areas in which they are 
born, across the oceans, to break with mostly gentle but unending and 
deadly erosional efficiency on the shores. Let’s concentrate on them. 


Birth and development of wind waves 


If wind waves were perfectly periodic, simple harmonic progres- 
sive waves with infinitely long crests—as shown in the lower part of 
Fig. 3—or if this standard assumption of classical wave theory were 
even approximately true, they would have been understood for more 
thanacentury. But wind effects on the sea surface are not this simple, 
pecause turbulance and viscosity in both sea and air introduce com- 
plex nonlinear effects. 

Wind turbulance creates a moving pattern of minute fluctuations 
in air pressure over the water; these can generate the initial tiny 
ripples that eventually become fully developed waves. Viscosity and 
turbulence also create a distribution of pressure differences in the 
air that is out of phase with the waves, and these pressure differences 
feed in the energy needed to grow bigger waves. 


11 


Fig. 3. The infinitely complex, real sea surface is 
closely approximated in wave studies by a model 
surface which, as shown, is made up of a large 
number of randomly superimposed, simple harmonic, 
Progressive sine waves—each having its own amp- 
litude, direction of travel, and frequency. 


Measuring the amount of energy fed into waves by the wind is 
a severe and unsolved instrumentation problem. However, we can 
attain one important practical end—forecasting sea states—by 
treating the character of the sea surface statistically, after the energy 
being fed into the waves equals the energy dissipated by breaking at 
the wave crests, so the waves are no longer growing. This point of 
dynamic equilibrium—where the sea is said to be “fully developed”— 
limits the height wind waves can achieve, even under forcing 
conditions of strong winds in severe storm areas. Classical hydro- 
dynamic theory, although it cannot really explain this limiting process, 
nevertheless is useful in appreciating what seems to be going on 
physically. 
Wind waves limited by blowing their tops 


The ideally organized motion of water particles beneath a regular 
train of waves, moving in water deep enough so bottom effects don’t 
enter the picture, is shown in Fig. 4. Perhaps surprisingly, the water 
particles do not move en masse with the waves above them which 
carry the wind-supplied energy from one parcel of the ocean to 
another. It’s fortunate that they don’t. If you recall standing inshore 
of the breakers along a beach, where, after breaking, the water 
particles do move en masse, you'll realize instantly that no ship could 
sail if a 10-ft wave on the open sea, for example, represented a wall 
of water that high moving along with the waves. 

Instead of traveling with the waves, the particles move in nearly 
stationary circular orbits which lie in the vertical plane. Orbits of 
particles at the surface have a diameter equal to the height of the 
wave from crest to trough. Below the surface, orbits grow smaller 
with increasing depth, by a factor of about 1/2 for a depth equal to 
1/9th the wavelength, 1/4 for a depth equal to 2/9ths the wavelength, 
and soon. Water particle motion effectively is nil for all practical 
purposes, such as submarine operation, at a depth of about 1/2 wave- 
length. 


SCIENCE AND THE SEA 


All water particles in the long-crested deep-water waves of Fig. 4, 
whatever their depth and regardless of their orbital diameter, com- 
plete one orbit in the same period taken by the wave itself to advance 
one wavelength. But the particles don’t all reach the same points in 
their orbits—the top for instance—at the same instant. Rather, like 
the valves in an engine opening and closing at just the right instant 
in the combustion cycle, the water particles phase in and out of the 
appropriate positions in their respective orbits so as to fill the wave 
form as it progresses laterally. 


= = 


: Ti 
Water particles travel this way 


Wave form and particle distribution at one instant 
———— Wave form and particle distribution 1/ period later 


<— 1 —> 


> > 


120° 
ale 
a7 


Fig. 4. Instead of traveling with the waves, the water 
particles themselves move in nearly stationary orbits 
whose diameters decrease exponentiaily with depth 
beneath the surface. Each particle cycles into the 
appropriate position in its orbit so as to sustain the 
wave form as it progresses, carrying energy across 
the sea. 


The energy spectrum of the sea 


The ideal wave train pictured in Fig. 4 has infinitely long crests 
that are somewhat more narrow, and equally long troughs that are a 
bit wider than those of a sinusoidal wave; its form more nearly 
approaches the curve called a trochoid. And as wind-generated waves 
grow steeper their form departs even more from the sinusoidal ideal. 

No one has ever seen—and no one ever will see—a sea that be- 
haves in the classical way just outlined, not even for a finite time 
over a finite area of the ocean. Yet for many years attempts were 
made to force real waves to fit this restrictive oversimplified theo- 
retical model, at least locally. 

But actual waves on the surface of the sea are irregular, aperiodic, 
and short crested. The realization that the classical theoretical 
structure was untenable came gradually. Some features of real waves 
were discovered, written up in classified reports, and so successfully 
buried they had to be rediscovered by others several times before the 
knowledge became available to those studying ocean waves. 

The essential feature of wind waves, and of their swell progeny 
which usually have distinctive frequencies (see Fig. 5), is that in 
practice they must be studied in terms of probabilistic models and 
measured and analyzed by statistical techniques. To do this now- 
a-days, we use an extremely useful but still not fully accurate model 
of the waves that describes their fluctuation in height at any point 
in terms of a statstically invariant Gaussian (i.e., normally distributed) 
function of time. Such functions were studied originally in communi- 
cations theory to evaluate noise variation as a function of time. 

When the function that describes the fluctuating height of waves 
(the “noise’’) at a fixed point is generalized to cover many points 
over the sea surface, we obtain a function—a model of the sea 
surface—that closely approximates reality. This model sea surface 
is a characteristically short-crested, Gaussian surface that moves in a 
convincing way through time. 


SEA AND SWELL DIFFER CLEARLY...SOMETIMES 


Sea 


60 sec 


Intermediate 


Swell 


Fig. 5. Waves still in the area of 
the winds that generated them— 
“sea’'—are typically but not always 
higher, more sharply peaked, more 
disorderly, and shorter-period than 
waves—''swell’’—that have trav- 
eled out of their generating area. 


OCEAN WAVES 


Such a surface can be easily understood from Fig. 3. It’s made up 
of a large number of randomly superimposed, simple harmonic, pro- 
gressive sine waves of different amplitudes, each traveling in a 
different direction and each having a different frequency. 

Here’s another way to think about this all-important concept, 
let’s step back to the physical picture of waves for a moment. As 
the wind blows and as the waves grow, turbulent variations and 
varying amounts of internal eddy viscosity —as well as the interaction 
of one wave with another—set an individual limit to the growth of 
each individual component wave train in the developing sea. They 
do this by initiating the energy-dissipating, breaking, or “white-cap” 
process, whenever a momentarily high crest reaches an unstable con- 
figuration. (In the classical theory, this occurs when the height-to- 
length ratio of waves in a train reaches the critical value of 1/7th at 
which point in a wave’s development its crest is sharply peaked, as 
shown in the margin. But on the real ocean this limiting value is 
not known.) Thus, the total energy present in all of the waves ona 
developing sea progressively distributes itself over a range of fre- 
quencies, each frequency characterizing a particular wave train. As 
the waves continue to grow and as new trains continually develop, 
this range extends more and more to shorter frequency—or longer 
period—waves. In brief, a spectrum of ocean waves is formed (Fig. 
6), in which—for any given wind velocity and for fully developed 
waves—the energy distribution over the band of wave frequencies 
from 0.4 x 10-! to 3 eps is distinctive. 


Fig. 6. When wind-generated ocean waves reach 
maximum height their energy, which is proportional 
to their mean-square height, is distributed overa 
narrow frequency band that varies with the wind 
velocity, as shown. Such distinctive energy spectra 
underlie wave-forecasting systems. 


40 knots 


5 
AG 

24 
a 
=) 
vo 
i=] 
o 
o 

2 8 
= 

2 

1 

0 


0.10 


0.15 
Frequency (cps) 


13 


Spectral filters and wave forecasts 


This spectrum enables us to resolve the total variance of the mean- 
square sea-surface elevation (the “energy,” or total area under spec- 
tral curves such as in Fig. 6) into contributions traveling in different 
directions and having different frequencies. Or put another way, if 
the waves on the sea surface are put through a filter—either in re- 
cording or in subsequent analysis—so that only those waves traveling 
in a small range of directions and occupying a small band of 
frequencies are left on the model “sea surface,” we can specify this 
fraction or component of the variance. 

The problem of finding an adequate way to estimate the spectrum 
of a statistically invariant Gaussian process is not simple. And it 
arises in many fields besides ocean waves such as turbulence, seismic 
analysis, electronics, and weather prediction. Happily, it was solved 
in 1949, by John Tukey of Princeton. 

Once the problem was solved, we were able to develop ways to 
forecast swell quantitatively; we were able to analyze rather frag- 
mentary wave data and discover the many different spectra that 
occur in nature; and we could predict with some sophistication the 
effects of wave refraction in shallow water. 

The idea of spectral filtering just mentioned comes up in still 
another important way, in connection with operational wave-and-swell 
forecasting. About 10 years ago, for example, Gerhard Neumann of 
New York University found it was possible to derive a theoretical 
expression for the characteristic frequency spectrum of wind waves 
from thousands of visual wave observations made with a stop watch. 
This theoretical spectral equation gave no information about different 
directions of wave travel. It depended on only two variables: (1) the 
wind velocity; and (2) either the distance over water that the wind 
blew with constant velocity and direction, also called the “fetch,” or 
the duration of the wind. And it provided a moderately accurate way 
to forecast the spectrum of waves in deep water as a function of the 
past history of the weather over the ocean. Fig. 7 summarizes some 
of the salient features of this prediction system. It forecasts—among 
other things—the average of the heights of the one-third- highest 
waves that will be running, and an average wave period. 


Height of 14 highest waves (ft) 


08 6 7 3 oO 20 25 
Predominant wave period (sec) 


15 


Fig. 7. Salient features of the wave forecasting system 
in current use by the U.S. Navy are shown on this 
diagram. Forecast is a function of the weather over 
the ocean and depends on only two variables—wind 
velocity, and either the fetch or the duration of the 
wind. Intersection of either of the latter curves with 
the appropriate wind velocity curve yields forecast 


SCIENCE AND THE SEA 


Swell, on the other hand could only be forecast in this scheme by 
means of mathematical filters. These slowly tuned through the 
spectrum of the wind-born sea as a function of the dimensions of the 
storm source, the strength of the winds in the source, and the distance 
from the source of the point for which the swell forecast was to be 
made. 

These approaches to forecasting waves and swell were built into 
an operational forecasting system—by Neumann, R. W. James, and 
me—that is in current use by the US Navy and most other maritime 
agencies. 

In the effort to develop better ways to predict waves and swell 
many different spectral forms and other procedures have been pro- 
posed. Large areas of disagreement developed among oceanographers 
concerning the precise form of the wave spectrum of a “fully de- 
veloped” sea for a particular wind speed. But more recent data 
appear to be resolving these disagreements. Improved calibration of 
wave-recording instruments—of all things—has brought the formerly 
widely divergent results of different investigators into closer agree- 
ment. And formerly overlooked considerations of how the wind speed 
varies with height seem to account for most remaining discrepancies. 
The forecasting rules developed by Neumann, James, and myself will 
have to be corrected in the light of recent results. But they were 
surprisingly close to reality in most respects, especially considering 
how “primitive” the hand-held stop-watch data were, upon which 
they were based. 


Lots of new ways to measure waves 


Study of wave spectra for all purposes will be helped a good 
deal by more measurements, of higher accuracy, of real waves in the 
ocean. In general, waves are recorded on graphs like those of Fig. 5, 
which show the varying height of the water surface at a fixed point 
as a function of time; needed analyses are performed later. Such 
records ignore the sometimes significant question of which way the 
waves travel, but there are a few recently developed approaches to 
making this difficult measurement that we’ll mention below. 

Wave measurement is simpler near the shore in shallow water 
where suitable structures, or the bottom, are available for anchoring 
instruments. On the open sea of course there is no fixed frame of 
reference to which a wave recorder can be fastened. It was so very 
difficult to get time histories of waves under open-sea conditions, in 
fact, that an instrumental way to measure waves from a ship was 
developed only a decade ago, at Great Britain’s National Institute of 
Oceanography (NIO). This method, diagrammed below, right , uses 
two identical instruments mounted on opposite sides of the ship, and 
their outputs are averaged to compensate for differences in wave 
height on either side. Each instrument consists of a pressure sensor 
and a vertical accelerometer. In principle, the pressure is a measure 
of water height above the instrument, and the doubly integrated 
accelerometer value yields displacement of the instrument above some 
chosen reference level; the sum of the two in the form of a voltage 
is the wave record. With this instrument, storm waves and swells on 
the open sea in all of their rampant variety have finally been meas- 
ured accurately, and although it has only been used for a relatively 
short time on British weather ships the data gained have been of 
exceptional value. Recorders using essentially the same principle 
may soon be installed on all US Coast Guard weather ships. The NIO 
instrument is already on the Atlantis II research vessel of the Woods 
Hole Oceanographic Institution. 


H - Herqht 
V- Vertical 
Displacement 


W—Wave recorders 


Reference Level 


Ship -borne 
Wave Recorder 


14 


Other methods for measuring waves at sea do not use a ship’s hull 
as an anchor and reference point—instead they use as a reference 
the quiet water that lies below the depths agitated by waves. One 
such method suspends from a buoy, a large flat plate (or “drogue”) 
that is designed to respond to the passage of the waves with as little 
lift as possible. To the buoy is attached a measuring pole (see 
marginal sketch) against which wave fluctuations are recorded either 
mechanically or electrically. Such methods are generally unsatisfac- 
tory and quite costly. 


Direction of 
<< wind 


Floatin 
buoy 3 


Pole and Droque 
tyre Wave Recorder 


Gone surfaces of 
equal pressure) 


The problem of high cost in obtaining large numbers of nondirec- 
tional wave records may be eased by a floating-buoy device—dubbed 
the “Splashnik” —recently developed at the David Taylor Model Basin 
in Washington, D.C. Said to cost about $150, the device converts the 
output of a vertical accelerometer mounted on a raft, with a trans- 
mitter, to an FM signal whose frequency varies with acceleration; it 
transmits the signal to a nearby ship where the familiar double inte- 
gration to get wave height is performed. 

Another new and promising way to measure waves on the deep 
sea is to use a highly stable platform, like the Scripps Institution of 
Oceanography’s new “ship-on-end”—dubbed FLIP. Any wave re- 
cording device would work well on FLIP. In recent trials in waves 
40 ft high, FLIP moved a remarkably small 6 in.! Anyone who's 
spent any time at sea will appreciate what this means. 

Nondirectional devices on stable platforms like this could be used 
in suitably spaced arrays to yield useful data about wave directions, 
if such platforms cost less. Using wave recorders in this way would 
be similar in principle to using antenna arrays for direction-finding 
in radio astronomy. 

Waves on the open sea with lengths shorter than one thousand 
feet or so also can be measured by stereophotogrammetry. Witha 
long ship and cameras pointed horizontally at each end, the profiles 
of several waves can be measured. Aircraft can also obtain stereo- 
wave photographs, and these can be used—though at the cost of much 
time in stereoanalysis and computation—to get the directional wave 
spectrum. 

A more direct approach to getting directional information on 
waves in a wind sea, developed at the British NIO, uses a single float- 
ing buoy (Fig. 8) that’s kept in constant alignment with the wind by 
means of an attached pellet and drogue, as sketched in the margin. 
Inside the buoy are an accelerometer and two gyroscopes and 
associated electronics. The assemblage gives data on pitch, roll, and 
heave (or vertical displacement) of the buoy, from which some 
features of the angular (azimuthal) distribution of energy in each 
frequency band of the wave spectrum can be derived. 

Regardless of the direction taken by waves and swell on the open 
sea, their ultimate fate is certain. Sooner or later either they die at 
sea, as the poorly understood processes which dissipate their energy 
operate to destroy them, or they reach one of the world’s coastlines. 
There, frequently, they expend their energy in one last sometimes 
destructive burst before they die. 


OCEAN WAVES 


Fig. 8. British National Institute of Oceanography developed this 
floating buoy that carries an accelerometer and two gyroscopes. 
Instruments give data on pitch, roll, and vertical displacement of 
buoy, from which directional wave spectra can be derived. 


To all things there comes a time 

As wind waves and swell finally approach a coast and the depth 
of water decreases, the water particles in orbital motion far beneath 
the waves begin to “feel bottom.” Orbits closer to the bottom of the 
wave structure gradually flatten into ellipses, and the forward-back- 


150 


120 90 60 


Water depth contours (ft) 
=== Rays for 7-sec period waves 


=—=<==""Rays for 14-sec period waves 


Fig. 9. Differences in water depth along a coast cause waves to 

refract, as shown here by rays showing direction that waves travel 

Lower frequency waves such as swell refract more than the waves 

of higher frequency, complicating the picture of how energy is dis- 
tributed along coast. 


15 


ward motion of particles becomes greater than the wave’s height at 
the surface. As these changes occur along a gently shoaling bottom, 
both the group and the phase velocity of the waves decrease. Waves 
in shallower water are more retarded than the waves just behind 
them that are still in somewhat deeper water; as a consequence 
wavelengths also decrease, but wave periods remain the same. 
Differences in depth along the coast account for differences in the 
amount of retardation experienced by a wave along its length. This 
in turn causes the waves to refract as they approach the shore—waves 
of lower frequency, such as swell, refracting more than waves of 
higher frequency—as shown in Fig. 9. 

Like the frequency or period, the all-important amount of energy 
being transported shoreward by the waves at all stages of their prog- 
ress also remains approximately constant. To conserve energy as 
their velocities decrease, the waves must grow higher and steeper— 
until turbulence in the surf and the final plunge up the beach dissipate 
the energy completely. This is the energy that coastal engineers must 
contend with. 

Just how much of the wave energy in deep water is ultimately 
destroyed by breaking at a beach, how much by whitecaps and turbu- 
lence in deep water, and how much by friction against the bottom in 
shallow water is not known. Barber and Tucker of NIO estimate, 
however, that a run-of-the-mill ocean swell—perhaps 2 m high in deep 
water—contains 5 x 10®ergs of energy per cm2of sea surface. If the 
period of this swell is 10 sec, its group velocity in deep water is about 
7.8 m/sec, which means that the swell is transmitting energy at the 
rate of 3.9 x 10%ergs/sec for each cm of length along the crest. When 
this swell reaches a coast this energy is nearly all spent in turbulence 
in the surf or breaker zone. It amounts to approximately 40 kw along 
every meter of shoreline. And how many meters are there along the 
shorelines of the world? 


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SURVIVAL at SEA 


356-697 O- 69-3 


SCIENCE AND THE SEA 


By John W. Chanslor 
Maritime Safety Division 
U.S. Naval Oceanographic Office 


The powerful and unrelenting sea, though peaceful at times, is 
the inevitable enemy of all who venture upon it. It follows, then, that 
those who “go down to the sea in ships” and have accepted this calling 
should undertake sufficient survival study to assure that what was 
once their home will not become their coffin. 

Survival in the sea depends upon four things: knowledge, equip- 
ment available, self control, and training. Without these four 
prerequisites, one's chance of survival at sea would depend on the 
severity of the situation. Many mariners have been lost at sea 
simply because they lacked sufficient training to know how to survive. 

It is the intent of this article to bring to the fore again, a few of 
the basic principles of survival. 


PRE-ABANDONMENT 


In peacetime abandonment at sea is rare. Consequently, few 
mariners today have been through this experience. Shifting cargo, 
hull damage, machinery casualties, collisions, fire, and groundings, 
however, are rather common. When any of these occur, abandon- 
ment may be the ultimate consequence. 

The order to abandon ship is an irrevocable decision, made 
usually under conditions of uncertainty, where all action directed 
toward saving the ship ceases. The success of abandonment is 
highly dependent upon the point in time when it is actually begun. 

Instances have been reported of premature abandonment. As 
an example, one of these involved a Liberty ship which developed 
cracks in the main deck during a North Atlantic gale. The ship 
was hove to in order to ease the strain of pitching and rolling. She 
remained in this condition for nearly three days. The weather 
moderated on the third day and the ship proceeded to the nearest 
port. On the fourth day a weather report, indicating further heavy 
gales, was received and the Master decided to abandon ship. The 
entire crew was rescued within a short period of time after aban- 
donment. The ship remained afloat and finally beached itself on 
one of the Hebrides Islands. Although not conclusive, the circum- 
stances tend to suggest that the Master, in all probability, could 
have reached port safely. 


ABANDONING SHIP 


As with most problems, there is a proper way in which one 
should endeavor to abandon ship. The span of time between the 
Commanding Officer’s decision to abandon ship and the actual time 
of departure is a most important one. In addition, it is also a 
period of possible confusion and mental strain. If the time element 
is sufficient, certain preparations can be made before the actual 
time of abandonment. Of course, this would include having the 
radio operator send out the required distress message. If a reply 
is received, the fact should be made known to each boat and raft. 
A final check on the position of the ship together with the range 
and bearing to nearest land is vital information each life craft 
should have. Other items such as a pilot chart, navigational chart, 
sextant, chronometer, radio, plotting equipment, almanac, compass, 
flash light, and navigational tables should be placed in some of 
the life craft. 

Reaching an exposed deck is frequently difficult. Survivors of 
sinkings have reported that some of their shipmates went down with 
the ship because of the confusion attending the disaster. In many 
instances, the compartments in which the men were trapped were 
not actually cut off completely, only partially. These lives were 
lost due to the development of habit and lack of foresight. 

When a man reports on board a new ship he usually learns the 
easiest way from his bunk to his duty station and automatically 
uses it in both directions, watch after watch. Thus, the habit of 
using the same route day after day becomes so strong that in time 
of emergency he finds it difficult, if not impossible, to utilize an 
alternate avenue of escape. A collision or explosion may flood a 
compartment through which the usual route passes, or knock out 
a ladder that is customarily used. Every mariner should, therefore, 
thoroughly know his ship. This familiarity can best be accomplished 
by drills held at different times of the day and night. Those who 
know all escape routes have an advantage that may mean the 
difference between being trapped in a sinking vessel or getting away. 


18 


Topsides training in the methods of abandoning ship can be 
given in conjunction with these drills. The following points should 
be frequently stressed: 


1. Whenever possible, men should abandon ship fully clothed but 
without shoes. This principle applies equally well for any 
latitude. 

2. When habitually used passageways and hatches are blocked or 
cut off, individuals who know all escape routes have a far 
better chance of reaching an exposed deck. 

3. If there is a choice, men should leave by the windward side of 
a sinking vessel, and from either the bow or stern, whichever 
is lowest in the water. 

4. If the ship is listing, men should leave by the side lowest in 
the water. 

5. Jumping from the deck of a sinking ship with a high freeboard 
introduces difficulties which do not appear when men abandon 
ship by means of a ladder, cargo net, or line, etc. If at all 
possible, men should leave by climbing down rather than 
jumping over the side. The chance of landing on debris is 
great. 

6. If one must jump, he should do so feet first, with the legs 
together, the body erect, and life preserver securely fastened. 

7. When jumping from a ship that is entirely surrounded by 
burning oil, it is best to jump to windward, feet first. Grab 
the nose and cover the mouth with one hand and cover the 
eyes with the other. A very deep breath should be taken 
prior to the jump. The inherently buoyant life preserver and 
shoes should be discarded. The COg inflatable preserver 
should be kept on, but uninflated. Clothing should be worn, 
however, as a protection against flames and debris. The 
survivor should swim as long as he can under the surface of 
the water. When it is necessary to come up for another 
breath, the swimmer should look up, extend his arms above 
his head and pull them in a wide vigorous sweep which will 
aid him in coming to the surface. His hands and arms then 
should make wide sweeping movements across the surface to 
splash the water, thus driving away the flames momentarily, 
forcing the upper part of the body above the surface and 
allowing the man time to breathe. As he comes to the surface, 
he should endeavor to turn his back to the wind before the 
next breath is taken. After the breath is taken, he submerges 
again, feet first (Standing Dive). This technique should be 
repeated until he is clear of the burning oil. 

8. When a man reaches the water after abandoning ship, he 
should attempt to get away from the ship by swimming his 
fastest and most powerful stroke. He should put from 150 to 
200 yards between himself and the ship before he stops to rest. 

9. In time of war or national emergency, the following lesson 
may be well to remember. On many occasions during World 
War II, the enemy strafed survivors from sinkings. In this 
manner many men lost their lives not knowing that six to ten 
feet of water would have saved them. This depth of water 
will not stop the bullets, but it will deflect them away, giving 
the survivor another chance. Five seconds is about the max- 
imum length of time a modern aircraft can hold a small traget 
in his gunsights. Conversely, it is rather easy for a swimmer 
to hold his breath for 15 seconds. 


After a group of survivors have successfully reached the water, 
their chances for eventual rescue will be improved greatly if a basic 
pattern of behavior is followed. These elements are: 


1. When a man has reached a point between 150 and 200 yards 
from his ship, he then should start making his way to one of 
the life craft. 

2. He should conserve as much energy as safely possible, as an 
unforseen emergency may arise calling for a large expenditure. 

3. If explosions are occurring, a survivor should swim on his 
back with head and chest as far out of the water as possible. 

4. A survivor should remember that team work is required for 
successful recovery and that his shipmates are not opponents 
in this struggle. 

5. For the maximum number to survive, a group of survivors 
should establish a definite chain of command. A capable 
leader is a prerequisite for high morale. He will see that 
available supplies are properly cared for, that lookout duties 


SURVIVAL AT SEA 


are assigned, and that signaling gear is available and 
properly used. 

6. Life craft should be lashed together so that the group will 
not scatter. 


Once a crew has completed abandonment and is distributed 
among the life craft, under most conditions, rescue is reasonably 
certain. Research shows that due to the close teamwork between 
rescue commands, ships, and planes most survivors are picked up 
quite swiftly—many times within only a few hours. 


USE OF CLOTHING AS A FLOATING AID 


The most important piece of abandon ship equipment is the life 
preserver. When properly adjusted, it will support a man even 
though he is unconscious. A survivor should not abandon hope, 
however, if he finds himself in the sea without one. For, one may 
be improvised from the very clothing he is wearing. 

To inflate a shirt or jumper, all buttons should be buttoned and 
knots tied in the collar and cuffs. The shirt tails should be tied 
around the waist. When this has been accomplished take a deep 
breath of air, submerge, and expel the breath into the shirt between 
the second and third button holes. Properly inflated one’s shirt 
becomes a good floating aid. 

Trousers, though, will make an even better buoy than the shirt 
or jumper. After the trousers have been removed, tie a single over- 
hand knot as close to the end of each leg as possible and secure the 
fly. Then take one side of the waist in each hand and bring them 
up and over the head from behind the body. This traps a good 
pocket of air in each leg. To completely fill the trousers with air, 


submerge and blow air in the opening. The waist is then gathered 
together in one hand, resulting in a good pair of water wings. 

Thus, a survivor should never discard his clothing, for in addition 
to a floating aid, it can be very useful in other ways. It will serve 
as his protection against sunburn, windburn, cold, and of course, 
be needed upon rescue. 


SWIMMING 


An unexpected ship roll coupled with a second of carelessness, 
together with a slick deck, and a mariner is very likely to cease 
standing and start swimming. 

The first act of survival, a man overboard should concern 
himself with,is to immediately endeavor to swim away from the 
ship’s screws. Although an alert Watch Officer will swing the 
stern of his ship away from a man overboard, he may be completely 
unaware of the situation at the time. Momentum, luckily, is in one’s 
favor if he falls overboard, as it will usually carry him within a short 
distance of the safety zone from the propellers. His first sprint, 
then, will be but a short one. 

After a man is safely clear of the propellers and his ship has 
passed him by, he should conserve his energy. Unless a life ring or 
buoy is seen in the near proximity, he should just float. If he is not 
wearing a life preserver an improvised one from his clothing, as 
previously mentioned, should suffice until recovery. 

One of the latest methods recommended for endurance is the 
“Jellyfish Float.” It has been designed to sustain a person who 
finds himself in the water without any floating aid. The physical 
attitude assumed actually has some resemblance to that of a jellyfish. 
Its success depends on the person’s ability to control his breathing. 

To assume the Jellyfish Float position, slide the arms down along 
the legs until they are suspended toward the bottom. Do not bend 
the knees, but let the legs hang freely and relaxed. Take a deep 
breath and allow your face to submerge below the surface. Remain 
in this relaxed position until another breath is required. 


19 


When more air is needed, just move the hands up and forward 
below the water surface. Then press the hands down and back (as 
in a Butterfly Breast Stroke), exhaling. During the stroke lift and 
turn the head to one side. Upon reaching the surface, inhale 
through the mouth. 

If a swimmer takes a deep breath, he will float at the surface 
in this manner. However, should he drop too deep on returning to 
the floating position, a scissors or flutter kick will return him to 
the surface. 

Unless one is seen going overboard, or unless he is shortly 
missed, another facet of survival appears, i.e., immersion hypo- 
thermia—the term for subnormal body temperature resulting from 
the loss of heat when a human is immersed in cold water. 

Body temperature control depends upon the balance one’s body 
is able to maintain between heat loss and heat production. 
Production of heat is accomplished by the conversion of food 
to energy. The principal conductor of heat throughout the human 
body is blood. And, primary heat loss is at the skin surface. If the 
vital organs do not maintain their heat, they will cease to function. 
During the process of slow body cooling, the amount of blood in the 
vessels of the extremities is gradually reduced and circulation is 
slowed. As body cooling is increased, circulation slowly ceases in 
the hands and feet. Eventually, the heat produced by the internal 
organs is not sufficient to maintain required temperature and death 
occurs. 

The following estimate of survival from immersion hypothermia 
is based upon the temperature of the water and the length of time 
exposed. It is believed to be approximately correct, but considerable 
deviations should be expected among individuals. Some men have 
lived in cold water many hours longer than the indicated figures. 
Thus, a search for survivors should not be called off because the 
table shows they may have succumbed. 


Water Temperature Duration at Survival 


CF.) (°C.) 
32 te) Less than one hour 
40 4 Y% to 3 hours 
50 10 1 to 6 hours 
60 16 2 to 24 hours 
70 21 3 to 40 hours 
80 27 indefinite 


Survivors whose body temperature have been lowered to levels 
which can be fatal should be rewarmed rapidly. The proper methods 
of treatment will be found in medical and survival books carried 
aboard most ships. Basically, treatment consists of the following: 


The survivor should be undressed immediately and placed in a 
hot bath of about 120°F. for 10 minutes. Although this may be 
painful to him if he is conscious, it is the reeommended method to 
insure survival. After the bath, the survivor should be dried with 
a towel and placed in warm blankets. If his temperature does not 
rise, he should again be placed in a hot bath until his temperature 
reaches 98°F. At this point, his temperature should continue to 
rise and a more gradual rewarming is suggested. 

If a shower must be used in lieu of a bath, the survivor should 
be wrapped in towels, keeping them thoroughly saturated with water 
between 120° to 125°F. 

Survivors who are conscious when rescued from cold water will 
often survive without the aid of a warm bath if they are dried and 
placed in warm blankets. Massaging is to be avoided under all 
conditions. 

LIFE CRAFT AND SURVIVAL 

After a survivor has reached one of his ship’s life craft, he is 
almost assured of survival and rescue. Lifeboats and rafts of the 
Navy, Merchant Marine, and Coast Guard have been adequately 
supplied with sufficient survival equipment to cope with emergencies 
at sea. All one normally must do is to learn what this equipment 
is and how to properly use it. Of course, this should be done long 
before an emergency arises. 


SCIENCE AND THE SEA 


Assuming that the emergency message was properly sent by 
your ship prior to abandonment, help from one of our many Rescue 
Coordination Centers should be on the way by the time you reach 
one of the life craft. Rescue Coordination Centers, operated by the 
Navy, Air Force, and Coast Guard, are always on the ready. Upon 
the receipt of an SOS or Mayday, they immediately begin to effect 
assistance and recovery. 

Thus, one’s stay in a life craft will ordinarily be but a short one. 
However, if the SOS was not sent for some reason, or if the position 
in it was in error, then a prolonged stay in your lifeboat or liferaft 
may be required. Under these conditions survival is still likely. 

Command aboard a life craft is assigned by the Commanding 
Officer of the ship. If the assigned life craft commander is not 
present, the next senior should then assume command. His responsi- 
bilities are great, for chance of survival is greatly enhanced by his 
ability to assume responsibility, maintain morale, enforce discipline, 
assign jobs, take charge of rations, and deal with emergencies. 

Generally, it is best to remain near the position of abandonment 
until reasonable hope of rescue craft arrival has to be abandoned. 
The sea anchor should be rigged, put into use immediately, and left 
out for two or three days. 

When departure from the scene is decided upon, the course set 
should be in accordance with the prevailing winds and currents 
shown on the Pilot Chart. It is rather useless and disheartening to 
attempt to sail or row any great distance against contrary winds 
and currents. 

During times of weather too heavy in which to safely sail, the 
sea anchor should again be put into use. When this is necessary, 
remember that it should always be veered to lie in a trough when 
the life craft is at the wave crest. The length of line to the sea 
anchor should not coincide with the length of the sea, or the boat 
and sea anchor will both be in wave crests at the same time and 
the drag effect will be lost just when it is needed most. As the boat 
will be making some sternway, the rudder should be unshipped to 
prevent damage. If it is possible to rig a small sail fore and aft 
it will act as a weather vane and tend to keep the boat’s head into the 
wind and sea. When, for any reason, this isn’t possible, one set of 
oars should be manned in readiness to keep the boat headed into the 
approaching sea. 

When rescue becomes a possibility and a ship or aircraft is seen 
by the lookout, the signaling equipment becomes an all-important 
item. 

It is most difficult to spot life craft from an aircraft above 
3,000 feet. If a sea is running, it is also quite difficult to see life 
craft from a surface ship. 

Experience has shown that the signaling mirror is a very effec- 
tive signaling device. It takes considerable concentration to use it 
properly, but the small pocket-size mirror is capable of reflecting 
sunlight so that it can be observed from a distance of 8 to 10 miles. 
The mirror is tricky to use; but if instructions accompanying it are 
closely followed, it should not be too difficult. Signals should be 
continued until it is positive the rescue craft can not lose sight of 
you. Ina liferaft with a sea running, this literally means on top 
of you. If rescue is to be made by aircraft, however, be careful not 
to flash the mirror in the pilot’s eyes—especially when he is making 
a landing approach. Pyrotechnic signals should probably not be 
used until rescue craft are actually seen. For, beyond 2 to 4 miles 
they are not likely to be observed. 


The most commonly used night signal is the flashlight. This is 
a very effective device and a waterproof model is standard equip- 
ment in nearly all life craft. The only note of caution here is to 
conserve the batteries as much as possible, using it only when 
really necessary. 

The dye marker is a good aid to discovery during daylight. It 
consists of a can of fluorescein dye powder, the contents of which 
are sprinkled on the water surface. The yellow-green dye should 
be visible from the air for a period of 4 hours at a distance of 10 
miles, at an altitude of 3,000 feet. Rough seas will shorten its 
longevity, however. 


Another very useful item in a life craft is the tarpaulin. A 
brightly colored one may be used to attract attention. It is alsoa 
survivor's best aid in collecting water. 

In tropical waters one’s greatest hazard from exposure is 
dehydration. This is usually the principal cause of exhaustion and 
death of those adrift in life craft. Under favorable conditions a man 
can survive without water from 8 to 10 days, on the average. With- 
out food, but supplied with adequate water, he may live for 30 days 
or more. Thus, when the water supply is limited, available water 
should be used efficiently. Dampen your clothes with sea water 
during the hottest hours of the day. Keep exertion to a minimum 
and sleep when possible. If you have no water you should not eat, 
as the amount of food the body can assimilate depends upon the 
amount of water available. This is one of the reasons emergency 
rations are purposely made bland. Others are that well-seasoned 
foods induce thirst and highly palatable ones, under extreme con- 
ditions, may make rationing difficult. Life craft rations are a 
compromise between an adequate diet and a limited supply of water, 
being high in carbohydrates and low in proteins, thus yielding 
maximum calories with a minimum demand on the kidneys. 

Water will be your most important need. When it is in short 
supply and cannot be replaced by chemical or mechanical means, 
but only by chance rain, use it efficiently. Men on short water 
rations during an extended survival period have usually experimented 
with some substitute for water; i.e., the drinking of sea water in 
moderate quantities, juice expressed from the flesh of fish, etc. 
However, the fact still remains that under survival conditions at 
sea, unless means for chemically or physically separating the salts 
from sea water are available, the only safe fluid to drink is rain. 
For, sea water is inimical to the human body and will shorten rather 
than prolong survival time. It aggravates thirst and increases water 
loss by drawing body fluids from the kidneys and intestines, 
resulting eventually in serious convulsions and delirium. 

As previously mentioned, the tarpaulin, sail, or poncho will be a 
great aid in collecting rain water. Plans for its exact use should 
be made in advance, keeping in mind that these sheets may be 
difficult to handle in the high winds and rough seas that accompany 
a squall. Watch the clouds and be ready for any chance shower. 
If the paulin is encrusted with dried salt, wash it in sea water. If 
the shower appears to be a light one, every available drop should 
be collected by first wetting the canvas with sea water, so that 
fresh water will not be absorbed by the fabric. The amount of salt 
water contaminating the rain water will be negligible, but the 
amount of fresh water lost through absorption, if the cloth is not 
first wet, will be considerable. In a driving rain, water can be 
collected by holding a canvas or any flat surface at an angle. 

Store rain water in any available receptacle; even the bladders 
of inflatable life jackets have been successfully used. The human 
body can store water very well and, therefore, one should drink all 
he can when water is plentiful. Little of the water taken in 
quantity when one is dehydrated is lost through perspiration or 
excessive urination. Rain water, however, does not always satisfy 
the thirst as it lacks minerals and is tasteless. It has been recom- 
mended it be mixed with a little sea water, coffee, or tea solubles; 
or that some of the hard candy from the emergency food kit be 
dissolved in it for taste. 


FOOD 


If fresh water is available to the survivor, there is little cause 
for him to starve. One pound of body fat will provide your system 
with an equivalent of two good meals. The rate at which body fat 
ean be converted to heat and energy is dependent upon air temper- 
ature, physical activity, and mental state. It follows then that 
longevity can be extended by relaxing mind and body, and reducing 
exposure to extreme temperature. 


SURVIVAL AT SEA 


In addition to this stored energy, food may be gleaned from the: 


inexhaustible sea. For, desolate though it may seem, the sea is far 
richer in various types of food than an equal amount of land. Small 
fish will usually gather in the shadow of life craft. These should 
first be caught for bait. Or, clumps of seaweed will usually yield 
small crabs and shrimp. In using a dip net to catch bait, hold it 
under the water and scoop upward. If a fishing kit is not available, 
hooks can be improvised from insignia pins, pencil clips, shoe nails, 
fish or bird bones, pocket knives, or pieces of wood. Line may be 
obtained from shoe laces, shroud lines, or thread from clothing. A 
fishing line with a breaking strength of over 100 pounds can be made 
by utilizing a yard length of canvas ravelings. The canvas should 
be dry, as wet canvas is quite difficult to unravel. With 8 or 10 
strands held between the thumb and forefinger of each hand, twist 
the strands clockwise, while passing the right hand around the left 
in a counter-clockwise movement. This will form a section of the 
fishing cord. When approximately 18 inches of cord have been 
completed, cut off the strands at two-inch intervals, feeding ina 
new strand each time an end is reached. Continue this process 
until about 50 feet of cord is complete. 

Various sizes of cord may be made in this manner. A line of 
two strands will have a breaking strength of approximately 20 
pounds. 

A spear may be made by lashing a knife to an oar. As light is 
known to attract fish at night, shine the flashlight on the water. 
Or, use the signaling mirror to reflect moonlight on the water. 
While actually fishing, do not make the line fast to the life craft or 
person, as large or dangerous fish can pull one overboard or upset 
a raft. Captured fish and/or bright objects should not be left 
dangling over the side for similar reasons. 

Water fowl have been a source of food for many survivors. 
Several have reported them as having a musty odor and fishy flavor. 
All sea birds are edible and nourishing, however. They are appar- 
ently drawn to rafts and boats out of curiosity, by the small fish 
attracted by the life craft, but mostly because they afford a place 
to perch. Some survival reports mention the tendency of sea birds 
to roost on the life craft during the early morning and late 
evening hours. 

If activity in the life craft is restricted, sea birds apparently 
have little fear of man and will land on or near more frequently. 
After they have landed, wait until the wings are folded before 
trying to grab them. If they tend to shy away, they may be caught 
in the following manner: Make one end of a line fast to the craft. 
Tie a simple overhand knot in the bight of the line. Place some bait 
within the knot loop and pull the bitter end of the line when the 
bird is standing within the loop. Sea birds can also be caught by 
trolling a baited fishhook or baited toggle of metal or wood. In 
many cases, the ease with which they have frequently been caught 
has resulted in their being a more dependable source of food than fish. 

In addition to food, birds can be very useful to survivors in 
other ways. A streamer or fly can be made with the feathers. They 
may be skinned (cutting down the back) and a cap, ear muffs, scarf, 
or shoe lining fashioned from the downy breast feathers. Fishing 
spinners can be made from the long bill plates, and even the bones 
can be utilized for making fishhooks and skewers. 


INDICATIONS OF LAND 


A lookout should carefully watch for signs of land. Fixed 
cumulus clouds in an otherwise clear sky, or in a sky where the other 
clouds are moving, usually indicates land beyond the horizon. This 
type of cloud will form over high or mountainous land. Smaller 
clouds may hang, a little to the lee side, of atolls and small islands. 
On the under side of these, “lagoon glare’”’ may often be seen. This 
greenish tint is caused by the reflection of sunlight from the shal- 
low water of a lagoon, or of coral reefs. Actually, the reflection 
of light from any surface such as shallow water, sand, snow, or ice 
may be reflected in the sky or on clouds and is an indication of land. 

The flight line of birds is another good indication of land. 
During the day, they are in search of food and their direction of 
flight is meaningless. However, as most sea birds roost ashore, 
their evening and morning flights to and from their roosts are an 
excellent indication. 

During times of restricted visibility, there are still other indi- 
cations one should keep in mind. These are the odors and sounds 
of the shore. The odor of burning wood is known to carry a great 
distance. Mud flats and the musty smell of mangrove swamps may 


be similarly noticed. Normally, the sound of surf is heard long 
before it can be seen. Continued bird cries from one direction may 
indicate their roosting place. 

Long before Captain Cook visited the Pacific Islands, Polynesian 
navigators found their way home by watching wave forms ora 
certain joining of the waves. 

Consecutive swells travel parallel to each other, with the pre- 
vailing wind, until they reach an island and then bend around it. 
These swells, their distortion, and the resulting refraction, form the 
wave patterns utilized as a navigational aid. (Figure 1). 


Figure 1 


Suppose a survivor notices a wave pattern similar to that shown 
in quadrant III. That is, with the reflected waves coming back 
against the main swell. Land will then be in the general direction 
from which the reflected waves are coming. Consequently, one 
should head in this general direction, keeping a lookout for the 
choppy interference lines that form about 90° apart with the island 
at the apex. When this line is seen change course to sail parallel 
to it in order to reach the island. 

On the other hand, if a wave pattern similar to that shown in 
quadrant I is noticed, land is in the direction from which the waves 
are coming. Similarly, as in quadrant III, a survivor should sail in 
this general direction, keeping a lookout for the choppy line previ- 
ously mentioned and follow it to land. 

Quadrants II and IV are most difficult to recognize. About 
the only way one can detect these two sections is that the swells 
will not be perpendicular to the direction of the prevailing wind. 
This condition is noticeable, however. When it is detected, sail 
approximately parallel to the swell until the choppy intersection 
lines are seen and then follow them to land. 

Navigation has been a well-developed art in Micronesia since 
early times, with this type of wave pattern navigation forming a 
major part. 


RESCUE TIPS 


SURVIVORS 


Ze 


Weather on the quarter; survivors on the lee bow 


Figure 2 


SCIENCE AND THE SEA 


In peacetime, with a calm sea, a rescuing ship has few problems 
in recovering survivors. One merely lowers away the ship’s small 
boat, scoops the survivors from the sea and into the boat, then hoists 
the boat along with any survivors too weak to climb back aboard 
the ship. Unfortunately, the years of world peace are too few. 
And, wind and sea conditions conducive to small boat launching are 
not encountered with the frequency often desired. Thus, getting 
a survivor aboard ship can, at times, be quite difficult. 

There is no single method or official doctrine applicable for 
approaching survivors under all conditions. Here the judgement 
and knowledge of the captain must be relied upon. A proven tech- 
nique for recovering swimmers and men in life preservers, often 
considered as standard procedure, follows: The rescuing ship is 
positioned slightly up-wind from the survivors and allowed to drift, 
with engines stopped, down to them. (Figure 2.) In heavy seas, the 
weather should be kept on the quarter and the survivors on the lee 
bow. This practice reduces rolling, thus decreasing danger to the 
survivors as well as the rescuing personnel. If, however, a lifeboat 
or raft is to be approached, they will drift faster than the ship and 
the ship must, therefore, be positioned down-wind, letting the raft 
or boat drift down upon her. This method has the advantage of 
bringing the survivors to the ship. But, it also has various hazards 
and disadvantages. In heavy seas, the ship will be rolling and 
survivors must be taken aboard quickly. Additional care must be 
taken to assure against capsizing lifeboats and crushing personnel 
against the side of the rolling ship. 

Another successful method is for the ship to steam past the 
survivors with a small amount of way on. As the vessel passes 
them a heaving line with a ring buoy attached is thrown to them. 
The ship then circles the survivors, stops, and makes the rescue. 
The ring buoy, or similar piece of flotsam, should be painted yellow 
or orange to make them more visible. With this method, the line 
floats and does not require the accuracy that a standard heaving 
line with a monkey fist attached does, as survivors can swim 
to the line. 

Many times a survivor is so weakened by the cold water, or by 
the length of time he has been battling the sea, that he is unable 
to grasp a line passed to him. When this situation is met, a trained 
swimmer must be put over the side with a line to secure to the sur- 
vivor. After the line is made fast to the survivor, the swimmer 
accompanies him back to the ship. No man should be ordered over 
the side and into the water to assist in rescue operations unless he 
is wearing an exposure suit and has a line attached to him from the 
ship. Further, he should be a skilled swimmer, well versed in rescue 
techniques. Otherwise, he may himself become a man who needs to 
be rescued. 

In numerous survival incidents the moment of rescue has been 
attended by various dangers. These are usually brought about by 
underestimating sea conditions or lubberly handling. Rescuers 
with the best of intentions failed to realize the weakness and help- 
lessness of survivors. Thus, just as many were thanking God for 
rescue, they suddenly faced their worst moments. Exposure and 
dehydration are the two greatest hazards of survival at sea. These 
two are closely followed, however, by the hazards accompanying 
rescue. 

Survivors making shore landings have found it difficult to 
estimate the height and force of surf. Those being picked up at sea 
have faced equal hazards. On occasion, they have had to jump 
overboard to avoid being hit by the rescuing ship. Others have 
been battered and bruised trying to fend themselves off the side 
of the ship. It is not easy to climb up a rope ladder on a small ship. 
On a large one that is rolling in rough weather, it becomes very 
difficult. 


Following AMVER, probably the next major item assisting in 
SAR is the versatile helicopter. This aircraft can perform rescues 
while hovering above the water. Or, if of the amphibious type, it 
can land in a rough sea only a few feet from those in peril. 

On 3 January 1944, Commander Frank A. Erickson, U.S. Coast 
Guard, climbed into the cockpit of a small Sikorsky R-5 helicopter. 
His new and untried assignment revolutionized rescue techniques 
and earned him the distinction of flying the first helicopter mercy 
mission. Hampered by a severe storm, Commander Erickson flew 
his blood plasma-loaded craft from New York to Sandy Hook, where 
the U.S.S. TURNER had exploded. His efforts and success helped 
save the lives of more than 100 sailors and marked the beginning of 


22 


helicopter mercy and rescue operations. 
helped save thousands of lives. 

In answer to how far a helicopter can now fly without stopping, 
on 6 March 1965, the U.S. Navy flew a twin-engine Sikorsky SH-3A 
non-stop from San Diego, California to Jacksonville, Florida. To 
commence this record-breaking flight of 1,348 miles, the helicopter 
took off from the carrier HORNET and landed 15 hours and 52 
minutes later on the carrier FRANKLIN D. ROOSEVELT. The 
U.S. Navy has assigned this type helicopter primarily to anti-sub- 
marine warfare as combined hunter-killers. Although it averaged 
133.3 mph on the above-mentioned flight, in February 1962, it set a 
world speed record of 210.6 mph. 


Helicopters have since 


MAN OVERBOARD 


As previously mentioned, there is no one standard rescue pro- 
cedure, due to the many variables. If the man overboard is in sight, 
however, a good recovery approach, and perhaps the fastest, can 
be made using continuous full rudder in one direction. (Figure 3). 
The stern should be swung away from the man in the water. 

The bridge is not normally aware there is a man overboard, 
however, until the ship has passed him by. The initial turn is still 
made toward the side to which the man fell in hopes of moving the 
stern away. If visual contact can be maintained, a turn similar to 
that shown in Figure 3 promises to bring him back on board in the 
shortest time. 


Commence 
backing here 


K Reon, 


Path of Ship 
if rudder were left on 


Man overboard to port 
Rudder left full 


Figure 3 


Start of turn Completion of turn 


ONE TURNING Diameter _ | 
ORIGINAL | 


x -_- 
COURSE ® ‘ 


Man Overboard } 


When 60° from initial course 


60° 
7 
7 
£ 
\ 
\ 
Turn actually reverses here 
\ 
\ 
\ 
\ 
\ 
shift the rudder from right full \ 
to left full. PSG 5 alee 


Figure 4 
If visibility is restricted, a turn developed in 1942 by Commander 
John A. Williamson, USNR should be considered when the “man 
overboard” alarm is sounded. The Williamson Turn (Figure 4) not 
only turns the stern of the ship away from the man overboard, but 
also returns the ship to the approximate area where the man fell. 


SURVIVAL AT SEA 


To execute this maneuver continue the initial Full Rudder until 
60° from the original heading, then ordering the helm shifted. The 
60° is about right for most ships. However, different ship types 
may require from 30° to 80° change. The exact amount can be 
learned only by trial and error during “dry runs”. The ships heading 
will normally just reach 90° from the original heading as it com- 
mences to swing in the opposite direction. The turning should be 
continued until the reciprocal of the original course is reached. 
When the turn is completed, a ship should be heading back down her 
original track approximately one turning diameter from the point 
where the turn commenced. Thus, a careful search can be made 
back along the former track—the advantage of the Williamson Turn. 


U. S. Coast Guard official photographs 


23 


SCIENCE AND THE SEA 


SHARKS 


The history of attacks by sharks dates back to the beginning of 
written records. Displayed on the side of a vase, that is believed to 
have been painted approximately 725 B. C., are drawings of a sailor 
being devoured by a shark-like fish. 

Shortly after the New World was discovered, the Spaniards 
began to call the shark tiburon. While sailing with Vasco de Gama 
around Africa, Antonio Pigafetta wrote that “the tiburon have teeth 
of a terrible kind and eat people when they find them in the sea”. 

Pliny the Elder knew of the shark and referred to him as the 
dog fish. The word shurk made its debut to our vocabulary in the 
middle of the sixteenth century when an English sea captain placed 
one on exhibit in London. Although not known for sure, it is gen- 
erally believed that English sailors picked up the German word 
schurke, meaning villain. At any rate, the word seems to apply 
quite well. for the shark is truely a villain. 

Considerable controversy still apparently exists among mariners 
as well as some ichthyologists regarding shark attacks. Prior to 
World War II there was very little accurate information available 
on the subject of sharks. Some of our survival manuals flatly stated 
that sharks were cowards and would not attack an uninjured man. 
Authenticated reports and observations made during the war, how- 
ever, proved beyond doubt that some sharks will attack. 

Further, the insurance offered by shark repellent isn’t too 
promising. Some articles refer to it as absolute protection while 
others imply it is rather useless. The truth, however, is somewhere 
between these two extremes. The present day shark repellent 
consists of a packet of copper acetate and nigrosine dye. But, it 
has been demonstrated to have no inhibiting effect on the behavior 
of the species of sharks that inhabit the Caribbean Sea and Pacific 
Ocean. Therefore, the safest solution against shark attack is to 
get in one of the available life craft as soon as possible. 

A survivor of a Pacific Ocean aircraft ditching, in which sharks 
killed two men, said that using the repellent was “like feeding them 
orange juice.” Shark repellent loses effectiveness with age and 
should be in powder form. When it has hydrolyzed into cake form, 
it will not release the chemicals intended to provide the protection. 
Although not 100 per cent effective, repellent is the only weapon 
we currently have against hungry sharks. Hence, one should keep 
his repellent fresh and his powder dry. 

Other than repellent, there are other measures one may take to 
enhance his safety. 


While in the water: 


. Keep a sharp lookout for sharks. 

. Stay quiet and conserve as much energy as possible. 

. If swimming is required, do so with strong regular strokes 
Frantic irregular movements should be avoided. 

4. When threatened by a shark, try feinting toward it. 

some luck, it may scare him off. 

5. Loud noises have also been successful. With the hand cupped, 

regularly slap the water surface. Another method reported 

to frighten away sharks is to put one’s head under water and 

shout. One of the earliest accounts of this procedure working 

was of three survivors from a German submarine sunk off 

the west coast of Africa in 1943. They were attacked and 

bitten by sharks, but by submerging their heads below the 

surface of the water and “roaring”, they succeeded in 

frightening the sharks away. 


one 


With 


6. Do not swim directly away from a shark, but rather face him 
and try to outmaneuver him. 

7. If a group of survivors are threatened, form a circle, facing 
outward, and around any previously injured men. 

8. As a last resort, use your knife in self defense. 


While aboard a life craft: 


1. When sharks are known to be nearby, do not fish. 

2. Do not clean any previously caught fish nor throw any waste 
overboard while sharks are in the vicinity. 

3. If a firearm has been salvaged, shoot to kill. Shots close 
enough to the water to produce heavy concussion may ward 
off further attacks. 

4. Before going into the water, check for sharks under the 
life craft. 

5. If a shark threatens your raft, try jabbing his gills, snout, or 
eyes, with anything available. 

6. Any burials at sea should be conducted at night. 


The likelihood of shark attack is a very real concern to any 
mariner who finds himself in the water following a marine disaster. 
For there is no longer any question that sharks will attack and that 
a grave danger exists to anyone exposed to them. 

By and large, when sharks are successful in their attack they 
leave no evidence. Consequently, the number of missing swimmers 
who may have succumbed to them cannot even be estimated. 

To make a bad situation worse, sharks are found in all oceans 
and seas of the world. They may even ascend river mouths. All 
have voracious appetites. They are guided to their food by scent, 
sound, and sight. Further, they frequently travel in packs and feed 
at all hours of the day and night. 

A shark's sense of smell is developed quite highly and it is gen- 
erally believed that the presence of blood in the water tends to excite 
them. They are also very sensitive to sound vibrations transmitted 
through the water. Underwater explosions are known to draw them 
in search for food. Abnormal impulses, as those of a hooked fish, 
a dying animal, or a poorly-coordinated swimmer will draw sharks 
from a much greater distance than the scent of blood. This is the 
reason a swimmer should swim with powerful and even strokes. 

It has been the general belief of many mariners that a shark 
must turn on its side or back to bite. This is not quite true, for 
though a shark may turn partially on his side, he doesn’t have to. 
When a shark lunges forward in attack, he invariably arrives mouth 
first, with the entire front end displayed as mouth. It is possible 
for him to bite a man from most any position. 

Sharks may hunt for food and attack singly. The majority of 
survival accounts mention the presence of more than one. This is 
because once a shark finds a victim he is almost immediately joined 
by others in the same proximity. 

A most inconceivable aspect of a shark bite is the high percent- 
age of survivors that have been bitten who reported feeling no pain 
from the bite at the time. 

Two conclusions may be drawn concerning tiburon: One can 
never be certain what he will do, and the more we learn about him, 
the less we find we really know. 


24 


INTRODUCTION 


A primary function of the U.S. Naval Oceanographic Office is 
the improvement of its products used for navigating safely the vessels 
of the United States Navy, the mercantile marine, and others engaged 
in water-borne endeavors. The fulfillment of this function is a con- 
tinuing and ever expanding task as new knowledge of the worlds of 
inner and outer space is acquired. 

The era of modern navigation is generally considered to have 
been ushered in by Captain James Cook of the British Royal Navy 
during his three historic voyages of discovery into the Pacific Ocean 
between 1768 and 1779. This new era fostered the first steps in the 
transition of navigation from an art toa science. Today, with nuclear- 
powered vessels laden with highly sophisticated electronic navigation 
equipment and with experimental positioning satellites orbiting 
brightly in outer space, one might be tempted to say the transition is 
all but complete. Yet, we are all aware that the toll taken by 
groundings, collisions, and other marine casualties continues to rise 
in spite of all our electronic gadgetry. It thus appears that some of 
the old art, the seamen’s sense, is still very much needed by twentieth 
century mariners. 

There are many excellent works on navigation principles and 
techniques, such as the American Practical Navigator (Bowditch), 
where the navigator can find complete descriptions and solutions to 
about every known system of navigation. All too often, however, 
many of the little hints making up part of the art are buried so deeply 
within the text that they are overlooked. This article explores a few 
of these hints in an effort to stir new interest in them or even, perhaps, 
bring them to light for the first time. 


DEPTHS-SHOALS-CURRENTS 


The most important features of any chart are the soundings and 
depth curves by which the main characteristics of the bottom con- 
figuration are represented. The origin of the hand lead, the oldest 
known means of measuring depths, is lost in antiquity, but mention 
of soundings have been found in Egyptian records dating back several 
millenniums before Christ. An interesting account of the use of 
soundings and the danger they foretold is found in the twenty-seventh 
chapter of Acts of the Apostles. 

The present day mariner faces many of the same problems of 
his ancient predecessors when navigating off a strange and relatively 
unsurveyed coast. As the lead or echo sounder can only give the 
depth under or near the keel, there is no way to forecast the depth 
ahead for any substantial distance. 


25 


AVIGATIONAL 
HINTS 


By J. N. Spinning 
Maritime Safety Division 
U.S. Naval Oceanographic Office 


With this point in mind, the navigator should carefully examine 
each chart he uses. If there are no fathom lines shown on the chart, 
it is probably due to insufficient data or a highly irregular bottom 
relief. A coast so shown should be given a wide berth. The same 
caution is to be exercised in areas where only isolated soundings, 
especially when those marked “doubtful sounding” or those enclosed 
in a dotted ring are shown. Invariably, the rule to be followed is:— 
consider a coast to be foul unless it is shown to be clear. The only posi- 
tive way of determining that every pinnacle and obstruction has been 
found in an area is for survey vessels to wire-drag the area to a 
predetermined depth. Unfortunately, very few areas of the world 
have been surveyed so carefully. 

What constitutes a safe sounding will vary with different vessels, 
so that no hard and fast rule can be laid down. Generally, however, 
when only scattered sounding data are shown on the chart, partic- 
ularly along rocky coastlines, 10 fathoms should be regarded as a 
caution against the possible near approach to shallower water. When 
operating off a coast known to be well surveyed or when navigating 
inshore waters, as a useful aid, sketch in red ink or pencil a depth 
curve on the chart somewhat greater than the maximum possible draft 
of the vessel. This will provide the navigator with a meaningful 
danger line. The 10-fathom curve, if charted, can be traced with 
blue ink or pencil, or sketched in, and serve as a warning line. 

Charts made from surveys conducted by the Oceanographic 
Office are reduced to a plane of reference, with due regard to tides, 
which present the hydrography in its least favorable aspect. The 
datum planes most often used are mean low water, mean low water 
springs, and mean lower low water. The datum of charts based upon 
those of other nations is that of the original authority. 

Even with the charted soundings reduced to the lowest practi- 
cable plane of reference for the area, it should be remembered that 
local conditions will at times cause the actual water level to be lower 
than the chart datum. 

A change in wave formation is often an indication of shoaling as 
waves close up and heighten when running from deep to shoal water. 
A deeply laden vessel, especially during heavy weather, should, when 
possible, avoid transiting areas of abrupt changes in depths, as the 
seas running from the deeper water will follow the bottom rise and 
become sharper. 

In tidal estuaries, without marked irregularities of bottom, the 
maximum current velocity will occur at about half tide. The surface 
current is usually greater than that near the bottom, a condition 
which may enter into the navigation calculations of light and deep 
draft vessels. 


SCIENCE AND THE SEA 


ECHO-SOUNDING 


Submarine topography is becoming increasingly important to 
the mariner as a means of navigation. With the development of the 
modern sonic sounding equipment found on most naval vessels and 
many merchant ships, it is possible to record depths up to 6,000 
fathoms with an error of approximately one fathom. These sounding 
devices have made the profile of the ocean floor potentially the most 
universally accessible aid to navigation yet envisioned. Recent 
hydrographic surveys have given special prominence to this work 
and, as adequate bathymetric charts become available. navigation 
by underwater features may become as common as coastal piloting. 
Few bathymetric charts have been developed, however, for full réliance 
in navigation. 

The standard velocity of sound waves as calibrated for all 
American-made equipment is 4,800 feet per second. Although the 
true velocity varies wit1 local values of temperature, water pressure, 
and salinity, the difference is not considered important except in 
highly technical research work. It is the policy of the Oceanographic 
Office to chart all soundings on the basis of this standard value. 
Soundings obtained by equipment not calibrated to the American 
standard will not agree with the depths shown on H. O. Charts. 

Echo sounding equipment, like any aid, is subject to errors if the 
navigator is not fully familiar with equipment operating character- 
istics and limitations. The routine checks outlined in the instruction 
manual should be carefully conducted at least once a watch. 

The phenomenon known as “phantom bottom” has caused 
considerable confusion among many navigators. The phantom bot- 
tom appears on the trace as a bank between 125 and 375 fathoms 
below the surface and is only detected during daylight hours. The 
exact reasons for the occurrence of this phantom bottom return are 
not definitely known, but it has been experienced in most parts of 
the world. One theory offered is that concentrations of marine life 
descend to this area during daylight hours and then rise nearer the 
surface during the night. The navigator can often rule out these 
false returns by carefully checking them against known charted 
depths. 

Excessive underwater turbulence which aerates the water can 
distort the outgoing signal (sound waves) to the point of preventing 
any echo from being received. Usually, this condition is only a prob- 
lem when the vessel is rolling or pitching in heavy seas, backing down, 
or steaming in column formation. 

Another cause of significant error is fluctuation of the current 
supply driving the depth-indicator motor. The accuracy of 
soundings is directly related to the revolutions per minute of this 
motor which normally operates on a 60-cycle supply. A change of 
one cycle, say 61 cycles, would cause an error of about 33 fathoms in a 
recorded depth of 2,000 fathoms. The navigator should be alert for 
this problem at all times. 


NIGHT VISION HORIZON 


During World War II, with our submarine forces operating along 
hostile shores for prolonged periods of time, an urgent need arose for 
fixing position without revealing presence to the enemy. The use of 
electronic aids was too risky in most cases and had to be forsaken in 
favor of celestial observations taken late at night. 

Confronted with this situation, the submariners soon developed 
a highly reliable skill of observing stars against a night-vision hori- 
zon. The technique requires some preparation which at first may 
seem somewhat foreign to the surface mariner, but its usefulness 
should not be overlooked. 

The observer’s eyes must be completely “dark adapted.’’ Proper 
dark adaptation can best be accomplished by wearing red goggles for 
at least 30 minutes prior to going on the bridge for observations. 
Once on the bridge, and in complete darkness, the observer must 
spend an additional 20 minutes further adapting his eyes to the sky 
and horizon. Great care should be taken not to look at any light or 
to use binoculars, because, by so doing, dark adaptation can be 
instantly lost and the entire time-consuming procedure would have 
to be repeated. 

When the observer can see the horizon, he should send for a 
reliable assistant. The assistant brings the sextant, hack chronom- 
eter, and a flashlight fitted with a red lens emitting only a very dim 
light. It is also advisable for the assistant to dark adapt his eyes. 

Once on the bridge, the assistant hands the observer the sextant 
set at the approximate altitude of the first star to be observed. He 
then stations himself behind the observer, back to back, illuminates 
his hack chronometer and waits for the ‘““Mark!” 


26 


Navigator and assistant, having completely “dark adapted” their 
eyes, prepare to take round of sights against a Night Vision Horizon. Dark 
adaption can be instantly lost by looking at any artificial light source. 


The observer holds the sextant wpside down, pointed at the star, 
and brings the horizon up to the star. Next, the sextant is reversed 
and the star is adjusted to the horizon in the normal manner. During 
the observation it is extremely important that the observer does not 
look directly at the horizon. Instead, he should look up about 20°, 
keeping both eyes open and dim the star with a filter until it can 
scarcely be seen. When the observer is ready to ‘‘Mark”, both eyes 
are closed for about 5 seconds. The eyes are then opened wide and 
the sight taken when in focus. 

After the first sight is taken, the observer must be careful not 
to look at any light source until he has taken all the other sights he 
needs. The sights may then be worked by any method suitable to 
the observer. 


SIGHT ERROR COMPENSATION 


When possible, the navigator should take star sights both north 
and south of the zenith as this will tend to eliminate all systematic 
errors from the results. For example, one navigator might consist- 
ently bring his stars down too low, while another might tend to keep 
his too high; the horizon might be abnormally elevated or depressed; 
the actual refraction might be somewhat different than tabulated; 
or the sextant error allowed for incorrectly. 

If the total effect of these errors makes the altitude too high, a 
northern star will give a latitude too far north and a southern star 
too far south. 


ZENITH 
STAR STAR 
SOUTH NORTH 
OF ZENITH OF ZENITH 


2c 


sHiP N/ 


sHip S! Ap 


Figure 1. Sum of navigator’s systematic errors result in observed altitudes 

that are too high. 

In figure 1, the sum of the systematic errors, in each case, gives 
altitudes that are too high which result in apparent positions for the 
ship at N’ in the case of the northern star and at S’ for the southern 
star. The actual position lies about halfway between N’ and 
S’, at Ap. 

In figure 2, the sum of the systematic errors gives altitudes that 
are too low. The actual position, however, still lies at Ap, about half- 
way between the apparent positions, N’ and S’. 


ZENITH 
STAR STAR 
SOUTH NORTH 
OF ZENITH OF ZENITH 
hs A 
an\ Law 


Figure 2. Sum of navigator’s systematic errors result in observed altitudes 
that are too low. 


NAVIGATIONAL HINTS 


LATITUDE BY 
MERIDIAN ALTITUDE BELOW THE POLE 


Polaris is probably the most useful of all the stars in the higher 
northern latitudes and provides the mariner with his latitude, under 
reasonably favorable conditions, at any hour of the night. There is 
also another excellent, but seldom used, method of obtaining a 
much-desired latitude. This method involves finding the altitude of 
a circumpolar star when it is on the observer’s meridian below the 
pole. While the method can be used in both the higher northern 
and southern latitudes, it is especially useful in the southern hemi- 
sphere where no guardian of the south celestial pole, such as Polaris, 
is available. 

A cireumpolar star is by definition a star which revolves around 
the elevated pole without setting. This situation occurs when the 
polar distance of the star is less than the observer’s latitude and 
both have the same name. 


EAST 


Figure 8. 


In figure 8, AWBE is the diurnal circle of a cireumpolar star 
in the southern hemisphere. Line AB is the observer’s meridian. 
At A the star is on the observer’s meridian, bears south and has 
reached its highest altitude. During the next six hours, the star 
will fall towards the west. Then, continuing to fall, the bearing will 
curve eastward for six hours until the star reaches point B. At B 
the star is again on the observer’s meridian, bears south, and has 
reached its lowest altitude. From point B the star will rise towards 
the eastward for six hours, then while still climbing, it will curve west- 
ward completing one day’s revolution when it again reaches point A. 

To find the latitude, subtract the star’s declination as tabulated 
in the Nautical Almanac for the appropriate date from 90°. The 
result is the star’s polar distance. Add, to the polar distance, the 
corrected observed altitude when the star was at point B; the sum 
equals the latitude. The following example demonstrates the ease 
of the process. ; 

On July 4, 1965, after several days of squally overcast weather, 
conditions improved and the navigator observed Achernar close to 
being on his meridian below the pole. A series of observations were 
taken and finally a low reading of 20°12.1’ was obtained. . Knowing 
the height of eye was 44 feet and having no instrument correction, 
the navigator laid out the work: 


MERIDIAN ALTITUDE OF ACHERNAR BELOW POLE 


OBSERVED ALTITUDE 20°12.1' DECLINATION JULY 4 (—) 57°24.5'S 

ALTITUDE CORRECTION (—) 02.6’ (+) _90°00.0' 

HEIGHT OF EYE (—) 06.5’ 

TRUE ALTITUDE aru POLAR DISTANCE 32°35.5'S 
TRUE ALTITUDE 20°03.0'S 
LATITUDE 52°38.5'S 


NOTE: Corrections obtained from Nautical Almanac 


FIX RELIABILITY 


The pinpoint fix, whether obtained by stars, cross bearings of 
terrestrial objects, radio bearings or other means, is always a source 
of confidence to the navigator in that he knows his exact position at a 
specific time. Unfortunately, this single point is often very elusive 
and a round of stars or bearings leaves the navigator with a triangle 
or square for a fix. Some interesting hints about the latter merit 
review. 


27 


First, let us look at the case of star sights. As previously 
mentioned, a systematic error is often introduced in the observation 
of stars. Based on the assumption that this error is equal for each 
star, a very reasonable assumption, it becomes apparent that we can 
improve the fix reliability by properly adjusting the various lines 
of position. 

Proper adjustment means that each line of position must be 
moved equally in distance and direction, either all towards or away, 
from the bearings of the observed bodies. When this is done, the 
navigator many times is able to completely close the triangle or 
square. The amount of adjustment necessary is found by trial and 
error. Occasionally, the actual position will be found to be outside 
the original fix shape altogether. 


Figure 4. 


In figure 4, the solid lines represent the position lines of 3 stars 
after being advanced to a common time. The bearings of the 
observed bodies are indicated by the small arrows. The dashed 
lines represent the new lines of position after the navigator has 
shifted them equally towards the bearings, figure 4, (A) and (C), or 
away (B), in order to make them cross at a common point. Looking 
at (A) and (B), it is at once apparent the actual position does lie 
within the original triangle. In (C), however, it is obvious that the 
lines will cross only at some point outside the original triangle. The 
value of placing the small arrows on the various position lines, to 
indicate bearing, cannot be over emphasized. 


The desirability of taking stars to the north and south of the 
zenith has already been discussed. If, in addition, it is possible to 
take sights to the east and west of the observer, the best possible 
indication of fix reliability is obtained. In figure 5, the position lines 
of 4 stars are shown, with their bearings lying in the direction of the 
arrows. Looking at (A) and (B), it is again apparent that the actual 
position lies within the square and that the fix is reliable in both 
latitude and longitude. In (C), however, the latitude is reliable but 
the longitude is doubtful. 


A 


B Cc 
Z 


Before looking at the problems of reliability of terrestrial fi-es, 
let it be stated with the utmost emphasis that whenever three or more 
charted objects are available, a fix should consist of a minimum of 
three cross bearings. Even if the compass error is known, there is no 
check that a two bearing fix has been properly plotted on the chart. 
The third bearing will make any error in plotting immediately appar- 
ent. Frequently, a round of bearings, properly observed and plotted 
on an accurate chart, still do not cross at a common point. There is 
only one answer under these circumstances and that is compass error. 
This unknown compass error will affect each bearing by the same 
amount. By trial and error, the navigator can shift all the bearings 
clockwise, then counterclockwise until the bearing lines do cross at a 
common point. Often the vessel’s actual position will be outside 
the original triangle. The navigator has not only accurately deter- 
mined his position, but has also obtained the compass error which 
equals the number of degrees necessary to adjust the bearings. This 


Figure 5. 


SCIENCE AND 


hint is based on two important factors: one, that the chart is accurate, 
and two, that the bearings were accurately taken within a few seconds 
of each other. 


ASSUMED POSITION 


SUNKEN 


LOW ISLAND 


Light on Cape A: 
OBSERVED BEARINGS { seo on Point B: 


Flagpole on Low Island: 


Figure 6. When possible, at least three cross bearings should always be taken 
in obtaining a fix. If the bearing lines do not cross compass error may exist. 


In figure 6, the solid lines represent the observed bearings of 
three fixed objects on an accurate large scale chart. The navigator had 
properly observed and laid off the bearings and realized that the 
triangle formed was the result of unknown compass error. After a 
few minutes of juggling the bearings, equally clockwise and counter- 
clockwise, the navigator found that by adding 4° to each bearing that 
the lines of position crossed outside the original triangle. (the dashed 
lines.) The four degree adjustment revealed a previously unknown 
error of 4°E. in the compass. 


SPECIAL CASE 


There is a special case to be guarded against in the selection of 
terrestrial objects to be used in the cross bearing fix. A geometrical 
peculiarity which should be recalled is that through any three points 
not in a straight line, a complete circle can always be drawn, and only 
one. Now, if by chance the vessel itself is on or near this circle, a 
seemingly perfect fix can always be obtained. This situation is 
possible as compass error will in no way prevent the lines of bearing 
from crossing at a common point. 


COMPASS ALIGNMENT 


The true fore and aft alignment of the lubber’s line on the 
standard compass and pelorus is relatively quick and easy to deter- 
mine. This is accomplished by comparing the relative bearing of 
a distant object with that obtained by careful measurement on the 
chart when the vessel is alongside the dock and its true heading is 
known. The correct alignment of the lubber’s line on the steering 
compass, as a rule, is more difficult to ascertain. Some mariners 
take for granted that the alignment is correct and fail to check it. 
This situation, however, should always be investigated when first 
reporting aboard for duty and after yard repair or lay up. 

Cases have been recorded where the lubber’s line of the steering 
compass was off the longitudinal axis by 5 or 6 degrees. While 
azimuths reveal errors of the compass card, they do not disclose the 
error of a misaligned compass bowl. When the steering compass is 
so located that it is difficult or impossible to line up with the jack- 
staff, the error in alignment, if any, may be very closely determined 
by the following method: 

Ascertain the deviation on the four cardinal points by careful 
comparison with the standard compass or pelorus. Assign a (+) 
when the deviation is easterly or a (—) when westerly. Add the 
four figures together algebraically retaining the sign of the larger sum. 
Next, divide the result of the addition by 4. The remainder thus 
obtained is known as coefficient A and, if the compass is well made, 
is due for the most part to a misaligned compass bowl. When coef- 
ficient A is (+), the lubber’s line should be moved to the right the 
number of degrees indicated or if (—) moved to the left. 


28 


THE SEA 


CALCULATION FOR DETERMINING COEFFICIENT A 


DEVIATION HEADING NORTH —14° DEVIATION HEADING SOUTH + 8° 


DEVIATION HEADING EAST —18° DEVIATION HEADING WEST +12° 
TOTALS —32° +20° 

—32° 

+20° 

A Sie 

COEFFICIENT A — 3° 


In the above example, the lubber’s line should be moved 8° to the 
left to place it on the longitudinal axis of the vessel. 


MECHANICAL DEFECTS 


The compass, like any precision instrument, is subject to various 
mechanical defects which can easily go undetected for some time. 
Most common among these are broken or blunted pivot points, 
punctures or roughness of the jewelled cap, card not moving freely 
in the bowl, and excessive weight on the card itself. 

The mariner, with the aid of a small magnet, can quickly check 
his compass for defects of this nature by the following simple 
procedure: 

Note the compass heading, then using the small magnet draw 
the north point of the compass card about 15° to the right. Next, 
remove the magnet and record the heading when the card comes to 
rest. Repeat the process this time drawing the card about 15° to 
the left. If the card comes to rest each time on the original heading, 
the compass is free of the mechanical defects mentioned. A final 
heading differing from the original indicates one or more defects are 
present and that repair is needed. 


RETAINED MAGNETISM 


A change in course after a vessel has been steaming or lying on 
the same heading for some time is always attended by compass error. 
This error is caused by the retained magnetism induced while the 
vessel was on that heading. The exact amount of error can only be 
determined by observation, but can be expected to throw the vessel 
in the direction of the last course. The general rules regarding the 
error to be expected are: 

1. After steering for some time on westerly courses, expect: 

(a) Westerly error if you turn north; 
(b) Easterly error if you turn south. 
2. After steering for some time on easterly courses, expect: 
(a) Easterly error if you turn north; 
(b) Westerly error if you turn south. 


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Retained magnetism induced in a vessel after lying or steaming on 


the same course for some time always causes the compass to hold back in the 
direction of the last course. 


LOCAL MAGNETIC DISTURBANCE 


There are a few locations in the world where the charts show 
areas, usually very small in extent and located in relatively shallow 
water, where local magnetic disturbance of the compass is caused by 
magnetic mineral deposits on the bottom. Although numerous 
reports have been received concerning local magnetic disturbances, 


NAVIGATIONAL HINTS 


it is often impractical to definitely establish whether the cause was 
external to the vessel. Therefore, only the most probable of these 
reports are shown on the charts subject to later verification or 
disproval. 

Since magnetic force diminishes rapidly with distance, a mag- 
netic center in the visible land would have to be of unprecedented 
intensity to affect the compass of a vessel 14 mile from it. Mariners 
may note a temporary deflection of the compass when very close to 
another vessel, a large mass of iron or steel or when passing over a 
wreck in shallow water. The influence radius in such cases, however, 
will be very small. If the compass continues to show erratic behav- 
ior the cause is probably within the vessel itself. In most cases, the 
trouble is attributable to some source of artificial disturbing influence, 
such as swinging booms, change in location of iron or steel gear near 
the compass, or defective electrical wiring in the bridge area. The 
ordinary phenomena of static electricity will not cause any noticeable 
deflection of the compass. Severe magnetic storms, often associ- 
ated with sun spots or auroral displays, cause no more than a degree 
or so of deflection. Flashes of lightning, however, have been 
known to derange many compasses to the point of requiring complete 
readjustment. 

Regardless of how well the gyro is operating or how well adjusted 
the compass may be, routine observations, to detect abnormal devi- 
ation, should be made once every watch and after a course change 
of 15° or more. 


RADIO DIRECTION FINDERS 


Due to the reliance placed on radio bearings in fixing a vessel’s 
position, especially during periods of low visibility when celestial 
observations are unobtainable, the shipboard radio direction finder 
deserves the same care and consideration the navigator gives his 
sextant and the compass. Like these instruments, the direction 
finder has certain errors which can be minimized greatly by the skill 
and sound judgment of the operator. In order to obtain the maximum 
built-in potential of the equipment, it is essential that the navigator 
take every opportunity available to use the direction finder in good 
weather when results can be checked by other means. By so doing, 
the reliability of fixes obtained during adverse conditions can be more 
accurately ascertained. 

Discussions on radio direction finders often refer to the effect of 
coastal refraction (land effect) stating that errors may be expected 
when radio bearings are taken by ships so located that the line of 
sight to the radiobeacon passes over land or along the shore. Exten- 
sive observations, however, seem to indicate that when the vessel is 
well off the shore this error is negligible. Bearings secured entirely 
over water areas are, of course, more desirable as any question of the 
coastal refraction error is thus eliminated. 

Radio bearings taken on commercial entertainment broadcasting 
stations, on the other hand, should be viewed with extreme caution. 
The mariner must consider that the operating frequencies of such 
stations (550 to 1600 kes), as compared with marine or aeronautical 
radiobeacons which operate well below 550 kes, will require materially 
different calibration curves or compensation adjustment. Several 
other factors affecting reliability of bearings taken on such stations 
are:—the published position of the station may be that of the studio 
and not the transmitter site; the position coordinates have not been 
adjusted to the datum of the nautical chart being used; the trans- 
mitter may be located well inland, causing excessive coastal refraction 
error; and that the station may be synchronized with other stations, 
making identification of the transmitter impossible. 

The navigator, considering all the foregoing limitations, may 
still be able to use certain commercial stations to good advantage. 
This can only be determined by carefully checking positions obtained 
from an individual station when the vessel’s position is accurately 
known by other means. 

The radio direction finder, like the compass, should be checked 
for deviation after changes in its surroundings have taken place and 
on a routine basis. It should be remembered that the compensated 
sets are just as vulnerable to changes in the position of ship’s gear as 
are the non-compensated sets. 

Each year the Oceanographic Office receives many inquiries 
asking why a certain aeronautical radiobeacon or light is not charted 
when it can be heard or seen for many miles at sea. 

The Office welcomes ail such inquiries and thoroughly investi- 
gates each one. The mariner should bear in mind, however, that 
these aids are placed for the maximum use of aircraft and not for 


356-697 O- 69-4 


29 


surface vessels, a factor which must be carefully considered before 
placing these aids on a nautical chart. Many aeronautical radio 
aids and lights are moved from one area to another as seasonal wind 
and weather patterns change. The fact that such a relocation has 
taken place is not always made known immediately to maritime 
interests. The aeronautical radio aids listed in H. O. Publications 
117A and 117B meet or surpass what the Oceanographic Office 
considers the minimum requirements for safe surface use. The 
aeronautical lights listed in the various volumes of Light Lists also 
meet this criterion. 


SOUND SIGNAL CAUTION 


The whistle, horn and bell serve as the principle means of com- 
munications for vessels to indicate or learn presence and intent or fact. 
The transitory nature sound transmitted by these devices has a 
significant bearing on their reliability as a navigational aid and a 
communications link. As now used, the various coded signals 
indicate not only presence but type of vessel (such as tug with tow, 
sail, or power-driven) and nature of the vessel’s activity (such as 
underway, at anchor, backing down, or approaching a bend). There 
is a great deal of evidence to indicate that the failure to correctly 
hear or respond to sound signals is a major contributing factor in 
ship collisions. 

A study of the testimony given following numerous collisions, 
resulting in damage in excess of one million dollars, occurring in good 
visibility under inland rules, reveals that the significant factor 
bringing about many of these collisions was the watch officer’s belief 
that he had heard a signal other than that actually sounded. Inland 
rules require not only establishment of intent, but also agreement by the 
vessel signalled. With such a built-in safety factor in the rules, 
collision must then be the result of either human failure or 
overconfidence. 

Let us look at the cause of one collision; where the main ingre- 
dient responsible has been experienced by almost every watch officer. 
A vessel approaching another desired to take the starboard side of 
the channel for a port-to-port passing situation and so indicated this 
by sounding one short blast. The blast, however, amounted to little 
more than a wisp of steam and a rather sick gasping cough barely 
audible on the vessel’s own forecastle head. The watch officer, real- 
izing that the approaching vessel could not possibly have heard the 
signal, sounded another short blast. This second blast was very 
clear and audible. Unfortunately, the watch officer on the signalled 
vessel observed the wisp of steam from the first attempt, but due to 
noise on deck had concluded that he had just not heard it. Then, 
both seeing and hearing the second short blast, he assumed that the 
other vessel had sounded two short blasts, answered in kind, and 
altered his course into a costly collision. 

Overconfidence in the old saying “‘seeing is believing” certainly 
spoiled his day! The officer initiating the signals also lacked good 
judgment in sounding the second blast so soon after his first unsuc- 
cessful attempt. There appears to be a definite reluctance on the 
part of many watch officers to sound the danger signal, as required 
by the inland rules, when the intentions of the other vessel are in 
doubt. This reluctance probably stems from the desire not to unduly 
alarm the master, but the sounding of four or more short rapid blasts 
to indicate uncertainty is much less alarming than maneuvering a 
vessel on assumption and guesswork. 


RADAR LANDFALL 


One of the more hazardous situations confronting the mariner 
involves the approach to land during poor visibility, especially after 
several days of overcast weather conditions when sights of doubtful 
value have been obtained and uncertain currents encountered. 

The situation is further aggravated when the approach course 
makes a small angle with the coastline; where, due to depth of water, 
soundings are of little avail, and there are offshore shoals and reefs to 
be avoided. The mariner’s main objective in this situation will be to 
identify, without any doubt, some feature and determine the vessel’s 
position relative to it. 

Charts are constructed with the emphasis placed on depicting 
the most prominent visual features for idéntification, such as con- 
spicuous spires, domes, tanks, towers and so on. While these objects 
may be excellent visual landmarks, they may be extremely poor radar 
contacts, particularly if previous radar experience in the area is 
lacking. 


SCIENCE AND THE SEA 


Preparation is therefore very desirable when approaching land 
in poor visibility with the aid of radar, so that the mariner may make 
a sound prediction of what should be seen and when. To do this, he 
must acquire a thorough understanding of the capabilities and limi- 
tations of his radar equipment, knowledge of the meteorological 
factors, either favorable or unfavorable, which will cause anomalous 
wave propagation, and some means of determining the distance off 
at which features of various heights will begin to appear above the 
radar horizon. 

Radars operate in the frequencies that are essentially line-of- 
sight, but due to barometric pressure, relative humidity, and 
temperature gradient variations the waves are subject to some 
bending, either up or down, under certain atmospheric conditions. 

The normal radar horizon is approximately 15 percent greater 
than the visual horizon at the same height. The approximate 
distance at which a feature will be on the horizon of the radar set is 
found by adding the distance of the radar horizon of the antenna to 
that of the feature, or can be computed by the formula:— 


D=1.23 \/Ha+1.23 \/Ht 


D=distance in nautical miles 
Ha=height of antenna, in feet 
Ht=height of target (feature), in feet 


Radar horizon is 15% greater than visual horizon. 


The following table gives the approximate distance to the radar 
horizon for a standard 3-cm radar under normal conditions for 
various heights of either Ha or Ht. 


APPROXIMATE DISTANCE TO RADAR HORIZON 


HEIGHT (ft.) DISTANCE OF HEIGHT (ft.) DISTANCE OF 
Ha or Ht RADAR HORIZON (N. M.) Ha or Ht RADAR HORIZON (N. M.) 
18 5 215 18 
24 6 240 19 
32 7 265 20 
42 8 320 22 
54 9 380 24 
66 10 445 26 
80 VW 520 28 
95 12 595 30 
WwW 13 680 32 
130 14 779 34 
150 15 860 36 
170 16 960 38 
190 7 1060 40 


(3-cm radar and normal conditions) 


Inspection of the above table would indicate to the mariner whose 
radar antenna was €0 feet above the water, that a coastal bluff 80 
feet high would not be visible on his radar scope until the vessel was 
within a maximum range 20.5 miles and the chances are that the bluff 
would have to rise above this maximum radar horizon distance before 
the reflected echo was strong enough to show upon the radar scope. 
The knowledge of the probable distances at which various objects 
can be expected to appear on radar will greatly assist in the accurate 
identification of various landfall targets. A more graphic means 
of showing target range can be had by constructing a simple curve on 
a piece of graph paper using the height of the mariner’s own antenna 
based on the above table. 

As with all other aids to navigation, the use of radar in good 
weather to check out target identification, ranges and skill of the 
operator will return valuable dividends when visual identification 
is not possible. 

Regardless of how simple and direct the radar presentation may 
appear, it is essential that the navigator continue to employ all normal 
navigational techniques when in coastal waters. The navigator can- 
not afford the luxury of not maintaining a good dead reckoning 
position plot, a sharp eye on the soundings and awareness of the 
effects of set and drift conditions upon the vessel. 


ICEBERG DETECTION 
While any suggested signs, warnings or proposed methods of 


detecting the proximity of icebergs may prove of great assistance, 
they can be but supplementary to the eyes of an alert lookout. The 
old phrase that the only sure sign of an iceberg is to see it is still a very 
valid one. Over reliance in any other means could be extremely 
dangerous. 


——— Jae 


.. -YERY CLEAR DAY 
18 MILES 


Distance al which a lookout can sight icebergs under various 
atmospheric conditions. 


The distance at which a lookout can sight a berg varies, of 
course, with the state of visibility, height of eye and height of berg. 
On a very clear day a lookout stationed 70 feet above the water could 
sight a large berg up to 18 miles; in clear weather, with low-lying haze 
on the horizon, the top of a berg at 9 to 11 miles; in light fog 
or drizzling rain at 1 to 3 miles; and in dense fog about 100 yards. In 
light fog the lookout could sight a berg sooner if aloft, but in dense fog 
a position in the bow would be best. On a clear starlit night, a look- 
out will not sight a berg more than one-fourth of a mile away. If the 
bearing is known, however, this distance could be increased to one 
mile, with the aid of binoculars, by picking up the occasional spots 
of light as the swells break against it. On a bright moonlit night, a 
berg could probably be sighted up to 3 miles away. 

As a general rule, there is no appreciable change in the air tem- 
perature near a berg nor in the water temperature surrounding it. 

The presence of growlers and other pieces of detached ice usually 
indicates that a berg is in the vicinity and probably to windward. As 
growlers can cause considerable damage to a vessel, it is always best 
to pass a known berg on its windward side, especially at night or in 
low visibility. 

The use of radar to detect the presence of bergs and growlers is 
certainly helpful, but often a large berg that has been sighted visually 
will not appear on the radar scope. This is probably due to the berg 
having a very smooth sloping side or because of sub-refraction which 
often occurs in ice areas. Many times, a berg detected by radar will 
disappear again from the scope as the relative positions of the berg and 
the ship change. 

The detection of growlers by radar is even less certain. The 
echoes returned by these small bergs, which show only a few feet above 
the surface, are difficult to distinguish from strong sea clutter on the 
scope. 

The following table shows the approximate maximum range 
that bergs can be detected by a 3-cm radar with the antenna located 
50 feet above the water: 


HEIGHT ABOVE WATER RANGE (N.M.) 
Large icebergs 40—50 feet 12 
Medium-sized icebergs 10—20 feet 9 
Growlers 6—10 feet 2 


PIN POINT ANCHORING 


The following method of instantaneous plotting of a ship’s 
position approaching and anchoring in an assigned berth has been 


NAVIGATIONAL HINTS 


found to be valuable in crowded anchorages. 

A chart, preferably an anchorage chart of the area is prepared in 
the following manner: 

Three or four prominent points or objects, preferably good radar 
targets, which give a coverage of the entire anchorage area as well as 
furnishing the widest possible angles of bearing are selected. From 
these selected points lines of position are drawn at 1-degree intervals 
covering the entire anchorage area, using a different colored ink for 
the lines drawn from each point or object. The bearing lines are 
extended beyond the anchorage area and the true bearing from the 
objects or targets marked on the extremities of the lines. Upon 
assignment of an anchorage berth, range lines in any desired incre- 
ments are laid down in ares with pencil from the selected points to 
the assigned berth. The prepared chart is now ready for use, overlaid 
with inked lines of position from the selected objects for bearing pur- 
poses and penciled arcs in the vicinity of the assigned berth for 
ranging purposes. 

As the vessel approaches the assigned berth instantaneous fixes 
may be obtained, as rapidly and frequently as desired, merely by 
noting the bearings as the observer at the bearing circle gives them 
to the navigator at the prepared chart. The navigator simply marks 
the ship’s position where the bearing lines cross. The radar ranges 
are also given at the same time as a further check on the ship’s posi- 
tion. By setting a universal drafting machine or parallel rules on 
the ship’s course line and placing same on latest fix any course changes 
are immediately apparent. A further refinement could be made by 
placing red-penciled range rings in increments of 100 yards from the 
center of the assigned anchorage berth in order to rapidly read off 
the remaining distance to the berth. 

This method requires a navigation staff normally found on board 
a naval vessel. It may, however, be useful to the merchant navigator 
when assigned to a congested anchorage berth. It could also be used 
by a vessel regularly running a congested channel or restricted man- 
euvering area for obtaining positions, requiring only a minimum 
amount of time in the chartroom. 


31 


Simplified chart shows only bearing limits passing through desired 

In practice, bearing lines at 1-degree intervals would be drawn 
from selected landmarks in different colors and marked at their extremities. 
Range circles, at suitable scale, would be drawn from center of anchorage to 
indicate distance remaining. 


anchorage. 


CONCLUSION 


When one stops to consider that the art and science of navigation 
are a coalescence of astronomy, cartography, mathematics, geography, 
history and man’s unquenchable desire to explore the unknown, it is 
easy to see that the skillful mariner must have a tremendous reservoir 
of facts, hints and common sense to fulfill his mission. The Oceano- 
graphic Office endeavors to assist the mariner in every possible field 
of safe navigation and solicits the mariner’s comments and sugges- 
tions for the improvement of its products in a mutually beneficial 
program of maritime safety. 


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FISHERIES 


VESSELS 


AND GEAR 


By J. N. Spinning 
Maritime Safety Division, 
U.S. Naval Oceanographic Office 


The unprecedented expansion of fishing fleets throughout the 
world and the development of new fisheries and harvesting techniques 
are matters of ever-increasing importance to every watch officer. As 
encounters with the vessels, men, and gear competing for this rich 
protein supply become more frequent, the need for mutual safety will 
become more demanding. To adequately meet this demand watch 
officers need more than a seamanlike curiosity of those with whom they 
share the sea. This article explores the dominating factors which 
create, develop, and sustain a fishery, and fashion its tools of harvest 

Today, there are well over one million vessels actively engaged 
in the time-honored fishing profession. Vessels range in size from the 
large factory mother ship down to the most primitive native canoe 
Each vessel, however, regardless of size, shape or means of propulsion, 
shares one common goal: to catch fish as efficiently as the circum- 
stances permit. 

The type of fishery and means of harvest play a significant role 
in the design and equipment of every fishing vessel. Although only a 
few vessels are so specialized that they can engage in just one fishery, 
most vessels are limited to one harvesting technique, or perhaps two 
for different seasons. 

For generations prior to the Second World War, fishermen 
working from small vessels were content to fish the waters contiguous 
to their home ports. Relatively few ventured far from their native 
shores. World War II saw large numbers of fishing craft lost, 
destroyed, or rendered unseaworthy due to deterioration and neglect 
Faced with a hungry post-war population and a meager fleet, the 
fishing industry embarked on an urgent program of rehabilitation 
and expansion. 

Stimulated by government, and aided by far-reaching technolog- 
ical advances in science, food processing, and harvesting techniques, 
the industry has made tremendous strides toward meeting the world’s 
need for fish. This fact can readily be appreciated when we note that 
the total world catch has more than doubled during the past 15 years. 
Figures from the Yearbook of Fishery Statistics, now considered the 
most reliable source of what, where, and how much is caught, reveal 
that 217 countries, territories and island groups caught a total of 
51.6 million metric tons of fish and other marine animals during 1964. 
The Yearbook also shows that of these 217, only 42 had catches over 
100,000 tons and that they accounted for 95 percent of the catch. 
Only 12 countries had catches in excess of one million tons. 

The following table shows the relative standings of the 12 major 
fishing nations based on the metric tons landed during 1964. 


WORLD STANDING 1964 


Metric Tons Metric Tons 
(Million) (Million) 


Position Position Country 


Country 


1 Peru 9,130,700 7 India 1,320,300 
2 Japan 6,334,700 8 South & West Africa 1,254,500 
3. Mainland China 5,800,000 9 Canada 1,210,700 
4 Soviet Union 4,475,800 10 Spain 1,196.600 
5 United States 2,638,000 ll Chile 1,160,900 
6 Norway 1,608,100 Denmark & Faroe Islands 1,010,200 


*Estimated 


33 


CLASSES AND METHODS 


Fish are classified as either pelagic or demersal. Pelagic fish are 
those species that live at or near the surface; included in this group 
are salmon, tuna, menhaden, mackerel, and herring. Demersal fish 
are those varieties that live at or near the bottom; included in this 
group are haddock, cod, rosefish, pollock, flounder, and all types of 
shellfish. 

While there are virtually endless variations in the methods of 
harvesting fish, they can all be listed under one of three major groups: 
direct attack, snaring or luring. Direct attack embraces all techniques 
using such gear as harpoons, spears, dredges, rakes or tongs. Snaring 
covers all methods of making the catch by nets such as trawl nets, gill 
nets, purse seines, ring nets, or pound nets. Luring includes all forms 
of bait fishing where the fish or crustacean is enticed to bite a hook 
or crawl into a trap. 

One fishing community may prefer one particular technique for 
harvesting the crop while a different method is favored elsewhere. 
The vital factors of capital to finance the operation, local market 
conditions, abundance of fish, and type of grounds all play key roles 
in the ultimate choice. 


FOOD CYCLE 


Relatively few of the more than 40,000 species of fish exist in 
sufficient concentrations to make commerical harvesting economically 
feasible. A large concentration of fish requires a proportionately large 
food reservoir. It follows, therefore, that commercial fisheries can 
develop only in those areas where the physical properties of the sea can 
support ample organic growth. 

The food cycle is predatory in nature. It begins with tiny surface 
plants called phytoplankton using the sun’s energy, through photosyn- 
thesis, to build organic tissue from dissolved inorganic materials in the 
sea. This involved process can only take place in the light-penetrated 
surface layers called the ewphotic zone. These tiny phytoplankton 
serve to feed a multitude of small animals called zooplankton. Zoo- 
plankton provide the main source of nourishment for small pelagic fish 
which in turn fall prey to larger species of pelagic and demersal fish. 

This food cycle tends to be long and inefficient when there is little 
change in the water layers within the euphotic zone. As the rate of 
surface water replenishment increases, due to upwelling and mixing of 
moving water masses, the abundance of marine life increases. Up- 
welling is caused primarily by water from the lower depths rising to 
replace the surface water which has moved away from the shore. This 
surface movement is due to the action of the prevailing alongshore and 
offshore winds coupled with the normal deflection caused by the 
earth’s rotation. The resultant exchange of nutrients stimulates 
vigorous organic activity. It is in the areas of greatest upwelling and 
mixing that most of the commercial crop is _ harvested. 


TRAWLERS 


A frequent error made by watch officers, and lookouts alike, is 
the assumption that every fishing vessel sighted is a trawler. The basis 
for this assumption undoubtedly stems from the large number of 
actual encounters and the fact that they appear in all sizes and 
shapes. Trawlers may be broadly classed as either side or stern trawl- 


SCIENCE AND THE SEA 


ers. Each class has definite characteristics which make accurate 
identification a simple matter regardless of size. 

The key feature to side trawler identification is the pair of heavy 
A-frames they all carry. These A-frames, each fitted with a block, are 
mounted on one or both sides, with one located well forward and the 
other aft. A large winch is mounted on deck forward of the wheelhouse 
to handle the trawl warps. Once the trawl is streamed these warps 
are secured to a special towing block on the vessel’s quarter. Trawling 
speeds vary from 2 to 5 knots. 

A typical North Atlantic side trawler is shown in figure 1. This 
195-foot trawler, built by Brooke Marine Limited of Lowestoft, 
England, is arranged to trawl from the starboard side only, providing 
for spacious Officer’s quarters on the port side. The vessel has an 
iced fish hold capacity of 18,200 cu. ft., a loaded speed of 14 knots, 
and a complement of 26 men. 


we 
ELL 


eee 


Figure 2 


In recent years the trend in new trawler construction has been 
toward building stern trawlers rather than the conventional side types. 
Most stern trawlers over 150 feet in length are equipped with fish 
processing machinery, and excellent refrigeration or freezing facilities. 
Located near the stern, which often has a trawl slipway, is either a 
swinging gantry or a fixed gantry for handling the trawl warps. 

On those vessels having the trawl slipway, the catch is hauled 
directly aboard via the slipway to the working deck where the fish are 
eviscerated and washed before being sent to the processing rooms. 
Stern trawlers without the slipway bring the catch over the stern by 
means of the hydraulically-operated gantry. 

The 180-foot stern trawler Seahorse, built by Brooke Marine 
Ltd., is shown in figure 2. The design incorporates a soft nose stem, 
well flared bow, and a transom type stern with hydraulically powered 
gantry. This vessel has a 9,500 cu. ft. fish hold capacity, a loaded 
speed of 10.5 knots, and carries a crew of 18. 


Accompanying the trend toward stern trawler construction has 
been the increased interest in, and use of, mid-water trawling gear. 
Mid-water trawls permit vessels to fish either on the sea bed for 
demersal species or at any desired height above it for pelagic varieties. 
To accommodate this dual capability with one trawl requires some 
modification of the conventional otter board trawl. Many design 
concepts have been developed and tried with varying degrees of 
success. One promising design, however, is the versatile Grouselle 
trawl from France, shown in figure 3. 

The Grouselle trawl has a trapezoidal-shaped opening with two 
triangular fillets between the wings and start of the cod end, a head 
line, and ground line. The float equipped head line trails behind the 
ground line which takes most of the strain during trawling. The head 
line is trailed as fish tend to dive in their attempt to escape the 
approaching net, an important consideration in mid-water work. 


The Grouselle trawl 


~ 


Figure 3 


34 


FISHERIES VESSELS AND GEAR 


From the outboard ends of the head line, two upper lines are run to 
the towing warps well forward of the otter boards. A ‘“‘Pilot’’ panel 
is secured to each upper line close to the point where it leaves the 
head line. These ‘‘Pilot’’ panels provide the necessary outward 
divergence to keep the net’s mouth fully open in both a horizontal and 
and vertical plane. 

Stabilization of the otter boards, which would have a tendency 
to capsize during mid-water trawling, is accomplished by securing a 
“Pilot’’ panel to each board. These stabilizing panels are secured by 
eye-bolts and assume a position during trawling outside of, and 
slightly higher than, the otter boards. 

Prior to the development of special gear, such as the Grouselle 
trawl, mid-water trawls required towing warps six to seven times as long 
as the desired fishing depth. These extremely long warps made net 
handling slow and difficult. Now, with the aid of ‘‘Pilot” panels 
which cause rapid plunging as warp is paid-out or rising as taken in, 
towing warps no longer than needed for normal bottom work may be 
used for mid-water fishing as well. 

Trawling has for many years been a dominant harvesting 
technique employed by the North Sea, Barents Sea, Iceland and 
Grand Banks fisheries. In the Pacific Ocean, both the Japanese and 
Russians operate large well-equipped trawler fleets off the Aleutian 
Islands and around the Sea of Okhotsk. Trawler operations require 
a substantial capital outlay which has held back development of 
important new fisheries in many of the less advanced nations. This 
situation, however, can be expected to continually improve as the 
world protein shortage forces these nations to look to the sea for 
survival. 


PAREJA TRAWLING 


The pareja trawl, or pair trawl, constitutes another major har- 
vesting technique in which a net is towed over the bottom. Pareja 
trawling requires the services of two vessels steaming or sailing abeam 
of each other with the net towed between them. Spanish pareja 
vessels are a familiar sight in the waters between Morocco and the 
Irish coast including the Bay of Biscay. 

Since pareja trawls are towed between two vessels, they do not 
need the heavy otter boards and associated gear to keep the net’s 
mouth open. The resultant rig, being much lighter, also reduces net 
buffeting and damage to the catch. Pareja-caught fish, therefore, 
arrive at: market centers in better condition than those caught by 
otter trawls. Less towing power and larger nets are additional ad- 
vantages derived from the lighter rigs. 


Figure 4 


The 85-foot Spanish pareja 
vessel Ala-Izan (Fig. 4) was 
built by Hall, Russell and Co., 
Ltd. of Aberdeen, Scotland. 
This vessel is typical of the 
older vintage pareja craft still 
working. 


A pair of pareja vessels, after streaming the net, take up station 
abeam of each other at a range of one-half to three-quarters of a mile 
apart. Towing speed is about 2 knots. As resistance on the trawl 
increases during harvest, this range is slowly closed until both vessels 
are close aboard at the end of towing period. Crews then take turns 
hauling in the net and stowing fish. Because of the close range 
involved during trawl recovery operations, fishing is usually limited 


to daylight hours. At no time should any vessel attempt to pass be- 
tween a pair of pareja vessels engaged in fishing. 

Pair fishing is also widely practiced by Chinese fishermen in the 
China and Yellow Seas using the traditional sailing junk with no power 
save the wind. 

During the past few years, however, there has been an extensive 
modernization program underway in Hong Kong sponsored by the 
Fisheries Division of the Colony’s Department of Agriculture and 
Fisheries. Through a development loan fund, fishermen are 
encouraged to put auxiliary power into their sampans and junks to 
increase their catching capability. Experiments have shown that 
catches made by powered craft are considerably higher than those 
made by similar craft without power. Increased catches and better 
marketing controls enable fishermen to pay back their loans and 
enjoy a better standard of living. Officials estimate that 65 percent 
of the Colony’s more than 9,000 fishing vessels now have auxiliary 
power as a result of this program. 

The fishing junk, with or without auxiliary power, is characterized 
by its two masts, low poop, and heavy windlass as compared with 
three and four masted cargo /passenger varieties. 


Figure 5 Fishing junk 


LONG-LINE FISHING 


Small open boat long-lining, as once practiced extensively by the 
famed Grand Banks dorymen, has all but vanished from the list of 
principal harvesting techniques. Decline of this man-against-the-sea 
epic can be attributed to increased trawler activity, and a growing 
shortage of dedicated seamen willing to endure the hardships and 
loneliness of dory work. 

Today, most commercially important long-lining is conducted 
directly from medium-sized, well-equipped, power-driven vessels. 
Lining does not dictate vessel design, therefore, a wide array of vessels 
are found within the various fisheries with no distinctive characteristic 
readily evident. Rather, it is the gear itself which reveals the most 
intelligence to an observer. Lining falls into two categories; subsurface 
and bottom. 

Subsurface long-lining as pursued by Japanese offshore tuna 
liners is probably the most active and ambitious effort to be found 
in any fishery. 

In essence, a long-line is merely a series of individual baskets of 
line joined together to form a continuous fishing rig up to 15 miles 
or more in length. Each basket, the basic unit of gear, contains from 
600 to 2,000 feet of line. 

In subsurface lining a main line, usually of nylon or wire con- 
struction, is suspended horizontally at the desired depth by means of 
glass buoyed float lines. Tuna main lines, for example, are set so that 
hooks will be between 50 and 300 feet below the surface depending 
upon species to be caught. In addition to the glass floats, a flagged 
bamboo pole marker is secured to each float line. These flagged 
markers serve to indicate direction of lay and to warn approaching 
vessels of the rig’s presence. 

At intervals along the main line, are fastened branch lines called 
droppers. The length of these droppers and the number used per unit 
of gear varies with different fisheries. Each, however, consists of 
a nylon or cotton section, a swivel, and a wire leader secured to a 
baited hook. 


SCIENCE AND THE SEA 


After the liner has set all her gear, she returns to the starting 
point and commences to work her way back along the rig. The main 
line is hauled aboard by a power-driven line-hauler. Once aboard, 
catch is removed, hooks rebaited, and gear reset. 

Subsurface long-lining has proved highly successful for harvesting 
albacore, yellowfin, bluefin, and bigeye tuna. Identification of this 
gear is very simple due to the long string of glass floats on the surface, 
and the flagged markers. 

Bottom long-line operating procedures are quite similar to those 
of subsurface lining. Instead, however, of suspending the main line, 
it is anchored to the bottom. Flagged bamboo pole markers are again 
used to mark the course and also the anchor sites. Glass floats are not 
required. Line hauling and baiting routines are carried out in the same 
fashion described for subsurface rigs. Bottom lining is the principal 
harvesting method used by the large halibut fishery off the United 
States Pacific coast. Figure 6 depicts a typical subsurface and bottom 
long-line rig. 


a 
¢ TT ma = A. Subsurface long-line rig B. Bottom long-line rig 
\ Figure 6 


o—Herd and Mackenzie Limited 


Atlantic long-liner 


DRIFTERS 


Drifters, once the very heart of the British, Scandanavian and 
European pelagic fishing industry, have steadily declined in number 
over the past 20 years. Norwegian fishermen, for example, are sub- 
stituting purse seines for drift nets with excellent results. In fact, 
Norwegian purse seiners harvested 400,000 tons of fish during 1964 in 
the North Sea alone. This was about one-half the total catch. Many 
British drifters have been converted to near-water trawlers, and now 
engage in demersal or pelagic fishing, depending on season and 
abundance of fish. Regardless, however, of their diminishing strength, 
drifters still contribute substantially to the total annual catch. 

Drifters usually operate in fleets within 10 to 60 miles of their 
base port. Throughout the season, base ports must be shifted as fish 
migrations dictate but are always adjacent to the grounds being 
worked. Actual fishing operations are conducted only between dusk 
and dawn. During this period, a concentration of drifters present a 
formidable navigational hazard to any vessel wishing to transit the 
area. Radio navigational warnings are occasionally broadcast when 
concentrations of drifters are unusually large. If possible, the prudent 
watch officer should alter his course and go around the fleet. Timely 
action will not only prevent possible loss of an expensive net, but will 
save incalculable strain on the nervous systems of all concerned. 


The 75-foot vessel Fragrant Rose (Fig. 7) was built by Herd and 
Mackenzie Limited of Buckie, Scotland. This craft (s rigged as o 
drift net herring fisher 


North Sea vessels average between 60 and 100 feet in length and 
are either steam or diesel-powered. Designed to bring in fresh fish, 
they operate on short trips and have limited accommodations for crew 
or provisions. Once nets are out, a small triangular or gaff-rigged 
mizzen sail is set to increase stability and keep vessel’s head into the 
wind. A pivoted derrick boom and large capstan are located well 
forward for handling the catch. To reduce rolling, this pivoted boom 
is normally lowered and cradled on the wheelhouse roof when not in 
service. 


Photo=U S Fish and Wh 


Pacific halibut long-liner 


FISHERIES VESSELS AND GEAR 


The general migratory patterns of commercially sought pelagic 
species in the North Sea region are well documented by long 
experience. Individual vessels, however, still face the problem of 
precise location at a specific time. Although an important question 
in any fishery, it is more manifest in the case of drifters. For once the 
net is out, drift net fishing becomes the most passive form of all 
harvesting techniques. A catch depends solely on the fortuitous 
encounter with the net by a school. In selecting their grounds, fish- 
ermen rely heavily on past success, visual sightings, observation of 
bird activity, and more recently, on fish-finder sonar equipment. 

The drift net can be described as a floating meshed wall. It is 
maintained in a vertical plane by floats secured to its-head line and 
weights to its bottom line. Small buoys are spaced at intervals along 
the messenger line to indicate direction of lay and presence to surface 
observers. British drift nets average 60 yards in length and 10 to 15 
yards in depth. A single drifter will shoot up to 100 or more nets, 
each joined to the next, forming a continuous wall of netting 3 miles 
long. After shooting her nets, the drifter rides moored to the down- 
wind end until dawn when hauling commences. Mesh size is such 
that fish swimming into the net get partially through before 
becoming hopelessly entangled and held by their gills. Because nets 
are fairly close to the surface and hence visible to schools, all fishing 
must be done at night. 

The foregoing resume of drift net fishing, of course, outlines the 
technique at its highest state of development. Drifting, however, is 
practiced at various stages of refinement throughout the world. Since 
power is not essential to the operation, many less advanced nations 
also utilize this harvesting method successfully using sailing craft 


and even canoes. 
PURSE SEINES 


Purse seines are the most productive harvesting implements 
employed by the pelagic fisheries. Unlike the passive drifting 
technique, purse seining is both active and aggressive with new schools 
continually being ferreted out. A typical purse seine is 2,000 to 3,000 
feet long and 100 to 300 feet deep. The net is hung vertically in a 
circular fashion suspended between a surface float line and a weighted 
foot line. At intervals along the foot line are fastened seine rings, or 
eyes, through which a purse line is rove. Once a school has been 
encircled, the purse line is hauled-in on a power winch thus pursing or 
closing off the bottom escape route. Net sides are then hauled aboard 
the vessel, or into seine boats, until only the heavier bunt section 
remains. This procedure concentrates fish into one portion of the net 
where they can easily be brailed out. 


Loading menhaden from a full sein 


a 


Figure 8 


Purse seining as carried out on the United States Atlantic and 
Gulf coasts is centered around the menhaden fishery. More pounds 
of menhaden than any other single species are harvested annually by 
American fishermen. The 1964 crop was about 1.5 billion pounds. 
Menhaden are an extremely oily fish and except for the roe, which is 
prepared as a salted, frozen or canned product, are not a table fare. 
The meat is generally made into fertilizer and the oil used for industrial 
purposes. Some more highly refined menhaden meal is used in man- 
ufacturing animal and poultry feeds. 

A menhaden purse seiner does not shoot the net herself. After a 
school has been sighted, a striker boat is dispatched to follow the fish 
while the purse boats carrying the net are launched. Using the striker 


37 


boat as a guide, the purse boats quickly proceed to a point ahead of the 
school. There they separate, each carrying half of the net, and circle 
around behind the school. Meanwhile, the striker boat takes up 
station to tend the cork line during net retrieval. Encirclement 
completed, net ends are joined together. Pursing is accomplished by 
throwing a tom weight overboard to which both ends of purse line 
have been attached. Purse boat crews then commence hauling in 
excess net by hand to concentrate fish in the bunt section. The 
seiner maneuvers alongside and brails fish aboard. Figure 8 shows 
a menhaden purse seine set with purse boats hauling in net readying 
catch for brailing. 

Purse seining is the predominant harvesting: technique employed 
by the eastern Pacific tuna, salmon and herring fisheries. Nets in 
these fisheries are normally set directly from the seiner with the 
assistance of a small skiff. Nets are stored on large drums or turn- 
tables located aft to speed shooting time. When a school is sighted, 
the seiner maneuvers to a favorable position and sets one end of net 
into the water. The skiff tends this end and keeps it in position. The 
seiner then proceeds on a circular course to surround the school. After 
completing the set, net ends are joined and net pursed by a deck winch 
aboard the seiner. Figure 9 shows a West Coast drum seiner. 


Figure 9 Photo—U S. Fish and Wildlife Service 


MADI VALAI 


A very unusual and interesting net is the madi valai, or vertically- 
hauled net, used by fishermen off the Madras coast of India. Madi 
valai nets are worked in conjunction with weed lures designed to 
congregate fish over a particluar point. The lures, called kambi, are 
secured to a line having a float at one end and a stone anchor at the 
other. Water currents acting on the float stream the kambi line out 
in an inclined plane. Four catamaran type canoes, each handling one 
of the hauling lines, are paddled into position. Crews lower the madi 
valai horizontally to the desired depth. Next, they position the net 
under the kambi line and haul it rapidly to the surface by hand. Both 
demersal and pelagic species are harvested in this fashion. 


Figure 10 Madi Valai 


SCIENCE AND THE SEA 


SHRIMP FISHERIES 


Coastal regions along the South Atlantic and Gulf coasts of the 
United States are richly endowed with excellent shrimp resources. 
This fishery furnishes more food, employs more people and supports 
a larger packing industry than any other in this geographical area. 
American shrimp fleets also travel far afield, with vessels working off 
Mexico, Honduras, Nicaragua, and Panama. Recently, vast new 
shrimping grounds were discovered off French Guiana. Some author- 
ities believe the area contains the largest unexploited grounds in the 
Western Hemisphere. Estimates of the potential production capability 
have been set at 100,000,000 pounds annually. A new processing plant 
with dockside facilities has been erected at Cayenne, French Guiana, 
to handle the harvest. This plant will process 40,000 pounds of 
shrimp tails daily, and ship them in frozen form to the United States. 

Mexico has a highly-developed shrimp fishery on both her Pacific 
and Gulf coasts. Over 1,000 vessels participate in harvesting the 
Pacific crop, with 300 craft working from Mazaltan, Mexico, alone. 
The east coast fishery is concentrated in the Gulf of Campeche. A 
substantial percentage of Mexico’s rich harvest is imported by the 
United States. 

Australia, Pakistan, Kuwait, and Nigeria are but a few of the 
many nations displaying considerable interest in developing commer- 
cially profitable shrimp fisheries. Any successful fishery must enjoy 
an abundant supply of raw material, adequate processing and storage 
facilities, good transportation connections, and the all important 
markets, domestic or foreign. Pakistan, for example, has a fairly 
abundant supply of shrimp but lacks sufficient local markets and 
distribution facilities. With the aid of modern freezing plants, 
however, Pakistan has been able to develop a good export trade. 

Australia has a young and very promising shrimp fishery under 
development. Authorities, anxious to both expand and conserve the 
fishery, have embarked on a detailed research program to learn more 
about the migration, mating, and feeding habits of shrimp. Through 
such research and close cooperation with the industry, they hope to 
achieve maximum production potential without exploiting the crop 
beyond safe levels. 

Shrimp live on the sea floor and are limited in their distribution 
to areas having muddy or sandy bottoms. With the exception of the 
Royal Red shrimp, which occur in depths between 175 to 300 fathoms, 
they are normally harvested in depths under 50 fathoms. Most shrimp 
caught are in their first year of life. Relatively few ever reach a full 
two year class. This indicates that a severe natural mortality rate 
sets in after the yearlings spawn. It soon becomes evident that a 
highly developed fishery cannot be sustained by a single year class 
without proper crop management. 


— a 


Figure 11 Shrimp trawler 


American shrimp fishermen harvest three major species in the 
southern fishery, which also embraces the Campeche grounds, white 
shrimp, pink shrimp, and brown shrimp. White shrimp are normally 
found in bays and inshore waters under 15 fathoms in depth. Fishing 


38 


for this species is conducted during the day using conventional otter 
trawls having an average mouth opening of 80 to 100 feet. Pink and 
brown shrimp are usually taken in depths of 25 fathoms or more. 
Fishing for these two types is better at night. Vessels engaged in pink 
and brown shrimp fishing use double-rig trawls. Each trawl is 40 to 
45 feet across the mouth, and is towed from an outrigger boom, one on 
each side of the vessel. To-avoid fouling rigs, one trawl trails 150 feet 
behind the other. Double-rig trawls provide better catches, are 
easier to handle, are safer, and suffer less damage than the large, 
single type. 

Before either trawl is streamed a small try-net, with a 10-foot 
mouth, is put over to determine if sufficient shrimp are present to 
make a drag worthwhile. Trawling times vary, but average between 
2 and 3 hours. In addition to the shrimp that are harvested, consid- 
erable trash is picked up. This trash consists of fish, crab, shells, 
sponges, and other unwanted material. After the trawl is dumped on 
deck, the shrimp are removed from the trash, beheaded, and packed 
in crushed ice. The trash is thrown overboard again as no profitable 
means of processing it at sea has yet been found. 


TUNAS 


Tuna fish, or tunny as they are called in many fisheries, are truly 
an international resource, migrating over vast expanses of the tropical 
and subtropical seas. Although tuna fishing is pursued by most 
maritime nations bordering these waters, Japan and the United States 
harvest 90 percent of the world crop. France, Spain, and Peru also 
have very active tuna fisheries. While Japan’s fleets range worldwide, 
the United States effort is concentrated in the eastern Pacific region, 
and around Hawaii. American tuna clippers from west coast ports 
fish from Canada to Peru, occasionally over 500 miles offshore. 

Over a dozen species of tunas are taken by the various world 
fisheries, the five most important being: albacore, yellowfin, bluefin, 
bigeye, and skipjack. Albacore possess the whitest meat hence are the 
most valuable of all catches. 

Harvesting techniques and paraphernalia vary widely. Around 
the Japanese archipelago, live-bait fishing is used for albacore and 
skipjack. Japan’s offshore fleets employ long-line methods. American 
landings are almost entirely by purse seines. In the Bay of Biscay, 
French and Spanish vessels traditionally troll for tuna. Mediterranean 
fishermen still rely heavily on weirs and pound nets for their share 
of the harvest. 

Since both long-line and purse seine fishing have alreadly been 
covered, no additional discussion of those techniques, with regards 
to tuna, will be made. 

Vessels engaging in live-bait tuna fishing must stop after leaving 
port and fish for small sardines, anchovies or smelts. This bait is kept 
alive in large deck tanks by circulating sea water until needed. Large 
clippers carry up to 15 tons of bait per voyage. 

Schools are generally sighted by an experienced lookout stationed 
aloft. Some vessels have expanded their spotting capability by carrying 
a small seaplane, or by hiring free lance pilots working from coastal 
airfields for this chore. Once a school has been intercepted, the 
clipper is positioned and live-bait is thrown overboard to keep the 
school around. All available hands turn to during the ensuing period 
of intense fishing activity to fully exploit the school. 

The crew fish from low-railed platforms secured to hull outside 
the gunwales. Fishing rigs consist of a barbless hook covered with 
feathers called a striker or jig connected by a short stout line to a 
bamboo pole. Excited by the live-bait, the tunas become so voracious 
they seize anything in sight. Upon striking the jig, che tuna is quickly 
pulled from the water and swung over the fisherman’s shoulder, and 
deposited on deck. When fish run large, two, three or even four men 
will work together, each with a separate rod connected by means of a 
swivel to a single hook line. 


TUNNYMEN 


Tunnymen and tuna fishers in European waters bear no resem- 
blance to the more spacious, elaborately equipped, Pacific tuna clippers. 
Vessels engaged in this important fishery off the French and Spanish 
Biscay coast are in the main, either powered craft called pinnaces, 
or large sailing and auxiliary powered yawls and ketches. The latter 
are usually under full sail presenting a picturesque sight with their 
brightly colored sails and hull. The number of these vessels still 
working, however, is small. 

Sailing tunnymen range from 65 to 85 feet in length, carry a 
crew of eight and fish up to 500 miles from their home ports. The 


FISHERIES VESSELS AND GEAR 


key features of sailing tunnymen are their fishing tangons (rods), 
fish drying racks, and absence of a wheelhouse. The two tangons 
are about 50 feet long with slightly curved ends. They are stepped 
by the mainmast, and are a common feature on pinnaces as well. 

Each tangon carries 6 to 8 lines which trail astern of the vessel. 
Additional lines may also be trailed from each quarter. To these 
lines are fastened a brass or iron hook covered with horsehair. Once 
aboard, fish are gutted, cleaned, and hung to dry on rectangular 
framework racks located on deck. Voyages average 14 days on tunny- 
men without refrigeration and 21 days for those having such 
equipment. 

Powered tunny pinnaces operate much closer to their home 
ports, often returning each night with their catch. During the winter 
months many of them fish for sardines along the coast. Vessels range 
from 45 to 60 feet in length. The tangons are stepped near the mast 
which is located aft between the engine room and stern. When not in 
use both tangons are lowered and swung forward to rest atop the 
wheelhouse roof. 

SALMON 


Figure 12 


Wall carvings discovered in French caves bear witness that 
salmon were a popular food resource over 12,000 years ago. Time 
has not altered the salmon’s standing, for today this fish still ranks 
high on the list of most valuable catches. During the space flight of 
Gemini 4, astronaut and seafood connoiseur James McDivitt had 
salmon on his flight menu. The 288 calorie portion was freeze-dried, 
compressed and dehydrated, all of which illustrates the remarkable 
versatility achieved in the processing of this fish. Before eating, the 
astronaut reconstituted his salmon dinner merely by adding water. 

The Atlantic fishery is very small with salmon now considered 
more a game fish than a commercial crop. Once abundant, the great 
decline of the Atlantic stock is due chiefly to negligence. Impassable 
dams, overfishing with nets, industrial pollution and mass destruction 
of seaward-bound young in the water diversions to factories and 
power-plants being the prime causes. 

The heart of the salmon fishery is located in the eastern Pacific 
Ocean, stretching from Alaska to southern California. There are 
five species taken in this prime area. These five, plus a sixth, are also 
found off northern Japan and eastern Russia. The world’s major 
commercial effort is made in these two regions. 

The life-cycle of the Pacific salmon is a most interesting one 
and plays a dominant role in the operation of this fishery. Females 
deposit their eggs in the gravel beds of small fresh water streams or 
lakes which empty into rivers leading to the open sea. After these 
eggs are fertilized by the males, each pair of spawned-out adults die. 
All Pacific salmon die after their single spawning season, while the 
Atlantic species generally return to sea. Throughout the winter, the 
eggs develop with young hatching in early spring. For about two 
months, the young salmon, called fry, live on the yolk sac which 
remains attached to their belly. Once this supply becomes exhausted, 
the fry push their way up through the gravel and become free- 
swimmers. Pink and chum salmon begin their seaward migration 
almost immediately, but the other species generally remain in fresh 
water from 1 to 4 years before migrating to sea. Salmon remain at sea 
from 2 to 5 years, depending on species and latitude, before returning 
to the streams of their birth. Very little is known about their sea years 
other than they scatter widely, and tend to stay in cold water. 


39 


The salmon crop is thus available to the fishery for only a short 
period of time over its entire life span. Fish not harvested during 
the returning migration are lost to the fishery forever, as they will 
all die after spawning. Too many spawners on the grounds can be 
just as detrimental to reproduction as too few. It soon becomes 
apparent that to sustain the species, yet exploit the crop to maximum 
safe levels, all fish over the number needed to reproduce the run 
should be harvested. The problem of determining the number of 
spawners needed is highly complex, and must be calculated for each in- 
dividual stream. Additional spawning grounds can often be made 
available by the construction of fish ladders around obstructions, such 
as dams and waterfalls. 

Salmon are harvested by a wide range of gear with purse seines, 
gill nets, and pound traps accounting for the largest shares. Trolling 
also is widely used in some areas. A typical troller is shown in figure 
12. These vessels range from 25 to 60 feet in length and employ out- 
riggers to keep lines clear of the vessel. In general, the fishing season 
is from late summer to early winter. 


WEIRS, POUND NETS AND TRAPS 


In coastal waters, natural estuaries, inlets and rivers, watch 
officers should always consider the possible danger to safe navigation 
presented by weirs, pound nets and fish traps. 

A weir is an enclosure formed by fences of stakes entwined with 
branches and brush. This type of fishing gear has been used since the 
earliest days of civilization. Weir openings are usually placed some 
distance offshore, in a channel, or between islands to take advantage 
of the natural course taken by migrating schools. Long leaders run- 
ning from shore to the weir’s mouth aid in deflecting fish into the trap. 

The main body is a circular or heart-shaped configuration formed 
by driving poles of various sizes into the sea floor. Brush is then 
closely interwoven between these poles to make the trap escape-proof. 
One or more brush leaders generally extend from shore to a point 
about 6 feet inside the mouth. Mouth openings are just large enough 
to permit fishermen to bring their dories into the trap. Once inside, 
they close off the mouth by means of a small drop net. A seine net, 
rigged in the pocket or crib, is used to concentrate catch for brailing. 
A typical Maine sardine weir is pictured in figure 18. 

Dotting the Malayan shoreline is a very interesting variation of 
the weir called a kelong. These kelongs are fashioned from imported 
Indonesian nebong palm poles. Located offshore, in depths up to 
seven fathoms, they consist of two rows of pole barriers terminating 
at a trap end. Erected directly over the trap end is a sheltered plat- 
form where the fishermen live and work. A net is rigged inside the 
trap and is hauled periodically during the night by means of hand- 
operated winches on the platform. Fish are attracted to the kelong 
by the light from oil lamps which are placed close to the water’s surface 
after dark. As there are no refigeration facilities on the kelong, catches 
are taken ashore each morning. 

Pound nets are similar in many respects to the brush weirs. In 
their simplest design, they consist of three parts: (1) the leader, (2) the 
heart or wings, and (3) the crib. The name “‘pound”’ refers to the 
impounding of fish within the trap. The leader is a wall of netting up 
to 1,000 feet long supported by poles placed at intervals along the 


stakes “ 


Vz 


a 
anchors 


Double heart trap 
with anchors 


Figure 14 Pound net 


SCIENCE AND THE SEA 


route. At the offshore end of the leader, lies the heart, a net enclosure 
about 75 feet across. From the heart, fish enter the crib through the 
gate. Cribs are usually about twice the size of the heart and are made 
of much smaller netting. The crib section has a net bottom which, 
when raised, permits fish to be brailed directly from net to tender. 

Fixed and floating traps may have more than one heart and 
crib, but are basically the same design concept. 


OYSTERS 


The oyster fishery is the oldest of all the known world fisheries. 
Primitive peoples in the earliest days of civilization harvested this 
food resource long before they learned to fish or hunt. Large shell 
mounds called kitchen middens have been found scattered along the 
coasts of Africa, Australia, Europe, and America. The size of these 
mounds indicate the great importance oysters played in the survival 
of these early inhabitants. Today, the oysterman is a true farmer 
carefully tending and cultivating vast underwater tracts. The eco- 
nomic importance is readily appreciated when we find that these sub- 
marine farms often return higher incomes than the best land farms do. 

Oysters are a class of mollusks which have their bodies enclosed 
in a two-valve shell. They have no head and lack the muscular loco- 
motive foot which other members of this group, such as clams, possess. 
Unable to see, hear or move, the oyster must lie motionless on the sea 
floor or attached to some underwater object. To offset the lack of 
vision and hearing, the oyster has developed a remarkable chemical 
sense. Tiny tentacles protrude beyond the edge of the mantle when 
the shell is open to taste the water, and detect light changes. A 
sudden change in light, or the presence of a toxic material in the water 
will cause the tentacles to contract. The stimulus of this action is 
passed through the mantle to the adductor muscle and the shell is 
closed. A tightly closed shell is the oyster’s only means of defense. 


LOBSTER FISHERIES 


The delicacy of lobster meat and their high value per pound are 
valid barometers of the importance of this fishery. Disregarding minor 
specie differences, lobsters can be broadly classed as either true 
lobsters or spiny lobsters. The key distinguishing features of the true 
or Maine lobster are their large heavy crushing claws, stiff tail fan 
and smooth dark green body shell. This class is concentrated along the 
New England and Canadian coast. 

Spiny lobsters have a much broarder range of distribution being 
found in the warmer coastal waters throughout the world. As the 
name implies, the legs and body shell are covered with short spines. 
Lacking the large crushing claws of the true lobster, only the tail 
section of the spiny lobster is worth processing. 

South Africa is the world’s largest spiny lobster producer. 
Australia, New Zealand, Japan and the West Indies also harvest a 
large crop of spiny lobsters annually, many of which are exported in 


frozen form. Commercial harvesting of all lobsters centers around 
the use of pots or traps. Although a wide variety of sizes, shapes and 
construction materials are to be found, the principle remains the 


same. 


Figure 15 Lobster pot 


oe 


A typical New England trap consists of an oblong lath box 
weighted with brick or stone and having one or two funnel-shaped 
openings. Bait, in the form of decaying fish, is hung inside the trap 
and acts to lure the lobsters in. While the bait last, the lobsters seem 
content to stay, but once gone, they are often able to escape the trap. 
For this reason, traps are hauled daily, if possible. 

Most lobsters are caught in less than 30 fathoms of water. Buoys 
bearing the distinctive colored marking of the owner, are secured by 
warps to the traps, making identification easy. A single lobsterman 
can usually handle 100 traps under normal conditions. 


CONCLUSION 


It has been established that fishing is as old as man himself and 
that the paraphernalia employed to harvest the crop is infinite. The 
development of any commercial fishery is dependent upon a sustained 
demand, the physical properties of the sea, an abundant resource, a 
means of gathering, a mode of transport, and adequate storage. 
Regardless of how primitive or how sophisticated the endeavor, it is 
predicated on one of three basic techniques: direct attack, snaring, 
or luring. Further, each fishery requires either special vessels, gear or 
both to fulfill its mission. Finally, and perhaps most important, for 
any fishery to survive at a profitable level, some form of intelligent 
conservation program must be inaugurated. 

Armed with this basic understanding of fishery operations, 
professional seamen can be expected to do more to make all encounters 
with the vessels, men and gear of this industry safe. 


PS OF OPPORTUNITY 


By F. W. Fricker 
Maritime Safety Division 
U.S. Naval Oceanographic Office 


During the past year or more, a number of scientific and mari- 
time-oriented news media have made repeated references to the term 
“ships-of-opportunity”. They were, of course, referring generally 
to those instruments of a unique method being recently employed 
by a number of agencies to conduct scientific research in the open 
ocean; the ships of the merchant marine. 

The sudden surge of publicity in this regard was undoubtedly 
stimulated by two recent incidents which captured the imagination 
of the scientific press, aroused the interest of marine scientists, and 
attracted the attention of a segment, at least, of the U.S. Congress. 
Early in 1965 the U.S. Naval Oceanographic Office revealed plans 
to employ ships of commercial lines to gather oceanographic data, 
and the Office of Naval Research announced the successful comple- 
tion of their PROJECT NEPTUNE. Although the primary objec- 
tives of the two projects were unrelated, the ships designated for 
participation became unofficially, yet appropriately, known as “ships- 
of-opportunity”. 

The origin of this, perhaps unusual, sobriquet is obscure. It can, 
however, be traced as far back as 1959 when additional ocean-going 
platforms were sought to assist naval units in support of a project 
the Navy calls ASWEPS (Antisubmarine Warfare Environmental 
Prediction Services). The pro3=ct involved the development of thermal 


BATHYTHERMOGRAPH LOG 


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41 


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structure forecasting techniques in support of antisubmarine warfare 
operations, and was logically assigned to the Naval Oceanographic 
Office. That Office initiated a reporting system which consisted of 
a network of ships in the western North Atlantic Ocean. In addition 
to the conventional survey ships, all properly equipped naval vessels 
were directed to participate in the program. These units were later 
joined by U.S. Coast Guard vessels and ships of the Canadian Navy. 

In order to increase the number of participating ships in the net- 
work, the Military Sea Transportation Service (MSTS )was requested 
to cooperate. That agency responded by making their large fleet 
available for the purpose, and their worldwide operations permitted 
a wide choice of platforms from which to fashion a more formidable 
network. 

It is not clear to which category in this succession the title 
became attached, but due to the limitations imposed by schedules, 
routes, etc. of the latter group it can be surmised that MSTS ships 
were the first to be called “ships-of-opportunity”. 

The majority of the newcomers to the program were civilian- 
manned. Some were, for all practical purposes, purely merchant 
ships, being attached to the parent service by virtue of a charter. 
It is not surprising, therefore, that today the term has come to mean 
only those scheduled commercial and MSTS ships selected through 
expediency to perform oceanographic research. This context was 
further strengthened by the forementioned PROJECT NEPTUNE, 
sponsored by the Office of Naval Research primarily to demonstrate 
the feasibility of using merchant ships to collect biological samples 
in the vast reaches of the oceans. 


SCIENCE AND THE SEA 


In addition to being a name used to identify participating 
vessels, however, the title “ships-of-opportunity” is now thought of 
as embracing the entire concept of merchant ship utilization for 
oceanographic research purposes. The main feature of this unique 
means of obtaining scientific data that distinguishes it from regular 
programs is the specification that the acquisition thereof is not to 
interfere with the primary mission of the vessels involved. While 
this element naturally imposes certain limitations on the type of re- 
search that can be conducted, experience has shown that a number 
of worthwhile programs can be tailored to fit the restrictions im- 
posed by the fixed route, high speed, and shipboard routine character- 
istic of merchant ship operations. Perhaps more importantly, the 
preciseness of berth liner schedules and their steadfast adherence to 
known routes present the scientific community with an unprecedented 
opportunity to plan and conduct a variety of research over the sea- 
lanes of the world. Indeed, it is this very singularity of purpose 
peculiar to merchant ships which provides the researchers with a 
simplex base from which to plan and outfit an expedition. 

Because of the variety of studies involved in oceanographic re- 
search, ships -of- opportunity can mean different things to different 
people. Depending upon the aspirations of sponsoring groups, the 
types of research conducted in this manner and the techniques em- 
ployed can vary from ship to ship. One or more programs can be 
conducted from a single ship, utilizing gear supplied by the researcher, 
or ship’s equipment. The observations can be made by scientists 
embarked for the purpose or by previously indoctrinated members 
of the ship’s personnel. Moreover, the data collected cculd be im- 
mediately processed and recorded in mobile laboratories temporarily 
deck-loaded or codified and radioed to specified receiving stations. 
Undoubtedly, other variations can be introduced to meet the require- 
ments of many research projects. 

The obvious flexibility of research activities permitted under this 
program is one of its more attractive aspects. It offers, at least, 
limited oceanic research capabilities to the many institutions now 
engaged in oceanographic work. It could provide them, at least 
theoretically, with an additional means of acquiring the special data 
they desire, and lessen their dependence upon other research facilities 
for needed information. As a companion benefit, any large usage of 
ships-of-opportunity would lighten the tremendous burden of routine 
survey and data collection responsibilities now imposed on our 
harried research vessels. 

Probably the most attractive aspect of using ships-of-opportunity 
as oceanographic platforms is the relatively low cost per scientific 
observation that can be realized. This feature is afforded by the 
fact that the vessel’s operating costs are covered by the steamship 
company responsible whether or not any research is conducted aboard. 
By comparison, all costs involved in the operation of a special 
research or survey ship must figure into the average cost-per- 
observation, and as a result, that cost is considerably higher. 
Another significant monetary saving is that which could be realized 
if scientific institutions were relieved of the outlay of funding the 
design, construction, and maintenance of numerous oceanographic 
research vessels. Under the ships-of-opportunity concept, these 
costs are defrayed by the merchant ship owners and operators. About 
the only financial responsibility to be met by the scientific com- 
munity would be in designing, procuring and maintaining the 
scientific equipment used; transporting it to the ships; and paying 
the usual ocean freight charges, passenger expenses, and whatever 
shipboard labor costs that are incurred. 


BORN OF NECESSITY 


The concept of utilizing unconventional ships for oceanic data 
collection grew out of the need to augment the nation’s research 
capabilities. The last two decades have witnessed a fantastic in- 
crease of scientific interest in the marine environment, as well as 
technological enthusiasm in exploiting oceanic resources. The in- 
crease has been understandably accompanied by a growing demand 
for field data. In addition to the extensive government sponsored 
programs, such as ASWEPS, many private institutions, both large 
and small, have become increasingly involved in oceanographic 
research. As their programs expand, new avenues of study come 
into focus which require precise field data for development; data 
which can only be provided by ocean-going platforms. 


42 


The demand for similar facilities is further heightened by the 
recently awakened interest in the marine environment by a growing 
number of scientists in so-called “non-oceanographic” fields, such as 
aquatic biology and biomedical physics. 

For the most part, the burden of data collection in the open ocean 
has fallen to our comparatively small fleet of specialized research 
ships. In spite of several recent additions, augmentation of that 
fleet has not been proportionate to the demands for its service. 
Future increases in the size of the fleet will be limited due to existing 
budgetary restrictions. If we, as a nation, are to realize the antici- 
pated development of our oceanographic programs, we must keep 
pace with the expanding requirements of its many components. The 
ships-of-opportunity program appears to offer one of the more likely 
means of attaining that goal. 


NOT A NEW IDEA 


Although the title "ships-of-opportunity” is a relatively new one, 
the concept of using the deck of a merchant ship from which to per- 
form scientific experiments dates back to antiquity. Many of the 
early students of astronomy availed themselves of the observations 
made aboard trading vessels. Prior to the American Revolution, 
Benjamin Franklin took advantage of time spent upon merchant 
ships to personally investigate the Gulf Stream. One can well imagine 
the cooperative enthusiasm that this personable genius inspired 
among the ship’s crew. His studies resulted in the printing of a chart 
showing the width, course, and speed of that current which was re- 
markably accurate for its time. Furthermore, his sampling and 
study of the “phosphorescent waters” led him to support the then 
revolutionary theory that the phenomenon was organically induced. 

The exploits of Matthew Fontaine Maury are well known. 
Probably no scientist has ever utilized the observations made by 
mariners with greater results. Without the aid of a single survey 
vessel, his systematic examination and analyses of meteorological 
and hydrographic data recorded in myriad log books led to the genesis 
of a series of wind and current charts which were to revolutionize 
the world’s trade routes. His “Abstract Logs”, conceived and pre- 
pared by Maury to enable mariners to tabulate their observations. 
were the forerunner of the forms used by today’s cooperating 
observers. 

Perhaps even the work of Nathaniel Bowditch can also be in- 
cluded in this recap for although his computations were solely the 
result of his remarkable mind, Captain Bowditch availed himself of 
his crew’s willingness to learn and thus was able to gear his classic 
navigational solutions to the intellect of the average seaman. 

The U.S. Weather Bureau has utilized the ships-of-opportunity 
concept for more than 60 years in fostering the growth of a network 
of cooperative weather reporting ships. Today, the synoptic data 
received from their network, which includes many foreign flag 
vessels, enables the Weather Bureau to broadcast advisories and 
transmit weather charts by facsimile. 

The direction and speed of ocean currents shown on Pilot Charts 
and in Current Atlases, particularly those not associated with the 
general circulation and those influenced by tidal action, have been 
determined over the years largely from drift and set information 
submitted by cooperating mariners. 

Thus, the research work begun by the far-seeing marine scientists 
of the past, made possible only by the cooperation of the mariners 
themselves, has provided us today with a sound background upon 
which to model and extend a productive ships-of-opportunity program. 
With a heritage such as this, the introduction of the scientist and 
his tools aboard modern merchantmen should prove of no hardship 
to the traditionally adaptable merchant seaman. 


ASWEPS 

In addition to the commercial and academic applications of 
synoptic oceanographic data, there is another, and perhaps more 
urgent, requirement. Scientists have long been aware that Sonar 
transmission can be deflected by water layers of differing tempera- 
tures, salinities, and/or densities, a phenomenon which affords sub- 
marines a distinct advantage over their surface adversaries. To reduce 
this advantage in favor of our antisubmarine forces, the U.S. Navy, 
under the coordination of its Oceanographic Office, established 
the Antisubmarine Warfare Environmental Prediction Services 
(ASWEPS) in 1959. The program was, and still is, experimental, its 


SHIPS-OF-OPPORTUNITY 


main purpose being to develop techniques in forecasting the ever- 
changing thermal structure of the sea. The area of the ASWEPS 
experiment was initially restricted to the western North Atlantic 
Ocean, but it has gradually been extended to include the eastern 
North Atlantic Ocean, Mediterranean Sea, and the Pacific Ocean. 

At the outset, it was determined that ASWEPS development 
depended, to a large extent, on the regular receipt of oceanographic 
data, temperature-versus-depth information being the single most 
important environmental parameter required. To help meet this 
important temperature profile requirement, the Naval Oceanographic 
Office set up a network of reporting ships which consisted of the 
approximately 500 U.S. Navy ships that had previously been equipped 
to make bathythermograph (BT) observations. They were directed 
to make BT observations 4 times each day and transmit the results 
to the Naval Oceanographic Office for analysis. A composite of the 
data received has been used, as planned, for the preparation of 
synoptic sea surface temperature, sonic layer depth, and vertical 
gradient charts which are transmitted to the fleet and others by 
facsimile broadcast, similar to weather charts, or by radio message. 
These data have also been applied to the development of thermal 
structure forecasting techniques. 

It was soon evident that the quantity and distribution of the data 
being reported was inadequate to provide the synoptic picture desired. 
Accordingly, a program was established to fill the data gap by 
utilizing various ships-of-opportunity, in this case, any vessels with 
a BT capability that were willing to participate. The first agency 


to cooperate in the program was the U.S. Coast Guard, but shortly 
thereafter the Bureau of Commercial Fisheries, the U.S. Coast and 
Geodetic Survey, various private institutions, and foreign govern- 
ments were also cooperating. 


ELMIDB codulds 


To increase the efficiency of the reporting network, a study was 
conducted to determine the feasibility of installing BT equipments on 
Civil Service manned ships of the Military Sea Transportation Service 
The study, begun in May 1959, proved extremely successful. Four 
MSTS passenger ships and one MSTS cargo ship operating routinely 
between New York and northern Europe were equipped with a BT- 
collecting capability. The Civil Service crews in these ships obtained 
and transmitted BT observations twice daily, when operating outside 
the 100-fathom curve, without any deleterious effect on the ship’s 
primary mission. These ships increased the area of BT coverage by 
collecting their data along the sea lanes to and from Europe, thereby 
providing a dependable data input in areas where Fleet ships seldom 
operated. 

As a result of the success of this venture, additional MSTS ships 
in both the Atlantic and Pacific Oceans have been BT equipped. As 
of July 1 of this year 28 MSTS ships were regularly collecting and 
reporting BT data. 


SS 


43 


Various other governmental agencies and educational institu- 
tions operating survey vessels throughout the world were invited to 
participate in the program. Most of the organizations contacted 
responded favorably and are cooperating faithfully. 

To effectively accomodate the expanding activities of ASWEPS, 
additional analysis groups were established. In October 1962, a 
Regional Analysis Group was initiated under the auspices of Naval 
Weather Service at Fleet Weather Central, Guam. Then, in January 
1964, the Pilot ASWEPS (PASWEPS) Centre was established in 
London by the British Admiralty (now Hydrographic Department, 
Ministry of Defence). This year, additional analysis centers have 
been established in Rota, Spain; Pearl Harbor, Hawaii; and Alameda, 
California. 

The initiation of the analysis system at Guam precipitated the 
idea of soliciting the cooperation of all friendly nations operating 
BT-equipped ships in the western North Pacific. As a result, BT 
data is now being received from Australian, British, Hong Kong, 
Japanese, Korean, and New Zealand ships operating in that area. 

Nations operating Ocean Station Vessels in the eastern North 
Atlantic PASWEPS area regularly transmit reports to the central in 
London. These participating countries, besides the United Kingdom, 
include Denmark, the Netherlands, Norway, and France. 


Ae e 
a " > 


In May 1959 the USNS GEN. WILLIAM O. DARBY was BT-equipped 
and commenced reporting into synoptic network. 


Despite the apparent size of the growing network, the amount 
of BT data received daily remained inadequate for conclusive analyses 
of the sea’s thermal structure. Pursuant to the primary objective of 
the program, the search for potential BT data platforms continued. 
For all practical purposes, the only extensive source of ocean-going 
platforms that remained untapped for oceanographic data collection 
was that of the commercial maritime industry. 

More than 18,000 commercial vessels of over 1,000 gross tons now 
ply the world’s oceans, 900 of which fly the American flag and many 
more are American owned. While the concept of utilizing these 
vessels for oceanographic data collection had been discussed for years, 
little or no organized effort had been made to exploit this source. 

A study was initiated by this Office to determine what improve- 
ment could be made in the synoptic data distribution by utilizing 
these ships-of-opportunity. By simulating a plot of selected mer- 
chant ships embarked on scheduled voyages and assuming that they 
were reporting BT data at prescribed intervals, a marked improve- 
ment in the distribution of synoptic data was theoretically achieved 
throughout the network. 

Encouraged by the results of the study, the Naval Oceanographic 
Office issued a proposal through the American Merchant Marine 
Institute for commercial steamship companies to participate in a 
pilot project to determine the feasibility of employing commercial 
ships for the acquisition of BT data. The pilot project would involve 


SCIENCE AND THE SEA 


the outfitting, training, and evaluation of five or six commercial 
ships. It was specified that participation in the BT program was 
not to interfere with the primary mission of the ship. 

The proposal, still valid, states that participation entails the in- 
stallation of a 515 pound hoist on the port or starboard quarter of the 
ship the precise location being determined by the shipowner. The 
hoist drum is designed to hold 3,000 feet of 3/32-inch stainless steel 
wire rope. Further installation includes a 10-foot retractable boom 
which is fastened to the rail adjacent to the hoist. A supply of 2 
bathythermographs, each a torpedo-shaped mechanical instrument 
weighing about 40 pounds, will be maintained aboard ship. All costs 
related to the installation, fabrication, supply, and calibration of the 
equipment are borne by the U.S. Navy. 

Since the project is predicated on the ship’s personnel operating 
the equipment, a representative of the Naval Oceanographic Office 
boards each ship to indoctrinate the crew in the program and ex- 
plains the methods of recording, interpreting, and transmitting the 
BT data. A minimum of three days deep sea steaming time is re- 
quired for training. 

The procedure to be followed by the crew members assigned is 
quite simple. BT observations can be taken at speeds up to 16 knots. 
An observation is to be made twice daily at 0800-0900 and 1600-1700 
local time when the ship is operating north of the Equator in depths 
greater than 100 fathoms. The launching and retrieving operation 
requires 2 men for a total of approximately 10 minutes. A glass 
slide, inserted in the BT prior to each observation, is etched with a 
permanent trace of temperature versus depth. Upon retrieval, the 
slide is placed in a viewer, the data recorded in a BT log book, and a 
coded message drafted. Logging the information and drafting the 
message requires about 10 minutes. The coded message (BATHY) 
is similar to a weather message and is transmitted to an appropriate 
analysis center during a normal radio watch as soon as possible after 
the observation is made. Accumulated BT log sheets and slides are 
mailed to the National Oceanographic Data Center, Washington, D. C., 
upon each return to the continental United States. 

The maritime industry’s response to the proposal was immediate. 
The first sucessful contract for the utilization of ships of a com- 
mercial line in the BATHY network was inaugurated on 1 February 
1965 and soon thereafter the SS African Rainbow became the first 
of a new class of ships-of-opportunity. As of July 1, 1966, eight 
additional ships have been integrated into the ASWEPS system, and 
are reporting BT data as part of their daily routine. 


NAVOCEANO representative, holding the torpedo shaped bathy- 
thermograph, travelled aboard the AFRICAN RAINBOW from New 
York to the Canary Islands to collect data and train the ship's 
personnel on the proper operation of this device. 


THE NEAR SURFACE REFERENCE 
TEMPERATURE SYSTEM 


The procedure of taking and recording sea water temperatures 
is practically as traditional aboard ship as relieving the watch. The 
measurement is an important part of the weather reports submitted 
by weather reporting ships. It is a routine entry in the engineering 
log book. Survey vessels use sea surface temperature as a reference 


44 


value in bathythermograph observations. Ship’s officers are re- 
quested to include it when reporting on observed phenomenon to this 
Office. In short, the temperature of the sea has long been of scientific 
importance. 

Sea surface temperature observations, when regularly received 
from a dense network of reporting platforms, can be used to construct 
sea surface temperature charts which have a number of important 
applications. In addition to the military aspect, surface temperature 
charts are now being utilized by the fishing industry to predict the 
shoaling behavior of certain popular fish, such as tuna and salmon. 


Photos—courtesy Texaco Inc 


Crewmen taking BT measurements aboard the TEXACO NEW JERSEY, 


SHIPS-OF-OPPORTUNITY 


As an example of this application, the U.S. Bureau of Commercial 
Fisheries publishes such a chart showing a 15-day synopsis of surface 
temperatures along the west coast of the United States. 

Unfortunately, the majority of surface temperature measure- 
ments reported by ships are generally obtained from the ship’s intake 
thermometer, an instrument of questionable value for measuring sea 
surface temperatures. The World Meteorological Organization, 
Commission for Instruments and Methods of Observation (1957), con- 
cluded that “intake temperatures suffer from lack of proper location 
of the thermometer, from unsatisfactory thermometers, and from 
crudeness (sic) of reading or timing”. 

To improve the quality of reported sea surface temperatures, the 
Naval Oceanographic Office conducted extensive tests in the labora- 
tory and in the field to determine the effectiveness of various sea 
surface temperature measuring devices. The tests consisted of a 
comparative analysis of the classical devices and a newly developed 
device now commonly known as the Near Surface Reference Tem- 
perature (NSRT) System. The new device consists of a thermistor 
probe installed in the intake and electrically connected to a tempera- 
ture indicating meter on the bridge. (See below.) Instantaneous 
measurements of surface temperatures can be obtained by merely 
depressing a button, thus permitting the watch officer to make 
the reading. The intake probe and meter readout proved espe- 
cially promising from the standpoint of dependability, accuracy, 
and convenience. 


I SS 


NSRT—Near Surface Reference Temperature meter and thermistor probe. 


In late 1964, the U.S. Naval Oceanographic Office, in connection 
with ASWEPS, invited the U.S. Weather Bureau, Coast Guard, 
MSTS, and the Fleet to install and operate 125 systems. Upon com- 
pletion of this pilot program, installations will have been accom- 
plished on proportionate numbers of Coast Guard vessels, cargo and 
tank vessels of the MSTS, destroyers and aircraft carriers of the 
Fleet, commercial ships participating in the U.S. Weather Bureau 
cooperative weather reporting program, and several oceanographic 
research vessels. This wide variety of sea-going platforms is truly 
representative of the modern concept of ships-of-opportunity. 

Experience gained in connection with the NSRT program will be 
used as the basis for further standardization of equipment and tech- 
niques. Meanwhile, shipboard personnel will appreciate the NSRT’s 
capability for accuracy and the ease with which the observation can 
be made. 

In addition to the observations required by the synoptic network, 
selected ships-of-opportunity having the necessary sounding equip- 
ment have been requested to record the depth and thickness of the 
Deep Scattering Layers wherever encountered. The data thus accu- 


45 


mulated is forwarded to the Naval Research Laboratory for analysis 
in conjunction with their continuing studies of that biological-induced 
phenomenon. 


PROJECT NEPTUNE 


On October 19, 1964, the 8,000 ton American Mail Lines freighter, 
the SS Java Mail, departed Seattle, Washington, bound for Yokohama, 
Hong Kong, and other ports in the Pacific and Far East. From all 
appearances, the ship was embarked on a routine voyage. She was 
laden with a cargo consigned for another continent, and her officers 
and crew went about their work just as they had on many previous 
voyages. On this occasion, however, a Navy trailer van was lashed 
to the after deck and a six-man scientific party was berthed in the 
ship’s cabins. Quite incidental to her task of delivering her cargo 
to foreign ports, the Java Mail was participating in the U.S. Navy's 
PROJECT NEPTUNE. 

PROJECT NEPTUNE was executed to determine the feasibility 
of collecting biological oceanographic research data from a merchant 
ship without interferring with the routine of the ship’s operation. 
By this singular demonstration, the Office of Naval Research, 
sponsor of the undertaking, hoped to establish the practicability of 
the concept of a fleet of “research ships-of-opportunity” (RSO’s), 
specifically, ships of the American Merchant Marine. The project 
was the culmination of NRL’s long standing desire to prove that con- 
cept and brought together the interests and resources of the General 
Motors Defense Research Laboratory which developed special sam- 
pling devices for the experiments; the Naval Missile Center at Point 
Mugu, California, which provided the laboratory van; and the 
American Mail Lines, which arranged for the Java Mail to serve as 
the first experimental RSO. In addition, PROJECT NEPTUNE 
received considerable encouragement from members of the staff of 
Congressional committees concerned with oceanography, particularly 
the House Committee on Merchant Marine and Fisheries. 

This particular variation of the ships-of-opportunity concept 
features the deployment of a mobile laboratory with a team of on- 
board scientists to perform all of the duties connected with the 
scientific mission. The latter element is to enforce the “not-to- 
interfere” principle of the original idea. The mobile laboratories 
designed for RSO’s could be stored at central or regional depots. 
When needed, any appropriate group of scientists could rent, lease, 
or charter one or more from the depot and arrange to have them 
transported to the port where the selected RSO is docked. The 
laboratory unit would then be hoisted aboard the ship and either 
fastened to the deck or placed in a hold, as appropriate. When 
necessary, the unit would draw upon ship’s power and utilities, 
although, preferably, each laboratory would be a self-contained unit, 
independently powered. The scientists and technicians accompanying 
the laboratory would utilize the tourist accomodations of the host 
ship. 

Demonstrating as many of these basic conditions as possible, the 
Java Mail proceeded upon her scheduled voyage. During its Pacific 
crossing, the vessel served as a platform for a variety of oceanographic 
investigations. Plankton samples were taken with a “jet-net”, a 
bullet-shaped pod specially designed to collect undamaged specimens 
at the surface of the ocean while being towed at a relatively high 
speed. The vessel’s main injection was used to take plankton 
samples and record sea water temperatures. Three times a day the 
group obtained bathythermograph data to a depth of 1,500 feet 
utilizing an experimental high-speed expendable bathythermograph. 
A thermistor was towed astern which measured water temperature 
continuously. Continuous atmospheric samples were taken recording 
radiations and other values. Water analyses were made to ascertain 
salinity, chemical composition, and oxygen content. Disposable radio 
transmitters were put into the sea and tracked periodically. Finally, 
drift bottles were cast overboard every eight hours. 

The results of all tests and samplings were quite encouraging. 
By the time the Java Mail arrived at Hong Kong, all scientists 
aboard were completely convinced that the project was a great 
success and that the use of a merchant vessel for oceanographic 
work was entirely feasible. 

On 22 January 1965, the House of Representatives Subcommittee 
on Oceanography of the Committee on Merchant Marine and Fisheries 
met in Washington, D.C. The purpose of the meeting was to 
bring together the oceanographic interests of the government and 
industry to hear, first hand, the results of PROJECT NEPTUNE and 


SCIENCE AND THE SEA 


to evaluate, generally, the ships-of-opportunity program. At adjourn- 
ment one thing was apparent: the nation’s legislative, scientific, and 
industrial leaders involved in oceanography were in complete accord 
that the ships-of-opportunity concept was sound. 

In July 1965, a further experiment in PROJECT NEPTUNE was 
carried out in the Atlantic Ocean, utilizing the SS Export Champion 
of the American Export-Isbrandtsen Lines on its New York-Rota- 
Genoa run. A mobile laboratory was transported to the departure 
point, in this case, New York Harbor, secured aboard with the aid of 
Naval Oceanographic Office and General Motors technicians, and in 
less than 48 hours the vessel sailed with an operating unit of five 
persons embarked. During the voyage, two types of expendable 
BTs were successfully streamed, the BT data acquired being sent to 
Fleet Weather Central, Rota, Spain. General Motors had installed 
a device that directly digitized the input onto a radio-teletype tape, 
to the dismay of F WC, Rota, which had not expected a merchant 
vessel to possess this capability. The high-speed net tow (jet-net) 
was damaged during the Atlantic crossing by being pulled against 
the ship’s side by propeller action. It was rebuilt in Rota and suc- 
cessfully operated on the Rota-Genoa run. The continuous recording 
water temperature probe unit (NSRT) installed, by NAVOCEANO 
operated successfully throughout the cruise. 

PROJECT NEPTUNE, Atlantic, was considered by project 
officials to be a definite success in demonstrating that oceanographic 
units can be quickly mounted aboard merchant ships with little in- 
port installation time and no shake-down, and that the basic sensors 
can operate at 19 knots across an entire ocean without interfering 
with a ship’s normal operating procedure. 

In another experiment, the Department of Interior’s Bureau of 
Commercial Fisheries instigated a 14-month test project utilizing 
the Matson Navigation Company’s SS Californian as a ship-of- 
opportunity. Using an expendable device, crew members of the 
Californian obtain temperature data every 6 hours to a depth of 
1,500 feet along its track from Honolulu to San Francisco. These data 
are of interest to oceanographers in general and of vital concern to 
the Bureau of Commercial Fisheries in its study of the seasonal 
and year-to-year variations of the California Current region. Here, 
in an area that was once an opulent sardine fishery, large quantities 
of albacore, salmon, mackeral, bluefin tuna, and game fishes are 
taken each year, and major resources such as anchovy and hake exist 
untapped. Proper monitoring of the environment will be an important 
element in assuring that these resources may be utilized now, yet 
maintained for future generations to exploit. The success of this 
experiment will undoubtedly encourage a further and more extensive 
use of ships-of-opportunity for fishery research. 


DISCUSSION 


The cumulative successes achieved during these modest experi- 
ments with unorthodox research platforms has assuredly earned a 
place for the merchant ship in all future programming of the nation’s 
oceanographic effort. Even at this relatively early stage of develop- 
ment, the theory that ships-of-opportunity can greatly expand our 
oceanic research capabilities has been soundly proven. A post 
analysis of their accomplishments thus far shows that valuable raw 
data concerning the sea’s thermal structure can be provided by these 
ships over large portions of the oceans. Viable specimens of surface 
organisms can be taken at relatively high speeds with the prototype 
jet-net, and surface waters can be analyzed for almost any parameter 
known. The most surprising aspect of the several programs 
attempted is that this much has been achieved, for the most part, 
with “on-the-shelf”, practically obsolete, instrumentation. 

Because of the lack of more sophiscated instrumentation, the 
ships-of-opportunity programs are, at the present time, severely 
restricted in the types of observations they can make. In the case 
of the bathythermograph program, expansion of the network utilizing 
ships-of-opportunity has one serious limitation. A ship must slow 
to approximately 12 to 16 knots for 15 to 20 minutes while streaming 
a bathythermograph. The number of American Flag commercial 
ships operating at the low speeds acceptable for mechanical BT 
observing is at present very small and decreasing steadily each year. 
Furthermore, available MSTS platforms will have been exhausted 
in the near future. Therefore, if the Naval Oceanographic Office 
is to continue to engage in a vigorous BATHY Network expansion 
program, a capability must be developed to enable vessels to make 


46 


BT observations at speeds up to 30 knots. Accordingly, utilization 
of an expendable BT system is being planned for ships-of-opportunity 
beginning in Fiscal Year 1968. This system should make the entire 
American Flag fleet of approximately 900 ships available as potential 
synoptic network participants. 

In spite of the amazing successes in recovering biological 
samples at high speed, there are no readily available instruments 
that can duplicate the feat at any significant depth. The Near 
Surface Reference Temperature (NSRT) System, now being installed 
on many participating ships, will provide a vast improvement in a 
synopsis of surface temperatures throughout a given network of 
ships. The system is, however, still in an experimental stage which 
will preclude, for the present, mass production of the instruments 
involved. The expendable bathythermographs, types of which 
everal manufacturers have introduced, are, at the present time, 
capable of measuring temperatures to a depth of only 1,500 feet. 


Para-Buoy. 

Airborne instruments such as the ART (Airborne Radiation 
Thermometer) and the AXBT (Airborne Expendable Bathythermo- 
graph) have been developed and employed on an experimental basis, 
adding the element of great mobility to the synoptic coverage of the 
oceans. Here again, the high cost of instrumentation may prohibit 
the immediate use of large numbers of aircraft for observational 
purposes. 


It is generally conceded by all concerned that inadequacies exist 
in the synoptic type oceanographic data currently available for both 
research and development and operational analyses and forecasting. 
They can be summarized as follows: 

(a) Insufficient number of observations. 

(b) Inadequate distribution of data points. 

(c) Variations in instruments, exposure, and observational 

procedure. 

(d) Crude and inaccurate instrumentation. 

(e) Limitations in acquiring certain required observations. 

(f) Locating error in navigation. 


Some of these inadequacies will eventually be resolved as a re- 
sult of instrumentation development now underway and planned. 
When available, new instruments will result in greater accuracy of 
observation and permit acquisition of additional required parameters 
such as salinity and sound velocity of the marine environment at 
greater and greater depths. Standardization of instruments such as 
the NSRT and the expendable BT will refine the quality of data 


Above—Special winch for 


Right —S. S. AFRICAN 


SHIPS-OF-OPPORTUNITY 


by improving instrument exposure and observational procedure. 
Eventually, the use of navigational satellites will reduce the data 
positioning problem. 

With the possible exception of moored oceanographic platforms 
(buoys) still being developed, and the planned employment of air- 
craft for synoptic observations, none of the above efforts is directed 
toward solving the problem of inadequate data distribution. The 
efforts directed toward enhancing data accuracy and sensing addi- 
tional elements may, in fact, deter solving the data distribution 
dilemma for at least the immediate future, because of the great unit 
cost often related to instrumentation development. As an example, 
the STD (salinity-temperature-depth) System being developed under 
the ASWEPS program will provide more data, with greater accuracy 
and at greater depths than now possible. Because of the relatively 
high cost plus installation and upkeep, however, the output from this 
instrument development will be limited to four data points in the 
North Atlantic for, at least, the near future. Present plans for 
utilization of the expendable BT’s indicate that about 32 platforms 
will be outfitted and approximately 22,500 units expended during 
1966. Here again, the expendable BT’s will replace the mechani- 
cal BT on Fleet ships with no significant improvement in data 
distribution. 

The data location or navigation problem is an inherent limiting 
factor in any ships-of-opportunity program. Most of the commercial 
ships available for this program employ LORAN A for navigation. 
Under normal operations at sea, LORAN is utilized only within 
several hundred miles of the coast, so that in mid-ocean greater 
errors than the optimum are common. From all indications, even new 
construction has made few provisions for precise positioning devices. 
It is also doubtful that commercial ships will convert to navigational 
satellite systems to any great degree in the next decade. 

A program involving the development of highly accurate (and 
highly expensive) oceanographic instrumentation for employment 
on platforms which cannot provide companion accuracy in data 
location may not be realistic. 


handling bathy- 
thermograph. 


RAINBOW, first of 
a new class of 
Ships-of-Opportu- 
nity. 


Photos—courtesy Farrell Lines 


47 


Therefore, the ships-of-opportunity program over the next few 
years must concentrate on synoptic data distribution. This is not 
meant to imply that ultimate data accuracy and instrument sophisti- 
cation is not required. In the immediate future, while instrument 
availability and costs of sophisticated instrumentation are limiting 
to mass distribution, considerable advantage can be gained in 
developmental forecasting by utilizing less refined (and less ex- 
pensive) gear to obtain wide data distribution at frequent intervals. 
Implementation of this concept will undoubtedly see a greater and 
greater expansion of the commercial fleet of ships-of-opportunity. 

Once the necessary instruments become available in the quantity 
desired, the number of potential ships-of-opportunity can be equated 
to the number of U.S. Flag and, perhaps, U.S. owned merchant 
ships. With this vast fleet theoretically at our disposal at some 
future date, definite plans for its utilization are now being made. 
The Naval Oceanographic Office, in collaboration with other 
interested Offices of the Navy Department, is considering the de- 
velopment of an oceanographic system consisting of a transportable 
oceanographic laboratory, manned by one person, capable of obtain- 
ing oceanographic and meteorological measurements in ships-of- 
opportunity at speeds up to 23 knots. The laboratory van would 
contain essential instruments and equipment, including expendable 
sensors, to accomplish this mission. It would be self-sustaining with 
respect to electrical power and essential services. It would be of 
light, rugged construction, fully weatherproof, transportable to and 
from port areas by truck, rail, or air and designed for simplified 
loading and offloading from ships of various sizes and configurations. 

An engineer or graduate student would operate the laboratory, 
including attached appurtenances (boom, winch), recorders, and ex- 
pendable sensors. The data would be obtained with modern electronic 
instrumentation and recorded in analog or digital format, as appro- 
priate, with provision for the entry of complementary navigational 
data. The format in which the data would be collected must be com- 
patible with data processing, storage, and retrieval methods employed 
by the National Oceanographic Data Center and the Naval Oceano- 
graphic Office, which would be the recipients of the data collected. 

The essential components of the ships-of-opportunity oceano- 
graphic system would be as follows: 

(a) An expendable sensor capable of measuring temperatures 
and sound velocity to a depth of 2,000 feet. This instrument might 
consist of two parts, namely, a buoy at the surface to telemeter data 
to the laboratory van and a free-fall element containing the sensors. 


SCIENCE AND THE SEA 


(b) Anunderway water sampler with the capability of collecting 
water samples from preselected depths to 2,000 feet, the quantity of 
which will be sufficient for quantitative and qualitative analyses of 
alkalinity, disolved gases, nutrients, and trace elements, namely, 
oxygen, nitrogen, reactive phosphate, total phosphate, reactive 
silicate, nitrate, and magnesium sulphate, within state-of-the-art 
precision. 

(c) A high-speed plankton sampler with the capability of col- 
lecting plankton samples at preselected depths to 2,000 feet, and 
indicate the total volume of water sampled. 

(d) A towed echo sounder with an accurate depth recorder of 
high resolution. 

(e) Other sensors to record wind direction, wind speed, baro- 
metric pressure, air temperature, and solar radiation. 


The immense unit cost of the transportable oceanographic 
system may, due to the ever present budgetary consideration, limit 
the number of units available for the synoptic network. The fol- 
lowing is a rough estimate of what the van concept may cost: 


Van $10,000 

Equipment $150,000 

Personnel $10,000 (year) 

Ship Services $8,000 (10 crossings, year) 


Such a high cost of establishing a single data base may tend to 
defeat the original purpose of the ships-of-opportunity program, for 
low operating costs is cited as being one of its more attractive 
features. If it hinders a maximum expansion of the synoptic net- 
work, so necessary to military and commercial operations, it will have 
fallen short of its main objective. 


48 


Accordingly, project officials are not abandoning the concept of 
using inexpensive, foolproof instruments aboard ships-of-opportunity, 
utilizing ship’s personnel to obtain and transmit the data. For the 
very near future, available instrumentation will restrict observations 
primarily to temperature versus depth observations. As simple 
equipment to acquire data concerning other parameters is developed, 
the program could be modified to include it. 


CONCLUSION 


‘The forementioned projects, all experiments in the physical 
utilization of ships-of-opportunity, have proven that an undeterminate 
potential for marine data acquisition exists in that mode. Participants 
in each of the projects undertaken to date are generally agreed that 
we have only begun to explore that potential. Certainly, a number 
of problems have yet to be solved before total utilization becomes a 
reality. Most of the problems are apparently technical ones which 
undoubtedly will be resolved as the need arises. The important thing 
is that project officials are convinced that a useful system will 
evolve. If it does, the ships-of-opportunity concept will bring to- 
gether, in a unique fashion, military, academic, and commercial 
organizations seeking a common objective—the advancement of our 
Nation's welfare through the improvement of our knowledge of the 
oceans. 


OCEAN STATION 
VESSELS 


By John W. Chanslor 
Maritime Safety Division 
U.S. Naval Oceanographic Office 


To the mariner and aviator alike, the manned ocean station is 
virtually an information bureau, ready at all times to report the 
latest weather information, furnish navigational data, relay messages, 
and furnish search and rescue service in case of emergency. 

An ocean station is an arbitrarily selected section of ocean 210 
miles square, strategically located hundreds of miles from the nearest 
land. Ocean station vessels are, strictly speaking, ‘‘on station” when 
they are within this square. 

The actual establishment of ocean station vessels had its begin- 
ning with World War II. With the cessation of weather reports 
from merchant ships, weather data became of paramount importance 
in the safety of transocean flights. For this reason ocean station 
vessels were first established in the Atlantic in 1940 and later in the 
Pacific in 1943. Additional stations were added as needed, with the 
numbers of ocean station vessels fluctuating greatly during the war 
and postwar years. There are at present 9 ocean station vessels in 
the Atlantic and 3 in the Pacific, Figure 2. 


49 


The radiosonde, containing a radiometeograph which transmits 
data on upper atmospheric pressures, humidities, tempera- 
tures, and wind velocities. 


hea 
¥| 
Ba 


Ocean station vessels, frequently referred to as “weather ships”, 
have been under the cognizance of the International Civil Aviation 
Organization (I.C.A.O.) since 1947. United States participation in 
this international weather program falls within the jurisdiction of 
the U.S. Coast Guard. The following article is intended to describe 
some of the various functions of these vessels. 


METEOROLOGICAL SERVICE 


Despite progress in ship design, weather at sea is still the 
greatest single cause of marine casualties and delays. Head winds 
increase the length of a sea voyage and are of vital concern to an 


SCIENCE AND THE SEA 


aircraft on a transocean flight. Accurate information on the veloc- 
ity and direction of winds at several levels along established routes 
is essential to proper loading and fueling prior to an overseas flight. 

The daily weather observational program of each ocean station 
vessel consists of: 

(1) All foreign ocean station vessels and two of the six United 
States ocean station vessels, BRAVO and NOVEMBER, make and 
report hourly surface observations. The remaining ocean station 
vessels report surface observations every 3 hours. These surface 
observations include wind, weather, visibility, pressure, air tempera- 
ture and humidity, sea temperature, direction, period and height of 
waves, and details regarding cloud formation. 

(2) Upper wind observations, by radar, to an average height 
of about 54,600 feet, every 6 hours. 

(3) Radiosonde observations (pressure, temperature and 
humidity), to an average height of about 80,400 feet, every 12 hours. 
These upper air observations involve launching of a gas-filled balloon 

“equipped with a radar reflector and/or a miniature radio transmitter. 

Reports from United States North Atlantic Ocean Station Vessels 
are forwarded by radio to the U.S. Weather Bureau collection center 
at Washington, D.C., and those from the North Pacific waters ure 
sent to the Coast Guard radio station in San Francisco, California. 
Distribution of the data is made to domestic meteorological offices 
over teletypewriter circuits and to foreign services by radiotelegraph 
and radioteletypewriter broadcasts. Observations originated by 
weather ships maintained by other countries are relayed to the U.S. 
Weather Bureau along with other weather data in international radio 
exchanges. All weather observations are prepared for transmission 
in international weather codes. 

Reports furnished by weather ships, along with other reports 
received from merchant vessels and continental and island stations, 
complete the synoptic and upper air meteorological coverage over 
the Northern Hemisphere. These data are first plotted on charts for 
the surface and for several levels in the upper atmosphere. Upper 
air charts show temperature, wind distribution and moisture values 
for the 850 millibar (averaging 4,800 feet above sea level), 700 mb. 
(about 10,000 feet), 500 mb. (about 18,000 feet), 300 mb. (about 30,000 
feet), 200 mb. (about 40,000 feet) and 100 mb. (about 54,000 feet), 
constant pressure surfaces. From these charts, the meteorologist 
prepares weather forecasts and advisories for scheduled ocean flights. 
Frequently, because of the distance between ocean stations, he must 
forecast conditions over a large area of the route on the basis of 
successive upper air reports from a single ocean station vessel. 
Hence, the accuracy of data is of paramount. importance. 

Flight plans are made on the basis of conditions shown on the 
weather charts. Aircraft, of course, are primarily interested in 
making accurate determinations of fuel requirements and maximum 
payloads that can be carried with safety. The route and flying 
altitude is selected by the pilots to take maximum advantage of 
favorable weather and winds so the flight can be completed in the 
shortest possible time. Ocean flights sometimes follow one of the 
contour lines shown on a constant pressure chart for as much of the 
route as possible in order to take advantage of the favorable winds. 
This technique is familiarly known as “pressure pattern flying.” 


There have been many occasions when upper air reports from 
weather ships provided the only data on which the meteorologist was 
able to forecast the development of storms over the oceans. Apart 
from the large number of lives saved by the ocean station vessels 
and the reliable forecasts made possible by their observations, the 
mere presence of these stations takes a considerable strain off the 
minds of pilots. 

In addition, an aircraft can obtain reports of observations from 
an ocean station vessel in plain language or “Q” code, or in the ap- 
propriate international meteorological code, according to the method 
requested by the aircraft. As English speaking operators are 
carried on commercial transocean flights, “Q” codes are seldom used, 
and an intended change in ICAO procedures will abolish "Q” codes 
for ship to aircraft transmissions. 


OCEANOGRAPHIC DATA COLLECTION 


United States ocean station vessels have traditionally collected 
the maximum amount of oceanographic data possible. These include 
bathythermograph observations, plankton tows, and echo soundings. 


Lack of adequate instrumentation, however, has precluded any full- 
scale observations. 

Prior to 1961, oceanographic work by the Coast Guard was 
limited to the support of the International Ice Patrol, and what 
could be accomplished on a cost free and not-to-interfere basis. 
However, Public Law 397-87 was intended to bring the facilities and 
capabilities of the Coast Guard into the National Oceanographic 
effort. Along with this legislation, the Coast Guard, representing 
the Treasury Department, became a member of the Interagency 
Committee on Oceanography. 

To implement oceanographic observations from ocean station 
vessels, one ship was outfitted in 1962 as a prototype and, to date, 
has conducted a complete oceanographic program on two ocean 
station cruises. These observations were made under the super- 
vision of a team of U.S. Naval Oceanographic Office and Coast 
Guard oceanographers. 

Based on the experience gained with the prototype ship, a con- 
tinuing program is now underway for outfitting all major cutters 
assigned to ocean station duties, so that a basic oceanographic 
capability will be provided in all ships. In cooperation with the 
U.S. Naval Oceanographic Office, and in addition to other oceano- 
graphic instrumentation, these ships are being equipped with wave 
recorders and electronic bathythermographs. Installation has com- 
menced and will proceed at the rate of about one ship per month 
over the next two and one-half years. 


POSITION—INDICATING GRID SYSTEM 
OCEAN STATION VESSELS 


LH 
\ ay! HH 
\\ i il ny 


{] 

0 
Es iizo) 2 
T 


! 


NU od IT 


+ 


A A 
a [B 
C 
D 
E 
F | 
G| 


H 
l 
J 
O 
K 
L 
M 
NI 


READ LATITUDE DESIGNATOR FIRST 


| 


<|€|5)|0}-0|2/=|-|z/OlE|—|zla|>|m[5]a 


me 
AN 
fL 


<|C|H|v/O|-0 


U|V 


are 10 naulice! miles apart 


Figure 1. Position indicating grid. 


NAVIGATIONAL AIDS 


Originally, an ocean “station” included the area within a 100- 
mile radius of an assigned control point. World War II proved this 
impractical, and, consequently, this limit was discarded. After the 
war, to assist weather ships in carrying out their mission as aids to 
surface and air navigation, the “station” was changed to a grid 210 
miles square, Figure 1. This grid is divided into 10-mile squares. 
The purpose of the grid is to provide a device for the ocean station 
vessel to indicate its position on her medium frequency radiobeacon. 
The signal transmitted by the radiobeacon is a continuous carrier 
wave with identifying letters superimposed on it. This signal con- 
sists of four letters; the first 2 letters comprise the characteristic 
signal of the station and the last 2 indicate its position within the 
grid. If a ship is on station, i.e., within the 10-mile square at the 
center, the last two letters of the signal are “OS”, the latitude and 
longitude designators, respectively. If the ship is outside the center 


OCEAN STATION VESSELS 


SRR 


a ia 


nate 


Maintaining position, during winter in the North Atlantic at 


ocean station BRAVO. 


2 


10-mile square but still on the grid, the latitude and longitude 
designators of whatever square the ship is in are transmitted as the 
last 2 letters of the signal. The latitude designator is always given 
first. The center of each grid square should be considered the 
location of the station vessel for all computations, thus giving a 
maximum error of 7.1 miles and an average probable error of 2.5 
miles. 

EXAMPLE: Assuming we are considering station “ALFA” with 
the actual position of the station vessel at the point marked “X” on 
the grid in Figure 1, her signal would be “YAIN”. It is also evident 
that the station vessel bears 63° true 45 miles from its assigned 
position. 

The emission of the radiobeacon has a high degree of vertical 
polarization which may enable a surface vessel to obtain a good 
bearing at distances in excess of 200 miles. If the regular beacon 
equipment breaks down, the same service as described above will be 
given, except that the ship’s communication transmitter will give 
an interrupted tone-modulated signal in place of the continuous 
carrier wave. In this case, the identifying signal will be followed 
by a 20-second dash in order to provide service for automatic direc- 
tion finders. If a station vessel is off the grid completely, as when 
on a distress mission, no beacon service will be furnished, except 
when specifically requested for homing purposes. In this event, the 
international radio call of the station will be used as the identifying 
signal. 


CAUTION TO ALL SHIPMASTERS — AVOIDANCE OF 
COLLISION WITH OCEAN STATION VESSELS—Instances have 
been reported of ships “homing” on beacon transmissions of these 
vessels on station. This practice creates a grave danger of collision. 
Vessels occupying ocean stations may be drifting with engines on 


Official U. S. Coast Guard Photographs 


51 


standby. Standby, in this instance, means that the vessel is not able 
to maneuver as propulsion power is not immediately available to the 
bridge. While ocean station vessels are drifting on station they 
use the lights and shapes prescribed by Rule 4(a), International 
Rules, and the fog signals prescribed by Rule 15(c)(v), International 


Assigned position peadloheacony 
I- 
Inter-|den- | Fre- 
Station Nationality na- | ti- ency 
Latitude | Longitude | tion-| fi- ke Ss.) 
al ca- 
call | tion 
ALFA ===-==- British; Netherlands; | 62°00'N.| 33°00'W.| 4YA| *YA| 347 
French; Norwegian; 
Swedish. 
BRAVO ---- | United States- ---- 56°30'N. 51°00'W.| 4YB| *YB| 391 
CHARLIE - - - | United States-- --- 52°45'N 35°30'W.| 4yC| ?¥C| 385 
DELTA- ---- United States- - - 44°00'N 41°00'W.| 4YD| *yD} 350 
IEXCHO- - ---- United States-- - - - 35°00'N 48°00'W.| 4Ym WE 362 
INDIA- ----- LEDS SEISNTEEG 59°00'N. 19°00’W.| 4YI YI | 388 
rench. 
JULIETT - - - EEG Netherlands; | 52°30'N. 20°00'W.| 4yJ | *yJ | 370 
ench. 
IMHO CSOSSS ELEVEN NCIS UE 45°00'N. 16°00'W.| 4YK| ‘YK | 357.5 
rench, 
MIKE ------ Norwegian-Swedish; 66°00'N. 2°00'E. | 4¥M| SYM | 340 
Netherlands. A 
NOVEMBER- - |United States- - - - - 30°00'N. | 140°00'W. | 4YN| (YM | 335 
PAPA== =< Canada--------- 50°00’N. | 145°00'W. | 4YP EYP 388 
VICTOR ---- |United States- ---- 34°00'N. | 164°00'E. | 4YV| “YV | 391 


‘The collective sign for any or all United States ocean station vessels in the At- 
lantjc is NMMZ. 

The collective call sign for any or all United States ocean station vessels in 
the Pacific is NDLZ. 

*Operates for 5-minute periods beginning at 5, 20, 35, and 50 minutes past each 
hour, and on request. 

‘Operates for 5-minute periods beginning at 5, 20, 35, and 50 minutes past each 
hour but may be interrupted 1100—1200 and 2300—2400 GMT due to radiosonde obser- 
vations. 

‘On request. 


Figure 2 Pertinent data regarding ocean station vessels. 


SCIENCE AND THE SEA 


Rules. Therefore, all precautions to avoid collision must be observed. 
The beacon transmission may be used by surface ships to determine 
positions and should be used to avoid collision with the transmitting 
vessel. 

The assigned geographical position of each ocean station vessel 
is indicated on the appropriate Pilot Chart. Additional information 
regarding radio aids is shown in Figure 2. 

As it is rare for modern aircraft to be fitted for transmission on 
“medium frequency”, the ocean station vessel’s medium frequency 
direction finder is now used only for her own navigational purposes 
and getting bearings on surface vessels or other survival craft in 
emergency. 

The air search radar in ocean station vessels is primarily used 
for tracking the radar target used on balloons, when measuring 
upper winds. This radar is also used when providing navigational 
fixes to aircraft. Currently, all U.S. and many European ocean 
station vessels are being equipped with balloon tracking radar in 
addition to their air search radar. 

When in contact with ocean station vessels, nearly all aircraft 
request a radar fix in addition to the latest information regarding 
upper winds and surface weather. The frequency with which these 
requests are made varies from station to station. However, a good 
example is station “J”, with an average of 78 weather and naviga- 
tional requests each day from aircraft. A summary of the services 
provided by station “J” during 1962 follows: 


Wieathermeportsitolalrcralu yi ene rreeeee iret 5,223 
Radardixeseeererrrer cer Baa Ag eR A CO arn ony i 13,874 
Radiobeacons by special request......................... 9,424 
WHALES caooenbeedtoo sidoos bone ites Oc Dada etad Hiirin Aeaeenan ora eh 28,521 


SEARCH AND RESCUE 


In addition to supplying meteorological information and acting 
as limited navigational aids, ocean station vessels are required by 
ICAO agreement to participate in search-and-rescue, and to main- 
tain a high degree of readiness. These ships guard 500 kes. 
continuously for distress, urgency, and safety communications. 
Also, United States ocean station vessels continuously guard the 
international distress voice frequency 2182 kes., the international 
aeronautical emergency frequency 121.5 mes. (voice), air-search 
VHF working frequency 126.7 mes. (voice), air-surface UHF working 
frequency 272.7 mes. (voice), and the U.S. Military common 
emergency frequency 243 mes. (voice). The international survival 
craft frequency 8364 kes. is guarded only during the distress or alert 
phase of SAR incidents. 

The frequency of 500 kes. is the one that should normally be used 
by merchant ships when calling the ocean station vessels. After 
contact has been made on 500 kes., a working frequency will be 
established. Ocean station vessels, BRAVO and CHARLIE in the 
Atlantic and VICTOR in the Pacific have medical officers aboard 
and are prepared to give medical assistance. 

Search and rescue is under the cognizance of the U.S. Coast 
Guard and is greatly supplemented by the AMVER (Atlantic Mer- 
chant Vessel Report) system. This maritime mutual assistance 
program is explained in H. O. Pub. No. 117A, Radio Navigational 
Aids—Atlantic and Mediterranean Area. Search and rescue of air- 
craft in the Pacific Ocean is affected by SAR Plan ALFA. This plan, 
plus additional SAR information, is explained in H. O. Pub. No. 117B, 
Radio Navigational Aids— Pacific and Indian Oceans Area. 

A governing rule for search and rescue states: “If an ocean 
station vessel is able to lend assistance to an aircraft or vessel in 
distress, or survivors from same, it shall immediately grant priority 
of service to search and rescue.” 

Frequently, the Commanding Officer of an ocean station vessel 
is called upon by a rescue coordination center to control search and 
rescue at the scene of the incident. During such events he ensures 
complete coverage of the area by assigning search areas to all avail- 
able ships and craft. In addition, he maintains a communication 
center, keeps a search plot, and prevents a hazardous concentration 
of searching units. 

The final decision to leave an ocean station for a search and 
rescue mission rests with the Commanding Officer of the ocean 
station vessel. This decision is weighed on the probability of rescue 
against the hazards to air traffic created by the ships absence. The 


52 


ICAO Ocean Station Vessel Manual states that the vessel shall go 
on a search and rescue mission only when, in the opinion of the 
Commanding Officer, there is a reasonable chance of succeeding. 

A recent example of the effort an ocean station vessel will make 
on a search and rescue mission was the successful recovery by the 
U.S. Coast Guard Cutter Absecon of a German seaman after he had 
spent 17 hours swimming in the Atlantic. This ordeal, as reported 
by the U.S. Coast Guard, began on the evening of 12 September 1963 
when Franz Strycharezyk, third engineer of the German cargo ship 
Freiberg, was leaning over the guardrail for a breath of air, prior 
to retiring. Unexpectedly, the Freiberg took a heavy roll and threw 
him into the sea. 

The spot where Franz fell overboard was in the middle of the 
Atlantic, approximately halfway between Bermuda and the Azores. 
A lonelier place could scarcely be imagined. On all sides of Franz 
stretched an immensity of heaving water. In that vast watery 
expanse, it didn’t seem possible for anything so insignificant as a 
human being to survive. Fortunately for Franz the water was a 
warm 80 degrees, and the air was mild. 

Nevertheless, the odds against his being spotted were astro- 
nomical. Mathematically, they could be calculated at the figure one 
followed by nine zeroes. It is just as well that he wasn’t a mathe- 
matician, because it wouldn’t have done his morale much good. 

Racing through Franz’s mind was the disturbing thought that 
it would be several hours before his absence would be discovered, as 
he wasn’t due to relieve the watch until midnight. And, even if a 
search were undertaken by the Freiberg, what chance was there that 
they could find him? 

Stubbornly, he held on, hoping for a miracle. And sure enough, 
a few hours later, the Freiberg, having discovered Franz’s absence 
returned to the approximate spot where he had fallen overboard. 
After a search of several hours, she had broadcast a ‘man overboard” 
message to all ships in the area. That was at 0122. Ironically, the 
Freiberg had come so close to Franz that she nearly passed over him. 
Once again he was left to the loneliness and darkness of the mid- 
Atlantic. It was heartbreaking, after being so close to rescue. He 


fell back on his last resouree—prayer. His worst enemies now, in 
addition to the black water, were fear and despair. His situation 
wasn’t made any easier by an 8-foot sea, a heavy sky, and constant 
drizzle. 

The big thing now was not to panic. To conserve his strength, 
Franz swam as little as possible, floating most of the time. 

About 130 miles from the area where Franz was putting up his 
heroic fight for survival, the Coast Guard cutter Absecon was 
patrolling on Ocean Station ECHO. It was after midnight and, 
except for the duty watch, her crew, including the skipper, had turned 
in. The Absecon was now in the 19th day of her patrol and was 
due to be relieved in two days to return to her home port of Norfolk, 
Va. The radioman was at his post, but so far it had been a routine 
mission. Then, at 0122, the Freiberg’s anxious message came through. 
Excitedly the radioman gave the news to the supervisor of the 
watch,who followed routine procedure and immediately relayed the 
message to the Coast Guard’s Eastern Area Command. There it 
was fed into the Coast Guard’s Atlantic Merchant Vessel Reporting 
(AMVER) office in New York City. At this nerve center of rescue 
operations, the Coast Guard maintains contact with merchant vessels 
in the Atlantic. By using an electronic computer, it is able to de- 
termine within seconds which vessels are closest to the emergency 
and to forward this information to the distressed ship. 

After sending off the message to New York, the supervisor of 
the watch on the Absecon went forward to awaken the Commanding 
Officer and give him the news. The Freiberg’s call had put into 
motion the Coast Guard’s entire search and rescue complex along the 
Atlantic coast. Once again an ocean station vessel was demon- 
strating its readiness to mobilize all its resources to save a single 
human life. 

Even before he had finished dressing, the Commanding Officer 
phoned the bridge and ordered full speed ahead to the area of search. 
He estimated there was an outside chance that Franz was still alive. 

By 0140 the Absecon was under way. Enroute, the Commanding 
Officer held a council with his executive officer and navigator. 
They decided upon a “Papa Sierra” or Parallel Track Single Unit 
search pattern as offering the best chance of success. 


OCEAN STATION VESSELS 


A typical U.S. Coast Guard ocean station vessel. 


At 0759 the Absecon reached the search area. But, its opera- 
tions were hindered by heavy skies and steady rain. Things didn’t 
look too promising until a little after one o’clock, when the weather 
cleared a bit. That gave the Captain the opportunity to take a 
“murky haze” fix with a sextant. After calculating drift and other 
factors, he decided that the most promising possibility lay about 
eight miles to the north. Accordingly, he changed the search sector. 

Every man that could possibly be spared was now on the deck of 
the Absecon searching the horizon. One of the ship’s officers, 
standing on the bridge, saw what appeared to be a speck moving in 
the water. As the ship changed course and came closer, he could 
make out a man vigorously shaking an article of clothing. Incredibly, 
it was the German seaman. He was waving his undershorts to attract 
attention. That was about 1402. Two minutes later, the Absecon 
came alongside Franz, lowering its cargo net for him. 

Despite his exhausting 17 hours in the water, Franz climbed the 
net and reached the deck where willing hands pulled him on board. 
It was then that he collapsed. But, he had won an incredible battle 
with the sea. His stamina and indomitable will to survive had pulled 
him through. That, plus the good professional judgment and skill of 
the Commanding Officer of Absecon had brought about a sea rescue 
that would be long remembered. 

After a couple of hours of rest, Franz was examined by a Chief 
Medical Corpsman, who was amazed at his excellent physical condi- 
tion. The expertise of the Coast Guard had paid off well indeed. 

After Franz regained his strength, the Absecon arranged a 
rendezvous with his ship, the Freiberg, and on September 14 he was 
restored to his shipmates. 


53 


So if you think Friday the thirteenth is unlucky, don’t mention 
it to Franz Strycharezyk. As far as he’s concerned, it'll always be 
the biggest day on his calendar. 

Since 1953 no less than 253 lives have been saved by ocean 
station vessels. Most of these rescues were related to marine acci- 
dents. It has been more than 7 years since a large number of air 
travelers have been rescued by an ocean station vessel. On 16 
October 1956 the U.S. Coast Guard Cutter Ponchartrain, while 
serving on ocean station NOVEMBER, vectored and controlled the 
ditching of a distressed transpacific airliner. All of the 31 pas- 
sengers and crew were saved. Since then, only military aircraft 
have ditched and required assistance. 

Apart from providing necessary navigational information to 
pilots who have decided to ditch their aircraft, the ICAO Manual 
recommends several means of assisting pilots. During periods of 
reduced visibility, the ocean station vessel may lay out a flare path 
of lighted floats along the ditching track indicated by the pilot. 
And, in addition, a searchlight beam may be trained horizontally in 
the ditching direction. During the hours of daylight, smoke floats 
may be utilized to indicate wind direction to the aircraft. Of course, 
radio and radar bearings will guide the aircraft to the chosen path of 
ditching. By turning circles with a diameter of more than one mile 
or by laying an oil slick, it is possible for vessels, under certain con- 
ditions, to smooth the seas. 


OPERATIONS 


United States ocean station vessels are cutters especially equip- 
ped for taking meteorological and oceanographic observations. In 


SCIENCE AND THE SEA 


addition to the regular crew, four highly trained U.S. Weather 
Bureau technicians are assigned to each vessel to conduct the 
meteorological program. 

These ships remain at sea from 25 days to 6 weeks. United 
States ships spend 21 days “on station” steaming within the 10-mile 
square center of the station grid. The depth at each station is well 
over 1,000 fathoms. However, the U.S. Coast Guard has marker 
buoys moored at ocean stations CHARLIE, NOVEMBER and PAPA, 
and in the near future plans to have all U.S. stations so marked. 

For all practical purposes, the Commanding Officer of a station 
vessel does not need to know his exact position. However, it is 
obvious that the greater navigational accuracy he can achieve, the 
greater will be the accuracy of fixes to aircraft, meteorological data 
obtained, as well as being in a better position to commence a search 
and rescue mission. Under average conditions the accuracy of a 
radar fix given to aircraft at a slant range of 50 miles is about 
7 miles. Ataslant range of 100 miles the accuracy is about 10 miles. 

The United States nominally operates 18 vessels in this program, 
3 for each of the assigned stations. However, the U.S. Coast 
Guard actually employs a total of 32 vessels in the program. This 
additional number is to maintain a uniform schedule throughout the 
Coast Guard Fleet. Thus, these ships are available for other duties 
as well as ocean station patrols. 

When the wind exceeds force 10, Commanding Officers of ocean 
station vessels have found that they are usually required to steam 
at slow speed. However, the decision to run with the wind, or 
place it on one bow, depends on circumstances. Usually it is 
preferable to place the wind on one bow, so that it will not interfere 
with the upper air balloon launching schedule. During the 23 years 
that weather ships have been in operation, there have been few 
occasions when very prolonged storm conditions forced a ship outside 
the limits of the station grid. 


ATLANTIC—HISTORY 


The prelude of an international weather service began with The 
International Conference on Safety of Life at Sea, “Convention 
and@ Final Act”, which was signed in London, 31 May 1929. During 
this conference it was agreed that ships encountering tropical 
storms would make weather observations and further transmit their 
findings. Such reports were to include: (a) position and movement 
of the storms, (b) barometric pressure, (c) barometric change during 
the previous two to four hours prior to the storm, (d) wind direction, 
(e) wind force, (f) state of sea, and (g) sea swell. Amplifying 
reports were to be transmitted every three hours thereafter, as long 
as the ship remained under the influence of the storm. In addition, 
certain selected ships were to take meteorological observations at 
specified hours for the benefit of other ships and various official 
meteorological services. 

At the onset of World War II in, 1939 surface weather reports 
which had normally been transmitted by transatlantic shipping were 
discontinued. For their own protection, belligerent nations required 
their ships to maintain radio silence. The passage of the Neutrality 
Act then halted U.S. shipping in the European trade. This resulted 
in the almost complete absence of weather reports from the North 


Atlantic Ocean area. Further complicating the situation was the 
increase in transoceanic flying activity, which required complete 
and accurate weather information. Thus, there was a self-evident 
need for an Atlantic weather observational service from ships 
strategically placed to best provide the required meteorological data. 

In January 1940 the President withdrew the U.S. Coast Guard 
cutters performing neutrality patrol off the Grand Banks and 
directed the Coast Guard to establish ocean weather stations with 
the vessels. Two stations were established 10 February 1940 namely, 
Atlantic “1” and “2” at 35.6°North, 53.3° West and 37.7° North, 
41.2° West, respectively between Bermuda and the Azores. These 
stations were occupied by cutters with the Weather Bureau 
providing the meteorological personnel and equipment. 

In 1940 Great Britain was suffering great shipping losses and a 
decision was made to fly American-built bombers directly from 
Newfoundland to Britain. This resulted in the establishment of a 
third ocean station about 500 miles northeast of Newfoundland. By 
July 1942 the first fighter planes were being flown across the 
Atlantic via a chain of U.S. Army airfields bridging theocean from 
Labrador to Greenland to Iceland. As a result of this new opera- 
tion, two more plane guard stations were established; one at 
58° North, 52° West, between Labrador and Greenland, and the other 
at 63°North, 31.5°West, between Greenland and Iceland. These 
plane guard stations were primarily established for air-sea rescue 
and navigational assistance rather than to obtain meteorological 
data. As the stations were not a part of the ocean weather program, 
few meteorological records were obtained. 

The number and locations of ocean weather stations manned by 
U.S. ships were originally determined by the U.S. Weather Bureau 
in consultation with commercial airlines. With the advent of the 
war, stations were determined by the cognizant committees under 
the Joint Chiefs of Staff, primarily the Meteorological Committee, 
of which the Weather Bureau was a member. Later, with the 
establishment of the Air Coordinating Committee, that body recom- 
mended and approved the number and location of stations. The 
locations of previously mentioned Atlantic “1” and “2” were changed 
several times during the war as the increase of air transportation 
dictated different flight routes. Even these positions could not be 
maintained consistently, due to enemy submarines and rescue duty. 
Consequently, these two stations were moving much of the time. 

The operational control of the entire weather patrol in the 
Atlantic Ocean was assumed by the Navy for reasons of military 
security and exercise of command in March 1944. The United States 
stations in the North Atlantic were then operated by Task Force 24 
and station numbers as well as locations varied in accordance with 
requirements. 

After VE Day in May 1945 the biggest movement of aircraft in 
history began across the North and South Atlantic to the Pacific 
theater. To safeguard the tremendous increase in air traffic, plans 
were laid for increasing the number of weather stations in the 
Atlantic resulting in a total of 21 by June 1945. Of these 21 stations, 
6 were maintained by the United Kingdom, 2 by Brazil, 2 jointly by 
Brazil and the United States, and the remaining 11 by the United 
States. 


OCEAN STATION VESSELS 


At a conference with the Chief of Naval Operations on 1 March 
1946 it was agreed, because of personnel limitations, to reduce the 
Atlantic stations to 6 by 15 March and on that date to return opera- 
tional control back to the Coast Guard. The British were suffering 
from similar personnel limitations and progressively withdrew their 
vessels, until on 1 May 1946 the United States was the only govern- 
ment maintaining any ocean station vessels. 

The need for the services supplied by the patrol vessels had not 
decreased since the war, because, as military flying decreased, com- 
mercial flying operations increased. The first steps to establish the 
weather patrol on a permanent peacetime basis were taken at the 
North Atlantic Route Conference of the Provisional International 
Civil Aviation Organization (PICAO) in March 1946 at Dublin, 
Ireland. To maintain a North Atlantic weather service that would 
also provide adequate air navigation facilities, the conference 
recommended that a minimum of 18 stations be established. These 
stations were to be maintained continuously by vessels thoroughly 
equipped with modern meteorological instruments, electronic navi- 
gational gear, and trained technical personnel. The United States, 
operating approximately sixty-five percent of the transatlantic 
aircraft, was to provide seven stations, plus an eighth station in 
cooperation with Canada. 

The Council of PICAO (now ICAO) approved these reeommenda- 
tions in the latter part of May 1946. To further implement this 
action, the United States of America was requested to meet with 
Belgium, Canada, Denmark, France, Iceland, Ireland, The Nether- 
lands, Norway, Portugal, Spain, Sweden, and the United Kingdom 
to investigate the situation thoroughly. This conference was held 
in London, England, in September 1946 and resulted in a signed 
International Agreement that 13 permanent Atlantic ocean weather 


stations were to be established not later than 1 July 1947. All terms 
of the agreement were to come into force 25 August 1947 and remain 
until 30 June 1950. Further, a conference was to convene not later 
than 1 April 1949 to consider revision and renewal of this agreement. 

On 1 July 1946 the Coast Guard was assigned directional control 
of the entire program for stations maintained by the United States. 

Since 1954 there have been 9 ocean station vessels in the North 
Atlantic and these will apparently remain for many years. 


PACIFIC—HISTORY 


The history of the Pacific ocean station vessels began in 1943 
when the Commander in Chief of the U.S. Fleet ordered the 
establishment of two weather reporting stations in the Pacific. One 
was established between the Hawaiian Islands and the California 
coast, the other in the Gulf of Alaska. 

During the war all stations were manned by the U.S. Navy. 
Since the war, however the stations have been manned by the U.S. 
Navy or by the U.S. Coast Guard with U.S. Weather Bureau 
observational personnel. 

The Pacific network was progressively expanded until 1 
January 1946 when a total of 24 weather and plane guard stations 
were in operation. Except for one Canadian-manned station, the 
U.S. Navy exercised full directional and operational control over 
the Pacific station vessels. 

Late in February 1946 the Pacific network began to feel the 
impact of the same obstacles which were forcing a reduction in the 
Atlantic operation and several stations were discontinued. 

On 15 April 1946 the U.S. Coast Guard took over operational 
control and on 1 July 1946 assumed directional control. 

Currently a total of 3 ocean station vessels exist in the Pacific. 
Two of these stations are manned by the United States and one by 
Canada. 


Removing a 300-ton shroud of ice, to maintain stability. } 


SCIENCE AND THE SEA 


SUPPORT 


At the present, a total of 22 nations share in the cost of 
operating Atlantic Ocean Station Vessels. The contribution of each 
nation is based upon the number of Atlantic crossings by civil air- 
craft belonging to it, plus a share of the “non-aeronautical benefit” 
factor. In addition to the support furnished by the operating 
nations, eleven nations assist with cash contributions. 

During the years that ocean station vessels have been in 
existence, their regular meteorological observations have proved 
very valuable not only for aviation but also for general meteoro- 
logical purposes. Member nations have held conferences regularly, 
the latest one being the Fifth North Atlantic Ocean Station Con- 
ference held at The Hague, Netherlands, in March 1960. At the 
suggestion of the Government of the Netherlands during this 
meeting, adjustments were made in the scale of cash contributions 


to take into consideration the prevalent tendency for cost increase. 

It is difficult to assess the actual cost of operating all of the 
ocean station vessels, as some are also used for other purposes. 
However, the 1961 figures show that for ships used entirely for this 
purpose, the annual cost varies from $270,000 for Norwegian ships 
to $943,000 for U.S. ships. For each of nearly one and a half million 
passengers who flew across the Atlantic, this means that only a few 
dollars were spent on the essential services of ocean station vessels. 
Or stated in a different way, the cost of operation of all weather 
ships cost just slightly more than the purchase price of one jetliner, 
with required spares. 

The number of years ocean station vessels will be required to 
fulfill all of their current duties remains to be seen. Even with 
rapid progress in constant level balloons and satellites, the Inter- 
national Civil Aviation Organization will have a need for these ships 
for decades yet to come. 


E DISTRIGUTION UF 
SCOLURED WATCH 


By Marine Sciences Department 
U.S. Naval Oceanographic Office 


INTRODUCTION 


Discolored water is recognized as patches, streaks or very 
large areas of more or less opaque brown, yellow, red and other 
tints on the water, or under the surface. These areas fre- 
quently resemble shoals. The purpose of this article and 
accompanying chart is to demonstrate the geographical factors 
in the distribution of these areas. We hope that this will be a 
significant contribution to the mariners’ problem of the clari- 
fication and correction of erroneous notations of shoal water 
on charts. 

Since about 1880 the Hydrographic Office has been receiving 
discoloration records from many sources, chief among which 
is the Merchant Marine. Reports in American and foreign 
scientific publications and nautical journals have likewise 
been used. The HYDROGRAPHIC BULLETIN, Hydrographic 
Office PILOT CHARTS, and the MARINE OBSERVER of the 
British Meteorological Office, have been most helpful. This 
collection of observations forms the basis for the accompanying 
chart and probably comprises the most complete record of the 
distribution of discolored water. 


HISTORY 


The phenomenon of the discolored water has undoubtedly 
been observed by voyagers and inhabitants of coastal areas 
since before the beginning of the written record. One of the 
earliest reports is found in the Bible, (seventh chapter of 
Exodus, the twentieth and the twenty-first verses:) 

“‘And all of the waters that were in the river (The 

Nile) were turned to blood and the fish that was in the 

river died; and the river stank, and the Egyptians 

could not drink of the water of the river.”’ 
Such reports may be found, also in the Iliad and the works of 
Tacitus and in the logs of a number of navigators of the 16th 
century and on. 

A few early records may be found with detailed description 
of the discoloration and of the organisms which cause it. For 
example, in 1594, Sir Richard Hawkins, entering a cove in the 
Straits of Magellan, observed a bright red discoloration of the 
water. He stated, ‘“‘they sounded a cove some sixteen leagues 
from the mouth of the straits, which after we called Crabby 
Cove. It brooked its name well for two causes; the one for 
that all the water was full of a small kind of red crabbes; the 
other, for the crabbed mountains which overtopped it; a third, 
we might add, for the crabbed entertainment it gave us.’’ 
Again, specifically mentioning discolored water, Simon 
D’Cordex in 1598, reported ‘‘having passed the Rio de la 
Plata, the sea appeared as red as blood, the water was full 
of little red worms which when taken out jumped from the hand 
like fleas. Some were of the opinion that with seasons of the 
year the whales shook these worms from their bodies but of 
this they have no certainty.’’ The available records prior to 
1800 attribute the discoloration in the sea to various factors 
such as sea dust, submarine earthquakes, submarine sulphur 


57 


springs, spawn of fish, etc. In 1729, during the voyage of the 
ship St. George, Capt. William Dampier described an encounter 
with discolored water off the coast of Peru as follows: 

‘“*The 19th instance, our men all being at dinner and 

our ship about ten leagues off shore, going with a 

fine fresh gale of wind at East, we were suddenly 

surprised with the change of the colour of the water, 

which looked as red as blood to as great a distance 

as we could see, which might be about seven or 

eight leagues. At first we were mighty surprised; 

but recollecting ourselves, we sounded, but had no 

ground at one hundred and seventy fathoms. We then 

drew some water up in buckets, and poured some in a 

glass. It still continued to look very red, till about 

a quarter of an hour after it had been in the glass; 

when all of the red substance floated on the top, and 

the water underneath was a clear as usual. The red 

stuff which floated on top was of a slimy substance, 

with little knobs, and we all concluded it could be 

nothing but the spawn of fish.’’ 

During the 19th century with the increase in shipping and the 
publication of the results of scientific expeditions and private 
investigations, considerable interest was aroused in the distri- 
bution of and the explanation for discolored water. Sailing 
directions requested that areas of discolored water be carefully 
surveyed and sounded to eliminate the possibility of their being 
recorded on the charts as shoal areas, and statements were 
published in nautical journals to the effect that some of the 
areas then reported as shoals were thought to be discolored 
water, 

In recent years outbreaks of discolored water appearing off 
the Florida and California coasts have been watched and 
studied with increasing interest. Comparison of data from 
the many known affected localities provides clues for the 
study of these areas which may, in turn, contribute to the 
discovery of the direct cause or the possibility of prediction 
of the phenomenon. 


NOTE: In the Interest of this problem, the U. S. Navy Ilydro- 
graphic Office has issued a request-to mariners to take soundings 
in discolored water to insure correct diagnoses before reporting. 
It has also requested reports on observations of discolored water 
as a check on present shoal notations. 


CAUSES 


The causes of the normal color of the sea are physical. The 
characteristic indigo of the open ocean can be explained by the 
scattering of the light as it reflects from the water. Coastal 
waters are generally greener, often with shades of brown or 
yellow. These colors can be traced to the pigments in the 
tiny plants and animals that inhabit the coastal waters, to the 
color of the bottom sands and muds where the water is shallow, 
and to the erosion products washed from the land by rivers and 
rainfall. Different water masses, when they meet, as when bay 


SCIENCE AND THE SEA 


COMMON TYPES OF PLANKTON AFFECTING COLOR CHANGES IN SEA WATER 


CERATIUM 
POUCHETIA 


GYMNODINIUM 


PERIDINIUM 


NOCTILUCA 


water enters the ocean, can often be recognized by the differ- 
ences in their color. 

The discolorations discussed in this article however, are 
largely caused by living organisms. These plants and animals, 
floating at and near the surface of the water, depending almost 
entirely on water currents for their transportation, are known 
collectively as Plankton. The organisms range in size from 
microscopic bacteria to forms as large as jellyfish and carry 
colored granules, (most frequently red), in their bodies. These 
colored organisms are distributed throughout the world from the 


58 


polar waters to the tropics. Although they occur in almost all 
waters in large numbers, their color does not become noticeable 
until they exceed their normal abundance. Millions of organisms 
in a small volume of water are required for definite dis- 
coloration. 

When the necessary combination of factors is just right, the 
Plankton reproduces at a great rate and the tremendously 
increased population is called a ‘‘bloom’’. If these organisms 
contain pigments, the bloom is visible as discoloration. Some 
of these causative factors are increased food material, more 
favorable temperature or salinity, etc. 

The bloom, however, is usually short lived. This tremendous 
population beyins to compete with itself for food which is fast 
being consumed. Also the waste products which may have been 
caused by killing off enemy forms now begins to pollute the 
water to the point where it kills off the bloom itself. The 
original situation which made conditions right may now have 
changed, the temperature may have dropped or risen to an un- 
favorable point, oxygen may have become scarce, etc. A change 
in wind or tide may often be sufficient to dispel the bloom. 

As is the case in all living forms, the basic foods are 
nutrient chemicals, (nitrates, phosphates, dissolved organic 
matter etc.) and the energy from the sun. The plant Plankton 
makes use of these and the animal Planktonlives on the plants. 

Coastal waters provide these nutrients in greater abundance 
than do the open seas because decomposing matter which 
supplies these chemicals, settles to the bottom, but in the 
shallow coastal water, remains within reach of the Plankton 
near the surface. Also, the population of these waters is 
greater than that of the open sea, accounting for the large 
supplies of decomposing material. Organic material washed 
from the land is another important source of food for the life 
of the coastal waters. Where the shore is steep-to and the 
water deep, upwelling may occur, bringing bottom materials to 
the surface. Such regions are often rich in Plankton. 

Polar waters are also rich, but mainly during the spring 
season when the products of decomposition, accumulating 
during the long dark winter, are released by the turbulence of 
the warming water for the use of the Plankton which is coming 
out of a sort of hibernation under the influence of the sun. 

Thus while coastal waters are characterized by a variability 
of conditions frequently favorable for Plankton blooms, the open 
ocean is stable and rarely changing even from place to place. 
Plankton and food are generally scarce. Nevertheless, unusual 
effects of wind or weather or unusual current movements may 
occasionally lead to discoloration. 


DISTRIBUTION 


The phenomenon of discolored water is almost cosmopolitan 
in distribution, although individual species causing discolor- 
ation may have a relatively localized range. There are reports 
of it from the antarctic seas, the temperate seas, the tropical 
seas and the arctic. 

Although records included on the accompanying chart are 
mainly those submitted by the merchant marine, and are there- 
fore restricted to commercial ship lanes, other data obtained 
by scientific expeditions and coastwise vessels corroborate the 
theory that discolored water is primarily a coastal phenomenon. 

The areas best known for discoloration are areas of up- 
welling. Here, at seasons when the current regime is proper 
for the phenomenon, the cold deep waters are brought up to 
the surface, carrying with them nitrogen and phosphates from 
decomposition products. This suddenly abundant supply of 
nutrients is often a ‘‘trigger mechanism’’ for the Plankton 
bloom. Upwelling is common off the coasts of Peru and Chile, 
the coast of Latin America, Mexico and California, the Florida 
Keys, the Malabar and South Kanara coasts in southwest India 
at certain seasons, the Madras coast in southeast India, Walvis 
Bay and elsewhere in southwest Africa, the Arabian coast 
between Aden and Perim, the east Japan coast and the East 
Australian coast. In many of these areas, the discoloration 
is an annual occurrence and may be seasonal. 

As in upwelling, a general change of water mass may also 


THE DISTRIBUTION OF DISCOLORED WATER 


occur by a change in current direction. This may also be 
seasonal, as it is in cases of El Nino and Aquaje, off the 
Peruvian coast, 

Before discussing these currents, it would be well to de- 
cribe briefly the normal currents and temperature diStribution 
off the west coast of Peru from Pisco north to the Gulf of 
Guayaquil. 

The Peru current, also known as the Humboldt current, 
which moves from south to north, is a northerly branch of the 
Pacific Antarctic Drift and is particularly noted for its sus- 
tained low temperatures (mean annual temperature close to the 
shore line of central Peru is 10 to 11° C. lower than the 
theoretical value for that latitude). This low temperature 
extends from a point somewhere south of 45° S. to Punta Arina, 
4°40'S., and is caused by the upwelling of the deeper waters. 
Along the northern coast of Peru, the current normally swings 
to the west and converges with the Equatorial Counter Current 
running East. The line of convergence marked by a ‘‘tide 
tip,’’ runs along irregularly from Punta Aguja to the Galapagos 
Islands. The Counter Equatorial Current, which normally turns 
northward along the coasts of Ecuador, Colombia and Central 
America, seasonally swings to the south during January-March, 
bringing a counter current of warm water down the coast of 
Peru, displacing the ordinarily cold water of the Peru Coastal 
Current. This influx of warm water may reach as far south as 
Salaverry, 8°13'S., and even occasionally Pisco. The drastic 
temperature reversat causes widespread mortality of littoral 
invertebrates, fish and even guano birds. The disturbance to 
the planktonic life commonly results in extensive discoloration. 

A similar current change ocurring farther south during the 
months of April through June is called Aquaje. High tempera- 
tures appear off the coast of Peru between the latitudes 9° and 
12°S., caused by the movement inshore of the outlying oceanic 


Destruction of fish by the “Red Tide” off the Gulf Coast. 


waters of high temperature and relatively high salinity. As is 
true of El Nino, the surface waters are usually colored blood 
red. 

Polar waters are often discolored in spring because of the 
abundance of winter-accumulated nutrients. 

These are regular occurrences whose causes are clearly 
marked. Discoloration however, can occur locally and un- 
expectedly even in mid-ocean. Here the causes are obscure. 
Some meteorological quirk or unusual temperature change may 
bring it about. In coastal waters, even the addition of trace 
elements brought down with river runoffs has been considered a 
possible cause. Thus it would seem that regularity of en- 
vironmental cycles brings about a regularity in occurrences of 


WORLD DISTRIBUTION 
OF 
DISCOLORED WATER 


WHITE 

RED 

GREEN 
YELLOW 
BLACK 
DISCOLORED 


SCIENCE AND THE SEA 


discolored water, and where there is a variable ecological 
regime, discoloration occurs only sporadically. 


IMPORTANCE 


The interest in discolored water is not limited to the mariner. 
Inhabitants of shore communities where discolored water recurs, 
find the phenomenon very disturbing. In many of the outbreaks, 
notably the ones in Florida in recent years, the great numbers 
of organisms dying and decomposing in the water produced an 
ugly, evil-smelling scum, and with the rapidly depleted oxygen 
supply killing fishes by the millions and driving them ashore, 
the stench becomes unbearable. The decay and anaerobic 
conditions frequently also contribute to the production of 
hydrogen sulfide gas, the substance with the ‘‘rotten egg smell’’ 
which has blackened the paint on houses near the beach and 
the brightwork on ships passing through it. Because this 
aspect is so conspicuous, the Peruvian outbreaks are called 
“El Pintor’’, ‘The Callao Painter.”’ 

Besides these odors, an irritating vapor was noted in these 
outbreaks which affected the mucus membrane of the nose 
and throat, causing extreme discomfort even to people living 
several miles from the beach. 

Certain of the discoloring organisms have been found to be 
definitely poisonous, and it is believed the mortality among 


the invertebrates and fish is caused by the toxins as well as 
by the oxygen depletion. Although the exact nature of the 
poison is not yet known, it is known to be sufficiently potent 
to be fatal even to humans who may eat oysters, clams, 
mussels, etc., which have the organisms in their stomachs. 

These conditions and the red water may last only a few 
hours, washing away with the tide, or may persist for days 
and weeks until dispersed by the wind, which mixes the water 
and causes the products of the decomposition to sink to the 
bottom, or to be diluted until they are no longer critical. 

The losses to the shell fisheries industries are tremendous 
for, although some fish caught by the tide can swim out of the 
area, the sessile animals can protect themselves only by 
closing their shells. If the outbreak lasts more than a few 
hours they are annihilated. Even among the birds which are 
dependent on marine forms for food, the mortality is extensive. 
The Guano industry in Peru is imperiled regularly by El Nino 
and the Aquaje. 

Not all discoloring organisms are poisonous, of course, and 
discolored water is not always destructive. Some outbreaks 
in fact, would pass unnoticed if they did not occur in a locality 
under the attention of hydrologists. 


ded with an expe 


OCEAN CABLES 
AND 
DEEP-SEA 
TRAWLERS 


By Joseph W. Lermond, Maritime Safety Division, U. S. Naval Oceanographic Office 


From the very beginning of recorded history, and probably be- 
fore, the lives of mankind have been influenced by the oceans. From 
the writings of Homer, which make reference to the sea, to our vastly 
expanded knowledge of the oceans today, man has ventured upon, 
lived, worked, studied, fought on and used the sea for his economic 
gain. Among the vastly expanded oceanic activities is found the 
problem confronting two important industries using the sea today; 
the deep sea fishing industry and that of undersea communications. 
Each is important and provides basic needs or economic wants. Both 
are carried on in a ‘“‘No Man’s’’ wilderness of ocean depths. 

The economic success of both of these industries is subject to 
frequent mishaps in the ocean depths. Communication cables are 
broken and service is interrupted frequently by deep sea trawls. New 
and improved cables are laid out, and broken cables are repaired on 
a continuing basis by the cable companies. Fishing trawls are fouled 
and lost daily in the depths. Service to the public and economic gain 
are the motives of both industries. That these two may better serve 
humanity with a clearer understanding of their mutual interests is 
the objective of this article. 

During recent years the fishing industry and the submarine cable 
companies have been plagued with rising operating costs because of 
the fouling of submarine cables by deep sea trawling gear. This seri- 
ous development poses a problem that is the concern of all maritime 
nations. Solution of the problem with its manifold complexities, is 
indeed, a most formidable task. The annual cost for cable repairs to 
one company alone has been as much as one half million dollars. The 
inconvenience to the public caused by disrupted cable service cannot 
be figured. The number of breaks and the loss of cable service increase 
each year. The cost of labor and materials have also risen steadily. 
The mounting costs incurred by the breakages are significant finan- 
cial losses paid for indirectly by the general public. | Widespread 
knowledge of the problem is desirable, as cooperation between the 


61 


two industries is the only immediate way known to reduce the tre- 
mendous losses in time, labor and material. 

In the early days of the ocean cable industry, fishermen seldom 
damaged cables because most commercial fishing was carried on 
largely with hand lines from dories. With the advent of the steam 
trawler with otter boards, damage to the cables became appreciable. 
The otter trawl at present is still the most efficient method of bottom 
fishing, its general and widespread use has both generated and aggra- 
vated the problem with respect to ocean cable communications. In- 
creased demand for fish, along with the development of refrigerated 
transportation, have influenced the growth of the fishing fleet. These 
fleets now fish in greater depths and constantly extend their area of 
operations. 

The science of communication by cables under the sea has also 
progressed. A telegraph cable previously utilized to carry 55 words 
a minute now carries 300. A transatlantic telephone cable may carry 
as many as 36 two-way conversations simultaneously on each pair. 
Messages now transmitted include high-priority-government, mili- 
tary and diplomatic traffic in addition to the many business and per- 
sonal messages. The prediction 40 years ago that radio would in 
time replace cables as the medium of overseas communication has 
proven to be only partly true. The cables are the “‘work horse’ of 
transoceanic communications and perform a very vital role in the 
world’s business. 

Outbreaks of cable interruptions are often sporadic and may oc- 
cur in an area which has been free of damage for years. In 1946, 
cables landing in Trinity Bay and Conception Bay, Newfoundland, 
were broken a number of times, after being trouble free for 75 years. 
Within 10 weeks three separate breaks on one cable were reported. 
By 1950, the breaks in this area had increased to as many as 15 fail- 
ures in a year, with as much as 130 days of cable time lost. This is a 
serious interruption in service, in addition to being a heavy financial 


SCIENCE AND THE SEA 


loss. Costs for repair of one break run from $2,000 to $20,000 for 
cable alone depending upon the length and type of cable. To include 
the repair ship costs would bring the expense to as much as $50,000 
or more. Service losses on one transatlantic cable off Newfoundland 
may run into thousands of dollars per hour. Costs to the individual 
trawler that fouls a cable are difficult to compute. The fishing gear 
will be replaced by the cable companies if the fisherman will make a 
claim reporting the time, location and depth of the fouling. However, 
a trawler working a long way from its home port would have a con- 
siderable financial loss, above the price of gear alone, if he lost his 
trawl and had to return to port without a catch of fish. 


Investigation of many breaks has revealed miles of trawler-dam- 
aged cable with numerous crushed places, broken armor wires, and 
electrical faults. The increasing number of cases of cable cut with 
an axe, burned with a cutting torch, or parted under strain require 
that the problem be given prompt attention. An examination of the 
background of both the fishing and undersea communication indus- 
tries may lead to a better understanding of the present situation. 


Historically, fishing has played an important role in the econo- 
mies of many nations, and it is the leading industry of at least one 
nation, Norway. Actually fishing is probably the oldest industry 
pursued by man and may even have preceded his efforts at hunting. 
Man’s first venture from shore in a dugout canoe may have been to 
“go fishing’. In medieval times, fish was a most important winter 
food and it still is the ‘‘Lenten Fare’’ of Europe. Fishing fleets were 
also the backbone of many early navies. 

At present, commercial fishing is generally conducted within the 
limits of the 200-fathom curve, although the trend is toward greater 
depths. Fish in any great abundance are not easy to locate or catch 
outside these depths. The fish populations are constantly on the 
move and normally productive fishing grounds are often temporarily 


deserted. Commercial fishermen are alert to these migrations and 
concentrate eagerly wherever fish are found. 

The Grand Banks of Newfoundland, one of the world’s impor- 
tant fishing grounds, is located on the North American continental 
shelf. The fishermen of many nations appear on these banks regu- 
larly. Their fleets of powerful ships are equipped with the latest 
and most modern navigational instruments including loran, Decca, 
gyro compass, fathometer, and specialized devices. Factory ships 
and even hospital ships accompany the fleets. Their fishing gear 
includes otter trawls and nets for taking ground fish such as cod, 
haddock, pollock and redfish. 

The otter trawl is a device for taking bottom fish. It is so con- 
structed that when fully assembled and rigged it will take the shape 
of a huge funnel while traveling along the bottom. Correctly rigged, 
the trawl doors or “‘otter boards’’ keep the mouth of the net open by 
operating at an outward angle from the direction of the towed trawl. 
The fish are swept into the belly of the net by the wings and are 
trapped in the “‘cod end” until the catch is hoisted on deck. The net 
is usually towed at 2 to 3 knots, using two flexible steel wire cables 
about 11/16 of an inch in diameter. The rig weighs about 2 tons and 
a good haul can average about 1 ton of fish. A spare set of gear 
may be rigged for use on the port side of some trawlers but the star- 
board gear is used almost exclusively. Parts from the port side gear 
are used as replacements, when needed. Most trawlers would not 
be able to continue fishing after fouling and losing the working net. 
A replacement will cost $2,500 or more and would usually have to be 
purchased in the home port. 

Since the trawl is operated at depths which preclude a visual ex- 
amination of its workings, it is extremely vulnerable to snags, wrecks, 
rocks, cables, or any other obstruction with which it may become en- 
tangled during its sweep along the bottom. However, it is usually 
profitable to fish in the vicinity of known wrecks. Trawlermen will 


A trawler head-rope and floats being cleared from a communications cable during repair operations aboard a cable 
vessel 


62 


OCEAN CABLES AND DEEP-SEA TRAWLERS 


do this carefully and only with a knowledge of the wreck position 
checked by fathometer and loran or Decca. In fishing near cable 
areas where the exact positions of the cables are not clearly defined, 
an element of risk is introduced. Most trawler skippers are experi- 
enced navigators and as good seamen, they are extremely careful in 
the vicinity of known obstructions. 

The captain and crew of the average trawler do not recieve 
salaries, but share in a division-of the profits after all expenses are 
deducted. An average fishing trip may bring in $10,000 worth of 
fish. The margin of profit is so slender that a broken voyage, caused 
by loss of gear, may spell the difference between a profit and a loss 
for the entire year. 

In 1850, after many years of experimentation and planning, the 
first communication cable was laid between Dover and Calais. The 


cable was soon broken and not successfully reestablished for over a 
year. Seven years later an attempt was made to lay a transatlantic 
cable. This failed when the cable parted in a depth of 2,000 fathoms 
and could not be recovered. In August, 1858, the first successful 
transatlantic cable was laid between Valentia, Ireland and Hearts 
Content, Newfoundland. Service was interrupted by a break in 
deep water after only a few months operation. Transatlantic com- 
munication by cable was finally achieved in 1866. By 1929 there 
were 21 cables across the Atlantic alone and many more elsewhere 
in the world. 

Laying the cable was but one of the many problems to overcome 
before submarine communication could be called a commercial success. 
Sensitive instruments and complex methods of operation gradually 
increased the capacity of each cable. Cable construction details 


The Gifford Grapnel, one of the types used in submarine cable work. 


Landing a cable buoy on deck after repairing a difficult break in deep water 


63 


SCIENCE AND THE SEA 


were perfected for varying usage, depending on location. The ordi- 
nary deep sea type cable is only one inch in diameter and weighs 
about 2 tons per mile. Such cables, brought up after more than 40 
years in deep water, have shown but insignificant signs of deteriora- 
tion. A cable laid near the shore or on shoals has added protection 
against damage by ships anchors and trawling gear. The shore end 


of a cable may thus be up to three inches in diameter and weigh 30 
tons per mile and have a breaking strength of 12 tons or more. By 
Damage 


far, the most common source of damage is fishing trawls. 


caused by underwater slides and volcanic action can be extensive but 
fortunately it is relatively rare. 

The theory of how fouling occurs is based largely on conjecture 
since there are no witnesses and few reports are made. Experiments 
have been made proving that a well constructed and maintained otter 
board can cross a cable laying on the bottom hundreds of times with- 
out fouling. Snagging frequently occurs as the trawler ends the tow 
and swings around to heave in the catch. This maneuver allov’s the 
trawl boards to flatten on the bottom and when the trawl is raised 


Undersea cable damaged by being cut with an axe 


Ocean cable damaged by a break under heavy strain 


A trawl ridden submarine cable showing a kink 


64 


OCEAN CABLES AND DEEP-SEA TRAWLERS 


the leading edge of the otter board may pass under a cable. Where 
the cable lies flat on an even bottom, fouling will not generally occur, 
but where tension remains in the cable over a slight bottom depres- 
sion, fouling is likely. At times excessive slack is the cause of fouling 
and unfortunately slack in some form is bound to exist wherever a 
repair has been made, and it is this slackness resulting from a repair 
which makes the cable more vulnerable than before. 

That broken cables have long been an international problem is 
indicated by the Articles of the International Convention held in 
1884. The Articles which follow were approved by the member 
nations and are still in force, but they have done little during the 
years to alleviate the situation. 


International Convention of March 14. 1884 
for the protection of submarine cables 


His Excellency the President of the United States of noe 
America,.. .[the heads of state of Germany, Argentine Con- t a - Sra ate ere 
federation, Austria-Hungary, Belgium, Brazil, Costa-Rica, r otter board ready for release at the gallows. 
Denmark, Dominican Republic, Spain, United States of ~ 
Colombia, France, Great Britain, Guatemala, Greece, Italy, 
Turkey, Netherlands, Persia, Portugal, Roumania, Russia, 
Salvador, Servia, Sweden and Norway, and Uruguay], 
desiring to secure the maintenance of telegraphic communi- 
cation by means of submarine cables, have resolved to con- 
clude a convention to that end, and have appointed as their 
Plenipotentiaries, to wit: 

...{Maming the representatives from the various coun- 
tries] 

Who, after having exchanged their full powers, which 
were found to be in good and due form, have agreed upon 
the following articles: 

ARTICLE I. 


The present Convention shall be applicable, outside of 
the territorial waters, to all legally established submarine 
cables landed in the territories, colonies or possessions of 
one or more of the High Contracting Parties. 


ARTICLE II. 


The breaking or injury of a submarine cable, done will- 
fully or through culpable negligence, and resulting in the to- 
tal or partial interruption or embarrassment of telegraphic 
communication, shall be a punishable offense, but the pun- 
ishment inflicted shall be no bar to a civil action for damages. 

This provision shall not apply to ruptures or injuries 
when the parties guilty thereof have become so simply with 
the legitimate object of saving their lives or their vessels, 
after having taken all necessary precautions to avoid such 
ruptures or injuries. 

ARTICLE III. 

The High Contracting Parties agree to insist, as far as 
possible, when they shall authorize the landing of a sub- 
marine cable, upon suitable conditions of safety, both as 
regards the track of the cable and its dimensions. 


ARTICLE IV. 


The owner of a cable who, by the laying or repairing 
of that cable, shall cause the breaking or injury of another 
cable, shall be required to pay the cost of the repairs which 
such breaking or injury shall have rendered necessary, but 
such payment shall not bar the enforcement, if there be 
ground therefore, of article II. of this Convention. 


¥ 


Hoisting the “Cod-end”’ of the net. 


ARTICLE V. 


Vessels engaged in laying or repairing submarine cables 
must observe the rules concerning signals that have been or 
shall be adopted, by common consent, by the High Contrac- 
ting Parties, with a view to preventing collisions at sea. 

When a vessel engaged in repairing a cable carries the 
said signals, other vessels that see or are able to see those 
signals shall withdraw or keep at a distance of at least one 
nautical mile from such vessel, in order not to interfere with 
its operations. 

Fishing gear and nets shall be kept at the same distance. 

Nevertheless, a period of twenty-four hours at most 


shall be allowed to fishing vessels that perceive or are able $s po ee Bae Pt 
to perceive a telegraph ship carrying the said signals, in order Hauling in on wires at the end of a run 


65 


SCIENCE AND THE SEA 


that they may be enabled to obey the notice thus given, and 
no obstacle shall be placed in the way of their operations 
during such period. 

The operations of telegraph ships shall be finished as 
speedily as possible. 


ARTICLE VI. 


Vessels that see or are able to see buoys designed to 
show the position of cables when the latter are being laid, 
are out of order, or are broken, shall keep at a distance of 
one quarter of a nautical mile at least from such buoys. 

Fishing nets and gear shall be kept at the same distance. 


ARTICLE VII. 


Owners of ships or vessels who can prove that they have 
sacrificed an anchor, a net, or any other implement used in 
fishing, in order to avoid injuring a submarine cable, shall 
be indemnified by the owner of the cable. 

In order to be entitled to such indemnity, one must pre- 
pare, whenever possible, immediately after the accident, in 
proof thereof, a statement supported by the testimony of 
the men belonging to the crew; and the captain of the ves- 
sel must, within twenty-four hours after arriving at the first 
port of temporary entry, make his declaration to the com- 
petent authorities. The latter shall give notice thereof to 
the consular authorities of the nation to which the owner of 
the cable belongs. 


ARTICLE VIII. 


The courts competent to take cognizance of infractions 
of this convention shall be those of the country to which the 
vessel on board of which the infraction has been committed 
belongs. 


It is, moreover, understood that in cases in which the 
provisions contained in the foregoing paragraph cannot be 
carried out, the repression of violations of this Convention 
shall take place, in each of the contracting States, in the 
case of its subjects or citizens, in accordance with the general 
rules of Penal competents established by the special laws of 
those States, or by international treaties. 


ARTICLE IX. 


Prosecutions on account of the infractions contempla- 
ted in Articles II., V. and VI. of this Convention shall be 
instituted by the State or in its name. 


ARTICLE X. 


Evidence of violations of this Convention may be ob- 
tained by all methods of securing proof that are allowed by 
the laws of the country of the court before which a case has 
been brought. 

When the officers commanding the vessels of war or the 
vessels specially commissioned for that purpose, of one of 
the High Contracting Parties, shall have reason to believe 
that an infraction of the measures provided for by this Con- 
vention has been committed by a vessel other than a vessel 
of war, they may require the captain or master to exhibit 
the official documents furnishing evidence of the nation- 
ality of the said vessel. Summary mention of such exhibi- 
tion shall at once be made on the documents exhibited. 

Reports may, moreover, be prepared by the said offi- 
cers, whatever may be the nationality of the inculpated ves- 
sel. These reports shall be drawn up in the form and in the 
language in use in the country to which the officer drawing 
them up belongs; they may be used as evidence in the 
country in which they shall be invoked, and according to 
the laws of such country. The accused parties and the wit- 
nesses shall have the right to add or cause to be added there- 
to, in their own language, any explanations that they may 
deem proper; these declarations shall be duly signed. 


ARTICLE XI. 


Proceedings and trial in cases of infractions of the pro- 
visions of this Convention shall always take place as sum- 
marily as the laws and regulations in force will permit. 


ARTICLE XII. 


The High Contracting Parties engaged to take or to 
propose to their respective legislative bodies the measures 
necessary in order to secure the execution of this Conven- 


The otter trawl. 


OCEAN CABLES AND DEEP-SEA TRAWLERS 


tion, and especially in order to cause the punishment, either 
by fine or imprisonment, or both, of such persons as may 
violate the provisions of Articles II., V. and VI. 


ARTICLE XIII. 


The High Contracting Parties shall communicate to 
each other such laws as may already have been or as may 
hereafter be enacted in their respective countries, relative 
to the subject of this Convention. 


ARTICLE XIV. 


States that have not taken part in this Convention shall 
be allowed to adhere thereto, on their requesting to do so. 
Notice of such adhesion shall be given diplomatically, to the 
Government of the French Republic and by the latter to the 
other signatory Governments. 


ARTICLE XV. 


It is understood that the stipulations of this Conven- 
tion shall in no wise affect the liberty of action of bellig- 
erents. 


ARTICLE XVI. 


This Convention shall take effect on such day as shall 
be agreed upon by the High Contracting Parties. 

It shall remain in force for five years from that day, 
and, in case none of the High Contracting Parties shall have 
given notice twelve months previously to the expiration of 
the said period of five years, of its intention to cause its ef- 
fects to cease, which shall continue in force for one year, and 
so on from year to year. 

In case of one of the Signatory Powers shall give notice 
of its desire for the cessation of the effects of this Conven- 
tion, such notice shall be effective as regards that Power 
only. 


ARTICLE XVII. 


This Convention shall be ratified; its ratifications shall 
be exchanged at Paris as speedily as possible, and in one 
year at the latest. 

In testimony whereof, the respective Plenipotentiaries 
have signed it, and have thereunto affixed their seals. 

Done in twenty-six copies, at Paris, this 14th day of 
March, 1884. 

[Signatures of the representatives follow.] 


Measures taken to minimize damage to ocean cables have not 
proven effective. None have reduced the damage appreciably. The 
1884 International Convention, and later action by participating 
countries making it a misdemeanor to willfully damage or break a 
submarine cable, has had no visible effect. An attempt around 1920 
to persuade trawler fishermen to use otter boards of an improved 
design, recommended as better able to avoid fouling, met with no en- 
thusiasm. The standing offer by cable companies to reimburse fish- 
ermen for gear abandoned to save cables has probably been most 
impressive as a gesture of mutual cooperation. 

Some of the measures listed below may serve to alleviate the 
situation: 


(a) Chart cable positions on the best scale navigation 
charts. This is now being done and these charts may 
be obtained free of charge by writing to any of the fol- 
lowing: 

Cable Damage Committee 
Mercury House, Theobald’s Road 
London W.C. 1, England 


The Western Union Telegraph Company 
International Communications 
General Plant Engineer 


LEGEND 
OTTER TRAWLERS 


LONG LINERS AND 
DORY VESSELS 


OTHER SMALL FISHING 
CRAFT 


CABLE AREAS 


. a 
~ S 
WN SS 
PN: 


TN 


“ 


Grand Banks of Newfoundland showing the cable areas and a typical concentration of fishing vessels. 


67 


SCIENCE AND THE SEA 


60 Hudson Street 
New York 13, N.Y., U.S.A. 


The American Telephone & Telegraph Co. 
Long Lines Department 

32 Avenue of the Americas 

New York 138, N.Y., U.S.A. 


Commercial Cable Company 
Marine Superintendent 

67 Broad Street 

New York 5, N.Y., U.S.A. 


(b) Ifa cable is hooked the fisherman should cut his gear 


(c) 


(d) 


and forward a claim to any of the above who will see 
that the claim is forwarded to the company whose cable 
is involved. 

Trench the cable in areas where damage is likely to oc- 
cur. This has already proven effective in relaying four 
transatlantic cables across the active trawler area 
southwestward of Ireland. Unfortunately, the rocky 
bottom and strong current off Newfoundland make the 
problem of burying the cables in that area extremely 
difficult and the means to accomplish this are not now 
available. 

Remove abandoned cables. Cable companies have re- 
placed the original cables with more heavily armored 
types in fishing areas, but numerous abandoned cables 
remain on the bottom and area hazard to the fishermen. 


YOR 1 ePeR gE 


— 
ST 


Some cables carry voltages in excess of 2,000 and any attempt 
to cut these on deck would be extremely hazardous. 

A pressing need for closer cooperation between the fishing and 
communication industries is evident. Fishermen lose far too much 
time and gear because of cables laid in fishing areas. Cable breaks 
and service interruptions are far too frequent to be condoned. The 
development of an improved trawl gear, invulnerable to cable fouling, 
would be a step in the right direction. Diversion of the cables to 
waters clear of fishing areas, or into unified routes which could be 
charted across larger fishing areas, might appear to lead to a satisfac- 
tory solution. However, this has already been attempted by one cable 
company which spent considerable time and money for major re-rout- 
ings of the cables northward on the advice of qualified fisheries experts 
only to find that the fish also moved northward. 

New factors which might revolutionize both industries may 
materialize in the future. The number of cables laid across fishing 
areas may decrease with the use of modern coaxial design cable using 
submerged repeaters. Improvement in fish detection technique may 
change fishing methods. Another development which appears pro- 
mising is the use of mid-water trawling or otter boards that swim. 
This would not only avoid damage to the cables but would also greatly 
reduce the power expended by towing present day otter boards along 
the bottom. This waste of power amounts to as much as 30 percent 
of the trawler’s main propulsion. But, while waiting for these de- 
velopments, a practical policy of eliminating the present hazards and 
inconveniences should be undertaken. The problem of compatibility 
must be solved in an effort to serve the best interests of both the fish- 
ing and ocean cable industries. 


x 


A diesel powered trawler proceeding seaward from a New England port 


68 


®) 


CASE 1 


By Frederick W. Fricker 
Maritime Safety Division 
U.S. Naval Oceanographic Office 
Washington, D. C. 20390 


INTRODUCTION 


In a previous Pilot Chart Article, titled More 
About Collisions, the results of an examination of 
ship casualties for the years 1957 through 1961 
indicated that, on an average, approximately 20 
percent were COLLISIONS. In the effort to 
establish a trend since that period and, hopefully, 
report an improvement in the COLLISION rate, 
a similar study was conducted for the decade 1958 
through 1967. The statistics used in both studies 
were from the annual reports issued by the Liver- 
pool Underwriters’ Association, which lists all 
casualties reported for vessels of 500 gross tons 
and over. Unfortunately, no improvement was 
indicated by the recent study which again disclosed 
that an average of approximately 20 percent of 
all casualties occurring during the 10-year period 
were COLLISIONS. The term all casualties 
includes ship damage or loss due to weather, 
groundings, fires and explosions, etc., as well as 
collisions. Since the study showed that, on an 
average, more than one third of all ships considered 
suffered a casualty of some sort during the period, 
it can be said that approximately seven percent 
of the world’s fleet was involved in a collision 
during each of the years specified. 

Judging by the apparent consistency with 
which collisions occur each year, the annual aver- 


69 


COLLISIONS—1969 


age thus provided could conceivably be used as a 
forecast for future years. Carrying the hypothesis 
further, we could say that almost seven percent of 
the world’s fleet, roughly between 1,700 and 1,800 
ships, will suffer a collision during the coming 
year. It would mean that approximately one ship 
in every 15 would be the victim of a collision in 
any given year. This is indeed a matter of serious 
concern. 

Fortunately, mariners have at their disposal 
the time and the means to control, for the most 
part, the destiny of their own vessels and conse- 
quently to improve the casualty records of the 
future. They should start by accepting the fact 
that the majority of collisions occur as the result 
of a few human shortcomings. A study of recent 
collision cases is considered to be a good method 
to identify these frailties of the mariner. As the 
philosopher Publilius once said, “He who gains 
wisdom from the mistakes of others is truly wise.”’ 

The following cases are, therefore, presented 
to focus attention on some of the shortcomings 
that have contributed to collisions. They were 
particularly selected because each of the incidents 
occurred in what might be described as the classic 
situation, the head-to-head meeting during limited 
visibility, and because all of the ships implicated 
were equipped with operational radar. Although 
all are based on authentic incidents, none of the 
cases is to be construed as being a complete 
report, for facts considered immaterial to the 
purpose of this article were intentionally omitted. 


SCIENCE AND THE SEA 


The opinions and conclusions expressed in the 
analyses are those of the author and are intended 
to place maximum emphasis on the lessons to be 
learned. Serious consideration of these lessons by 
all mariners involved in the navigation of ships 
could lead to a significant reduction in the number 
of collisions in the future. 


CASE 1 


The principals in this case were two American 
dry-cargo vessels that collided in the Yellow Sea 
off the west coast of Korea during a period of 
restricted visibility. The weather at the time 
consisted of a southwesterly wind, force 3-4, with 
light rain, mist, and patchy fog. The range of 
visibility was estimated to be less than a mile. A 
slight to moderate sea was running with very 
little swell. Both vessels were equipped with radar 
which was reported to have been in good operation 
at the time of the casualty. 


NARRATIVE 
SHIP A 


Ship A was enroute from Inchon, Korea, to 
Pusan, Korea, with general cargo. After departure 
the master maintained the conn until the ship was 
clear of the island group just south of Inchon. 


70 


CASE 2 


Shortly after midnight the ship entered the 
relatively open waters of the Yellow Sea, where- 
upon the master relinquished the conn to the mate 
of the watch and went below. 

The vessel proceeded southward at 16 knots 
on a course of 186°T. Due to the limited visibility 
and the unexpected presence of local fishing craft, 
the watch officer frequently scanned the radar 
screen which was set on the 8-mile scale. At 0324 
he thus observed a large target, Ship B, which he 
estimated to be dead ahead (186°T) at a distance of 
approximately 8 miles. This fix as well as the 
subsequent radar fixes of Ship B by Ship A proved 
to be erroneous by 11°E to 15°E in bearing and 
consistently 114 miles in excess of that which can 
be substantiated by reconstruction. 

One minute later, obviously unaware of his 
radar’s error, the watch officer observed that the 
target bore 184°T, range 7.5 miles. Believing this 
contact to be a large, fast ship because of its pip 
size and high closing speed, the watch officer 
changed course to 209°T. At 0328 he calculated 
that the target bore 183°T, 5.5 miles distant. 
Around 0330, again noting the speed at which the 
target was closing and that the bearing had not 
changed appreciably, the watch officer changed 
course to 229°T. At this time the two ships were 


COLLISIONS—1969 


about four miles apart. 

At 0333, Ship B was sighted visually close 
aboard off the port bow and on a collision course. 
Shortly after the sighting the watch officer 
ordered Right 20° Rudder followed by Hard Right. 
He then sounded the general alarm. Collision 
occurred within a minute as Ship B knifed into 
the port side of Ship A. At the time Ship A was 
still making turns for 16 knots. 


SHIP B 


Ship B was enroute from Kobe, Japan, to 
Inchon, Korea. About 0040 the master set a course 
of 008°T and instructed the watch officer to give 
all ships a wide berth. He then went below for 
the night. During the next three hours the watch 
officer made numerous course changes to avoid 
fishing crafl. From several radar fixes it was 
estimated that Ship B was making good 20 knots 
over the ground. About 0300 the radar was 
switched from the 8-mile scale normally in use to 
the 20-mile scale to get a fix on land features. 
No targets that might have been ships were 
detected outside of the 8-mile range. At 0315 the 
radar was again switched to the 20-mile scale, but 
no target that might have been Ship A was noted. 

Sometime between 0315 and 0320 radar 


CASE 3 


71 


CASE 4 


contacts believed to be more fishing vessels were 
picked up off the port bow, and the watch officer 
ordered a substantial course change to starboard. 
After estimating that the ship was clear he 
returned to the base course of 008°T. 

At approximately 0328 the watch officer 
thought he detected a radar target bearing 018°T 
on the 4-mile range ring. He changed course to 
000°T in case the target was another fishing 
vessel, and estimated that it would pass about 1 
mile off the starboard side. At 0330 the watch 
officer again switched to the 20-mile scale to get 
a fix. Upon switching back to the 8-mile scale, 
he noticed that the target now presented a much 
larger pip. Suspicious of the contact the watch 
officer ordered the helmsman to come left to 
course 350°T and stepped out into the starboard 
bridge wing. He then saw several white lights 
bearing two points on the starboard bow and 
knew immediately that he was looking at a large 
ship. Quickly estimating that it was about 2 
miles distant he ordered Hard Left Rudder. Next, 
he placed the telegraph on full astern and called 
the master on the voice tube. Without waiting 
for a reply he returned to the bridge wing. 
Seconds later the bridge of Ship A loomed forth, 
broad on the starboard bow. Collision followed 


SCIENCE AND THE SEA 


minutes later as the bow of Ship B penetrated 
deeply into the port side of Ship A. 


ANALYSIS 

The primary causes of this collision were the 
excessive speed at which both ships were navi- 
gated during conditions of limited visibility and 
the failure by the watch officer of each vessel 
involved to reduce speed or stop upon detecting 
another vessel ahead whose course and intention 
were unknown. In each instance the responsible 
officer was guilty of violating Rule 16. A con- 
tributing factor which certainly should be cited 
was Ship A’s overreliance on faulty radar infor- 
mation. 

As early as 12 minutes before the casualty, 
Ship A’s conning officer had detected Ship B and 
recognized it as a large ship. One minute later 
he further established that it was closing at high 
speed and made the first of two substantial course 
changes to the right in the effort to avoid a close 
quarter situation. Had Ship B actually been in 
the relative position reported, that is, dead ahead 
when first detected, the evasive course changes 
made by Ship A would probably have had the 
desired effect. Unfortunately, such was not the 
case. A reconstruction of the courses steered by 
the two ships during the final hour indicates that 
Ship B’s track was westward of Ship A’s. At 
0324, therefore, Ship B would have been about one 
point on Ship A’s starboard bow. Subsequent 
events tend to support this contention. The obvious 
misinterpretation of radar information by Ship A, 
due probably to the large pip size on the 8-mile 
scale and the now apparent miscalibration of the 
radar set, led to the watch officer’s decision to 


72 


No case cited in this area. 


turn to the right directly into the path of Ship B. 
Here is a perfect example of the fallacy of placing 
too much reliance on radar data. 


Even five minutes before the casualty, Ship 
A’s watch officer had a further warning of the 
impending danger when he noted that Ship BS 
bearing had not changed appreciably. He failed 
to heed this last warning and permitted the ship 
to continue at top speed toward the approaching 
vessel. 

Ship B’s watch officer was, of course, bliss- 
fully unaware of Ship A’s existence until less than 
five minutes before the tragedy. Here was a large 
ship, being navigated almost solely by radar, pro- 
ceeding through open water at high speed during 
conditions of limited visibility, and the watch offi- 
cer was employed, for the most part, in avoiding 
local fishing craft. So occupied was he in doing so, 
that rarely was his radar scope set to anything 
but the 8-mile range, contrary to the tenets of 
Rule 29, keeping a proper lookout. His turns to 
the left, upon discovery of Ship A, were probably 
correct tactics under the circumstances, but the 
ship’s high speed, unchanged until moments before 
impact, placed it in extremis before a truly 
effective plan could be formulated. 


CASE 2 


The principals in this case were two dry-cargo 
vessels which collided in heavy fog in the Pacific 
Ocean approximately 10 miles westward of Cape 
San Martin. California. The visibility at the time 
of impact was variously reported as ranging from 
zero to one-half mile. The wind was northwesterly, 
force 4 to 5, sea conditions moderate with negli- 


COLLISIONS—1969 


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gible coastal current. Both vessels were equipped 
with radar, reportedly in good operating condition 
prior to, and at the time of, the casualty. A radar 
plot was not maintained by either ship. i 
NARRATIVE 
SHIP A 


Ship A was enroute from Oakland, California. 


73 


to Los Angeles, California, with general cargo. 
Departure was taken at the San Francisco Light- 
ship at 2300, and the vessel proceeded southward 
at 21 knots on a course of 148°T, following the 
usual coastwise steamer track. Before going 
below for the night the master left orders to alter 
course as necessary to stay within a mile of the 
designated track line. 


SCIENCE AND THE SEA 


The midwatch was uneventful, but at 0400 
the relieving watch officer obtained a radar fix 
which indicated that the ship was about one mile 
seaward of the track. He, therefore, changed 
course to 147°T to bring the ship gradually back 
to the desired track line. Shortly thereafter 
heavy fog set in, reducing visibility to less than 
one mile. The master and the engineer on watch 
were notified, and the engine was placed on 
standby. The automatic fog signal was activated, 
but no change in speed was made. A few minutes 
later the master arrived on the bridge to check 
for radar contacts, but none was observed. After 
spending about five minutes on the bridge he went 
below again where he remained until the collision. 
At 0443, after another radar fix placed the vessel 
seaward of the track line, the watch officer 
changed course to 144°T. 

Ship B was first observed at 0447 as a radar 
contact bearing 003° relative at a distance of 
approximately 8 miles. At 0449 another radar fix 
was obtained which plotted seaward of the desired 
track, and the course was again changed to the 
left to 139°T. At 0450 Ship B appeared on radar 
to be about 012° relative at a distance of 6 miles. 
The watch officer alerted his bow lookout that a 
ship was off the starboard bow and cautioned him 
to keep a sharp lookout. He failed, however, to 
notify the master or to reduce speed. At 0457 the 
watch officer again observed Ship B on the radar 
screen and noted that the target appeared to be 
bearing 020° relative at 2 miles before being lost in 
the sea return. He then went out on the starboard 
bridge wing to listen for fog signals and heard the 
bow lookout sound the bell signal indicating a 
vessel to starboard. At about 0458 the watch 
officer heard one prolonged blast close aboard. 
Moments later Ship B’s port side light, masthead 
light, and range lights suddenly appeared out of 
the fog about 003° relative to Ship A at less than 
1,000 yards. The watch officer ordered Hard Right 
and put the engineroom telegraph on full astern. 
One short blast was sounded, followed by several 
more. Collision occurred seconds later with Ship A 
just beginning to answer her right rudder. Ship B 
penetrated Ship A to a distance of 40 feet on the 
starboard side of No. 2 hold. 


SHIP B 


Ship B was enroute from La Libertad, El 
Salvador, to San Francisco, California. On the 
morning of the collision the ship was proceeding 
northward along the coastal route on a course of 
334°T at a speed of 16 knots. At 0345, when the 


74 


ship drew abeam of Pt. Piedras Blancas Light, a 
heavy fog set in. The master was informed of the 
situation, and he reduced speed to 12 knots. The 
telegraph was placed on standby, the engineroom 
notified, fog signals started, and a lookout posted 
on the forecastle. The course at this time was 
334°. 

At 0445 a target was picked up on radar 
bearing 357° relative, range about 7 miles. The 
contact was reported to the master who changed 
course to 345°T. The limit of visibility at this 
time was approximately one mile. A few minutes 
later the target was observed at a range of 4.5 
miles, but no bearing was obtained. At approxi- 
mately 0455 the watch officer scanned the radar 
screen and determined that the range was 2 miles 
and that the bearing appeared to be opening. 
Shortly thereafter the master assumed the conn. 

At 0458 the bow lookout sounded the bell 
signal indicating a ship off the port bow, and the 
master ordered Right 20° Rudder. Less than a 
minute later Ship A appeared out of the fog, her 
port and starboard side lights, masthead light, and 
range lights all visible. The master immediately 
ordered Hard Right and sounded one short blast. 
Collision occurred seconds later as the bow of 
Ship B tore into the starboard side of Ship A. 
At the time of impact Ship B was still making 
turns for 12 knots. 


ANALYSIS 


The primary cause of this collision was the 
excessive speed at which both ships were navi- 
gated during conditions of extremely restricted 
visibility. Equally responsible was the failure of 
the watch officer on each vessel to stop their 
engines and navigate with caution after hearing, 
apparently forward of the beam, the fog signal of 
a vessel the position of which is not ascertained. 
Both citations are, of course, in violation of Rule 
16. Contributing greatly to the casualty was the 
amazingly casual manner in which personnel of 
both ships utilized available radar information. 

Ship A, proceeding at an unusually high rate 
of speed, encountered heavy fog shortly after 0400. 
Neither the master nor the watch officer felt it 
necessary to reduce speed, presumably secure in 
the knowledge that radar data was available. 
Then, after detecting Ship B in such a position as 
to indicate a meeting situation was probably 
developing, the watch officer altered course to the 
left for no better reason than to return to the 
track line. However, the close-quarter situation 
could still have been avoided if the radar had been 
properly used, for what the watch officer saw on 


COLLISIONS—1969 


(CONTINUED ON CHART 5020) 


CASE 


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the screen somehow deluded him into believing 
that the bearing of Ship B was opening to the 
right. A reconstruction of both tracks tends to 
indicate that the bearing could not have changed 
significantly during the 12 minutes prior to the 
collision. 


Ship B’s personnel wisely reduced speed soon 
after the fog set in, but in view of the state of 
visibility even 12 knots could not be considered a 
moderate speed. If the master was depending on 
radar to alert him of dangers ahead it was not 
evident in his subsequent actions. Ship A was 


75 


first detected at a range of 7 miles, a relatively 
short distance if it develops, as it did, that the 
target is on a reciprocal course. Some five minutes 
transpired before the next radar observation was 
made, and it revealed that the target was only 4.5 
miles away. This alone was a clear indication that 
the closing speed was great, yet no bearing was 
taken at the time. The casualty could still have 
been avoided, however, if the last radar observa- 
tion, taken four minutes before impact, had 
correctly imparted the fact that the two ships 
were on a collision course. 


SCIENCE AND THE SEA 


CASE 3 


The principals in this case were a dry-cargo 
vessel and a bulk carrier which collided during a 
period of restricted visibility in the Atlantic Ocean 
approximately one mile south of Chesapeake Bay 
Entrance Lighted Whistle Buoy 2CB. The 
casualty occurred in international waters, and both 
ships were credited with having been displaying 
proper navigation lights and sounding appropriate 
fog signals. The weather at the time was foggy 
with visibility from 500 yards to one mile. The 
wind was from the ESE, force 5. 

Both vessels were equipped with radar, and 
both reported that it was in use and functioning 
properly at the time of the collision. 


NARRATIVE 
SHIP A 


Ship A departed Baltimore, Maryland, with 
general cargo enroute to Jacksonville, Florida. 
After completing an uneventful transit down the 
Chesapeake Bay, the pilot disembarked at the 
Maryland Pilot Boat anchored about 1.8 miles 
east-northeastward of Cape Henry Light. The 
weather consisted of patchy fog with visibility 
ranging between 500 and 4,000 yards. Following 
the pilot’s departure at 2051, the master set a 
course of 128°T to pass south of Chesapeake Bay 
Entrance Buoy 2CB, some 9 miles distant. A 
lookout was stationed on the bow, and the pre- 
scribed fog signals were being sounded. The 


engines were placed on standby. On the bridge 
with the master, who was conning, were the watch 
officer and a helmsman. The master frequently 
observed the radar screen which was set on the 
relative motion display. During the passage from 
the pilot boat to Buoy 2CB, several course and 
speed changes were made due to conditions of 
visibility and the avoidance of inbound traffic. 

According to the master’s account, Ship Bwas 
observed at 2124 as a radar contact bearing 001° 
relative at a distance of 4 miles. The master 
incorrectly estimated the contact to be about 1 
mile east of Buoy 2CB. Shortly after this initial 
contact, Ship B was observed to have moved from 
Ship A’s starboard bow to close on her port bow. 
From this apparent relative movement it was 
assumed that Ship B was inbound and would pass 
safely to port with a CPA of about 1 mile. No 
attempt was made to plot the radar contact to 
determine its true course and speed. 

At 2127, Ship A increased speed to approxi- 
mately 12 knots (maneuvering speed). Shortly 
thereafter, the master, watch officer, and bow 
lookout all heard fog signals off the port bow. 
The master assumed that the signals were being 
made by the radar contact he’d been observing, 
thus confirming his previous deduction that a safe 
port-to-port passing would take place. At 2130, a 
glare of lights was seen broad on the port bow in 
which the master and watch officer saw what 
appeared to be the range lights of Ship B. From 
the position of the lights, they determined that 


BsSerenesBecpecsesansamee bans. 


76 


COLLISIONS—1969 


A freighter limps back to port after receiving collision damage on the starboard side, amidships. 


they were looking at the port bow. Although 
neither officer saw a red side light, both felt that 
a port-to-port passing situation still existed. At 
2135, Ship A passed Buoy 2CB abeam to port. A 
half minute later, the watch officer shouted that 
he saw Ship B’s green side light. Convinced that 
Ship B had come left while he had been observing 
the radar screen, the master immediately respond- 
ed by ordering Right Full Rudder and Full Speed 
Astern. Whistle signals for each of these maneu- 
vers were sounded. At 2139, Ship A was presumed 
dead in the water and All Stop was ordered. 
During the ensuing minute the distance between 
the two ships closed rapidly. At 2140, Ship A’s 
master realized that a collision was imminent and 
decided to turn his vessel more to starboard to 
possibly limit the expected contact to a glancing 
blow. With the rudder still hard right, Half Speed 
Ahead was ordered. Collision occurred seconds 
later. 


SHIP B 


17 


Ship B was approaching Chesapeake Bay En- 
trance on the last leg of a voyage from Hamburg, 
Germany, to Norfolk, Virginia. At 2105, with the 
ship about 3 miles southwest of Chesapeake Light, 
the course was changed to 260°T. The master 
intended to take the ship to a point about 4 mile 
south of Chesapeake Bay Entrance Buoy 2CB 
before shaping a course for the pilot station. 
Bridge personnel consisted of the master, watch 
officer, and helmsman, and a lookout was posted 
on the bow. At 2119 speed was reduced to slow 
ahead due to low visibility. The engineroom was 
on standby. Visibility was between zero and 75 
yards in patchy fog. About 2126 speed was 
increased to half-ahead (approximately 8 knots) 
because steering had become sluggish. Both the 
master and watch officer intermittently checked 
the radar screen which was showing a relative 
presentation on a 12-mile scale. 

As Ship B approached Buoy 2CB, several 
radar contacts were observed bearing 045° relative 
at a distance of about 7 miles. These contacts 


SCIENCE AND THE SEA 


The unmistakable imprint of another ship’s bow torn into the forecastle of this freighter, is mute evidence 
of the force of impact. 


were presumed to be outbound vessels from the 
Virginia Capes. No plot was started for any of 
the contacts to determine their true course and 
speed. Several minutes before the collision 
occurred, the watch officer observed that one 


78 


contact, Ship A, had closed to a range of 2 to3 
miles and was still bearing 045° relative. He 
failed, however, to inform the master of this fact 
or to take any action of hisown. At 2136 an object 
was sighted on the starboard bow which appeared 


COLLISIONS—1969 


to be a large, light-colored mass or cloud. Neither 
officer was able to distinguish any navigational 
lights, nor were any fog signals heard coming from 
its direction. The master ordered Left Full Rudder 
and sounded two short blasts. At 2138 the engines 
were stopped; then backed full. Three short 
blasts were sounded. No one on Ship B heard any 
signals from the contact except one group of 3 
short blasts shortly before the collision. At 2140 
the starboard bow of Ship B made contact with 
the port side of Ship A, amidships. At the time 
of impact Ship B formed an angle with Ship A of 
about 45 degrees tending aft. 


ANALYSIS 


The primary cause of this casualty was the 
violation of Rule 16(c) by the masters of both 
vessels. Each of these officers detected the other 
ship in ample time to comply with Rule 16, but 
neither took early and substantial action to avoid 
a close quarter situation, nor did they stop their 
engines and then navigate with caution until the 
danger of collision was over. 

A factor which contributed greatly to the 
casualty was the failure of personnel of both ships 
to evaluate properly or to analyze the radar 
information available. Neither vessel attempted 
to maintain a graphic plot of radar data and, 
therefore, were never fully aware of the other’s 
course and speed prior to the collision. During 
the passage from the pilot station to Buoy 2CB, 
Ship A had maneuvered to the right several times, 
by the master’s own admission. After each such 
maneuver, he attempted to return to the track 
line by steering to the left of base course. It is 
evident that Ship A’s heading was well to the 
left of base course when the master first observed 
Ship B on the starboard bow. It is also evident 
that subsequent changes in Ship B’s relative 
bearing must have been the result of heading 
changes in Ship A. Parenthetically, this situation 
exemplifies the risk involved in using a relative 
motion display without a clear understanding of 
what it actually indicates. 

Ship B’s radar watch left much to be desired. 
After the initial contact, the master apparently 
left the job up to the watch officer. The latter’s 
failure to alert the master or take action himself 
after he observed the proximity and unchanging 
bearing of Ship A minutes before the collision is, 
of course, inexcusable. 

In retrospect, it appears likely that the 
collision might have been averted had Ship B 
elected to turn right instead of making the always 


79 


risky turn to the left. Here again, the maintenance 
of a plot would have provided the master with 
some knowledge of Ship A’s relative movement 
and aided him in taking proper avoiding actions. 

There was some evidence that Ship B was 
exhibiting lights which could have been, and 
probably were, mistaken for prescribed navigation 
lights. 


CASE 4 


The principals in this case were two American 
ships that collided in the vicinity of West Penob- 
scot Bay, Maine, during a period of dense fog. A 
light breeze was blowing from the south and there 
was a slight southerly sea running at the time of 
the casualty. The tide was flooding with high 
water at Monhegan Island scheduled at 2038. 


NARRATIVE 
SHIP A 


Ship A, enroute to Linden, New Jersey, 
departed Buckport, Maine, at 1420. The vessel 
proceeded down the Penobscot River and entered 
West Penobscot Bay using various courses and 
speeds under the direction of a pilot. At approxi- 
mately 1724 the engineroom was placed on standby 
and the ship’s engine speed reduced to half-ahead 
due to fog closing in. The vessel commenced 
sounding fog signals, and a lookout was stationed 
in the bow. 

With the master on the bridge, the vessel 
continued at half-ahead (about 9 knots) on a 
course of 180°T down West Penobscot Bay, 
stemming the flood tidal current. At 1748 a radar 
bearing indicated that Two Bush Island Lighted 
Whistle Buoy TBI was abeam approximately 4 
mile to port. The course was altered to 240°T in 
order to enter Two Bush Channel. A short time 
after steadying on this course a large target was 
noted on the radar screen about seven or eight 
miles ahead. The master and pilot together esti- 
mated that the target was on a generally northeast 
course heading toward Two Bush Channel and that 
it was a few degrees on the starboard bow of 
Ship A. 

At approximately 1753 the pilot changed 
course to 235°T intending to make a starboard-to- 
starboard passing with the approaching vessel and 
to leave Two Bush Ledge Lighted Gong Buoy to 
starboard. Sometime later the course was altered 
to 230°T in order to leave still more room for the 
intended starboard-to-starboard passing. At 1812 
a fog signal was heard from the approaching 
vessel, and the pilot stopped the engine. The 


SCIENCE AND THE SEA 


Too much speed during periods of too little visibility is often the cause of collision. 


radar indicated that the approaching vessel was 

still off the starboard bow and heading toward a 
Two Bush Ledge Lighted Gong Buoy at approxi- 
mately eight or nine knots. At 1814, observing 
that the bearing continued to increase, Ship A 
again went ahead at half speed still sounding fog 
signals. 

At 1816 the radar indicated that the relative 
bearing ceased to open, and, again, the engine 
was stopped. Visibility at this time was restricted 
to such an extent that personnel in the wheelhouse 
could not see beyond the ship’s bow. Fog signals 
were alternately exchanged between the two 
vessels as they steadily approached their rendez- 
vous with fate. 

The master ordered emergency full astern and 
sounded the appropriate signal when, at 1819, three 
short blasts were heard at close range from the 
ship ahead. The following moments were filled 
with anxiety as all eyes strained to pierce the mist 
ahead. At 1821 a slight jar was felt, and it was 
determined that Ship A had collided with Ship B 
almost perpendicular to its port side. 


SHIP B Closeup of impact area 


COLLISIONS—1969 


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Ship B was proceeding through the Gulf of 
Maine on the last leg of a voyage from Newport 
News, Virginia, to Searsport, Maine. With the 
master at the conn, the vessel made a normal 
approach to Penobscot Bay, westward of Monhe- 
gan Island, and continued toward Two Bush 
Channel on a course of 045°T at a maneuvering 


81 


speed of approximately 9 knots. At 1646 hours 
the vessel was abeam of Monhegan Island and 
approximately 2 miles westward. At this point 
the vessel began to encounter patches of fog, and 
the master commenced sounding fog signals. 

The passage continued toward Two Bush 
Channel, the navigation now being accomplished 


SCIENCE AND THE SEA 


entirely by radar and by use of the fathometer. 
All fixes obtained were the result of radar ranges 
and bearings. At 1719 the vessel was fixed abeam 
of Burnt Island Lookout Tower at a distance off 
of approximately 3,500 yards. The vessel continued 
ahead at maneuvering speed. 

After passing the Burnt Island landmark the 
fog became more dense over larger areas. At 1741 
the vessel was abeam of Marshall Point Lighted 
Whistle Buoy / at a distance off of approximately 
800 yards. At 1804, when almost abeam of Tenants 
Harbor Lighted Bell Buoy 1, the master altered 
the ship’s course to 079°T so as to enter Two 
Bush Channel. 

At 1811 the radar revealed a target ahead 
which the master initially evaluated as being a 
large ship at anchor in the lower reaches of West 
Penobscot Bay. He thereupon reduced the engine 
speed to half-ahead and a minute later further 
reduced engine speed to slow-ahead. At 1814 the 
master heard the fog signal of an approaching 
vessel. Finally realizing that the ship observed 
on radar was in fact underway, he stopped the 
engines. At this time the two vessels were about 
114% miles apart. 

Closely watching the other ship’s movements 
on the radar screen Ship B’s master automatically 
decided on a port-to-port passing and attempted 
to shape his course accordingly. Observing that 
the downbound ship bore steadily to the right, he 
made rapid, successive course changes to the right 
finally steadying on 145°T. At 1818, aware of the 
proximity of the approaching vessel and that his 
ship was headed toward shoal water, the master 
ordered full astern and sounded three short blasts 
on the ship’s whistle. Shortly thereafter three 
short blasts were heard from the approaching 
vessel at close range. 

At 1820 the bow of Ship A was visually 
observed as it loomed out of the mist about 100 
yards to port. Convinced that a collision was now 
imminent, the master ordered full ahead and full 
left rudder in an attempt to lessen the impact. At 
1821 the bow of Ship A struck Ship B, cutting 
deeply into the port side of number 2 hold. 


ANALYSIS 


The primary cause of this casualty was simply 
that both ships were operated without due caution 
and at immoderate speeds in restricted waters 
during a period of extremely low visibility. Each 
ship was in Inland Waters and was, therefore, 
bound by Article 16 of the Inland Rules. Neither 
ship, however, could be said to have been fulfilling 


82 


the intent and purpose of that article. 

Ship A detected Ship B by radar approxi- 
mately 30 minutes before the unfortunate encoun- 
ter, but no change in speed was effected as a result. 
Upon hearing the fog signals of Ship B nine 
minutes before the casualty, Ship A stopped her 
engine in accordance with accepted practice and 
Article 16. Two minutes later, Ship A went half- 
speed on her engine. This action was taken just 
seven minutes and approximately 1 mile from the 
scene of the collision, at a time when some drastic 
collision avoidance action was obviously necessary. 
True, it had been determined by radar that 
Ship B’s bearing was opening progressively to the 
right. However, Recommendation 3 in the Annex 
to the International Rules, Recommendations on 
the Use of Radar Information as an aid to avoiding 
Collisions at Sea, which, it would seem, are 
applicable to the use of radar in any circumstance, 
states, When navigating in restricted visibility, the 
radar range and bearing alone do not constitute 
ascertainment of the position of the other vessel 
under Rule 16(b) sufficiently to relieve a vessel of 
the duty to stop her engines and navigate with 
caution when a fog signal is heard forward of the 
beam. 

Even after Ship B’s bearing ceased to open, 
five minutes and less than a mile before the fateful 
meeting, the only action taken by Ship A was to 
stop her engine. Ship A’s emergency full astern 
order 2 minutes before the collision was given too 
late to counter the way of a large ship. 

Ship B encountered dense fog shortly after 
entering inland waters yet continued toward the 
narrow waters of Two Bush Channel with no 
reduction in speed. Ten minutes before reaching 
the collision site, Ship B’s engine speed was 
reduced and a few minutes later stopped when it 
was realized that Ship A was underway. No 
radar plot was maintained on Ship B, a device 
which might have revealed Ship A’s intentions in 
time to prevent Ship B’s radical course changes 
to the right. As in the case of Ship A, Ship B did 
not attempt to negate the way until too late. 

Ship A’s decision to attempt the unconven- 
tional starboard-to-starboard passing during a 
period of poor visibility and without a passing 
agreement was an exercise in poor judgement. 

Finally, both ships violated Article 18, Rule IX, 
in sounding the three blast whistle signals to 
indicate full astern, for neither vessel was in sight 
of the other at the time. 


COLLISIONS—1969 


CONCLUSION 


The majority of mariners will undoubtedly 
agree that the risk of collision increases with speed 
and reduction of range; that close-quarter situa- 
tions are dangerous and at high speed, an invitation 
to disaster; and that all of these risks are com- 
pounded by factors which tend to limit visibility 
and the sources of information. Well acquainted 
as they are with these truisms, mariners continue 
to be plagued by a high incidence of collision that, 
annually, accounts for serious loss of life and 
costly property damage. 

Other than the Rules of the Road, there is no 
panacea for the prevention of collisions. Even the 
Rules, although meticulously forged to cover every 
possible situation, will not prove effective if they 
are carelessly applied or wilfully ignored. Fortu- 
nately, all Rule violations don’t necessarily result 
in collision, but very few instances have been 
recorded in which a collision was not. the result of 
some Rule violation. Obviously, successful collision 
avoidance depends, in no small way, upon a strict 
adherence to the Rules of the Road by all parties 
concerned. 

In the foregoing cases the prevalent cause of 
each collision was the violation of Rule 16 (Article 
16 of the Inland Rules in Case 4). This rule is, to 
an extent, an interpretive one in that it permits 
the shiphandler a certain latitude in determining 
speed and/or disengaging maneuvers. To prevent 
possible misinterpretations, however, the Inter- 
national Rules of the Road include an Annex to 
the Rules which helps to explain the somewhat 
vague phrasing of Rule 16 for radar-equipped 
vessels. 


Under Rule 16(a), for example, a ship in 
restricted visibility shall go at a moderate speed 
and have careful regard to the existing circum- 
stances and conditions. The precise value of what 
constitutes moderate speed is not given for the 
simple reason that it will vary with the situation. 
Paragraph 2 of the forementioned Annex to the 
Rules states that Rule 16(a) applies to radar- 
equipped vessels and further indicates that the 
vessels so equipped use their radar information in 
determining moderate speed. It is only reasonable 
to expect, therefore, that personnel of radar- 
equipped ships would interpret the meaning of the 
word moderate in a somewhat different sense 
than those in a ship without radar. In the final 
analysis, the same responsibilities exist, and it 
must be borne in mind that any speed which con- 
tributes to a collision will be deemed immoderate 
by the courts. 


83 


According to the Annex, radar-equipped 
ships are not exempt from the requirements of 
Rule 16(b) simply because they hold radar contact 
with the vessel under advisement. All ships must 
stop their engines and navigate with caution until 
danger of collision is over. Radar or not, this is 
sound advice, for in most cases when a fast moving 
ship hears the fog signal of another, she is probably 
already too close for safety. 

Rule 16(c) permits and encourages ships to 
take early and substantial action to avoid a close- 
quarters situation when they detect the presence 
of another vessel forward of the beam. Detection, 
in this rule, obviously means radar detection, and 
radar navigators should pay particular attention 
to the alternatives offered. The determination of 
when is early and what is substantial rests with 
the mariner and depends upon the circumstances 
of the case. Certainly, any action taken by either 
of two ships with a relative closing speed of 36 
knots (as in Case 1) should occur before they are 
only seven or eight miles apart. On the other hand, 
a small change of course, even at considerable 
range, is not to be considered as substantial action. 

The point in Rule 16(c) that seems to have 
been missed by all of the ships is that if a close- 
quarters situation cannot be avoided by early 
action the vessel shall stop her engines in proper 
time to avoid collision and then navigate with 
caution until danger of collision is over. 

There is nothing in either the Rules or its 
Annex, of course, which can regulate the efficiency 
with which radar is used. This is a matter of 
individual proficiency, the same as being a good 
or poor helmsman. There is little excuse for a 
mariner obtaining an incorrect value of bearing 
and distance by radar observation, whether it be a 
true-motion or relative-motion observation. Such 
inept usage of radar can lead him down the 
primrose path and place him in a position where 
good fortune, rather than skill, becomes the prime 
factor in whether or not a collision will occur. 
Skillful interpretation of the radar picture and a 
full appreciation of the developing situation are 
essential if behavior is to be based on the use of 
radar. 

It is well known that the maintenance of a 
graphic plot is essential to intelligent radar usage. 
Without assistance, however, a watch officer of a 
merchant ship may be unable to plot, contacts 
continually due to the pressure of other duties. 
In this case a simple timed record of ranges, 
bearings, and course changes should be kept. But 
if the risk of collision truly exists, a watch officer 


SCIENCE AND THE SEA 


needs the data provided by a plot, and he should 
not hesitate to call for qualified assistance on the 
bridge. 

International Rule 27 (and its companion 


Article 27 under Inland Rules) when judiciously 
applied is indeed a General Prudential Rule when 
the situation becomes tight. 


U. S. GOVERNMENT PRINTING OFFICE: 1969 O - 356-697 


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