Review Notes for Deck Officers - Padilla

M I L L E N N I UEMD I T I O N

NOTIIS ITHITIB$T F0n

DIIOKOFFICDIIS by

Arcenio G. Padilla Jr.

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IT{ARITIME CONSULTAI\ICY FORDECKANDENGINEOMCERS

Sth FloorA.msirBldg.,P. Paredescor. S. H. L.oyolaSts.,Sampaloc,Manila Tel. Nos. 733-1243. 736-5949. 736-5952 E-rnailaddress:[email protected]

PhilippineCopyright@ 1994 by ArsenioC. Padilb Jr' is prohibitedwithout All rights reserved. Reproduction or use of editorial or pictorial contentin any manner contained the information use of the to with respect "ipr"ri permissionin wriiing. No patentliability is assumed responsibitty no publisber assumes the book, this preparation of in the taken has been herein. While every prccaution tbe use of the information for errors or omissions. Neither is any liability assumedfor danages resulting from containedherein EDIT|On-- JANUARY2000 REVISED

rsBN 971-91521-0-9

I'rinted by: One Way Multi-Media Center 2203 Tafl Avenue Manila, PhiliPPines

PREFACE This bookwaspreparedto assistDeckOfficen by showingthem the multiple choicetypeof Examination they may encounterin the LicensureExamination.All the answersto the questionsare basedon studyand research. The solutionsto the problemswere simplified for easierunderstanding.Formulasfor Navigation were includedfor quick reference. and Seamanship Candidatefor LicensureExaminationshouldreadthis bookand studythecontentstloroughly. This will enablehim to gain confidenceduring the examination.

I would like to expressmy gratitudeto Capt. RomeoResultan,to Chief Mate RenatoSangalang, Chief Mate NelsonPrias,LCdr. Angelo Tagle,Chief Mate EdgarMartinez,the staff of Collegeof Marine (PMMA), to PMMA Librarian Ltjg. Delia Mailed for their wholeheartedsupport. Transporcation Specialthanksare owed to the following ReviewCenters- GoldenSuccess,Achievers,RomeoB. Resultan,Seafarersof the Philippines,Seacraft,and D' Navigators. I want to give specialthanksto Third Mate RamiroBellezafor his artisticdesignof the cover. And last,but not least,to my wife Angelitaand threechildrenAngelica,AndreaFe and ArsenioIII remarkablepatienceandunderstanding who demonstrated right up to the end.

ARSEMOC.PADTTLAJR. ReviewInslructor FormerAssistantProfessor PhilippineMerchantMarine Academy

iii

" Success,s the product of determination,couraga,and hardwork. " A C Padilla Jr.

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TABLE OF GO}ITEilTS L

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TIDES AI.IDCURRENTS WEATTIERELEMENTS ELECTROMCNAV[GATION................. MARINET.AWSAND SHIPBUSINESS.... MARINEINSIJRANCE SIGNALINGAND COMMUMCATIONS .............. COLLTSToNREGLJLATTONS CHARTSAND PUBLICATTONS AND MAGNETTSM .......... COMPASS PILOTINGANDSAILINGS NAUTICALASTRONOMY CELESTIALNAVIGATION NAVIGATIONPROBLEMS A B. C. D. E. F. G. H. I. J. K. L. M. N. O. P. a. R. S. T U. V. W. X. Y. Z. AA

Page 1 .............23 ..........59 .......87 107 .............. .......I2I ...........131 ..................... 161 ...........r71 .......181 ........199 .........279

MercatorChart Construction........... .................:.. ....229 Visibilityof Lights..... .......231 Deviation Compass ...........233 Deviationby Azinuth Compass ............236 DeviationbyAmplitude................. ............237 Compass RightPlaneTriangle........... ...................239 Distance by VerticalAng1e.......... ..........240 .........241 ObliquePlaneTriang1e................. .................242 Couneto Intercepta Vessel BearingProblems .............243 BearingsandDistance Otr.............. ......250 PlaneSailing .....................252 Mercator ...............254 Sailing........;........... ParallelSailing .................255 Middlelatitude Sailing.. .......................259 Traverse .......................260 Sai1ing.............. ..........262 GreatCircleSailing Sailing ............268 Composite ................. .....................270 CurrentSailinC ..........271 SetandDrift ........... TrueandApparentWind ....273 Time Problems .......................276 .............. ......280 GeographicalPosition ...................281 TimeDiagram Bquationof Time....... ........283 .......................284 OrthographicProjection Triangle. .......................287 RightSpherical

BB. CC. DD. m. FF. ClG. IlH. )CV. xv. X\{. XVII. )Ofltr. )O(. )O(. )O(I. )oil. )Oiltr.

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Triangle ObligueSpherical Correctionof Altitudes. lnterceptMethod MeridianAltitude....... Error ........... Chronometer Other Problems SpeedbyRevolutionsandFuel Conservation

SAFETYOFUFEAf,SEA .............. SHIPHANDLING SHIPCONSTRUCTION CARGOGEARS CARGOHANDLINGANDSTOV/AGB CARGOASSESSMENTS STABILITYANDTRIM.......... ................. STABILITYANDTRIMCALCULATIONS AREASANDVOLUMES ADDENDIJM A Meteorology B. MarinelawsandShipBusiness C. Navigation.. D. Seamanship................ ANSWERS A TidesandCurrents................. B. WeatherElements C. ElectronicNavigation D. MarinelawsandShipBusiness E. Marinelnsurance............. andCommunications E Signaling G. CollisionRegulations H. ChartsandPublications.............. I. Compass andMagnetism............... J. PilotingandSailings K. NauticalAstronmry L. CelestialNavigation M. NavigationProblems N. Safetyof Life at Sea.............. O. ShipHarrdlinC................. ........... P. ShipConstruction .......... Q. CargoCrears .............. R. CargotlandlingandStowage S. CargoAssessmencs T TrimandStability U. Mensuration............. COMMONCoIIVERSIONFACTORS

Thbleof Contents

Page ....................296 ....300 ..............301 .......302 ....................303 ................305 ............306 ..........313 ........335 .......,..,,.343 .....353 ..,.......363 ...,..,,...379 .,..387 ........401 .......,...419 ....423 ...............431 ......436 ..........441

...................461 ................462 ..........463 ...............466 .....466 ................467 ..........467 ..............468 ...........468 ............469 .............470 .............471 ............471 ...................473 ......474 .....474 ...............47 5 ......475 ..............476 .................476 ............476 ...........477

TIDES fide is the rise and fall of water.

Atlantic coastof the U.S. are of this type.

fidal Grrrent or fidal Stream is the periodic horizontal movementof the water.

Dlurnal Tlde. Only a single high and single low water occnr eachtidal My Ex Gulf of Mexico (N. slnre), Java Sea,Gulf of To*in.

Ildd Phemmenon is the periodic motion of the watersof tbe seadue to differencesin the attractive fores of various celestid bodies, principally the moonandthe sun,upondifferentpartsof therotating earth. Iltgh Ttde or Hlgh Water is the maximum height reacied by tide. Low THc orlow Water is the minimum level to which the tide falls.

Mlxed fide. Characterizrlby alarge inequality in the high waterheights,low waterheigbtsor in both. Ex. Pacific cotnt of thc A.S. Sprlng Tldes. Tideswith higher high andlower low. Occurat timesof new and full noon ( sunandmoon arein conjrmctionand at oppositionwith the earth). Neap lldes. Tides wifr lower high and higher lor. Occur at times of fnst and third quarters(sun and moon are in quadraturewith the earth).

The rate of rise and fall is not unifomr. From low water,the tide beginsto rise slowly at first but at $olar THe" High and low watersoccuf at aboutthe an increasingrate until it is about halfray to IIW. sametime each day due to the effect of Oe sun. The rate of rise then decreasesuntil HW is reached Examples are tlu areasof S.PaciJicand Indoncsia. and the rise ceases. The falling tide bebavesin a Ihuble Low Water (as at Hoek Van Holland) and simihr manner. Double Hlgh Water (asat Southanpton,England). Stand is the period at tIW or LW during which At suchplacesthere is often a slight fall or rise in there is no sensiblechangeof level of tide. the middle of the high and low water period. The praaical effect is to crcatea longer period of stand Rangeis thedifferenoein height betweenconsecutire at high or low tide. high and low waters. PcrtgeanTlde. Occus whenthemoon is atthepoint Ildghtof fide is the vertical distince fron the chart in its orbit nearestthe earth. The lunar semidiurnal soundingdatumto the water surfaceat any stageof rangeis increased. the tide. Apogcan llde. Occun wbn the moon is farthest RIse of,Tlde is the vertical distancefrom the chart from Oeearth. The semidiurnalrangeis decreased. soundingdatum to a high water dafim. Iboplc llde. Occurs when the moon is at its maximrrmsemi-monthlydeclinationN or S. Diurnal TYPES OF TIDE effect is at a maximnm. Semldlurnal Tlde. There are two high and two los' waterseachtidal daywith relatively small inequality Equatorlel IHc. Oocurs when the moon crosses in Oe high and low water heights. Tides on the the equator. Diurnal effctis rninimum.

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NEAPTIDESOCCURATTIMESOF lsrAND S m Q U A R T E R SR.A N G E o F T I D E I S L E S S THANAVERAGE.

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Tidesand Currents

LOWWATER

METEOROLOGICALEFFECTS

TIDAL CYCLES Lunar Day. Vl hoursand 50 minutes. Synodlcal or Lunar Month. The moon revolves aroundthe earth with respectto the sun. About 29 Vzdays. Tbopical Month. 27 th days. The effect of the m@n's declination is repeatedin Vzof a Tropical Month. Anorralfstic Month. 27 Vz days. The cycle involving the moon'sdistancerequiresan Anomalistic Month. Nodal Period. 18.6or 19 pars. An importantlunar cycle. Luniddal Interval. The interval betweenthemoon's meridian transit and a particular phaseof tide.

1. Onshore winds raise the level of the sea and offshorewinds lower iL 2. During periodsof low annosphericpressure,the water level 0ends0obe higher than nomral.

TIDAL CURRENTS Rotary Clrrreni It flovs continuously, with the directionschangingthroughall pointsof thecompass during the tidal period.The cycleis completedin 12 houn and 25 minutes. Reverslng Current. Flows alternately in approximatelyoppositedirections with an instant or short period of slackwater. Prevalentin rivers or straits or where the direction of flow is more or less resficted to certain channels.

Ilydraullc Current. Generatedlargely by the changingdifferencein height of water continuously fidal Datum. Alevel fromwhichheightsanddepths at the two ends.The tides at the two endsof a strait are measured. are seldomin phaseor equal in range. Mean Low Waten The averageheight of all low Bore. The advanceof the low water trough is so watersat a place. much retarded that the crest of the rising tide Mean SeaLevel. The averageheight of the surface overtakesthe low, and advancesupstream as a of the seafor all stagesof the tide over a l9-year churning, foaming wall of water. period. Used in Baltic Sea(tideless)aschart da- Frldy. A quasi-circular movementof water whose tum. areais relatively small in comparisonto the current Ilalf-fide Level. The level midway betweenmean high water and mean low water. Mean High Waten The averageheight of all high watersover a l9-year period. Heights of land featuresare usuallyreferredon nautical charc w a high water daturn The level usedon charts of the U.S. and terrilories. The depth of water available at anytime is ob tainedby adding the height of the tide at the time in questionto the charteddepth, or by subracting the predictedheight if it is negative.

with which it is associated . fide Rips. Small waves formed on the surface of waterby meetingof opposingtidal currentsor by a tidal current crossingan irregular boftom. Flood. The movementof water toward the shoreor upstream. Ebb. The movementof water away from shoreor docrnstream. Set is the direction toward which the current flows. Drtft is the speedor velocity of the current.

Tidesand Cuments

OCEANCURRENTS Ocan Cumt A welldefined curcnt extending orcr a considcrable regim of the o pan.

Cablis forc is gncakr h higlur latitudei atd is nnre cfrcaive in deepwater.

Ferlodlc ftncnt The speedordirtction of vfiich c,hangescplicntly u regular inbrvals, as a tidal current.

The difference between wind directim and surfre wind-ctrrent directim variesfrromabout 15 deg. along shallow msal arcasto a maximum of 45 &g. in the deepooeans.

ScrsmtCurncnts. Has largechangesin s@ diroctim due to seasmalwinds.

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Pcrmmnt Cur.mi One whicb exocrienoesrelatively li[le periodic c seasmalc,hange. Corstrl 6rrat. Flowsrougbly paratlel to a otnlit, mtside tbe surf zone. Logrhore QrcnL One parallel o a'sbore,insirb tbe surf zme. Gener-arcd by warresstriking thebeach at my angle. OffshoneGrrcot. the shore.

Any current somedisance ftrm

IBhc€ Currcn.

Any cunent clce to tbe shorc.

Strc.m Cuncnt moving current.

A relatirrcly nanrow,deep,fast-

IHfl Curcnt. currenL

The speoddcurrent d€pendsupontbe the speed of the win4 its @nstancy,the length d time it,bas bloum"erc.

CURRENTS RELATED TO DENSITY DITTERENCES In an area of high density, the waEr snrhoe is bn er then in an areaof lon, &nsity. Waterteods'to flow Aon an area of higher water (low demity) to oneof lower water(high density).but &re to rotati@ of t[e eartb, it is being deflectodbwad the nglr in the N. lbmirybere, and toward the lefr in tbe S Ihispberc. Tbe grearertbe density gradient (rare of ciange with disance), the faster ttre related qrrenL

A br@$ shdloq slow-moving

MAIN CURRENTS OF THE OCEANS

CAUSES OF OCEAN CUR,RENTS 1. Wind 2. Densitydifiercnes in thewater 3. Depthofwarcr 4. Underwater topography 5. Sbapeof thebasinin whichtbeqrnentisnnning 6. Ext€ntandlocuimof land 7. Deflectimby therotatio of tbeearth. Tbestressof windhwing &rosstheseecurses tbesurft€laycrof warc(bmw. Thismotim is transmittcdto eacb suooeedinglayer below the sufia, but&ptointemel ftictim within thewatcr, ttv ratcof motiondecnasswith&pth

Nfith EquetorlelCurcnr Florvswtstwardin the general arpaofNE trades. Somh Equeea|e| Currcnt. Fhrys c/estwardin tbe generalareaofSE trades. Esrtorlrl C.rnntorcurrent. Sels iowdd the east in the generalvicinity of the doldrums.It reachesa maximrrmduing July and August and minimrm in DEcemberand January. Gdf Strr.n. The most remartable of all ocean cur€ots. 13fcillws gmelly along tbe east@Gt d N. America, fhuing arormdnffidC northmrd and tben northeastwtrd bwad Cspe llilteras. Gulf Strem isawatm ctrrcnl

A wind-driven currcnt is being deflcctcdby qxlus rcrce drc b therotrtiqt of thecarth. The Lrbnfu Cuncd. Originating frm old arctic dcflectio is ffiNardt}r,,rightin thc N. IDnisphcre mtcr f,owhg suthca*umd. Canics laAe quentiand oward thc lcft in thc S. Ikmbphcrc. Tbc tiesof ie.

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NorthAtbntlc Current. A vast slow-movingcurrunt in the generd vicinity of the prevailing westerlies. Brazll Crnent. Flcn's southwestwa"dalong the Brazilian coast. SouthAtlandc Cun ent. A broad,slow-movingcurrent in the generalvicinity of the prevailing westerlies. Benguela Current. A strongcurrent flowing northward 0ofollow the west coastof Africa

mania. Peru Curnent or Humboldt Chrrcnt. A narrow, fairly sable oceancurent that flows no'rthwardclme to the S. American [email protected] originatesoffthe oast of Chile at aboutLar 40S and flows past Penrand Ecuador0othe southwestextremity of Colombia. Rcsel Current. A weak northern branch of the S. Equatorial Current flowing toward the west and northwestalong both the southernand northeastem coastof New Guinea

Monsmn Cument. Flows eastwardand southeastAgulhas Currrcnt. A generally southwestward- ward acrossthe Arabian Seaand the Bay of Bengal. flowing ocean culent of the Indian Ocean,flon's Wcst Australla Culr.ent. An Indian OceanCuralong the eastcoastof South Africa rent whicb generallyfirst flows northwardand then Kuroshlo (Japan C\urmt). Carries large quanti- northwestwardoff the west coastof Australia. ties of warm tropical water to higher latitudes and then curves toward the east 6 a major part of the Wcst Wlnd Drtft. An o@anqurent that flows eastgeneralclockwisecirculation in the N. Hemisphere. ward through all the o@ansaround the Antarctic continent. Callfomla Grrrent. A N. Prcific Ocean curent flowing southeastwardalong the west coast d N. Wcst Greenland Cument. An oceancurrent flowAmerica ftom west of Vancouverto the westof Bqia ing northward along the west ooantof Greenlan4 into the Davis Strait. Califomia. Davldson Curent. A weakcountercurrentflowing northwestwardalong the west coast of N. America from Southem California to VancouverIslan( inshore of the southeasterlyflowing California Current.

East Greenland Culrent. An oceancurrent flosring southwardalong the east coast of Greenland. carrying water of low salinity and low temperanrre.

Eest Austrelle Currnent.A S. Pacific OceanCurre.ntflowing southwardalong the eastooastof Australia ftom the Coral Seato a point northeastof Tas-

Ect Slbertan Coostol Cuncnt. An cean curent in the Chukcbi Seawhicbfriins the northwardflowing Bering Currentnorth of EastCape.

Canary Cunent. The southembranchof N. Atlantic Current (which divides on the easternsideof the Oyashlo. Formedby cold water flowing southward oean). It moves south past Spain and southwestthrough the westernpart of Bering strait between ward along the NW coastof Africa and pastthe CaAlaska and Siberia and joined by water circulating nary Islands. counterclockwisein the Bering Sea It brings quanFalkland Current. Originating mainly from the tities of seaice but no icebergs. CapeHom Current in the north part of Drake PasAlaska Current. The northern branch of the Aleu- sage.It flows northwardbetweenthe continent and tian Current orving in a counterclockwisedirec- theFalkland Islandsafter passingthrough the strait. tion. generally follows the ooast of Canada and East Afrlca Costal Clrrrent. An Indian Ocean Alaska. Current which originat€s mainly from that part of Aleutbn Current. An easnvardflowing N. Pacific the Indian South Equatorial Current which turns OoeanCurrent which lies north of the N. Pacific northward off the NE oast of Africa in the vicinity of Lat 10" S (Somali Current). OceanCurrent.

6

Tidesand Currents

OCEANWAVES YYevesare undulationsofthe surfaceof the water.

Gnoup Veloctty. The speedat which the wave system advances.

CAUSES OF WAVES:

Oscllllatory Wave. A wave in which only the fomr advances,the individual particles of the medium moving in clmed orbits, as ocean waves in deep water.

l. 2. 3. 4.

Wind Submarineearthquakes Volcaniceruptions Tides

Ripples. Small waveletscausedby abreezn of less than 2 knots starting to blow acrosssmoothwater. Disappearrapidly as the breezedies. Gravity \ilaves. More stableand gradually form if the wind speedexceeds2 knos. They progresswith the wind. Swell. A relativelylong wind wave,or seriesof waves that has travelled out of the generatingarea.Waves that continue on without relation to local winds.

Wave of Tianslatlon. A wave in which the individual particlesof the medium are shifted in the direction of wave travel, as oceanwavessin shoal watars.

EFFECT OF CURRENT.ON WAVES A following current increaseswavelengthand decreaseswaveheight. An opposingcurrent decreaseswavelength and increaseswave height.

Sea.Wavesgeneratedor sustainedbywinds within their fetch.

WAVESAND SHALLOW WATER WAVES CHARACTERISTICS Oceanwavesare very nearly in the shapeof an invertedcycloid, the figure formed by a point inside the rim of a wheel rolling along a level surface. Crests.The highestpartsof waves. Thoughs.The inte,rveninglowest parts of waves. Wave IIeighL The vertical distancebetweentrough and crest.

When a wave encountersshallow water, the movementof the individual particles of water is restrictedby the bottom, resulting in reducedwave speed.The shallowerthe waterthe slowerthewave speed.As the wavespeedslows,the period remains the sameso the wavelengthbecomesshorter.Since the energy in the waves remains the same, the shorteningof wavelengthsresults in increased heights.

Tsrnamis are ocean waves produced by sudden, Wave Leng$. The horizonal distance between large-scalemotion of a portion of the oceanfloor or crests,measur€din the direction of travel. the shore, as by volcanic eruption, earthquakeor successive seaquakeor landslide. Wave Pcriod. The time interval betweenpassage Selsmlc Sea Waves. Caused bv submarine of successivecrestsat a stationarypoint. earthquake. Waveheight,lengthandperioddependon wind speed,the length of time it hasblown and its fetch. Epicenter. The point dircctly abovethe disturbance, at which the wavesoriginate. Fetch. The straight distanceqlsvshnstravelledov€r the surface.The disance wave has travelled from fidal Wave. Either a tsunami or a stonn tide that overflowsthe land. formation 0odecay.

Tldesand Cunents

7

Tlunrmis.arcoeriesofwavcs.In deepwater,th wavebeigbt of a tsunarniis rever greatertban 2 or 3 fer Since the wavelcngth is rsually onsideraHy pqp thsn 100mites, thewan is not conspicttousat sc& Storm Ttdcs c Storm Surges or Ttdel Wrvcs. Cmsist of a single wave'crestand baveno period or uaveleng0. Three efiects ln r stmlndua

r rbc ln scehvcl.

3. The lonr atmosphericpressnrethat mompanies severestonon catnes t[e "inverted barmeter". An inch of menry is equivalent to about 13.6 incles of water and the adjusment of the sea surfroe to the reducedpressurecan amormt to severalfeet at equilibdum. Oil hasprorad efrectivein modifying the effects of breaking wavqs,and bas proved useful to vessel at sea.Its €fict is greatestin &ep nater, where a srnrll quantitysffces if thecrilcanbemadeto spread to windu/ard.In shallow uat€r wherethe wabr is in motion over the bottom, oil is lesseffective.

1. Wind stresson tbe seasurftce which results in piling-up of water. The heaviestoil, notably animal and vegeable 2. Tbe covergencedwinddriven currelts, which elewrcs the sea surfrce along the oonvergence oils, are the mct effective. line.

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Tldcsand Cuncnts

TIDES A]ID CURRENTS 1. In certain areasof the S. Padfib, tidesoaur almosi at the sametime eac,hday due to th influene by the: a. Sun c. Planetsin onjrmction D. Moon d. Regressionoftbenodes 2. T\e amount that a crrrent travels in one hour is termed as: a. Set ,. Ftood c. Drift

d. Ebb

3. Tides having higher lows and lower highs occur when: a, T\e moon is at its marimrrm north declination D. The sun and the mmn are in conjunction c. The sun and the moo are in oppoaition d. Tfu moon is at first and last quarter 4. When two conseqrtivehigh or low watersare d large differencein heights,tbey are called: a. Diurnal tides c. Mixed tides D. Semidiund tides Tropic tides 5. When there are small difrerene betweenthe heights of two suc@ssivehigh or low tides, tbey are called: b. Senidiurnal c. Solar 4. Diurnal d. Mixd 6. A tide is called diurnal when: a. Only ore high and one low wat€r ocors in a hmar day D. me high tide is higher and low tide is lower tban normal c. The high tide and low tide are six burs apart d. Two high tides ccur duing a luar day 7. Tropic tides arc causedby a. Itfioonbeing at its maxim,m doclination North or South D. lfioon crossing the equator c. Sun andmom arc in line d. Sun and moo ar€ at quadraturewit[ tbe earth 8. Neaptides q the 6des that bavelmrer higbs and higber lows occur when the noon is at: c. Qtadrature with tbe eart[ and sun a. Oppoeitfunwith tbe earth and sun \ d. |+pge, D. Cmjunctim with the earth and sun 9. Spring tirbs a tides that have higber highs and locrer bws ocor when tbe moon is at a. Oppoeitionor in mjunctim with the earth and sun D. Quadraturcwith tbe earth and sun c. Apogoe d. Perige 10. Mean low water is cmroctly delined as the averageheigbt d c. all lon, wateG a. tb two daily bw tides d. tbbwerlowtidcs D.6ehigbrndlowtides

frdesand Currents

11. Althougb, tide ables list the times and heightsof tides at a speciftclocale, thesecm be alteredby: I. onshorewinds tending to rise the level of tides tr. bw atmosphericpr€ssurecausingtides o be higher than normal D. tr only c. both I and tr d. neither I nor II a. I only 12. T\e diurnal inequality of tides is causedby: a. the moon being at perigee b. the declination of the mmn

c. changingweatheronditions d. themoon being at apo3iee

13. In cenain areasof the worl4 there is often a slight fall of tide during the middle of the high water period. The practical effect is to createa longer period of standat high water.This specialfeature is called: c. apogeantide d. bore c. doublehigh water D. perigeantide 14. When a strong curcnt sets ove,ran irregular bosom, or moetsan opposing qxrent, which of the following mayoocur? D. bore c. etrbcurrent d. slack water a. tide rips 15. The period at high or low wat€r during which there is no changein the height of the water is called: c. standof the tide d. revening of tide 4. rangeof the tide b. planeof the tide 16. "Standof the tide" is that time when: a. the vertical rise or tall of the tide has stopped D. slack watersoccur c. tidal current is at ma:rimum d. the actual depth of water equalsthe charteddepth 17. What doesthe term 'tide" refer to? a. horizontalmovementofthewater D. verticalmovementofthewater

c. mixing tendencyofthewater d. salinitycontentofthewat€r

18. The rangeof tide is the: a. distancethe tide movesout from the shore b. duration of time betweenhigh and low tide c. differencebetweenthe heights of high and low tides d, maximum depthof the water at high tide 19. Itrowmany high watersusually occur eachday on the East coast of the united states? d. fow c. three b. nvo c. one 20. Currentsrefer to the: a. verticalmovementofthewater D. horizontalmovementofthewater

c. densitychangesinthewater d. noneoftheabove

21. T:heset of the curent is the: a. speedof the current at a particular time !. 6p1i6rrm speedof the current

c. direction ftom which the current flows d. direction to which the current flows

22. Setof the current is: a. iB velocity in knots D. directionfromwhereitflo$/s

c. estimatedcurent d. directiontowardswhereitflon's

10

Tldesand Currents

23. Which of the following describesan ebbcurrent? a. horizonal mo\'€mentof water awayftom the land following low tide D. horizontal morrementof waEr towards the land following low tide c. horizontal movementof water away ftom land following high tide d. horizontal movementof wabr towardsthe land following high tide U. The movementof water away ftom shoreor downstreamis called what type of cunent? d. slack c. flood D. €bb c. revening 25. Slackwarer occunrwnen Oerei: a. nohorizontalmotionofthefater D. no vertical motion of the water

c. aweakebborflmdcurrent d. neitber a vertical nor a horizontal motion

2f.. The velocity of a rotary tidal current will increasewhen the moon is: c. atperigee D. fuU a. new

d. alloftheabo,e

27. Ttre referencedatu4 usedin determining the heigbts of land featureson most charts is: d. meanlow water c. meansealevel a. meanhigh water D. half-tide level 28. The shorelineshown on nautical chars of waterssubjecto large tidal fluctuationsis usually the line of mean: d. tidelevel c. bnrwater D. highwater c. lowerlowwater 29. Which of the following statementsregardingcurents idare correct? I. In general,the s@ of tidal currents are lessalong straight coaststhan indentedooasts. tr. StrongersetsDward or awayftom the shorecan be expeaedwhen passinga straight omst than an indentedone. d. neither I nor II c. botb I and tr D. tr only a. I only 30. Regardingtides and currents,which of the following iJare correct? I. The time of slack water doesnot generallycoincide with the time of high or low water. tr. The time of maximum velocity d the current doesnot wually coincidewith the time of the most rapid changein the vertical height of the tide. d. neitherlnorll c. bothlandtr D. tronly a. Ionly 31. The vertical distanoebernreentrough and crestof a wave is called: c. range D. magni$de a. rise

d. heigbt

32. Prining of the tide occu$: c. at,timesofnewandftrllmmn D. betweennew and fust quarter

c. betweenfirstquarterandfullmmn d. betweenthird quarter and new mmn

33. Iaggrng of the tide occur''s: a. betweenfust quarter and frrll noon D. betweennew and first quarter

c. betweenfull moon and third quarter d. noon and earth are at quadrature

34. An important lunarcycle affecting the tidal cycle is called the nodal period. How long is this cycle? d. 18 months c. 6 years D. 19 yers a. 16 days '

35. The averageheight of the snrftcc of the seat'or all st4gesof the tide over the 19 yearperiod is called: d. 'half-tide level c. rncansealewl D. meanhigh water 4. rneanlow water

Ttdesand Cunents

1t

36. The datum from which the predictedheightsof tides are reckonedin tbe tide tablesis: a. given in the table 3 of the tide tables c. meanlow water D. the highest possiblelevel d. thesameas that usedfor thechartsof the tocality 37. Tbe interval of the averageelapsrI time from the meridian transit of the moon until the next high tide is called the: a. llarmonic constant c. Establishmentof tbe port D. Tide cycle d. Ilalf-tide lerrel 38. Which d tbe fi. is a referencedatun usedfor determining the depth of water as shown on an East Coastchart? a. Ilalf-tide level D. Mean .righ water c. Mean low water , d. Mean sealevel 39. The term 'flood curnent"refers !o that time when the water level is: c. Not changing 4 Moving towardsthe land D. Falling d. Falling becauseof a rapid changein the wind 40. Ibw many slack tidal curreng usuallyoccur eachday? D. TWo a. One c. Three

d. Four

41. In a river subject!o tidal currents,the besttime to dock a ship without the assistanceof tugs is: c. When the slac* water and stand coincide c. At stand b. At high water d. At slack water 42. Chafid depth is Oe: a. Vertical distanceftom the chart soundingdatumto the oceanbottom D. Vertical distancefrom Oe chart soundingdatumto the oceanbottom plus the height of tide c. Awrage height of water over a specifiedperiod of time d. Arerage height of all low watersat a plre 43. When utilizing a Pacilic Coastchart, the referenceplaneof sormdingis: a. Mean low water springs c. Mean lower low water D. Mean low water d. Lowestnormal low water 4. \\e drift and set of tidal stream,river and ooeancurents refer to the: a. Fosition & araof the current D. Speed& direction oward which the current flonn c. Tlpe & characteristicof the current's flow d. Noneoftheabove 45. The velocity of a rotary tidd current will be docreas€dwhen the moon is: D. At perigee c. New d. Full a. At apogee 46. The datumof sormdingsfc the Atlantic Coastof the United States,new in 1988is: c. meanhigh water spring a. meanlow water d. nean high water D. meanlower low water 47. WhicX of tbe following is fre correct definition of height of the tide? a. the vertical distanccfrom the tidal datum to the level of the warcr at any time D. the vertical diftrence betweenthe heights of low and high water c. the vertical diftreirce of darum plane and ooan bottom d. the vertical distancefrom tle surfaceof the water to tbe oceanfloor

12

Tldesand Cunents

4t. Mean high water is the averageheight of: a. tbhigherhighwater b. he lower higb water

c. theloneroftheg,pedqilytides d. all high waters

49. Which statementis true oncerning apogeantides? a. theyoccrn only at quadraturc D. they ocon when the moon is nearestto the eartb c. tbey causeddiumal tides o boome mixed d. tfuy bave decreasedftomnormal 50. The classof tide that prevails in tbe greatestnrtmberof important harbrs in the Atlantic Coastis: d. semidurnal c. diunml D. mixed a. spring 51. Neaptideomrs: a. at the sart of sp,ring,the sun is orrerthe equator D. only c/henthe srm,moon and earth are in line in any order c. when the sun and moon are 90 deg. relative to the earth d. when the sun, moon and eartb are in line, in any cder 52. Spring tide occurs: a. at the start of the spring, when the sun is over tbe equaor D. only wben the sun and moon are on the sameside of the earth and neady in line c. wben the sun and moon are 90 deg. relative to the earth d. when the sun,moon and earth are nearly in line, in any order 53. In order to predict the acnral depth of warcr using the fide Thbles,the da0aobained from the Tide ables: a. is the rcnnldepth D. should beaddedor subraced from the charteddepth c. shouldbe multiplied to the c,harteddepth d. shouldbe divi@ by the cbarteddepth 54. The velocity of current in large oastal barborsis: c. generallycolntant a. unpredictable d. generallytoo weak D. predictedin the tidal current tables 55. To makesureof gecing full advantageof a favorablecurrent,you shouldreachan entranceor strait at what time in relation to the frrediced time of the favorablecurent? c. 30 minutesbefore a. me hour after d. 30 minutesbeforeflood, one hour after an ebb D. at the predictedtime 56. A rotary current setsbrougb all direcfionsof 6e conpass. The time it takesto oompleteone of these cyclesis approxinately: d. ylhs0m c. l2t/znovs D. 6%hours a. 3hours 5?. A tidal currcnt which floun alternatelyin approximaEly oppositedirectionswith a slrck waterat each reversalof direction is called: c. tiderips a. reversingorrectilinear d. hydraulic D. bore 58. A current in a channelcansedbya difierencein the surhoe level at the two endsis called: d. hydraulic c. eddies D. bore a. reversing

Tldesand Currents

13

59. A quasi-circular mov€m€ntof wag whoseareais relatirrly small in conparison to the cunent with whie,hit is associatedis called: d. db c. ddy D. tide rips c. bore 60. In a &rv estuaries,the advanoe^f tbe low wat8r trough is so muc,hretardedthat the crestof Oe rising tide overakes the low, and advancesupsaeamas a chuning foaming wall of water is called a: d. hydraulic current c. hn, water b. tide rips c. bore 61. Which current would you en@unteron a dirirt passaSeftom SouthAftica to Argentina? d. SouthAtlantic c. Guinea b. SouthBquatorial a. Agulhas 62. Tbe main strean of the Califorrria current generallyseB in what directim? d. easterly c. westerly D. northerly o. southerly 63. The North Equatorial cunent flows o the: D. northeast a. southwest

c. *Est

64. Coriolis force affectsthe oean curr€ns as folloun: I. Coriolis force is grcater in higher latitudes. lI. Its efrectis grcater in deeperwater. c. bothlandrl D. tronly a. Ionty

d. east

d. neitherlnorll

65. Which of the following stat€mentsis/are correct regardingTide tables: I. The datum frm which the predictedheighB are reckmed is the sameas that usedfor the charts of the locality. tr. Tio find the actud deptb of the waler at my time, tbe heigbt of the tide is to be added to or srbtrrcted frm the charteddeptb. d. nei0er I or tr c. botb I and tr D. tr only c. I only 66. The set of tbe oceancur€nc is causedby: a. densitydifrere,ncesoftbewater D. dirpclionof prinrycirculationof air

c. rottrtimoftbeearth d. all oftheaborc

67. The height of oen waves: a. increasesif tbe samedfuecfionas tbe currents D. increasesas tbey approachlessdeepwater c. increasesas tby approachdeep€rwat€r d. remain constantin deepand sballw wator 68. Tbe curr€nt that is similar to the Gulf gts€amis the: c. O:tchio a. Kuroshio d. Bengrcla curr€nt D. Califffnia current 69. Equatorial comtercurrent gemally flmnc to tbc: c. w|cst D. south a. nortb 70. The moat efroctivegeneratingfacs of surfaceooeanqtrr€nB arc: a. temperatuF and saliniry difrrcnes in tbe water in the warer D. wind and density diftrtne c. wuer depth and |md€f*abr t0eosraDhy d. rotatim of tbe earth snd cm&cntel intcrfcrcne

t4

Tldesand Cunents

d.

ea!!t

71. On mid-ooeanwafers,the height of a wind-gen€ratedwave is not afiecredby: a. fetch c. water depth exeeding 100feet D. wind velocity d. duration of the wind 72. Which current would you encounteron a direct passagefrom london to Capetown? a. Norwaycurrent ,. Falklandcurrent c. Brazilcttrrent d. Benguelacurrent 73. Fetchis the: a. time in seoondsrequiredfor two creststo passa given point D. strerchof water over which a wave-foruringwind blmrs c. distaDcea wave travelsbetweenformation and decay d. measurpmentof wave steepness 74. You are oDa voJageftom NewOrleans to Bcton. When navigating offthe Floridaoast, you will get the greaest b€Defitftom the Gulf stneanif you navigate: a. about45 miles eastof CapeCanaveral c. dong the 50 fathomcurve D. about25 miles eastof Daytona d. closeinsbois 75. Wavebeight, length and period will dependupon: a. windspeed. c. lengthoftimethewindhasblown D. the fetch . all of tbe abore 76. The NombEquatorial current flows tothe: 4. *cst b. southwest

c. norltwest

77. lnwhich month will the Equatorial countorcunentbe the strongesc a. August D. April c. Oober

d. east d. January

78. When a cur€nt flows in the oppmite directi@ to the wave,tbe wave : a. lengtb is increased c. velocity inseases D. leng$ is unclanged d. heig[t is incrpased 79. The Br-azilcrrrent generally flows in which directim? a. sout[westerly D. southerly c. nortbwesterly

d. northerly

80. Cold wat€r flowing southwardthrough the westernpart of Bering strait betweenAlaska and Sib€riais joined by uater circtlating counterclockwisein tne nering seato form the: D. Oyashio a. Kuroshio c. Sub-arcticcurrent d. Alaska curent 81. Which is true staerent oncerning equatcial tides? a. Theymur when the sun is at maximum declinatio. D. They ocon when the moon is at ntaximlm declination. c. The difrerencein height betweenconsecutivehigh or low tides is xj minimrn. d, Ttey ue usedas the basis fa the vulgar establishmentof the port. t2. Yur vessclgm agroundin soft mu4 yur would havetle bestc,hanceof reflooting it on the next high tideif it is grunded at: c. highwaterneap d. highwaterspring b. Wetwarcrspring a. hlnwarcrn€ap cbops)will uually derrelopwbere the wind blows: 83. Tlie largestwav€sCheaviest c. in tle samedfu€ctio as tbe flw of the current a. at rigbt angle o tle fhry of tbe current d. ouerslactwat€r D. ageinst6efhoofthecurrent

Tidesand Cunents

15

84. The speedat which oceanwave systemadvanoesis called: D. ripple length d. wavelength c. groupvelocity

d. waveralocity

85. A current will develop betweenareasof different density in oceanwaiers. If 1ou face in the same direction the current is flowing, the water oft a. high density will be on the left in the N. hemlsphere D. low density will be on the left in tbe N. hemisphae c. high density will be on the right in the S. hemispbere d. bw density will be on the left in the S. hemisphere 86. One of the causesof oceancurrentsis density difierenes in the water. This is true because: a. in an areaof high density the water surfaceis lower than the areaof low density D. surfacewater flows ftom an areaof high densityto arealow density c. the lesserthe density gradient the freeier the water d. density differencescausethe curents to stayin the trough 87. Generally speaking,a ship steaning acrossthe N. Pacilic oean from Japanto Seattleis likely to experience: c. favorablecurrent in the summermonthsonly a. adversecurrentsfor the entire sossing d. variable cunents D. favorablecurrent fo the entire crossing 88. When a current flows in the oppositedirection to the wave: c. velocity increases a. length is increased d. length isunchanged D. height is increased 89. Coastalcurrent: a. is generatedby wavesstriking the beach b. flows outside the surf zone

c. flows in a circular pattem d. is also hown as longshorecurrent

90. Which of the following curcnt is r€sponsiblefm themovementof ioebergsino the N. Atlantic shipping lanes? d. Baffm current D. Baltic curent c. Labrador current a. Iceland current and no well defmedcurrents.This areais in 91. In the Sargassose4 thereare largequantitiesof seaweeds the: c. rilestern N. Pacific ocean. a. Central N. Atlantic ocean d. WestcoastofS. America b. Caribbeansea 92. The cold oceancuffent which meetsthe wam Gulf streambetweenlatitude 40 deg.and 43 deg.N to form the "oold wall" is the: c. N. Pacific current d. California curent a. Labrador current D. Alaska current 93. As the SouthEquaorial curent approachesthe eastcoastof Africq it divides with main pa$ flowing southto form the warm: c. Madagascarcurrent d. Canary current D. Benguelacurent a. Agulhas curent 94. What curent flows southwardalong the west coastof Oe United Statesand causesextensivefog in that afea: d. Califomia current c. N. Pacific curent a. Davidsoncurrent D. Alaska current "w^rm" basedon the latitude in which it originates: 95. Which of the following currentsis d. Perucurent D. Sub-arcticcurrent c. Kuroshio c. Alaska curent

16

Tldestnd Cunents

!)6. The Brazil current flows in which direction? D. southwesterly c. northwesterly

c. southerly

d. northerly

97. On a voyagefrom New York o Durban,yon shouldexpectthe Agulhascurrent to prcsenta strong: c. headcurrent D. onshoreset d. following current a. ciffshoreset 98. You are anchoredin tbe Aleutian island chain and receivedword that a Tsunamiis expectedto strike the islands in six hours. What is the safestaction: a. Get undenvayand be in deep,op€noceanwaterwhen the Tbunamiarrives. b. Increasethe scopeof the anchorcable. c. Get undenvayand be closeto the shoreon the side of the island away from the Tsunami. d. Plant both anchorswith about a 6Odeg. anglebetweenthem. 99. Which of the following shoutdyou expectwhen you enoountera Tsunani in the openocean? a. violent seasfrom mixed directions D. no noticeablechangefrom the existing seastale c. wind increasingto gale force d. amEor wavewith extrerre height and length 100. Which of the following statementsabout the rate of rise of the tide is/are correct? I. The rate of rise is not uniform. IL The tide risesfastestwhen it first startsto rise. c. both I and tr d. neitber I nor II D. II only a. I only 101. High tide on a coastlinelag behind the meridian transit of the moon due to: I. The revolution of the earth II. The rotation of the earth d. neitherlnorll D. tlonly c. bothlandtr a. Ionly 102. Your draft in a channel is 39.5 feet. Wbat is tbe depth in metersyou can clear the bar at? d. 21.87m b. l2.l9m c. l3.l7m a. 6.58m 103. The depthof water on a cbart is indicatedas 23 meten. This is equal to: d. 78.6fea c. 69.0feet b. l2.6fathoms a. ll.5 fathms 104. Thirty-twometersis equalsto: b. 58.52tet a. t7.50tes

c. 96fa.

d. lm.99tff,t

105. You are rmderwayin a vesselwith a draft of 6.0 feet You arein an areawherethe charteddepthof the water is 4 fathoms.You should expoctthe deptb of waterbeneathyour keel 3ob approximat€ly: d. l8feet c. 2/-fer,t b. 30tert a. l2fet 106. The heavenlybody that has the greaterinfluence on tide is Oe: c. Planet D. Star a. Sun

d. Moon

107. Theyare causedby meteaologicalhctors suchaswind andbarometricpressureandby oceanographical ftctors suchas difierent sdinity of water and temperature. d. Currents c. Swells D. fides a. Wavcs 108. Wnds blowing along a c@st tend to set up long waves which travel along tbe omst raising the sea level at the crcct and lowering the sealevel at the trough. Thesewavesare known as: d. Ripples c. Tidal waves D. Coastshakers c. Storm surgps

Tidesand Currents

l7

109. A phenoaenon surely not an indication of an approachingtropical storm. d. Ilalos around the mmn c. Tidal wave a. tong high swell D. Ctoudsin the *y ll0. It is the result of an underseaearthquakewhich setsup wavesentirely rmconnectedwith tides and travels with a great speed. d. Breaker c. Eddy D. Tidal wave a. Swell 111. Which of tbe ff. stat€mentsis tfue? a. A low barometricprcssurewill tend to raise the sealevel. D. A low barometricpressuretendsto depressthe sealevel. c. A high brometric prc$ilre will raise the sealevel. d. A low or high pressur€doesnot affect the sealevel' 112. The curr€nt coming from high latitudesnorth or south going towardsthe equator.. d. Bquatorial current c. Cold current D. Polar current a. Warm current 113. The movementof water coming in towardsthe shoreor up streans: c. High tide b. Flooding a. ffiing

d. Slacking

114. A level of the sea,defined by somephaseof the tide, &om which waler depthsand heightsof tide are reckmed. d. Tidal day c. 'fidal wave D. Tidal datum a. Tidal cunent 115. What currcnt increasesthe speedof a vesselover the ground? b. Favo'rablecurrent c. Favorablewind a. Favorableline

d. Fathometer

116. A tidal current having one flood current and one 6b current eachtidal day is: c. Diurnal inequality d. Diunal motion D. Diunal circle a. Diurnal curent 117. The Humboldt Current flows in which directim? c. South D. North a. West

d. East

ll8. The wabrs of the North Atlantic entering the Arctic Ocean,betweenNorway and Svalbar4 is which current? d. Polar curent c. Northem curent D. Monsoo current a. Oean qrrrent 119. A relatively natrox,, deep,fast-moving curent is sometimescalled: c. Windcurrent b. Driftcurrent current a. Hff1dy

d. Streamcurent

120. What is the diflerence betrveenthe time or heigbt of tides at a subordinatestation and its reference station? d. Tidal difrerence c. Tidal wave b. Tide a. fidal day 121. ThedeflocfiondawinddrivencurrentstotherightofthewinddirectionintheNorthernllemisphere is carsedby c. The polar ice caps a. The Coriolis fore Variability d. cunent D. Sub-surhc 122. Wbatdetermines the mosteffects on iceberg? c. Waves a. Currens d. Wnds D. Tides

rE

Ilfus and Currents

123. What is the higher of two low tidesocctqing during a tidal day? a. Higher low water D. High tide c. Higherhigh water d. High meanwater 12t1.What is a short" breaking wave occurring when a current passesover a shoal or other submarine obstructionsor meetsa contrary current or wind? b. Overfall a. Overflow c. Overshore d. Coastalwave 125. What is the place at.which continuoustide o.bservations are made over a number of yearsto obtain basictidal data for the locality? a. Tide tables c. Secondarytide station b. Primary tide station d. Tide vessel 126. The instrumentwhich registerstheheightof the tide againsta scaleof thetide daa which is recorded for the actual reading oomputationis called: a. Barograph c. Automatictide range D. Thennograph d. Tidal graph 127. T)nedifferencebetweenthe heightof the two high tidesduring a tidal day is called: c. High waterfull and change c. High water inequality b. High water d. High water mark 128. An o@ancurrentflowing rougbly parallelto a coastoutsidethe surf zoneis called: a. Driftcurrent c. Offshorecurrent D. Longshorbcurrent d. C-oastalcu:rent 129. Either a tsunamior a stormtide that overflowsthe land is calleda: a. Tide D. Current c. Stomrcurrent

d. Tidal wave

130. What is that part of the tide duesolelyto the tide producingforcesof the sun? a. Solartide b. Equatorialtide c. Apogeantide d. Perigeantide 131. It consistsa singlewavecrestand hasno periodor wavelength. a. Stormtide b. Stonnsurge c. Tidalwave

d. lttofthese

132. Ihe time interval betweennew or full moonand the maximum effectof thesephasesupon therangeof tide. a. Ageof tide c. Vulgarescablishment D. Lunitidal interval d. Diurnal interval 133. The part of theEquatorialcurent that haspa.ssed throughthe Gulf of Mexico andhasbeendeflected by land. a. Gulf Stream D. LabradorCurrent c. CanaryCurrent d. BenguelaCurrent 134. The horizontaldistancebetweensuccessive troughsmeasuredin the directionof travelis termedas: a. Wavelength b. Waveheight c. Waveperiod d. Wavevelocity

135.Theintervaloftheaverageelapsedtimefromthemeridiantransitofthemoonuntilthenexthig is called: a. Lunitidal interval c. High water ,. Establishmentof the port d. Ageof tide

Tidesand Currents

19

136. The difrerencebetweentbe level of the danrmof chart and of the meanhigh waterspring is known as: a. Neaprise D. Tiderise c. Springrise d. Diurnalrise 137. The time interval benveenthe passageof successivewavecrestsat a stationarypoint is called: a. Wavelength D. War fieight c. Waveperid d. Waveralocity 138. The trade winds which blow with great persistence,set up a sysbm of Equatorial current which at times exiendsto latitude 50". This current is called: a. Atlantic oceancurent c. Streamcurrent D. Counter current d. Drift current 139. Wavescausedby stonns that continue on without relation to local winds. a. Swells D.. Sea c. Gravity,waves d. Noneof these 140. It is a wavein which only the fonn advances,the individual particlesof the mediummoving in closed mbits, as oceianwavesin deepwater. a. Waveof translAtion c. Gravity wave D. Oscillatory wave d. Tidal wave 141. It is a wavein which tbe individual particlesare shiftedin the direction of wavetravel, asooeanwaves in shoal water. a. Waveoftranslation c. Gravitywave b. Oscillatorywave d. Noneof these 142. T\e point directly abovethe disturbane, at whicb the wavesoriginated. a. Epicenter D. Geocenter c. lleliocenter d. Me,trnnter 143. lt is the continuation of the South Pacffic Equatorial Current after its division near the Fiji Island. b. StreamCurrent a. Rmsel curent c. Austrdian Current d. Rotary current 144. A suddenand temporaryoscillation or fluctuation of the water level in a land-lockedpart of the sea b. Seine a. Seiche c. Seineboat d. Seinefloat 145. The BenguelaCurrentflows: a. Southwestertyalong the SE coastof Greenland. b. Southwesterly alongthe SW coastof Greenland. c. Southwesoerly alongthe NW coastof Africa d. Northwesterlyalong the SW coastof Africa 146. Kuroshio Current is affecting your vessel.Yo will be carried by the current to which direction? a. To the southand west c. To the north andeast b. To the north and west d. To the south and east 147. Approximately,how much of the earth's surfaceis coveredwith water? D. Tho-thirds a. Three-fourths c. One-third d. One-fourth 148. Portsof Norway on the Atlantic Oceanare usually ice-ftee during winter becarseof the effectsof: ,. 'Iatitude c. Topography d. Migratory cyclones c. Oceancurrents 149. At a depth of 3 meten in the ocean,the pressureof the waterwould be approxinately: D. 3 millibars a. 30 millibars c. 30 decibars d. 3 decibars

20

Tidesand Cunents

Tlu pessure exettedby I nwter of wateris eqwl to I decibar.Tln pressurehdecibars is approximatcly tlrc sameas thc dcpth in meters. 150. In the SouthemHemisphere,the oceancurrent that comptetelyencirclesthe earth is the: a. Equatorial counier qurent c. Southequatorialcurent D. Westwind drift d. Fast wind drift Westwind drifi is also knownas A trARcrrccrRcuvtpotAR cuRnENT. 151. On which of tbe following doesthe densityof seawaterdepend? Answer: Salinity, temperatureaad prcssure. 152. The most imporhnt &etor in causingvriations in soundvelocity in the upper fuw hundredf@t of the o@an. Answer: Dewity. Thethree variables governing tln speedof the soundin afluid are density,compressibility,and tlte ratio betweenthc specific luus of tlu fluid at constantpressureand at constanivolume. 153. The instrumentthat recordstemperatureagainstdepthas it is loweredinto a bodyof wateris called: Answer : Bathytlurmograph Temperatureu any desireddepth can be determinedby nwansof reversingtlurmometer. 154. The physicalpropertiesof oceanwaterwhich is characterizedby theamountof dissolvedmatterin the water is known as: Answer: Salinity 155' At a given teNnperature and pressure,which of the following samplesof sea water would have the greatestdensity? a. Onewith a salinity of 35 partsper thousand b. Onewith a salinity of 37 parts per thousand c. One with a salinity of 33 parts per thousand d. Onewith a salinity of 31 para per tbousand Answer: (b) 156. Which of the following is not a part of the Gulf Streamsystem? a. Antillescurrent f. Ftoridacurent c. Gulfsream Answer: (a)

d. NorthAtlanticcurrent

157. Bodiesof water show lessvariation in temperaturefrom seasonto seasonbecause: Answer : Heat is distributed through thc water by vertical and horizontal currents. 158. In general,the salinity of the oceanis approximately: Answer: 33 0/00 to 37 0/00 159. In general,the oceantemperaturerangesapproximatelyfrom: Answer: -2 "C to 32 "C 160. The processof obtaininga modulatingwavefrom a modulatedwave. Answer: Demoduluion

Tidesand Currents

2l

: 61. Which of the following is not a relatively cold current? c. PeruCurrent a. East Ausralian Current d. California Current b. C-anaryCurrent Answer: (a) 162. Which of the following is not arelativelywarm crrrrcnt? c. Falkland Current a. MozambiqueCurrent d. Btaziltan Current D. Guinea Current (c) Attsviter: 153. The relatively cold current which flows along the northwestcoastof Africa is the: .4nswer: CanaryCunent f,i4. The Coriolis ForcecausesooeaDcunents to circulate: Answer : Cloclcwisein tlw North Latitudes. 155. The North Atlantic cutrent sets: ,[nswer: fustward 1ti6. The Davidsoncurrent flows: Answer : Nortlwrly along tle Cahfomia coast. l( 7. An oceancurrent is primarily causedby: Answer : Prevailing wind168. The Benguelacurent sets: Ansver : Nortltward along tlw westcoast of Africa 16). Indian Oceancurrents: Answer : Have direction changeaccording to thc rnonsoon* 17'). The North Pacific curent sets: Answer: hsterly.

22

Tidesand Cunents

Weather is the stateof the earth's atmospherewith respectto temperature,humidity, precipitation, visibility, cloudiness,etc. Cllmate refers to the prevalent or characteristic meteorologicalconditions of a place or region. The Atncphcne. A relatively thin shellof air, water vapor,dust, smokg etc. surroundingthe earth. Thoposphene.That portion of the atnospherefrom the earth's surfaceto the tropopause.It is characternedby deoeasing temperaturewith height, appreciablevertical wind motion, appreciablewa0ervapor contentand weather. Thopopause.The boundarybenreenthe roposphere and sratosphere. Stratosphere. The atmosphericshell extending upwardftom the tropopauseto the height wherethe temperaturebegins to increase in the 20-to-25 kilometer region. Jet Stream. Refers to relatively strong (60 kts.) quasi-horizonal winds usually concentratedwithin

a restrictedlayer of the abnosphere. Geostrophlc Wlnd. That horizontal wind velocity for which the Coriolis force exactly balancesthe horizontal pressureforce. Gradlent Wlnd. Any horizontal wind velocity tangent to the contour line of a const4nt pr€ssure surface(or to the isobaror a geopotentialsurface)at the point in question. hcssure Gradlenl The change in pressurewith horizontal distance. Front is the zone of separation benreen two air Ilusses. Warm Front Wamer air is replacing colder air. Representedas red line. As the wamr front passes, temperaturerises, the wind shifts clockwise (N. Itremisphere)and the steadyrain stops.Thepressure might slowly decrease. Cold Front. Colder air is underrunning and displacingwarrnerair. Representd asblue line. As the fastermoving, steepercold ftont passes,thewind

Sequenceof Weatherat a WarmFront Element

ln Advance

At the Passage

ln the Rear

Pressure

Steady|all

Fall ceases

Uttle changeor slow fall

Wnd (norlhem hemisphere)

Increasingand sometimes backinga little

Veerand sometimes decrease

Steadydirection

Temperature

Steadyor slow rise

Rise,but not very sudd*r

Uttle change

Clord

Ci, Cs, As, Ns in succession; scud belowAs and Ns

Low Ns and scud

St or Sc

Wealher

Continuousrain or snqY

Precipitatlonalmostor completelystops

Mainlycloudy, olhetwise drizzle,or intermittent slight nin

Msibility

Very good except in precipitation

Poor, often mist or log

Usuallypor; miotor log may persist

23

shifts cloctwise (N. Hemisfere), temperetureftlls .Occluded Front. A faster moving cold front rapidly; and tberp are often brief and smetimes orertakes the warur ftont. Representedas purple violent shon€rs,ftr4uently mpanied by thunder line. and lightning and squalls. Stadonrry Fnont. A front which is stationary or After a cold ftont passes,the pressure rises, nearly so. Representd as alternating red & blue visibility improvesand the clouds tend to diminish. line.

Sequenceof Weatherat a Cold Front ln Adrrarrce

Elemant Pressure

Fall

Wind(norlhem lncreasingand backinga hemisphere) litte, oflen becomirB squally

At the Passage

-

In the Rear

Suddendse

Rise continuesmore slowly

Sldd€n veerand sometimeshealy squall

Backinga little after sqmll, thenolten strengthensand may steady or veer further in a later sqtall

Temperature

Steady,but hll in prefrcntalrain

$dd6n hll

Uttle change or perhapssteady falh variable in showers

Cloud

Ac orAs, hen hevy Cb

Cb wi|h low scud

Lifting rapidly,followedby As or Ac; later,lurtherCu or Cb

Weather

Usuallysome nin; pefiaps thuder

Rain, often heavy, with pefiaps thunderand hail

Heavy rain lor short period but sometimesmore persistent, then mainlyfair with occasionalshower

Msibility

Usuallypoor

Terponry deterioration iollowed by rapld improvement

Usuallyvery good exceptin showers

LOCAL WINDS Land and SeaBreezcarecausedby altematebeating and cooling of land adjacent to water. By day the land is warmer than the water, and by night it is cmler. ScaBrecze. During the day, the lower levels of air over land are warmed,and the air rises, drawing in ooler air from the sea Land Breeze. After $mset, as the land coolsbelow the seatemperature,the air aboveit is also ooled. The contracting cool air becomesmore dense, increasingthe pressurenear the surfaceresulting in an oufilow of winds to tbe sea.

24

Anabatlc Wlnd. Wind that blows up an incline asa result of surfaceheating. Katabatlc Wlnd. Wind thatblowsdownan incline. There are two t),pes,FOEHN and FALL WIND. foehn. A dry wind with a downward oomponent, warm for theseiason. Occurswhenhorizontallymoving air encountersa mountain barrier. Known as CHINOOK in theRocky MountainRegion. Fall lillnd. A cold wind blowing down a mountain slope.

WeatherElements

SOMELOCAL WINDS l. Bon. A cold, dry katabatic wind which ftom directions varying betweennorth and brq anL doq.nftom &s 6eunrains of the north and east fu€s of the Adriatic. It is often dangerous.The rind cming down in violent gustsfrom the moun-

wind c a gale asmciarcdwith a depression)in the Persian Gulf, the Gulf of Oman and along the lvlakran mst" 13.Sotherly Busier.TheS windbehindtbeold ftont in a trough of low pressureoften starts with a violent squatloffthe SE coastof Australia

FirL(.

2. Tbhuantepecer.A violent squally wind from N a NE in the Gulf of Tehuantepec(S of southern Mexico) in winter.

I4.$mtra. Squallsfron SW. Occur several times a month between Itfay and October in the MalaccaSts.and W. cmst of lvtalaya

15.Bllzzad. A violent,intenselyooldwind laden 3. Pampero.Line-squalloccuringat thepassage with snon, mostly o1 entirely picked up from the of a sharp cold front in the Argentine coasts.It is gound. Any havy snowfall accompaniedby sfong usrally accompaniedby rain, thunderaadlightning. wind. 4. Mlstral. A col4 dry wind blowing fron the north orrerthe NW coastof the MediterraneanSea (Gulf of Lions). 5. Eteslan. The summer winds of Agean Sea andeasternMediterraneanwhich blow with considerableconstancyfrom a northedy direction. 6. Gregale. A strong NE wind blowing in the central and western Mediterranean(Malta & east mstof Sicily). Occursmainly during winter. 7. Harmattan. A dry E wind which blows on the west coastof Africa betweenC. Verde and the Gulf of Guinea,in the dry season.

16.Ihlst lVhtrl. A rotating cohrrnnof air about 100 to 300 feet in heighl carrying dust,leavesand other light materials.Called as dust devil in southwesternUnitedStatesanddesertdevilin S. Africa 17.Gnst A suddenbrief increasein wind speed followed by a slackening, or the violent wind or squall that acconpaniesa thunders0orm. 18.Cat's Paw. A putr of wind or a light beezn afiocting a small are4 v/ould causepatchesof ripples on the surf;aceof tbe water.

\tlaterspout A surall whiding storurover the cean 8. Khamsin. A southerlywind which blows in or inland waters. Egyptand in the RedSeaaheadof eastward-moving Tbnnadocs.Theseare derived from violent @nvecdepressions. tive stormsover land and moving seaward. 9. Levanten An E wind in the Stnaitof Gibrattar. Brings excessivemoistur€, cloud , haze or fog, Monsmns (seasonatwlnd). A wind systemproduced by the alternateheating and cooling of a landnass. and sometimesrain. l0.Norther (of Chile). A Northerly gale, with rain, which oocursusually in winter. Northcr (of Gulf of Mextco). A strong,cool, dry N wind whicb blowsover the Gulf of Mexico and W. Carribeanin the winter. 11.Slrocco. Any Southerlywind in tbe Mediterranean. Hot and dry wind originating from the desertsof N. Africa

Summer Monsoon Blows from SW from IUay to October. I4{nter Monsoon Bloc/s ftom NE frm Octoberto April. In the Bay of Bengal and Arabian Seq the SW monsoonis strongerand more stormy than the NE monsoon.

In the China Sea the winds are stronger and l2.Shamal. Any NW wind (normal prerrailing steadierin the NE rnns(x)n.

WeatherElemen*

25

over water or land.

AIRMASSES

A third classification sometimesapplied to tropical and polar airmass indicating whether the air mass is warm (w) or old (/c) relative to the underlying surfa@, and cPk indicates ontinental polar air whlch is coldertbanthe rmderlyingsurface. The w andlcclassificationsareprimarily indications of stability (i.e., change of temperature with increasingheight). If the air is cold relative to the Ainnasses61t.nemed aocordingto their souroe surhce, the lower portion of the airmass is being of regions (1) Equatorid (E), the doldrum area be- hearc4resultingin insability (temperaturemarkedly tweenthe north and south trades;(2) Tropical (T), decreases with increasingheight) as the wanner air the tradewind and.lowertemperat€r€gions;(3) Po- t€ndsto rise by convection. Conversely,if the air is lar (P), the hilher temperatelatitudes; and (4) Arc- warm relative o the surface,the lower portion of tic or Anarctic (A), the north or southpolar regions. the airmass is cmled tending to remain closeto the surface. This is a stable condition (temperature Aimu$ses are further classiftedasmaritime (n) with increasingheigh$. increases or continental(c), dependinguponwhethertbeyfum

Airmass is an extensivebody of air with fairly unifcm (horizontal) physical properties,especially temperahreand hmidity. In its incipient stagethe p'ropertiesof tbe airmassaredeterminedby tbe characteristicsof the region in which it forms. It is a cotdorwamair massasit is colderor warmerthan the surroundingair.

NARTH-rotE

fFvaruNC f i

,

ryES{lt!|ES

HAFSEL{TITUD6

HIqH PR€.S\gJRE

D4-DRUIlS ( \ /IISH fPfrgs,URE

\\ T'I'RSEGTTruDES

PRE\ALINO

€4.ITH RruE

O F T H EG E N E R A L S I M P L I F I ED DI A G R A M C I R C U L A T I OO NF T H EA T M O S P H E R E

26

WeatherElements

Ihe DoHrms is the zone of light and rariable winds, often associated with heavy rain or thunderstorms, which form a narroq roughly lati$dinal, belt aotpying a position betweenthe equatorand aboutl:it.12" N or S. This is the zme wbere the trade-wind systemsof the northern and / southernhemispheresconvergetogether. Ihe TbedelVbds at the surfaeblow from belts of high pressure oward the equatorial belts of low prcssure.Becauseof the rotation of the earth, the moving air is denectedbward the cest. The trde winds in the Northern Henisphere are called northeast trades while those in the Southern Ilemisphereare called soutlteasttrades.

proportional to the pressuregradient Dcprcslon or Low. A depressionor low-pressure systemis a region of relatively low pressurewith closedisobars.The isobarsformaclosed systemwith the lowestpressureinside that isobarwhich has the smallest value of pressure, the wind circulation arounditbeing anticlocklise in the N. Ibmisphere and clockr*,isein Oe S. Hemisphere. Sccondary Deprcsslon A $ndl depressionwithin the areaovered by a larger primary depression. lhoug! oflow Pressure.A rough is an elongated areaof low pressureindicatedby isoban extending outwardsftom a depression.

Ihe Horse Ladbdes (sr.nrnoplclt HIctl-PRBssuREAntlcyclone or lllgh. An anticycloneor high is a relr) are zonesoflight and vatiable winds and fine regionof rclativelyhigb pressurewith closedisoban. clear u/eathermarking the entrd regions of the The isobarsfom a closel systeNn with high pressure subtropical high pressurebelt. They are mainly on the inside, the wind cinculationbeing clockwise locatedin aboutLat. 30"-35" N and S. in the N. Ibnisphere and anticlockwise in the S. Itremispherc. hevalllq Westerlles. On the polewardside of the high pressure belt in each hemisphere the Rldge of lllgh hessure. An elongatedareaof high aunosphericpressureagaindiminishes.The qrrents pressureindicated by isobars extending outwards of air setin motion along thesegradientsoward the from an anticyclone. polesare divered by the earth's rotation toward the east,becomingsouthwesterlyin the N.Hemisphere Col. A saddle-backedregion betweentwo lows and and northwesterlyin the S. Henispbere. The bois- two highs. terouswild oocuringin Latinrdes40" S to 50" S (or The weatherthat characterizedthe depresslon 55" S) are called the roaring forties and they are is srong winds, densecloud, and rain or snon. The strongestat about Latitude 50" S. central region of most antlcyclones is one of light Whds of Poler Reglons"Thewinds blow outward ftom the poles and are deflectedwestwardby the rotation of the earth, to become,nrtluasterlies in the Arctic andsoutluasterlies in the Antarctic.

winds and fair weatherfor the subtropicalareasand for temperatelatitudes.

The trurgh is a region ofoonvergenceand tends o be associatedwith densecloud and precipitation. Some troughs tend to remain stationary for long periodsin temperatelatitrtdes,particttladyin summer PRESSUREAND WINDS when the upper air circulation patt€rn is weak. In Theair circulatesclockwiserormdcent€rsof high thesecircumstancesupather is mostly cloudy with pressureand anticloclwise round centers of low local showers and thunderstomls, which may be pressurein the N. Hemisphere(while in the S. heavynearan activefront. In tropical latitudes,lowlhmisphere tbe air circulario is mticloclwise rumd pressure troughs are regions favorable for the centersof high pressrneand clockwiseround centers developmentof tropical stonns in certain oceans. of low pressure). A rHgc of hlgh pne$ure is a systemof curved The wind is srrong where the pressuregradient bobrs in which pressureis higher on the insidethan is steep and light where the pressuregradient is on theoutside.Fineweatheris associatedwith a ridge small, that is the speed of the wind is closely of high pressure.

WeatherElemcnts

n

A col is the region betweentwo ridges of high pressureandtwo trougbsof low pressure.No definite weathercan be associatedwith a col. it is a region wheresharpchangesoccur.

TROPICAL CYCLONES

'

CII\SSIFICATION: Thoplcal Dlsturbance is a discrete system of apparently organized convection. It has no strong windsand no closedisobars.Also known aseasterly wavGs.

Thoplcal Deprrsslon hasoneor moreclosedisobars and some rotary circulation at the surface.The highest sustained(l-minute mean) surfacewind speedis 33 knots. Tboplcal Storm has closed isobars and a distinct rotary circulation.The highestsustained(l-minute mean)surfacewind speedis 34 to 63 knots. Hurr'lcane or\phoon hasclosedisobars,a strong and very pronounced rotary circulation and a sust4ined(l-minute mean)surfacewind speedd 64 knots or higher. PRECT'RSORYSIGNS l. A long low swell is sometimesevident, prcceedingfrom the approximatebearingof the centerof the storm. 2. Cimrs cloudsappearing0odiverge from a point on the horizon may indicate the direction of a ropical stonn. 3. An appreciable change in the direction and strengthof the wind. 4. Corrected barometerreading is 5 mb or mor€ below the normal.

4uvs

CIRCULAR AREA OF THE STORM Dangerous Semlclrcle. The actual wind speedis greatf,rthan that dueo tbe pressuregradientalone, since it is augnented by the forward motion of the stonn and the direction of the wind and seais such as to carry avesselinto the path of the storm. Navlgabh Semlclrcle. Tbe wind is decreased by the forward motion of the storm, and the wind blows vesselsawayfrom the storm track. NORTIIERN IIEIVI$PIIERE If the wind is rrcering,the shipis in theDangerous Semicircle.If the wind remains steadyin direction or nearlysteady,the ship is in the path of the sorm. If the wind is backing, the ship is in the Navigable Semicircle. SOUTEERN HEMISPHERE If the wind is veering, the ship must be in the DangerousSemicircle. If the wind remains steady in direction or nearly steady,the ship is in the path of the storm. If the wind is backing, the ship is in the Navigable Semicircle. Vecrlng whd. A wind changing direction to the right in the Northern Hemisphereand to the left in the SouthernHemisphere. Backlng wlnd. A wind chmging direaion o the left in the Northern Hemisphereand to the right in the SouthernHemisphere.

MANEUVERING TO AVOID THB STORM CENTER

BALLors LAw

If an obserrrerin the N. Ibmisphere facestbe surfae wind the center of low pressureis toward his right, somewhatbehind him; and the center of high pressureis toward his left and smewhat in ftont of hirn. If an obserrrerin the S. lbmisphere frces the surfacewind the centerof low pressureis towardhis left and smewhat behindhim ; andthe oenterof high

2E

pressureis toward his right and somewhatin front of him.

NORTMRN IIEM]SPIIERE Rlght on DaqgernusSemlclncle"Bring the wind on the stbd.bqp, holdcourseandmakeasmuchuay as poosible.If obliged to heaveto, do so with headto the sea Left or Navlgable Scmtclrcl€. Bring the wind on the stbd.quarter,hold cornseandmakeasmuchway

WeatherElements

as possible.If obliged to beaveto, do so with stern to the sea

prepredness is rctivated to dert status.

On StormlhackrAhcad of Center.Bring tbewind two pts. on the stbd. quarter,hold courseand make as much way as pcsible. When well within Oe navigablesemicircle,maneuveras indicatedabove.

PI,BLIC STORM SIGNAL NO. 2

On Storm Thack, Behlnd Center. Avoid thecenter by the bestpracticablecDurre,keeping in mind the tendencyof tropicd cyclom to qnre northwad and eastward.

bourrerur HEDTTsIPHERE Left or DangerousScmlclncle. Bring the wind on the port bow hold courseand makeas much way as possible. Rlght or Navlgable Scmlclrcle. Bring the wind on the port quarter,hold ourse andmakeas much way as possible. On Storm Thack, Ahead of Centen Bring the wind tlo points on the port qtr., hold courseand make as much way as possible. On Storm Thack, Behtnd Centen Avoid thecenter by the bestpracticableoouree,keeping in mind the tendencyof tnopicalcyclonesto curvesouthwardand eastward.

PUBLIC STORM WARNINGS Storm slgnals are raised during the Tropical Cplone Warning stage.In May 1991, PAGASA introdrrced a new system in its cyclone warning s€rvices,the Modified hrblic Storm\ilarning System (MPSWS). Thi MPSWS involves the addition of Public Storn Signal No. 4 and enhancedthe descriptionof eachsignal. PT'BLIC STORM SIGNAL NO. 1 A tropical cyclme will affectthe locality. Winds up to 30-60 KPH may be expectedin at least 36 houn. Tbigs and branchesd small trees may be hoken. Somebananaplants may tilt or land fliaton the ground. Very light or no damageat all may be sutainedby the exposedcommrmities. Businessmay be carried out as uual. Disaster

A moderate tropical cyclone will affect the locality. Wnds of greater than 60 KPH and up to 100KPH may beexpectedin at least24 bours.Sme @conutrees may be tilted with few othersbr,oken. Few big trees may be uprooted. Many banana plantation may be destoyed. Sone old galvanized iron roofmgs may roll d. Large numbersof nipa and cogon houses may be partially or totally unroofed.The seaand coastalutatersare dangerous to smaller sercraft Fishermenare advisednot to go out to sea.Disasterpreparedness agenciesand other organizationsare alerted. PT'BLIC STORM SIGNAL NO.3 A strongAopical qdone will affect the locality. Winds grc:rterthan 100KPH up to 185KPH nay be expectedin at least l8 hours. Almost all bananaplants may be destroyedand a large numberof treesmay be uprooted.Rice and corn crops may suffer heavy demage.Majority of nipa and cogonhousesmay beunroofedor desuoyed and theremay be considerabledamageto structures of light to medium construction. There may be widespread disruption of electrical power and communicationsservices.Seaandcoasal waten will be dangerousto all seacraft Feopleareadvisedto evacuateand stayin strong buildings.Evactatelow-lying areas.Stayawayfrom coastsand river banks.Warchout for the passageof the eyeofthe typhoon. Thepassageof theeyeof the typhoonis indicated by a suddenchangefton bad to fair wea0er. Fair weatbermay last fc one or two hours after which theworstweatherwill restme with rrcrysrong winds generallyooming from Oe oppositedirection. Disasrcr preparednessand responseagencies/ organizationsarerctivated to respondappropriately. PT'BLIC STORM SIGNAL NO. 4 A very intense typhoon will affect the locality. Very strong winds of more tban 185 KPH may b

WeatherElements

29

PATHSOF TROPICALSTORMS

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PARALLEL TRACK SEARCII PATTERN -FOUR

SHIPS

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b:

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STEEL PLAIE Each %" thicknessweighsl0 pounds

STEEL WIRE ROPE BreakingStrengthin pounds = 55270xD'

Cargo Gears

357

STRENGTHOF ROPES MANILA ROPE 1.

Given a 3-inch Manila rope, ostimateits ultimate strength (breaking strength) and safe working loads. SOLUTION: USoTBS

=

C2 3

=

9 3

or USoTBS

=

C2 L5

=

= ) L5

=

) 7

=

9 13

For occasionallifts: = C2 SWL 7

=

=

3 tons 3.6tons

l2ltons

For continuousworking: SWL 2.

=

C2 18

Vzan

A Manila rope that hasa 2.5 inch circumferencewill breakat: SOLUTION: BS

3.

=

C2 = L5

2.5 x2.5 L5

=

2.5 tons

Find the size of smallestManila rope suitablefor load of 3 tons. SOLUTION:

4.

,rf7 x toad

=

Sizeof rope C

=

,nE

=

4.6 inch

Using a factorof 5, what is the SWL of a Manila rope that hasa bneakingstressof l2.l tons and a circumferenceof 5.5 inches? SOLUTION: SWL

5.

=

BS

=

s

F

12.1tons =2.42tons

5

Find the block sizeand the sheavedianeter to be used with a 3-inch Manila rope. SOLUTION: Sheavediameter= ZxC Blocksize = 3xC

6.

= 2x3 = 3x3

= 6inches = 9inches

If the 3-inch Manila rope was usedfor 2000 lbs. of weighf what weight would 1ou lift with 3-inch sisalhaving 80% of the Manila rope? SOLUTION: Weight = 2000ltts. x 0.80 = 16001bs.

3sE

Cargo Gears

WIRE ROPES What would be the breakingstressof 2-inch wire ropeshaving 12, 24, and37 wires in eachstrand? l. SOLUTION: ( l 2 w i r e s B) S = 2 C 2 = 2 x 2 x 2 = 8 t o n s ( 2 4 w i r e s )B S = 3 C 2 = 3 x 2 x 2 = l 2 t o n s (37wires) BS = 3.25C2 = 3.25x2 x2 = 13tons Z.

Find the ultimatebreakingstrengthand safeworking load of a 3-inch wire ropes. SOLUTION:

3.

= 2x3xJ 2xC2 2.5xC2 = 2.5x3x3 = 18 2C2 6 6

= = =

BS or BS SWL

= l8tons = 22.5tons = 3tons

A wire ropewith a breakingstrainof 13.9tonshasa diametermeasuring: SOLUTION: Circumference =

13.9 2.5

2.5 =

Diameter = 3.1416 4.

2.36 3.1416

=

2.36 inches

=

0.75inch or %"

If your cargorunner is ratedfor a safetyfactorof 5 and the SWL is 10 tons,what size of wire would you use? SOLUTION: BS

= SF x SWL = 5xl0 = 50 tons

=

c ={*

5.

^H

=

^/'=

447"

D = C = 4 . 4 7 = 1 . 4 2 " 3.1416 3.1416 Tbe breakingstrainof a wire rope whosediameteris 1llzinch will be: SOLUTION: = = = = BS

Circum

Dia.x 3.1416 1.5x 3J416 4.71inches 2 . 5 x C 2 = 2 . 5 x 4.71 x 4.71 =

55.5tons

CIIAIN Requiredthe breakingstrength,the proof loadand the working load of a 314inch iron chain. l.

SOLUTION: BS = 30xD PL = l2xDz or

SWL = SWL =

6xD2 8xD2

= = = =

30 x 0.75x 0.75 12 x0.75x0.75 6x0.75x0.75 8x0.75x0.75

= 17 tons = 6.75tons = 3.4 tons = 4.5 ons

Cargo Gears

359

2.

Requiredthe smallestsizeof chain for lifting a load of 5 tons. SOLUTION: DIA. =

.fto - tggL

.E

{iffi-

8

8

=

7/8 inch

8

BRIDLE l.

Youarelifting a weightof 1000lbs.with a twoleggedsling.What is thestresson eachleg if theangle that the legs malcewith eachother is 60o ? SOLUTION: Stress =

=

Weight 2 cosYzQ

= 1000

1000 2 cos30o

=

577lbs.

1.732

You are lifting a weight of 6 tons with a three-leggedsling. What is the stresson eachleg if the angle that eachleg makeswith the weight is 50" ? SOLUTION: Sress =Weight 3 Sin 0

3.

=

6 3 Sin 50"

=

= 6 2.298

2.61tons

Youare lifting a weightof 10 tonswith a four-leggedsling.What is the stresson eachleg if the angle that eachleg makeswith the weight is 4O" ? SOLUTION: Stress = * * = 4Sin0

l0

=

4 Sin 40"

10 2.57

=

3.89tons

PURCTIASB 1.

Whena weightof 800lbs. is suspende4what is the stresson thehaulingpart whenusinga gun tackle roveto leastadvantage? SOLUTION: FORCE Note:

= Weight MA

=

800

= 400 lbs.

Weiglttis suspended. No friction involved.

What is the sfresson the hauling part when lifting a weight of 1000lbs.usinga luffprrchase roveto advantage? SOLUTION: FORCE

= W ( 1 + 1 0 % N o . S h e a v e s )= MA

1000(1+0.3) = 1300=

325lbs

What is the stresson thehaulingpart whenlifting a weightof 1500Ibs.usinga watchtackleor handy billy rove to lqNt advantage? SOLUTION: FORCE = W ( 1 + 1 0 % N o . S h e a v e s =) = 1 9 5 0= 6 5 0 l b s .

M

36,0

A Cargo Gears

1lq0(1+0.3) 3

J

4.

nyo-foldpurchasewith a strainon the haulingpart of 250lbs. if the {/pdld;&n;ga What weightcanbo li,'Ag"N'gBl) t4* = ro-"{ tunvrf le tackle is rove to SOLUTION: 250x 4 = 1000 =714.31bs. ,.O -1.4 aa strginon the hauling What weight canbe lifted using a three-foldpurchaserove td,irdv4ntagg4vith WEIGHT =

5.

=

ForcexMA | + 10VoNo. Sheaves

Soolbs'? Partof

= r\ts'df il't'tuss#

ffi

SOLUTION:

WEIGHT = 6.

Force x MA | + l0% No.Sheaves

5 0 0 x 7 = 3500 = 2187.5lbs.

=

L6

1.6

What is the sgq9s.anl$e{auling part when lifting a weight of 750 lbs. using a doubleluff purchase rovetoleas(advantage?, , | / r

----

sol[mo;-

r 'n (t.oalw*httYq

FoRCE=@

?grftt (tar*rLgr;t

MA = 750(1+0.5) = ll25 5 5 7.

= 225lbs.

A weight of 12 tons is giingliftdqlth a three-foldpirrchase.Find the total load and the pull on the hauling part if useOtoQisaAvanta,g, V(A " ho ..[ JIWS tl t---l

SOLUTION:

n = 6

= 6 W = l.2tons nW S x P = W + -10P

Answer:

8.

=

Sx6

=

12 + 6xl2 10

s

=

19.2 = 3.2 tons 6

I-oad Pull

12+72 = 10

1 9 . 2t o n s

= 19.2tons 3.2 tons

A weight of 30 tons is o be lifted with a three-foldpurchaseusedto advantagewith a leadblock at the derrick end and anotherat the masthead.Find the sEess. SOLUTION: FORCE

= Weight ( I + 10%No. of Sheaves) MA

= l0(1+0.8) = 30x1.8 =

54 = 7.71tons

I

Cargo Gears

36r

9.

A weightof 14tonsis to be lifted with a three-foldpurchaseroveto advantage. Find the tensionon the hauling part of the fall and the sizeof Manila rope to use.Thereis a leadblock at the masthead. Answer:

Stress= 3.4 tons

Circumferenceof rope = 4.gg inthes

SOLUTION: FORCE

=

Weight (l + llVo No. of Sheaves) MA

=

14 (l + 0.7) = 14 x 1.7 = 7 7

23.8 = 3.4tons 7

.f7 x had

=

CIRCUMFERENCE =

SINGLE WHIP

=

^n fiA

4.E8inches

GUN LUFF TWO FOLD DOUBLE THREEFOLD TACKLE TACKLE PURCHASE LUFF PURCHASE

(TtrfrMMM ( ? ' ? * Y * ? r\ |

frfrddfrtr MAI

MA2

MA3

MA4

MA5

NOTB: ALL RIGGEDTO DISADVANIAGE

x2

Cargo Gears

MA6

PRODUCTS GRADESOF PETROLEUM GRADE

POINT FLASH

REIDVAPOR PRESSURE

EXAMPLES

A (Flammable)

80"F or below

14psior above

naluralgasoline, verylighlnaphthas

B (Flammable)

80"F or below

morelhan 8.5psibttt lessthan 14 psi

mostcommercial gasolines

C (Flammable)

800F or below

8.5psior below

mo$ crudeoils, aviation creosote, gas,iettuel

D (Combudible)

above80"F butbelow 150'F

kerosene, someheavycrudes, commercial iet fuels

E (Combustible)

150"F or above

heavyfueloils, oils, lubricating asphalt

FLAMMABLELIQUIDSarethosewhichgiveoffflammablevaporsatorbelow80"F.Thesearefurth subdividedintogradesA,BandConthebasisoftheirReidVaporPressure. above80" F give offflammablevaporat temperatures COMBUSTIBLE LIQUIDS are thosewhich givesoff sufficientvaporsto flashacross a substance FLASII POINT is the lowesttemperatureat which the surfacewhen a flame is aPPlied' will give off sufrrcientvapor to continueto a substance FIRE poINT is the lowesttemperatureat which burn when ignited. ignite. will sponraneousry ar which a substance TGNITT'N TEM*ERATURE is the lowesttemperature ExPLoSIvERANGEoRFLAMMABLELIMITS.Hydrocarbonvaporswillnotburninanatmospercentthe vaporsmuJtfall within a givenvolumetric pherecontainingless ianloz"oxygen. In addition, (seethe burn not will vapor little containingtoo much oi too ageor no reactioncan takeplace.A mixture tableon the next Page).

Cargo Handling and StowaSe

363

FLAMMABLE LIMITS (Percent byVolume inAir) PRODUCT

LOWER LIMIT

CrudeOib (average)

1.0

10.0

Gasoline

1.3

t.6

Kerosene

0.7

6.0

Propane

2.1

9.5

Methane

5.0 1.4

15.0

1.4 2.0

/.o

Benzene jet tuel) JP4(military Ethylene oxide

When vapors are present in amounts above the upper flammable limit, the mixture is said to be roo rich to burn. If below the lower limit, it is too lean. SPECIFIC GRAVITY is the densiryof liquid relative to the density of water. When the specific gravity of an oil is known and also the temperature of the oil, it is possible to work out thrweight of a given volume or the amount of spacea weight of oil will need. The specific gravify is of little or no use without the temperature of ttre oil. VAPOR PRESSURE Petroleum products vary considerably in their ability to give off gas or vapor, but generally those with low flash points produce the largest amount of gas. Their ability to give off gas depends to a very large degree on temperatue. In a given size container or tank, the same petroleum product will give off more vapor at a higher temperature than a lower. If the surfaceof the liquid petroleum is agitated, this can help to increase the amount of vapor given off. VISCOSI'IY is the internal resistancea liquid has to flow. The viscosityof a liquid is not constantbut may change considerably with an increase or a decreasein temperature. Thicker oils, which are heavy and sluggish when in motion, may be quoted in thousandsof seconds,and are said to have a hish viscosity. DEFINITION

OF TERMS:

Bale capacity. T'he cubic capacity of a spacewhen

364

UPPERLIMIT

8.0 100.0

the breadth is taken from the inside ofthe cargo bat_ tens, the depth from the wood ceiling to the underside of the deck beamsand the length from the in_ side of the bulkheadstiffenersor sparring where fitted. Grain capacitl'. The cubic capacitvof a spacewhen the lengths, breadthsand depths are taken right to the plating, An allowance is made for the volume occupied by frames and beams. Stowage factor. The volume occupiedby unit weight ofcargo. Usually expressedas cubic meters per tonne or cubic feet per ton. It does not take into accounr any spacewhich may be lost due to broken stowage. Broken stowage. The spacebetweenpackageswhich remains unfilled. The percentagethat has to be allowed varies with the t1'peof cargo and with the shape of the hold. It is greatestwhen large caseshave to be stowedin an end hold. Deadweight cargo. Cargo on which freight is usually chargedon its weight. Cargo stowing at lessthan 40 cu.ft. per ton is likely to be rated as deadweisht cargo. Measurement cargo. Cargo on which freight is usually charged on the volume occupied by the cargo.Thiscargo is usually light, bulky ca_rgo stowing at more than 40 cu.ft. per ton. Ullage. The vertical distance from an above deckdatum (usually the top ofthe ullage hole) to the surface of the liquid in the tank.

Cargo Handling and Stowage

all of which are affectedby the humidity of the atmosphereattracting, reaining and giving of moisture (water vapor). Hygroscopiccargoescauseship Ihlefage. The lossof liquid not definitely accounted sweatby vir&e of changesin temperature,particufor, as by leakageor evaPoration. lady whenpassingfrom warmloadingareasto cooler Tblevlng. The processof determining the anount onditions. of waterpresentin a tank filled with oil cargo. Non-hygroacopic cargoes. Consist of materials of fopptng ofi. The act of regulating the valveswhen solidnaturesuchassteelproducts,machinery earthloading throug[ship's lines in completing the level enware, cannedgoods and the like, which can be subjectedto damagefrom cargo sweatand condento which a ta*,ot tanks are to be filled. rusting, staining, or discoloraproducedin sationin the forrr of Spontaneouscodusdon. C-ombustion tion. tlappens when loading has takenplace in cold aiubsrance througfogenerationof heatby chemical climates and the cargo later subjectedto wann cliaction of its ovn constituentsand/or by absorption matic conditions. of oxygenin tbe'heating Prccess. Inherent vlce. The natural tendencyof someparAd vabrcm cargo. Goodscanied at a freight ratp ticular goodso be wastedor becomedamaged,as, accordingto their value. for instance,spontaneousheating ofoopra or hemp, Dew polnt. The lowesttemperatureto which air can black rot in apples,diseaseof livestock, fennentabe cooled without condensationof its water vapor. tion of liquid and the like. Shouldtemperaturefall belowthis point, dewor frost Talnt damage.Danage to goodsdue to other cargo may fonn. having been wetled by seawater in heavy weather

rnnege. The soundingor measureddeptb of liquid, 25 ia 4 tank.

tlygrmcoplc cargo. Mainly of vegeubleorigin such as grain, flour, coson, tobacco,wood and the like,

or dueto contactwith other cargoor causedby odors from other cargostowedin the samehold.

TIIE RULES OF IIOLD VENTILATION 1. If the dew point outsideis lower or equalto thatof the hold dew point ... continueventilation. 2. If the dewpoint outsideis higher than the hold dewpoint ... do not ventilatewith outsideair.

(hygroscopicand non-hygroscopic),then a further extensionof thebasicrule canbe made.Any voyage will involve one or more stagesduring which the outsideair and the seatemperatureswill either progtessivelyriseor fall, or wherethereis little change.

Considering the trvo basic categoriesof cargo Hygroscoplc Cargo

Non-hygrocoplc Gargo

Coldto wam voyage

On openingof hatdtesat destib notessential. Notcrilical.Ventihtion mayforma surlacebut will dry ofr nation,immediatecondensation is disdtarge. whencargo

Wamto cold voyage

shouHbe as vigorousas pssible dudngthe Highlyailical.Ventilation the outsideD.P.will be to low.Thisis the eady$agesbul eventually ventilamo$ difficultvoyagesituationin whidrto anangesatidactory lion.

CoHto wam voyage

cargosureatwouldocculon the surlaceof the stowif No ventilation; ladenair wasadmitled. warmermoislure relatively

Wamto cold voyage

ddps unaffededunlesscondensation but cargr., ShipsweatineMtable backon to the stow.

Cargo Handling and Stowage

36s

SWEAT SWEA'T is condensationwhich fonr:,son all surfacesand on all goodsin a compartmerrtor hold due to theinability of cooledair to hold in suspension as muchwatervapor aswarm air.

3. To provideair passages for the heated,mois ture-ladenair to travelto the sidesandbulk headsalong which it ascendstowardthe up takes.

1. SHIP'S SWEAT is a condensationon the ship's structure.Ship's sweattakesplacewhen the dewpoint in a cargospaceexceedstie temperature of the structuralparts of the ship. It is minimized, or eradicated,by passingadequatevolumesof outsideair over tle cargo,moreparticularlynecessary in a vesselpassingfrom warmto colderafinospheric conditions.

4. To protectit from contact with condensed moisturewhich is collectedand retainedon sidestringers,bulkheadbrackets,etc. 5. To preventchaffageaswellastochocko{f and serure cargoby filling in brokenstow age, i.e. spaceswhich cannotbe filled with cargo.

6. To evenlyspreadout ttrecompression 2. CARGO SWEAT is a condensation directly loadof deepstowages. on the cargo.Cargo sweatcan arise when passing from cold to wanner climatic conditionssincethe SPAR CEILING. Battenslaid in holds and rween causeis from the warmermoistureladen air condecks of shipsother than colliers,tankers,and timdensingon thecargo.Its preventionis by sealingoff ber and orecarriers.Theyare fitted on the sidesfrom the ventilating facilities, although extractionfans the turn of thebilge upward,andare spacedabout9 will be neoessaryto offset any moistureeffectsemain. apart.Their thicknessis about2 in. and width 6 nating from the cargoitself, or its dunnagingmateto 7 in. Theli preventtbe cargo from coming into rials. contactwith the framesor shell plating, with the DLII\NAGE. A tenn appliedto loosewoodor other resultingdamageby moistureor sweat.The boards materialusedin a ship's hold for the protectionof are arrangedverticallyor horizontallyaccordingto thesystemof framingadopted.Also calledsparring, cargo. hold sparring,oper ceiling, opensparring. Dunnagingservesthefollowingpurposes according to the natureof tle cargocarried: MOISTURE IIIGRATION. A phenomenon dueto l. To protectit from contactwith water from transferof moisturethroughthe stowedcargoasthe the bilges, leakagefrom other cargo, from shipproceedson her voyage.The directionandrate of this dependson the vaporpressureof the air at ship'sside or from doublebottomtank. variouspoints in the stow.Freemoisturewill tend 2. To protectit from contactwith moistureor to evaporatein contact with unsaturatedair at or sweatwhich condenseson the ship's sides, nearthesame temperatureandtie rateof evaporation frames,bulkheads,stringers,brackets,andso dependson the relativehumidity of the air and the on, and falls down on thecementcaps,from speedat which it passes over the cargosurface. whereit finds its way into the bilges.

DANGEROUS GOODS The InternationalConventionon the Safetyof Instrument1965No. 1067,lnown astle Merchant Life at Seaheld in 1960maderecommendations for Shipping(Dangerous GooG) Rules1965,ro bring the classificationand labellingof dan3erousgoods. them into force. The new pnovisionsbecameeffecti.'con 26th May The StatutoryInstrumentdealswith the descrip1965,and the United Kingdom issueda Statutory

366

Cargo Handling and Stowage

tion,marking,packing,stowageandcarriageof dan- CLASS 5(b) OrganicPeroxides; gerousgmds. It also lists the various explosives CLASS6(a) Poisonous(toxic) substances; which are permitted to be taken aboardand carried shiPs. CLASS6O) Infectioussubstances; on passenger The shipperof the dangerousgoodsmust give the owner or master a certificate in writing to the effect tlat the shipment is properly marked. The minter of the ship is responsiblefor the provisionof thelist, manifestor slowageplan to be carriedin the ship showingthe dangerousgoodscarriedand their stowage.

CLASS7

Radioactivesubstances;

CLASS8

Corrosives

CLASS9

Miscellaneousdangeroussubstances; that is any other substancewhich experiencehas shown,or may show,[o be of sucha dangerouscharacterthat tlte dangerousgoodsrules shouldap-

All dangerousgoodsmustbe clearlymarkedand PIY; the labelsare in accordanceivith the recommendations of the InternationalConvention.They corre- CLASS 10 Dangerouschemicalsin limited quanspondwith the following classification: tities. CLASSI

ExPlosives;

CLASS 2

Gases:compressed,liquefied or dissolvedunderPressure;

COMMERCIAL EXPLOSIVESaredividedinto the following classes: CLASS I

GunPowder

CLASS II

Nitrate mixture

CLASS4(a) Inflammablesolids;

CLASSIII

Nitro comPound

liable CLASS 4O) Infiammablesolidsor substances combustion; to spontaneous

CLASSIV

Chloratemixture

CLASS 3

Inflammableliquids;

Fulminate CLASSV CLASS4(c) Inflammable solids or substances which in contactwith water emit in- CLASSVI Ammnunition flammablegases; CLASSVII Firework CLASS5(a) Oxidizingsubstances;

Cargo Handling and Stowage

367

DANGEROUS GOODS LABELS

/ , ^/ ( -\ \

,/D,\

f7

^*GLtu y

soI-n

,zz

\ r r l

RADIOACTWE

RADIOACTTVE

368

a

RADIOACTWE

Cargo Handling and Stowage

CARGO HANDLING AND STOWAGE 1. Cargoes that have the capability of absorbing moisture are called: c. Inherent vice b. Contaminated o. Hygroscopic

d' Tainted

2. What is the flash point of liquid classified as Grade E? c.l50"Fbelow b.l50"Fabove a.80"Fbelow

d.80'Fto150"F

3. When coming from cold climate to hot climate and carrying hygroscopic cargo, you should: a. Not ventilate. D. Ventilate continuouslY. c. Ventilate only to raise the dew point. d. Ventilate only when cargo temperature is warmer than the dew point. 4. The most important factor to determine the good turnout of refrigerated cargo is: c. Temperature maintained rr. Cleanliness of space Good stowage d. ,. Good ventilation 5. The most inherent danger in LPG is: a. l-nw temperature causesfrostbite or freezing. b. Reacts to sea water. c. Strong odor is Produced. d. When warm becomes heavier than air. 6. Which of the following best indicates how many lons of cargo a vesselcan carry? c. l,oaded displacement a. Bale cubic d. Gross tonnage b. Deadweight 7. Corrosive liquids would have what kind of label? c' White a. Yellow d. Red b. Skull and cross-bones 8. The permanent dunnage attached to the frames of the ship that aids in ventilation is/are the: d. Sweat batterrs c. Hatch beams b. Tank top a. Hatch boards 9. Common deficiencies in laying dunnage is/are: c. Improper spacing. a. Best drainage is not provided. d. All of the above b. Insufficient tiers. 10. Cargo damaged due to water being present in a cargo hold, as a result of a leak in the hull plating is said to be damaged bY: c. Both a and b a. Freemoisture Neither a nor b d' moisture b. Transfer of hygroscopic 11. The term used to denotea quality of changein some cargo which damagesthe commodity itself is: d. Inherent vice c. Deterioration b. Tainting a. A latent defect 12. Cargo which has a stowage factor of 40 is termed: c. Advaloremcargo a. Deadweightcargo d. Insured cargo b. Measurement cargo 13. Protection of cargo against tainting damage can be best obtained by: c. Proper use ofpaper separation and dunnage. a. ventilating the space. d. Segregationofcargoby using different hatches' b. Not ventilating the space.

Cargo Handling and Stowage

369

14. The ratio of the amountof watervaporactuallyin the air to the amountthat woutdbe in the air if the air is saturatedis: a. Relativehumidity b. Absolutehumidity c. Dew point d. Specific humidity 15. The temperaturebelowwhich the air will be unableto retain the moistureit presentlycontainsis: a. Dry bulb temp. b. Dew point c. Wetbulb temp. d. Wetbulb depression 16. Which of the following iVare correct? a. Ventilationhasthe singleobjectiveof preventingdamageto cargothat originatesfrom condensation within the cargoholds. b. The dew point temperatureis dependentonly upon the moisturecontentof the air. c. Both a and b d. Neithera nor b 17. A spacashouldbe ventilatedwhen: a. The cargotemperatureis colderthan the dewpoint of the air in the space. b. Tbe cargotemperatureis warmertlan the dewpoint of air in the space. c. The dew point of the air in the spaceis higher than dewpoint of the outsideair. d. All of the above 18. The dew point of the air in tle ship'shold is to: a. Be kept below the tempenrtureof the cargoto preventcargosweat. b. Be kept abovethe temperatureof the hull andbulkheadsto preventship's sweat. c. BotI a and b d. Neithera nor b 19. The properstowageof refrigeratedcargoincludesattentionto: a. Humidity control c. Both a andb b. Air circulation around the cargo d. Neithera nor b

I

20.Which of the following is most importantin the preventionof sweatdamageto ciugo in.tn\notAt a. Outsidetemperature b. Dewpoint of the air in the cargo hold

c. Dewpointof the outsideair d. Temperatureof the cargo

21.Dry bulb temperatureis 68 "F. Wet bulb temperatureis 61.5 "F. The relativehumidity is: a. 68Vo

b. 69%

22. Which of the following iVare correct? a. Frozencargois 12 "F to 20 "F b. Chilled cargois 28 "F CI40 "F

c. 70Vo

\ \

d. 7l9o

c. Air cooled cargo is 42 "F to 55 "F d. All of tle above

2 3 .Sweatdamagewill occurin a cargohold containingmachinerypartswhen: a. b. c. d.

The outsideair is coldertian tle cargo. The air temperatureof the hold is higher than theoutsideair. The dew point of the hold is higherthan the temperatureof the cargo. The dew point of the outsideair is lower than the temperatureof the cargo.

24. When loadingdifferentcargoesthroughthe samepipelineyou shoulddetenninewhich cargoto load first except: a. Flash point

b. Specific gravity

c. Trim, hog and sag d. Cleanlinesofcunmodity

25. How could you compare the weight of LPG vapor with air?

a. Lighter

370

D. Variable

c. Heavier

Cargo Handling and Stowage

d. The same

26. What is the tendencyof gasolinefumes? a. Settle on the level of the bilgeby mixing with air. b. Disperseto amosphere. c. Settlenear the top of the bilge. d. Settlenear the bottom of the bilge. Tl . Wby doesLFG gascarrier not requiredto havegasfteeing? a. LN content makesit non-volatile. c. Cargo tanks are inspectedlessfrequently. d Cargoanks are purged of water and air. D. Regulationdoesnot require. 28. The necessityof ventilating the bilge is o: c. Provide adequateair to the engine. D. To cool the machineU !ea"

c. 1lodry the bilge for cleaning. d. Re,movefuel vapor which is heavier than air.

29. Ttre mostjmportant factor to considerwhether to ventilate or not a cargospaceis: b. Dry bulb temp. c. Wet bulb temp. d. Rela,tivehumidity a. Dew point 30. The normal percentageof oxygen in air is: b. 18% a. 2l%

c. 16%

d.25%

31. A temperatureat which a liquid nust be hearedin order to give off flammablevapor is: c. Fire point b. Explosiverange d. Noneof these a. Flashpoint 32. Long ton is equalto: a. 10001bs.

b. 20001bs.

33. GradeA peroleum productis: a. A combustibleliquid D. Jet tuel

c. ?.2;0lbs.

i'

d. Z00lbs.

/ c. Lubricatfuf oil d. A fianntble liquid

34. Liquid cargo loadedor dischargedin volume alwaysstatesp standardtemperatureof: ,. 50 "F c. 78 "F ' d. 72"F a. 60 "F 35. Greenlabel cargo indicates: a. Explosives b. Corrosiveliquids

c. Non-flanfrableompressedgas ''.---d. Poison

36. A petroleumliquid witb a flash point of 83 T would be: c. FlammablegradeA a. CombustiblegradeE d. Flamnable gradeB D. CombustiblegradeD 37. T\e advantageof a containervesselover a conventionalfteighter is all but: c. Quick turn around a. Flexibility d. Quicker to load and discharge D. Savesstevedore'sfee 38. The lowesttemperaturerequiredto causeself-sustainedcombustionof a substanceindependentof any outsidesourceofignition is: c. Ignition temperature a. Explosive range d. Combustiontemperature D. Flash point . 39. Which of the following is the main purposeof ventilating holds with cargo? c. Both a and b a. To prreventair condensation d. Noneof these D. To prreventgasaccumulation

Cargo Handling and Stowage

371

-rr

40. Whencarryingbulk grains,what shouldyou observeto minimize cargoshifting effects? u. Inave somecompartmentpartially full. b. lnvelall grainsfree surface. c. Leaveat leasthalf of cargor ompartmentpartially full. d

Pump out all ballasts.

41. Hygroscopic cargo is defined as: a. Cargo in a liquid state.

c. Capableofgivingofmoisnrein theforrr of liquid. b. Cargoignitingwhenincontactwithwater.d. Capableofabsorbingmoistureintheformofgas.

42. Which of the following operationsmay causethe pressurein an inertedtank to fall belowprescribed limit? c. Steamingtanks d. l-oading a. Crudeoil washing D. Discharging 43. The main advantageof tle use of unitized cargo systemsuch as preslinging,palletization,or contarnenzauonrs: c. Costreductionin termsof cargooperation a. Cleaneroperation Noneof these at sea d. of cargo Avoid shifting D. 44. A petroleumliquid is said to be a GradeD combustibleliquid when its flash point is: c. Above80 "F but below 150 "F a. Irss than 80 "F "F d. Above80 "F ,. 80 or below 45. Which of the following valvesoffer the leastresistanceto flow whenfully opened? a. Butterflyvalve

D. Gatevalve

c. Relief valve

d. Non-return/valve

46. When a tankeris partially loaded,gasformationin the cargotanksis dueto: area c. Draft b. Compressed a. Surfacearea 47. The primary hazardsin transportingLPG and LNG is: c. Temperature b. Toxicity a. Pressure

d. Flammabili

48. Which of the following is strictly forbiddenwhen handlingbaggedcargoes? d. Hooks c. Ropeslings D. Strapsor slings a. Storagenets of loading,whatprecaution 49. Oncea bulk carrierfloodhold hasbeenpumpedoutprior to commencement shouldbe taken? a. Floodholdshouldnotbe loaded. b. No specialprecarrtionis needed. c. Propedycoverall wells to protectboth ballastandpumpingsystem. d. Removeflangeswhich shouldbe installedin the next discharging. 50. A flammableliquid is any liquid that givesoff flammablevaporsat or belowa temperatureof: d. zlZ"F c. 100"F ,. 80 "F a. 60 "F 51. The tendencyof a flammableliquid to vaporizeis indicatedby its: c. Convectionindex a. Flash point d. Flammablerange b. Ignitiontemperature 52. Damageto cargocausedby fu.nesor vaporfrom liquid, gasesor solid is called: d. Contamination c. Oxidation b. Vaporization c. Tainting

372

Cargo Handling and Stowage

you do? 53. Whena pump during dischargingoperationis cavitating,what should a. Shutdown the PumP. b. Closedown the valve locatedon the dischargeline' c. Openall valveslocatedin the cargoline. cargocan bedescribedas: 54. A heterogeneous cargo a. General b. A mixture of cargoeswith dilferentdensities c. Either a or b d. Neithera nor b heavypiecesaboardship? 55. What specificconsiderationshouldbe takeninto accountwhenstowing points. a. The availabilityof lashing b. Theresistanceof the hold deck,nveendeckor deck' c. Both i and b d. Neithera nor b 56. By regulation.a cargotank mustbe inertedbeforeand during what operation? d. Crudeoil washing c. cleaning b. Stripping a. t-oating 57. If the hold's air dew point is higher than the outsideair dew point: a. Ventilationwill contaminatethe cargo' b Holdsmaybeventilatedas thereis no risk of condensation' c. Holdsshouldnot be ventilatedas thereis condensqtion' d. None of these 58. Safetyis increasedif: a. Extra line and wire are laid on deckfor emergency' b. Powertools are kept plug for immediateuse' c. Spareparts are kept on deck for readyaccess' ''' d. Nl lashingsaremadeup and the deckis cleanand clear' 59. Tankersshouldcarry cargohosethat can withstanda pressureof at least: d' 150Psi c' 75 Psi b' 120Psi a. 100psi 60. Cargoesthat are susceptibleto leak from containersare: c' Causticcargo b. Dirty cargo a. Wet cargo

d' Bulk cargo

aboardbe stowed? 61. Whereshouldcargoeswhich by their naturecould contaminateothercargoes dunnage' by other each from a. In the samehold but separated by a drainage' D. In the samehold compartrnentbut separated commonventilation' a not sharing c. In a separatehold compartment air ventilation. with constant and d. In the iame hold comparfrient 62. The following productsare volatile except: b. Heavyfuel oil a. Benzene

c' Coal tar

r/' Diescl lurl

point o1tite air in lhe crgo 63. When the dew point of the outsideair is lower than or equalto the dew hol4 you should: c' Secureall ve;rtilation' a. Shutdown the intakeblowers. d. shut down exhausthkrwcrs. b. ventilatecargoholds.

Cargo Handling and Stovugr

373

64. What is the advantageof transportinggasunder refrigeratim? c. It increasesits volume. a. [.essproductper volume. Itfrgozrs while in transit. d. its volume. reduces b. It 65. Which of the following is classifiedas a combustibleliquid? c. Acetaldehyde a. Ethyl alcohol d. Carbontetrachloride b. Tetraethylineglycol 66. Dunnageprimary useis to protect cargo from damagedue to: c. T[inting a. Hygroscopicabsorption d. Ship'ssweat Inherentvice b. 67. In accidentalpollution, the mostcritical time during bunkeringis when: c. Final topping off is occurring. a. You first start to receivethe fuel. d. Hces arebeingblown. b. Hodesare being disconnected. "F "F? 68. What will happenif the flash point of kerosenewhich is 100 be heatedabove110 c. Boil off to atmosphere. a. Burn and explode. Nothing. d. handle. to easier volatile and b. I-ess 69. An inert gassysteminstalledon tankersis designedfor: a. L.oweroxygenlevel insidethe cargotanksmaking explosionremote, b. Nd in sripping and cleaningof tanks. c. Forcetoxic and explosivefumes from a cargo tank' d. Increaserate ofdischarge. "SPECIALIARGO"? 70. What is a gaswhenheated. c. It hasa high value that pilferageis tempting. a. Cargothat givesOfiRlQxic while on board. d. It mustbe stowedon deck. is requibd Periodic check b.

l

71. The effectof a heatedbulkheadon a hygroscopiccommodityis: c. Raisevapor pressureof the commodity. b. Lovrervapor pressureof the commodity' c. Causemoistureto accumulateagainstthebulkhead. d. Lnwer the dew point. 72. ^Black powder" would be classified as: b. Corrosive a. ExplosiveA

c. ExplosiveB

I

d. ExplosiveC

73. "Anhydrousarnmonia"would havewhat label? c. Corrosive a. Non-inflanmable gas d. Greengas D. Yellow 74. Nlullage holeson a tanker'scargotanksare requiredto be fitted with: c. Pressurereliefvalves a. Approvedflane screens relief valves Pressure-vacuum d. b. Approvedflame arreston 75. A hoseis found tobe lealdngwhile loadingliquid cargo.You stopcargooperations.Whatmust be done frst in order to resume&e cargooperations? c. Replacethe hose. a. Patchthe hose. d. Reducethe speedof the cargopumps. b. Notify the dock.

374

Cargo Handling and Stowage

the ship officer in-chargeshouldseeto

76.During loading/unloadingand stowing/breakbulk operations, it that the cargo is being handledfollowing: o. 1.n" orderi receivedftom the shipper. D. The directions issuedby himself.

c. The ordersfrom the ca'go recerver' d. T\e ordersfrom the stevedores'

has beencausedby the failure of the ship 77.The shipowneris subjectedto claim if the cargo damage officer to: lat€nt defecton cargo a. Ensuretle fitness and safetyof cargospace c. Detect these of None d' b. Ensureadequatepackaging must seethat all hatch coveringsare: 78. When work is finished for the day,the cargoofficer d' All of the above Secured c' D. Water tight a. In place 79. Usedto classify cargofor speedydischarge' D. Portmarks a. Forklift

c. Cargonrrtbers

grain hatch from reachingan angleof repose? 80. what equipmentusedto Fevent grain in a slack Ipvel dunnagewith compatiblecargo c. a. Leveldunnagewith wire straps d' Side batten b. Shifting boards cargoby running the timber from an upper supportdown to the 81. The processof using timbers to secrure cargoeither vertically or at an angle is called: d' Pracing c' Dunnaging D. Shoring a. Tomming for: 82. An inert gas systeminstalled on tankersis designed tank' a. Forceioxic and explosivefumes from a cargo b. Increasingrate ofdischarge c. Aid in striPPing of tanks free. d. Lwtqoxygen ievel inside cargo tanks making them explosion 83. Usedfor baggedgoodsin preferenceto rope slings: c' Cargonets D. Wire slings a. Canvassslings

d. Conveyor

productsloadedin bulk will retain their forrt 84. The maximum angle at which grain, oal o'r other remain in a heaP. c' Angle of list o. Angle of inclination d' Angle of repose b. Angb of trim 85. A gasor mixture of gasesincapableof supportingcombustion' c' Fumes b. GasvaPor a. Inert gas

or

d. Oxygen

from ship to shore' 86. The connectionof metal plates to ensureelecrical continuity d' Alloftheabove Charging c' D. Bonding a. Welding g7. The processof replacing foul air in any of the ship's conpartnent with pure air' d' Purtffing c' Refrigerating b. Ventilating a. hrrging explosivesare classifiedas: 88. Under International Maritirre DangerousGoodscode, 3 Class c' b. Class2 a. ClassI 89. One barrel is equivalenl to: "F a. 42lJS gallons at 60 "F a. nOUS gallonsat50

"F c. 43 US gallons at 65 "F d. 45 US gallons at 75

CargoHandling and Stowage

375

90. Which of the following is a wet cargo? a. A cannedor bottled liquid suchasbeer b. A cargothat containshygroscopicmoisture c. A cargo particularly susceptibleto danage by moisture d. A liquid cargo in the deeptanks 91. If you are bunkering and pu closeoff one rqnk in the line of tanksbeing filled, the rate of flow to the otheropentankson the sameline will: D. Stop c. Increase d. Remainconstant a. Decrease 92. Ullages on tankersare measuredfron the: D. Abovedeckdatum c. Thievagemark a. Bushing

d. Tankceiling

"thieving" a petroleumcargo? 93. What is meantby a. Reducingthe grosscargocalculationsto net amounts. b. Siphoningoff a few barrelsof petroleumcargofm shipboarduse. c. Adjustingthe cargofiguresto coincidewith the draft. d. Deterrrining the amountof water (if any) in eachcargotank. '

94. Oil productsamplesshouldbe takenfrom the: c. Shoretank discharee a. Dock riser d. All of these D. Ship's cargotanks 95. The flammablelimits for motor gasolineare: a. 1.4%to 7.6%mixturein air b. 5.09oto 7.0% mixture in air

c. 2.5Voto 9.87omixturein air d. 0.9Voto 5.9Vomixture in air

96. BunkerC and fuel oils areknown as: b. Slopoils a. Solubleoils

(

Cutting oils

d. Viscousoils

97. The water which accumulatesat the tank bottonrciir the form of leftoverballast,tank washingsand condensationis measuredby the processof: r'. Lllaging b. Sounding a. Thieving d. Dipping 98. The standardtemperaturefrom which to calculat.:tho net amountof oil in a tank is at: c.60"F c.32"F a.45"F d.15"F 99. Spills are causedby: c. Brokenhose

D. Improperline-up

c. Gravitation

d. A-lloftheabove

100. The vertical distancemeasuredfrom the tank bottomto the liquid surfaceis called: b. Ullage c. Thiefage d. Thievage a. Innage 101. A centrifugalpumpmustbe primedto: a. Overcomepressureof water in the dischargeline b. Lubricatethe shaftseals c. Ltftwater level to impellers d. Make the pressureequalto dischargepressure 102. Whenballastingthroughthe cargosystem,the main objectiveis to preventoil in the line from escaping.The frst thing to do is to: c. Openthe tank valves a. Start the pump d. Artyof the above b. Open the seavalves

376

Cargo Handling and Stowage

103. Beginswhen the tank is about60% empty. D' Middle wash a. Bottom wash

c. Top wash

i04. negins when the tank is almost completelyempty' c. Middle wash b. Bottgmwash a. Top wash

d. Deck wash d. Deckwash

105. when seawateris pumped into cargo tanks, it inevitably washesoil from the tank surfaces.The resultantoil-watermixture is called: d. Oil-water ballast c. Oily ballast D. Ballastwater a. Dirty ballast 106. which statementis correctregardingsegregatedBallastTanls? a. Oil cargo are separatedfrom ballast by using different pumps' b. Ballast and oil are loadedinto different tanks. c. Ballast tanks incorporatea complet€lyseparatesystemof pumpsand pipelines for clean ballast d. Nonenf tbese 107. It is condensationwhich fonns on all surfacesand on all goodsin comparEnentor hold due to the inability of cml air to hold in suspensionas much water vapor as wann air. d' HumiditY c. Dew b. EddY a. Sweat l0g. During discharging,it is very importantto preventc:rgo from falling directlyinto the waterby using: d' Pallets c' Cargonet b. Wire sling a. Ropesling 109. Brokenstowagemeans: b. Irst in sPaoe a. loss of cargo

c; Damageto cargo

d . All of the above

dunnage,occupies ll0 . The numberof cubic feetwhich one ton (22,+0lbs.) of goods,with the necessary in the shiP'scargospace. d. Deadweightcapacity c. Cubic capaqity D. Broken stowage a. Stowagefactor 111. Which of the following is/arethe source/sof moisturein the air of a cargohold? "sweat" c. Spontaneousheating of certain goods a. Condensationor All of the above d. ofwetcargo D. Presence Ll2. Thevolumeof bulk grain which fills cargospacein question,expressedin cubicfeet' d. DeadweightcaPacitY c. Grain cubic a. Measurementton D. Bale cubic 113. A volumeunit of 40 cu. ft. usedin computingfreight charges' c' Registeredton a. Measurementton b. Deadweightton

d. Net ton

114. The volume of a full load of balesor casesin a given comparonent'as measuredinside the sPar ceiling. d. Deadweightton c. Balecubic b. Measurementton a. Grain cubic 115. The tenn in marking shippingoontainerswhich meansweightof containeronly' d' None of these c' Net b. Gross a. Tarc 116. The term usedin marking shippingcontainerswhich meanstotal weight of containerand contents. d. Deadweight c. Tareweight b. Net weight a. Grossweight I I 7. The tenn usedin marking shippingcontainerswhich meansweight of oontentsonly. d' Any of the above c. Tare D. Net a. Gross

Cargo Handling and Stowage

377

U8. What s3owagemust be providedfor fibers of animal or vegetableorigin that havebeeninvolved in a ftre or that havebeenwet? c' Engine room stowage a lnvter hold stowage d Deck s0os'age D. Theen deck stowage 119. All of the following are the usesof dunnagsEXCEPT: a. To protect cargo from contact with leakagefrout other gmds. b. To preventchaffing by chocking offfrom stanchions,web franes, etc. c. Gives additional freight to the shipowner. d. To provide air coursesin the necessaryventilation ofcargo' 120. The act of regulating Oe valves when loading througb the ship's lines in completing the level to which a tank or tanks are to be filled' d. Dipping c' Thieving b. Topping off a. Stripping l2l. ln connectingcargo hose,what is the minimrrm numberof bolts pemritted at a flangedjoint? d' Five c. Four b. Tlvo a. Three lZ2. In rigging a wind sail to ventilate qil tanks after cleaning operation,wherewould you placethe lower end of the canvassduct? c. At the middle of the tank a. At the top of the tank d. On deck D. At the bottom of the tank 123. T\e loss of liquid not definitely accountedfor, asby leakageor evaporation. d. Innage c. Ullqge D. Thievage a. Thiefage 124. FWt should Oe ullage hole in an oil tank be protectedwhen the tank is open and not gasfree? c. With canvasscover d. With flane screen With plastic cover plywood d. b. By overing with 125. Goodshaving a stowagefactor of 40 or less. a. Advaloremcargo b. Weight cargo

c. Measurementcargo d. Sowage cargo

126. Goodsstowingat more than 40 cu. ft. per long ton. c. Measurementcargo a. Weight cargo d. Sowage cargo D. Ad valorem cargo 127. Cioodscarried at a freight rate accordingto their value. c. Stowagecargo a. Ad valoremcargo d. Measurementcargo b. Weight cargo 128. All of the following are necessaryconditions that must be maintainedin a refrigeratedcomparErent in order to have a good cargotulllout EXCEPT: c. Properstowage a. Cleanlinessof cargosprce d. Constantrefrigeration b. I,,clutrelative hrmridity 129. T\eterm usedto describeoils suchasalmond, attar of roses,clove, wintergreen,liavande4etc., which are usedin perfumery and cooking. d. Cmking oil c. Vegetableoil D. Essentialoils a. Petroleumoils 130. A skull and crossboneslabel indicateswhat type of dangerouscargo? c' Flarunableliquid a. Poisonorpoisonousgas d. Oxidizing agents D. Corrosives

37t

Cargo Handling and Stowage

FORMULAS CubicCapacitY Weight in I-ong Tons

StowageFactor

v -v

96Broken Sowage

x roo

V

V v

= =

Total Volume Volumcoccupiedby cargo loaded

Cu. Capacity- (CargoWt. x Small SF) Difference in StowageFactor

WT. of Large SF

L ' x W ' x H ' x 1 2

Board Feet

Board feet l2

Volume of Lumber

DeckLoad x StowageFactor 2240

Maximumlleight

Deck load in lbs'/fi' StowageFactor in ff/ton Net Barrels @ 60" F

=

Gross t I Gross x Coef. x (Diff in Temp' fiom 60" F)]

Coefficient

=

Coefficient of Expansion or Contraction

Net Barrels @ 60" F

=

GrossBarrels x m factor

m Factor is multiplier from API Table6A or 68 Total permissible to Load

=

Coef' atHigh TemP. x Max' Volume Coef. at Inw TemP.

CargoAssessments

379

SAMPI,E PROBLEI\I.S: 1.

A cargohold measures65' long, 28' wide and 17' 09" high. A cargoonsisting of 600 cases,each measuring5' x 4' x 2'06" is tc be loaded.Allowing a brokenstowageof 5%,how much space, if any, will therebe remainingin the _'-old? SOLUTION : = = = = =

Vol.ofHold Vol. of Cases Vol.of Hold 30,000/0.95 Remaining space 2.

65'x 28'x 17.75, = 5' x 4' x 2.5' x 600 = 32,305cu.ft. - 31.579cu.ft. 72,6 clu.fL

32,305cu.ft 30,000cu. ft.

You load 20 T of pastein a hold. It takesup 900 cu.ft. The stowagefactorof the pasteis 40.5. What is the broken stowagefor this cargo? SOLUTION: VolumeofCargo = BrokenStowage = = =

3.

20T x 40.5 = g10cu.ft. V - v xl00 V 900 - 810 x 100 900 l0%

tlow nrany tons of boxesmeasuring3' x 2' 06" x 5' and weighing 560 lbs. can be stowedin a space having a cubic capacityof 28,500cu. ft. usinga brokenstowageof l5%? SOLUTION: Stow4geFactor

= =

Cu. Capacity I t,ong Ton 3'x2.5'x5'=150

(s60t2u0) Weighr 4.

=

Cu. Capacity = 2g,500 x 0.g5 = 161.5Tons --SFa;ror 150

Your vessel'sdeadweightis 12,000T. Fuel, water, & storesare 2,500T. The grain cubic capacity is 500,000cu.ft. The stowagefactorof grain is 56. one bushelof grain occgpies1.zuscu.ft. Which of the following iVare correct? a. You canload 9,500Tof grain. c. Both a andb b. Youwill have 401,767.8bushels. d. Neithera nor b SOLUTION: 500,@cu. ft 56 500,0(X)cu. ft. -rwAnswer:

3E0

= =

8928.57T =

Maximumyoucan load

191,767.79bushels

(b)

CargoAssessmcnts

parts occupies15 cu.ft. and A tween deck measures25' wide by 14' deep.one caseof machinery Assumingthat theyare fwd bulkhead. you the against T cases 25 of going load to are weighs175lbs. will the casesextendfrom far how aft deck, tween the of height the sb;ed the width of the hatch and the forward bulkhead? SOLUTION: =

= 192 1.5 (r75122N)

sF

=

cu. ft l LT

192 x 25 25' x 14'

=

4800cu.ft. ofcargo

=

350 sq. ft. for the tudbulkhead 4900 cu. ft. = l3.7tft. 350 sq.ft.

you are to load cannedgoodsthat havethe stowagefactor of 50 and rags that havea stowagefactor of cargo weight capacity is 4,200T. Itrowmuchof each 160.The hold capacityis520,000cu.ft. The "full and down"? cargocould you load to bring tie vessel SOLUTION: wLF.=Weightofthecargohavingthelargestowagefactor WLF

=

Cu.ft. - (CargoWt x Small Stowagefactor)

WLF

=

520,000-(4,200x50) = 2818'18T Rags

ffi Weight of cannedgoods = j.

4,200.00T - 2,818'18T

=

1,381'82T

your vesselhasa deadweighttonnageof 9,000T. Bunkersare 1,500T and storesare45T. You wish 112lbs. The to loadboxesoftea and steelrods.Eachbox oftea measures2.5' x I' x 2' and weighs hasa hold capacityof 450,000cu.ft. How much of each slowagefactorof steelrodsis 14.Your vessel "full anddown"? vessel the bring you load to cargoshould SOLUTION: 9000 T Deadweight - 1545T Bunkers & stores 7455T Cargoallowed

(rr2l22n)

r Lr 14x + 100y -l4x - l4y

86v v

= 14

Cu. ft. = 2.5' x l' x 2' = 100 SF for tea

SF

x+y

SF for steelrods

=

74557

= 450,000 = - Q455xl4) =-]lf',$o= 4018.95 T tea

T 7455.00 T of tea 4018.95 = 3436.05T of steelrods

CargoAssessmznts

3E1

8'

A hold hasa deckareaof 1500 sq.ft.Youaregoingto load 150Tofcases.Eachcaseoccupies1gcu.ft. and weighs320 lbs. The hold hasa depthof 35 ft. How manyfeetabove the cargowill remainafter this cargois loaded? SOLUTION: =

Cu. Capacity I Long Ton

= =

18 (320 t2U0)

= = =

SF x Weight = 126 x 150 18,900cu. ft. 12.6' Ht. of cargo

=

22.4' remainingspaceabovethe cargo

StowageFactor

Cu. Capacity 18,900 cu. ft. 1,500 sq.ft. 35.0'- 12.6'

=126

Youareto load a consignmentof lumber.Eachpiecemeasures 4" thick, 9" wide & 15'long. Thereare 20,0m piecesin the shipment.How manyboardfeetwould be listed on the Bill of Lading?

9.

SOLUTION: B o a r d F e e t= = 45.0BoardFeetx 20,000

=

UxW'xH'x12 15'x 0.75' x 0.33' x 12 = 45.0 900.000 Board feet

10. A vesselis ballastingher doublebottomtank which hasa tank top areaof 500 sq.ft.you fill thetank throughthe soundingpipe, which is 20 ft. high abovethe tank top, to within 5 ft. from the top of the pipe. If waterweight is 64 lbycu.ft., what total pressureis on the tank top? SOLUTION: = 214.297 500x15x64 2240 11.

A tank measures3' x32'x 40'. How long will it take to emptythe tank if the dischargepunp can pump 120gallonsper minute? SOLUTION: Volume = 7.48gallons =

3840cu.ft. x 7.48gallons = 120

3' x 32' x 40'= 3940cu.ft. 1cu. ft. 239.4mins. or 3h 59m 21s

72. After loadinga cargoof casingheadgasolineon a tanker,yourullagesshowa total of 110,205bblsat atemp.of76"F. If theAPlgravity at60"Fis64.7 andthecoefficientof expansionof thecargois 0.0007,how many barrelsshouldbe listedon the Bill of Lading? SOLUTION: LoadingTemp. 76"F -60" F StandardTemp. Diff.inTemp. = l5"F Coef.of Exp. --Reduadon

3E2

=

l\{ = = M =

1.0 - Reduction 1.0 - 0.0112 0.9888

x 0.0007 --TT-m

CargoAssessments

Net Barrels

=

GrossBarrelsx M

= 110.205 bbs.x 0.9888 Net Barrels

= 108,970.7trbls.

13. Your cargovesselhas a doublebottomtank with a capacityof 10,000cu.ft. You will to load liquid cargotiat has an API gravity at 60 "F of 25.9. The cargohas 1.124bbls/longton and occupies40 cu.ft./longton. You want to load 1770bblsat 60 "F and expectto heatthe cargoduring the voyageto not more than 80 "F. Which of the following is/arecorrect? a. The tank hasa capacityof 1781barrels. b. The cargowhenexpandedto 80 "F will overflowthe tank. c. Both a and b d. Neithera nor b Answer:

(c)

solurroN: Tank Capacity 10,000cu.ft. = 40 cu.ft./LT

250LT capacity

Tankcapacity- 250LT x 1.l24bbls/LT = 1781bbls. 1770bbls at 60 "F. Apl 25.9 = multiplier of 0.9921 Net Barrelsat 60 "F = m x GrossBarrels Net Barrelsat 60 "F = 0.9921x? ? = 177010.9921 = 1784.09bbls. Thetank will overflow if heatedto 80 "F. 14. A tank hasa capacityof 90,000barrels. You load 88,200bbls.at 60 "F of a conunodityhaving an API at 60 "F of 58.3. To what temperaturecould this commoditybe heatedbeforethe tank overflows? b. 93 "F c. 98 "F a. 85 "F d. 99 "F Answer: (b) SOLUTION: Net Barrels @ 60 "F 88,200 m API 58.3

= =

m x GrossBarrels mx90,000

=

88.200=0.9800 90,'000 Group 3 = kmp. of a little lessthan 93 "F

=

15. What is the volumeat 60 'F of 8000U.S. gallonsof oil measuredat 90 "F whenthe gravity of the oil is 61.1API at 60 "F and them factoris 0.9818? SOLUTION: Net Volume@ 60 "F

=

GrossVolumex m factor

=;r:;'J:::,,"* CargoAssessments

383

EXERCISES: 1.

You are in the processof loading 465,000 barrels of cargo oil. At 1030H, on 5th November,you gauged the vesseland found out that you haveloaded203,000barrels.At 1200H,you found out that you have loaded218,000 barrels. If you continue loading at the sarnerate, your completion time will be on: c. 0735H 7th November a. 1242H 6th November November d. 1104H 6th November b. 1510H 5th

2.

A vessel'stropical loadlineis 6" above her summerloadline.Her TPI is 127tons.Shewill arrive in the summer mne 8 daysafter deparnre. Shewill burn off about47 tonV day of fuel oil and will 12tonsofwater lday.IIow manytonsmaysheloadabovehersummerloadlineif sheloads consurne in the tropictlznne? c. 376T d. 10167 b. 762T a. 472T

3.

What is the volumeat 60oFof 6000 barrels of oil measuredat 45"F when the gravity of oil is 57.8 API at 60"F and the M factoris 1.00917? b. 5833 barrels c. 5946 barrels d. 61M barrels a. 6055 barrels Gasoline having a coefficient of 0.0006 per deg. F is loaded at 60 "R The voyageanticipated temperatureis up o 74 "F. Allowing for expansion, how many barrels should be loadedin a tank

4.

capableof taking 10,000barrels? b. 9958 barrels a. 9916 barrels

c.

10000 barrels

d.

10084 barrels

5.

An oil cargohasa coefficientof expansionof 0.0005per deg.F. If this cargois loadai at 70"F and a cargotemperatureof 90"F is expectedat the dischargeport" how many barrels would 1ou expect to unload if you loaded 10,000barrels? c. 9,990 barrels d. 9,900 barrels b. 10,010 barrels a. 10,100 barrels

6.

A cargoweighing 100tonswith a stowagefactorof 50 is to be loaded.Allowing brokenstowageof 5Vo,how much volumewill the cargooccupy? d. 6,750cu.ft. b. 7,000cu.ft c. 6,150cu.ft.. a. 5 ,2 63 cu.ft.

7.

A cargoweighing 100 tons with a stowagefactor of 40 is loadedin a spacehaving a capacityof 6,000 cu.ft. What will be the remainingspipeallowing 57obrokenstowage? c. 1,900cu.ft. d. 1,700cu.ft. b. 2,000 cu.ft. a. 1,789 cu.ft.

8.

How many tons of marble with a stowagefactor of 20 can be loadedin a hold having a capacityof 40,000cu.ft. Allow 5Vofor brokenstowage? c. 2,100 tons d. 2,050 tons b. 2,000 tons a.1,900 tons

9.

A vesselis fifted with deeptanks with a capacityof of 1,000 tons of fresh water. What quantity of peanutoil with a specific gravity of 0.93 could be transportedin such tanks? c. 1000 tous d. 10E0 tons b. 960 tons a. 930 tons

10. How many board feet of dunnagewould you estimateto be in a stackwhoseoutsidedimensionsare 6 fL high, 4 ft. wide,and 14 ft.long? d. 4050 boardfeet a. 4032 brlaldterut b. 40t23boardfeet c. 4000 boardfeet 11. If the rateofloadingata given port is about 30 tonsperganghourforbaggedflour, how long it would take to load 600 tons,usingnro gangs? d. 13 hours c. 12 hours b. 11 hours a. 10 hours

384

CargoAssessments

12. If 2,000tons of iron ore with stowagefactor of 15 is stowedin a cargo hold of rectangular shapewhose bottom is 50 ft. long and 45 ft. wide,what is the height of the centerof gravityof the ore abovethebottomof the hold? d. 15.00 fr. c. 13.33 ft. b. 6.00ft. a. 6.67ft. 13. You.are going to load 8,500 grossbarrelsof IraniancrudewithanAPlof32.6at100"F. How mueh will you load in net barrelsif the M factoris 0.98214? d. 8230.5 bbls. c. 8590.8 bbls. b. 8600.9bbls. a. 8348.2 bbls. 14. Youare going to load 5,000 grossbarrelsof Bintulucrudewith an APIof29.4 at95"F. How much will you load in net barrelsif the M factoris 0.98490? d. 4806.6 bbls. c. 4900.8 bbls. b. 5200.6bbls. a. 4924.5 bbls.

PACKAGE PICTORIAL INSTRUCTIONS

zI ^.

FRAGILE HANDLE WITHCARE

THIS WAYUP

O4 HEAVYWEIGHTS THISEND

USE NO HOOKS

il

SLINGHERE

%

KEEPCOOLSTOWAWAY FROMBOILERS

Cargo Assessments

38s

OIL TRANSFEROPERATION

Before any Oil T[ansfer Operation commenceq Duty Oflicer to inspect the following : 1.

Emergencytowing wires correctlypositioned.

2.

All scuppersclosedand oil tight.

3.

All applicablewarning signsposted.

4.

Vessel'ssafetyplan (kept at emergencyheadquarter)postedat gangway'

5.

Hosescorrectlyconnected.

6.

Drain valveson drip traysclosed.

7.

Drain valveson manifold closed.

8.

All unusedcargoandbunker connectionsclosedand blankedoff.

9.

room doorssupposedto be closedare really closed. Accomodation/eugine

10. Gangwaysafelyrigged.

During Transfer Operation : 1.

Frequently,at leasteveryhour to checkullageson tanksbeing worked.

2.

Everyhour during discharging,notepumpingpressureand dischargingpressure.

3.

Flaveemergencytowing wires adjustedasnecessary.

4.

Ilave mooring lines adjustedasnecessary.

5.

Flavegangwayadjustedasnecessary.

6.

F{aveany abnormalstrainson hosesadjusted.

7.

Tiakeproperaction in casewaterbuilds up on deckand/orat scuppers.

8.

Ensurethat oneman is alwayspresentcloseto the manifolds.

ULLAGE 386

INNAGE

THIEVAGE

DEFINITION OF TERMS Added Weight Method. A method of solving for damagestability where the water which entersthe vesselis consideredan addedweight. Block Coeffii:ient A coefficient of finenesswhich expressesthe relationship between the volume of displacementand a block having the length,breadth, and draft of the vessel.

opening.This angleis themaximumangleat which the intact stability curvesarevalid. Draft. The linear distancefrom the bottom of the keel to the watedine. Dynamical Stability. The energywhich a vessel possesses to right herselfdueto the work performed in inclining her.

Center of Buoyancy. That point at which all the Equillbrlum. Vesselin a statewherethereis no movevertically upward forcesofbuoyancyare considered menl G mustbein the sameverticallinewith B. to be concenEated;the oenterof volume of the imFactor of Subdivision.A numberless than 1 obmersedportion of the vessel. tained from crrves of factor of suMivision which Center of Flotation. The center of gravity of the whenmultiplied by floodablelength,producesperwaterplane;the point aroundwhich a vesseltrims. missiblelengthof compartment.It is the reciprocal Center of Gravity. That point at which all the ver' of the compartmentstandard. tically downwardforcesof weight are consideredto FloodableLength. At anypoint of a ship,the length be concentrated;the centerof the massof tle vessel. of the spacehaving its centerat that point, which Changeof Tbim. The algebraicsum of the initial canbe floodedwithout causingthe ship to sink. trim and the trim after weight has been shifted, Founder.To sink due !o lossof reservebuoyancy. loaded,or discharged. CompartmentStandard. The numberof compart- Freeboard.The distancefrom the waterlineto the ments in any location which can be flooded up to upperdeck. the margin line without causingthe vesselto sink. Free Surface. Conditionexistrngwhen a liquid is Basedon a certain perrreability, usually 637o for free to movein the tank or compartmentof a vessel. cargospacesmd 80Vofor machineryspace. Causesa virtual rise of the ship'scenterof gravity. Couple Mornent. Createdby fwo equal forces ex- GM. Metacentricheigh[ distancefrom the center ertedin oppositedirections and along parallel lines. of gravity to the transversemetacenter. In stability, the forcesthrough G and B. Heel. The transverseansle of inclination of a vesCrank Ship or Tender Ship. A vesselwith small sel. rietacentricheight; top-heavy. Heeling Moment. The momenttendingto heelthe Density.The weightperunit volumeof a substance. vessel.Opposedby the righting moment. Displacement.The weight of water displacedby a Ilydrostatic Curves. Cunresbasedon the form of floating object. Equal to the weight of the object. the immersedportions of a vessel.They include: TPI, displacementin saltand of fr^reness, coefficients DownfloodingAngle. The angleof heelwherewaheight of B andM abovethekeel, MTI, fresh water, ter will first enter the hull of a vesselthrough an

Stabili* andTrim

387

increaseof displacementfor onq foot trim by the stern. Initlal Stabillty. Stability of a vesself,orsmall anglesof inclination(up to l5 deg.). Intact Buoyancy.Intact spacebelowthe surfaceof a floodedarea. Inclining Experiment. Experiment which, by inclining a vessela few degrees,produceswim trre aia of a formula the meracenrric heighr rcr*rl a"J tr,e position of the center of gravity of a vessel.

Permeabilltyof Surface.Thepercentage of thesurfaceof a floodedcompartmentwhich is occupiedI water. Permissiblelength. The maximum length permitted betweenmain transvenebulkheads.Found by multiplyingfactorof suMivisionby floodablelength. stability' The end range of stabilitv is i:f:,:l at an angle of inclination when righting arm fTTq Practically' tlle range of stability is it-T:"li: iro' ended shortly after deck edge immersion in most vessels.

KB. Linear distance from the keel to the center of

(whenvesselis upright.) buoyancy. KG. Height of center of gravity above keel. KM. Height of metacenter above keel. Light Displacement. Weight in long tons of vessel in a light condition. List. Transverse angle of inclination of a vessel. Load Displacement. Weight of vessel in long tons when fully loaded. Longitudinal Stability. The tendency of a vesselto return to its original longitudinal position. Mean Draft. That draft midway between the draft forward and draft aft. Metacenter. The highest point to which G may rise and still permit the vesselto have positive stability. Found at the intersection of the line of action of B when the ship is erect with the line of action of B when the ship is given a small inclination. Metacentric Radius. Distance between B and M. Moment. Created by a force or weight moved through a distance. Negative Stability. Exists when G mincides with M. The vesseldoes not tend to return to an upright position if inclined, nor to continue its inclination if thc inclining force is removed. Parallel Sinkage. Vessel increasesher draft so that the drafts forward and aft are increasedby the sane amount; increaseof draft without change of trim. Permeability. The percentageof the '.olume of a compartment which can be occupiee by water if fltxlded.

388

volumeorall intactspace m;ff""#,::,H]:tn" Rfghting Ann The distance between the line of force through B and the line of force through G, when there is positive stability. Righting Moment. The product of the weight of the vessel (displacement) and the righting arm (GZ). Rolling Period. The time it takes a vesselto make a completeroll, that is, from port to starboardand back to port again. Stability. The tendency of a vessel to return to an erect position after being inclined by an exterior force. Stabilogauge. A devicewhich automatically calculates GM when actuators indicating weights loaded or discharged are turned. Statical Stability Curves. Curves for various displacementsup to and past load displacement.The ordinates are angles of inclination. Intersection of ordinates with curves produces the abscissae(righting arms). Stable Equilibrium. Exists when M is aboveG. A vessel will tend to return to an erect position if inclined to a small angle. Stiff Ship. Vesselwith low center of gravity and Iarge rnetacentric height. Synchronous Rolling. Occurs when the rolling period of the vessel is the same as the wave period; a condition to be avoided. TCG. Transverse position of center of gravity. TPI. NuniBer of tons necessaryto change the mean draft of a vessel by one inch; varies with draft.

Stability and Trim

+

'frim.

The dil'terencebetweenthe drafs tbrward and

alt. Urstable llquilibrium- Exists when G is above M' Ve,sseldoes not tend to return to an erect position altcr being inclined but, for small angles, tends to continuc inclination' Vertical Center of Gravity (VCG)' The vertical hcight of the center of gravity of a compartment abtxe its bottom, or of the center of gravity of a vessel above its keel. "swinging" moVirtual Rise of G- Causedby the ti0n o[ water in a slack tank. Volume of Diqplacement. The volume of water displaced by a floating object; weight of this volume of

water is equal to the-,weightof the ot{ect' Volumetric Heeting Monrent. A moment produccd by a volume acting through a distance.Units of volumetric heeling moment are in feet4, or metersa'If a volumetric heeling moment is divided by a stowagc factor, a weight moment will be produced, as done in the practice of stability calculation tbr bulk grain' Water Plane. The plane defined by the intersectittn of the water in which a vessel is floating with the vesselsides. Water Plane Coefficient. A coefficient of finencss which expressesthe relationship between the area of tlle water plane and a rectangle having thc lengtlt and breadth of tlle vessel at that water planc.

STABILITY NOMENCLATURE

G B M

Centerof GravitY Centerof BuoyancY

B1

Metacenter Shifted Centerof BuoYancY

BM GM

MetacentricRadius MetacentricHeight

Righting Arm GZ Heightof Centcro[ BuoYancY KB Heightof Metacenter KM AxGZ RightingMoment = = KG+GM KM = KB+ BM KM

Stabilin and Trim

38e

STABILITY AT LARGE ANGLES OF INCLINATION MetacentricHeight (GM) is valid only for initial stability.The coupleor righting mJment (in foor tons) is usedto indicatestability at'arge anglesof inclination. Momentof Statical Stability is tlre momentwhich will try to retum a ship to the upright when sheis heeled.It is "Positive" if it tendsto right the ship and "Negative"if it tries to causeher to heel still furtherover. Momentof StaticalStability = Disp. x GZ Thelengthanddirecrionof Righting I_ever(GZ) aloneis an indication of ship's staticalstability at anyangleofheel. Sin0=GZIGM G Z = G M x S i n0

2) Vessel"flops" to port or stbd. 3) A very long slow rolling periodaboutthe angle of permanentlist. 4) If a small GM is known plus any of theabove. Corrective measures: 1) Add low weightsymmetricallyaboutcenterline. 2) Removehigh weightsymmetrically. 3) Moveweight down symmerically. 4 ) Eliminateany free surface. Purpose: To move tle Centerof Gravity down to a posi_ tion below the metacenter. LIST CAUSEDBY G BEING OFF THE CENTERLII{E Causes:

For anglesof heelof lessthan 10" or l5o we can use GM as the indication of statical stability.For largeanglesof inclination,we useGZ because M is l) Unequaldistributionof weight on eithersideof not consideredto exist for largerangles. centerlinedue to loading. Initial Stabilir) is sraticalstabilityof a shipar a very 2) Shift of weighttransversely. smallangleof heel,and indicatedby GM. 3) Addition or removalof weightunsymmetrically Rangeof Stabilily is the angularrangeoverwhich a aboutcenterline. ship will have positive statical stability. It is important becauseit indicatesthe angle to which Ifow to recognize : the ship could be heeledbeforeshewould capsize. l) Vesselassumes a permanentlist to onesideonly. A ship may developa LOLL or LIST for one of 2) Vesselhas an averagerolling period aboutthis two reasons: permanentlist. 1. G is out of the centerlineof the ship 3) If }nown weight is excesson one side. 2. NegativeGM 4) If positiveGM is known to exist. LIST CAUSED BY NEGATIVE GM Corrective measures: Causes: 1) Shiftweighttransversely to high side. l) Removalof lowweighn 2) Add weighr to high side removeweightfrom or 2) Additionof high weights. low side. 3) Moving weightsupward. 4) Free surface Purpose: How to recognize: 1) Vesselwill not remainupright andwill assumea list either to port or stbd.

3 90

To move the center of Gravity back to the centerline.Neverattemptto correcta list by theabove methodsunlessyou are certain that G is off the centerline.

Stability and Trim

LIST CAUSED BY COMBINATION OF NBGATIVE GM AND G OFF THE CI]NTERLINE Cause: l) A combination of the previouscausesof list. How to recognize : 1) Vesselwill assumea pcrrnanentlist either to port or stbd (she will not floP). 2) Very slow rolling period about this perrnanent list. 3) If the known ofl--centerweight is out of proportion to list. Corrective measures : 1) Move down, add low, or removehigh weight (this may be done in such a manner to compensatefor the weight ofi the centerline at tho time). 2) Move, add, or remove weight to compensatefor the known off-center weight. 3) Eliminate any tree surfhce. Purpose : To move the Center of Gravity across to the centerline and down to a position below the metacenter. FACTORS AT.I. ECTIN(; S'TATICAI, STABII,ITY

EFFECTS OFBEAM. FREEBOARD AND CENTER OF GRAVITY 1. Increaseof BEAM increasesinitial stability (GM), BM, righting levers at all angles of hgel, and very little effect on range. 2. Increaseof FREEBOARD doesnot affect initial stability but increasesrange of stability. 3. Raising the CENTER OF GRAVITY decreases both initial stability and range. ANGLE OI.'LOLL The angleto which a ship with ncgativcGM will lie at rest in still water. If a ship is inclined to an angle greater than the angle of bll. thc GZ will tr positive, giving a moment to return tlte ship to thc angleof loll. ANGLE OF MAXIMUM

l. If the forceinclining the ship is equalto the rigltt.ing moment,the ship is in equilibrium. 2. If the inclining moment exceedsthe righting mothc ship will list ment which the ship possesses, over to the angle at which the 2 momenLsiuc again equal. 3. If the inclining moment is greaterthan the maxtmum righting moment which the ship possesscs. the ship will capsizc.The maximum righting grwer ol' a ship crccursnear the anglc ol'dcck edge immersiott.

L The position of ship's Center ol'Gravity. It dependson the loading ol-cargoand otltcr wcights in the ship. It determinesthe lengtlt ol'tlte rigltting lever (GZ). 2. The tbrm of the ship. It decidestle sltapcsol'ther emergedand immersedwedges whcn thc vessel heels.These in tunt will determine the shili of Centerof Buoyancy and lhe length of GZ; or alternatively the position of M and GM.

I,IS'[

DAN(;EROUS AN(;I,F]S OF LIST AND ROI,I,S A ship at searolls aroundits anglc tll'list. and is theretbrein danger of capsizing belirre thc statical limit occurs. Some authorities advisc using li2 tltc angle of maximum list as an arbitrary standa-rdli)r the angle of dangerouslist.

Srubility nnd Trim

391

TRIM AND STABTLITY 1. Freeboardis a measureof : a. T\e amountof reservebuoyancy. D. The initial stability of the vessel.

c. Both a andb d. Neithera nor b

What factor has the greatesteffect on the value of free surfacecorrection? a. Length of the tank b. Width of the tank c. Draft of vessel d. S.G.of liquid A vesselgoing from salt water to fresh waterwould: a. Decreaseherdraft c. Remainsthe same b. Decreaseherfreeboard d. Noneof these 4. All of the following characteristicsconcerninga large GM are correct except: a. T\eie is a greatertendencyto synchronize. c. Afast periodof roll. D. There is a lesssafetyin caseof flooding. d. Racking stressis increased. 5 . The most effectiveway to limit free surfaceeffectswould be to increasethe number of: a. Bulkheads c. Either a or b b. Longitudinal bulkheads d. Neithera nor b 6. Free communicationeffect is in direct proportion to: a. Width of spaceonly c. Both a andb b. I-ength of spaceonly d. Neithera nor b 7. When a weight is shifteddown, which of the following takesplaoe? a. The heightof CB decreases c. Metacentricheight increases b. The heightof CG increases d. The heightof metacenterincreases 8. The arnountof freeboardaffectsthe: a. Amount of reservebuoyancyof the vessel c. Both a andb b. Rangeof sability of a vessel d. Neithera nor b 9 . Freecommunicationeffectsin flooding can be removedto most advantageif: a. Completelyflood off centerdeeptanks c. If forepeakis flooded completely ,. Bdlast wing doublebonomtanks d. If high centertank is flooded

10.Changeof trim canbe calculatedby: a. Dividing the rimming momentbyTPI D. Dividing the trimming momentbyMTI

c. Either a or b d. Neitier a nor b

11. The situationexpectedof a vesselwith largeGM will: a. Ilave less tendencyto synchronizerolling c. llave more resistance!o listing D. Ride more comfortably d. Lrss likely to havecargoshift 12. lf the trim and KG of the ship will remain but free surfacecorrectionfor the fuel oil is reduced,what happensto the GM? a. Unchanged b. Increases c. Decreases d. Either b or c 13. How can you improvethe initial stabilityof your vessel? a. By filling double boEom tanks c. By removingloosewater D. By adding weight below d.Myoftheabove

392

Stability and Trim

1 4 .How would you m rke the rolling of a stiff vessel comfortable? a. b. c. d.

Add weight in the center line of the lower hold Ballast peak tanks Concentrate weight on upper wing tween deck Move weights lower

1 5 .Under which circumstancesmay ametacentric heightbe consideredan indication of a vessel'sstability? c. For all angle of inclination d In nocase

c. For large angle of inclination b. For small angle of inclination 16. GM is the measureol a. The amount of reservebuoYancY. b. Tbe initial stability of the vessel.

c. Both a and b d. Neither a nor b

1 1 .At any g1en draft, the TPI of a vessel can be found by dividing the area of waterplane by: a. 420

c'

b. 460

120

d' M0

1 8 .If additional weight is added above tlle center of gravity, the vesselwill: c. Increase GM d. All ofthe above

a. Reduce righting moments b. ReducereservebuoYancY

1 9 .How much volume of sea water will increase the vessel's displacement by 1 ton? a. 500 ltrs.

c' 64 cu. ft.

b. 35 cu. ft.

20.Which does not affect the correcuon for free surface? c. Tank width

D. Tank length

c. S.G. of the liquid

21. The volume of all watertight enclosed spacesabove water line is called: a. Reservebuoyancy b. Freeboard

c. Free surface

d' 100 gals'

d. Registered tonnage

d. Marginal stability

22. Your vessel wishes to maintain her draft from salt water to fresh water, you should: c. Dischargeballast b. Takein ballast 23. Transversestabilifymay be increasedby: a. BallastingdeePtanks b. Cradling the booms

c. Do nothing

d. Noneoftheabove

c. Both a and b d. Neither a nor b

give her an easierride? 24. your vesselis very stiff. Which of the following would you consider in order to b Both a and c. tanks bottom double a. Deballastdeepand d. Neither a nor b b. Craddletle booms

25. In regards to the center of buoyancy, which of the following statementsis correct? a. b. c. d.

It It It It

moves toward the low side of an inclined vessel. moves toward the high side of an inclined vessel. is located in the same position regardlessof displacement' is the measure of metacentric heigltt.

26. Which of the following is the reason that GM is a valid measure of only initial stability? a. Thti metacenter does not remain in the same position for large angles of inclination. b. The center of gravity shifts due to inclination' c. The center of gravity shifts above the metacenter as the vessel is inclined'

Stability and Trim

393

27. Which of tie following will increasethe height of centerof buoyancyof your vessel? a. Discharging weight from lower decks b. L,oading weight in upper decks c. Shifting weight from lower to upper decks d. Shifting weight from upper to lower decks 28. Which of the following will increase the positive stability of your vessel? a. Loading weights on deck c. Shifting weights from upper to lower decks b. Discharging weights from lower decks d. Shifting weights from lower to upper decks 29. The center of gravity of a vessel will shift away from a cargo that is being handled in which of the following cases? a. When loading weight into the vessel c. When shifting weight fore and aft b. When discharging weight from a vessel d. When shifting weight vertically 30. All a. D. c. d.

of ihe following are true concerning a stiff ship except: There is a large concentration of weight down. There is a risk that cargo could go adrift. There is a large GM. There is a small GM.

31. The value of KM at any draft may be taken from tle: a. Building plans of the ship c. Trim tables b. Hydrostatic Properties Table d. Stability letter ?2. The KM for a vesselmay be determined by: a. Adding the KB and BM b. Adding the GM and KB

c. Subtracting the KB from BM d Subtracting GM from KB

33. The normal tendency for a loaded tanker is to: c. Be stiff b. Hog c. Sag

d. Have a permanent list

34. Which of the following describesa STIFFvessel? a. Small GM c. IIas an unusually high center of gravity b. Pitches heavily d. Short rolling period 35. Which of the following describesa TENDERvessel? a. Large GM c. llas a very low center of gravity b. l-ong rolling period d. I{as a good transversestability 36. The point to which the G may rise and still permits the vesselto have a positive stability is the: a. Metacentcr b. Metacentric point c. Metacentric radius d. Tipping center 37. The distancebetweenthe waterline and the maindeck of a vesselis the: a. Freeboard b. Draft c. Plimsol mark "Deadweight" 38. The terrn is: a. The weight of the vesselin light condition b. The total internal volume of the vessel c. Cargo carrying capacity of a vessel including water, bunkers and stores d. Amount of water the vessel displaces

394

Stability anC Trim

"Deadweight"refersto the cargocarryingcapacity,fuel, waterand storesmeasuredin: 39. The term a. I-ongtons and limited by the deckline b. Shorttons and limited by govemingloadline c. Shorttons and limited by the freeboard d. I,olC tons and limited by tle govemingloadline 40. A changein trim may be simply definedas: a. The changgin differencebet. fird and aft draft b. The sum of free communicationand free surface c. The momentof inertia of the ship'swaterplane d Rolling and listing 41. If a weight is shiftedfrom the deckto the hold, which of the following will takeplace? d. KM increases c. KG increases ,. KB increases a. GM increases 42. Which of the following describesthe TPI? a. Tonsneededto changethe meandraft oneinch at a certaindraft b. Tonsneededto trim the vesselby onefoot at a cercaindraft c. Tonsneededto trim the vesselby one inch at a certaindraft canbe usedto indicate: 43. The sthbilogauge a. Initial stabilify b. Heightof metacenter

c. Height of centerof buoyancy d' The draftsfwd and aft

in a ship that resultsin seriouslossof reservebuoyancywill always: 44. Floodingof any compa.rfinent c. Causeseriouslist a. Increasethe trim heelingmoment Decrease d' D. Increaseship stability 45 The vertical shift of weightto a positionabovethevesselcenterof gravity will: c. DecreaseKG a. Increasereservebuoyancy d. IncreaseKM b. Decreasethe righting moments 46. A tank which carriesliquid is dangerousto the stabilityof a vesselwhen it is: d. Slack a. l-ow in the vessei b. Completelyempty c. Completelyfull 41. Themost importantfigue in the calculationof freesurfacefor a tank carryingliquid is: d. Breadth c. Displacement b. Length a. Depth 48. For a tanker,the most importantconsiderationis the: c. LCG ,. VCG a. GM

d. Stresson the hull

49. The amountof freeboardthe vesselhaswill affectits: c. Stabilityat largeangleof inclination a. Initial stability d. PermeabilitY b. Freesurface 50. If a vesselhasa list but maintaina regularrolling period,tlle vesselhas: c. Unsymmetricalweight distribution a. Centerof gravity is o1Tthe centerline d. List that canbe correctedby reducingKM b. NegativeGM 51. What will be the resultif containersstowedon deckare removed? c. Reservebuol'ancywill decrease a. KB will increase d. KG will increase ,. GM will increase

Stabiliryand Trim

395

with: 52. A vessel'smaximumstabilityis closelyassociated c. Both a and b a. The angleof deck-edgeimmersion d. Neithera nor b b. The anount of freeboard 53. Whencargois shiftedfrom the lower hold to the main deck,what may possiblyhappen? c. CG will moveupward a. CB will movedown No changein the stability d. increase will ,. GM 54. Whendoessaghappenwhen a ship hasbeenaground? a. When the ship'sbow and sternare both aground D. When the seabedis muddy c. When only midship is aground d. When the ship runs agroundon a rock shelf 55. A vesselwith smallGM will: c. hovide a comfortableride for crewandpassenger a. Ilave a large amplitudeof roll D. Likely to have cargoshift in heavyweather d. llave drier decksin heavyweatler 56. Your vessel has taken a hole in #2 hold. Water has entered the vesselbut flooding and free communicationwith the seahas beenchecked.Which of the following could you useto determine your stability? c. Either a or b a. Addedweight method d. Neithera nor b D. I-ostbuoyancymethod 57. When a vesselis inclined due to someexternalforce,the: c. Vessel'sCB shifts to the centerof the low side b. The vessel'sCG shifts to the centerof the low side c. Vessel'smeandraft increases 58. Thestaticstabilitycurvefo'ra givenvesselpeaksat 34", For this ship,thedangeranglefor a permanent list would be about: d. 8.5" c. 34" b. lT' a. 51" 59. If a vesselwill list with equalreadinesson eitherside,it's likely causedby: c. NegativeGM a. Pocketingof free surface d. Offcenterweight D. Excessivefreeboard 60. Freecommunicationwill adverselyaffecttransversestability only when the floodedspaceis: c. On the centerline a. Completelyflooded d. Offcenter D. Opento seaaboveandbelowwaterline 61. you are fighting fre in the hold using water.What is the most importantconcerningthe stabilityof the vessel? a. Draining fre fighting waterand pumpingoverboard b. Shuttingof damagedelectricalwiring c. Maneuveringthe vesselto put the fire on tle left side d. Removingfne debris from hold

62. Atankorcompar0nentaboardyuurshipislocatedbelowthevessel'swaterline.Ifthespaceinquestio is floodedcompletely,you would expectthe value of tie free surfacefor that spaceto: c. Vanish oompletely d. Noneof these D. De,crease a. Increase

396

Stability and Trim

in the end hatches'The vesselis:

63.Yourvesselhasthe engineamidshipand the cargois concentrated a. D. c. d.

Hoggingwith tensilesEesson the main deck Saggingwith tensilestresson the main deck stresson the main deck Saggingwith compressive sress on the main deck compressive with Hogging

g . In general,on what doesthe position of centerof buoyancydepends?

a. Irngth

c' Freeboard

b. Draft'

d' Depth

65. The centeraroundwhich a vesselis trimmedis called: c. Centerof gravitY a. Tipping center d. Turning center b. CentsofbuoYancY 66. A vesselwhosedraft is more on the sternthan tJtebow hasa: c. Set D. List a. Drag

d. Shear

that the vessel: 67. If a vesselrolls slowly and sluggisttly'this conditionindicates c. Is trimmedaft a. IIas off centerweight d. I{as Poor stability D. Is taking in water 68. Which action will affectthe trim of the vessel? c' Moving weight forward c. Ilwering of weight d' Anyof ttreabove center b. Adding weight at the tipping 69. What is MTI? a. The foot-tonneededto trim the vesselby 1 inch b. Thefoot-tonneededto trim the vesselby 1 foot c. The momentto trim the vesselby 1 foot 70. Thoseship's tanksthat are particuladyimportantfor trimming c' Deeptanks b. Settlingtanks a. Domestictanks

of the ship arethe: d' Peaktanks

loading/unloadingoperationsand weight 71. The 4 factorsafi-ectingthe ship'snew final situationduring following factorsis missing? Eansferare final draft, listing and metacentricheight.which of the a. Diltaon tank capacityand cargo spaceCG b. Summerwaterline c. Stabilitycurves(final) d. CaryosPacevolumes T2.Whichwouldnotprovideextrabuoyancyforavesselwithnosheer? c' Raisedpoopdeck a. Higherbulwarks d' Lighter draft b. Raisedforecastlehead 73. Alarge angleof list canbe createdby: a. Negativeinitial stability b. Off-centerweight

c. Either a or b d. Neither a nor b

74. A vessel'sKG is foundbY: a. Dividing the total longitudinalmomentby displacement D. SubtractingLCF from LCB c. Dividing total vertical momentby displacement

Stability and Trim

397

75. A vesselthat hasbeenholedbelow the waterlinewill sink until: a. The buoyancylost is equalto the buoyancygainedby deeperimmersion. b. The weight of the vesselactingdownwardequalto the pressureof the wateracting upward. c. Eithera or b d. Neithera nor b 76. The principal dangerfrom the liquid in a half filled tank is: a. Rupturingof bulkheaddueto shifting D. Corrosionin shifting c. Damagingtank bottomdue to shifting of liquid d l,ossof stabilitydue to free surfaceeffect 77. The displacementon the deadweightscaleis computedfor: c. The vesselat differentdrafts c. Both a and b D. The vesselin an evenkeel condition d. Neithera nor b 78. The centerof volumeof the irnmersedportion of the hull is called: c. Tipping center b. Centerof gravity c. Centerof buoyancy d. Centerof flotation 79. A damagedvesselis listing to port, and the rolling periodis long. The vesseltakesan oppositelist occasionally.What action will you take? a. Fill up an empty doublebottomtank on stbdside D. Pressup slackcenterlinedoublebottomtank c. Pumpout ballastfrom port to stM doublebottomtanks ' d. Transferall movableweightsfrom port to stbd 80. which of the following is not usuallya concernwhen loadingon a tanker? a. Draft c. Initial stabilirv b. Bendingmoments' d. Trim 81. When using a stabilogauge, unlessthe densitycorrectionis applied,the centerof gravity of a loaded compartmentis assumedto be : a. At lB of the heightof the compartrnent c. At the geometriccenterof the comparfinent. b. Atll2oftheheightoftlecompartment d. ondeckofthecompartment 82. Usedwhen the entire length has beendivided into a numberof equal parts by an odd numberof ordinates: a. Simpson'slst rule c. Simpsor's3rd rule b. Simpson's2nd rule d. Nl of tle above 83. Stabilogauge cannotdeterminethe: a. Deadweight t. GM

c. MTI

d. Mean draft

84. A vesselis referredto as TENDERwhen theweight of cargois: a. Evenlydistributedvertically b. Concentratedlow and doublebottomsareempfy c. Concentratedhigh and doublebottomsarefull d. Concentratedhigh and doublebottomsare empty 85. As the displacementof a vess:l increases,the detrimentaleffectsof free surface: a. Increases b. Decreases c. Unchanged d. Noneofthese

398

Stabilimand Trim

86. A fresh wat€r correction is usually listed on tle ship's capacity plan. This correction gives the: a. Mean draft at light displacement when in FW b. Difference between the SW and FW capacity c. Additional draft tlat a ship may add to her Plimsol mark when loading in FW 87. An intactbuoyancy means: a. The volume of all intact spacesabove the waterline b. An intact spacebelow the surface of the flooded area c. An intact spacewhen flooded will not causethe vesselto sink d. The space where all the vertical upward forces of buoyancy ilre considered to be concentrated 88. To increase the extent of flooding your vessel can suffer witlout foundering, you could: c. Increase the reserve buoyancy D. Raise the center of gravity c. l,ower the centcr of gravity d. Ballast the vessel 89. The purposeof inclining cxperiment is to determine the: a. KM b. KG c. KB

d. Noneof rhese

90. Where could a considcrahlcamount of weight be placedon the ship without causinga changein trim? a. OverLCF l. OvcrLCG c. OverLCB d. Over midships 91. Curves basedin the form ol' l.heimmersed portions of a vessel.They include Coeffrcientof fineness, TPI, displaccmentin SW lud FW MTI, KM, KB and increasedof displacementfor one foot trim by the stern. a. Hydrostatic curves c. Cross curves of stability D. Curves of statical stability d. All of the above 92. Your vesselis damagedand partially flooded. It is listing 12 deg to port and trimmed 8 ft down by the head. It has a long, sbw, sluggish rcil. What action will you take first? a. Jettisondeck cargo frorn the portside D. Press up an aftcr, slack, centerline double bottom tank ?t c. Jettison the anchors and anchor cables d. Pump out forepeak tank 93. The ratio of volume of displacementto a hlock having length, breadth,and draft of the vesselis known :IS:

a. Beam-draft ratio b. Area of waterplane

c. Block ctrlllcient d. Block ratio

94. The most detrimental effect on initial stability is a result of lcx'neliquid: a. Flowing from fore and aft within the vessel b. Docking in a slack tank as a vesselrolls c. Flowing in and out of the holed wing tanks d. Flowing from side to side within the vessel 95. The percentageof the total surface area or volume of a flooded compartment that can be crcupied by water causedby damage is called: a. Form gain c. Permeability b. One compartment standard d. Centcr of lloirhtion

Stohility and Trim

399

96. Freesurfacecorrectionshouldbe: a. Added to the GM to obtain the correctedGM b. Subtractedto the GM to obtain the conectedGM c. Obtainedby dividing the total free surfaceby the total verticalmoment 97. The amountof tonsrequiredto be loadedor dischargedon the tipping centerof an evenkeel ship to increaseor decreaseher draft by 1 inch is: b. Registertons c. Headtons d. Tonsperinchimmersion a. lmmersion 98. The point whereall the verticaldownwardforcesof weight are consideredto act is known as: b. CenterofGravity c. CenterofBuoyancy a. Metzcentpr 99. The algebraicsumof initial and final trim is: b. TPI a. Trim

c. Mean draft

d. Changeof trim

100. Theresidualtonnageafter variousallowancesfor machinerycrew'squarterandnavigationspacesare deductedfrom grosstonnageis: c. Net tonnage a. Displacementtonnage d. Underdecktonnage D. Deadweighttonnage has: 101. A vesselsubjectedto SAGGING a. Bottomplating undertensilestress D. Transversebending

c. Main deck undertensilestress

102. The practiceof filling in doublebottomtanksto enhancestability is: c. Ballasting b. Weighing a. Inclining

d. Trimming

103. The conditionbroughtaboutwhen the hull of the vesselis supportedby nvo wavesat both endsis: D. Hogging c. Canting d. Bending a. Sagging 104. The momentof any point in a ship's structurethat tendsto producesaggingor hogging is: b. Sheer c. Racking d. Bending a. Torsion 105. The total time in secondsfor a vesselto roll from starboardto port to starboard,or vice-versais: D. Interval of roll c. Inclining period d. Averageroll a. Rolling period 106. The Archimedesprinciplestatesthat whena bodyis wholly or partially immersedin a fluid it appcars to sufferlossin massequalto: c. Weight of the immersedportion a. The areaof underwatersurface d. Tbe massof the fluid it displaces b. The force of buoyancyacting on it 107. A tankerfully loadedwith oil pumpedout from the sternmosttank across.What will be the effecton the draft? c. The fwd draft will decrease a. The fwd draft will increase d. No effect on the draft b. The aft draft will increase 108. A vesselis said to be in stableequilibriumwhen: a. The centerof gravity is abovethe metacenter b. The metacentricheight is positive c. The metacentricheight is negative d. Alloftheabove

400

Stabilin and Trim

CALCT]LATION KG

OF KG or

= Total Vertical Moments TotalWeights

VCG

= Momentdueto shift Displacement

VerticalShift of G or GG'

Note: Include lightship weight and momcnts, = WxD Disp.

Note: or discharged D = Distanceaboveor belowthe Centerof Gravity if the weightis loaded D = Distanceweightis shifiedwhenweightis alreadyon board' VCG of a Hold = Weightx VCG Moment + Ht. of the D. Bottom = Total Moments VCG of aHold Tot"t Weights

KG of aHold

CALCI.JLATION OF GM GM

=

KM-KG

Rolling Period or T

=

0.44 x Beam

./ cM

or cM = g?9'

Note : IJse0.44 for feet and 0.797for nzters. CALCI.]LATION OF KM KM

=

KB+BM

KB

=

0.53xDraft

For rectangularwater planesuchas barge:

=

I

I=Lx93l12

V

For ship wlure k is a constantdePending uponthe value ctfthe walerplanecofficient: I=Lx83xk

B

M

V=Displacementx35

INCLINING EXPERIMENT CM

=

WeightxDistance _ x TangentAngle of Heel Oisptacement

DIST.

=

GM x Displacementx Tan Angle of Heel Weight

Stabilin and Trim Calculations

401

wT.

=

GM x Displacementx Tan Angle of Heel

F

MOMENT TO HEEL 1"

=

Displacementx GM

s7.3

Note: Weight Dist.

= =

FREESURFACE

Wt. shifted Dist thal thz cargo is shifted

For salt water : FreeSurfaceConstant =

For liquids othcr than SaltWater: ld FreeSurfaceConstant = rlb3 420 420 FreeSurfaceCorrectionor GG' = F.S.Constant

nrspTAmenr Note:

GG' = 1 b = r

Risein G or Reductiontn CU or F.S.Correction lzngth of the ta* Breadthofthc tank S.G.of Liquid in the Tartk S.G.of Waterin which vesselfloats

TRIM Displacement

=

Displacemen[ Block Coefficientor b

= =

LxBxDxb 35* Draft in inchesx TPI Vol. of Displacement LxBxD Weightx Distance

MTI

=

k (TPr)2/ B

k

=

a constantdependinguponthe valueof the block cofficient.

Changein Trim

*35 for Salt Water 36for FreshWater

Note: Changein Trim is the TOTAL changein draft for boththe bowand sternin inches.

For example: Block Coefficient 0.65 0.75

0.8s MTI Changein Mean Draft

= =

k 28 30 32 GM.- x Displacement 12xL !&lgt t Loadedor Discharged TPI = L x B x p Waterplane Area 12x35 420

Waterplane Coef. or p

402

Stability and Trim Calculation,s

TRIM USING LCG rcG

=

Total Longitudinal Moment Total Weight

GabaftB

=*Aft

-Forward

BabaftG

=-Aft

+Forward

STABILITY FOR SMALLANGLES OF INCLINATION CrZ = GMxSin0 STABILITY FOR LARGEANGLES OF INCLINATION Wall- sided Formula: CrZ = (GM + uZBMTan2 0) Sin 0 TransverseShifr of G: Lossof GZ for OffcenterG

= GG' x Cos 0

VerticalShifi of G: [.ossor Gain of GZ = GG' x Sin 0 fughting Moment = Displacementx CtZ CTIAITGEIN DRAFT DUE TO DENSITY FreshWater

SpecificGravity Density Volume

1.000 1000ozlcu.ft, or 62.5lbs/ft3 22101bs = 36 cu. ft.

SaltWater

SpecificGravity Density Volume

1.025 1025ozlcu.ft. or 64.0 lbs/ft3 2%0lbs = 35 cu. ft.

SeaDraft D