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首页 A-Guide-to-Ship-Navigation-Techniques

A-Guide-to-Ship-Navigation-Techniques.pdf

A-Guide-to-Ship-Navigation-Tech…

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简介:本文档为《A-Guide-to-Ship-Navigation-Techniquespdf》,可适用于工程科技领域

AGuidetoShipNavigationTechniqueswwwmarineinsightcomMarineInsight©AGuidetoShipNavigationTechniquesPublicationdateAugustAuthor:KaranChopraPublishedby:MarineInsightwwwmarineinsightcomGraphicDesign:AnishWankhede(copyrightsymbol)CopyrightMarineInsightNOTICEOFRIGHTSAllrightsreservedNopartofthisbookmayberewritten,reproduced,storedinaretrievalsystem,transmittedordistributedinanyformormeans,withoutpriorwrittenpermissionofthepublisherNOTICEOFLIABILITYTheauthorsandeditorshavemadeeveryeffortpossibletoensuretheaccuracyoftheinformationprovidedinthebookNeithertheauthorsandMarineInsight,noreditorsordistributors,willbeheldliableforanydamagescausedeitherdirectlyorindirectlybytheinstructionscontainedinthisbook,ortheequipment,tools,ormethodsdescribedhereinwwwmarineinsightcomKaranChopraisanexperiencedMarinerandaDualCertificateHolder(EngineandDeck)HehassailedasndOfficerformorethansevenyearsonalmostallmajortypesofvesselsHestaunchlybelievesinspreadingknowledgeandthereforelovesteachingInhissparetime,helikeswritingabouthisexperiencesoftheseaandconnectingwithnewpeopleAUTHORPAGE:AbouttheAuthorKaranChopraNavigationwithWind……………NavigationwithCurrent……………StoppingDistance…………UseofThrusters……………TugAssistance……………BerthingWithoutTugs……………BerthingWithAnchors……………wwwmarineinsightcomTABLEOFCONTENTS:Anavigationordeckofficerhastobeextremelycarefulwhilesteeringavesselfromitscoursenomatterwheretheshipis–atmidsea,crossingchannel,orenteringleavingaportTheteamatthebridgeshouldbeefficientenoughtosailtheshipinallkindsofwatersandweatherOneofthenaturalfactorsaboutwhicheverynavigatorshouldbeverycarefulwhilesteeringashipis–thewindVesselssuchascontainersandRoRoshipshavelargefreeboardandarethusmoreaffectedbywindsCHAPTER:NavigationWithWindPageWhenshipisatslowspeedsduringmanoeuvringorneartothecoast,winddirectioniseasytofindbutthisisnotthecasewhenoutathighseasThedirectionofthewindperceivedwhenstandingondeckisitsrelativedirectionThisistheresultantofthetruedirectionofthewindandthecoursesteeredbytheshipAGuidetoShipNavigationTechniquesPageThisexposedareaoftheshipisalsoknownasthewindageareafortheeffectofwindismoreprominentThewindeffectonthesameshipwillbedifferentatdifferentplaces,dependinguponthedraughtconditionoftheshipAwindwithforceofontheBeaufortscalewillhavesimilareffectinlightconditionaswithwindforceofwhentheshipisdowntohermarksAGuidetoShipNavigationTechniquesPageItisveryimportantfortheship’snavigatortosteertheshipconsideringthewindeffectssothattheshipcanbesteeredefficientlywithoutanydifficultyFollowingarethetechniquesanavigatormustmastertocontrolashipunderwindeffectsShipunderwaywithwindfromrightasternWhenthewindisblowingfromtherightastern,steeringtheshipbecomeseasyhowever,incaseofheadwind,thesternpartoftheshiphasthetendencytopayoffoneithersidesThisisadifficultsituationtotackleandgettingtheshipbackoncourseisnopieceofcakeSucheffectismoreoftenseenonshipswheretheaccommodationareaisattheaftregionMoreover,thewindinsuchcasehasnobrakingeffectNote:Givenachoicebetweenheadwindwindfromrightastern,theheadwindispreferredforberthingShipunderwaywithwindfromabeamWhentheshipisunderwaywiththewindflowingfromabeam,thesteeringoftheshipisnotaffectedHowever,dependingonthestrengthofthewind,theshipdriftssidewaysduetoleewayandthishastobeaccountedforwhilehandlingtheshipShipunderwaywithwindonthebowHereagaininlighterconditions,theeffectontheship’sstemislargerandthistendstheship’sheadtoswingawayfromthewind(leeward)Thisrequirestheweatherhelm(helmonthesideofthewind)tobesteeredcontinuouslyShipunderwaywithwindonquarterWhenthewindispushingtheship’ssternawaytoleeward,thesterntendstoswingtowardstheleewardTheshipisthereforesteeredtowardsthewindandtheshipisrequiredtobegivenaleehelmAGuidetoShipNavigationTechniquesPageVesselundersternwayWhentheshipisgoingastern,itrarelygoesatagreatspeedWhengoingasternmostshipsalsotendtoswingtothestarboardTheeffectofthewindisthereforealittlemorecomplexInballastconditionwherethewindcatchesthebow,whichitoftendoes,thesternispulledintothewindThiseffectisquitedefiniterapidAllshipsturnaroundapivotingpointThispointisanimaginaryreferenceandisfixedfromobservationsoftheshipturningaroundItisknownthatwhengoingasternthepivotingpointmovesaftEffectsofwindcanbeusedManoeuvreAGuidetoShipNavigationTechniquesPageAsaBRAKEForTightTurn“Thiseffectmustberememberedwhilemanoeuvringforanchoring,berthingetc”ForManoeuvreInthischapterwetakeintoconsiderationatotallydifferentaspectwhichalsoplaysanequallyimportantrolewhilemanoeuvringashipattheseaLet’sfindouthowashipcanbecontrolledundervariouseffectsofoceancurrentsCHAPTER:NavigationwithCurrentPageOceancurrentsplayaveryimportantroleinensuringthestabilityoftheshipTheeffectofcurrentsthereforemustalsobeconsideredwhenhandlingshipsinwatersEffectofcurrentsareimportantespeciallywhentheshipisundertheeffectofonshorewinds,nearoffshoreplatforms,whilemanoeuvringinnarrowchannelsandopenseas,orininlandwatersorharboursAGuidetoShipNavigationTechniquesPageTheeffectsofoceancurrentsWhentheshipisinharbourorininlandwatersandthecurrentisatconstantstrengthanddirection,theship’shandlingbecomesconsiderablyeasierThemaindifferencebetweencurrentsandwindsisthatcurrentsaffecttheshipindefiniteandpredictableways,unlikethewinddoesEveninopenwaters,whentheshipisapproachingarigoramooringbuoy,dueallowanceshouldbemadefortheeffectofthecurrentforasafermanoeuvreCurrentfromship’saheadwillreducetheship’sspeedoverground,improveshipsresponsetotherudder,andalsogivemoretimetoassessandcorrectdevelopingsituationsAGuidetoShipNavigationTechniquesPage“SuchconditionsexistonlyincomparativelynarrowchannelsofriversNavigationalofficersshouldtakeintoaccountdifferentcurrentstreamsthatcanexistoverasmallarea,withinwhichthevesselhastomanoeuvre”ShallowWaterEffectsonShips–ShipSquatWhenashipproceedsthroughwater,itpushesthewateraheadThisvolumeofwaterreturnsdownthesidesandunderthebottomoftheshipThestreamlinesofreturnflowarespeededupundertheship,causingadropinthepressureandresultingintheshipdroppingverticallyinthewaterWhentheshipdropsverticallyinthewater,ittrimsbothforwardandaftThisoveralldecreaseinthestaticunderkeelclearance,bothforwardandaft,iscalledShip’sSquatLearnmoreaboutShip’sSquathereIftheshipmovesforwardatagreaterspeedinshallowwater,wherethekeelclearanceistometres,thentherearehighchancesofgroundingattheboworsternduetoexcessivesquatAGuidetoShipNavigationTechniquesPageWhatarethefactorsthatgovernShip’sSquatThemainfactoronwhichtheship’ssquatdependsistheship’sspeedSquatvariesapproximatelywiththespeedsquaredTheblockagefactor“S”isanotherfactortobeconsideredwhileunderstandingshipsquatTheblockagefactorisdefinedastheimmersedcrosssectionoftheship’smidshipsectiondividedbythecrosssectionofwaterwithinthecanalorriverTheblockagefactorrangesfromaboutbforsupertankers,toaboutbforgeneralcargoships,toaboutshipbreadthsforcontainershipsThepresenceofanothershipinanarrowriverwillalsoaffectsquat,somuchsothatsquatscandoubleinvalueastheshippassorcrosstheothervesselHowtofindoutifashiphasenteredshallowwaterWavegenerationfromthebottomoftheshipincreases,especiallyattheforwardendoftheshipShipbecomesmoresluggishtomanoeuvreDraughtindicatorsorechosounderswillindicatechangesintheenddraughtsAGuidetoShipNavigationTechniquesPagePropellerrpmindicatorwillshowadecreaseIftheshipisin“openwater”conditionsiewithoutbreadthrestrictions,thisdecreasemaybeuptooftheservicerpmindeepwaterIftheshipisinconfinedchannel,thisdecreaseinrpmcanbeuptooftheservicerpmTherewillbeadropinship’sspeedIftheshipisinopenwaterconditionsthisdecreasemaybeuptoIftheshipisinaconfinedchannelsuchasariveroracanalthenthisdecreasecanbeuptoTheshipmaystarttovibratesuddenlyThisisbecauseofthewatereffectscausingthenaturalhullfrequencytobecomeresonantwithanotherfrequencyassociatedwiththevesselAnyrolling,pitchingandheavingmotionswillbereducedasshipmovesfromdeepwatertoshallowwaterconditionsThisisbecauseofthecushioningeffectsproducedbythenarrowlayerofwaterunderthebottomshellofthevesselTheappearanceofmudcloudwillbevisibleinthewateraroundtheship’shullwhentheshipispassingoveraraisedshelforasubmergedwreckAGuidetoShipNavigationTechniquesPageTurningCircleDiameter(TCD)increasesTCDinshallowwatercouldincreaseStoppingdistancesandstoppingtimeincrease,ascomparedtowhenavesselisindeepwatersEffectivenessoftherudderhelmdecreasesAGuidetoShipNavigationTechniquesPage“Thevessel'sturningcirclewillincreaseandtherateofturnwilldecreaseduetosquateffect”CHAPTER:StoppingDistanceEveryvesselshowsdifferentcharacteristicswhenitcomestothedistancecoveredwhenastopsignalisgivenduetodifferenceindimensions,loadingandballastconditionsPageItisveryimportantforanavigatingofficertolearntheprinciplesofpassageplanningandunderstandhisship’scharacteristicsasasmallmistakeinunderstandingmayleadtocollision,groundingorotherkindofmishapsStoppingdistanceofshipsAsweallknow,shiplikeanyothertransportutilitydoesnothavebrakestomakethemstopimmediatelyWhentheengineisgivenstoporder,theshipwillcontinuemovinginthesamedirectionduetoinertiaandwillcometostopaftermovingforsomedistanceEveryshiphastwodifferentstoppingdistances–AGuidetoShipNavigationTechniquesPageInertiaStopCrashstopAsdescribedabove,whentheengineoftheshipisstopped,theshipwillcontinuemovinginthesamedirectionforsomemoredistanceduetoinertiaHerenoasterncommandisgiven(usedtoproduce“brakingeffect”forships),andhenceshipwilltravelmoredistanceintheinertiastopmethodInertiaStopAsdescribedabove,whentheengineoftheshipisstopped,theshipwillcontinuemovinginthesamedirectionforsomemoredistanceduetoinertiaHerenoasterncommandisgiven(usedtoproduce“brakingeffect”forships),andhenceshipwilltravelmoredistanceintheinertiastopmethodCrashStopCrashstopisusuallythetermusedwhentheshiphastosuddenlystopinemergencysituationHeretheengine,whichismovinginanaheaddirectionisgivenanorderforfullastern,leavingtherudderinthemidshippositiontostoptheshipwithinminimumdistanceandshortestpossibletimeToknowthecompleteprocedureofcrashstoppingread–crashmanoeuvringAGuidetoShipNavigationTechniquesPageIngeneraloperationieberthingordepartureoftheshipfromportormanoeuvringthroughchannelornarrowpassage,theabovetwomethodsarecombinedforaswiftnavigationoftheshipieinbetweengivinganasternkicktostopandslowingdowntheship’sspeedforbettermanoeuvringThedatamaydifferwhenusedduetovariationinweathercondition,shipsloading,stabilityandotherfactorshowever,deckofficerscancomparethetraildataandmakeuseofitinpracticalsituationsAGuidetoShipNavigationTechniquesPage“Thestoppingdistancedataandchartaregiveninseatrialsoftheshipandaremadehandyonbridgeforreference”FewPracticalExamplesDependingupontheloadingconditionandthespeedoftheship,thestoppingtimewillbedifferentwhenthesetwoconditionsarechangedAlsoshipsfittedwithdieselmachinerywillhavestoppingdistancesapproximatelyofthosefittedwithSteamTurbinemachineryWhentheship’shullhasbeenduecleaning(drydock)forlongertime,thestoppingdistanceandtimewillbelessascomparedtowhentheshipisjustoutofdrydockThisisbecausethehullresistanceismoreinshipswithdrydockdonelongagoThewinddirectionandseaconditionalsoplaysanimportantroleaswindandwavesactingfrombehindtheshipwillincreasethestoppingdistanceandviceversaItisimportantforanavigationofficertoknowthesurroundingoftheshipandhowtheshipwillreacttochangesinspeedandloadingconditionsAGuidetoShipNavigationTechniquesPageCHAPTER:UseofThrustersThrustersarefittednormallyintheforeandaftpartsoftheshipThesepointsoflocationhelptocreateaturningeffectandassisttheshipinchangingthelateraldirectionduringberthingordepartingthejettyThebowthrusterissolelyintroducedinshipstoavoid,orinbetterwords,tominimizetheuseofexpensivetugboatsasmostoftheportstateauthoritiesaroundtheworldhavecompulsoryrequirementstousetugboatsforsafetypurposePage“Thrustersaretypeofpropellers,smallerinsize,whichhelpinbettermanoeuvrabilityoftheshipsatlowerspeeds”Itisextremelyimportantthatthenavigatingofficeronbridgeunderstandsthesignificanceofassistingmachinerysuchasbowthrustersduringthemostcriticaloperationperformedbyshipanditsstaff–TheberthingoftheshipFollowingpointsmustbeconsideredwhileberthingtheshipusingbowthruster:Whileusingthrustersensurethattheship’sspeedinnotmorethenknotsasabovethistheeffectcausedbythrusterswouldreduceThishappensbecauseofthemergingofthethrusterstreamwiththegeneralwaterflowonthesideoftheship’shullduetoitsforwardmovementWhenusingasingleforwardthruster,itisimportanttoconcentratemoreontheasternasthebowcanbecontrolledbytheforwardthrusterInsuchsituation,alwaysprioritizetoberthorbringtheasternoftheshipalongsidefirstandthencontroltheship’sbowWhenturningtheshipwithtwothrusterslocatedatforeandastern,thepitchofthethrustersmustbeopposingeachother,creatingaturningmomentMassivecargoshipsmustbeassistedbythetugsattheasternparttocontrolthesternmovementAGuidetoShipNavigationTechniquesPageWhenusingthebowthrusterwhiletheshipisatstop,theasternpartwillactasapivotalpointIfthethrusterisputintheportside,theshipwillturninthesamedirectionWhenusingthethrusterwithshiprunningheadway,thethruster’seffectwillbeslightlylessasboththepivotalandthrustingpointsarenowinforwardpositionWhenusingbowthrusterwithshiptravellingsternway,thepivotalpointwillbetheship’sstern,whichwillturninthesamedirectionasthatofthethrusterandactasarudderItisveryimportanttohaveanefficientsteeringgearsystemastheshipturningbyuseofthrusterishighlydependentonhowresponsivetherudder(steeringgearsystem)isThrustersareusedwhileanchoringtheshipTheyassistinturningthebowoftheshipawayfromfallinganchortoavoiddamagebytheanchorchainsAGuidetoShipNavigationTechniquesPageTugsareimportantforbothsidesinvolvedinthemanoeuvringoperationoftheshipsietheship’staffandtheportCHAPTER:TugAssistancePageUseofTugAGuidetoShipNavigationTechniquesPageByPortControlByShip’sStaffSafetyProfitSAFETYSafetyFlexibilitySAFETY“Safetyisthemostimportantaspecttakenintoconsiderationforusingtugsinportandshipberthingoperations”SelectingtheNumberofTugsTugsareextremelyhelpfulformanoeuvring,butaremonetaryburdenonshipownersaseachtugtakenforassistanceischargedahandsomeamountHowever,theyensurethemostimportantfactorsafetyoftheshipandtheport,whichcompensatesthemonetarypartTheselectionofthenumberoftugsdependsonvariousfactors:AGuidetoShipNavigationTechniquesPagePortRequirementShipandberthsizeWindageareaoftheshipAvailabilityofThrustersPowerofTugUnderkeelclearanceofshipsManoeuvringcharacteristicandpowerofship’senginePrecautiontobetakenduringTugOperationShipmustbeoperatedatlowspeed(belowknots)toeffectivelyusethetugsMasteroftheshipandtheTugoperatorsmustdiscussthelocationoftugattachmentbeforetheoperationstartsastheturningleverisdecidedbythepositionofthetugsThoseoperatingtheshipsmusthaveknowledgeabouttheoperationalcapabilitiesofdifferentkindoftugsConventionaltugsarelessflexiblethanwatertractortugsDuringoperation,tugsareusedatslowspeedtopreventforcesbetweenthetugandtheshipfrombecominglargeenoughtocapsizethetugsItisveryimportanttorememberthattheeffectivenessandsafeoperatingconditionoftugsdependonthedistancebetweenthepointofcontactandtheship’spivotpointAGuidetoShipNavigationTechniquesPageAGuidetoShipNavigationTechniquesAlwayshavealookoutonthetugfromtheshipandgivesufficienttimetothetugsforattaching,repositioning,andpullingpushingoperationsRemembertodecideandcontroltheship’sspeedwhenthetugattachedisleadingforw

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