船舶与海洋工程专业英语.pdf————————————————————————————————作者：————————————————————————————————日期：LessonOneTheNavalArchitectAnavalarchitectaskedtodesignashipmayreceivehisinstructionsinaformrangingfromsuchsimplerequirementsas“anoiltankertocarry100000tonsdeadweightat15knots”toafullydetailedspecificationofpreciselyplannedrequirements.Heisusuallyrequiredtoprepareadesignforavesselthatmustcarryacertainweightofcargo(ornumberofpassengers)ataspecifiedspeedwithparticularreferencetotraderequirement;high-densitycargoes,suchasmachinery,requirelittleholdcapacity,whilethereverseistrueforlow-densitycargoes,suchasgrain.Deadweightisdefinedasweightofcargoplusfuelandconsumablestores,andlightweightastheweightofthehull,includingmachineryandequipment.Thedesignermustchoosedimensionssuchthatthedisplacementofthevesselisequaltothesumofthedeadweightandthelightweighttonnages.Thefinenessofthehullmustbeappropriatetothespeed.Thedraft------whichisgovernedbyfreeboardrules------enablesthedepthtobedeterminedtoafirstapproximation.Afterselectingtentativevaluesoflength,breadth,depth,draft,anddisplacement,thedesignermustachieveaweightbalance.Hemustalsoselectamomentbalancebecausecentresofgravityinbothlongitudinalandverticaldirectionsmustprovidesatisfactorytrimandstability.Additionally,hemustestimatetheshafthorsepowerrequiredforthespecifiedspeed;thisdeterminestheweightofmachinery.Thestrengthofthehullmustbeadequatefortheserviceintended,detailedscantlings(framedimensionsandplatethicknesses)canbeobtainedfromtherulesoftheclassificationsociety.Thesescantingsdeterminetherequisiteweightofhullsteel.Thevesselshouldpossesssatisfactorysteeringcharacteristics,freedomfromtroublesomevibration,andshouldcomplywiththemanyvariedrequirementsofinternationalregulations.Possessinganattractiveappearance,theshipshouldhavetheminimumnetregistertonnage,thefactoronwhichharbourandotherduesarebased.(Thegrosstonnagerepresentsthevolumeofallclosed-inspacesabovetheinnerbottom.Thenettonnageisthegrosstonnageminuscertaindeductiblespacesthatdonotproducerevenue.Nettonnagecanthereforeberegardedasameasureoftheearningcapacityoftheship,henceitsuseasabasisforharbouranddockingcharges.)Passengervesselsmustsatisfyastandardofbulkheadsubdivisionthatwillensureadequatestabilityunderspecifiedconditionsifthehullispiercedaccidentallyorthroughcollision.Compromiseplaysaconsiderablepartinproducingasatisfactorydesign.Anavalarchitectmustbeamasterofapproximations.Iftherequireddesigncloselyresemblesthatofashipalreadybuiltforwhichfullinformationisavailable,thedesignercancalculatetheeffectsofdifferencesbetweenthisshipandtheprojectedship.If,however,thisinformationisnotavailable,hemustfirstproducecoefficientsbaseduponexperienceand,afterrefiningthem,checktheresultsbycalculation.TrainingTherearefourmajorrequirementsforagoodnavalarchitect.Thefirstisaclearunderstandingofthefundamentalprinciplesofappliedscience,particularlythoseaspectsofsciencethathavedirectapplicationtoships------mathematics,physics,mechanics,fluidmechanics,materials,structuralstrength,stability,resistance,andpropulsion.Thesecondisadetailedknowledgeofpastandpresentpracticeinshipbuilding.Thethirdispersonalexperienceofacceptedmethodsinthedesign,construction,andoperationofships;andthefourth,andperhapsmostimportant,isanaptitudefortacklingnewtechni...
