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时间:2018-12-10
《船舶与海洋工程专业英语pdf》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、LessonOneTheNavalArchitectAnavalarchitectaskedtodesignashipmayreceivehisinstructionsinaformrangingfromsuchsimplerequirementsas“anoiltankertocarry100000tonsdeadweightat15knots”toafullydetailedspecificationofpreciselyplannedrequirements.Heisusuallyrequiredtoprepareadesignforavesselthatmustcarr
2、yacertainweightofcargo(ornumberofpassengers)ataspecifiedspeedwithparticularreferencetotraderequirement;high-densitycargoes,suchasmachinery,requirelittleholdcapacity,whilethereverseistrueforlow-densitycargoes,suchasgrain.Deadweightisdefinedasweightofcargoplusfuelandconsumablestores,andlightwe
3、ightastheweightofthehull,includingmachineryandequipment.Thedesignermustchoosedimensionssuchthatthedisplacementofthevesselisequaltothesumofthedeadweightandthelightweighttonnages.Thefinenessofthehullmustbeappropriatetothespeed.Thedraftwhichisgovernedbyfreeboardrulesenablesthedepthtobedetermine
4、dtoafirstapproximation.Afterselectingtentativevaluesoflength,breadth,depth,draft,anddisplacement,thedesignermustachieveaweightbalance.Hemustalsoselectamomentbalancebecausecentresofgravityinbothlongitudinalandverticaldirectionsmustprovidesatisfactorytrimandstability.Additionally,hemustestimat
5、etheshafthorsepowerrequiredforthespecifiedspeed;thisdeterminestheweightofmachinery.Thestrengthofthehullmustbeadequatefortheserviceintended,detailedscantlings(framedimensionsandplatethicknesses)canbeobtainedfromtherulesoftheclassificationsociety.Thesescantingsdeterminetherequisiteweightofhull
6、steel.Thevesselshouldpossesssatisfactorysteeringcharacteristics,freedomfromtroublesomevibration,andshouldcomplywiththemanyvariedrequirementsofinternationalregulations.Possessinganattractiveappearance,theshipshouldhavetheminimumnetregistertonnage,thefactoronwhichharbourandotherduesarebased.(T
7、hegrosstonnagerepresentsthevolumeofallclosed-inspacesabovetheinnerbottom.Thenettonnageisthegrosstonnageminuscertaindeductiblespacesthatdonotproducerevenue.Nettonnagecanthereforeberegardedasameasureoftheearningcapacityoftheship,henceitsuseasabasisfo
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