Lesson OneThe Naval ArchitectA naval architect asked to design a ship may receive his instructions in a form ranging from such simple requirements as “an oil tanker to carry 100 000 tons deadweight at 15 knots” to a fully detailed specification of precisely planned requirements. He is usually required to prepare a design for a vessel that must carry a certain weight of cargo (or number of passengers ) at a specified speed with particular reference to trade requirement; high-density cargoes, such as machinery, require little hold capacity, while the reverse is true for low-density cargoes, such as grain.Deadweight is defined as weight of cargo plus fuel and consumable stores, and lightweight as the weight of the hull, including machinery and equipment. The designer must choose dimensions such that the displacement of the vessel is equal to the sum of the dead weight and the lightweight tonnages. The fineness of the hull must be appropriate to the speed. The draft-which is governed by freeboard rules-enables the depth to be determined to a first approximation.After selecting tentative values of length, breadth, depth, draft, and displacement, the designer must achieve a weight balance. He must also select a moment balance because centres of gravity in both longitudinal and vertical directions must provide satisfactory trim and stability. Additionally, he must estimate the shaft horsepower required for the specified speed; this determines the weight of machinery. The strength of the hull must be adequate for the service intended, detailed scantlings (frame dimensions and plate thicknesses ) can be obtained from the rules of the classification society. These scantings determine the requisite weight of hull steel.The vessel should possess satisfactory steering characteristics, freedom from troublesome vibration, and should comply with the many varied requirements of international regulations. Possessing an attractive appearance, the ship should have the minimum net register tonnage, the factor on which harbour and other dues are based. (The gross tonnage represents the volume of all closed-in spaces above the inner bottom. The net tonnage is the gross tonnage minus certain deductible spaces that do not produce revenue. Net tonnage can therefore be regarded as a measure of the earning capacity of the ship, hence its use as a basis for harbour and docking charges. ) Passenger vessels must satisfy a standard of bulkhead subdivision that will ensure adequate stability under specified conditions if the hull is pierced accidentally or through collision.Compromise plays a considerable part in producing a satisfactory design. A naval architect must be a master of approximations. If the required design closely resembles that of a ship already built for which full information is available, the designer can calculate the effects of differences between this ship and the projected ship. If, however, this information is not available, he must first produce coefficients based upon experience and, after refining them, check the results by calculation.TrainingThere are four major requirements for a good naval architect. The first is a clear understanding of the fundamental principles of applied science, particularly those aspects of science that have direct application to ships-mathematics, physics, mechanics, fluid mechanics, materials, structural strength, stability, resistance, and propulsion. The second is a detailed knowledge of past and present practice in shipbuilding. The third is personal experience of accepted methods in the design, construction, and operation of ships; and the fourth, and perhaps most important, is an aptitude for tackling new technical problems and of devising practical solutions.The professional training of naval architects differs widely in the various maritime countries. Unimany universities and polytechnic schools; such academic training must be supplemented by practical experience in a shipyard.Trends in designThe introduction of calculating machines and computers has facilitated the complex calculations required innaval architecture and has also introduced new concepts in design. There are many combinations of length, breadth, and draft that will give a required displacement. Electronic computers make it possible to prepare series of designs for a vessel to operate in a particular service and to assess the economic returns to the shipowner for each separate design. Such a procedure is best carried out as a joint exercise by owner and builder. As ships increase in size and cost, such combined technical and economic studies can be expected to become more common.(From “Encyclopedia Britannica”, Vol. 16, 1980)Technical terms1.naval architect 造船工程（設(shè)計(jì)）師32.scantling 結(jié)構(gòu)（件）尺寸naval architecture 造船（工程）學(xué)33.frame 肋骨2.instruction 任務(wù)書(shū)、指導(dǎo)書(shū)34.classification society 船級(jí)社3.oil tanker 油輪35.steering 操舵、駕駛4.deadweight 載重量36.vibration 振動(dòng)5.knot 節(jié)37.net register tonnage 凈登記噸位6.specification 規(guī)格書(shū)，設(shè)計(jì)任務(wù)書(shū)38.harbour 港口7.vessel 船舶39.dues 稅收8.cargo 貨物40.gross tonnage 總噸位9.passenger 旅客41.deductible space 扣除空間10.trade 貿(mào)易42.revenue 收入11.machinery 機(jī)械、機(jī)器43.docking 進(jìn)塢12.hold capacity 艙容44.charge 費(fèi)用、電荷13.consumable store 消耗物品45.bulkhead 艙壁14.light weight 輕載重量、空船重量46.subdivision 分艙（隔）、細(xì)分15.hull 船體47.collision 碰撞16.dimension 尺度、量綱、維（數(shù)）48.compromise 折衷、調(diào)和17.displacement 排水量、位移、置換49.coefficient系數(shù)18.tonnage噸位50.training 培訓(xùn)19.fineness纖瘦度51.fluid mechanics 流體力學(xué)20.draft 吃水52.structural strength 結(jié)構(gòu)強(qiáng)度21.breadth船寬53.resistance阻力22.freeboard 干舷54.propulsion推進(jìn)23.rule 規(guī)范55.shipbuilding 造船24.tentative 試用（暫行）的56.aptitude （特殊）才能，適應(yīng)性25.longitudinal direction 縱向57.maritime 航運(yùn)，海運(yùn)26.vertical direction 垂向58.polytechnical school 工藝（科技）學(xué)校27.trim 縱傾59.academic 學(xué)術(shù)的28.stability穩(wěn)性60.shipyard 造船廠(chǎng)29.shaft horse power 軸馬力61.electronic computer 電子計(jì)算機(jī)30.strength強(qiáng)度62.owner 船主，物主31.service航區(qū)、服務(wù)63.encyclop(a)edia 百科全書(shū)Additional Terms and ExpressionsEngineers (SNAME) 美國(guó)造船師與輪機(jī)1.the Chinese Society of Naval Architecture工程師協(xié)會(huì)and Marine Engineering (CSNAME) 中10.Principle of naval architecture 造船原理國(guó)造船工程學(xué)會(huì)11.ship statics (or statics of naval2.the Chinese Society of Navigation 中國(guó)航architecture) 造船靜力學(xué)海學(xué)會(huì)12.ship dynamics 船舶動(dòng)力學(xué)3.“Shipbuilding of China” 中國(guó)造船13.ship resistance and propulsion 船舶阻力4.Ship Engineering 船舶工程和推進(jìn)5.“Naval 安定 Merchant Ships” 艦船知14.ship rolling and pitching 船舶搖擺識(shí)15.ship manoeuvrability 船舶操縱性6.China State Shipbuilding Corporation16.ship construction 船舶結(jié)構(gòu)(CSSC) 中國(guó)船舶工業(yè)總公司17.ship structural mechanics 船舶結(jié)構(gòu)力學(xué)7.China offshore Platform Engineering18.ship strength and structural design 船舶Corporation (COPECO) 中國(guó)海洋石油強(qiáng)度和結(jié)構(gòu)設(shè)計(jì)平臺(tái)工程公司19.ship design 船舶設(shè)計(jì)8.Royal Institution of Naval Architects20.shipbuilding technology 造船工藝(RINA) 英國(guó)皇家造船工程師學(xué)會(huì)21.marine (or ocean) engineering 海洋工程9.Society of Naval Architects and MarineNote to the Text1. range from A to B 的意思為“從 A 到 B 的范圍內(nèi)”，翻譯時(shí)，根據(jù)這個(gè)基本意思可以按漢語(yǔ)習(xí)慣譯成中 文。例：Lathe sizes range from very little lathes with the length of the bed in several inches to very large ones turning a work many feet in length.車(chē)床有大有小，小的車(chē)床其車(chē)身只有幾英寸，大的車(chē)床能車(chē)削數(shù)英尺長(zhǎng)的工件。2. Such that 可以認(rèn)為是 such a kind/value 等的縮寫(xiě)，意思為“這樣的類(lèi)別/值等以至于”。譯成中文是，可根據(jù)具體情況加以意譯。例：The depth of the chain locker is such that the cable is easily stowed.錨鏈艙的深度應(yīng)該使錨鏈容易存儲(chǔ)。Possessing an attractive appearance, the ship should have the minimum net register tonnage,the factor on which harbour and oyher dues are based.Possessing an attractive appearance 現(xiàn)在分詞短語(yǔ)，用作表示條件的狀語(yǔ)，意譯成“船舶除有一個(gè)漂亮的 外形”。一般說(shuō)，如分詞短語(yǔ)謂語(yǔ)句首，通常表示時(shí)間、條件、原因等。The factor on whichare based 中的 the factor 是前面 the minimum net register tonnage 的銅謂語(yǔ)，而 on whichare based 是定語(yǔ)從句，修飾 the factor。4. Electroniccomputers make it possible to prepare series id designs for a vessel to operate in a particular service and to assess the economic returns to the shipowner for each separate design.句中的 it 是形式賓語(yǔ)，實(shí)際賓語(yǔ)為不定式短語(yǔ) to prepare series of designs 和 to assess the economic returns Lesson TwoDefinitions, Principal DimensionsBefore studying in detail the various technical branches of naval architecture it is important to define chapters. The purpose of this chapter is to explain these terms and to familiarise the reader with them. In the first place the dimensions by which the size of a ship is measured will be considered; they are referred to as principal dimensions. The ship, like any solid body, requires three dimensions to define its size, and these are a length, a breadth and a depth. Each of these will be considered in turn.Principal dimensionsLengthThere are various ways of defining the length of a ship, but first the length between perpendiculars will be considered. The length between perpendiculars is the distance measured parallel to the base at the level of the summer load waterline from the after perpendicular to the forward perpendicular. The after perpendicular is taken as the after side of the rudder post where there is such a post, and the forward perpendicular is the vertical line drawn through the intersection of the stem with summer load waterline. In ships where there is no rudder post the after perpendicular is taken as the line passing through the centre line of the rudder pintals. The perpendiculars and the length between perpendiculars are shown in Figure 1.The length between perpendiculars (LBP) is used for calculation purposes as will be seen later, but it will be obvious from Figure 1 that this does not represent the greatest length of the ship. For many purposes, such as the docking of a ship, it is necessary to know what the greatest length of the ship is. This length is known as the length of the extreme point at the after end to a similar point at the forward end. This can be clearly seen by referring again to Figure 1. In most ships the length overall will exceed by a considerable amount the length between perpendiculars. The excess will include the overhang of the stern and also that of the stem where the stem is raked forward. In modern ships having large bulbous bows the length overall LOA may have to be measured to the extreme point of the bulb.A third length which is often used, particularly when dealing with ship resistance, is the length on the waterline LWL. This is the distance measured on the waterline at which the ship is floating from the intersection of the stern with the waterline to the length is not a fixed quantity for a particular ship, as it will depend upon the waterline at which the ship is floating and upon the trim of the ship. This length is also shown in Figure 1 .BreadthThe mid point of the length between perpendiculars is called amidshipsand the ship is usually broadest at this point. The breadth is measured at this position and the breadth most commonly used is called the breadth moulded. It may be defined simply as the distance from the insid