Lesson four esign of a ship involves a selection of the features of form, size, proportions, and other factors are open to choice, in combination with those features which are imposed by circumstances beyond the control of the design naval architect. Each new ship should do some things better than any other ship. This superiority must be developed in the evolution of the design in the use of the most suitable materials, to the application of the best workmanship, and in the application of the basic fundamentals of naval architecture and marine engineering As sips have increased in size and complexity, plans for building them have became mare detailed and more varied. The intensive research since the period just prior to World War 2 has brought about many technical advances in the design of ships. These changes have been brought about principally by the development of new welding techniques, developments in main propulsion plants, advances in electronics, and changes in materials and methods of construction All ships have many requirements which are common to all types, whether they are naval merchant, or special-purpose ships. The first of such requirements is that the ship must be capable of floating when carrying the load for which it was designed. A ship floats because as it sinks into the water it displaces an equal weight of water, and the pressure of the water produces an upward force, which is called the buoyancy force is equal to the weight of the water displaced by the ship and is called the displacement. Displacement is equal to the underwater volume of the ship ity of the water in which it is gloating Whe weight of the ship, including everything it carries, is equal to the buoyancy or displacement. The weight of the ship itself is called the light weight. This weight includes the weight of the hull structure, fittings, equipment, propulsion machinery, piping and ventilation, cargo-handling equipment and other items required for the efficient operation of the ship. The load which the ship carries in addition to its own weight is called the deadweight. This includes cargo, passengers, crew and effects, stores, fresh water, feed water for the boilers incase of steam propelling machinery, and other weights which may be part of the ships international load. The sum of all these weights plus the lightweight of the ship gives the total displacement; that is One of the first things which a designer must do is to detemine the weight and size of the ship and decide upon a suitable hull form to provide the necessary buoyancy to support the weight that has been chosen Oner 's requiremen Ships are designed, built, and operated to fulfill, the requirements and limitations specified by the operator and owner. These owner's requirements denote the essential considerations which are to form the basis for the design. They may be generally stated as(1)a specified minimum deadweight carrying capacity, (2)a specified measurement tonnage limit, (3)a selected speed at sea, or a maximum speed on trial, and( 4)maximum draft combined with other draft limitations In addition to these general requirements, there may be a specified distance of travel without refueling and maximum fuel consumption per shaft horsepower hour limitation, as well as other items which will influence the basic design. Apart from these requirements, the ship owner expects the designer to provide a thoroughly efficient ship. Such expectations include(1) minimum displacement on a specified deadweight carrying capacity, (2)maximum cargo capacity
Lesson Four Ship Design The design of a ship involves a selection of the features of form, size, proportions, and other factors which are open to choice, in combination with those features which are imposed by circumstances beyond the control of the design naval architect. Each new ship should do some things better than any other ship. This superiority must be developed in the evolution of the design, in the use of the most suitable materials, to the application of the best workmanship, and in the application of the basic fundamentals of naval architecture and marine engineering. As sips have increased in size and complexity, plans for building them have became mare detailed and more varied. The intensive research since the period just prior to World War 2 has brought about many technical advances in the design of ships. These changes have been brought about principally by the development of new welding techniques, developments in main propulsion plants, advances in electronics, and changes in materials and methods of construction. All ships have many requirements which are common to all types, whether they are naval, merchant, or special-purpose ships. The first of such requirements is that the ship must be capable of floating when carrying the load for which it was designed. A ship floats because as it sinks into the water it displaces an equal weight of water, and the pressure of the water produces an upward force, which is called the buoyancy force is equal to the weight of the water displaced by the ship and is called the displacement. Displacement is equal to the underwater volume of the ship multiplied by the density of the water in which it is gloating. When floating in still water, the weight of the ship, including everything it carries, is equal to the buoyancy or displacement. The weight of the ship itself is called the light weight. This weight includes the weight of the hull structure, fittings, equipment, propulsion machinery, piping and ventilation, cargo-handling equipment and other items required for the efficient operation of the ship. The load which the ship carries in addition to its own weight is called the deadweight. This includes cargo, passengers, crew and effects, stores, fresh water, feed water for the boilers incase of steam propelling machinery, and other weights which may be part of the ships international load. The sum of all these weights plus the lightweight of the ship gives the total displacement; that is Displacement = lightweight + deadweight One of the first things which a designer must do is to determine the weight and size of the ship and decide upon a suitable hull form to provide the necessary buoyancy to support the weight that has been chosen. Owner’s requirements Ships are designed, built, and operated to fulfill, the requirements and limitations specified by the operator and owner. These owner’s requirements denote the essential considerations which are to form the basis for the design. They may be generally stated as (1) a specified minimum deadweight carrying capacity, (2) a specified measurement tonnage limit, (3) a selected speed at sea, or a maximum speed on trial, and (4) maximum draft combined with other draft limitations. In addition to these general requirements, there may be a specified distance of travel without refueling and maximum fuel consumption per shaft horsepower hour limitation, as well as other items which will influence the basic design. Apart from these requirements, the ship owner expects the designer to provide a thoroughly efficient ship. Such expectations include (1) minimum displacement on a specified deadweight carrying capacity,(2) maximum cargo capacity
on a minimum gross tonnage, (3)appropriate strength of construction, ( 4) the most efficient type of propelling machinery with due consideration to weight initial cast, and cost of operation, (5) stability and general seaworthiness, and(6) the best loading and unloading facilities and ample accommodations for stowage Design procedure From the specified requirements, an approach is made to the selection of the dimensions, weight, and displacement of the new design. This is a detailed operation, but some rather direct approximations can be made to start the design process. This is usually done by analyzing data available from an existing ship which is closely similar. For example, the design displacement can be approximated from the similar ship's known deadweight of, say, 11790 tons and the known design displacement of 17600 tons. From these figures, a deadweight-displacement ratio of 0.67 is obtained. Thus, if the deadweight for the new design is, for example, 10000 tons, then the approximate design displacement will 10,000/0.67 or 15000 tons. This provides a starting point for the first set of length, beam, and draft dimensions, after due consideration to other requirements such as speed, stability, and strength. Beam is defined as the extreme breath of a ship at its widest part, while draft is the depth of the lowest part of the ship below the waterlin Length and speed These factors are related to the hull form, the propulsion machinery, and the propeller design. The hull form is the direct concern of the naval architect, which the propulsion machinery and propeller design are ??? concern. The naval architect has considerable influence on the final cisions regarding the efficiency, weight, and size of the propeller, as both greatly influence the gn of the hull form Speed has an important influence on the length selected for the ship. The speed of the ship is related to the length in term of the ratio V/VL, where v is the speed in knots and L is the effective waterline length of the ship. As the speed-length ratio increases, the resistance of the ship increases. Therefore, in order to obtain an efficient hull form from a resistance standpoint, a suitable length must be selected for minimum resistance. Length in relation to the cross-sectional area of the underwater form(the prismatic coefficient), is also very important insofar as resistance is concerned. Fast ships require fine(slender) forms or relatively low fullness coefficients as compared with relatively slow ships which may be designed with fuller hull forms Beam and stability A ship must be stable under all normal conditions of loading and performance at sea. This means that when the ship is inclined from the vertical by some external force it must return to the vertical when the external force is removed Stability may be considered in the transverse or in the longitudinal direction. In surface ship, longitudinal stability is much less concern than transverse stability. Submarines, however, are concerned with longitudinal stability in the submerged condition The transverse stability of a surface ship must be considered in two ways, first at all small angles of inclination, called initial stability, and second at large angles of inclination. Initial stability depends upon two factors, (1) the height of the center gravity of the ship above the base ne and (2)the underwater form of the ship. The center of gravity is the point at which the total weight of the ship may be considered to be concentrated. The hull form factor governing stability depends on the beam B, draft T, and the proportions of the underwater and waterline shape. For a
on a minimum gross tonnage,(3) appropriate strength of construction,(4) the most efficient type of propelling machinery with due consideration to weight, initial cast, and cost of operation, (5) stability and general seaworthiness, and (6) the best loading and unloading facilities and ample accommodations for stowage. Design procedure From the specified requirements, an approach is made to the selection of the dimensions, weight, and displacement of the new design. This is a detailed operation, but some rather direct approximations can be made to start the design process. This is usually done by analyzing data available from an existing ship which is closely similar. For example, the design displacement can be approximated from the similar ship’s known deadweight of, say, 11790 tons and the known design displacement of 17600 tons. From these figures, a deadweight-displacement ratio of 0.67 is obtained. Thus, if the deadweight for the new design is, for example, 10000 tons, then the approximate design displacement will 10,000/0.67 or 15000 tons. This provides a starting point for the first set of length, beam, and draft dimensions, after due consideration to other requirements such as speed, stability, and strength. Beam is defined as the extreme breath of a ship at its widest part, while draft is the depth of the lowest part of the ship below the waterline. Length and speed These factors are related to the hull form, the propulsion machinery, and the propeller design. The hull form is the direct concern of the naval architect, which the propulsion machinery and propeller design are ???? concern. The naval architect has considerable influence on the final decisions regarding the efficiency, weight, and size of the propeller, as both greatly influence the design of the hull form. Speed has an important influence on the length selected for the ship. The speed of the ship is related to the length in term of the ratio V/ L , where V is the speed in knots and L is the effective waterline length of the ship. As the speed-length ratio increases, the resistance of the ship increases. Therefore, in order to obtain an efficient hull form from a resistance standpoint, a suitable length must be selected for minimum resistance. Length in relation to the cross-sectional area of the underwater form (the prismatic coefficient), is also very important insofar as resistance is concerned. Fast ships require fine (slender) forms or relatively low fullness coefficients as compared with relatively slow ships which may be designed with fuller hull forms. Beam and stability A ship must be stable under all normal conditions of loading and performance at sea. This means that when the ship is inclined from the vertical by some external force, it must return to the vertical when the external force is removed. Stability may be considered in the transverse or in the longitudinal direction. In surface ship, longitudinal stability is much less concern than transverse stability. Submarines, however, are concerned with longitudinal stability in the submerged condition. The transverse stability of a surface ship must be considered in two ways, first at all small angles of inclination, called initial stability, and second at large angles of inclination. Initial stability depends upon two factors, (1) the height of the center gravity of the ship above the base line and (2) the underwater form of the ship . The center of gravity is the point at which the total weight of the ship may be considered to be concentrated. The hull form factor governing stability depends on the beam B, draft T, and the proportions of the underwater and waterline shape. For a
given location of the center of gravity, the initial stability of the ship is proportional to B/. Beam therefore, is a primary factor in transeverse stability At large angles of heel(transeverse inclination ) freeboard is also an important factor Freeboard is the amount the ship projects above the waterline of the ship to certain specified decks(in this case,to the weatherdeck to which the watertight sides extend ) Freeboard affects both the size of the maximum righting arm and the range of the stability, that is the angle of inclination at which the ship would capsize if it were inclined beyond that angle Depth A ship at sea is subjected to many forces because of the action of the waves, the motion of the ship, and the cargo and other weights, which are distributed throughout the length of the ship These forces produces stresses in the structure, and the structure must be of suitable strength to withstand the action. The determination of the minimum amount of material required for adequate strength is essential to attaining the minimum weight of the hull. The types of structural stress experienced by a ship riding waves at sea are caused by the unequal distribution of the weight and buoyancy throughout the length of ship. The structure as a whole bends in a longitudinal plane with the maximum bending stresses being found in the bottom and top of the hull girder Therefore, depth is important because as it is increased, less material is required in the deck and bottom shell. However, there are limits which control the maximum depth in terms of practica arrangement and effici From "McGraw-Hill Encyclopedia of science and Technology", Vol 12, 1982) Technical Terms 1.form船型,形状,格式 20. measurement(吨位)丈量,测量 2. proportion尺度比,比例 21.tial试航,试验 3. workmanship工艺质量 22. distance of travel航行距离 4. basic fundamentals基本原理 23. refueling添加燃料 5. marine engineering轮机工程 24. consumption消耗 6. Intensive精致的 25. initial cost造价 7. propulsion plants推进装置 26. cost of operation营运成本 8. naval ship军舰 27 unloading facility卸货设备 9. special- purpose ship特殊用途船 8 cross sectional area横剖面面积 10. buoyancy浮力 29. fineness纤瘦度 11. fittings配/附件 30. prismatic coefficient菱形系数 管路 31 slender瘦长(型) 13 通风 32beam船宽 14. cargo- handing equipment货物装卸装33 inclined倾斜的 34 external force外力 15. crew and effects船员及自身物品 35 urface ship水面船舶 16. stores储臧物 36. submarine潜水艇 17. fresh water淡水 37 submerged condition潜水状态 18. feed water给水 38 initial stability初稳性 19. boiler锅炉 39 weather deck楼天甲板
given location of the center of gravity, the initial stability of the ship is proportional to B2 /T. Beam, therefore, is a primary factor in transeverse stability. At large angles of heel (transeverse inclination ) freeboard is also an important factor. Freeboard is the amount the ship projects above the waterline of the ship to certain specified decks (in this case, to the weatherdeck to which the watertight sides extend ). Freeboard affects both the size of the maximum righting arm and the range of the stability, that is the angle of inclination at which the ship would capsize if it were inclined beyond that angle.5 Depth an strength A ship at sea is subjected to many forces because of the action of the waves, the motion of the ship, and the cargo and other weights, which are distributed throughout the length of the ship. These forces produces stresses in the structure, and the structure must be of suitable strength to withstand the action. The determination of the minimum amount of material required for adequate strength is essential to attaining the minimum weight of the hull. The types of structural stress experienced by a ship riding waves at sea are caused by the unequal distribution of the weight and buoyancy throughout the length of ship. The structure as a whole bends in a longitudinal plane, with the maximum bending stresses being found in the bottom and top of the hull girder. Therefore, depth is important because as it is increased, less material is required in the deck and bottom shell. However, there are limits which control the maximum depth in terms of practical arrangement and efficiency of design. (From “McGraw-Hill Encyclopedia of science and Technology”, Vol.12, 1982) Technical Terms 1. form 船型，形状，格式 2. proportion 尺度比，比例 3. workmanship 工艺质量 4. basic fundamentals 基本原理 5. marine engineering 轮机工程 6. intensive 精致的 7. propulsion plants 推进装置 8. naval ship 军舰 9. special-purpose ship 特殊用途船 10. buoyancy 浮力 11. fittings 配/附件 12. piping 管路 13. ventilation 通风 14. cargo-handing equipment 货物装卸装 置 15. crew and effects 船员及自身物品 16. stores 储藏物 17. fresh water 淡水 18. feed water 给水 19. boiler 锅炉 20. measurement (吨位)丈量，测量 21. trial 试航，试验 22. distance of travel 航行距离 23. refueling 添加燃料 24. consumption 消耗 25. initial cost 造价 26. cost of operation 营运成本 27. unloading facility 卸货设备 28. cross sectional area 横剖面面积 29. fineness 纤瘦度 30. prismatic coefficient 菱形系数 31.slender 瘦长（型） 32.beam 船宽 33.inclined 倾斜的 34.external force 外力 35.surface ship 水面船舶 36.submarine 潜水艇 37. submerged condition 潜水状态 38.initial stability 初稳性 39.weather deck 楼天甲板
40. righting arm复原力臂 43 unequal distribution分布不相等 41. capsize倾复 44 longitudinal plane纵向平面 42. stress应力 45 hull girder船体梁 AdditionalTerms and expressions 1. tentative design方案设计 l8 cargo capacity货舱容积 2 preliminary design初步设计 19. bale 包装舱容积 3 technical design技术设计 20. bulk cargo capacity散装货容积 gn施工设计 21 bunker capacit!y燃料舱容积 5 basic design基本设计 22. capacity curve容积曲线 6 conceptual design概念设计 23. capacity plan容量(积)图 7 inquire design咨询设计 24 stowage factor积载系数 8 contract design合同设计 25 homogenuous cargo均质货物 9. detailed design详细设计 26 gross tonnage总吨位 10 finished plan完工图 27 net tonnage净吨位 11. hull specification船体说明书 28 tonnage capacity量吨容积 12. general specification全船说明书 9. tonnage certificate吨位证书 13. steel weight钢料重量 30 displacement length ratio排水量长度比 14 outfit weight(木作)舾装重量 3 I accommodation居住舱室 15 machinery weight机械重量 32 ice strengthening冰区加强 16. weight curve重量曲线 33 drawing office制图室 17. weight estimation重量估计 34 drafting roo制图室 Notes to the Text a ship floats because as it sinks into the water it displace an equal weight of water, and pressure of the water produces an upward force which is called buoyancy. 这是一个复合句 从 because开始至句末均属原因状语从句,它本身也是一个复合句,包含有以下从句: as it sinks into the water为整个原因状语从句中的时间状语从句; it displaces an equal weight of water, and pressure of the water produces an upward 3351 原因状语从句中的两个并列的主要句子; which is called buoyancy为定语从句,修饰 an upward force 2. In addition to除.以外(还包括) 例: In addition to these general requirements,…除了这些一般要求外,还有 Tiu tE The load which the ship carries in addition to its own weight is called the deadweight h 的 in addition to应理解成“外加在它本身重量上的”,故应译为“本身重量除外(不包括本 身重量)。 插入语,相当于 for example..一般在口语中用得比较多。 4.注意“ton”,"“ tonne”,和“ tonnage”三个词的区别。ton和tone一般用来表示船舶的排水 量和载重量,指重量单位。其中ton可分 long ton(英吨)和 short ton(美吨),而 tonne为公
40. righting arm 复原力臂 41. capsize 倾复 42.stress 应力 43.unequal distribution 分布不相等 44.longitudinal plane 纵向平面 45. hull girder 船体梁 AdditionalTerms and Expressions 1. tentative design 方案设计 2. preliminary design 初步设计 3.technical design 技术设计 4.working design 施工设计 5.basic design 基本设计 6. conceptual design 概念设计 7.inquire design 咨询设计 8.contract design 合同设计 9. detailed design 详细设计 10.finished plan 完工图 11.hull specification 船体说明书 12.general specification 全船说明书 13.steel weight 钢料重量 14.outfit weight（木作）舾装重量 15.machinery weight 机械重量 16. weight curve 重量曲线 17. weight estimation 重量估计 18.cargo capacity 货舱容积 19.bale cargo capacity 包装舱容积 20.bulk cargo capacity 散装货容积 21.bunker capacity 燃料舱容积 22. capacity curve 容积曲线 23. capacity plan 容量（积）图 24.stowage factor 积载系数 25.homogenuous cargo 均质货物 26.gross tonnage 总吨位 27.net tonnage 净吨位 28. tonnage capacity 量吨容积 29. tonnage certificate 吨位证书 30.displacement length ratio 排水量长度比 31.accommodation 居住舱室 32.ice strengthening 冰区加强 33.drawing office 制图室 34.drafting room 制图室 Notes to the Text 1.A ship floats because as it sinks into the water it displace an equal weight of water, and pressure of the water produces an upward force which is called buoyancy. 这是一个复合句。 从 because 开始至句末均属原因状语从句，它本身也是一个复合句，包含有以下从句： as it sinks into the water 为整个原因状语从句中的时间状语从句; it displaces an equal weight of water, and pressure of the water produces an upward 为整个 原因状语从句中的两个并列的主要句子； which is called buoyancy 为定语从句，修饰 an upward force. 2. In addition to 除……以外（还包括……） 例：In addition to these general requirements, … 除了这些一般要求外，还有…… 而在 The load which the ship carries in addition to its own weight is called the deadweight 中 的 in addition to 应理解成“外加在它本身重量上的”，故应译为“本身重量除外（不包括本 身重量）。 3. 插入语，相当于 for example. 一般在口语中用得比较多。 4. 注意 “ton”, “tonne”, 和 “tonnage” 三个词的区别。ton 和 tonne 一般用来表示船舶的排水 量和载重量，指重量单位。其中 ton 可分 long ton (英吨)和 short ton (美吨)， 而 tonne 为公
吨: tonnage是登记吨,表征船舶容积的一种单位。 5. .. the angle of inclination at which the ship would capsize if it were inclined beyond that 从at开始至句末是一定语从句,修饰 angle,而该从句本身又由一个带虚拟语气的主从 复合句所构成。因为假设的条件不会发生,或发生的可能性非常小,所以主句和从句中的谓 语动词都采用虚拟语气
吨；tonnage 是登记吨，表征船舶容积的一种单位。 5． …the angle of inclination at which the ship would capsize if it were inclined beyond that angle. 从 at 开始至句末是一定语从句，修饰 angle, 而该从句本身又由一个带虚拟语气的主从 复合句所构成。因为假设的条件不会发生，或发生的可能性非常小，所以主句和从句中的谓 语动词都采用虚拟语气