第一篇：船舶与海洋工程专业英语

船舶与海洋工程专业英语复习笔记

Unit 1

Ship Types Lecture 1

The Criterion of Translation 专业词汇学习

The Family Tree of Merchant Ships 商船分类 Group 1: Ocean Going Ships 远洋船舶 Subgroup 1: Passenger ships 客船

Passenger liners 客班船

Passenger and cargo ship 客货船 Subgroup 2: Cargo carrying ships(tramp or liner)

货船，不定航线、不定日期船或班船

General cargo ship 杂货船

Multipurpose(general purpose)ship 多用途船

Bulk carrier 散装货船, with the special forms:

Combination carrier 兼用船； Collier 运煤船

Ore carrier 矿砂船； OBO 矿、散、油船

Timber carrier 运木船 Tankers, pided into: Crude oil carrier 原油船：VLCC 巨型油船； ULCC 超级油船 Chemical tanker 化学品船 = Product carrier 成品油船 Containerships, including: Conventional containership 常规集装箱船 Hatchcoverless containership 无舱盖集装箱船 Liquified gas carrier, including: LPG 液化石油气船； LNG 液化天然气船 Refrigeration cargo ship(reefer)冷藏船 RoRo ship 滚装船

Barge carrier 载驳船； LASH 载驳船； SEABEE 升降式载驳船

Group 2: Sea and coastal ships, inland waterway ships 近海、沿海和内河船舶

(Cross-channel)ferries(for passengers, cars, or both)渡船 Passenger ships, with the following forms: Conventional liner 常规客班船

Hydrofoil 水翼艇

Hovercraft(air cushion vehicle: ACV)腾气艇、气垫船

Cargo vessels, the subpision is much the same as above.Cargo-passenger ships 货客船

Pleasure boats 游艇

Barges 驳船

Group 3: Subsidiary ships 辅助船舶

Working ships, including: 工程船

Tug 拖轮； Floating crane 浮吊； Dredger 挖泥船

Salvage ship 打捞船； Drilling vessel 钻井船； Pile-driver 打桩船

Pipe line layer 敷管船； cable layer 布缆船； Dike layer 驻堤船

Icebreaker 破冰船； Firefighting ship 消防船；buoy tender 航标船

Research ship 调查船、研究船； Split hopper barge 开体泥驳

Fishing vessel, including: 渔船

Trawler 拖网渔船； Fish factory ship 鱼品加工船；

Seiner 围网渔船

Others

Supply ship(water, fuel oil)供应船

Training ship 训练船 Navy Ships Navy Armament Gun / heavy gun 枪、炮；

Depth bomb / charge 深水炸弹 Mine 水雷；

Torpedo 鱼雷

Missile 弹道；

Armed aircraft 武装飞机 Group 1: War Ships Subgroup 1: Surface combatant ship 水面舰艇 Patrol boat 巡逻艇；

Gun boat 炮艇

Torpedo boat 鱼雷艇；

Guided missile boat 弹道艇 Submarine hunter 猎潜艇；

Frigate 护卫舰 Destroyer 驱逐舰；

Cruiser 巡洋舰

Helicopter carrier 直升机母舰；

Aircraft carrier 航空母舰 Subgroup 2: Undersea ships 水下舰艇 Submarine, pided into: Conventional powered submarine 常规动力潜艇 Nuclear powered submarine 核潜艇 Group 2: Naval Auxiliary Ships Landing ship(boat)登陆舰/艇；

Minehunter(mine-sweeper)扫雷艇 Minelayer 布雷舰；

Combat stores ship 舰队补给船 Ammunition ship 军火船；

Surveying ship 测量船 Commuter boat(traffic boat)交通艇 课文阅读 Part A The development of ship types over the years has been dictated very largely by the nature of the cargo.The various designs can, to some extent, be pided into general cargo, bulk cargo and passenger vessels.这么多年来船型的发展在很大程度上受制于货物的性质。在某种程度上，各种式样可以划分为杂货船、散货船和客船。

The general cargo carrier is a flexible design of vessel which will go anywhere and carry anything.Special forms of the general cargo carrier include container ships, roll-on/roll-off ships and barge carriers.Bulk cargo may be liquid, solid, or liquefied gas and particular designs of vessel exist for the carriage of each.杂货船是一种灵活的船舶式样，它可以去任何地方载任何货物。杂货船的特殊形式包括集装箱船，滚装船和载驳船。散货可以是液态的、固态的或液化气，针对每一种货物运载都存在着特殊形式的船舶。Passenger-carrying vessels include cruise liners and ferries.Many special types of vessel exist which perform particular functions or are developments of particular aspects of technology.These include multi-hull vessels, hydrofoil and hovercraft.运载旅客的船舶包括（定期）旅游船和渡船。也存在许多特殊的船型，它们发挥特定的功能或是一些特定领域技术发展的产物。这些包括多体船，水翼艇和气垫船。

These various ship types will now be examined in further detail.这些各式各样的船型将予以进一步的讨论。

General cargo ships 常规杂货船

The general cargo ships have several large clear open cargo-carrying spaces or holds.One or more separate decks may be present within the holds and are known as “tween decks”.These provide increased flexibility in loading and unloading and permit cargo segregation as well as improved stability.Access to these holds is by openings in the deck known as hatches.杂货船有几个大而宽敞的载货空间或货舱。舱内可能设一层或更多层分离的甲板，它们被称为“间甲板”。这些间甲板增加了装货与卸货的灵活性，有利于分隔货物以及改善稳性。通向这些货舱的入口是在甲板上设置的开口，它们被成为舱口。

Hatches are made as large as strength considerations permit in order to reduce the amount of horizontal movement of cargo within the ship.Hatch covers are, nowadays, made of steel although older vessels used wood.The hatch covers must be watertight and rest upon coamings around the hatch.The coamings of the upper or weather deck hatches are a reasonable height above the deck to reduce the risk of flooding in heavy seas.只要强度方面允许，舱口升得尽可能大，以减少货物在船内的水平运动的幅度。当今舱口盖由钢铁制成，虽然在一些较旧的船上使用木质舱口盖。舱口盖必须水密并坐落在围着开口的舱口围板上。上甲板或露天甲板舱口的围板离甲板有一个合理的高度，以减少在大浪中货舱进水的风险。

Some form of cargo handling equipment is always fitted which may take the form of derricks and winches or deck cranes.Deck cranes are fitted to many vessels since they reduce cargo handling times and manpower requirements.Some ships have a special heavy-lift derrick fitted which may serve one or more holds.某种形式的起货机总装在这种船上，其形式可以是吊杆和绞车或甲板起重机。甲板起重机装在许多船上因为它们能减少货物搬运时间和人力需求。一些船上装有特殊的重型吊杆，可以为一个或几个货舱服务。

A double bottom is fitted along the ship‟s length and is pided into various tanks.These tanks may be used for fuel or lubricating oil, fresh water or ballast sea water.Fore and aft peak tanks are also fitted and may be used to carry ballast or to suitably trim the ship.Deep tanks are often fitted and can be used to carry liquid cargoes or water ballast.The water ballast tanks may be filled when the ship is only partially loaded in order to provide a sufficient draught for stability and total propeller immersion.沿船长方向设置双层底，并将其划分成各种液舱。这些液舱可用作燃油舱或滑油舱，淡水舱或压载海水舱。船上也设置首尾尖舱，可用来装压载水或用来适当地调准纵倾。船上常常设深舱，可用来装载液体货物或压载水。当船舶仅部分装载时，压载水舱可灌水以便为稳性和螺旋桨总浸深提高足够的吃水。There is usually one hold aft the accommodation and machinery space.This arrangement improves the trim of the vessel when it is partially loaded.The range of size for general cargo ships is currently from 2,000 to 15,000 displacement tones with speeds from 12 to 18 knots.住舱和机舱之后通常设一个货舱。这种布置在船舶部分装载时能改善船舶的纵倾。杂货船的尺度范围当前为2000至15000排水吨，速度为12至18节。

Refrigerated cargo ships 冷藏船

The refrigerated cargo ship differs from the general cargo ship in that it carries perishable goods.A refrigeration system is therefore necessary to provide low temperature holds for these cargoes.The holds and the various „tween decks are insulated to reduce heat transfer.The cargo may be carried frozen or chilled and various holds may be at different temperatures according to the cargo requirements.冷藏船与杂货船的不同之处在于装载易变质货物。因为必须设制冷系统为这些货物提供低温货舱。货舱和各层间甲板都作绝缘处理以减少热传递。货物可以冷冻或冷藏运载，而且根据货物的要求各个货舱可以调至不同的温度。

This type of vessel is usually faster than a general cargo ship, having speeds up to 22 knots.It is essentially a cargo liner having set schedules and sailing between fixed terminal ports.Up to twelve passengers may be carried on some of these vessels.这种船通常比杂货船快，具有高达22节的航速。它基本上是一种定期货船，有既定的计划并在固定的港口之间航行。这些船有的可以携带多到12名的旅客。

Container ships 集装箱船

A container is a re-usable box of 2,435 mm by 2,435 mm section, with lengths of either 6,055, 9,125 or 12,190 mm.Container are now used for most general cargoes and liquid-carrying versions also exist.Refrigerated versions are also in use which may have their own independent refrigeration plant or be supplied with cooled air from the ship‟s refrigeration system.集装箱是一只可反复使用的箱子，宽度和高度为2435mmX2435mm，长度6055，9125或12190mm三种。现在集装箱船用于装载大多数杂货，而且也有转载液体的集装箱。冷藏集装箱也在使用，它可以有自己独立的制冷装置或由船舶的制冷系统提供冷气。

The cargo-carrying section of the ship is pided into several holds each of which has a hatch opening the full width and length of the hold.The containers are racked in special frameworks and stacked one upon the other within the hold space.Cargo handling is therefore only the vertical movement of the container by a special quayside crane.Containers may also be stacked on the flush top hatch covers.Special lashing arrangements are used to secure this deck cargo.船舶的载货区划分成几个货舱，每一货舱的舱口大小与货舱的全宽和全长一样。集装箱放在特殊的框架内，并在货舱空间内一只箱子堆在另一只箱子上。因此货物搬运仅仅是用特殊的岸壁起重机使集装箱作垂向运动。集装箱也可以堆放在顶部平坦的舱口盖上。这种甲板货物用特殊的绑扎装置来固定。

The various cargo holds are separated by a deep web-framed structure to provide the ship with transverse strength.The ship structure outboard of the container holds on either side is a box-like arrangement of wing tanks which provides longitudinal strength to the structure.These wing tanks may be used for water ballast and can be arranged to counter the heeling of the ship when discharging containers.A double bottom is also fitted which adds to the longitudinal strength and provides additional ballast space.各个货舱用强框架结构隔开，为船舶提供横向强度。集装箱舱外侧船舶两舷的结构为箱形布置的边舱，为结构提供纵向强度。这些边舱可以用来装压载水，并能安排来抵抗船舶卸箱时产生的横斜。船舶也设双层底，它增加了纵向强度并提供额外的压载空间。

The accommodation and machinery spaces are usually located aft to provide the maximum length of full-boded ship for container stowage.Cargo-handling equipment is rarely fitted, since these ships travel between specially equipped terminals to ensure rapid loading and discharge.Container ship sizes vary considerably, with container carrying capacities from 1,000 to 2,500 TEU‟s or more.The twenty foot equivalent unit(TEU)represents a 20 ft(6,055 mm)“standard” container.Container ships are much faster than most cargo ships, with speeds up to 30 knots.They operate as liners on set schedules between fixed ports.居住舱室和机舱通常位于船尾，以提供最大长度的丰满船体用语储藏集装箱。起货设备很少安装，因为这些船舶行驶在特殊装备的终点港间以确保迅速装卸。集装箱船的尺度变化很大，其集装箱装载能力从1000箱到2500箱或更多。二十英尺相当单元（TEU）代表二十英尺（6055mm）“标准”集装箱。集装箱船比大多数船快得多，速度高达30节。它们作为定期航船按既定计划在固定港口间运营。

Roll-on / roll-off ships 滚装船

This vessel was originally designed for wheeled cargo, usually in the form of trailers.The cargo could be rapidly loaded and unloaded by stern or bow ramps and sometimes sideports for smaller vehicles.The loss of public capacity due to undercarriages and clearances has resulted in many roll-on roll-off vessels being also adapted to carry containers.这种船原先设计用于有轮货物，通常是拖车的形式。这种货物可通过尾或首跳板迅速装卸，有时候小型车辆用舷门。车架下空间和上部间隙损失了装卸容积，因而许多滚装船也设计成适于装载集装箱。

The cargo-carrying section of the ship is a large open deck with a loading ramp usually at the after end.Internal ramps lead from the loading deck to the other „tween deck spaces.The cargo may be driven aboard under its own power or loaded by straddle carriers or fork lift trucks.One or more hatches may be provided for containers or general cargo and will be served by one or more deck cranes.Arrangements may be provided on deck for stowing containers.Some roll-on roll-off(Ro-Ro)vessels also have hatch covers to enable loading of lower decks with containers.Where cargo(with or without wheels)is loaded and discharged by cranes the term lift-on lift-off(Lo-Lo)is used.船舶的装货区域是大而宽敞的甲板，在其尾端通常设置装载坡道。内部坡道由装载甲板通向其他间甲板区域。货物可用自己的动力开上船，也可用跨运车或叉车装上船。为了装运集装箱或杂货，船上可有一个或几个舱口，并配有一台或几台甲板吊车。甲板上也可以布置来堆放集装箱。某些滚装船也时舱口盖，以便在下层甲板上装载集装箱。当货物（有轮或无轮）用起重机装卸时，就用“吊上-吊下”（LO-LO）这一术语。

The ship‟s structure outboard of the cargo decks is a box-like arrangement of wing tanks to provide longitudinal strength.A double bottom is also fitted along the complete length.The accommodation is located aft and also the low-height machinery space.Only a narrow machinery casing actually penetrates the loading deck.Sizes range considerably with about 16,000 dwt(28,000 displacement tonne)being quite common.High speeds in the region of 18~22 knots are usual.货物加班舷侧部分的船体结构是箱形布置的边舱，以提供纵向强度。这种船也在全厂范围内设置双层底。住舱还有低高度的机舱都位于船尾。实际上仅有狭窄的机舱棚穿国装载甲板。尺度变化很大，16000载重吨（28000排水吨）相当普遍。速度通常高达18至22节。

Barge carrier 载驳船

This type of vessel is a variation of the container ship, instead of containers, standard barges are carried into which the cargo has been previously loaded.The barges, once unloaded, are towed away by tugs and return cargo barges are loaded.Minimal or even no port facilities are required and the system is particularly suited to countries with vast inland waterways.Two particular types will be described, the LASH(Lighter Aboard Ship)and the SEABEE.这种船是集装箱船的派生船型，所装载的不是集装箱，而是标准的驳船，驳船中预先装进了货物。驳船一当卸下就被拖轮带走，回来的驳船已装载。这一运输系统很少或甚至不需要港口设备，它特别适合于有大量内陆水道的国家。这里要介绍两种特殊类型，即载驳船（驳船上船）和升降式载驳船。

The LASH ship carries barges, capable of holding up to 00 tonne of cargo, which are 18.75 m(61.5 ft)long, 9.5m(31ft)beam and 3.96 m(13 ft)deep.About eighty barges are carried stacked in holds much the same as containers with some as deck cargo on top of the hatch covers.The barges are loaded and unloaded using a traveling gantry crane capable of lifting over 500 tonne.Actual loading and discharge takes place between extended “arms” at the after end of the ship.The shi structure around the barges is similar to the container ship.The accommodation is located forward whereas the machinery space is one hold space forward of the stern.LASH ships are large, in the region of 45,000 deadweight tones, with speeds in the region of 18 knots.载驳船载运驳船，驳船能装400吨货物，它长18.75m(61.5ft)，宽9.5m(31ft)，深3.96m(13ft)。与集装箱很相像，大约8只驳船放在货舱内，一些作为甲板货物放在舱口盖上面。用一台举力超过500吨的移动式门架起重机来装卸驳船。实际装卸作业在船尾的延伸臂间进行。装驳区周围的船体结构与集装箱船相似。住舱位于船首，而机舱在船尾一个货舱之前。载驳船很大，在45000载重吨左右，速度在18节左右。

The SEABEE is somewhat larger than the LASH ship and carries thirty-eight barges.Each barge may be loaded with up to 1,000 tonne of cargo and is 29.72 m long, by 10.67 m beam and 3.81 m depth.The barges are loaded on board by an elevator located at the stern.They are then winched forward along the various decks.升降式载驳船比载驳船稍微大些，能装载38个驳船；每一驳船可载1000吨货物，它长29.72m，宽10.67m，深3.81m。驳船用位于船尾的一台升降机上船；然后用绞车沿着各层甲板拖向船首。

Deck hatch opening does not exist and the decks are sealed at the after end by large watertight doors.Two „tween decks and the weather deck are used to store the barges.The machinery space and various bunker tanks are located beneath these „tween decks.在甲板上不存在舱口，各层甲板在尾端用大型水密门密封。两层间甲板和露天甲板用来存放驳船。机舱和各种燃料舱位于这些间甲板下方。

The machinery space also extends into the box-like structure outboard of the barges on either side of the ship.The accommodation is also located here together with several ballast tanks.A barge winch room is located forward of the barge decks and provides the machinery for horizontal movement of the barges.The SEABEE is physically about the same size as the LASH ship but with a slightly smaller deadweight of 38,000 tonnes.The speed is similarly in the region of 18 knots.机舱延伸到驳船外侧船舶两舷箱形结构内。住舱也设在此处，还加上几个压载舱。早驳船甲板的前端设置了驳船绞车房，并布置了用于驳船水平运动的机械。升降式载驳船的实体尺度与载驳船大致相同，但载重量略小一些，约38000吨。速度也相似在18节左右。

Despite their being specialist vessels both LASH and SEABEE can be used for other cargoes.Each can be used to carry containers and the SEABEE will also take Ro-Ro cargo.Other variations of barge carriers have been proposed such as the barge carrying catamaran vessel(BACAT).Tug-barge systems have also been considered where the “Ship” is actually a number of linked barges with a separable propulsion unit.尽管它们是专用船，载驳船和升降式载驳船能用于其他货物。每一种船可用来装载集装箱，而升降式载驳船也能携带滚装货。载驳船的其他派生船型已经被提议，如装载双体船的驳船（简称BACAT）。还考虑了“拖轮-驳船”系统，系统中“船舶”实际上是一些相连接的驳船，配备一个可分离的推进单元。

Oil tankers 油船

The demand for crude oil is constantly increasing.Oil tankers, in particular crude carriers, have significantly increased in size in order to obtain the economies of scale.Designations such as ULCC(Ultra Large Crude Carrier)and VLCC(Very Large Crude Carrier)have been used for these huge vessels.Crude oil tankers with deadweight tonnages in excess half a million have been built although the current trend(1985)is for somewhat smaller(100,000~150,000 dwt)vessels.After the crude oil is refined the various products obtained are transported in product carriers.The refined products carried in these vessels include gas oil, aviation fuel and kerosene.对原油的需求在不断地增加。油船特别是原油船已显著地增加了尺度以获得规模经济。诸如ULCC（超级油轮）和VLCC（巨型油轮）这样的名称已用于这些巨大的船舶。载重吨位超过五百万的原油船也已制造，尽管当前（1985）的趋势是稍微小一点的船舶（十到十五万载重吨）。原油经过提炼后，得到的各种产品用成品油船来装载。这些船所装的提炼产品包括汽油，航空燃油和煤油。

The cargo carrying section of the oil tanker is pided into inpidual tanks by longitudinal and transverse bulkheads.The size and location of these cargo tanks is dictated by the International Maritime Organization Convention MARPOL 1973/78.This Convention and its Protocol of 1978 further requires the use of segregated ballast tanks(SBT)and their location such that provide a barrier against accidental oil spillage.An oil tanker when on a ballast voyage must use only its segregated ballast tanks in order to achieve a safe operating condition.油船载货区域用纵横舱壁分割成各个液舱。这些舱的尺寸和位置由国际海事组织公约MARPOL 1973/78所规定。这一公约及其1978年协议进一步要求采用隔离压载水舱（SBT）和其位置必须能提供一道屏障以抵御油泄漏事故。油船在压载航行时必须只使用它的隔离压载水舱以便获得一种安全的运行状况。

The arrangement of a 105,000 dwt crude oil tanker which satisfies these requirements is as follows.The cargo carrying tanks include the seven centre tanks, four pairs of wing tanks and two slop tanks.The segregated ballast tanks include all double bottom tanks beneath the cargo tanks, two pairs of wing tanks and the force and aft peak tanks.The cargo is discharged by cargo pumps fitted in the aft pump room.Each tank has its own suction arrangement which connects to the pumps, and a network of piping discharges the cargo to the deck from where it is pumped ashore.一艘满足这些要求的105，000载重吨原油船，其总布置如下。载货的液舱包括七个中央舱、四对边舱和两个污油舱。隔离压载水舱包括货油舱下的全部双层底液舱、两对边舱以及首尾尖舱。货物由设在后泵房的货油泵卸出。每一油舱都有自己的吸油装置，它与油泵相连，一组管路将货油输送到甲板，再从甲板泵送上岸。

Considerable amounts of piping are visible on the deck running from the after pump room to the discharge manifolds positioned at midships, port and starboard.Hose-handling derricks are fitted port and starboard near the manifolds.The accommodation and machinery spaces are located aft and separated from the tank region by a cofferdam.The range of size for crude oil tankers is enormous, beginning at about 20,000 dwt and extending beyond 500,000 dwt.Speeds range from 12 to 16 knots.在甲板上可以看到大量管路从后泵房走向位于左右舷船中的卸油分配阀箱。软管搬运吊架设在左右舷靠近分配阀箱处。住舱和机舱位于船尾，并用隔离舱与油舱区分开。原油船的尺度范围是巨大的，从二万载重吨直到超过五十万载重吨。速度范围是12至16节。

Product carrier at oil tankers which carry the refined products of crude oil.The cargo tank arrangement is again dictated by MARPOL 73/78.Inpidual “parcels” of various products may be carried at any one time which resulted in several separate loading and discharging piping systems.The tank surface is usually coated to prevent contamination and enable a high standard of tank cleanliness to be achieved after discharge.The current size range is from about 18,000 up to 75,000 dwt with speeds of about 14~16 knots.成品油船是能装载原油炼出产品的油船。同样，其油舱布置受MARPOL 73/78的约束。各种产品的一个个“包裹”可以随时一起装载，这导致了几套分离的装卸管系。油舱表面通常有可防止玷污的涂层，同时也可在卸货后获得高标准的油舱清洁度。目前的尺度范围约18000至75000载重吨，速度为14至16节。

Bulk carriers 散货船

The economies of scale have also been gained in the bulk carriage of cargoes such as grain, sugar and ore.A bulk carrier is a single-deck vessel with the cargo carrying sections of the ship pided into holds or tanks.The hold or tank arrangements vary according to the range of cargoes to be carried.Combination carriers are bulk carriers which have been designed to carry any one of several bulk cargoes on a particular voyage, e.g.ore or crude oil or dry bulk cargo.诸如谷粒、糖和矿砂等货物的大宗运载也赢得了规模经济效益。散装货船是单甲板船，船舶的载货区域划分成几个货舱或液舱。货舱或液舱的布置根据所载货物的种类而变化。兼用船是散货船，它们被设计成在特定的航程中装载几种散货中的任何一种，例如矿砂、油或干散货。In a general-purpose bulk carrier, only the central section of the hold is used for cargo.The partitioned tanks which surround the hold are used for ballast purposes when on ballast voyages.The upper, or saddle, tanks may be ballasted in order to raise the ship‟s centre of gravity when a low density cargo is carried.This hold shape also results in a self-trimming cargo.During unloading the bulk cargo falls into the space below the hatchway and enables the use of grabs or other mechanical unloaders.Large hatchways are a particular feature of bulk carriers since they reduce cargo handling time during loading and unloading.在多用途船散货船上，只有货舱的中央部位用来装货。货舱周围被分隔的液舱在空载时用于压载目的。上边舱或鞍形舱可以装压载，以便在装低密度货物时提高船舶的重心。这种货舱形状也造成货物自我调平。在卸载时，散货落到舱口下方，便于抓斗或其他机械卸货装置的使用。大舱口是散货船的明显特点，因为这可减少装卸作业中货物搬运时间。

An ore carrier has two longitudinal bulkheads which pide the cargo section into wing tanks port and starboard and a center hold which is used for ore.A deep double bottom is a particular feature of ore carriers.Ore, being a dense cargo, would have a very low centre of gravity if placed in the hold of a normal ship.This would lead to an excess of stability in the fully loaded condition.The deep double bottom serves to raise the centre of gravity of the very dense cargo.The behaviour of the vessel is thus much improved.On ballast voyages the wing tanks and the double bottoms ballast capacity.The cross-section would be similar to that for an ore / oil carrier.矿砂船有两道纵壁，从而将载货区域分隔成左右舷的边舱和一个中央货舱；中央舱用语装载矿砂。矿砂船的明显特点是双层底高。矿砂因密度大，如果装在普通船的货舱里其重心会很低。这在满载的状况下会导致稳性过度。高双层底用来提高这种密度货物的重心。船舶的性能因此会改善许多。在压载航行时边舱和双层底提供压载能力。该船的横截面与矿/油船的相似。

An ore / oil carrier uses two longitudinal bulkheads to pide the cargo section into centre and wing tanks which are used for the carriage of oil cargoes.When a cargo of ore is carried, only the centre tank section is used for cargo.A double bottom is fitted but is used only for water ballast.The bulkheads and hatches must be oiltight.矿/油船用两道纵壁将载货区域分隔成中央货舱和左右边舱，边舱用来装油。当装载矿砂时，仅中央舱部位用来装货。船也设置双层底，但只用来装压载水。舱壁和舱口必须油密。

The ore / bulk / oil(OBO)bulk carrier is currently the most popular combination bulk carrier.It has a cargo carrying cross-section similar to the general bulk carrier.The structure is, however, significantly stronger, since the bulkhead must be oiltight and the double bottom must withstand the high density ore load.Only the central tank or hold carries cargo, the other tank areas being ballast-only spaces, except the double bottom which may carry oil fuel or fresh water.矿/散/油船（OBO）是目前最流行的兼用散货船。其载货区横截面与多用途散货船类似。但其结构要强的多，因为其舱壁必须油密且双层底必须承受高密度矿砂的载荷。仅中央液舱或中央货舱装卸货物，但双层底除外，它可装燃油或淡水。

Large hatches are a feature of all bulk carriers, in order to facilitate rapid simple cargo handling.Many bulk carriers do not carry cargo-handling equipment, since they trade between special terminals which have special equipment.Where cargo handling gear is fitted(geared bulk carriers), this does make the vessel more flexible.Combination carriers handling oil cargoes have their own cargo pumps and piping systems for discharging oil.They will also be required to conform to the requirements of MARPOL 73/78.Deadweight capacities range from small to upwards of 200,000 tonnes.Speeds are in the range of 12~16 knots.大舱口是所有散货船的一个特点，以便促使货物搬运既迅速又简单。许多散货船没有起货设备，因为它们在有特殊装备的特定港口之间运行。安装起货机后（自装卸散装货船），确实能使船舶更加灵活。装油的兼用散货船有其自己的货泵和管系用于卸油。它们也被要求满足MARPOL 73/78规定。载重量能力范围从小到二十万吨。速度在12到16节。

Part B（节选）

Liquefied gas carriers 液化天然气船

The bulk transport of natural gases in liquefied form began in 1959 and has steadily increased since then.Specialist ships are now used to carry the various types of gases in a variety of tank systems, combined with arrangements for pressurizing and refrigerating the gas.大宗运输液态形式的天然气始于1959年，从那时起一直稳步增长。现在用专用船将各种形式的气体装在各种液舱系统里，这种系统结合了给气体加压和制冷的措施。

Natural gas is found and released as a result of oil-drilling operations.It is a mixture of methane, ethane, propane, butane and pentane.The heavier gases, propane and butane, are termed “petroleum gases”.The remainder, which consists largely of methane, is known as “natural gas”.The properties, and therefore the behaviour, of these two basic groups vary considerably, thus requiring different means of containment and storage during transportation.天然气是作为石油钻探作业成果被找到和释放的。它是甲烷，乙烷，丙烷，丁烷和戊烷的混合物。较重的气体丙烷和丁烷被称为“石油气”。其余的气体，主要由甲烷组成，被称为“天然气”。这两个基本组合的性质，进而性能，变化相当大，于是在运输过程中要求用不同的手段来容纳和储藏。

Passenger ships 客船

Passenger ships can be considered in two categories, the luxury liner and the ocean-going ferry.The luxury liner is dedicated to the luxurious transport of its human “cargo”.The ocean-going ferry provides a necessary link in a transport system between countries.It often carries roll-on roll-off in addition to its passengers.客船可以分为两类，即豪华班船和远洋渡船。豪华班船是专用于旅客运输的高档交通工具。远洋渡船给国与国之间的运输系统提供了必要的纽带。它不仅运送旅客，还可以运载滚装货。

Luxury passenger liners are nowadays considered to be cruise liners in that they provide luxurious transport between interesting destinations in pleasure climates.The passenger is provided with a superior standard of accommodation and leisure facilities.This result in large amount of superstructure as a prominent feature of the vessel.The many tiers of decks are fitted with large open lounges, ballrooms, swimming pools and promenade areas.Aesthetically pleasing lines are evident with well-raked clipper-type bows and unusual funnel shapes.Stabilizers are fitted to reduce rolling and bow thrusters are used to improve maneuverability.The cruise liner ranges in size up to passenger-carrying capacities of around 1,200(45,000 gt)although a few older large vessels are in service.Speeds are usually high in the region of 22 knots.由于豪华班船在气候宜人的季节里为旅游胜地之间提供高档的客运服务，所以现在通常作为旅游班轮。它为旅客提供了高级的住宿和休闲设施。这就造成这类船舶的显著特征是拥有大量的上层建筑。许多层甲板上装备了大型露天休息室、舞厅、游泳池和散步区。从审美的角度看，这类船舶明显具有充分前倾的飞剪式船首和不同寻常的烟囱造型。稳定器被用来减少横摇，而首部推力器被用来改善操纵性。虽然一些更老、更大的船仍在服役，这类巡航班船的载客能力可大到约1200人（45 000总吨），航速通常高达22节左右。

Ocean-going ferries are a combination of roll-on roll-off and passenger vessels.The vessel is therefore made up in three layers, the lower machinery space, the car decks and the passenger accommodation.A large stern door and sometimes also a lifting bow providing access for the wheeled cargo to the various decks which are connected by ramps.The passenger accommodation will vary according to the length of the journey.For short-haul or channel crossings public rooms with aircraft-type seats will be provided.For long distance ferries cabins and leisure facilities will be provided which may be up to the standard of cruise liners.Stabilizers and bow thrusters are also usually fitted to ocean-going ferries.Size will vary according to rout requirements and speeds are high at around 20~22 knots.远洋渡船是滚装船和客船的一种结合。因此这种船由三层组成，底层的机舱、车辆甲板和旅客住舱。位于船尾的一扇大门，有时还有提升式船首，为滚装货到达由坡道连接的不同层甲板提供了通道。客舱的标准根据旅途的长短有所区别。对于短途或横渡海峡的渡船，公共房间将配备航空式座椅。对于长途渡船，其住舱和休闲设施的豪华程度可达到巡航班船的标准。远洋渡船通常也安装稳定器和首部推力器。船的尺度将根据航线需要而不同，航速则高达20至22节左右。

Unit 2

Ship Performances Lecture 2

The Treatment of Words 专业词汇学习

Spaces Aboard Ships Zone 1: After End(aft peak tank &.Poop)

Aft ballast tank 尾压载舱

Fresh water tank 淡水舱

Steering gear room(tiller room)舵机舱 Zone 2: Machinery Space(engine room)

E.R.double bottom, with the following subpision:

Fuel tank

燃油舱；

Lube tank

滑油舱

Cofferdam

隔离舱；

Void space

空舱

Sea chest

海水箱；

Shaft tunnel 轴隧

E.R.grating

机舱踏格；E.R.Flats

机舱平台

Central control room 集控室；

Workshop 车间

Engine casing

机舱棚；

Funnel

烟囱 Zone 3: Cargo Space

货舱

In case of TK / OBO：

Central tank

中央舱

Wing tank, can be used as: 边舱

Ballast tank

压载舱；

Slop tank 污水舱，污油舱

Double bottom

双层底

In case of BC:

Cargo hold

货舱

Upper hopper tank

上边舱

Lower hopper / bilge tank 下边舱，底边舱

In case of CS:

Wing tank, can be pided vertically:

Torsion box 抗扭箱；

Ballast tank 压载舱

Bilge tank

底边舱

Zone 4: Fore End(fore peak tank & forecastle)

Bow thruster room(if any)侧推舱

Chain locker

锚链舱

Fore ballast tank

首压载舱

Forecastle, can be subpided into: 首楼

Paint room

油漆间

Store(boatswain‟s store)

帆缆舱 Zone 5: Upper Deck

上甲板

Deck house

甲板室

Hatch coaming

舱口围板

Winch control room 绞车控制室

Store

储藏室

Zone 6: Accommodation(living quarters)上层建筑

Poop deck, generally with:

尾楼甲板

Provision room

食品库

Reefer room

冷藏库

Galley

厨房

Crew‟s mess room

船员餐厅

Accommodation deck, generally with: 起居甲板

Air conditioning room 空调机房

Laundry

洗衣机房

Crew‟s room

船员卧室

Officer‟s mess room

高级船员餐厅

Officer‟s room

高级船员卧室

Boat deck, generally with: 救生甲板

Captain‟s room

船长室

Gyro room

电罗经室

Navigation deck(bridge deck), with: 驾驶甲板

Wheelhouse

驾驶室

Radio office

报房

Chart room

海图室

Compass deck

罗经甲板 Terms of Ship Performance 1.Buoyancy 浮力方面 Floating conditions 浮态

Even keel 正浮；

Trim 纵倾 Trim by the bow / stem

首倾 Trim by the stern = stern

尾倾 Hell / list

横倾 Centers

中心

Center of gravity

重心； Center of buoyancy 浮心 Center of floatation 漂心； Metacenter

稳心 Centroid

形心，质心 2.Stability 稳性方面

Transverse / lateral stability 横稳性； Longitudinal stability 纵稳性

Initial / metacentric stability 初稳性

Stability at large angles of inclination 大倾角稳性

Intact stability 完整稳性

Damaged / impaired / flooded stability 破舱稳性 3.Resistance 阻力

Wave-making resistance 兴波阻力；Viscous resistance

粘性阻力 Friction resistance

摩擦阻力；Eddy-making resistance 旋涡阻力 Wave-breaking resistance 破波阻力；Appendage resistance

附体阻力 Wind(age)resistance

风阻力 1．Motion 运动

Ship: Three translation: 三个平移分量

Surging 纵荡；Swaying 横荡；Heaving 垂荡，升沉

Three rotation 三个转动分量

Wave: Head sea(345~15 degrees)

顶浪，迎浪

Bow sea(15~75, 285~345)

首斜浪

Athwart sea(75~105, 255~285)

横浪

Quartering sea(105~165,195~255)尾斜浪

Stern sea(165~195 degrees)

尾浪 2．Others Insubmersibility

不沉性；

Rapidity

快速性 Endurance

续航力；

Maneuverability 操纵性 Course keeping

航向保持性；Sea-keeping

耐波性 Sea-worthiness

适航性 课文阅读 Part A Hydrostatic curves 静水力曲线

It has been shown how the displacement of a ship and the position of the centre of buoyancy can be calculated and also how the position of the metacentres and the center of floatation can be determined.It is customary to calculate all these quantities for about six or seven waterlines parallel to the base and spaced one metre(3 or 4 ft)apart.The results so obtained are plotted in a diagram with draught measured vertically.The curves drawn in this way are called “hydrostatic curves”.已经说明船舶的排水量和浮心位置是如何计算的以及稳心和漂心位置是如何确定的。习惯上所有这些数据都按六至七条水线来计算，这些水线与基线平行且相隔一米（3或4英尺）。如此得到的结果画在一张图上，吃水垂直量取。这样绘制的曲线称为“静水力曲线”。Two curves of displacement are shown.One is called the “moulded displacement” and it is the displacement obtained to the moulded line of the ship between perpendiculars.To obtain the extreme displacement it is necessary to add on to this shell displacement, the displacement of the cruiser stern and bulb forward, if fitted, and in the case of multiple screw ships the displacement of the bossing enclosing the shafting.Sometimes the displacement of the rudder and propeller and shafting are included in the extreme displacement.两条排水量曲线需要说明。一条叫做“型排水量”曲线，它是根据两垂线间的船体型线得出的排水量。要得到最大排水量就必须在型排水量的基数上再加上外板排水量，如果没有巡洋船尾和球鼻首时还应该加上这两者的排水量，以及如果是多螺旋桨船时尚应加上包封轴系的轴壳的排水量。有时舵、螺旋桨和桨轴的排水量也计入最大排水量。

It is also important to correct the position of the centre of buoyancy for these items, and this would apply particularly to the longitudinal position of the centre of buoyancy since the volume of such items as bossing can have a major effect.就这些项目来修正浮心位置也很重要，这特别适用于浮心的纵向位置，因为如轴壳这类项目可能对排水体积有重要影响。

With regard to the displacement of the shell, this is determined by first of all calculating the wetted surface area.This area when multiplied by the mean thickness of the shell plating will give the volume displaced by the shell.The wetted surface area is not easy to calculate since the outside surface of a ship has double curvature.It can be approximated to by taking girths round the various sections and then applying Simpson‟s rule to find the area.The procedure ignores the curvature of the hull surface in the fore and aft direction(the “obliquity effect” as it is sometimes called), but this is often not of great magnitude.关于壳板的排水量。这首先要通过计算湿表面面积来确定。这一面积上外板的平均厚度可得到壳板的排水体积。但湿表面面积不是容易计算的，因为船体外表面具有双向曲度。这可以近似地量取各横剖面的围长然后用辛普生法得出湿面积。这一过程忽略了船体表面首尾方向的曲度（有时也称作“倾斜效应”），但通常影响程度不大。

Shell displacement represents only a small percentage of the total displacement of a ship but is of sufficient magnitude to justify its inclusion in the calculation of the displacement.In a large modern vessel it could amount to many hundreds of tonnes.船壳板排水量仅占有船舶总排水量很小的百分比，但其数值足够证明将其纳入排水量计算是正确的。大型现代船舶这一数值可能高达几百吨。

There is a curve which gives the increase in displacement for unit increase in draught.If A is the area of the waterplane at which the ship is floating, then for unit increase in draught the volume added is Ax1 assuming the ship to be wall sided in the neighbourhood of the waterline.It follows that increase in displacement = ρgA.When imperial unit are used the weight per unit volume of sea water is given as 1/35 ton/ft3, so that increase in displacement = A/35, and A in square feet, which may be called the “ton per foot immersion”.As this is quite a large quantity it was usually pided by 12 to give “ton per inch immersion”.Therefore: TPI = A/420 for sea water When using SI units it is probably more convenient to leave this quantity in the form given above, i.e., ρgA where ρ is the density in kg/m3, g is the acceleration due to gravity and A is the waterplane area in m2.For ρ = 1 025 kg/m3 and g = 9.81 m/s2: Increase in displacement per metre increase in draught =1 025 X 9.81 X 1 X A = 10 055 AN =0.010 055 A MN For 1 cm immersion this would become 0.000,100,55 A MN.有一根曲线给出单位吃水增加与排水量增加的关系。若A是船舶漂浮处的水线面面积，则单位吃水增加时排水体积的增加为AX1，假设船舶水线附近的舷侧是直壁状的。于是排水量增加 = ρgA。如果使用英制，每单位体积海水的重量给定为1/35 ton/ft3，那么排水量增加 = A/35，其中A 的单位是平方英尺，这一增量称作“浸水英吨/英尺”。鉴于这是一个很大的数量，通常将其除以12给出“浸水英吨/英尺”。因此：对海水浸水英吨/英寸= A/ 420。

3使用国际单位时，保留上面给出的形式可能更方便，即ρgA，式中：ρ是密度单位为kg/m，g是重力加速度而A是水线面面积，单位为m2。当g = 9.81 m/s2时：吃水每增加1米时排水量增加 = 1 025 X 9.81 X 1 X A = 10 055 AN 对于每厘米浸水这变成0.000,100,55 A MN。

The increase in displacement per unit increase in draught is useful in approximate calculations when weights are added to the ship.The weight added pided by this quantity gives the parallel sinkage of the ship.The calculation is only reasonably correct for the addition of relatively small weights, since the increase in displacement per unit increase of draught varies with the draught.当船舶增加重量时，单位吃水增加后排水量的增加在近似计算中是有用的。增加的重量除以这一数值可给出船舶的平行下沉量。只有当增加的重量相对较小时这种计算才有合理的正确性，因为单位吃水增加后排水量增加将随吃水而变化。

Hydrostatic curves are most useful in working out the end draughts and the stability of a ship as represented by metacentric height in various conditions of loading.This is done for all the calculations which have been discussed.The input data required consist of ordinates at various waterlines defining the form of a ship.When this is put into the computer the program calculates all the quantities necessary for plotting hydrostatic curves.It can be done in a very short space of time, whereas in the days of hand calculations the production of a set of hydrostatic curves required about two man weeks.静水力曲线在求得船舶最终吃水和稳性的过程中非常有用；稳性是用各种装载状态下的稳心高度来表示的。我们已讨论过的全部计算都是这样做的。所需的输入数据由定义船舶形状的各水线的坐标组成。当输入计算机后程序计算绘制静水力曲线所需的全部数值。这能在很短的时间内完成，而在手算的年代要算出一套静水力曲线要花约一人两周工作量。

Ship resistance 船舶阻力

A ship when at rest in still water experiences hydrostatic pressures which act normally to the immersed surface.It has already been stated when dealing with buoyancy and stability problems that the forces generated by these pressures have a vertical resultant which is exactly equal to the gravitational force acting on the mass of the ship, i.e., is equal to the weight of the ship.If the forces due to the hydrostatic pressure are resolved in the force and aft and the transverse directions it will be found that their resultants in both of these directions are zero.Consider what happens when the ship moves forward through the water with some velocity V.The effect of this forward motion is to generate dynamic pressures on the hull which modify the original normal static pressure and if the forces arising from this modified pressure system are resolved in the fore and aft direction it will be found that there is now a resultant which opposes the motion of the ship through the water.If the forces are resolved in the transverse direction the resultant is zero because of the symmetry of the ship form.置于静水中的船舶经受着静水压力，它垂直作用于船体的浸湿表面。早已经说过，在处理浮力和稳性问题时，这些压力产生的力有一个垂向合力，它与作用在船舶质量的重力刚好相等，也即等于船舶的重量。如果将静水压力产生的力沿着首尾和横向分解，结果会发现合力在这两个方向上都为0。考虑一下船舶以某一速度V在水中前进时会发生什么。这一向前运动的结果是将在船体上产生动态压力，这种动态压力改变了原来的静态正压力；如果将改变后的压力系统所产生的力在船的前后方向进行分解，那么可以发现这时有一个合力，它与船在水中运动的方向相反。如果这些力沿横向分解，因船体形状的对称性合力为0。

Another set of forces has to be considered when the ship has ahead motion.All fluids possess to greater or less extent the property known as viscosity and therefore when a surface such as the immersed surface of a ship moves through water, tangential forces are generated which when summed up produce a resultant opposing the motion of the ship.The two sets of forces both normal and tangential produce resultants with act in a direction opposite to the direction in which the ship is moving.This total force is the resistance of the ship or what is sometimes called the “drag”.It is sometimes convenient to split up the total resistance into a number of components and assign various names to them.However, whatever names they are given the resistance components concerned must arise from one of the two types of force discussed, i.e., either forces normal to the hull surface or forces tangential to that surface.船舶向前运动时还要考虑另一组力。所有流体或多或少有一性质叫粘性，因此当如船体浸湿表面那样表面在水中前进时就产生了切向力，将其累加起来便产生了与船舶运动反向的合力。这两组垂向和切向的力产生的合力其方向与船舶运动的方向相反。这一总力就是船舶的阻力或有时叫做“拖力”。有时为了方便将总阻力分成许多分量并给予不同的名称。然而不管给什么名称，有关的阻力分量必定来自讨论过的两种力，即与船体表面不是垂直就是相切的力。

The ship actually moves at the same time through two fluids of widely different densities.While the lower part of the hull is moving through water the upper part is moving through air.Air, like water, also possesses viscosity so that the above water portion of a ship‟s hull is subjected to the same two types of forces as the underwater portion.Because, however, the density of air is very much smaller than water the resistance arising from this cause is also very much less in still air conditions.However, should the ship be moving head on into a wind, for example, then the air resistance could be very much greater than for the still air condition.This type of resistance is, therefore, only a limited extent dependent on the ship speed and will be very much dependent on the wind speed.实际上船舶同时在两种密度极其不同的流体中移动。当船体下部在水中移动时，其上部在空气中移动。空气如水一样也具有粘性，因此船体水上部分与水下部分一样也经受着同样的两种力。然而，因为空气的密度比水小很多，这一原因引起的阻力在静水空气状态下也非常小。但是举例来说，假如船舶迎风行驶，那么空气阻力会比静止空气状态下大许多。因此，这种阻力程度有限，取决于船舶速度，也在很大程度上取决于风速。

Types of resistance 阻力类型

It was stated above that it is sometimes convenient to split up the total resistance into a number of components, these will now be considered.上面说过，有时为了方便将总阻力分为许多分量，现在来讨论这些分量。

The redistribution of normal pressure around the hull of the ship caused by the ahead motion gives rise to elevations and depressions of the free surface since this must be a surface of constant pressure.The result is that waves are generated on the surface of the water and spread away from the ship.Waves possess energy so that the waves made by the ship represent a loss of energy from the system.Looked at in another way the ship must do work upon the water to maintain the waves.For this reason the resistance opposing the motion of the ship due to this cause is called ”wave-making resistance”.With deeply submerged bodies the changes in the normal pressure around the hull due to ahead motion have only a small effect on the free surface so that the wave resistance tends to be small or negligible in such cases.船舶前进运动造成的船体周围正压力的重新分布引起自由液面的升起和降落，因为睡眠必须是常压表面。其结果是在水面产生了波浪并由船舶向外伸展。波浪具有能量，因此船舶造成的波浪代表了系统中能量的损失。从另一角度看，船舶必须对水做功以维持波浪。根据这一道理，由这个原因引起的抵抗船舶运动的阻力称作“兴波阻力”。对于深潜的物体由前进运动造成壳体周围正压力的变化对自由表面仅有细微影响，因而波浪阻力变得很小或在这种情况下可以忽略。

The resistance arising due to the viscosity of the water is appropriately called “viscosity resistance” or often “frictional resistance”.The thin layer of fluid actually in contact with the immersed surface is carried along with it but because of viscosity a shear force is generated which communicates some velocity to the adjacent layer.This layer is turn communicates velocity to the next layer further out from the hull and so on.It is clear then that there is a mass of fluid which is being dragged along with the ship due to viscosity and as this mass requires a force to set it in motion there is a drag on the ship which is the frictional resistance.The velocity of the forward moving water declines in going outwards from the hull and although theoretically there would still be velocity at infinite distance the velocity gradient is greatest near the hull and at a short distance outwards the forward velocity is practically negligible.Forward velocity is therefore confined to a relatively narrow layer adjacent to the hull.This layer is called the “boundary layer”.The width of the layer is comparatively small at the bow of the ship but thickens in going aft.由于水的粘性引起阻力被确当地称为“粘性阻力”或通常叫做“摩擦阻力”。和浸湿表面实际接触的一薄层流体被表面夹带，但因为粘性而产生了剪力，剪力将一部分速度传给临近的薄层。这一薄层又将速度传给下一离船体更远的薄层，等等。那么很清楚有一定质量的流体因粘性被船体拖者走；因为这一质量要求外力使其运动，船舶就有阻力，叫做摩擦阻力。由船体向外，水向前运动的速度下降；尽管从理论上讲在无限远处水还有速度，速度梯度在靠近船体处最大而在一个短距离之外前进速度实际上可以忽略。因此前进速度仅限于船体附近相对很窄的一层。这一层称作“边界层”。这一层的宽度在船首相比较小，但往后会加厚。

The actual thickness of the boundary layer is indeterminate but the point where the forward velocity has fallen to about 1% of what it would be if the water were frictionless is considered to be the outer extremity of the boundary layer.Thus, where the velocity of the water relative to the body is 0.99 of what it would be at the same point if the water were frictionless would be the outer edge of the boundary layer.边界层的实际厚度是不能确定的；但是，如果水没有摩擦力时边界层水将随船前进，那么水的前进速度下降了1%，这一处就被认为是边界层的外沿。于是水的某处相对于物体的速度为99%的同一点速度（假如水没有摩擦）时，该处就是边界层的外缘。

Theoretical investigations on flow around immersed bodies show that the flow follows the type of streamline pattern.However, where there are sharp changes of curvature on the surface of the body, and partly due to the viscosity of the fluid, the flow separates from the surface and eddies are formed.This separation means that the normal pressure of the fluid is not recovered as it would be according to theory and in consequence a resistance is generated which is often referred to as “eddy-making resistance”.This type of resistance, like wave-making resistance, arises from a redistribution of the normal pressure around the hull in contrast to the frictional resistance which arises because of tangential viscous forces.对沉浸物体周围水流的理论研究表明水流呈现流线形式。但是，在物体表面有曲度突变之处，部分是流体粘性缘故，水流从表面散开而形成旋涡。这样的散开意味着流体的正压力没有像理论那样会恢复，结果产生了阻力，它常被称为“旋涡阻力”。这一形式的阻力，像兴波阻力，是由船体周围的正压力重新分布而引起的；与摩擦阻力相左，它是因切向粘性力引起的。

The fourth type of resistance is that due to the motion of the above-water form through the air, as has already been mentioned, and could consist of a combination of frictional and eddy resistance.第四种阻力是船体水上部分在空气中运动引起的那种阻力，如早已提到的，可由摩擦阻力和旋涡阻力联合构成。

Part B（节选）

The Propulsion device 推进设备

The force needed to propel the ship must be obtained from a reaction against the air, water or land, e.g., by causing a stream of air or water to move in the opposite direction.The sailing ship uses air reaction.Devices acting on water are the paddle wheel, oar and screw propeller.Reaction on land is used by the punt pole or the horse towing a barge.推进船舶所需的力必须由空气、水或陆地的反作用力而获得，例如，靠产生气流或水流朝相反方向运动。帆船利用空气反作用力。作用于水的设备如明轮、橹和螺旋桨。陆地反作用力的利用靠撑船杆（蒿）或马匹拖驳船。

For general applications, the land reaction is not available and the naval architect must make use of water or air.The force acting on the ship arises from the rate of change of momentum induced in the fluid.对于一般应用，陆地反作用力不可利用，造船师必须利用水和空气。作用在船上的力来自流体中产生的动量变化率。

Consider a stream of fluid, density ρ, caused to move with velocity v in a “tube”, of cross-sectional area A.Then the mass of fluid passing any section per second = ρAv and the momentum of this fluid = mv = ρAv2.Since fluid is initially at rest, the rate of change of momentum =ρAv2.考虑一股流体，密度ρ，在截面积为A的“管子”里被驱动，速度为V。那么，在管子任何一段通过的流体质量 =ρAV且这一流体的动量= mv = ρAV。然流体初始为静

2止，那么动量变化率=ρAV2。

In a specific application, the force required is governed by the speed desired and the resistance of the ship.Since the force produced is directly proportional to the mass density of the fluid, it is reasonable to use the more massive of the two fluids available, i.e., water.If air were used, then either the cross-sectional are of the jet must be large or the velocity must be high.在特定的应用中，所需的力由希望达到的速度和船舶的阻力来决定。因为产生的力直接与流体的质量密度成比例，所以利用现成的两种流体中的更重者是合理的，就是利用水。假如使用空气，那么不是喷流的截面积必须很大，就是速度必须很高，两者取其一。

This explains why most ships employ a system by which water is caused to move aft relative to the ship.A variety of means is available for producing this stream of water aft, but by far the most commonly used is the screw propeller.这说明了为什么大多数船舶采用一种系统驱使水流朝船的后方运动。有各种各样的方法可用来产生这种向后的水流，但到目前为止最广泛使用的还是螺旋桨。

The screw propeller Basically the screw propeller may be regarded as part of a helicoidal surface which, in being rotated, “screws” its way through the water driving water aft and ship forward.Some propellers have adjustable blades – they are called controllable pitch propeller – but by far the greater majority of propellers have fixed blades.The ones we are concerned with here are fixed pitch propellers.基本上螺旋桨可以认为是螺旋面的一部分，当它旋转时（螺旋桨）一路往水里“拧”，将水往后推，而使船向前进。一些螺旋桨有可调节的叶片，它们称作可调螺距螺旋桨，但到目前为止大多数螺旋桨有固定的螺距。这里我们关心的是固定螺距螺旋桨。

Propellers can be designed to turn in either directions in producing an ahead thrust.If they turn clockwise when viewed from aft, they are said to be right-handed;if anticlockwise, they are said to be left-handed.In a twin screw ship, the starboard propeller is normally right-handed and the port propeller left-handed.They are said to be outward turning and this reduces cavitation.螺旋桨可以设计成在产生向前推力时朝两个方向旋转。从后面往前看，如果它们顺时针转，就称为右旋，如果逆时针转，就称为左旋。在双桨船上，右舷桨通常是右旋的而左旋桨是左旋的。这一对桨叫做外旋，这样可减少空蚀。

Considering each blade of the propeller, the face is the surface seen when viewed from aft, i.e., it is the driving surface when producing an ahead thrust.The other surface of the blade is called the back.The leading edge of the blade is that edge which thrusts through the water when producing ahead thrust and the other edge is termed the trailing edge.现在考虑螺旋桨的每片桨叶，叶面是从后面往前看时所见的表面，也即产生向前推力时的驱动面。叶片的另一面称作叶背。叶片的导边是在产生向前推力时挤进水里的那边，而另外一边叫做随边。

Other things being equal, the thrust developed by a propeller varies directly with the surface area, ignoring the boss itself.This area can be described in a number of ways.