Chapter 1 Ship Design（船舶设计）Lesson 2 Ships Categorized（船舶分类）2.1 Introduction（介绍）The forms a ship can take are innumerable. 一艘船能采用的外形是不可胜数的A vessel might appear to be a sleek seagoing hotel carrying passengers along to some exotic destination; a floating fortress bristling with missile launchers; 。
or an elongated box transporting tanks of crude oil and topped with complex pipe connections. 一艘船可以看做是将乘客一直运送到外国目的地的优美的远航宾馆。
竖立有导弹发射架的水面堡垒及甲板上铺盖有复杂管系的加长罐装原油运输轮None of these descriptions of external appearance, however, does justice to the ship system as a whole and integrated unit所有这些外部特点的描述都不能说明船舶系统是一个总的集合体self-sufficient,seaworthy, and adequately stable in its function as a secure habitat for crew and cargo. ——船员和货物的安全性功能：自给自足，适航，足够稳定。
This is the concept that the naval architect keeps in mind when designing the ship and that provides the basis for subsequent discussions, not only in this chapter but throughout the entire book.这是一个造船工程师设计船舶使必须记住的、能为以后讨论提供根据的观念，不仅涉及本章也贯穿全书。
In order to discuss naval architecture,it is helpful to place ships in certain categories. For purposes of this text, ships are classified according to their means of physical support and their designed purposes.将船舶分成一些特定的种类来讨论造船工程是有好处的。
本文的目的就是根据船舶物理支撑方式和设计目的来将它们分类。
2.2 Ships Typed According to Means of Physical Support（根据物理支撑方式来分类）The mode of physical support by which vessels can be categorized assumes that the vessel is operating under designed conditions- Ships are designed to operate above, on, or below the surface of the sea, so the air-sea interface will be used as the reference datum.船舶按物理支撑的分类方式假设，船舶是在设计工况的条件下航行。
船舶预定在海面上，海面中或海面以下航行，因此使用空气与水的接触面作为基准面。
Because the nature of the physical environment is quite different for the three regions just mentioned, the physical characteristics of ships designed to operate in those regions can be diverse.由于上面提到的三个区域中物理环境的本质相差很大，所以那些区域中的船的物理特性也不同。
Aerostatic Support（空气静力支撑）There are two categories of vessels that are supported above the surface of the sea on a self-induced cushion of air. These relatively lightweight vehicles are capable of high speeds,since air resistance is considerably less than water resistance, and the absence of contact with small waves combined with flexible seals reduces the effects of wave impact at high speed. 有两种靠自身诱导的气垫浮于海面上的船。
这些重量相对轻的船能够高速航行，这是因为空气阻力比水阻力小得多，而且船舶高速航行时，弹性密封圈没有与小波浪接触，因而降低了了波浪冲击的影响。
Such vessels depend on lift fans to create a cushion of low-pressure air in an underbody chamber. 这种船依靠升力风扇在船体水下部分产生了低压气垫。
This cushion of air must be sufficient to support the weight of the vehicle above thewater surface.这种空气气垫必须足够支撑水面上方船的重量。
The first type of vessel ha.s flexible skirts that entirely surround the air cushion and enable the ship to rise completely above the sea surface.第一种船有完全围绕在气垫周围并且能够使船完全漂浮在水面以上的弹性围裙。
This is called an air cushion vehicle (ACV) ,and in a limited sense it is amphibious.它被称为气垫船（ACV），某种有限的程度上适用于两栖。
The other type of air-cushion craft has rigid side walls or thin hulls that extend below the surface of the water to reduce the amount of air flow required to maintain the cushion pressure. 另一种气垫船带有刚性侧壁，且有延伸到水下能够减小空气流量的瘦船体，该气流用来维持气垫压力。
This type is called a captured-air-bubble vehicle (CAB).这种类型船称为束缚气泡减阻船It requires less lift-fan power than an ACV, is more directionally stable and can be propelled by water jets or supercavitating propellers. 相对于 ACV 来说，它需要较低的升力风扇动力,航向稳定性更好，并且能使用喷水推进器和超空泡螺旋桨。
It is not amphibious, however, and has not yet achieved the popularity of the ACVs, which include passenger ferries, cross-channel automobile ferries, polar-exploration craft, landing craft, and riverine warfare vessels.但是，它不是两栖用途的，也还没有 ACVs 那么广的适用范围，适用范围包括游客渡轮，横越海峡车客渡轮，极地考察船，登陆舰及内河舰艇。
Hydrodynam ic Support（水动力支撑）There are also two types of vessels that depend on dynamic support generated byrelatively rapid forward motion of specially designed hydrodynamic shapes either on or beneath the surface of the water. 也有两种类型船，它们依赖通过船的相对高速前进运动来产生动力支持，这种船型的水上和水下部分的形状都经过特殊设计。
A principle of physics states that any moving object that can produce an unsymmetrical flow pattern generates a lift force perpendicular to the direction of motion. 一个物理定理这样陈述：任何运动的物体都能造成不均匀的流态，产生一个垂直于运动方向的升力。
Just as an airplane with (airfoil) produces lift when moving through the air, a hydrofoil located beneath the surface and attached by means of a surface piercing strut, can dynamically support a vessel s hull above the water.正如装有空气翼的飞机在空气中移动时气翼上能产生一个升力一样，位于水面以下且其上固定有穿透水面的柱体的水翼，能够动态支撑水面以上的船体。