船体的总布置 general arrangements 球扁钢 blub plate 边界层 boundary layer 舭龙骨 bilge keel 空泡水孔 进速系数advance coefficient
应力集中 stress concentration 剖面模数 section modulus 阻力增额augment of resistance Yaw 首摇 sway 横荡 roll 横摇pitch 纵摇 surge 纵荡heave垂荡
1、The draught at which a ship floats is simply the distance from the bottom of the ship to the waterline.
船舶飘浮时的吃水简单地讲是指船底到水线的距离
2、If the draught at the after end is greater than that at the fore end the ship is trimmed by the stern and if the converse is the case it is trimmed by the bow or by the head. 如果船舶尾吃水大于船首吃水，那么该船为尾倾。反过来，首吃水大于尾吃水，则为首倾
3、Freeboard has an important influence on the seaworthiness of a ship .The greater the freeboard the greater is the above water volume ,and this volume provides reserve buoyancy ,assisting the ship to rise when it goes through waves .The above water volume can also help the ship to remain afloat in the event of damage .It will be seen later that freeboard has an important influence on the range of stability .Minimum freeboards are laid down for ships under International Law in the form of Load Line Regulations.
干舷对船舶适航性有重要影响。干舷越大则水线以上体积就越大。该体积提供了储备浮力当船舶在波浪中航行时帮助船舶漂浮，船舶受损时水线以上体积还帮助船舶保持漂浮性。后面还会看到干舷对船舶稳性也有重要影响。在国际载重线合约中对船舶最小干舷作了规定。
4、Consider first a set of planes perpendicular to the centre line of the ship .Imagine that these planes intersect the ship form at a number of different positions in the length.，the sections obtained are called “body sections” 首先考虑垂直于船纵中线的一组平面。假想这些平面在船长的不同展位上与船体为表面相交。因此得到的剖面称为横剖面
Suppose now that a series of planes parallel to the base and at different distances above it are considered .The sections obtained by the intersection of these planes with the surface of the ship are called 'waterlines'or sometimes 'level lines'.
假设有一些列平面与基平面平行，并考虑每个平面距基平面的不同距离。这些平面与 船体外表相交而得到的剖面称为水线
A third set of sections can be obtained by considering the intersection of a series of vertical planes parallel to the centre line of the ship with the outside surface .The resulting sections are shown in a view called the 'sheer profile'.
第三组剖面由一些列平行于船舶纵中面的平面与船体表面相交而得到。这些剖面的视图称为纵剖面图 5、The influence of block coefficient on the shape of the hull form is that in ships with high values of this coefficient considerable parallel middle is likely to be found and the slopes of the waterlines at the ends are steep. 影响方形系数的形状的船型，在船舶与高度值这个系数相当的平行中可能会被发现和斜坡的吃水线的两端是陡峭的。
6、When the metacenter is above the center of gravity ,there is a positive righting moment formed when the ship is inclined ,and the ship is in stable equilibrium. 当稳心位于重心之上，那么船舶倾斜时就有复原力矩，船舶处于稳定平衡。 7、Resistance to steady forward motion has four components:(1)friction between the water and the hull surface,(2)energy expended in creating the wave system caused by the hull,(3)energy put into eddies shed by the hull and its appendages,and(4)resistance by the air to above-water parts of the ship.
匀速向前运动的阻力有四个组成：1、水与船体表面的摩擦，2、由船体兴波引起的能量消耗，3、由于船体和附体（例如舵）引起的漩涡而消耗的能量，4、船体水面以上的空气阻力。 8、(1)when the pitch varies between leading and following edges ,the propeller will be adaptable to a greater range of ship speeds and(2)when the pitch varies between root and tip ,the propeller take advantage of the variation in velocities of the wake current around the propeller.OOOOOO （1）当螺距在导边和随边间变化时，那么螺旋桨可适应一个较大范围的船速（2）螺距从叶根到叶稍变化时，那么螺旋桨具有适应桨周围的半流的优点。前者修正延伸到推进效率的范围，而后者增加了推进效率的峰值。
9、After the weight and buoyancy curves have been determined ,the subsequent procedure is straightforward .The net-load curve is obtained by merely subtracting the buoyancy values from the weight values at selected intervals along the length and plotting the resulting difference at each location .This curve is then integrated by approximate means to obtain the shear curve ,which in turn is integrated in a similar manner to obtain the bending-moment curve.
体重和浮力曲线已经确定后,随后的过程是非常简单的。net-load曲线所获得的仅仅是减去浮力值权值,在选定的间隔沿长度和策划产生的差异在每一个地点。这条曲线的近似然后整合手段获取剪切曲线,进而集成在一个相似的方式来获得bending-moment曲线。
10、Maneuvering at very low speeds is a special problem ,since low water velocity means insufficient lift developed by the rudder .If the rudder is positioned directly behind a propeller ,then a few seconds of high propeller speed can develop lift sufficient to push the stern sideways before generating significant forward motion of the hull .Pushing the stern sideways is tantamount to changing the direction of the hull ,but this expedient is often not sufficient for low-speed maneuvering . 在低速下的操纵性是一个特殊的问题，因为低速情况下意味着由舵产生的升力不足。如果舵安装在螺旋桨正后方，那么在数秒钟之内的连续剧高速旋转可以产生足够的升力去推动船尾，却未能产生明显的向前的运动。侧向推动船尾等于改变船体航向，但这只是权宜之计，对于低速操纵时常常是不够的 11．
汝德比较定律：
如果两艘几何相似船型以相关速度航行（即速度与长度的平方根成比例），那么单位排水量的剩余阻力相同。
12、The first is parts manufacturing using raw materials to manufacture individual parts .The purchasing and handling of components can be considered to be a part of this lowest manufacturing level .The next manufacturing level involves the joining of parts and\\or components to form subassemblies or units .These small collections of joined parts are then combined in the third manufacturing level to form hull blocks .Hull blocks are commonly the largest sections of ships built away from the final building site .Erection ,the final manufacturing level ,involves the landing and joining of blocks at the building site .
第1个是部件制造，用原材料（如钢板、型材、管件、板状金属和缆索）生产单独的部件，构件的采购与操作也可认为是这个低层次的一部分。第2个层次是将构件或/和部件连接在一起，建成组件或单元。第3个层次是将这些小的组件或单元组装或船体分段，船体分段通常是在最终建造地点之外的最大的船体部分。最后的层次是检成船舶，包括在建造地点（如下水船台、草式船坞、干船坞）的合拢。
