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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.
船舶的设计包括对船型特征，
尺
度比和
比例的选择以及一些非约束条件的选择和那些不受船舶设计师控制的外部环境决定
的约束
条件的选择。
Each new ship should do some
things better than any other ship.
每一新设
计的船舶都应有一些在其他船舶中找不到的试用其本身的独到之处。
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.
这种优势必须在设计的发展演化中
，在使用最合适的材
料
,
达到最佳的工
艺质量中
,
以及应用船舶海洋工程的基本原理中得以发展。
As
ships
have
increased
in
size
and
complexity,
plans
for
building
them
have
became
mare
detailed and more varied.
随着
船舶发展的大型化和复杂化，
船舶的建造方案也变得多变而且
越
发复杂。
The intensive research since the
period just prior to World War 2 has brought about
many technical advances in the design
of ships.
二战之前的深入研究带来了船的设计方面的很
多技术进步。
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.
这
些进步主要是因为新型焊接技术的出现，主要推进
装置的发展，电气设备的革新，和新型
材料和设计方案的应用。
All
ships
have
many
requirements
which
are
common
to
all
types,
whether
they
are
naval,
merchant, or special-
purpose ships.
无论是海船、商船还是特殊用途船，所有船舶都必须满
足
一些最近本的要求。
The first of such
requirements is that the ship must be capable of
floating
when carrying the load for
which it was designed.
第一个这种必要要求就是船舶在装载
情况下
必许能保证浮性。
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.
船舶之所
以能浮在水面上是因为它的水下部分排开了等重的水，这些水对传播有一个向上的反作用
力。这个反作用力就叫做浮力，与浮力相等的船舶排开水的重量产生的力就叫做排水量。
Displacement is equal to the underwater volume
of the ship multiplied by the density of the water
in
which
it
is
floating.
排水量等
于船舶的水下体积乘以其所在水面的水的密度。
When
floating
in
still
water,
the
weight
of
the
ship,
including
everything
it
carries,
is
equal
to
the
buoyancy or displacement.
当船舶
静止在水面上时，
船舶的重量
（包括所有载货量和备品在内）<
/p>
于浮力或者排水量是相等的
The
weight of the ship itself is called the light
weight.
船舶自身
的重量叫做空船重量
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.
空船重
量包括船舶外壳钢料重量，
机电设备重量，
配件重
量，
推进装置重量，
管路和通风设备重量，
货物装卸装置重量和其他为保证船舶操作性的物
品的重量。
The load which the ship carries
in addition to its own weight is called the
deadweight.
船舶总重量中除去船舶自身重量，由货物产生的重量叫做载重
量。
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.
载重
量包括货物，游客，船员和自身物品和备品，淡水，为蒸汽
推进装置准备的炉水，和其他一
些可能是船舶国际航行的载重量
The sum of all
these weights plus the lightweight of the ship
gives the total displacement; that is <
/p>
这些所有重量加上空船重量的总和是船舶的排水量，公式
如下：<
/p>
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.
船舶设计师要做的第一件事就是决定船舶的重量和大小，
决定对吨位已选定的船能够提
供足
够浮力的合适的船体外形
Owner
’
s
requirements
船东要求
Ships are
designed, built, and operated to fulfill the
requirements and limitations specified by
the operator and owner.
船舶的设计
，
建造和营运是为了实现船舶操作员和船东的意愿和要求。
These owner
’
s
requirements denote the essential considerations
which are to form the basis for the
design.
船东的要求表示了这艘船舶设计最本质的理念
为以后的船舶设计打下了基础。
They
may
be
generally
stated
as
船东的要求一般包括
(1)
a
specified
minimum
deadweight
carrying
< br>capacity,
（
1
）一个
明确的最小载重量能力
(2) a specified
measurement tonnage
limit,
一个明确
的测量吨位限制
(3) a selected speed at sea, or a
maximum speed on
trial,
试航速度和最大航速
and (4) maximum draft combined with
other draft
limitations.
由于吃水限制而确定的最大吃水
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.
包括这些基本要求，船东还可能提出对于续航力和
最大每马力小时油耗的要求。
Apart
from
these
requirements,
the
ship
owner
expects
the
designer to provide a thoroughly
efficient ship.
除了这些要求，
船东想要设计
者给出一个完整高
效船舶的最初设计方案。
Such expectations include
这些期望包括
(1) minimum
displacement
on
a
specified
deadweight
carrying
capacity,
对于确定载重量的最小排水量
(2)
maximum
cargo
capacity on a minimum
gross
tonnage,
对于确定总吨位的最大装货能力
(3)
appropriate strength
of
construction,
适当的结构强度
(4)
the
most
efficient
type
of
propelling
machinery
with
due
consideration to weight, initial
condition, and cost of operation,
由船舶重量
和初始条件和营运
成本决定的最适合的主机引擎
(5)
stability
and
general
seaworthiness,
稳性和适航性
and
(6)
the best loading and unloading
facilities and ample accommodations for stowage.
和最佳装货和
卸货设备及足够的舱容。
Design
procedure
设计步骤
From the specified
requirements, an approach is made to the selection
of the dimensions, weight,
and
displacement of the new design.
根据指明的条件
，新设计需要先近似估算决定船舶的尺
寸，重量和排水量。
Th
is is a detailed operation, but some rather direct
approximations can be
made to start the
design process.
这是一个复杂的过程，但是一些简单而直接的近似方
法何以
用来开始设计过程。
This is usually
done by analyzing data available from an existing
ship which
is closely similar.
通常这个过程是从认真分析母型船的资料开始的。
For
example, the design
displacement can be
approximated from the similar
ship
’
s known deadweight of
比如说，设计排
水量可根据型船的载重量近似取值
< br>,
say,
11790
tons
and
the
known
design
displacement
of
17600
tons.
比如说，根据
型船
11790t
的载重量取到
17
600t
的排水量
.
From
these
figures,
a
deadweight-displacement ratio of 0.67
is obtained.
这个近似中，载重量与排水量的比例取的是
< br>0.67. 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.
这即是说，如果新船的设计载重量是
10000t
，那么近似的设计排水量就是
10,000/0.67
或者取
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.
在排水量确定后，在综合考虑速度，稳性和
强度的要求就可以成为初定船长，船宽和吃水的起始点。
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.
船宽是
指船舶横向的最大宽度，吃水是指从船舶水线到纵向最低处的深度。
Length and speed
船长和航速
These
factors are related to the hull form, the
propulsion machinery, and the propeller design.
船
长和航速与船舶外壳形状，
主机和螺旋桨
的设计有关。
The hull form is the direct
concern of the
naval architect, which
the propulsion machinery and propeller design
are
the second concern.
船
舶的型线是造船工程师的主要考虑因素，主机和螺旋桨的设计则位居其
次。
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.
造船工程师对最终船舶
效率，重量，推进器尺寸和船体线性的选择有相当重要的影响和作用。
Speed has an
important influence on the length selected for the
ship.
船速对船长的选择有重
要的影响。
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.
船速于船长的关系可以通过这
个比例表示出来
V/
L
，这里的
V
是以
节为单位的船速，
L
是船舶的水线长。
As
the
speed-
length ratio increases, the resistance of the ship
increases.
如果
V/
L<
/p>
增加，则船舶的阻
力也随之增加。
The
refore, in order to obtain an efficient hull form
from a resistance standpoint, a
suitable length
must be
selected for
minimum resistance.
因此想要从船舶阻力的方面选择合适
的船体型线，
必须
从最小阻力的角度选择船舶的长度。
Length in
relation to the cross-sectional
area of
the underwater form (the prismatic coefficient),
is also very important insofar as resistance
is concerned.
跟阻力因素相同重要的是，船舶
代表性的水下形状（可以用菱形系数表示）对
船长的影响。
Fa
st
ships
require
fine
(slender)
forms
or
relatively
low
fullness
coefficients
as
compared with relatively
slow ships which may be designed with fuller hull
forms.
快速船舶的船
体型线都较为尖瘦，
菱形系数也较小，
而低速船舶的船体型线都较为丰满，
菱形系数也较大。
Beam and stability
船宽和船舶的稳性
A
ship must be stable under all normal conditions of
loading and performance at sea.
船舶在各
种载况和航行条件下必须保持稳性。
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.
当船舶
由于外力偏离垂
直面时，外力撤出后船舶必须有回复的能力。
Stability may be
considered in
the transverse or in the
longitudinal direction.
稳性包括船舶的横向和纵向稳性。
In surface
ship,
longitudinal stability is much
less concern than transverse stability.
对于水面舰艇来说，船舶的
横向稳性比纵向稳性更重要。
Su
bmarines, however, are concerned with longitudinal
stability in
t
he submerged c
ondition.
对于潜水艇来说就，在水下的纵向稳性是主要考虑因素。
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.
船舶的横向
稳性可以分为两种情况
，在倾角较小情况下的初稳性，和倾角较大的大倾角稳性。
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 .
初稳性由两个因素决定
1
在基线上的重心高度
2
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