Lesson Six
Ship Lines
The outside surface of a ship is the surface of a solid with curvature in two directions,The curves which express this surface are not in general given by mathematical expressions,although attempts have been made from time to time to express the surface mathematically,It is necessary to have some drawing which will depict in as detailed a manner as possible the outside surface of the ship,The plan which defines the ship form is known as a ‘line plan’,The lines plan consists of three drawings which show three sets of sections through the form obtained by the intersection of three sets of mutually orthogonal planes with the outside surface.
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 in this way are called ‘body section’ and are drawn in what is called the ‘body sections’ as shown in Figure 1*,When drawing the body plan half-sections aft of amidships（the after body sections）are drawn on one side of the centre line and the sections forward of amidships (the fore body sections) are drawn on the other side of the center line,It is normal to divide the length between perpendiculars into a number of divisions of equal length (often ten) and to draw a section at each of these divisions,Additional sections are sometimes drawn near the ends where the changes in the form become more rapid,In merchant ship practice the sections are numbered from the after perpendicular to the forward perpendicular —thus a.p,is 0 and f.p,is 10 if there are ten divisions,The two divisions of length at the ends of the ship would usually be subdivided so that there would be sections numbered 1/2,11/2,81/2,and 91/2,Sometimes as many as 20 divisions of length are used,with possibly the two divisions at each end subdivided,but usually ten divisions are enough to portray the form with sufficient accuracy.
Suppose now that a series of planes parallel to the base and at different distances above it are considered,The sections obtained by the intersections of these planes with the surface of the ship are called ‘waterlines’ or sometimes ‘level lines’,The lines are shown in Figure 1,The waterlines like the body sections are drawn for one side of the ship only,They are usually spaced about,1m (3-4ft) apart,but a closer spacing is adopted near the bottom of the ship where the form is changing rapidly,Also included on the half breadth plan is the outline of the uppermost deck of the ship.
A third set of sections can be obtained by considering the inter-section 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’ see Figure 1 and are called ‘buttocks’ in the after body and ‘bow lines’ in the fore body or often simply ‘buttocks’,The buttocks like the waterlines will be spaced 1m (3-4ft) apart,On the sheer profile the outline of the ship on the centre line is shown and this can be regarded as a buttock at zero distance from the centre line.
The three sets of sections discussed above are obviously not independent of one another,in the sense that an alteration in one will affect the other two,Thus,if the shape of a body section is altered this will affect the shape of both the waterlines and the buttocks,It is essential when designing the form of the ship that the three sets of curves should be ‘fair’ and their interdependence becomes important in this fairing process,What constitutes a fair curve is open to question,But formerly the fairing process was done very largely by eye,Nowadays the lines plan is often faired by some mathematical means which will almost certainly involve the use of the computer,However the fairing process is carried out the design of the lines of a ship will normally start by the development of an approximate body plan,The designer when he has such a body plan will then lift offsets for the waterlines and will run the waterlines in the half-breadth plan,This means drawing the best possible curves through the offsets which have been lifted from the sections,and this is done by means of wooden or plastics battens,If it is not possible to run the waterlines through all the points lifted from the body plan then new offsets are lifted from the waterlines and new body sections drawn,The process is then repeated until good agreement is obtained between waterlines and body sections,It is then possible to run the buttocks,and to ensure that these are fair curves it may be necessary to adjust the shape of body sections and waterlines.
The process of fairing is usually done in the drawing office on a scale drawing,It is clear that a much more accurate fairing of the form is necessary for production purposes in particular,and this used to be done in the mould loft of the shipyard full size,The procedure was for the drawing office to send to the mould loft office from the lines as faired in the office and they were laid out full size on the loft floor,A contracted scale was adopted for the length dimension but waterline and section breadths and buttock heights were marked out full size,The same process of fairing was then adopted as used in the office,the fairing being done by using wood battens of about 25mm square section pinned to the loft floor by steel pins,To save space the waterlines and buttocks in the forward and after bodies were overlapped in the forward and after bodies were overlapped in the length direction,This type of full scale fairing enabled sections,waterlines and buttocks to be produced which represented the desired form with considerable accuracy,From the full scale fairing,offsets were lifted which were returned to the drawing office and made the basis of all subsequent calculations for the ship,as will be seen later.
A more recent development has been the introduction of 1/10 scale lofting,which can be done in the drawing office,and the tendency has been to dispense with full scale loft work,Several methods have also been developed for the mathematical fairing of ship forms and linking this up with production processes,Discussion of these topics,however,is outside the scope of this work..
The lines drawn on the lines plan representing the ship form are what are called,moulded lines”,which may be taken to represent the inside of the plating of the structure,The outside surface of the ship extends beyond the moulded lines by one thickness of shell plating in an all welded ship,When riveting was put on in a series of,in” and,out” strakes,In this case the outsides surface of the ship extended two thicknesses of plating beyond the moulded lines in way of an outside strake and one thickness beyond the moulded lines in way of an inside strake,Actually the outside surface would be rather more than one thickness or two thicknesses of plating,as the case may be beyond the moulded line in places where there is considerable curvature of the structure,as for example at the ends of the ship or below the level of the bilge.
In multiple screw merchant ships it is customary to enclose the wing shafts in what is called a,shaft bossing”,This consists of plating,stiffened by frames and extending from the point where the shafts emerge from the ship and ending in a casting called a,shaft bracket”,The bossing is usually faired separately and added on to the main hull form,The bossing is treated as an appendage.
In many ships of the cross section does not change for an appreciable distance on either side of amidships,This portion is called the,parallel middle body” and may be of considerable extent in full slow ships but may not exist at all in fine fast ships,Forward of the parallel middle the form gradually reduces in section towards the bow and in like manner the form reduces in section abaft the after end of the parallel middle,These parts of the form are called respectively the,entrance” and the,run” and the points where they join up with the parallel middle are referred to as the,forward” and,after shoulders”.
(From,Naval Architecture for Marine Engineering” by W,Muckle,1975)
Technical terms
ship lines 船体线型
ship form 船体形状
mathematical expressions 数学表达式
drawing 图，拉延
lines plan 型线图
orthogonal plan 正交平面
body section 横剖面
body plan 横剖线图
symmetry 对称
water lines /level lines 水线，水平型线
half breadth plan 半宽水线图
view 视图，观察
sheer profile 侧视图，纵剖线图
buttocks 后体纵剖线
bow line 前体纵剖线
after/fore body 后/前体
alteration 修改，变更
fairing process 光顺过程
offsets 型值
to lift offsets 量取型值
20．Wooden/plastics battern 木质/塑料压条
21,drawing office 制图/设计室
22,mould loft 放样间
23,full size 实尺（1：1）
24,loft floor 放样台
25,contracted scale 缩尺
26,lofting 放样
27,steel pin 铁钉
28,mathematical fairing of ship form 船体数学光顺法
29,screw 螺旋桨，螺钉
30,wing shaft 侧轴
31,shaft bossing 轴包套
32,casting 铸件
33,shaft bracket 轴支架
34,appendage 附属体
35,parallel middle body 平行中体
36,full slow ship 丰满的低速船
37,fine fast ship 尖瘦的快速船
38,entrance 进流端入口
39,run 去流端，运行，流向
40,forward/after shoulder 前/后肩
Additional Terms and Expressions
grid 格子线
ordinate station 站
midstation 中站
station ordinate 站线
finished/returned offsets 完工型值
table of offsets 型值表
diagonal 斜剖线
keel line 龙骨线
rake of keel,designed drag 龙骨设计斜度
knuckle line 折角线
preliminary offsets 原始型值
mathematical lines 数学型线
mathematical fairing of lines 型线数学光顺法
Notes to the Text
in as detailed a manner as possible 相当于 in a manner as detailed as possible,阅读和翻译科技原文时，应注意这类不一般的语序。
关系词what可引出主语从句，表语从句等。例如：…in what is called the ‘body plan’及…in what is called a ‘shaft bossing’中的what从句作为介词in的宾语从句。
What constitutes a fair curve is open to question…中的what从句为主语从句。
The lines drawn on… are what are called moulded lines 中的what 从句为表语从句。
When drawing the body plan half-sections only are shown because of the symmetry of the ship.
When drawing the body plan 是省略了主语和谓语一部分（to be）的时间装语从句，尽管从句和主句的主语并不一致。这种省略方法似乎与一般的英语语法规律有矛盾，但在科技文献中较常见，其原因是这类省略不会引起读音的误解。
a.p.和f.p.分别为after perpendicular (尾垂线)和forward perpendicular (首垂线)的缩写。
Also included on the half-breadth plan is the outlines of the uppermost deck of the ship.
这是依据倒装句，为了突出情调部分，此句中的also included on the half breadth plan 这部分移至句首，主语the outline of…反而置于句末。
on a scale of 1/4 in to 1 ft or on 1/50 scale 以一个1/4英寸代表1英尺的比例尺（即1：48）或1:50的比例尺。
The procedure was for the drawing office to the mould loft offsets from the lines as faired in the office and they were laid out full size on the loft floor.
for the drawing office to send….是”for+名词+不定式”结构，在句中作表语。For后面的the drawing office 可看作不定式的逻辑主语。
Offsets 是不定式to send 的宾语。由于它后面有一个较长的介词短语from the line (其后面又有as faired in …,On the loft floor 修饰the line )加以修饰，为了句子结构平衡的需要，被移至介语短语to the mould loft (作为地点状语用)之后。
in way of….在…部位，在….处这一组合介词在造船和海洋工程英语中用得较普遍。例：The structural strength of a ship in way of the engine and boiler space demands special attention the designer.
机炉舱部位的船体轻度要求设计人员给予特别的注意。
The thickness of upper shell plating should be increased in way of the break.
船楼端部处的上层壳板厚度应该增加。/
9.as the case may be 按情况而定。
Ship Lines
The outside surface of a ship is the surface of a solid with curvature in two directions,The curves which express this surface are not in general given by mathematical expressions,although attempts have been made from time to time to express the surface mathematically,It is necessary to have some drawing which will depict in as detailed a manner as possible the outside surface of the ship,The plan which defines the ship form is known as a ‘line plan’,The lines plan consists of three drawings which show three sets of sections through the form obtained by the intersection of three sets of mutually orthogonal planes with the outside surface.
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 in this way are called ‘body section’ and are drawn in what is called the ‘body sections’ as shown in Figure 1*,When drawing the body plan half-sections aft of amidships（the after body sections）are drawn on one side of the centre line and the sections forward of amidships (the fore body sections) are drawn on the other side of the center line,It is normal to divide the length between perpendiculars into a number of divisions of equal length (often ten) and to draw a section at each of these divisions,Additional sections are sometimes drawn near the ends where the changes in the form become more rapid,In merchant ship practice the sections are numbered from the after perpendicular to the forward perpendicular —thus a.p,is 0 and f.p,is 10 if there are ten divisions,The two divisions of length at the ends of the ship would usually be subdivided so that there would be sections numbered 1/2,11/2,81/2,and 91/2,Sometimes as many as 20 divisions of length are used,with possibly the two divisions at each end subdivided,but usually ten divisions are enough to portray the form with sufficient accuracy.
Suppose now that a series of planes parallel to the base and at different distances above it are considered,The sections obtained by the intersections of these planes with the surface of the ship are called ‘waterlines’ or sometimes ‘level lines’,The lines are shown in Figure 1,The waterlines like the body sections are drawn for one side of the ship only,They are usually spaced about,1m (3-4ft) apart,but a closer spacing is adopted near the bottom of the ship where the form is changing rapidly,Also included on the half breadth plan is the outline of the uppermost deck of the ship.
A third set of sections can be obtained by considering the inter-section 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’ see Figure 1 and are called ‘buttocks’ in the after body and ‘bow lines’ in the fore body or often simply ‘buttocks’,The buttocks like the waterlines will be spaced 1m (3-4ft) apart,On the sheer profile the outline of the ship on the centre line is shown and this can be regarded as a buttock at zero distance from the centre line.
The three sets of sections discussed above are obviously not independent of one another,in the sense that an alteration in one will affect the other two,Thus,if the shape of a body section is altered this will affect the shape of both the waterlines and the buttocks,It is essential when designing the form of the ship that the three sets of curves should be ‘fair’ and their interdependence becomes important in this fairing process,What constitutes a fair curve is open to question,But formerly the fairing process was done very largely by eye,Nowadays the lines plan is often faired by some mathematical means which will almost certainly involve the use of the computer,However the fairing process is carried out the design of the lines of a ship will normally start by the development of an approximate body plan,The designer when he has such a body plan will then lift offsets for the waterlines and will run the waterlines in the half-breadth plan,This means drawing the best possible curves through the offsets which have been lifted from the sections,and this is done by means of wooden or plastics battens,If it is not possible to run the waterlines through all the points lifted from the body plan then new offsets are lifted from the waterlines and new body sections drawn,The process is then repeated until good agreement is obtained between waterlines and body sections,It is then possible to run the buttocks,and to ensure that these are fair curves it may be necessary to adjust the shape of body sections and waterlines.
The process of fairing is usually done in the drawing office on a scale drawing,It is clear that a much more accurate fairing of the form is necessary for production purposes in particular,and this used to be done in the mould loft of the shipyard full size,The procedure was for the drawing office to send to the mould loft office from the lines as faired in the office and they were laid out full size on the loft floor,A contracted scale was adopted for the length dimension but waterline and section breadths and buttock heights were marked out full size,The same process of fairing was then adopted as used in the office,the fairing being done by using wood battens of about 25mm square section pinned to the loft floor by steel pins,To save space the waterlines and buttocks in the forward and after bodies were overlapped in the forward and after bodies were overlapped in the length direction,This type of full scale fairing enabled sections,waterlines and buttocks to be produced which represented the desired form with considerable accuracy,From the full scale fairing,offsets were lifted which were returned to the drawing office and made the basis of all subsequent calculations for the ship,as will be seen later.
A more recent development has been the introduction of 1/10 scale lofting,which can be done in the drawing office,and the tendency has been to dispense with full scale loft work,Several methods have also been developed for the mathematical fairing of ship forms and linking this up with production processes,Discussion of these topics,however,is outside the scope of this work..
The lines drawn on the lines plan representing the ship form are what are called,moulded lines”,which may be taken to represent the inside of the plating of the structure,The outside surface of the ship extends beyond the moulded lines by one thickness of shell plating in an all welded ship,When riveting was put on in a series of,in” and,out” strakes,In this case the outsides surface of the ship extended two thicknesses of plating beyond the moulded lines in way of an outside strake and one thickness beyond the moulded lines in way of an inside strake,Actually the outside surface would be rather more than one thickness or two thicknesses of plating,as the case may be beyond the moulded line in places where there is considerable curvature of the structure,as for example at the ends of the ship or below the level of the bilge.
In multiple screw merchant ships it is customary to enclose the wing shafts in what is called a,shaft bossing”,This consists of plating,stiffened by frames and extending from the point where the shafts emerge from the ship and ending in a casting called a,shaft bracket”,The bossing is usually faired separately and added on to the main hull form,The bossing is treated as an appendage.
In many ships of the cross section does not change for an appreciable distance on either side of amidships,This portion is called the,parallel middle body” and may be of considerable extent in full slow ships but may not exist at all in fine fast ships,Forward of the parallel middle the form gradually reduces in section towards the bow and in like manner the form reduces in section abaft the after end of the parallel middle,These parts of the form are called respectively the,entrance” and the,run” and the points where they join up with the parallel middle are referred to as the,forward” and,after shoulders”.
(From,Naval Architecture for Marine Engineering” by W,Muckle,1975)
Technical terms
ship lines 船体线型
ship form 船体形状
mathematical expressions 数学表达式
drawing 图，拉延
lines plan 型线图
orthogonal plan 正交平面
body section 横剖面
body plan 横剖线图
symmetry 对称
water lines /level lines 水线，水平型线
half breadth plan 半宽水线图
view 视图，观察
sheer profile 侧视图，纵剖线图
buttocks 后体纵剖线
bow line 前体纵剖线
after/fore body 后/前体
alteration 修改，变更
fairing process 光顺过程
offsets 型值
to lift offsets 量取型值
20．Wooden/plastics battern 木质/塑料压条
21,drawing office 制图/设计室
22,mould loft 放样间
23,full size 实尺（1：1）
24,loft floor 放样台
25,contracted scale 缩尺
26,lofting 放样
27,steel pin 铁钉
28,mathematical fairing of ship form 船体数学光顺法
29,screw 螺旋桨，螺钉
30,wing shaft 侧轴
31,shaft bossing 轴包套
32,casting 铸件
33,shaft bracket 轴支架
34,appendage 附属体
35,parallel middle body 平行中体
36,full slow ship 丰满的低速船
37,fine fast ship 尖瘦的快速船
38,entrance 进流端入口
39,run 去流端，运行，流向
40,forward/after shoulder 前/后肩
Additional Terms and Expressions
grid 格子线
ordinate station 站
midstation 中站
station ordinate 站线
finished/returned offsets 完工型值
table of offsets 型值表
diagonal 斜剖线
keel line 龙骨线
rake of keel,designed drag 龙骨设计斜度
knuckle line 折角线
preliminary offsets 原始型值
mathematical lines 数学型线
mathematical fairing of lines 型线数学光顺法
Notes to the Text
in as detailed a manner as possible 相当于 in a manner as detailed as possible,阅读和翻译科技原文时，应注意这类不一般的语序。
关系词what可引出主语从句，表语从句等。例如：…in what is called the ‘body plan’及…in what is called a ‘shaft bossing’中的what从句作为介词in的宾语从句。
What constitutes a fair curve is open to question…中的what从句为主语从句。
The lines drawn on… are what are called moulded lines 中的what 从句为表语从句。
When drawing the body plan half-sections only are shown because of the symmetry of the ship.
When drawing the body plan 是省略了主语和谓语一部分（to be）的时间装语从句，尽管从句和主句的主语并不一致。这种省略方法似乎与一般的英语语法规律有矛盾，但在科技文献中较常见，其原因是这类省略不会引起读音的误解。
a.p.和f.p.分别为after perpendicular (尾垂线)和forward perpendicular (首垂线)的缩写。
Also included on the half-breadth plan is the outlines of the uppermost deck of the ship.
这是依据倒装句，为了突出情调部分，此句中的also included on the half breadth plan 这部分移至句首，主语the outline of…反而置于句末。
on a scale of 1/4 in to 1 ft or on 1/50 scale 以一个1/4英寸代表1英尺的比例尺（即1：48）或1:50的比例尺。
The procedure was for the drawing office to the mould loft offsets from the lines as faired in the office and they were laid out full size on the loft floor.
for the drawing office to send….是”for+名词+不定式”结构，在句中作表语。For后面的the drawing office 可看作不定式的逻辑主语。
Offsets 是不定式to send 的宾语。由于它后面有一个较长的介词短语from the line (其后面又有as faired in …,On the loft floor 修饰the line )加以修饰，为了句子结构平衡的需要，被移至介语短语to the mould loft (作为地点状语用)之后。
in way of….在…部位，在….处这一组合介词在造船和海洋工程英语中用得较普遍。例：The structural strength of a ship in way of the engine and boiler space demands special attention the designer.
机炉舱部位的船体轻度要求设计人员给予特别的注意。
The thickness of upper shell plating should be increased in way of the break.
船楼端部处的上层壳板厚度应该增加。/
9.as the case may be 按情况而定。
