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 hay ve bee 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 urface 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 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 extentcomputer. 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