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June, 1918 faired. Assume the two endmost of the stations so faired to be absolute and invariable; and in fairing the extremities of the ship by the ordinary method, let the batten pass through all the spots in these stations in the same manner as if it were 'the mid- ship section, taking care, however, to iet the batten pass through points obtained from the adjacent stations, so that there may be no discontinuity in the surface of the ship where the portion of the body faired by the con- tracted method joins to that faired by the ordinary method. - One of the chief advantages of the method of fairing which we have just been describing, consists in the facility _ with which the molds of the square body can be sent out, and the timbers converted before the fairing of. the. extremities of the ship is completed. It may be remarked, that when the . square stations are not equidistant, it will be necessary to space the per- pendicular lines, by which the curves are set off, at distances from each other proportional to the spacing of the square stations. There is no necessity for using the level and diagonal lines already in the body, as any lines may be. used for the purpose of fairing. It will be readily seen that not only is the contracted method correct in- principle, but owing to the ordinates of the curve being placed closer to- gether, the curvature is increased, and, therefore, the battens are more likely to spring fairly than when the curves are nearly straight. Projections of Diagonals on the Sheer Plan We will now get in a set of lines, which, although seldom used for the purpose of fairing, yet serve to prove that fairness, when drawing upon paper. The lines referred to are the projections of the diagonal lines on the sheer plane. The chief use of these lines is to give the positions of the heads and heels of the timbers when disposed in the sheer plan, upon boards which are given to the work- men for their guidance in fairing the ship. It has been already remarked, that diagonals are used as harpin lines; of these diagonals there are two sets, viz., heads or harpins, and filling heads or sirmarks. The former give the lines of the heads of frame timbers, and the latter of filling or doubling frames. An arrangement of diagonals in the body plan is shown by Fig. 5; those marked FH, 1H, 2H, etc. being the floor head, first head, second head, etc. harpins, respectively; while those marked FS, "Ast S, 2nd S, etc., are the floor sirmark, first sirmark, second sirmark, etc., Te- spectively. The same names are given to the corresponding diagonals in the half-breadth and sheer plans. At some yards a different nomenclature is adopt- ed; the sirmarks FS, lst S, 2nd S, etc., being known as. S.F.H., F.F.H.,F. 1st H., etc., or short floor head, filling floor head, filling first head, etc., while the same names, as before stated, are given to the heads of the frame timbers. Further particulars regarding the dis- position of the timbers composing the frames and filling frames, are given in the next chapter. To Obtain Ending The diagonals in the sheer plan are generally copied upon paper to a y-inch scale, being laid off from the sheer draft without reference to the floor. When the frames are disposed, the drawing is copied upon a board and given to the workmen for their guidance, as before stated. . Measure j the height, Fig. 12, square from the base line of the body plan, at which a diagonal line ab cuts each square station, 1, 2, 3, etc., and set these distances upon the corresponding square stations in the sheer, measuring from the base line of that plan. A line a,b,, drawn through these points is the diagonal in the sheer plan. Diagonal lines are generally ended at the beard- ing line, and the ending is obtained by measuring the height above the base line of the body plan at which the diagonal cuts the half siding of. stem or stern post and setting this height square from the base line in the sheer to cut the bearding line; the point on the bearding line,. so obtained, is the ending of the diagonal. Up to the present time we have been working with only every second, third, or perhaps fourth square sta- tion drawn in each plan. These were sufficient to fair the body by; and, indeed, were preferable to having the whole of these stations drawn, owing to the greater clearness resulting from fewer lines being drawn upon the floor. The intermediate stations may now be supplied. As these stations ap- pear straight in the sheer and half- breadth, they are first drawn in those: plans by dividing the space between two consecutive square stations, as. at present drawn, into the requisite number of equal parts, and drawing vertical lines through the points thus obtained. They are then easily trans- ferred from these plans into the body plan by the methods already given. If the body is fair, the new square stations will pass through all the points set off for them. Either at this stage of the work, 'er before putting in the intermediate square stations, it is necessary to draw ys THE MARINE REVIEW 257 the 'top side line, - top-breadth line, and other lines which at all conform to the sheer of the ship. These lines -- will appear curved in all the plans. Measure with a scale from the sheer draft the height above the base line of the sheer plan at which the top side, top-breadth, or other such line, cuts each square station and set up these heights on the corresponding square station in the sheer, and pass a batten through as many of the points, so found, as is consistent with fairness.. It will be found, that this line will not differ materially from a line copied upon the floor previous to the body being faired. When the line is copied into the sheer plan, it 'can be transferred to the body plan, by measuring the height above the base line at which it intersects each square. station, and setting up these heights upon the corresponding square stations in the body plan, measuring square from the base line of that plan. A curve passed through the ' points so obtained, will be the projec- -- tion in the body plan of the sheer line referred to. To transfer the line to the half-breadth plan,. measure the 'distance square from the middle line of the 'body plan at which the sheer line cuts each square station, and set these distances upon the correspond- ing square stations in the half-breadth, measuring from the middle line of that plan. A curve passed through these points will be the horizontal - projection of the sheer Aine. The sheer lines are ended at the bearding line similarly to the horizontal ribband lines. Locating the Screw Shaft When the after body of a screw ship has been faired, the height and direction of the center of screw shaft are drawn in the body and_ sheer plans. A circle is then swept in the former plan, the center of which is the center of shaft, and the radius is that of the shaft plus the scantling of timber which is allowed around. it. It should be remarked that the scantling taken for the radius does not usually include the boxen wood allowed in lieu of the bottom plank- ing. The after square stations are then bent, so that all which would otherwise intersect with this circle are made tangents to it. The bent portions are then, faired by putting additional level lines/it the vicinity of the swell, transferring them to the half-breadth plan, and. recopying the stations as, before described. After this is done, & ls: of the outside of the plank drawn parallel to these, and the molds to the stern 'post, ete., are made to the outer lines, thus allowing for the boxen. Fig. 11