Page:The New International Encyclopædia 1st ed. v. 18.djvu/130

* SHIPBUILDING. 100 SHIPBUILDING. are built to carry cargo. The depth is kept as moderate as possible ou account of the shallow- ness of many harbors; and with a given dejjth only a certain breadth is practicable or the righting moment will be unduly great. There- fore it is desirable to increase the displacement vhich pins may be placed. The mold of the frame is laid on the bending slab, and pins in- serted along its edge. The hot iron angle bar (or channel or Z bar), which is to form the frame (or the outer part of the frame, if it is built up of plates and angles), is then pressed 111 II I A X A Fig. 6. sbeeh plan. JiL.. 123 HALF-BREADTH PLAN. Ill II 1 1 II III il % Fig. S BODY PLAN. only by increasing the length ; this means that, after allowing a suitable entrance and run, the re- mainder of the length is applied to extending the parallel middle body. The designs of the naval architect are pre- pared on paper, and are occasionally supple- mented by a wooden model. The three principal plans are the sheer plan (showing sections of the ship made by vertical longitudinal planes), the half-breadth plan (showing sections made by Ivorizontal longitudinal planes), and the body plan (showing sections made by vertical trans- vei«e planes). In the figures the dotted lines 1, 2, 3, are water lines and are the intersections of horizontal longitudinal planes, and the inner sur- face of the planking or plating of the hull ; lines I, II, and in are bow (forward) and buttock (aft) lines, made by vertical longitudinal planes; the full lines in the body plan are sections A, B, C, etc., and A', B', C, etc., made by vertical trans- verse planes, which are passed at equal distances from each other, X being at the point of greatest breadth and called the midship section. In the body plan the right half shows half-sections forward of the midship section and the loft half the half-sections abaft it. In actual plans many more water lines, bow and buttock lines, etc., are shown, for the full plans are of large size. The planking or plat- ing, positions of frames, decks, and much other detail are also shown. The three principal plans are only a small part of the drawings furnished by the architect to the builder. There must be plans for decks, holds, bulkheads, etc.; of ventilating, drainage, lighting, and flushing sys- tems; of engines, boilers, etc.'; and a vast num- ber of plans showing details of construction of parts and fittings. The drawings being completed, the work is taken up by the constructive force. The plans are laid off on the mold loft floor in full size. Wooden molds are then prepared for the frames or else the shapes of the frames are cut (or .scrived) into a great piece of flooring called the scrive board. The frames are heated and bent on the bending slab. This is a large floor of thick metal with a great number of holes in Skid Beams up against these pins and so given its proper cvirvature. A suflicient number of frames hav- ing been prepared, the work of erection begins. Moulding— "l^^ Hammock Berthings Sheer Moulding Sheerl Strakef--: iilge Keel^ Main Frafne ,---sirakeOutsidePlatin|f LlmbepNol'e /' Ungitudinal GarboardStrake-"' Flat Keel Fig. 9. midship section op battleship. The building w.ay is prepared by setting up the keel blocks. These are short heavy timbers a foot or more square built up in piles two or three feet apart and having tlie upper surface shaped to the keel line of the vessel. On these the keel is laid. In nearly all modern steamers