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6 MARINE REVIEW. Laying Down. Almost every person who has never seen a vessel before remarks, what a graceful or handsome vessel, etc.; few there are however, who understand how the eveness or fairness is obtained. It is the intention to here give a few outlines of the opera- tion of how this evenness or fairness is produced. Although many of the details will have to remain unexplained in this paper at this time, 'laying down," as it is called in ship-build- ing, consists of drawing on a floor the lines or shape of the vessel to the full size. In order to do this, the vessel is represented as being cut in sections, usually three ways: First, crossways, Fig. A; sec- ond, on level or parallel lines with the water line, Fig. B; and third by vertical section or parallel lines with that through the keel, stem or stern post, Fig. C. These sections are, as shown, first, the body plan, which forms the most prominent part and represents the vessel as being cut crossways of the keel. Second, the breadth plan, which represents the vessel as being cut by parallel lines with the water line. Third, the sheer plan ora longitudinal view, supposing a vessel to be divided or cut right through centre, and looking at one of the halves where divided. These three plans combined are what is generally known as the draught of aship. Without due attention and accuracy in lay- ing down, it is almost impossible to obtain a good form of vessel and insure fairness; nor could the architect without them give any statement of the probabilities of the behavior or speed, or estimate accurately the weight of the structure, carrying capacity or cost. compiling the table, as well as in the setting off in ee Saal aoe table 5 usually made to read feet, inches and eighths of an inch. It measurement isa trifle more than % the sign + is added and it less the sign -- is added; thus 12, 3, 7-|- would be 12 feet, 3 inches and 7%, full. Now strike or mark on the floor a straight line DD, as shown on body plan. This is called the base line. . Next erect a line at right angles to base FF on body plan. This line will be the centre line of vessel. Make parallel lines with base line DD, 2, 4 and 6 feet apart. These are termed water lines. Now set off parallel lines on each side of centre line. They are usually dotted on the body plan. Also put a line each side of centre for breadth of ship and then set off FG, which represents rise of floor. Next we strike a level line EE, which will represent centre of ship, and run parallel lines at 2 feet, 4 feet and 6 feet apart. Of course we assume in this case only 3 sections, lines 2 feet apart, but number and spacing may be lessened or increased to suit size of vessel. At base line on plan B set off frame sections Onl 204, 5) 6) yoy ab lei aneles fo base line. They generally represent every sixth frame, but can be varied according to shape of ship. 'The 0 and 8 in this case are called the after and forward perpendiculars. In plan C, sheer plan, we mark off DD, and draw lines parallel to base 2, 4 and 6 feet asunder; they are termed water lines same as on plan A, body plan. Next set off fame sections on vertical lines 0, I, 2, 3, 4, 5, 6, 7, 8, at right angles to base; space and number similar to those on half breadth plan. When this is finished, all the fixed lines are established on floor. It is customary in laying off the sheer and half breadth SWEER PLAN, : C. s f 71 5 Sao ASHEER LINE. r e °. . q : e e e . : oe e . Se bs x g ae . .. 8 e ¢ e ary NS oe ie: § e aS ~ o e ' 63 Sen ~ eee Ag a : aa es IS 2 : : " cae . - mac pits a * a Ay = ~ 2 e oe weeny ne L i 2S - « a Sats oe : a Se ee sete a eee 2 Cie See aie - Sigs seis times ie ee acer as oan ene tere! ehekie secon: ® ? ' 2 é 4 < : St: v 8 Bon HALF- BAREAOTH PLAN, ao eeses cee 9e © ORO4 CC es oe OH NM OV OS C0884 SOe Oy BDOSEIEs DEES oSSe 'enceR Unc. > To commence to lay a vessel down, the first thing necessary is a level (or nearly so) floor. It need not be so long that the whole length of the vessel may be represented at full length, but must be wide enough to take the full width and depth of the vessel. Some of the government navy yards have lofts of sufficient size for the full lengths of the largest vessels, but in general use this is not the case. Next, a measuring batten or pole is to be made, and this pole is to be the standard for all measurements both in this work and in the building yard. It is very important to establish this at the very outset. Now make a long batten or pole about 2% inches by 34 inch thick, that will extend the entire length ot the floor, to be used for sheer line, or those not requiring much curve, and known as the sheer batten. Also one about 14 inches by % inch thick, suitable for being used on greater curves and known as the water line batten. Also one about 34 inch by % inch thick and known as the body plan batten. . It will be found convenient to have at hand several smaller battens, with the sizes reduced and the ends tapered for use on special curves. A number of large awls should now be made for holding the battens in place; some loft men, however, prefer nails sharpened to a point for this use; also have chalk of two or more colors, and wide pencils. . raving decided on a satisfactory plan or model, to transfer the same to the floor, you will begin, first taking the measure- ments from the plan or model by a scale in the same manner as they are to be placed on the floor. In doing so it is customary to make a "table of ordinates."" Much labor will be saved in the loft room by using great care and accuracy in reading BOD Y PLAN A, plans, to make base line DD serve as the base line EE for the half breadth plan (or in other words, having sheer plan C and hair breadth plan D made asone plan). By this means halfthe floor space only is required. Where mould loft is rather short to admit of vessel being laid down full length, the vessel may be contracted, that is, frame sections are placed half the proper distance asunder. In vessels with very fine lines it is advisable to contract the length, especially at the ends, as it causes the lines to show more of a fullness or curve, and consequently the battens will give a quicker curve, and detect errors in setting off any uneven places in the lines. From "table of ordinates" mark sheer spots at all the section lines on sheer plan C, and with long batten draw the sheer line fore and aft, using a piece of chalk. From "'table of ordinates" mark points for stem at each water line, and measuring forward from frame section 7, place a batten on the points obtained and draw in curve for shape of stem; also from table mark off stern points at certain level lines parallel with water line and draw in curve by the aid'of a batten. From the table, set off on body plan A half breadth at 2 feet water line, also half breadth at 4 feet and 6 feet water line, and half breadth and heighth of rail for mid- ships frame section 4. Nail or pin a batten down to the points already obtained and see that the curve is fair, and then draw it with a chalk or pencil. Next take frame section 5, mark half breadths at the various water lines and rail, and draw through points with batten as before. Proceed and line in all the other frame sections on body plan in similar way as 4. If batten does not pass exactly through spots do not force it back to spots, but see that the curve is fair: height of foot of 7 section line to be taken from 7 section line