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26 LAKE SHIP YARD METHODS OF STEEL SHIP CONSTRUCTION. BY ROBERT CURR. THE ADVANTAGES OF MOLD WORK. The greatest advantage derived from the mold system-is the continual work- ing of the machinery in the punch shop TAE MaRINE REVIEW * straight line. The keel plate and liner measure approximately two inches and D strake and liner one and one quarter © inches, so that the height above the keel plate will measure three and. three-quar- ters inches at end of straight line where the curve of bilge commences, shown from the beginning to the launching of the vessel. This cannot be accomplished on a single vessel by the old method of lifting the work from the ship. Where two or three vessels are building at one time the punch shop tools may be kept going continuously, but otherwise on the old system. The despatch of the building of a ves- sel depends entirely on the output of the punch shop and when six men can furnish work for 13 punching machines workirig night and day it goes to show the advantage of the mold system. With the mold system of laying out the material, two -building berths are ample for any large concern, because in a few days after the punch shop work is done the vessel can be launched, pro- viding the machinery space of the vessel has been got ready for the engine and boiler builders to get same installed. In the mold system any part of the vessel can be built first so that there is no trouble in getting the engine and boiler space ready first. The riveting as ex- plained is well cleaned up so that no odd work is left, which is a large item both in economy and despatch. The ribbanding of a vessel is quite an item and is practically dispensed with on the great lakes. The bottom plating is put up along with the keel plating and center keelson as shown by Fig. 179. The bottom of the vessel has a rise of three inches in the width and this is taken care of as shown by Fig. 179. A straight edge is held to the under- side of the keel plate and the difference measured at D strake, the ending of the 172. , by Fig. 179. In this way the bottom is tested as regards the rise of floor. Very little troublé is experienced in fetching the bottom to the proper rise FIG, ' because the bottom framing is all riveted on the ground prior to erecting and when fastened to the center keelson pulls the shell plating in place if it should be near- er a straight line than the rise designed. When the plating is put upon the -bottom the straight edge will be used every hundred feet so that the plating will require less bolting up when the framing: is placed on the plating than "when wholly dependent on the eye. To hold the plating in place shores of scant- ling size are used which .serve the pur- pose until the bulk of the bottom ma- terial is in place. ; The top sides are proceeded with as soon as the margin plate is on. The belt frames are erected and all the length- way parts run'so that the frames are attached to same, the longitudinal parts serving the purpose of ribbands. The deck work follows in the same way and as soon as the arch plates are in the girders under the deck are run and the beams are rested on and bolted to same. The intercostal work is all riveted up, then the shell and_ stringer plating is erected in place without the aid of either shores or ribbands. The -erecting of the material where all the parts can be completed) effects a saving in time and cost and the wood 173.