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Isherwood System of Construction Showing Very Graphically the Amount of Work That Can be Put Together in a Great Lakes Shipyard* A. plan accompanying this ar- ticle shows the amount of work put together in a great lakes ship yard in a few hours, As is shown by plans the bottom plating to E strake is erected with all the interior work. Assuming that the foundation of the building berth is sound, the keel blocks have to be laid to a suitable height so that the rivets in the bot- tom can be driven. The keel blocks are simply cuttings from pine logs 16 in. to 12 in. square. The cuttings are built up to a height- of 4 ft., the bottom piece being about 5 ft. long and the top 12 'in. The top of the blocks are perfectly level and a straight line scored in on the middle of the completed blocks. *This is the thirteenth of a series of ar- ticles on the Isherwood system of construction 'which began in the September, 1912, issue of THe Marine Review. The first article dealt 'with the general specifications of the steamer, the second with the sheer, half-breadth and body plans; the third explained the method of getting the sheer; the fourth dealt with the longitudinal and transverse framing; the fifth with offsets; the sixth with the shell -plating/"-the seventh with the shell plating 'expansion; the. eighth with the arrangement of plates and angles forming the spar deck; the ninth with the 'transverses; the tenth with bulk head construction; the eleventh with the connection of longitudinal frames to the bulkheads and transverses; the twelfth 'showed .the interior framing between the tank The blocks are spaced 5 ft. apart and braced in a way that with ordin- ary care will not be pushed out of place in landing the keel plates on them. Center lines are punched or nicked in on the keel plates and are a guide in keeping the keel plates straight when erecting. This line as a rule is on both sides of the plate before erecting so that the line on the under- side will be laid on the line on the keel blocks. If the butts of the keel plates are planed square there is no trouble in getting the keel perfectly straight. After the keel plates are erected the next strake B is put up, which makes good footing for the men in erecting the center keelson. By the time the center keelson is erected and riveted the bottom plat- ing is in place as seen by plans. The longitudinal frames follow up 'with the strakes of plating they are on, Lhe bottom plating has-a rise. of 3 im: in the -half.width and this "is tested by applying a straight edge under the bottom, the plating being shored up to that height above the level board. When the plating is shored up to its proper place the transverses and By Robert Curr 'place which are the means of fair- ing up the bottom. The bottom plating being four transverse spaces long it gives a splendid opportunity for the shift of butts of all the plating forming longitudinal members. The 10 ft. shift of butts here is not necessary for half that distance will show that the shearing of the rivets in the plat- ing is even greater than the plating between the frames. The keel plate, center keelson and rider plate form a girder and are con- sidered the backbone or at least a structural part of special importance. The center keelson and the rider plate are shown above the body plan and as the butts are clear of each oth@r about 10 ft. there is no need of dwelling on that point at this time. The center keelson like the keel plate is continuous from the stem to the stern post and the rider plate is continuous all the length of the tank from bulkhead No. 2 to after end of tank No. 29. The keel plate should be as wide as to have at least two rivets be- tween the edge of the next strake and the toe of the keel angle. Considering the water tight floor angle to the shell as a point in view top and spar deck. ; watertight floors are dropped into the section thro' No. 12 shows this ' ' Tana ENO. ars a Lee oe a To eo i | Beare ae See SS tS Se St SS = SS , L eer fi be itt tl i i i ut SA 29 24 a "a7 DETER | PELE ier. ie 23 22 2/ = 2 a é 3 ti a. LIT ice td -- 4 FPA eden freee ge 28 Bae PLAN SHOWING THE AMOUNT OF WORK THAT CA N BE