SHIPBUILDING 



409 



uniform lengths of plates. The surface of the 

 model is also marked with lines representing the 

 decks, the transverse bulkheads, the side-ports, 

 &c. From the model as thus prepared, and 

 from various plans, such as deck, bulkhead, keel- 

 son, and floor plans, the draughtsman measures 

 and orders from the makers the angle-bars, bulb- 

 bars, plates, and butt straps. Meanwhile the 

 vessel's lines, as delineated on paper, have been 

 'laid off' on the mould-loft floor full size, in 

 which process inaccuracies due to the small-scale 

 drawing are eliminated. From the mould-loft 

 lines, when accurately ' faired,' moulds and tem- 

 plates of the several parts of the ship structure 

 are prepared for the guidance of the workmen 

 in the shipyard. The most important item thus 

 prepared is the ' scrieve-board,' an immense piece 

 of flooring on which the ' body-plan ' or frame 

 curves and other features are delineated full size 

 by sharp lines cut or 'scrieved' in the smooth 

 surface. This flooring is placed convenient to the 

 angle-bar furnace and the contiguous ' bending- 

 blocks,' massive iron slabs which form the solid 

 flooring on which the frames, &c. are bent. On 

 this floor the form of the frame is marked from the 

 scrieve-boards. All over the floor are round holes, 

 closely spaced and equidistant, into which or 

 those of them which tall within the line of the 

 frame curvature upright pins are placed with their 

 upper ends projecting. Long angle-bars (a, fig. 6) 

 of iron or steel properly heated are now drawn from 

 the furnaces, and speedily bent round the pins to 

 the form required, by special hand appliances. Each 

 separate half-frame of a ship is thus fashioned to 

 the proper curve in little more time than it takes 

 to describe the process. I. is now allowed to cool, 

 and it is then returned to the scrieve-board to be 

 Bet or adjusted with ' reverse frame,' which with 

 the ' floor ' plates go to make the ship's frame in 

 its complete form. The three items tentatively 

 bolted together are now taken to the building- 

 berth, and there riveted together by hand or by 

 hydraulic power machines, the holes for the rivets 

 having been punched by the punching-machine 

 partly before and partly after bending. While 

 tlii* has been going on, trie keel has been laid on 

 the blocks heavy masses of wood, usually 4 to 6 

 feet apart and 3 to 4 feet high, 

 , their tops lying in a plane 

 inclined to the horizon about 

 g inch per foot. The frames 

 as completed are hoisted up 

 in their places, and kept in 

 position 1 1 v shores and ribbon- 

 pieces. The stem and stern- 

 posts are set up, and soon the 

 work becomesgeneral all over 

 Fig. 6. the vessel. The deck-beams 



usually of the forms shown 



in 6 and c, fig. 6 are put up, the bulkheads, 

 stringer-plates, and keelsons are added in due Hue- 

 cession, and the outside shell-plates are curved, 

 punched, fitted, and temporarily fastened with 

 boltfl and nuts ready for the busy hammers of the 

 riveters. 



In vessels built on the cellular double-bottom 

 principle the order of procedure is different from 

 the above, especially in the earlier stages. The 

 frames in this case are in three and sometimes 

 four sectional parts. One part (when three 

 parts are employed) forms the bottom of the 

 vessel, and extends across and through the centre 

 longitudinal (B, fig. 5), terminating against wing- 

 plate D at each bilge. When four parts are used, 

 one begins on each side the centre longitudinal 

 It, to which it is securely attached, and ends 

 against the wing-plate D on each bilge. The 

 remaining two parts form both sides of the vessel, 



T T 



and are superimposed upon the wing-plate, and 

 firmly bracketed to it. In construction there- 

 fore the centre longitudinal and keel are first 

 erected, the bottom sections of the frame fixed in 

 place, and the whole system of longitudinal and 

 deep-floor plates completed before the side port inns 

 of the frames are erected. In other respects the 

 procedure does not materially differ from that 

 above outlined. 



All the iron work entering into the structure is 

 fastened together by rivets. Holes are first punched 

 or drilled in the plates and angle-irons, in most 

 cases before they are put to- 

 gether. The holes having been 

 made exactly to fit over each 

 other, a red-hot rivet is received 

 from the boy rivet-heater, and 

 inserted through them, as in 

 6, fig. 7. A workman called 

 the In ili 1 IT- up' holds the head 

 of the rivet forcibly in place 

 with a heavy iron tool, while Fig. 7. 



two riveters on the other side of 

 the plate strike its point rapidly with their hammers 

 until hammered down flusli with the plating or as 

 shown at a. The contraction of the rivet in cooling 

 causes it to draw, and hold the two plates stifl 

 more tightly together. 



Steamships are divided throughout their length 

 into compartments by transverse bulkheads. These 

 partitions, like the outside shell of the vessel, are 

 made water-tight by 'caulking' i.e. forcing by 

 means of blows from a hammer on a chisel-like 

 tool the edge of one thickness of plating against 

 the surface of the other. With the completion of 

 the riveting and caulking of the shell and the 

 concurrent advance of other features the vessel is 

 ready for launching. Preparations for this highly 

 important and critical part of the work have been 

 proceeding simultaneously with the finishing 

 touches to the shell. Launching ' ways' of heavy 

 timber have been laid down parallel to the keel 

 and at some little distance on each side of it 

 under the bilges of the vessel, and extending into 

 the water some distance beyond and below high- 

 water mark. A 'cradle' is then built under the 

 ship, the bottom of which is formed of smooth 

 timbers, or 'sliding ways,' resting upon the 'per- 

 manen t ways. ' Before launching, the rubbing faces 

 of both of the ways are well greased, and gradually 

 the weight of the ship is transferred from the ' keel- 

 blocks ' and bilge-blocks to the cradle and ways. 

 By a locking arrangement of the two ways the 

 tendency of the ship and cradle to glide down the 

 lubricated pathway is resisted until the proper 

 moment. When this arrives (at high-water usu- 

 ally) the ceremony of naming the vessel takes place, 

 the locking arrangement or ' dog-shore ' is knocked 

 away, and the vessel glides down the appointed 

 pathway with gradually increasing velocity until 

 checked by the resistance of the water or ' brought ' 

 to by check-ropes and weights on shore. As soon 

 as the vessel is ' water-borne ' the weight is taken 

 from the cradle, and it floats apart in pieces, which 

 are afterwards towed back to the shipyard. 



Although the vessel is now afloat, much 

 probably remains to be done. Frequently the 

 greater part of the deck-planking has to be laid 

 and cauiked, and the whole of the cabin appoint- 

 ments, previously prepared in the joiner's shop, to 

 be fitted up ; the wood ceiling which lines the 

 cargo-holds has to be laid, the masts have to be 

 put on board and erected, together with the spars, 

 sails, and rigging. In the case of a steam-vessel 

 the propelling machinery engines, boilers, shafting, 

 &c. and the various items of deck machinery 

 windlass, winches, steering-gear, &c., have all to be 

 placed and properly secured on the seatings pro- 



