CONDITIONS AFFECTING DESIGN. 



295 



Fig. 289 shows the dock and the centre of buoyancy in the 

 same position as in Figs. 287 and 288, but the centre of gravity 

 is on the stable side, and if any internal or external force was 

 able to list the dock so far over it would right itself. 



The relative initial stability of the three Figs. 287, 288, 289, 

 exclusive of the stability of the ship, and purely in consequence 

 of their internal construction, is therefore 1, 4, and 49. 



Figs. 412, 413, 41 4, 1 show a pontoon dock constructed in 

 accordance with Mr. Alex. Taylor's letters patent for the Tyne 

 Pontoon and Dry Docks Company, Wallsend. 



Fig. 290 is a longitudinal view of the pontoon. Fig. 201 

 is a plan. Fig. 292 is a half cross-section and end view, 



FIG. 290. 



FIG. 291. 



showing the keel-blocks supported on three longitudinal girders, 

 G, F, and G 1 . These girders are stiffened by intercostal plates, 

 A, on every third frame. Stanchions are fitted to the inter- 

 mediate frames. The frames throughout are 31 inches from 

 centre to centre. The transverse gusset-plates in the tank G 

 are on every third frame, but in the tanks D and E are only on 

 every sixth frame. 



The frames between the gusset - plates are fitted with 

 stanchions. The longitudinal water-tight girders are shown 

 by F, G, H, I, K. Three transverse bulkheads divide the 

 pontoon tanks into four longitudinal parts, as shown on the plan 

 (Fig. 291), forming altogether twenty-eight separate tanks. The 

 plan also shows that the main tanks terminate some distance 



1 Engineer ing, vol. xlvi. p. 136 ; and Transactions of the North East Coast Institute 

 of Engineers and Shipbuilders. 



