146 



BUOYANCY AND STABILITY OF TROOP TRANSPORTS. 



y^/.T. B.H. 



'/■//.■/■. 

 CE.NTEH OF Explosion 



36 FT. 



B.H. Deck 



1m 



Centeh of" Explosion 



w. T B.H. 



KtEL 



Fig. 1. — Stepped Bulkhead. 



their main object to prevent the water from entering compartments other than those 

 directly and unavoidably flooded by an accident. 



In merchant vessels steps in bulkheads involve a danger in addition to that just 

 explained, due to the fact that the frames almost invariably pass non-watertight 

 through all decks below the bulkhead deck. When otie of the compartments adjacent 

 to a stepped bulkhead is flooded, and provided the step is situated below the water- 

 line, water is liable to filter through the deck at the frames. The cement filling 

 usually applied along the sides of the deck cannot be relied upon to keep tight under 

 a considerable head of water. Thus the integrity of the stepped bulkhead is de- 

 stroyed. The remedy is to fit stapling around the frames in that part of the deck 

 which belongs to the bulkhead. 



Recesses in bulkheads are not objectionable from this point of view as they are 

 usually watertight at the bounding decks. 



The danger of fitting doors in the main transverse bulkheads of troop trans- 

 ports is enhanced by the difficulty of controlling the doors at all times. This may be 

 due partly to the overcrowded condition liable to occur in troop transports, partly 

 to the impossibility of obtaining a highly trained personnel for all such vessels 

 under the stress of war. Great care should, therefore, be bestowed on this matter, 

 and no doors should be allowed in main transverse bulkheads below the bulkhead 

 deck, but this rule is not followed in passenger steamers. Doors are found partly 

 on a low level as between engine and boiler-rooms, partly on a high level, notably 

 on the deck just below the bulkhead deck. When such vessels are taken over for 

 service as troop transports all doors in transverse bulkheads on a low level in the 

 engine and boiler-rooms should be permanently closed. This, of course, renders 

 communication and inspection more difficult and many engineers for this reason 

 strongly object to it. It is, however, a fact that, in some of the largest American 

 transports used during the war, those doors were always closed when at sea with- 

 out serious detriment to the service. 



In most transoceanic passenger steamers the hold just forward of the boiler- 

 rooms is used as a reserve coal bunker. Often two compartments of the fore hold 

 are so used. Coal is drawn from the reserve bunkers through doors in the respec- 



