BUOYANCY AND STABILITY OF TROOP TRANSPORTS. 147 



tive main bulkheads at the level of the fire-room floor, and often a tunnel with a 

 door at each end is fitted through the main transverse bunker usually fitted in the 

 forward end of the forward boiler-room, so that coal may be drawn directly from 

 the nearest reserve bunker. Such doors, putting two of the largest compartments 

 in the ship in connection with each other and being necessarily open during long 

 periods, while the ship is at sea, constitute a serious menace and should be closed 

 under war conditions. This necessitates hoisting the coal from the reserve bunkers 

 on to the bulkhead deck, whence it can be dumped into one of the regular bunkers, 

 an arrangement which was adopted in several ships during the war. 



The transverse main bunker bulkheads in passenger steamers are generally non- 

 watertight with non-watertight sliding bunker doors and should be disregarded in 

 considering the watertight subdivision, but even if such bulkheads are of water- 

 tight construction, it is best not to rely on them, since the doors will normally be 

 open when the ship is under steam. 



The following further recommendations are essentially an abstract of those 

 given for large mail and passenger vessels under war conditions by a committee ap- 

 pointed by the Institution of Naval Architects in 191 7 to inquire into the effects of 

 underwater explosions on the structure of merchant ships.* 



Firemen's passages should be permanently closed up and all openings from the 

 engine-rooms into shaft tunnels should be abolished, access to tunnels being pro- 

 vided through watertight trunks abaft the engine-room bulkhead. If these recom- 

 mendations are not carried out, the engine-room tunnel doors should be quick-closing 

 and capable of operation from the bulkhead deck or a deck above. 



Doors fitted in main bulkheads on the 'tween deck below the bulkhead deck 

 cannot always be dispensed with without great inconvenience to the service and 

 without radical alterations. It is a fact, however, that such doors are very dan- 

 gerous in cases where a ship takes a sudden and great list, whereby water is ad- 

 mitted to the 'tween deck and tends to spread forward and aft (Empress of Ire- 

 land). It is advisable, therefore, to close those doors, to secure them so that they 

 cannot be opened, and to provide additional exits to the decks above where necessary. 



The committee further recommended that all side scuttles situated below the 

 first deck above the bulkhead deck be closed up and sealed. It may here be added 

 that all side lights below the bulkhead deck should be not only closed but also pro- 

 tected by steel plates or strong watertight covers, as they are otherwise liable to be 

 broken by the force of the underwater explosions. 



Valves should be fitted on all sanitary discharges at the ship's side such as will 

 prevent water passing inboard through them when the vessel has a considerable 

 trim or list. 



The upper ends of ash or rubbish shoots, etc., opening on decks below the bulk- 

 head deck should be provided with watertight covers, which should always be in 

 place when the shoots are not in use. 



♦Report of May 8, 1917. Institution Naval Architects, 1918, p. xxxvii. 



