BUOYANCY AND STABILITY OF TROOP TRANSPORTS. 155 



Side-bunker bulkheads, whether watertight or not, always constitute a danger 

 to stability in merchant vessels where adequate means of quickly correcting a list 

 are not available. An underwater explosion on one side may cause a bunker on that 

 side to be flooded immediately and, generally, also the adjoining boiler-room. The 

 opposite bunker will not as a rule be flooded so quickly, even if the bunker-doors are 

 non-watertight and open, because usually the doors are choked with coal and the' 

 water can enter but slowly. The ship, therefore, at once takes a list, and although 

 a gradual equalization may take place, water is likely at the same time to filter into 

 adjacent compartments or spread over 'tween decks so that the stability may be de- 

 stroyed and the ship capsize before equalization in the bunkers can prevent it. In 

 such a case, then, the loss of the ship is directly due, not to the longitudinal bulk- 

 head on the damaged side, but to the intact bulkhead on the other side, and the dan- 

 ger is greater the more watertight that bulkhead is. In point of safety side bunk- 

 ers are useful only provided they are narrow, well subdivided, and watertight, and 

 then only in cases of minor damage, where the side bulkhead remains intact. It is 

 best, therefore, to avoid all such bulkheads in merchant vessels. 



The danger of side bunkers in passenger vessels became evident by the loss 

 of the Lusitania on May 7, 19 15. The Lusitania was going at about 18 knots speed 

 when she was hit almost simultaneously by two torpedoes on the starboard side 

 abreast of the boiler-rooms. One of the torpedoes hit near the bulkhead separat- 

 ing boiler-rooms i and 2. Lifeboat No. 5, which is about 160 feet aft of that bulk- 

 head, was destroyed by the blast of an explosion, but whether from the same or the 

 other torpedo is unknown. The ship at once took a list of about 15 degrees, un- 

 doubtedly due to the presence of the side bunkers, and this list gradually and 

 rapidly increased, due to infiltration of the water, especially through open sidelights. 

 At the same time the bow was sinking deeper into the water than the stern. In 

 less than twenty minutes after the explosion the ship capsized and sank. The initial 

 list was so great that it was practically impossible to lower the boats on the port side, 

 although the sea was calm. Due to this fact and the short time available before the 

 ship went down, about 1,200 lives were lost out of a total of about 1,950 persons on 

 board the ship. 



Center-line bulkheads are no less objectionable and dangerous in merchant 

 vessels than in warships. A calculation shows that, in the Leviathan, flooding of 

 the two engine-rooms on one side will produce a list of 19 degrees, and in the 

 Mount Vernon of 21 degrees, while in the George Washington, where there is no 

 center-line bulkhead, flooding of the main engine-room will leave the ship upright, 

 the sole efifect being a sinkage of about 25-^ feet with a total change of trim by 

 the stern of about 5 feet. 



A more insidious source of danger is found in many merchant steamers — 

 even such as are ostensibly subdivided on the transverse system — due to the exist- 

 ence of "shifting bulkheads" fitted longitudinally inside transverse bunkers, usually 

 at or' near the center line and often on top of a tunnel. These bulkheads, which 

 are fitted for the purpose of preventing the coal from shifting, are non-watertight 



