40 STRUCTURE OF VESSELS AS AFFECTED 



Apparently Mr. Gatewood scorns horizontal watertightness. I am glad Mr. Dickie has come 

 forward with a design in which he relies so much upon the horizontal watertight compart- 

 ments, because I have several times advocated in the past for some of these very large 

 vessels the fitting of a watertight deck forward and aft. One of the great dangers after 

 damage, forward or aft, is the pronounced change of trim, and if in any way you can confine 

 the water horizontally, the change of trim is reduced. You avoid the necessity of putting 

 water in at the other end. I have been met by the statement that it is not commercially pos- 

 sible to fit watertight decks. It would seem to me with these large liners — these very large 

 vessels, there is in the neighborhood of the water-line a practical line of demarcation between 

 the inhabited part of the vessel and the part of the vessel devoted to cargo principally, and 

 it should be possible to make that line of demarcation watertight and to protect the integ- 

 rity of the watertight deck by enclosures running up above the bulkhead line. I hope Mr. 

 Gatewood will give that matter attention after consideration of Mr. Dickie's paper. Mr. 

 Dickie has spent his lifetime in commercial work, and he would not advocate horizontal 

 watertight subdivision unless he believed it commercially practicable. 



Mr. Alden W. Welch, Visitor: — There is one point I would like to raise — one not 

 generally familiar — and that is the use of the boiler flue gases of a ship as a protection 

 against fires on shipboard. I believe this question has come up before the Institution of 

 Naval Architects of Great Britain. It seems to me such a simple scheme that, if practicable, 

 it is well worth developing; and I would like to know whether it has been considered by 

 members of this Society. In port the flue of the donkey boiler can be used ; therefore, there 

 is protection always at hand. At sea the funnel of the main boilers would be tapped. The 

 equipment in the Harker system, which is the British system, patented for this service, con- 

 sists of a De Laval turbine driving a fan, and a combined washer and cooler which uses 

 sea water for cleansing the gases, and then there is the piping, etc., for distributing the 

 gases. 



Flue gases consist of about 80 per cent nitrogen, something like 10 per cent CO2, 

 probably at most 1 per cent of the poisonous carbon monoxide (CO), and about 9 per cent 

 of oxygen. As 15 per cent of oxygen is required to support combustion, flue gas is inert. 



One difficulty, perhaps, is that flue gas is so light, being about 1.05 as compared with 

 air. In the Navy, carbon tetrachloride has been used experimentally with some success and 

 that liquified gas is about five times as heavy as air. Its action would, therefore, be much 

 more rapid than that of flue gas under gravity conditions only; but by the use of a fan I 

 do not see why the latter could not be blown into the hold as quickly. 



Flue gas is always available, and its use for fire extinguishing purposes would not 

 interfere with the operation of the ship as is the case when steam is used for choking 

 flames. The flue-gas system is worthy of consideration. 



Naval Constructor Joseph H. Linnard, Member of Council: — I note the statement 

 in Mr. Dickie's paper as follows : "There would be twelve bulkheads extending from the 

 inner bottom to the upper deck. These would be absolutely watertight, without doors or 

 openings whatever." I think most of us who have been engaged in building ships, espe- 

 cially men-of-war, know the great desirability of avoiding the use of watertight doors 

 or similar openings through bulkheads, that are supposed to be watertight. Such watertight 

 doors, even though fitted originally with great accuracy, and when tested found to be in per- 



