38 STRUCTURE OF VESSELS AS AFFECTED 



There is one thing which nobody has touched on here, which seems to me in many cases 

 would contribute very largely to the safety of ships, and that is the installation of a com- 

 pressed air system. This is not a very difficult thing to do, particularly on a passenger 

 ship, where there are numerous decks. Something of that kind has been put in several of 

 our battleships, and it is a matter of great simplicity, as it can be combined with the fire pro- 

 tection feature and you can utilize the pipes, to a great extent at least, that are already in the 

 ship, and 'I think it is a matter which is worthy of very serious consideration. Probably on 

 a single-deck cargo-carrying ship it would not be easy to put in, but on a ship with several 

 decks, where the pressures could be graduated from the bottom up, it seems to me such a 

 large step toward a solution of the problem that it is worthy of very careful consideration. 

 Mr. Gatewood's suggestion of the application of steel hatches for fire protection would 

 tend to make this even more easy. 



Prof. Herbert C. Sadler^ Member of Council: — The whole question of whether a ves- 

 sel will remain afloat or sink really depends upon our definition of safety. We must make 

 certain assumptions, and I think the congress at present meeting in London will probably 

 come to some conclusions that will represent the results of the experience of all the nations 

 of the world, and so we may very properly take those as being the conditions that ought to 

 be fulfilled by vessels in order that they may float under certain conditions of flooding. 



The question is really a rather complicated one, 'because we can attack it from so many 

 points of view. In any ship we have varying permeabilities, as it has been called — that is, 

 when a compartment is flooded, that compartment may contain machinery, engines and 

 boilers or cargo of different densities, or passenger accommodations. We can average up 

 these permeabilities and make our flooding calculations accordingly. After we fix the per-" 

 meability of different compartments, then we ought to allow a margin of safety, to be 

 determined by the experience of people who are handling ships — naval architects and others 

 — ^but the margin of safety must be fixed in connection with the permeability. Or, as has 

 been done, we can assume the vessel will go down to the bulkhead deck under any con- 

 ditions, and then arbitrarily vary the permeability according to the type or size and speed 

 of the vessel. All these are factors which come into this question of flooding. The size 

 of the vessel, of course, is also important, and in general a larger and higher speed vessel 

 should have a greater percentage of freeboard than the smaller and lower speed type. From 

 my own point of view I feel that it is the more rational thing to fix an average permeability 

 in the cargo space and then allow a percentage of depth as freeboard, or a margin of safety 

 line, below which the vessel should never go under any conditions of flooding. 



With regard to the number of compartments, we must bear this in mind : a ship is built 

 for commercial purposes, and therefore, if we lay down a set of rules as to subdivision, etc., 

 that make it impossible of operation, the ship will not be built, and therefore it is an im- 

 portant thing to consider the commercial end of this question of subdivision. Vessels, I 

 think, will naturally divide themselves into those which will remain afloat with one, two, 

 or three compartments flooded, and if you come to a type where you are between the two 

 vessels, the one or two compartment vessel, you can overcome the difficulty perhaps by hav- 

 ing one compartment flooded and run the bulkheads up a deck higher, or if you have two 

 compartments flooded, run the bulkheads one deck lower. I think with some such scheme 

 as that we can work up practical vessels which could be operated commercially and still be 

 reasonably safe. 



