UNSINKABLE SHIPS

Dominion, Volume 11, Issue 40, 10 November 1917, Page 8

UNSINKABLE SHIPS

LESSONS FROM THE "GREAT EASTERN" THE PROBLEM OF BULKHEADS The absolutely unsinkable ship is possible only if we deprive it of all its usefulness, unless, indeed, it is packed tightly with an uusinkable cargo—and tnen it is the contents, not tlie ship itself, that prevents its going to tlie bottom. Every ship nowadays is built of materials that are heavier than water. Vessels arts kept afloat by the exclusion of the water from the spaces within the hull devoted to the accommodation of passengers or freight. If the water is admitted to these, the vessel inevitably goes down. We can postpone tlie sinking by making these spaces as small as possible and separating them as completely as we can, but even then the ship can be sunk if an enemy possesses the means to fink it. Tt is somewhat strange, under these circumstances, says a writer in the engineering supplement of "The Times" to find that many people continue to put forward all kinds of proposals for rendering ships unsinkable. "A ship," he says, "will always remain afloat provided she has reserve'of buoyancy—that is to say, so long as the weight of water that would be displaced by the total volume of the ship is greater than her weight. It will help matters to consider two extreme cases. If a solid homogeneous log is just floating in water, it stands to reason that any part or parts of it can be destroyed without the remainder sinking. On the other hand, if an empty sliell is just afloat in the water, any break in the shell, however small, will bo sufficient to cause it to sink. A ship is neither a solid log nor an empty shell, but is something between the two. A ship is a shell, insido of which are all kinds of fittings, such as the structural parts, the passenger equipment, and so cn." The writer devotes considerable space to this question. It is possible so to build the water-tight compartments of a vessel that when water is admitted to one of these, she will capsize, although she will not sink. This has not infrequently happened. "It is safe to say." the writer concludes, "that the question of unsinkability of shins is closely connected with their stability, and that in the future ships will be relatively wider

than in the past." A Possibility. On the other hand, an American shipbuilding expert, ,T. Bernard Walker, asserts that the "unsinkable" ship is a possibility. .Apparently his definition of the term is "difficult to sink" or "unlikely to sink"; so he is really not at eerious odds with the "Times's" expert. He -writes in the "Scientific American": "Is it possible to build an unsinkable shin? It certainly is; for over half .1 century ago Brunei produced in the Great. Eastern a ship which was more entitled to 1)6 called 'unsinkable' than anv merchant ship which has been built from that time to this. Brunei was a technical renins. . . . The Great Eastern was "a magnificent ship, and she was built so well that, outside tho Navv. there never has b?en a ship that couln compare with her for protection against sinking. Po j;ood was slip that on one of her early voyages to New York, she ran on the' reefs at Jfontauk.' tearing a hole iii her bottom ten feet wide by eighty feet lonjr. and yet steamed safely down the Sound, anchored in Hempstead Harbour, and was there repaired by the caisson method without, going into dry dock. . . . Prom that date. 1858, to'the. present time there has been a steady deterioration in the protective elements of merchant ships. Brunei built his famous liner on the 'safety-first' principle. Since that time the commercial man, who is rarely an idealist, and generally very much die other way, has thrown out, one by one, those safety elements which Brunei incorporated in his ship, until to-day the chance of a ship surviving a hea.vy collision or the blow of a torpedo is about one in one hundred. "The naval constructors of the United States Navy have worked out a system of construction involving elaborately subdivided torpedo-defence spaces, which is so effective that they are -willing to guarantee and apply the system to merchant construction. They believe that they can turn out merchant ehips that would be proof against sinking by the torpedo. We have given some thought to this matter and submit, merely as a study, tho accompanying . . . plan of a freighter designed to pass through the submarine zone. To begin with, we have omitte<l the double skin —this for the reason that both skins would be burst in by a modern torpedo and the inner skin ivould merely furnish an additional number oS flying fragments, to be carried under hiuh velocity into the ship. The principle adonted is that of numerous transverse bulkheads, carried up to the upper or main deck of the ship, which deck is of steel and built thoroughly water-tight. The transverse bulkheading would be located very much closer together than the present practice—2o feet apart in vessels of 4000 to 7000 -tons, the widths increasing proportionately to the increase- in size of the shirr. ... It is nur belief that a ship built alone these lines with dnorless bulklmads, with light hatches, and vent, chambers that would bo blown open, allowing the escape of the pases, could withstand torpedo attack and receive one, and nossibly two, torpedoes without necessarily going to the bottom."