HAYBOX BOILERS FOR U BOATS.

Waikato Times, Volume 87, Issue 13269, 26 August 1916, Page 3 (Supplement)

HAYBOX BOILERS FOR U BOATS.

By H. C. Ferraby

Immensely technical though the sub--1 ject is, it would be foolish for anyone to shirk consideration of the problem which is most nearly to affect warship construction when we return to our peaceful vocations of preparing for war. Far and away mor 0 important than the question of "Dreadnought or submersible" will bo the question of Diesel or turbine" with quite possibly an unexpected shift of the wind into the quarter of electricity. Certainly the naval architects of the day are by no means blind to the possibilities of the motor-engine for the very largest class of warship, and presumably no twentieth century Board of Admiralty will be so muddie-headed as that oi Lord Melville in the early nineteenth, which solemnly put on record its belief that the adoption of steam instead oi sails "was calculated to strike a fata blow at the supremacy of the Empire." There was one man of that age who had the foresight and that was Hardy—Nelson's Hardy— who said: "You will see groat changes in naval architecture. Some people laugh at science, but science will alter the whole character ol the Navy." To-day we do not laugh at science. The motor-battleship has been a dream for a great many years, but it is now more than a dream. I was at a recent meeting of the Institution of Aayal Architects, when it was deliberately asserted by one speaker that the tlung was an engineering possibility. "Not a voice was raised against the assertion. At the same time in France the semi-official "Fleet Monitor" ha<= been discussing the same question and enlarging on the advantages of the Die-sel-engmed battleship, and, bv a curiou coincidence, a French Admiralty official has published a book in which he advocates mildly the abolition of the Diese' for submarines and its replacement by steam. The situation is not without its comicalities. Briefly summarised the contention o< engineering experts at present in regard to motor-engines foravarships is this: Motor-battleships are possible, motor battle-cruisers are possible, but not yet motor destroyers and light cruisers'are not possible

It trill strike ninny people as extremely curious that the larger ships should bo amenable to the innovation while the smaller ones are not. Usually progress is in the contrary direction, through small things to large. The objection in this case is due to the influence of speed on weight of engines. Destroyers and light cruisers must be very fast' To give them speed you must give them plenty of engine power. Steam engines give one horse power for even- thirtv pound? they weigh: Diesel engines give one horse power for every sixty pounds ap proximately. If you increase the weight you decrease the speed, or alternatively you build a larger ship, which is consequently not of the class you want. It is for this reason that marine engineer? are doubtful, in the present state of de°lopment of the Diesel engine, whether

the motor light craft are practicable. It is for much the same reason thn the motor battle-cruiser, again a ven fast type, whose main essential is her speed, cannot at present be considered more than a possibility of the future In the battleship, however, where speed and engine power are subservient to hitting capacity, equal power and speed can be obtained from motor engines as from steam without any increase in displacement.

Meanwhile, at the other end of the scale, wo have steam advocated to replace motors. M. Olivier Guiheneuc, in his "Dreadnought or Submersible " gives particulars of a new steam generator for use in undersea craft which is certainly interesting. It is, if I niav be thoroughly untechnical, a sort of a haybox cookery idea. The watertube boiler is surrounded by material which accumulates and stores up heat. On the surface the vessel is driven by steam generated by fire, petrol gas flames being used and when the submarine dives those furnaces are shut off, but the heat accumulated round the tubes continues indefin-

itely to generate more steam. The thing sounds fantastic, but it is stated to be actually in practical use. What is the reason for this change of face in regard to submarine propulsion? It is again a matter of speed. So Ion? as the submarine remains the slow craft that she is at present, so long as her submerged speed is round about eleven knots, she will remain a simple auxiliary to tlie surface squadrons with their twenty-fivo and thirty-five knot units The French -ideal is a submarine that can do thirty-two knots on the .surface and twenty-two submerged. Xo one has as yet come anywhere near to realisation of that ideal, and so long as the heavy weight of a double installation of elec-

trie motors and Diesel engines for submerged and surface propulsion respectively continues to be carried, it is ver\ doubtful that any such ideal can be obtained. Hence the search for-the "uni-

que" engine, some type which shall opcrate equally well on the surface and submerged. As I said in regard to destroyers, if you increase the power of your engines you increase the weight, and so increase the size of your ship. Xow the groat utility of the submarine is her invisibility when submerged, but a verv large ship under water, by reason of her displacement of water when she moves, is almost bound to betray her presence. Therefore, every effort must be made by inventors to discover an extremelv light-weight engine which will give high power, if the submarine is ever to approximate to the ideal. When thev have discovered that they will be faced with the further problem of discovering s

gun weighing about 25 tons which will be as destructive as the 15-inch

gun which weighs 106 tons. Then thev

will have to discover armour plate as effective as plates ten times their weight. Thereafter the era may begin when the submarine will have displaced the surface Dreadnought. But by that time you and I will have joined our fathers, and shall bo no more, concerned in these affairs.