THE NAVY.

Press, Volume LXIV, Issue 19258, 13 March 1928, Page 7

THE NAVY.

A NEW MINE-LAYER. TURBINES AND DIESELS. (MOli OOE OW* COEEESPONDIXT.) LONDON, January 25. H.M.S. Adventure is the first British warship to be designed expressly for wine-laying. During the war a great many craft were employed for sowing mines—battleships, cruisers, destroyers, submarines, merchantmen, and "even aeroplanes; but there was no ship built specially for this work. The new ship has turbine machinery for high speed and Diesel-electric drive for cruising. When the war losses of all belligerents came to be analysed it was found that the mines had claimed as manv victims as, if not more than, anv other weapon of naval warfare. Mines accounted for 24 per cent, of the capital ships and cruisers that were sunk, 57 per cent, of the destroyers, and 27 per cent, of the submarines. Taking British losses alone, about 400 warships and auxiliary craft and 1,121.000 tons of merchant shipping were destroyed by mines. In view of these figures it is not surprising (writes the "Daily lelegraph" naval correspondents that the Admiralty should have decided to pay special attention to the future development of mine-laying warfare. As she was not meant to fight other ships, the armament was restricted to four 4.7 in quick-firers, with many lighter guns. The weight thus saved has been utilised for the storage of mines, of which about 1000 are carried. These deadly weapons are conveyed on rails froin the magazines to the stern of the. ship, whence they are dropped into the sea through two ports. It may be added that the present type of British naval mine is infinitely more efficient and destructive than the type in use on the outbreak of the war; further, that the mine stowage capacity of the Adventure is four times greater than that of any previous mine-laying ship. The Engines. Parsons turbines of 40,000 h.p., fed with steam from oil-burning boilers, drive the vessel at a maximum speed of 27$ knots. The steam plant, however, is brought into operation only when a high speed is desired. When she is cruising independently or in company with the fleet the turbines are cut out, and the ship is then propelled by her Diesel-electric machinery, which develops 4200 h.p., sufficient for a speed of 14 knots.

There are two Diesel oil engines, each coupled direct to a generator of the three phase alternating current system, with a pressure of 1100 volts between phases, the current from which drives two high-speed induction motors, eacn turning a propeller shaft at 160 revolutions per minute. If necessary, both motors can be operated from one generator. The motors are speeded up by reactance resistence starters. A new type of automatic booster is fitted to provide for over-excitation of the alternators under conditions of overload caused by rough weather. Motors and alternators are controlled by oilbreak switches operated from • the control platform in the Diesel engine compartment. Simplicity the' Keynote.

By merely turning a hand-wheel the engineer in charge is able to control the entire propelling plant on either side of the ship. Simplicity is the keynote of the whole installation,-which is understood to incorporate features-new to Diesel-electric practice. The operation and performance of every unit in the plant is recorded by instruments provided for the purpose. In effectj therefore, the engine-room of Adventure serves as a laboratory for the study of Diesel-electric dynamics, with a view of their possible further development for naval requirements. 'The only external evidence of the ship's unique system of propulsion is affordby a' trunk placed abaft the second funnel, through ' which the exhaust gases from the Diesel motors are carried off.

Admiralty Up-to-date. While official details of the Adventure's trials have yet to be published, they are known to have been highly successful. The perfect functioning of the machinery under all conditions proves that British engineering' skill has solved in practical fashion all the technical difficulties involved. There can be no doubt that, were it not for the restraints imposed by shortage of funds the Navy would long since have taken the lead in developing the internal-combustion system for the propulsion of warships. In the years following the war some exceedingly useful research and experimental work was carried out in the Admiralty engineering laboratory at Wert Drayton, the fruits of which have been mast beneficial to British progress in the manufacture of oilengines. In view of the widespread interest evoked bv the rapid advance of the motor-ship, as shown by the latest shipbuilding returns, it is reassuring to learn that the Navy is keening abreast of progress in this important branch of engineering.