SIAM’S NAVAL GROWTH

Evening Star, Issue 22032, 18 May 1935, Page 24

SIAM’S NAVAL GROWTH

NEW SPEED BOATS Siam has made a further Interesting addition to her navy by ordering a third hatch of three C.M.B.’s (coatal, motor boats) from Thornycroft’s, London. These famous little craft were first built in 1916, The firm has now completed nearly 130 of them, including those built during the war (says the , Melbourne ‘Argus’)- Armed with torpedoes capable of sinking a battleship, and carrying mine-laying and anti-sub-marine apparatus, these armoured “pocket” destroyers areamrhaps the most spectacular of modern war machines. Fifty-five feet long and weighing 14 v tons when fully loaded,- they can smash their way through the open sea at almost 50 miles an hour. Hurtling directly toward an enemy at this terrific water speed, they present an extremely difficult target. As soon as they get within range of their objective a torpedo is released tail first over the stern, and the helm is, put hard over. The boat then turns and twists in an exciting fashion, hurling clouds of spray high in the air in its attempts to avoid a direct hit. The deadly torpedo is left to continue its course,, which was set by pointing the C.M.B. directly amidships of the target. - Let us step on board one of these scouts of the sea. In appearance she is not unlike a submarine, with her armoured conning tower set amidships. The controls are similar to those used m the modern motor car, with instruments grouped on two dashboards and a spoked steering wheel for the pilot, who is protected from spray by a low windscreen. Among the bewildering collection of “gadgets” we seo a Morse signalling lamp, a torpedo director, and an electric horn. Mounted aft are two troughs, in each of which is an 18in torpedo carried on rails which extend beyond the stern Carried in brackets on each side of the hull are two 4001 b depth charges for prowling submarines. There arenbfo two double Lewis guns mounted fore and aft, and strangc-looking apparatus for emitting smoko screens. Below in the engine room we see two powerful Thornycroft engines of the vee--12 type, each developing 475 h.p. at 1,600 revolutions a minute. Both consume about a gallon a minute from the 400-gallon fuel tanks, giving a range around 200 miles at full throttle. Another small four-cylinder auxiliary motor is installed amidships. When used for cruising purposes this engine gives a range of about 750 miles ai

seven knots. Under its power jt is possible to proceed within striking distance of the objective. Then the mam engines can be started. The main engines are started m an unusual manner. A button is pressed on the control tower, causing a valve to open and permitting compressed air at 3001 b pressure to pass along piping to the cylinders, picking up on its way a charge of petrol vapour from a Ki-gas vaporising unit. 0 If we care to crawl along on our hands and knees under the control tower we shall find the wireless cabin, a tiny compartment equipped with a sending and receiving set capable of transmitting over a range of 100 miles. Near by are two canvas cots and space for the stowage of gear, including an anchor weighing 701 b. The engineer is provided with a bucket seat between the engines, it being impossible for anyone to stand when the snip is travelling at speed. Looking at the C.M.B. from the wharf once more, we notice that she appears curiously “nose heavy.” This is intentional on the part of her designers, to give her stability when she is “ planing.” As she gets under way the bow gradually lifts until, when sufficient speed has been attained, the hull is planing on her stern and the formv'rt 's no longc steadied bv the water* At rest her draught is 3ft 9in, onl a mu throttle only 2ff remains bf tb" wn*"" Despite this light draught it is pos•ub e to make a lull turn in about five lengths with the throttle wide open. This speed and mobility make these water comets a formidable foe to a fleet of modern warships, each worth many times the value of a C.M.B. Nine foreign countries have already purchased C.M.B.’s, including France and the United States.