POWERFUL SHIP

Evening Post, Issue 149, 20 December 1935, Page 8

POWERFUL SHIP

SPECIAL PROBLEMS SOLVED

The Achilles, a sister ship of the Leander, Ajax, Neptune, and Orion,' is a much more powerful cruiser than the Diomede and Dunedin, though it is still in the light class. The Leanders were the answer made to- a most difficult problem set naval" architects by the post-war, tonnage limitation agreements, and have been described ai triumphs of design under new restrictive conditions. In accordance with the decisions' and agreements of the Washington Conference, 1922, 10,000 ton cruisers of ihe Kent and London classes .(the Australia and Canberra are in • these classes) were built, with, 321 knots speed, eight 8-inch guns, four 4-inch anti-aircraft guns, and lighter' armament, but when the aggregate tonnage of cruisers to be built was-fixed-by the London Naval Treaty of 1930 a new problem was set, not of building to a permissible maximum tonnage of each vessel, but to design for a'combination of minimum displacement ■ and maximum- power to obtain as manyvessels as possible of the types to be built. The. designing of the Leander class extended over several years, and when, after design after design, of major construction and of-the last detail, had been examined, compared, amended, and, one of them, accepted, there was reproduced in the 7000-ton Leanders a close-approximation of the power of the 10,000-ton Kent and London classes. In one main particular they differ: the main armament has been lightened from eight 8-inch guns to eight 6-inch guns, but this is largely, if not wholly (the decision is for experts, not for uninformed,-opinion), balanced by additions in the way of aircraft (each of the 7000-ton cruisers carries a seaplane and catapult),, anti-aircraft armament and protection, and more advanced control systems. The maximum speed, 32J knots, is slightly higher than that of. the 10,000-tonners, though the horsepower is reduced;fromißo,ooo; t0,72,900. " '~~' ' . SAVING'WEIGHT. :'-:':.;;: ;/ Brassey's Naval Annual lor 1933 dealt with the Leander class in a special section, much of which referred to the extreme care which was taken by the naval architects to reduce weight, not mercy by tons, but by pounds and even ounces. Special steel was - used in large quantities to meet structural stresses with a minimum weight of hull, welding" replaced riveting in certain sections, and aluminium sheets and bars, with small castings of-light alloy, were used for a variety of purposes, such as minor bulkheads/ventilation trunks, cabin linfcgs, . racks, cupboards,- etc. Considerable weight was saved by using plywood in place of solid wood in furniture.* A very substantial saving in weight was effected by using a white hardwood for deck planking instead of teak* and this class-, of wood was also used instead of mahogany for. portions of furniture to save cost. Other items which contributed to reduction to weight were the use of cast steel of better quality, watertight doors made of thin, embossed steel, and davits made tubular instead of solid. Savings, amounting to tons in the total, were' even effected by discarding old painting methods arid turning to new. One coat of aluminium paint was used on certain interior surfaces which would have otherwise taken two or three coats of oil paints, and where fine finishes were required' aluminium paint replaced the- usual red-lead grounding. Though the furnishing in all quarters is an advance on that of earlier cruisers, the selection of materials made for a Substantially lesser total weight. COMPARISON WITH PRESENT NZ CRUISERS. A comparison of the main dimensions and armament of the Achilles and the Diomede (and Dunedin) is as follows:— Achilles. Diomede. Displacement . 7,140 tons' 4,850 tonr Horse-power ~ 72,000 40 000 Speed (max.) 32M> knots 29 knots Overall-length 554 ft Gin ' 472 ft 9in Kight 6-lnch Six G-men Four 4ln A.A. Three 4in A.A. Two quadruple Four triple 21in . ' 2JIn torpedo torpedo tubes tubes " / Seaplane —. The bare comparison does not give any true indication of the power of the two types, for though neither the Diomede nor the Dunedin is an old ship (they were completed in. 1922 and 1919 respectively, and' have sines then gone through the full refit and. modernisation), there have been great advances in armament design and effectiveness, gun control, and communication systems. ■ . Writing in the "Daily Telegraph" ot an. inspection of the type ship, Lean* der, Hector By water, ■ after dealing with the new pattern of 6in.guns and rapid fire, up to sixty: shells.: pef minute, the improved high-angle gun» and the new arrangement of torped* tubes and other armament, said that tht ■protection is equal, if not superior, to that of the considerably-heavier light cruisers, and in addition a much smaller target is presented. Electrical power is employed more extensively than in any other British warship. It operates the capstans, the steering engines, boat and seaplane hoists, pumps, andy, in conjunction with hydraulic power, the gun turrets.; Power is" supplied by four 1000-ampere dynamos. Almost the only drawback, he continued, was the high cost. The total bill for the Leander amounted Ho £1.667,819 tons, of which the hull absorbed £83,000, the machinery £430,000, and the guns and mountings £470,000. In later ships of the class modifications would, it was hoped, materially reduce the cost. . -.. ■■'.'":

A man smuggling pork into. Germany from Poland was shot dead by frontier guards and another carrying butter was wounded.