AN AMERICAN "COMMERCE DESTROYER."

Otago Witness, 14 December 1893, Page 25

AN AMERICAN "COMMERCE DESTROYER."

The triple-screw protected cruiser Minneapolis has been launched for the Government of the United States at Messrs Cramp's Yard, Philadelphia. She is a steel, four- funnelled vessel, and is intended to serve as a " commerce destroyer." The chief dimensions and particulars of her are — Length on loadline, 412 f t; moulded beam, sSft 2in ; mean normal draught, 23ft ; displacement, 7550 tons ; indicated horse-power, 21,000 ; extreme speed, 22 knots ; coal capacity with normal draught, 750 tons ; maximum coal capacity, 2000 tons ; radius of action at 10 knots, 26,240 miles ; guaranteed sea speed, 21 knots. The magazines, engine roomß, and vitals are protected by an overall steel deck, varying from 2Jin to 4in thick. One screw is immediately before the rudder, on the centre line of the ship, and is a four-bladed screw of lOdeg more pitch than the two others, which are placed one on each quarter, 15ft forward of the middle screw and 4ft 6iu above it. These are triple-bladed. Each screw has independent triple- expansion vertical inverted engines. It is stated that with the middle screw alone a speed of 15 knots can be attained ; with the quarter screws alone a speed of nearly 19 knots. The cylinders are of 42in, 59in, and 92in diameter, for high, intermediate, and low pressure respectively, and 42in stroke. _ Steam is supplied by eight main boilers, placed in four separate compartments, and carrying 1601b per square inch as their working pressure. They are double ended, 21ft Sin long and lift Sin in diameter, with eight 42in corrugated furnace flues, and 1128 steel 2}in tubes. The total heating surface is 43,2(39 square feet, and the total grate surface 1285 square feet. The estimated number of revolutions for extreme speed is 129 per minute. The subdivisions of the vessel, which is furnished with a lam, are so arranged as to form a complete double hull below the water lino.