The torpedo boat destroyers H.M.S. Swordfish and Spitfire (length 200 feet, beam 19 feet 6 inches, draught 7 feet 9 inches; displacement 275 tons) fitted with 18 and three quarter inch by 27 and a quarter inch (2) by 28 inch by 18-inch stroke triple-expansion engines built by G. E. Belliss and Company, Birmingham, operating at 398 revolutions per minute with steam supplied at 200 pounds per square inch by eight Yarrow water-tube boilers, built by W. G. Armstrong, Whitworth and Company, Newcastle-on-Tyne, for the British Government, had just been commissioned. At the official three hours' trial of the Swordfish the engines indicated a mean of 4,750 horsepower at 398.7 revolutions per minute, whilst the Spitfire's engines indicated a mean of 4,506 horsepower at 398.8 revolutions per minute, the mean speed of the two vessels taken over three hours was 27.117 and 27.46 knots respectively. Both vessels were armed with two 18 inch revolving torpedo tubes; one 12-pounder gun' mounted on the top of the conning tower forward; and five 6-pounder guns.