Two twin-screw torpedo boat "destroyers" (length180 feet; beam 18 feet 6 inches; contract speed 26 knots) the Havoc and the Hornet were fitted with twin inverted-vertical triple-expansion engines 18 inches by 26 inches by 39 and half inch by 18-inch stroke, the Havoc's boilers were of the locomotive type adopted by Messrs. Yarrow whilst the Hornet's were water-tube boilers, armament in both cases was; three torpedo tubes, one built into the bow, two on a turntable aft, one 12-pounder Hotchkiss gun, and another two, just abaft of the turtle-back forward, both vessels were being built to the order of the Admiralty by Messrs. Yarrow and Co., of Poplar.