A steam launch (length 30 feet, beam 5 feet 8 inches, draught 18 inches forward and 2 feet aft; trial speed 8 miles per hour), was fitted with a four and a half inch by four and a half inch stroke, single cylinder inverted-vertical simple marine engine operating with steam supplied at 70 pounds per square inch by a vertical boiler 2 feet 6 inches in diameter by 3 feet high, three-bladed propeller 22 inches in diameter, 3 feet 6 inches pitch; built by Messrs. Yarrow and Hedley, Poplar. Simplicity in construction was achieved by forging the piston rod guides and the rod itself in one piece the engine frames and cylinder were also a single casting.