A steam launch (length 56 feet, beam 7 feet 6 inches, draught 3 feet 9 inches, 2 feet 9 inches aft; trial speed 10.38 knots) was fitted with two 7-inch diameter inverted-vertical marine engines operating at 260 revolutions per minute with steam suppled at 90 pounds per square inch by a cylindrical marine return tubular boiler, built by Edwards and Symes of Cubitt Town for W Walker of London.