The twin-screw first-class torpedo boat Ariete (length 147 feet 6 inches, beam 14 feet 6 inches, draught 5 feet; trial speed 26.2 knots) was fitted with two 14 and a half inch by 24 and a quarter inch by 15 inch stroke inverted vertical compound engines operating with steam supplied by two Thornycroft water-tube boilers, built by Messrs. John I. Thornycroft and Co. to the order of the Spanish Government.