The Commodoro Py, the second of a pair of twin-screw torpedo boats (length 150 feet, beam 14 feet 6 inches; contracted speed 25 knots) built Messrs. John I. Thornycroft for the Argentine Republic passed a very successful speed trial at the Lower Hope on the 29th of April 1891. The Commodoro Py was armed with the then new 18-inch Whitehead torpedo, and three quick-firing guns capable of penetrating a 4-inch steel plate.