Two torpedo gunboats (length 200 feet, beam 25 feet, moulded depth 13 feet 6 inches; displacement 520 tons) built by Laird Brothers of Birkenhead, for the Argentine Government, were fitted with two 19-inch by 28 and a half inches by 42-inch by 19 and a half inch stroke inverted-vertical triple-expansion surface-condensing marine engines, operating on steam supplied at 150 pounds per square inch by four marine locomotive boilers. Under normal conditions the boilers were worked with natural draught; but they could also be worked with forced draught if necessary. Armament; two 14-pounder Nordenfelt guns on the forecastle, one 8-pounder on the aft end of the poop, two 3-pounders mounted on the fore part of the poop, two Nordenfelt revolving cannon, four 18 inch torpedo tubes in the waist and one 18 inch torpedo tube in the stem.