The construction of a new twin-screw torpedo gunboat (length 230 feet, beam 27 feet; displacement 810 tons) designed by Mr. W. H. White had been entrusted to Messrs. J. I. Thornycroft and Co., Chiswick, by the Admiralty under the Naval Defence Act. The principal difference between this vessel and others of the same class was that it was fitted with a Thornycroft water-tube boiler, and that it developed 4,500 indicated horsepower instead of 3,500 indicated horsepower as in the case of the other vessels of the same class that had been fitted with marine locomotive boilers.