the improved fuel efficiency resulting from superheated steam, the four boilers included economizers to further extend the ships' range by preheating incoming feedwater. The main steam turbines were manufactured by New York Shipbuilding in the case of the ships built by that yard. However, as in the Farraguts, the main turbines had single reduction gearing and no cruising turbines, limiting their efficiency. Armament There were extensive discussions about the armament, the /25 caliber anti-aircraft (AA) gun being favored as being easy to work and train in a fast moving and lively type of ship. The other candidate was the 5-inch/51 caliber surface type, being very powerful but all but useless against aircraft. It was a discussion made more interesting as the 5-inch/38 caliber dual purpose gun became available in the early 1930s and the Ordnance Department favored it rather strongly. The 5-inch/38 caliber gun was simply a 5-inch/25 caliber gun with the same projectiles and a longer barrel, but significantly increased range against both air and surface targets. The class was originally built with eight Mk 12 guns in four Mark 22 single purpose (surface action only) twin enclosed mounts; the single purpose mounts were adopted to save weight. Anti-aircraft protection was provided by two quadruple 1.1-inch (28 mm) mounts; in the 1930s this was considered sufficient. Although the Porters had the same eight torpedo tubes as the Farraguts, a full set of reloads was carried. The class was initially equipped with the Mark 11 or Mark 12 torpedo, which were replaced by the Mark 15 beginning in 1938. The heavy armament proved top-heavy, and aircraft were becoming a greater threat, so during World War II on most of the class, mounts 51 and 54 were replaced with dual purpose (surface action and air action) twin mounts, and the original 1.1-inch guns were replaced with 40 mm Bofors and 20 mm Oerlikons. In some ships, mount 52 was replaced by a quadruple 40 mm mount, and mount 53 became a single 5 in/38 cal dual purpose mount. Additional 40 mm guns were added amidships along with 20 mm weapons. In most ships, four K-gun depth charge throwers were added to augment the as-built pair of depth charge racks. In some cases (DD-357, DD-359, DD-360) late in the war, the torpedo tubes, two K-guns, and one depth charge rack were landed, to accommodate additional light AA armament, for a total of