Under the terms of the Washington Naval Treaty the US Navy was restricted to 135,000 tons of aircraftcarriers, and so could only build a further 14,700 tons of carriers after the completion of Lexington, Saratoga, Ranger, Yorktown and Enterprise. Thus in 1935 an improved version of the Ranger was ordered, also with modest speed and light armour but big aircraft capacity. The opportunity was taken to eradicate the worst faults of the Ranger, and the new carrier was given a proper island superstructure and better compartmentation.
The USS Wasp (CV.7) was commissioned in April 1941, and from the autumn of that year was in the Atlantic on training duties. Late in March 1942 she went to the Mediterranean to ferry RAF Spitfires to Malta. At the beginning of July she left San Diego for the Pacific and took part in the Guadalcanal landings, where her aircraft flew more than 300 sorties. She missed the Battle of the Eastern Solomons as she had been detached to refuel, and she returned to Noumea to take on board a consignment of fighter aircraft for the US Marines on Guadalcanal. Early in the afternoon of 15 September 1942 the Wasp flew off her fighters, but shortly afterwards she was hit by three torpedoes fired by the Japanese submarine I-19. Two of the torpedoes struck her on the port side near the aviation gasoline tanks, while the third Port profile of the Wasp. The ship was very quickly gutted by fire and explosions, which proved impossible to contain as the torpedo detonations had also ruptured the fire mains. In less than an hour the order to abandon ship was given, and she continued to burn for another 3 hours; finally the destroyer Lansdowne was ordered to sink her, and four torpedoes were fired.
The Wasp proved the least battleworthy of all American carriers, and her loss provided important lessons for the future. A board of enquiry showed that the majority of the damage was caused by the third torpedo-hit, for the first two hits had left the machinery and auxiliary power undamaged. However, the shock of the explosions and the 'whip' of the hull had knocked out electrical switchboards and the damage control organization. Thereafter a series of subsidiary explosions of bombs, torpedoes, ammunition and aircraft fuel tanks wrecked the ship.
Specification USS Wasp (CV.7)
Displacement: 14,700 tons standard, 20,500 tons full load
Dimensions: length 225.93m (741 ft 3 in) overall; beam 24.61 m (80 ft 9 in); draught 8.53m (28ft 0 in)
Machinery: 2-shaft geared steam turbines delivering 55950kW (75,000shp)
Speed: 29 knots
Armour: belt 102 mm (4 in); main and lower decks 38 mm (1.4 in)
Armament: (1942) eight 127-mm (5-in) AA, four quadruple 27.94-mm (1,1-in) AA and 30 20-mm AA guns
Aircraft: (1942) 29 fighters, 36 divebombers and 15 torpedo-bombers
Complement: 2,367 officers and enlisted