page_title: Japanese cruiser Ibuki (1943)
section_title: Conversion
hierarchical_section_title: Japanese cruiser Ibuki (1943) / Conversion
caption_attribution_description: 日本海軍航空母艦「伊吹」解体の為旧佐世保海軍工廠にて撮影された写真。 Ibuki, Imperial Japanese Navy aircraft carrier, under dismantling operation at Sasebo Factory, Japan. October, 1946
context_page_description: The Japanese cruiser Ibuki was a heavy cruiser built for the Imperial Japanese Navy during World War II. The lead ship of her class of two ships, she was ordered to be converted into a light aircraft carrier in 1943 before completion to help replace the aircraft carriers sunk during the Battle of Midway in mid-1942. The conversion was delayed and finally stopped in March 1945 in order to concentrate on building small submarines. Ibuki was scrapped in the Sasebo Naval Arsenal beginning in 1946.
context_section_description: Ibuki's two aft turbine sets, the four aft boilers and the two innermost propeller shafts were removed with their propellers; the exhaust uptakes for the remaining boilers were trunked together into a downward-curving funnel on the starboard side of the hull. These changes left her with two turbines and four boilers producing 72,000 shp (54,000 kW). The reduced power meant that Ibuki's top speed was only 29 knots (54 km/h; 33 mph). The space made available was used for aviation gasoline tanks, additional fuel oil tanks, as well as bomb and torpedo magazines. The ship now could carry enough oil for an estimated range of 7,500 nmi (13,900 km; 8,600 mi) at a speed of 18 knots (33 km/h; 21 mph).
  As part of the conversion, the existing superstructure was razed, a new hangar deck was built above the existing upper deck and a full-length 205-meter (672 ft 7 in) flight deck was added. It had a maximum width of 23 meters (75 ft 6 in), two 13-by-11.6-meter (42.7 by 38.1 ft) aircraft elevators that serviced the single hangar and a small starboard island structure. The ship was bulged to improve her stability, which increased her beam to a maximum of 21.2 meters (69 ft 7 in). Ibuki's trials displacement increased to 14,800 metric tons (14,600 long tons) and the additional weight increased her draft to 6.31 meters (20 ft 8 in).
  Initially, the ship was to have a very light armament of only 22 triple 2.5-centimeter gun mounts, controlled by eight Type 95 fire-control directors, but this was modified in 1944 to substitute four 60-caliber 8 cm (3 in) Type 98 dual-purpose guns, mounted in two twin-gun turrets, and four 28-tube launchers for 12-centimeter (4.7 in) anti-aircraft rockets for six of the triple 25-millimeter gun mounts and two directors (now Type 4s). This gave the ship a total of forty-eight 25 mm guns in 16 triple mounts.
  At the top of the island, Ibuki was planned to have a 2-meter (6 ft 7 in) rangefinder and a Type 21 radar. In 1944, the radar was moved to a retractable mount in the flight deck near the bow and a Type 22 surface search and a Type 13 early-warning radar were going to be installed on the island. The ship retained the Type 93 hydrophone system.
  The ship's air group was intended to consist of 27 aircraft, 15 Mitsubishi A7M Reppū (Allied codename: "Sam") fighters and a dozen Aichi B7A Ryusei ("Grace") dive/torpedo bombers. They would be operated by the ship's complement of 1,015 officers and men.
caption: Ibuki in Sasebo, just before being scrapped, 22 October 1946
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