Amagi-class battlecruiser

Design for the Amagi class
Class overview
Builders	Kure Naval Arsenal Yokosuka Naval Arsenal Kawasaki, Kobe Mitsubishi (Nagasaki Shipyard & Machinery Works), Nagasaki
Operators	Imperial Japanese Navy
Preceded by	Kongō class
Succeeded by	Design B-65
Built	1920–1922
Planned	4
Completed	1 (converted into an aircraft carrier)
Cancelled	3
Lost	1
Scrapped	3
General characteristics
Type	Battlecruiser
Displacement	41,217 t (40,566 long tons) (normal) 47,000 t (46,260 long tons) (full load)
Length	251.8 m (826 ft)
Beam	30.8 m (101 ft)
Draft	9.5 m (31 ft)
Installed power	131,200 shp (97,800 kW) 19 water-tube boilers
Propulsion	4 shafts; 4 steam turbines
Speed	30 knots (56 km/h; 35 mph)
Range	8,000 nmi (15,000 km; 9,200 mi) at 14 knots (26 km/h; 16 mph)
Complement	1,600
Armament	5 × twin 41 cm (16.1 in) guns 16 × single 14 cm (5.5 in) guns 6 × single 12 cm (4.7 in) AA guns 8 × 61 cm (24 in) torpedo tubes
Armor	Belt: 250 mm (9.8 in) Deck: 95 mm (3.7 in) Conning Tower: 75–360 mm (3.0–14.2 in) Torpedo bulkheads: 73 mm (2.9 in) Barbettes: 230–280 mm (9.1–11.0 in)

The Amagi class (天城型, Amagi-gata) was a series of four battlecruisers planned for the Imperial Japanese Navy (IJN) as part of the Eight-eight fleet in the early 1920s. The ships were to be named Amagi, Akagi, Atago, and Takao. The Amagi design was essentially a lengthened version of the Tosa-class battleship, but with a thinner armored belt and deck, a more powerful propulsion system, and a modified secondary armament arrangement. They were to have carried the same main battery of ten 41 cm (16.1 in) guns and been capable of a top speed of 30 knots (56 km/h; 35 mph).

Limitations imposed by the 1922 Washington Naval Treaty prevented the class from being completed as designed. However, the treaty had a limited allowance for hulls already under construction to be converted into aircraft carriers. Amagi and Akagi were both intended for conversion, but an earthquake damaged the hull of Amagi so extensively that the ship was scrapped. Akagi was reconstructed as an aircraft carrier and served with distinction as part of the Kido Butai during the Second World War, participating in the Japanese attack on Pearl Harbor before being sunk at the Battle of Midway.