page_title: Myōkō-class cruiser
section_title: Design
hierarchical_section_title: Myōkō-class cruiser / Design
caption_attribution_description: English: Picture of Japanese heavy cruiser Myōkō, 1931. Русский: Японский тяжёлый крейсер «Мёко», 1931 год.
context_page_description: The Myōkō-class cruisers were a series of four heavy cruisers built for the Imperial Japanese Navy in the late 1920s. Three were lost during World War II.
  The ships of this class displaced 11,633 tons, were 201 metres long, and were capable of steaming at 36 knots. Their main armament were ten 20 cm/50 3rd Year Type naval guns in five twin turrets which were complemented by a heavy torpedo armament; at the time, this was the heaviest armament of any cruiser class in the world. They were also the first cruisers the Japanese Navy constructed that exceeded the limit set by the Washington Naval Treaty.
context_section_description: The Myōkō class displaced 13,500 t (13,300 long tons), with a hull design similar to the preceding Aoba-class cruiser. The displacement was substantially more than the designed 2/3 trial displacement of 11,850 t (11,660 long tons), a consequence of the demand to put as much as possible on a hull limited by the Washington Naval Treaty, and were likely unintentional as it adversely affected the seekeeping qualities and endurance of the class. They were 203.8 metres (669 ft) long with a beam of 19.5 metres (64 ft), and a draft of 6.36 metres (20.9 ft). Propulsion was by 12 Kampon boilers driving four sets of single-impulse geared turbine engines, with four shafts turning three-bladed propellers propelling the ship to 35.5 knots (65.7 km/h; 40.9 mph). Design endurance was 8,000 nautical miles however the increased weight issues reduced it to 7,000.
  Protection was superior to the preceding Aoba-class and accounted for about 16 percent of trial displacement. A 102 mm (4 in) side belt that ran along 123 m (404 ft) of the ship's length and 35 mm (1.4 in) armored deck protected the magazine and machinery spaces and 76 mm (3 in) protected the turret barbettes; however, the turrets only had 25mm splinter protection and the bridge was unarmored. Following innovations pioneered in Yubari, the armor belt was made an integral part of the hull structure to reduce weight. A torpedo bulkhead consisting of two 29 mm (1.1 in) plates with a total thickness of 58 mm (2.3 in) extended inwards from the bottom of the armor belt and curved to meet the bottom of the double hull. It was calculated that it was sufficient to withstand an explosion of 200 kg (441 lb) of TNT.
  As originally constructed, the class was armed with a main battery of ten 200 mm (7.9 in) 20 cm/50 3rd Year Type naval guns mounted in 5 twin turrets, the heaviest armament of any heavy cruiser in the world at the time. Secondary armament initially were 12 cm/45 10th Year Type dual purpose guns in six single mounts. Short-range Anti-aircraft defense was provided by two 7.7mm machine guns. Torpedo armament was unusually heavy compared to the cruisers of other nations at the time, with 12  carried in fixed single launchers inside the hull. They were also equipped with a single aircraft catapult and aircraft for scouting purposes.
caption: Myōkō at anchor, 1931.
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