The Kii-class battleship was a planned class of four fast battleships to be built for the Imperial Japanese Navy (IJN) during the 1920s. Only two of the ships received names. They were intended to reinforce Japan's "eight-eight fleet" of eight battleships and eight battlecruisers after the United States announced a major naval construction program in 1919. However, after the signing of the Washington Naval Treaty in 1922, work on the ships was suspended; one pair was cancelled in November 1923 and the other in April 1924.

Design and background

By 1918, the Navy had gained approval for an "eight-six" fleet of eight battleships and six battlecruisers, all ships under eight years old. However, having four large battleships (two each of the Nagato-class battleship and Tosa-class battleshipes) and four Amagi-class battlecruisers on order put an enormous financial strain on Japan, which was spending about a third of its national budget on the Navy. Despite this, the IJN gained approval of the "eight-eight-eight" plan in 1920 after American President Woodrow Wilson announced plans in 1919 to re-initiate the 1916 plan for ten additional battleships and six battlecruisers. The Japanese response was to plan the construction of eight additional fast battleships in the Kii and the Number 13 classes. Designed by Captain Yuzuru Hiraga, the Kii class was based largely on the preceding Amagi-class battlecruisers, which were in turn based on a less-armored Tosa-class design. The only major difference between the Kiis and Amagis was their speed and armor—the Amagis were faster, and the Kiis had a thicker belt. Despite this lineage, the Kiis were classified as "fast battleships" by the Japanese, as they had decided to end the distinction between "battleship" and "battlecruiser."

Description

The ships had a length of 234.9 m between perpendiculars and 250.1 m overall. They had a beam of 30.8 m and a draft of 9.7 m. The normal displacement of the battleships was 42600 t. The class was intended to be equipped with four Gijutsu-Hombu geared steam turbines, each of which drove one propeller shaft. The turbines were designed to produce a total of 131200 shp, using steam provided by 19 Kampon oil-fired water-tube boilers, to reach a maximum speed of 29.75 kn. The primary armament of the Kii class was ten 45-caliber 41 cm guns in five twin-gun turrets, two fore and three aft of the superstructure. This gun fired a 1000 kg shell at a muzzle velocity of 790 m/s. The secondary battery consisted of 16 single 50-caliber 14 cm guns was mounted in casemates in the superstructure. The manually operated guns had a maximum range of 19750 m at an elevation of +35° and fired at a rate up to 10 rounds per minute. The ships' anti-aircraft defenses consisted of four single 45-caliber 12 cm 10th Year Type anti-aircraft guns mounted around the single funnel. Each of these guns had a maximum elevation of +75° and a maximum rate of fire of 10–11 rounds per minute. They could fire a 20.41 kg projectile with a muzzle velocity of 825 - 830 m/s to a maximum height of 10000 m. The Kii class was also fitted with eight 61 cm above-water torpedo tubes, four on each broadside. The ships would have been protected by a waterline belt of armor 292 mm thick, sloped 15° outwards at the top to increase its ability to resist penetration at short range. The belt armor was designed to be able to defeat 16 in shells from a distance of 12000 –. The main battery turrets and barbettes would have had between 229 - 280 mm of armor plating, and the conning tower would have had been protected by armor 356 mm thick. The decks would have been 120 mm thick. The Kii-class battleships would have had a torpedo bulkhead 75 mm thick, which connected at the top to a 38 mm splinter deck beneath the main deck.

Construction

Two ships were ordered on 12 October 1921, and two more were ordered later that year. Kii was allocated to Kure Naval Arsenal, Kure, with a projected completion date of November 1923, and Owari (尾張, an ancient province) was allocated to the Yokosuka Naval Arsenal, Yokosuka, with completion in September. Two more unnamed ships, Numbers 11 and 12, were assigned to Kawasaki in Kobe and Mitsubishi in Nagasaki, respectively. The ships' keel laying was stopped on 5 February because the terms of the Washington Naval Treaty that forbade the construction of all battleships over 35000 LT. Numbers 11 and 12 were formally canceled on 19 November 1923; Kii and Owari followed on 14 April 1924.

Footnotes