Japanese battleship Aki

Aki (安芸 (戦艦)) was a semi-dreadnought battleship built for the Imperial Japanese Navy (IJN) during the first decade of the 20th century. She was the second battleship built in Japan and the first to use steam turbines. The ship was named for Aki Province, now a part of Hiroshima Prefecture. The ship saw no combat during World War I. Aki was disarmed and sunk as a target in 1922–24 in accordance with the terms of the Washington Naval Treaty of 1922.

Background
The Satsuma class was ordered in late 1904 under the 1904 War Naval Supplementary Program during the Russo-Japanese War. Unlike the previous pre-dreadnought battleships, they were the first battleships ordered from Japanese shipyards. They were originally designed with a dozen 12 in guns, but had to be redesigned because of a shortage of guns in Japan and to reduce costs.

Design and description
The ship had an overall length of 492 ft, a beam of 83 ft, and a normal draft of 27 ft. She displaced 20100 LT at normal load. The crew consisted of 931 officers and enlisted men.

Aki was fitted with a pair of Curtiss steam turbine sets using steam from 15 Miyabara water-tube boilers. The turbines were rated at a total of 24000 shp for a design speed of 20 kn. The ship reached a top speed of 20.25 kn during her sea trials from 27740 shp. She carried enough coal and oil to give her a range of 9100 nmi at a speed of 10 kn. Unlike her half-sister, she had three funnels.

The ship was completed with four 45-caliber 12-inch 41st Year Type guns in two gun turrets, one each fore and aft of the superstructure. They fired 850 lb armor-piercing (AP) shells to a maximum range of 22000 m. The intermediate armament consisted of six twin-gun turrets equipped with 45-caliber Type 41 10-inch guns, three turrets on each side of the superstructure. Her heavy intermediate armament of guns larger than 9 in is why the ship is considered to be a semi-dreadnought.

Aki's secondary armament consisted of eight 45-caliber 6-inch 41st Year Type guns, mounted in casemates in the sides of the hull. The ship was also equipped with eight quick-firing (QF) 40-caliber 12-pounder 12-cwt guns and four 28-caliber 12-pounder QF guns. In addition, the battleship was fitted with five submerged 18 in torpedo tubes, two on each broadside and one in the stern.

The waterline main belt of the Satsuma-class vessels consisted of Krupp cemented armor that had a maximum thickness of 9 in amidships. It tapered to a thickness of 4 in at the ends of the ship. A 6 in strake of armor protected the casemates. The barbettes for the main guns were 7 - 9.5 in thick. The armor of Aki's main gun turrets had a maximum thickness of 8 in. The deck armor was 2 - 3 in thick and the conning tower was protected by six inches of armor.

Construction and career
Aki, named for Aki Province, was laid down at Kure Naval Arsenal on 15 March 1906. She was launched on 15 April 1907, but construction was suspended for about five months after the decision was made on 26 November to install steam turbines on Aki and the armored cruiser JAPANESE ARMORED CRUISER Ibuki. Akis turbines were already behind schedule and the suspension allowed the less valuable ship to be completed first, and changes made to its turbines after testing were also incorporated into Akis turbines. Aki was finally completed on 11 March 1911 and her first captain was Tatsuo Matsumura.

When World War I began in August 1914, Aki was refitting at Kure Naval Arsenal. She was assigned to the 1st Battleship Squadron upon the completion of her refit and remained with it until she was transferred to the 2nd Battleship Squadron in 1918. The ship was disarmed at Yokosuka in 1922 to comply with the provisions of the Washington Naval Treaty, stricken from the Navy List during 1923 and converted into a target ship. Aki was sunk by the battlecruiser JAPANESE BATTLESHIP Kongō and the battleship JAPANESE BATTLESHIP Hyūga on 2 September 1924 in Tokyo Bay. Two of her 10-inch gun turrets were installed as coastal artillery batteries on Jōgashima island to protect Tokyo Bay.