Kaichū type submarine

Class overview
Name:	Kaichū type submarines
Builders:	Kure Naval Arsenal Sasebo Naval Arsenal Yokosuka Naval Arsenal Kawasaki Shipbuilding Mitsui Engineering & Shipbuilding Mitsubishi Heavy Industries
Operators:	Imperial Japanese Navy
Subclasses:	Kaichū I (Ro-11 class) Kaichū II (Ro-13 class) Kaichū III (Ro-16 class) Kaichū IV (Ro-26 class) Toku-Chū/Kaichū V (Ro-29 class) Kaichū VI (Ro-33 class) Sen-Chū/Kaichū VII (Ro-35 class)
Built:	1917-1944
In commission:	1919-1945

The Kaichū type submarine (海中型潜水艦, Kaichū-gata sensuikan^?) submarines were double-hulled medium sized submarines of the Imperial Japanese Navy during World War II. They were derived from the Kaigun-shiki Chū-gata Sensuikan (海軍式中型潜水艦, Navy Medium Type submarine^?).

Several variants existed. From 1934 to 1944, the K6 type (Ro-33 Class) and the K7 type (Senchū, Ro-35 Class) were built. They were equipped with a 3.0 inch (76.2 mm) gun and four 53 cm torpedo tubes for ten Type 95 Long Lance torpedoes.

Most of these submarines were destroyed in combat, suffering from Allied anti-submarine warfare measures, and only the Ro-50 survived the war.

The Kaichū type submarines were divided into seven classes:

Project number S7. In 1910s, the Imperial Japanese Navy (IJN) bought a license of Schneider-Laubeuf design submarine. The IJN used the design as model and built the S Type (Schneider Type) submarine, the Ha-9 and Ha-10. The Kaichū I is the submarine which jumboized the S Type submarines.

Project number S18. The Kaichū II had an increased range compared with the Kaichū I, and the turning torpedo tubes were removed.

Project number S18. Their project number was the same as in the Kaichū II type submarine, however their performance was improved.

Project number S18A. Improved model from the Kaichū III type.

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