The submarines were double-hulled medium-sized submarines of the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. They were derived from the . 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 L/40 gun and four 53 cm

torpedo tube A torpedo tube is a cylindrical device for launching torpedoes. There are two main types of torpedo tube: underwater tubes fitted to submarines and some surface ships, and deck-mounted units (also referred to as torpedo launchers) installed aboa ...

s for ten type 95

Long Lance The was a -diameter torpedo of the Imperial Japanese Navy (IJN), launched from surface ships. It is commonly referred to as the Long Lance by most modern English-language naval historians, a nickname given to it after the war by Samuel Eliot Mori ...

torpedoes. Most of these submarines were destroyed in combat, suffering from Allied

anti-submarine warfare Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are t ...

measures, and only survived the war.

Class variants

The ''Kaichū'' type submarines were divided into seven classes: * * * * * * *

''Kaichū I (Ro-11 class)''

Project number S7. In 1910s, the

(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 and . The ''Kaichū I'' is the submarine which jumboized the ''S Type'' submarines. *Boats in class

''Kaichū II (Ro-13 class)''

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

''Kaichū III (Ro-16 class)''

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

''Kaichū IV (Ro-26 class)''

Project number S18A. Improved model from the ''Kaichū III'' type. *Boats in class

''Kaichū V (Toku-Chū, Ro-29 class)''

Project number S18B. They were built for the

commerce raiding Commerce raiding (french: guerre de course, "war of the chase"; german: Handelskrieg, "trade war") is a form of naval warfare used to destroy or disrupt logistics of the enemy on the open sea by attacking its merchant shipping, rather than en ...

role. The IJN official designation of these boats was . *Boats in class

''Kaichū VI (Ro-33 class)''

Project number S30. They were planned as a prototype for a mass production submarines in the wartime under the Maru 1 Programme. *Boats in class

''Kaichū VII (Sen-Chū, Ro-35 class)''

Project number S44. The final design in the ''Kaichū'' series. They were equipped with a Freon air-conditioner, because the IJN took into consideration that they were to be active on the equator area too. The official IJN designation of these boats was , also called for short, or .
The IJN planned to build these boats under the following Naval Armaments Supplement Programmes: * 9 boats in the Maru Rin Programme (Boat # 201 - 209) * 12 boats in the Maru Kyū Programme (Boat # 385 - 396) * 15 boats in the Maru Tui Programme (Boat # 640 - 654) * 43 boats in the Kai-Maru 5 Programme (Boat # 5181 - 5223) However some of the boats were cancelled and their naval budgets, materials and staffs were transferred to the ''I-201'' class submarines. *Boats in class

Characteristics

Bibliography

*'', History of Pacific War Vol.17 I-Gō Submarines'', Gakken (Japan), January 1998, *''Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces"'', Gakken (Japan), March 2005, *''The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III'', Ushio Shobō (Japan), September 1980, Book code 68343-44 *''The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition"'', Ushio Shobō (Japan), February 1988, Book code 68344-36 *''The Maru Special, Japanese Naval Vessels No.133 Japanese Submarines II "Revised edition"'', Ushio Shobō (Japan), March 1988, Book code 68344-37 *''The Maru Special, Japanese Naval Vessels No.135 Japanese Submarines IV'', Ushio Shobō (Japan), May 1988, Book code 68344-39

References

{{DEFAULTSORT:Kaichu Submarine classes Submarines of the Imperial Japanese Navy