Kaichū type submarine


The Kaichū type submarine 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.
Several variants existed. From 1934 to 1944, the K6 type and the K7 type were built. They were equipped with a 8 cm/40 3rd Year Type naval gun| L/40 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.

Class variants

The Kaichū type submarines were divided into seven classes:
Project number S7. In 1910s, the Imperial Japanese Navy bought a license of Schneider-Laubeuf design submarine. The IJN used the design as model and built the S Type submarine, the and. The Kaichū I is the submarine which jumboized the S Type submarines.
BoatBuilderLaid downLaunchedCompletedFate
Submarine No. 19
Kure Naval Arsenal25-04-191725-10-191731-07-1919 as Submarine No. 19Renamed Ro-11 01-11-1924. Decommissioned 01-04-1932.
Submarine No. 20
Kure Naval Arsenal25-04-191701-12-191718-09-1919 as Submarine No. 20Renamed Ro-12 01-11-1924. Decommissioned 01-04-1932.

''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.
BoatBuilderLaid downLaunchedCompletedFate
Submarine No. 23
Kure Naval Arsenal14-09-191826-08-191930-09-1920 as Submarine No. 23Renamed Ro-13 01-11-1924. Decommissioned 01-04-1932.
Submarine No. 22
Kure Naval Arsenal14-09-191831-03-191917-02-1921 as Submarine No. 22Renamed Ro-14 01-11-1924. Decommissioned 01-09-1933.
Submarine No. 24
Kure Naval Arsenal12-06-192014-10-192030-06-1921 as Submarine No. 24Renamed Ro-15 01-11-1924. Decommissioned 01-09-1933.

''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.
BoatBuilderLaid downLaunchedCompletedFate
Submarine No. 37
Kure Naval Arsenal18-11-192022-04-192129-04-1922 as Submarine No. 37Renamed Ro-16 01-11-1924. Decommissioned 01-09-1933.
Submarine No. 34
Kure Naval Arsenal24-09-192024-02-192120-10-1921 as Submarine No. 34Renamed Ro-17 01-11-1924. Decommissioned 01-04-1936.
Submarine No. 35
Kure Naval Arsenal20-10-192025-03-192115-12-1921 as Submarine No. 35Renamed Ro-18 01-11-1924. Decommissioned 01-04-1936.
Submarine No. 36
Kure Naval Arsenal09-09-192028-12-192015-03-1922 as Submarine No. 36Renamed Ro-19 01-11-1924. Decommissioned 01-04-1936.
Submarine No. 38
Yokosuka Naval Arsenal28-07-191926-10-192001-02-1922 as Submarine No. 38Renamed Ro-20 01-11-1924. Decommissioned 01-04-1934.
Submarine No. 39
Yokosuka Naval Arsenal28-07-191926-10-192001-02-1922 as Submarine No. 39Renamed Ro-21 01-11-1924. Decommissioned 01-04-1934.
Submarine No. 40
Yokosuka Naval Arsenal22-01-192115-10-192110-10-1922 as Submarine No. 40Renamed Ro-22 01-11-1924. Decommissioned 01-04-1934.
Submarine No. 41
Yokosuka Naval Arsenal22-01-192115-10-192128-04-1923 as Submarine No. 41Renamed Ro-23 01-11-1924. Decommissioned 01-04-1935.
Submarine No. 42
Sasebo Naval Arsenal21-04-191908-12-191930-11-1920 as Submarine No. 42Renamed Ro-24 01-11-1924. Decommissioned 01-04-1935.
Submarine No. 43
Sasebo Naval Arsenal19-02-192017-07-192025-10-1921 as Submarine No. 43Renamed Ro-25 01-11-1924. Decommissioned 01-04-1936.

''Kaichū IV (Ro-26 class)''

Project number S18A. Improved model from the Kaichū III type.
BoatBuilderLaid downLaunchedCompletedFate
Submarine No. 45
Sasebo Naval Arsenal10-03-192118-10-192125-01-1923 as Submarine No. 45Renamed Ro-26 01-11-1924. Decommissioned 01-04-1940. Scrapped 1948. Her anchor is displaying at Yokosuka Naval Base.
Submarine No. 58
Yokosuka Naval Arsenal16-07-192122-07-192231-07-1924 as Submarine No. 58Renamed Ro-27 01-11-1924. Decommissioned 01-04-1936. Scrapped 1948.
Submarine No. 62
Sasebo Naval Arsenal10-11-192113-04-192230-11-1923 as Submarine No. 62Renamed Ro-28 01-11-1924. Decommissioned 01-04-1940. Scrapped 1948.

''Kaichū V (Toku-Chū, Ro-29 class)''

Project number S18B. They were built for economic-warfare role. The IJN official designation of these boats was Special Purpose-Medium Type submarine.
BoatBuilderLaid downLaunchedCompletedFate
Submarine No. 68
Kawasaki-Kōbe Shipyard02-06-192105-12-192215-09-1923 as Submarine No. 68Renamed Ro-29 01-11-1924. Decommissioned 01-04-1936.
Submarine No. 69
Kawasaki-Kōbe Shipyard27-06-192118-01-192329-04-1924 as Submarine No. 69Renamed Ro-30 01-11-1924. Decommissioned 01-04-1942. Scrapped 1945.
Submarine No. 70Kawasaki-Kōbe Shipyard25-09-192115-02-1923 as Submarine No. 70Lost in an accident off Awaji Island 21-08-1923. Salvaged and scrapped October 1923. Her materials were used for Ro-31.
Kawasaki-Kōbe Shipyard20-12-192425-09-192610-05-1927Decommissioned 25-05-1945. Scuttled off Sasebo 05-04-1946.
Submarine No. 71
Kawasaki-Kōbe Shipyard24-10-192119-03-192321-05-1924 as Submarine No. 71Renamed Ro-32 01-11-1924. Decommissioned 01-04-1942. Scrapped 1945.

''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.
BoatBuilderLaid downLaunchedCompletedResultsFate
Kure Naval Arsenal08-08-193310-10-193407-10-1935Sank Australian merchant ship 07-08-1942Sunk by and RAF patrol aircraft off Port Moresby 29-08-1942.
Mitsubishi-Kōbe Shipyard25-04-193412-12-193531-05-1937Sunk by and near Russell Islands 06-04-1943.

''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 Medium Type submarine, also called for short, Medium Type or Submarine-Medium Type.

The IJN planned to build these boats under the following Naval Armaments Supplement Programmes:
However some of the boats were cancelled and their naval budgets, materials and staffs were transferred to the I-201 class submarines.
Boat No.BoatBuilderLaid downLaunchedCompletedResultsFate
201Mitsubishi-Kōbe Shipyard09-10-194109-06-194225-03-1943Sunk by near of Espiritu Santo 25-08-1943.
202Mitsubishi-Kōbe Shipyard07-03-194214-10-194227-05-1943Sunk by north of Saipan 13-06-1944.
203Sasebo Naval Arsenal09-10-194130-06-194230-06-1943Damaged 22-01-1944Sunk by near of Santa Cruz Islands 22-01-1944.
204Mitsubishi-Kōbe Shipyard20-06-194224-12-194224-07-1943Disappeared after 19-11-1943.
205Mitsubishi-Kōbe Shipyard08-08-194206-03-194312-09-1943Sunk by and east of Wotje Atoll 03-02-1944.
206Mitsubishi-Kōbe Shipyard08-08-194206-03-194328-09-1943Sunk by north of Marshall Islands 16-02-1944.
207Mitsubishi-Kōbe Shipyard06-10-194205-05-194326-11-1943Sank 03-10-1944Sunk by south of Okinawa 23-03-1945.
208Sasebo Naval Arsenal27-04-194225-10-194231-08-1943Sunk by northeast of Marshall Islands 10-06-1945.
209Mitsubishi-Kōbe Shipyard06-10-194205-06-194316-12-1943Damaged 21-02-1945Sunk by aircraft from off Iwo Jima 27-02-1945.
385Mitsui-Tamano Shipyard14-02-194211-11-194213-09-1943Sunk by near of Enewetak 16-06-1944.
386Mitsubishi-Kōbe Shipyard20-10-194221-07-194311-01-1944Sunk by, and aircraft from south of Truk 01-05-1944.
387Mitsui-Tamano Shipyard13-06-194223-04-194319-02-1944Damaged 29-01-1945Sunk by aircraft from near of Oki Daitō 29-04-1945.
388Mitsubishi-Kōbe Shipyard28-12-194220-08-194331-01-1944Sunk by northeast of Palau 26-09-1944.
389Mitsubishi-Kōbe Shipyard17-03-194315-10-194331-03-1944 Sunk by northwest of Saipan 14-07-1944.
Sunk by northwest of Saipan 18-07-1944.
390Mitsui-Tamano Shipyard16-11-194203-08-194319-05-1944Sunk by.
391Mitsui-Tamano Shipyard18-02-194327-11-194331-07-1944Sank USS LST-577 11-02-1945Decommissioned 30-11-1945. Sunk as target off Gotō Islands 01-04-1946.
392 - 395Cancelled in 1943.
396Mitsui-Tamano Shipyard05-08-194323-04-194430-09-1944Sunk by west of Luzon 07-02-1945.
640 - 644Cancelled in 1943.
645
Mitsui-Tamano Shipyard02-12-1943 as Ro-7505-07-194415-11-1944Sunk by and near of Oki Daitō 09-04-1945.
646 - 654Cancelled in 1943.
5181 - 5223Cancelled in 1943.

Characteristics