The was a class of submarine in the Imperial Japanese Navy (IJN), which served during the Second World War. The Type-A submarines were built to take a role of the command ships for submarine squadrons. For this reason they had equipment for a headquarters, better radio facilities and a floatplane.

Class variants The Type-A submarines were divided into four classes:

. The 5094th vessel class boats were not built and remained only a design.

Type-A (I-9 class)

Project number S35Ja. Their design was based on the Junsen III (I-7 class). Three boats were built in 1938-42 under the Maru 3 Programme (Boat # 35 - 36) and Maru 4 Programme (Boat # 138).

Boats in class Boat No. Boat Builder Laid down Launched Completed Results Fate 35 . The same shall apply hereinafter. Kure Naval Arsenal 25-01-1938 20-05-1939 13-02-1941 Sank USS Lahaina 12-12-1941 Sunk by at Kiska 13-06-1943. 36 Kawasaki-Kōbe Shipyard 07-06-1938 20-09-1939 31-10-1941 Sank Panamanian merchant ship Donerail 10-12-1941Sank USS Melvin H. Baker 05-06-1942Sank Panamanian merchant ship Atlantic Gulf 06-06-1942Sank RMS King Lud 08-06-1942Sank RMS Queen Victoria 28-06-1942Sank USS Express 30-06-1942Sank Greek merchantman Nymphe 06-07-1942Sank RMS Hartismere 08-07-1942Sank Dutch merchant ship Alchiba 09-07-1942Sank USS Samuel Gompers 30-01-1943Sank USS Gulfwave 01-03-1943Sank Norwegian merchantman Alcides 22-07-1943Sank Norwegian merchant ship Bramora 14-09-1943Sank USS Elias Howe 24-09-1943Sank Norwegian merchant ship Storvixen 01-10-1943Sank Norwegian merchantman Anna Knudsen 02-10-1943Sank RMS Congella 24-10-1943Sank or damaged unknown warship 02-07-1944 Sunk by and east of Saipan 04-07-1944. 138 Kawasaki-Kōbe Shipyard 10-04-1940 28-02-1941 16-05-1942 Sank Greek merchant ship George S. Livanos 20-07-1942Sank USS Coast Farmer 21-07-1942Sank USS William Dawes 22-07-1942Damaged 20-07-1943Damaged USS Matthew Lyon 11-08-1943 Lost in an accident or sunk by a mine near Funafuti January 1944.

Type-A Mod.1 (I-12 class)

Project number S35B. Five boats were planned under the Maru Tsui Programme (Boat # 620 - 621) and the Kai-Maru 5 Programme (Boat # 5091 - 5093). They were equipped with less powerful diesel engines which shortened the time needed to build them. Only one boat, , was completed to the original design. The I-13 and the later boats were converted to a new submarine class (I-13 class), because the number of I-400 class boats was reduced. Boats in class Boat No. Boat Builder Laid down Launched Completed Results Fate 620 Kawasaki-Kōbe Shipyard 05-11-1942 03-08-1943 25-05-1944 Sank USS John A. Johnson 30-10-1944 Sunk by minesweeper USS Ardent on 13-11-1944. 621 I-13 Kawasaki-Kōbe Shipyard 04-02-1943 Converted to the I-13 class in October 1943. 5091 I-14 Kawasaki-Kōbe Shipyard 18-05-1943 5092 I-15 Kawasaki-Senshū Shipyard 30-04-1943 5093 I-1 Kawasaki-Senshū Shipyard 24-06-1943

Type-A Mod.2 (I-13 class)

Project number S35C. Four boats were planned under the Maru Tsui Programme (Boat # 621) and the Kai-Maru 5 Programme (Boat # 5091 - 5093). However, four boats were converted to new submarine class (I-13 class), because a number of submarines of the I-400 class were cancelled. They had a large hangar and were equipped with bulges to be able to operate 2 × special Aichi M6A1 Seiran attack bombers. The headquarters institutions were removed.

Boats in class Boat No. Boat Builder Laid down Launched Completed Results Fate 621 Kawasaki-Kōbe Shipyard 04-02-1943 30-11-1943 16-12-1944 Sunk by , and aircraft from northeast of the Ogasawara Islands 16-07-1945. 5091 Kawasaki-Kōbe Shipyard 18-05-1943 14-03-1944 14-03-1945 Captured by 27-08-1945, decommissioned 15-09-1945, sunk as a target off the Hawaiian Islands 28-05-1946. 5092 I-15 Kawasaki-Senshū ShipyardKawasaki-Kōbe Shipyard (after launch) 30-04-1943 12-04-1944 Converted to a tanker submarine in June 1945;Senshi Sōsho Vol.88 (1975), p.272 90% complete; scrapped in 1945.5093 I-1 Kawasaki-Kōbe ShipyardKawasaki-Senshū Shipyard (after launch) 24-06-1943 10-06-1944 70% complete; Sunk by a typhoon on 18-09-1945; later salvaged and scrapped.

V21 Type Project number S48. Three boats were planned under the Kai-Maru 5 Programme. However, all boats were cancelled in late 1943, because the IJN turned its attention to the construction of in 1945.

Boats in class Boat No. Boat Builder Laid down Launched Completed Fate 5094 - 5096 Cancelled in 1943.

Characteristics Type Type-A (I-9) Type-A Mod.1 (I-12) Type-A Mod.2 (I-13) V21 TypeDisplacement Surfaced Submerged No data Length (overall) (waterline) Beam Draft Depth No data Power plant and shaft 2 × Kampon Mk.2 Model 10 diesels2 shafts 2 × Kampon Mk.22 Model 10 diesels2 shafts 2 × Kampon Mk.22 Model 10 diesels2 shafts 2 × Kampon Mk.2 Model 10 diesels2 shaftsPower Surfaced 12,400 bhp 4,700 bhp 4,700 bhp 11,000 bhp Submerged 2,400 shp 1,200 shp 600 shp 2,400 shpSpeed Surfaced Submerged Range Surfaced at at at at Submerged at at at at Test depth Fuel 878 tons 917 tons 917 tons 880 tons Complement 104 112 108 No data Armament (initial) • 6 × Torpedo tubes(6 × front)• 18 × Type 95 torpedoes• 1 × L/40 11th Year Type Naval gunCampbell, John Naval Weapons of World War Two p.191• 4 × Type 96 25mm AA guns • 6 × TTs (6 × front)• 18 × Type 95 torpedoes• 1 × L/40 11th Year Type Naval gun• 4 × Type 96 25mm AA guns • 6 × TTs (6 × front)• 12 × Type 95 torpedoes• 1 × L/40 11th Year Type Naval gun• 10 × Type 96 25mm AA guns • 6 × TTs (6 × front)• 18 × torpedoes• 1 × 140 mm Naval gun• 4 × 25mm AA guns Aircraft and facilities • Catapult and hangar• 1 × Watanabe E9W1 Slim seaplane • Catapult and hangar• 1 × Yokosuka E14Y2 Glen seaplane • Catapult and hangar• 2 × Aichi M6A1 Seiran floatplane • Catapult and hangar• 1 × floatplane

Footnotes

Bibliography , History of Pacific War Vol.17 "I-Gō Submarines", Gakken (Japan), January 1998, Rekishi Gunzō, History of Pacific War Vol.63 "Documents of IJN submarines and USN submarines", Gakken (Japan), January 2008, Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces", Gakken (Japan), March 2005, Model Art Extra No.537, Drawings of Imperial Japanese Naval Vessels Part-3, Model Art Co. Ltd. (Japan), May 1999, Book code 08734-5 The Maru Special, Japanese Naval Vessels No.13, "Japanese submarines I-13 class and I-400 class", Ushio Shobō (Japan), July 1977, Book code 8343-7 The Maru Special, Japanese Naval Vessels No.31, "Japanese Submarines I", Ushio Shobō (Japan), September 1979, Book code 68343-31 Senshi Sōsho Vol.88 Naval armaments and war preparation (2), "And after the outbreak of war", Asagumo Simbun (Japan), October 1975

See also Cruiser submarine