The was a class of submarine in the Imperial Japanese Navy (IJN) which served during World War II. The Type-B submarines were similar to the Type-A apart from not having the headquarters installation.

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

. The 5115th vessel-class submarines were not built and remained a design only.

Type-B (I-15 class)

Project number S37. Twenty boats were built between 1937 and 1944 under the Maru 3 Programme (Boats 37 - 42) and Maru 4 Programme (Boats 139 - 152).

+Boats in class Boat No. Boat Builder Laid down Launched Completed Fate 37 . Kure Naval Arsenal 25 January 1938 7 March 1939 30 September 1940 Sunk by near San Cristóbal on 10 November 1942. 38 Yokosuka Naval Arsenal 18 April 1938 19 July 1939 24 January 1941 Sunk by and maritime patrol aircraft at Nouméa on 19 August 1943. 39 Mitsubishi, Kōbe Shipyard 15 March 1938 16 September 1939 28 April 1941 Sunk by in the Gilbert Islands on 25 November 1943. 40 Kawasaki, Kōbe Shipyard 7 January 1939 24 February 1940 15 July 1941 Missing near Tarawa after 27 November 1943. Possibly sunk by aircraft from on 29 November 1943. 41 Yokosuka Naval Arsenal 8 December 1938 24 November 1939 27 September 1941 Missing near the Hawaiian Islands after 24 February 1942, most likely due to a diving accident. 42 Mitsubishi, Kōbe Shipyard 3 February 1939 8 June 1940 15 October 1941 Missing near Espiritu Santo after 23 August 1943. Possibly sunk by on 25 August 1943. 43 The dummy for the naval budget of the . 139 Kure Naval Arsenal 7 June 1939 10 April 1940 6 November 1941 Missing east of the Philippines after 25 October 1944. Possibly sunk by on 26 October 1944. 140 Sasebo Naval Arsenal 5 July 1939 6 June 1940 24 February 1942 Sunk by and in the Maldives at on 12 February 1944. 141 Mitsubishi, Kōbe Shipyard 25 September 1939 17 December 1940 6 February 1942 Sunk by north of Rabaul at on 17 May 1942. 142 Yokosuka Naval Arsenal 20 September 1939 29 September 1940 27 February 1942 Sunk by south of Sabtang Island at on 26 July 1944. 143 Kure Naval Arsenal 7 June 1939 17 September 1940 28 February 1942 Sunk by a British mine at Singapore on 13 October 1942. Raised and scrapped between August 1959 and February 1960. 144 Yokosuka Naval Arsenal 6 December 1939 13 March 1941 30 May 1942 Sunk by at Attu Island on 13 May 1943. 145 Sasebo Naval Arsenal 20 January 1940 17 December 1940 26 April 1942 Sunk by and USS PC-1135 northeast of Wotje Atoll on 24 March 1943. 146 Mitsubishi, Kōbe Shipyard 21 February 1940 1 May 1941 10 June 1942 Lost in an accident at Truk on 26 September 1942. Salvaged and repaired starting 29 December 1943. Later, lost in another accident at Iyo Nada on 13 June 1944. Salvaged and scrapped starting 28 June 1953. 147 Sasebo Naval Arsenal 9 January 1941 24 September 1941 31 August 1942 Sunk by at Penang Island on 13 November 1943. Salvaged on 4 December 1962. 148 Mitsubishi, Kōbe Shipyard 2 September 1940 24 September 1941 31 August 1942 Sunk by and south of Tarawa on 22 November 1943. 149 Yokosuka Naval Arsenal 4 December 1940 1 November 1941 30 September 1942 Converted to a Kaiten mother ship on 1 September 1944. Decommissioned on 30 November 1945, blown up (along with Ha-106) off the Gotō Islands on 1 April 1946 as part of Operation Road's End. 150 Kure Naval Arsenal 7 December 1940 22 October 1941 10 March 1943 Converted to a Kaiten mother ship on 9 September 1944. Sunk by and north of Palau, on 19 November 1944. 151 Sasebo Naval Arsenal 19 June 1941 15 April 1942 31 January 1943 Sunk by east of Luzon on 13 November 1944. 152 Sasebo Naval Arsenal 19 June 1941 15 April 1942 22 April 1943 Sunk by west of Makin at on 16 November 1943. 153 The dummy for the naval budget of the Yamato-class battleships

Type-B Mod.1 (I-40 class)

Project number S37B. Six boats were planned under the Maru Kyū Programme (Boats 370 - 375), all boats were completed. On the outside this class looked the same as the I-15 class; however, they were built from high-tensile strength steel and equipped with diesel engines of a simpler design.

+Boats in class Boat No. Boat Builder Laid down Launched Completed Fate 370 Kure Naval Arsenal 18 March 1942 10 November 1942 31 July 1943 Missing after 22 November 1943. 371 Kure Naval Arsenal 18 March 1942 10 November 1942 18 September 1943 Sunk by east of the Philippines at on 18 November 1944. 372 Kure Naval Arsenal 18 March 1942 10 November 1942 3 November 1943 Sunk by southwest of Palau at on 23 March 1944. 373 Sasebo Naval Arsenal 27 April 1942 25 October 1942 5 November 1943 After completion, converted to a carrier for a Daihatsu-class landing barge. Sunk by north of Truk at on 15 February 1944. 374 Yokosuka Naval Arsenal 11 June 1942 5 March 1943 31 January 1944 Converted to a Kaiten mother ship on 22 October 1944. Sunk by an aircraft from southeast of Okinawa at on 29 April 1945. 375 Sasebo Naval Arsenal 15 July 1942 6 March 1943 28 December 1943 Sunk by east of the Philippines on 29 October 1944.

Type-B Mod.2 (I-54 class)

Project number S37C. Twenty-one boats were planned under the Maru Kyū Programme (Boats 627 - 636) and Kai-Maru 5 Programme (Boats 5101 - 5114). Eighteen boats were cancelled in late 1943, because the IJN was setting the as 1945's main submarines.

Boats in class Boat No. Boat Builder Laid down Launched Completed Results Fate 627 Yokosuka Naval Arsenal 1 July 1942 4 May 1943 31 March 1944 Damaged on 25-10-1944 (?)This result is estimated with a 'thing' by I-56 in many Japanese documents Sunk east of Leyte by and on 28 October 1944. 629 Yokosuka Naval Arsenal 29 September 1942 30 June 1943 8 June 1944 Damaged USS LST-695 on 24 October 1944.Damaged on 25 October 1944 (?). Conversion to a Kaiten mother ship began in early October 1943 and completed in November 1944. Sunk by , , , and aircraft from east of Okinawa at on 18 April 1945. 631 Yokosuka Naval Arsenal 26 December 1942 9 October 1943 7 September 1944 Sank SS Wild Hunter on 28 July 1945, possibly by KaitenSank on 30 July 1945Damaged on 12 August 1945 by Kaiten (?) Converted to a Kaiten mother ship before completion. Decommissioned on 30 November 1945, scuttled off the Gotō Islands on 1 April 1946 as part of Operation Road's End. Wreck found in 2017. 633 - 636 Cancelled in 1943 5101 - 5114

V22A Type Project number S49A. Eighteen boats were planned under the Kai-Maru 5 Programme (Boats 5115 - 5132). However, all boats were cancelled in late 1943, because the IJN concentrated on production of from 1945.

Boats in class Boat No. Boat Builder Laid down Launched Completed Fate 5115 - 5132 Cancelled in 1943

Characteristics Type Type-B (I-15) Type-B Mod. 1 (I-40) Type-B Mod. 2 (I-54) V22A 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. 1A Model 10 diesels2 shafts 2 × Kampon Mk. 22 Model 10 diesels2 shafts 2 × Kampon Mk. 2 Model 10 diesels2 shaftsPower Surfaced 12,400 bhp 11,000 bhp 4,700 bhp 11,000 bhp Submerged 2,000 shp 2,000 shp 1,200 shp 2,400 shpSpeed Surfaced Submerged Range Surfaced at at at at Submerged at at at at Test depth Fuel 774 tons 814 tons 842.8 tons 735 tons Complement 94 94 94 No data Armament (initial) • 6 × Torpedo tubes(6 × front)• 17 × Type 95 torpedoes• 1 × L/40 11th Year Type naval gunCampbell, John Naval Weapons of World War Two p.191• 2 × Type 96 25mm AA guns • 6 × TTs (6 × front)• 17 × Type 95 torpedoes• 1 × L/40 11th Year Type Naval gun• 2 × Type 96 25mm AA guns • 6 × TTs (6 × front)• 19 × Type 95 torpedoes• 1 × L/40 11th Year Type Naval gun• 2 × Type 96 25mm AA guns • 8 × TTs (8 × front)• 16 × torpedoes• 1 × 14 cm/40 11th Year Type naval gun• 4 × 25mm AA guns• 8 × naval mines Aircraft and facilities • Catapult and hangar• 1 × Watanabe E9W1 Slim seaplane • Catapult and hangar• 1 × Yokosuka E14Y2 Glen seaplane • Catapult and hangar• 1 × Yokosuka E14Y2 Glen seaplane • Catapult and hangar• 1 × floatplane

References

Notes

Bibliography

, History of Pacific War Vol.17 I-Gō Submarines, Gakken (Japan), January 1998, Rekishi Gunzō, History of Pacific War Vol.35 Kō-hyōteki and Kōryū, Gakken (Japan), April 2002, Rekishi Gunzō, History of Pacific War Vol.36 Kairyū and Kaiten, Gakken (Japan), May 2002, 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.31 Japanese Submarines I, Ushio Shobō (Japan), September 1979, Book code 68343-31