Military Wiki
I-201-class submarine
Senkou I-202
Sentaka I-202 at high surface speed
Class overview
Builders: Kure Navy Yard
Operators:  Imperial Japanese Navy
Preceded by: I-400 class submarine
Subclasses:I-201-class, Project No. S563
I-207-class, Project No. S56B
Built: 1945
In service: 1945
In commission: 1945
Planned: 23
Completed: 3
Retired: 3
General characteristics
Type: Submarine
Displacement: 1,290 t (1,270 long tons; 1,420 short tons) surfaced
1,503 t (1,479 long tons; 1,657 short tons) submerged
Length: 79 m (259 ft) overall
59.2 m (194 ft) pressure hull
Beam: 5.8 m (19 ft) pressure hull
9.2 m (30 ft) max. across stern fins
Height: 7 m (23 ft) (keel to main deck)
Propulsion: Diesel-electric
2 × MAN Mk.1 diesel (マ式1号ディーゼル, Ma-Shiki 1 Gō diesel), build by Kawasaki and Mitsubishi. 2,750 hp (2,050 kW)
4 × electric motors, 5,000 hp (3,700 kW) at 600 rpm
2 shafts
Speed: 15.75 knots (29.17 km/h) surfaced
19 knots (35 km/h) submerged
Range: 15,000 nmi (28,000 km) at 6 knots (11 km/h)
7,800 nmi (14,400 km) at 11 knots (20 km/h)
5,800 nmi (10,700 km) at 14 knots (26 km/h)
Submerged: 135 nmi (250 km) at 3 knots (5.6 km/h)
Test depth: 110 m (360 ft)
Complement: 31 (plan)
approx. 50 (actual)
Armament: • 4 × 533 mm (21 in) bow torpedo tubes
• 10 × Type 95 torpedoes
• 2 × Type 96 25 mm AA guns

The I-201-class submarines (伊二百一型潜水艦 I-Nihyakuichi-gata sensuikan?) were submarines of the Imperial Japanese Navy during World War II. These submarines were of advanced design, built for high underwater speed, and were known as Submarine High speed-Large type (潜高大型 Sen Taka-Dai gata?) or Submarine-High speed type (潜高型 Sen Taka gata?). They were one of the fastest submarine class built during World War II, second only to Walter Type XVII closed-cycle powered submarines.

Twenty-three units were ordered from the Kure Navy Yard under the 1943 construction program. Due to the deteriorating war situation, only eight boats were laid down, and only three, numbered I-201, I-202 and I-203, were completed before the end of the war. None of them saw operational use.


In 1938 the Imperial Japanese Navy constructed an experimental high-speed submarine for evaluation purposes, which was designated Vessel Number 71 (第71号艦) for security purposes. Based on previous experience with high-speed, short-range midget submarines, Number 71 displaced only 230 tons surfaced with a length of 140 ft (43 m). She could attain a submerged speed of over 21 kn (39 km/h; 24 mph), making her the fastest submarine of her day. The results gained from experiments with Number 71 formed the basis for the I-201 class submarines.[1]


General arrangements and sections of the type I-201 class submarine.

By late 1942 it had become apparent to the IJN that conventional submarines were unable to survive the new ASW techniques coming into service, such as radar, HF/DF, sonar, and new depth charge projectors. New submarines were required, with a higher underwater than surface speed, quick-diving capability, quiet underwater running, and a high underwater operational radius.

The IJN General Staff made an official request for high-speed submarines in October 1943 and among the ships planned in 1944 to be constructed in 1945 were 23 "underwater high speed submarines" (Sen taka) temporarily designated "Ships No. 4501–4523".

The General Staff's final requirements were stated in Order No. 295 dated 29 October 1943 to the Navy Technical Department. These included an underwater speed of 25 kn (46 km/h; 29 mph) which was reduced to 20 kn (37 km/h; 23 mph) for practical reasons. Nevertheless, they were the fastest operational submarines of World War II, outpacing even the German Type XXI.[2]

To meet the requirement for high underwater speed the designers had to:

  • Adopt a single-hull structure
  • Locate the main ballast tank higher than previous submarines to give a higher center of gravity and improve dynamic stability
  • Give the pressure hull and casing a highly streamlined form
  • Make the conning tower as small as possible
  • Replace fixed deck guns with retractable mounts housed in shuttered recesses when submerged.
  • Use steel plates for the upper deck rather than wood
  • Install underwater charging system (snorkel)
  • Large horizontal control surfaces were fitted at the stern instead of the more usual bow-mounted dive planes; this improved directional stability and may have decreased turbulence-induced drag.[3]

The I-201 class bore little resemblance to earlier I-boats, which were optimized for long range and high surfaced speed. By contrast, the I-201 emphasized submerged performance. It featured powerful electric motors, streamlined all-welded hulls, and a large capacity battery consisting of 4,192 cells. The maximum underwater speed of 19 knots (35 km/h) was double that of contemporary American designs. The I-201s, like other Japanese submarines of the period,[4] were also equipped with a crude snorkel, allowing underwater diesel operation while recharging batteries.

I-201 displaced 1,291 tons surfaced and 1,451 tons submerged. It had a test depth of 360 feet (110 m). Armament consisted of four 21 in (53 cm) torpedo tubes and 10 Type 95 torpedoes. The two 25 mm anti-aircraft guns were housed in retractable mounts to maintain streamlining. The submarine was designed for mass production, with large sections prefabricated in factories and transported to the slip for final assembly.


Two submarines, I-201 and I-203, were seized and inspected by the US Navy at the end of the hostilities. They were part of a group of four captured submarines, including the giant I-400 and I-401, which were sailed to Hawaii by US Navy technicians for further inspection.

On 26 March 1946, the US Navy decided to scuttle these captured Japanese submarines to prevent the technology from falling into the hands of the Soviet Union at the beginning of the Cold War. On 5 April 1946, I-202 was scuttled in Japanese waters. On 21 May 1946, I-203 was torpedoed and sunk by submarine USS Caiman off the Hawaiian Islands. On 23 May 1946, I-201 was torpedoed and sunk by USS Queenfish. The Hawaii Undersea Research Laboratory found the wreck of the I-201 near Hawaii using submersible craft in 2009.[5]

Boats in class

Sub class Boat # Boat Builder Laid down Launched Completed Decommissioned Fate
(Pr. S563)
4501 I-201 Kure Naval Arsenal 1 March 1944 22 July 1944 2 February 1945 30 November 1945 Sunk as a target off the Hawaiian Islands by USS Queenfish on 23 May 1946
4502 I-202 Kure Naval Arsenal 1 May 1944 2 September 1944 12 February 1945 30 November 1945 Scuttled by U.S. Navy off Gotō Islands on 5 April 1946
4503 I-203 Kure Naval Arsenal 1 June 1944 20 September 1944 29 May 1945 30 November 1945 Sunk as a target off the Hawaiian Islands by USS Caiman on 21 May 1946
4504 I-204 Kure Naval Arsenal 1 August 1944 16 December 1944 90% complete, sunk by air raid on 22 June 1945, salvaged and scrapped at Kure February–May 1948
4505 I-205 Kure Naval Arsenal 4 September 1944 15 February 1945 80% complete, sunk by air raid on 28 July 1945, salvaged and scrapped at Kure May–August 1948
4506 I-206 Kure Naval Arsenal 27 October 1944 26 March 1945 85% complete, construction stopped on 26 March 1945, scrapped at Kure October 1946-January 1947
(Pr. S56B)
4507 I-207 Kure Naval Arsenal 27 December 1944 20% complete, construction stopped on 17 April 1945, scrapped at Kure April–May 1946
4508 I-208 Kure Naval Arsenal 17 February 1945 5% complete, construction stopped on 17 April 1945, scrapped at Kure April–May 1946 with I-207[6]
4509-4523 Constructions were not started until the end of the war.


The I-201 design and technology influenced Japanese Maritime Self Defense Force Oyashio (1959, SS-511).

In fiction

A refurbished I-203 is used by the characters in the film Hell and High Water (1954).

See also


  1. Stille, p. 38
  2. Stille, Mark. Imperial Japanese Navy Submarines 1941-45 (Osprey, 2007), p.38.
  3. Lengerer, p. 62
  4. Stille, p.35 & passim.
  5. Henry Fountain (November 14, 2009). "2 Sunken Japanese Subs Are Found Off Hawaii". New York Times. Retrieved November 14, 2009. 
  6. Lengerer, p. 75


  • Lengerer, Hans (2006). "The High-Speed Submarines of the I 201 Class". Chrysalis Books. pp. pp. 59–77. 
  • Stille, Mark; Tony Bryan (2007). Imperial Japanese Navy Submarines 1941-45. Osprey Publishing. ISBN 1-84603-090-0. 
  • Stille, Mark. Imperial Japanese Navy Submarines 1941-45. Osprey, 2007.
  • "Rekishi Gunzō". , History of Pacific War Vol.17 I-Gō Submarines, Gakken (Japanese publishing company), January 1998, ISBN 4-05-601767-0
  • The Maru Special, Japanese Naval Vessels No.132, Japanese submarines I, Ushio Shobō (Japanese publishing company), February 1988

External links

This page uses Creative Commons Licensed content from Wikipedia (view authors).