The I-200-class 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 Senkou
(Japanese: 潜高, from Sen
, abbreviation of 潜水艦, Sensuikan
, "Submarine", and kou
, abbreviation of 高速, Kousoku
, "High speed"). They were the fastest operational submarines built during World War II, surpassing even the German Type XXI 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 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 . She could attain a submerged speed of over , making her the fastest submarine of her day. The results gained from experiments with Number 71 formed the basis for the I-200 class submarines.
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
, 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" (Sentaka) 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 which was reduced to for practical reasons.
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 centre of gravity and improve dynamic stability
- Give the pressure hull and casing a highly streamlined form
- Make the conning tower as small as possible
- Abandon fixed deck guns, which were housed in closable recesses
- Use steel plates for the upper deck rather than wood
- Install underwater charging system (Shnorkel)
- Fit large horizontal fins at the stern
The I-200 class bore little resemblance to earlier I-boats, which were optimized for long range and high surfaced speed. By contrast, the I-200 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 was double that of contemporary American designs. The I-200 class was also equipped with a crude snorkel, allowing underwater diesel operation while recharging batteries.
The I-200 displaced 1,291 tons surfaced and 1,451 tons submerged. It had a test depth of . Armament consisted of four 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
, 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
, which were sailed to Hawaii
by US Navy
technicians for further inspection.
On March 26, 1946, the US Navy decided to scuttle all captured Japanese submarines. On 5 April, 1946, I-202 was scuttled in Japanese waters. On May 21, 1946, I-203 was torpedoed and sunk by submarine off the Hawaiian Islands. On May 23, 1946, I-201 was torpedoed and sunk by .
- I-201, captured and sunk by USS Queenfish (SS-393), May 23, 1946
- I-202, captured and scuttled by USN off Goto Island, 5 April, 1946
- I-203, captured and sunk by USS Caiman (SS-323), May 21, 1946
- I-204, sunk by air raid at Kure, 22 June 1945, salvaged and scrapped at Kure Feb-May 1948
- I-205, sunk by air raid July 28 1945, salvaged and scrapped at Kure May-August 1948
- I-206, scrapped at Kure October-November 1946
- I-207, construction halted 17 April 1945, 20% complete,
- I-208, construction halted 17 April 1945, 20% complete; scrapped at Kure April-May 1946 with I-207
A refurbished I-203
is used by the characters in the film Hell and High Water
- Lengerer, Hans "The High-Speed Submarines of the I 201 Class". Warship 2006 28 pp. 59-77.
- Stille, Mark; Tony Bryan Imperial Japanese Navy Submarines 1941-45. Osprey Publishing.