View source for I-201-class submarine

{{Short description|Class of submarines of the Imperial Japanese Navy}}
{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=[[File:SenTaka.jpg|300px|Senkou I-202]]
|Ship caption=Sentaka ''I-202'' at high surface speed
}}
{{Infobox ship class overview
|Name=
|Builders=[[Kure Naval Arsenal]]
|Operators={{navy|Empire of Japan}}
|Class before={{sclass|I-400|submarine|1}}
|Class after=
|Subclasses=*''I-201''-class, Project No. S56<sub>3</sub>
*''I-207''-class, Project No. S56B
|Cost=
|Built range=1945
|In service range=1945
|In commission range=1945
|Total ships planned=23
|Total ships completed=3
|Total ships scrapped=3
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=
|Ship type=[[Submarine]]
|Ship displacement=*{{convert|1291|LT|abbr=on}} surfaced
*{{convert|1450|LT|abbr=on}} submerged
|Ship length=*{{convert|79|m|abbr=on}} overall
*{{convert|59.2|m|abbr=on}} pressure hull
|Ship beam=*{{convert|5.8|m|abbr=on}} pressure hull
*{{convert|9.2|m|abbr=on}} max. across stern fins
|Ship height= {{convert|7|m|abbr=on}} (keel to main deck)
|Ship propulsion=*[[Diesel-electric]]
*2 × [[MAN Diesel|MAN]] Mk.1 diesel (マ式1号ディーゼル, Ma-Shiki 1 Gō diesel), build by [[Kawasaki Heavy Industries|Kawasaki]] and [[Mitsubishi Heavy Industries|Mitsubishi]]. {{convert|2750|hp|abbr=on}}
*4 × electric motors, {{convert|5000|hp|abbr=on}} at 600 rpm
*2 shafts
|Ship speed=*{{convert|15.75|kn|km/h|lk=in}} surfaced
*{{convert|19|kn|km/h}} submerged
|Ship range=*{{convert|15000|nmi|km|abbr=on|lk=in}} at {{convert|6|kn|km/h}}
*{{convert|7800|nmi|km|abbr=on|lk=in}} at {{convert|11|kn|km/h}}
*{{convert|5800|nmi|km|abbr=on|lk=in}} at {{convert|14|kn|km/h}}
*Submerged: {{convert|135|nmi|km|abbr=on|lk=in}} at {{convert|3|kn|km/h}}
|Ship test depth={{convert|110|m|ft|abbr=on}}
|Ship complement=*31 (plan)
*approx. 50 (actual)
|Ship armament=*4 × {{convert|533|mm|in|0|abbr=on}} bow [[torpedo]] tubes
*10 × [[Type 95 torpedo]]es
*2 × [[Type 96 25 mm AT/AA Gun|Type 96 25 mm AA gun]]s
|Ship notes=
}}
|}
[[File:Japanese I-201-class submarine Kure area October 1945.PNG|thumb|An unidentified ''I-201''-class submarine in the vicinity of [[Kure, Hiroshima|Kure]], [[Japan]], in October 1945.]]
The {{nihongo|'''''I-201''-class submarines'''|伊二百一型潜水艦|I-ni-hyaku-ichi-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 {{nihongo|'''''Sentaka-Dai type submarine'''''|潜高大型潜水艦|Sen-Taka-Dai-gata sensuikan, "Submarine High speed-Large type"}} or {{nihongo|'''''Sentaka type submarine'''''|潜高型潜水艦|''Sen-Taka-gata sensuikan'', "Submarine High speed type"}}. The type name, was shortened to {{nihongo|Suichū '''Kō'''soku '''Sen'''suikan '''Ō'''-gata|水中'''高'''速'''潜'''水艦'''大'''型|Underwater High speed Submarine Large type}}.<ref>The {{nihongo2|潜高大|}} read as "Sentaka-Dai", but the {{nihongo2|高速|}} read as "Kō-soku" and {{nihongo2|大型|}} read as "Ō-gata" in Japanese.</ref>

They were one of the fastest submarine class built during World War II, second only to [[German Type XVII submarine|Walter Type XVII]] closed-cycle powered submarines. Twenty-three units were ordered from the [[Kure Naval Arsenal]] 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.

==Background==
In 1938 the Imperial Japanese Navy constructed an experimental high-speed submarine for evaluation purposes, which was designated {{nihongo|[[Submarine No.71|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 {{convert|140|ft|abbr=on}}. She could attain a submerged speed of over {{convert|21|kn|abbr=on}}, 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.<ref name=stille38>Stille, p. 38</ref>

==Design==
[[File:I-201 class general arrangement sections.svg|thumb|300px|left|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 [[Anti-submarine warfare|ASW]] techniques coming into service, such as [[radar]], [[Huff-Duff|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&ndash;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 {{convert|25|kn|abbr=on}} which was reduced to {{convert|20|kn|abbr=on}} for practical reasons. Nevertheless, they were the fastest operational submarines of World War II, outpacing even the German [[German Type XXI submarine|Type XXI]].<ref>Stille, Mark. ''Imperial Japanese Navy Submarines 1941-45'' (Osprey, 2007), p.38.</ref>

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 ([[Submarine snorkel|snorkel]])
*Fit large horizontal control surfaces at the stern instead of the more usual bow-mounted dive planes; this improved directional stability and may have decreased turbulence-induced drag.<ref>Lengerer, p. 62</ref>
*Reduce the crew and crew accommodation to provide battery space; the ''Sen-Taka'' was designed for a crew of 31, compared to that the similar-sized [[Ro-35-class submarine|''Sen-Chu'']] (54), and the [[I-51-class submarine|''Kai Dai 1'']] (60) Types (in practice the ''SenTaka'' needed a crew of 50 when it became operational, leading to an unforeseen habitation problem).
*Restrict the armament, also to save space; the ''Sen-Taka'' had the same torpedo outfit as the smaller ''Sen-Chu'' 2nd class submarine, and just half that of the comparable ''Kaidai'' 1st class submarine. Also the ''Sen-Taka'' had no deck gun, and the AA armament carried had to be held in retractable mounts, requiring hull space, in order to meet the streamlining requirement.

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 {{convert|19|kn|km/h|0}} was double that of contemporary American designs. The ''I-201''s, like other Japanese submarines of the period,<ref>Stille, p.35 & ''passim''.</ref> were also equipped with a crude [[submarine snorkel|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 {{convert|360|ft|m|0}}. Armament consisted of four 53&nbsp;cm (21&nbsp;in) [[torpedo tube]]s and 10 [[Type 95 torpedo|Type 95]] [[torpedo]]es. The two 25&nbsp;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.

==Fate==
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 {{sclass|I-400|submarine|5}} 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. 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|SS-323|6}} off the Hawaiian Islands. On 23 May 1946, ''I-201'' was torpedoed and sunk by {{USS|Queenfish|SS-393|6}}.  The [[Hawaii Undersea Research Laboratory]] found the wreck of the ''I-201'' near Hawaii using submersible craft in 2009.<ref>{{cite web | url = https://www.nytimes.com/2009/11/13/science/13wreck.html?_r=1 | title = 2 Sunken Japanese Subs Are Found Off Hawaii | date = November 14, 2009 | access-date = November 14, 2009 | work = New York Times | author = Henry Fountain }}</ref>
{{Clear}}

==Boats in class==
{| class="wikitable"
|| '''Sub class''' || '''Boat #''' || '''Boat''' || '''Builder''' || '''Laid down''' || '''Launched''' || '''Completed''' || '''Decommissioned''' || '''Fate'''
|-
| rowspan="6"|''I-201''<br>(Pr. S56<sub>3</sub>) || 4501 || {{ship|Japanese submarine|I-201||2}}<ref>{{nihongo|伊号第201潜水艦|I-Gō Dai-201 Sensuikan}}. The same shall apply hereinafter.</ref> || rowspan="8" | [[Kure Naval Arsenal]] || 1 March 1944 || 22 July 1944 || 2 February 1945 || 30 November 1945 || Sunk as a target off the Hawaiian Islands by {{ship|USS|Queenfish|SS-393|6}} on 23 May 1946
|-
| 4502 || {{ship|Japanese submarine|I-202||2}} || 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 || {{ship|Japanese submarine|I-203||2}} || 1 June 1944 || 20 September 1944 || 29 May 1945 || 30 November 1945 || Sunk as a target off the Hawaiian Islands by {{ship|USS|Caiman|SS-323|6}} on 21 May 1946
|-
| 4504 || ''I-204'' || 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'' || 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'' || 27 October 1944 || 26 March 1945 || || || 85% complete, construction stopped on 26 March 1945, scrapped at Kure October 1946-January 1947
|-
| rowspan="3"|''I-207''<br>(Pr. S56B) || 4507 || ''I-207'' || 27 December 1944 || || || || 20% complete, construction stopped on 17 April 1945, scrapped at Kure April–May 1946
|-
| 4508 || ''I-208'' || 17 February 1945 || || || || 5% complete, construction stopped on 17 April 1945, scrapped at Kure April–May 1946 with I-207<ref>Lengerer, p. 75</ref>
|-
| 4509-4523 || || || || || || || Constructions were not started until the end of the war.
|}

==Influences==
The I-201 design and technology influenced [[Japanese Maritime Self Defense Force]] {{ship|JDS|Oyashio||6}} (1959).

==In fiction==
A refurbished ''I-203'' is used by the characters in the film ''[[Hell and High Water (1954 film)|Hell and High Water]]'' (1954).

==See also==
*[[German Type XXI submarine]]
*[[Ha-201-class submarine]]
*[[Submarine No.71|Vessel Number 71]]
*{{ship|JDS|Oyashio|SS-511|}}

==Notes==
{{reflist}}

==References==
*{{cite journal | last = Lengerer | first = Hans | title = The High-Speed Submarines of the I 201 Class | journal = Warship | volume = 28 | pages =59–77 | publisher = Chrysalis Books | year = 2006 }}
*{{cite book | last = Stille | first = Mark |author2=Tony Bryan | title = Imperial Japanese Navy Submarines 1941-45 | publisher = Osprey Publishing | year = 2007 | isbn = 978-1-84603-090-1}}
*Stille, Mark. ''Imperial Japanese Navy Submarines 1941-45''. Osprey, 2007.
*''{{cite web |url=http://rekigun.net/ |title=''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==
*[https://web.archive.org/web/20051027100212/http://pacerfarm.org/i-400/ The Transpacific voyage of the I-400]
*[http://www.combinedfleet.com/ss.htm Submarines of the Imperial Japanese Navy]

{{I-201 class submarine}}
{{WWII Japanese ships}}

[[Category:Submarine classes]]
[[Category:I-201-class submarines| ]]<!-- please leave space for proper cat sorting -->
[[Category:Submarines of the Imperial Japanese Navy]]