The was a class of transport submarines of the Imperial Japanese Army

Imperial Japanese Army

-Foundation:During the Meiji Restoration, the military forces loyal to the Emperor were samurai drawn primarily from the loyalist feudal domains of Satsuma and Chōshū...

 (IJA), serving during the Second World War. IJA planned to build over 400 boats, however only 38 boats were completed until the end of war. The IJA called them .

Construction

In 1943 the IJA decided to build a transport submarine for themselves, because the IJA was soundly beaten by in the Solomon Islands campaign

Solomon Islands campaign

The Solomon Islands campaign was a major campaign of the Pacific War of World War II. The campaign began with Japanese landings and occupation of several areas in the British Solomon Islands and Bougainville, in the Territory of New Guinea, during the first six months of 1942...

 and needed a way to supply the isolated garrisons on the Pacific islands.

Yu I type

The class consists of four subclasses by builders, however, they were unofficially. About their appearance, they were different in sail

Sail (submarine)

In naval parlance, the sail or fin of a submarine is the tower-like structure found on the dorsal surface of submarines...

.

Yu 1 class

Basic model of Yu I type. First boat (Yu-1) was prototype of the Yu I type boats. The Hitachi-Kasado Factory build all of the Yu 1-class boats. Their sail was shut tightly.

• Yu 1, laid down in February 1943, completed on 31 October 1943, lost in an accident at Lingayen Gulf
  Lingayen Gulf
  The Lingayen Gulf is an extension of the South China Sea on Luzon in the Philippines stretching . It is framed by the provinces of Pangasinan and La Union and sits between the Zambales Mountains and the Cordillera Central...
  
   on 2 January 1945.
• Yu 2, sunk by USS Pringle
  USS Pringle (DD-477)
  USS Pringle , a , was a ship of the United States Navy named for Vice Admiral Joel R. P. Pringle .Pringle was laid down by the Charleston Navy Yard, on 31 July 1941; launched on 2 May 1942, sponsored by Mrs. John D. H. Kane; and commissioned on 15 September 1942, with Lieutenant Commander Harold O...
  
  , Renshaw
  USS Renshaw (DD-499)
  USS Renshaw , a , was the third ship of the United States Navy of that name, in honor of Commander William B. Renshaw.Renshaw was laid down 7 May 1942 by the Federal Shipbuilding & Drydock Company in Kearny, New Jersey; launched on 13 October 1942, sponsored by Miss Dorothy Lillian Renshaw; and...
  
  , Waller
  USS Waller (DD-466)
  USS Waller , a Fletcher-class destroyer, was a ship of the United States Navy named for Major General Littleton Waller, USMC ....
  
   and Saufley
  USS Saufley (DD-465)
  USS Saufley , a Fletcher-class destroyer, was a ship of the United States Navy named for Lieutenant Richard Saufley....
  
   at Ormoc Bay
  Ormoc Bay
  Ormoc Bay is a bay on the island of Leyte in the Philippines. The bay is an inlet of the Camotes Sea. The city of Ormoc lies at the head of the bay and exports rice, copra and sugar. The World War II Battle of Ormoc Bay took place from November 11 until mid-December in Ormoc Bay during late 1944....
  
   on 27 November 1944.
• Yu 3, lost in an accident at Lingayen Gulf in January 1945, salvaged by USS Grasp
  USS Grasp (ARS-24)
  USS Grasp was a Diver-class rescue and salvage ship commissioned by the U.S. Navy during World War II. Her task was to come to the aid of stricken vessels....
  
   on 18 January 1945, carried out by USS Rushmore
  USS Rushmore (LSD-14)
  USS Rushmore was a Casa Grande-class dock landing ship of the United States Navy.She was the named in honor of Mount Rushmore National Memorial in the Black Hills of South Dakota....
  
   in May 1945.
• Yu 4, survived war.
• Yu 5, survived war.
• Yu 6, assigned Detachment 2, Transport Sunbmarine Group on 13 February 1945, survived war.
• Yu 7, assigned Detachment 2, Transport Sunbmarine Group in November 1944, survived war.
• Yu 8, survived war.
• Yu 9, survived war.
• Yu 10, assigned Detachment Kuchinotsu
  Kuchinotsu, Nagasaki
  was a town located in Minamitakaki District, Nagasaki, Japan.On March 31, 2006 Kuchinotsu was merged with the towns of Arie, Fukae, Futsu, Kazusa, Kitaarima, Minamiarima and Nishiarie, all from Minamitakaki District, to form the new city of Minamishimabara....
  
  , Transport Sunbmarine Group on 15 May 1945, survived war.
• Yu 11, assigned Detachment Kuchinotsu, Transport Sunbmarine Group on 15 May 1945, assigned Detachment Mikuriya
  Matsuura, Nagasaki
  is a city located in Nagasaki, Japan. Matsuura City is bordered on three sides by mountains. Matsuura Bay makes up the fourth side.-History:Mention of a "Matsuura County" appears in written records from the Heian period, and this area was the home of the Matsuura clan, a local warrior clan...
  
   in June 1945, survived war.
• Yu 12, assigned Detachment Kuchinotsu, Transport Sunbmarine Group on 15 May 1945, survived war.
• Yu 13, assigned assigned Detachment Mikuriya in June 1945, survived war.
• Yu 14, assigned Detachment Kuchinotsu, Transport Sunbmarine Group on 15 May 1945, assigned Detachment Mikuriya in June 1945, survived war.
• Yu 16, survived war.
• Yu 17, survived war.
• Yu 18, survived war.
• Yu 19, survived war.
• Yu 20, survived war.
• Yu 21, survived war.
• Yu 22, survived war.
• Yu 23, survived war.
• Yu 24, survived war.
• Yu 25, incomplete until the end of the war.

Yu 1001 class

The Japan Steel Works-Kaita Factory build all of the Yu 1001-class boats. They equipped open-top sail.

• Yu 1001, assigned Detachment 2, Transport Sunbmarine Group in November 1944, sunk by air raid at Shimoda
  Shimoda, Shizuoka
  is a city and port in Shizuoka, Japan.As of 2010, the city had an estimated population of 25,054 and a population density of 242 persons per square kilometer...
  
   on 12 August 1945.
• Yu 1002, assigned Detachment 2, Transport Sunbmarine Group on 11 February 1945, survived war.
• Yu 1003, assigned Detachment 2, Transport Sunbmarine Group on 11 February 1945, survived war.
• Yu 1005, assigned Detachment 2, Transport Sunbmarine Group on 13 February 1945, survived war.
• Yu 1006, survived war.
• Yu 1007, assigned Detachment Kuchinotsu, Transport Sunbmarine Group on 15 May 1945, assigned Detachment Mikuriya in June 1945, survived war.
• Yu 1008, survived war.
• Yu 1009, survived war.
• Yu 1010, survived war.
• Yu 1011, incomplete until the end of the war.
• Yu 1012, incomplete until the end of the war.
• Yu 1013, incomplete until the end of the war.
• Yu 1014, incomplete until the end of the war.

Yu 2001 class

The Andō Iron Works-Tsukishima Factory build all of the Yu 2001-class boats. First boat (Yu-2001) was second prototype of the Yu I type boats. They fitted deck house root of the sail for improve comfort by builder's consideration.

• Yu 2001, survived war.
• Yu 2002, survived war.
• Yu 2003, incomplete until the end of the war.
• Yu 2004, incomplete until the end of the war.
• Yu 2005, incomplete until the end of the war.
• Yu 2006, incomplete until the end of the war.

Yu 3001 class

The Chōsen Machinery-Jinsen Factory build all of the Yu 3001-class boats.

• Yu 3001, survived war.
• Yu 3002, sunk by rough weather in 1945.
• Yu 3003, survived war.
• Yu 3005, incomplete until the end of the war.
• Yu 3006, incomplete until the end of the war.
• Yu 3007, incomplete until the end of the war.
• Yu 3008, incomplete until the end of the war.
• Yu 3009, incomplete until the end of the war.
• Yu 3010, incomplete until the end of the war.

Yu II type

Improved model of the Yu I type. Yu II was built by Kampon technical guidance. The IJN used the Ha-101-class submarine

Ha-101 class submarine

The was a transport submarine of the Imperial Japanese Navy , serving during late World War II. The IJN planned to build 12 boats, but only 10 vessels were completed by the end of the war. The IJN called these submarines . Several boats were converted to tankers or mother ships for the midget...

 drawings and designed this.

• Ushio, prototype of the Yu II type, laid down in August 1944, launched on 16 May 1945, completed on 18 August 1945.