Type 3 submergence transport vehicle

Yu 1 in Hitachi Ltd., Kasado Factory (1943)
Class overview
Name:	Type 3 submergence transport vehicle
Builders:	Hitachi Ltd. Japan Steel Works Andō Iron Works Chōsen Machinery
Operators:	Imperial Japanese Army
Subclasses:	Yu I type Yu 1 (Hitachi Ltd.) Yu 1001 (Japan Steel Works) Yu 2001 (Andō Iron Works) Yu 3001 (Chōsen Machinery) Yu II type Ushio (Prototype, Hitachi Ltd.)
Built:	1943–45
In commission:	1943–45
Planned:	400 and more
Completed:	38
Lost:	5
Scrapped:	34
General characteristics Yu I type
Type:	Transport submarine
Displacement:	274 long tons (278 t) surfaced 346 long tons (352 t) submerged
Length:	41.40 m (135 ft 10 in) overall
Beam:	3.90 m (12 ft 10 in)
Draft:	3.00 m (9 ft 10 in)
Propulsion:	2 × Hesselman engines 400 bhp surfaced 75 shp submerged single shaft
Speed:	10 knots (19 km/h) surfaced 4 knots (7.4 km/h) submerged
Range:	1,500 nmi (2,800 km) at 8 knots (15 km/h) surfaced 32 nmi (59 km) at 4 knots (7.4 km/h) submerged
Test depth:	100 m (330 ft)
Capacity:	24 tons freight or 40 troops
Complement:	23
Armament:	Yu 1, Yu 2 and Yu 3 1 × Type 4 37 mm shipboard gun 5 × Type 99 light machine guns Yu 1001 1 × Type 4 37 mm shipboard gun 2 × IJN Type 92 13 mm AA guns Yu 2001 1 × Type 4 37 mm shipboard gun
General characteristics Yu II type [1]
Type:	Transport submarine
Displacement:	430 long tons (437 t) surfaced 540 long tons (549 t) submerged
Length:	55.00 m (180 ft 5 in) overall
Beam:	7.00 m (23 ft 0 in)
Draft:	3.13 m (10 ft 3 in)
Propulsion:	2 × intermediate diesels 700 bhp surfaced, 2 shafts
Speed:	14.5 knots (26.9 km/h; 16.7 mph) surfaced 4.5 knots (8.3 km/h; 5.2 mph) submerged
Test depth:	150 m (492 ft 2 in)
Capacity:	40 tons freight
Armament:	1 × Type 1 47 mm AT gun 5 × Type 98 20 mm AA guns

The Type 3 submergence transport vehicle (三式潜航輸送艇 San-Shiki Senkō Yusōtei) was a class of transport submarines built for the Imperial Japanese Army (IJA) during the Second World War. The IJA planned to build over 400 boats, however only 38 boats were completed until the end of war. The IJA called them Maru Yu (マルゆ).

Construction

In 1943 the IJA decided to build a transport submarine for themselves, because the IJA was soundly beaten in the Solomon Islands campaign and needed a way to supply the isolated garrisons on the Pacific islands.

Boats in classes

Yu I type

The class consists of four unofficial subclasses resulting from manufacturing differences among the contracted builders. The manufacturer may be discerned by the appearance of the sail.

Yu 1-class

Yu 1 in trial at Kudamatsu (1944)

Yu 3 docking to USS Rushmore (1945)

Basic model of Yu I type. First boat Yu 1 was prototype of the Yu I type boats. The Hitachi-Kasado Factory built all of the Yu 1-class boats. Their sail was closed.

• Yu 1, laid down in February 1943, completed on 31 October 1943, lost in an accident at Lingayen Gulf on 2 January 1945.
• Yu 2, sunk by USS Pringle, Renshaw, Waller and Saufley at Ormoc Bay on 27 November 1944.
• Yu 3, lost in an accident at Lingayen Gulf in January 1945, salvaged by USS Grasp on 18 January 1945, carried out by USS Rushmore in May 1945.
• Yu 4, survived war.
• Yu 5, survived war.
• Yu 6, assigned Detachment 2, Transport Submarine Group on 13 February 1945, survived war.
• Yu 7, assigned Detachment 2, Transport Submarine Group in November 1944, survived war.
• Yu 8, survived war.
• Yu 9, survived war.
• Yu 10, assigned Detachment Kuchinotsu, Transport Submarine Group on 15 May 1945, survived war.
• Yu 11, assigned Detachment Kuchinotsu, Transport Submarine Group on 15 May 1945, assigned Detachment Mikuriya in June 1945, survived war.
• Yu 12, assigned Detachment Kuchinotsu, Transport Submarine Group on 15 May 1945, survived war.
• Yu 13, assigned Detachment Mikuriya in June 1945, survived war.
• Yu 14, assigned Detachment Kuchinotsu, Transport Submarine 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

Yu 1001 class at Tateyama (1945)

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

• Yu 1001, launched on 27 March 1944, completed on 15 June 1944, assigned Detachment 2, Transport Submarine Group in November 1944, sunk by air raid at Shimoda on 12 August 1945.
• Yu 1002, assigned Detachment 2, Transport Submarine Group on 11 February 1945, survived war.
• Yu 1003, assigned Detachment 2, Transport Submarine Group on 11 February 1945, survived war.
• Yu 1005, assigned Detachment 2, Transport Submarine Group on 13 February 1945, survived war.
• Yu 1006, survived war.
• Yu 1007, assigned Detachment Kuchinotsu, Transport Submarine 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

Yu 2001 trial-run in Tōkyō Bay (1944)

The Andō Iron Works-Tsukishima Factory build all of the Yu 2001-class boats. First boat (Yu-2001) was the second prototype of the Yu I type boats. They fitted a deck house root to the sail for improved crew comfort.

• Yu 2001, launched on 12 February 1944, survived war.
• Yu 2002, launched on 31 March 1945, 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, launched on 10 April 1944, completed on 2 August 1944, 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 drawings and designed this.

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

Footnotes

1. Atsumi Nakashima, p.130

See also

• Type D submarine
• Ha-101-class submarine
• German submarine Deutschland
• Type 4 Ka-Tsu
• Imperial Japanese Army Railways and Shipping Section

Bibliography

• Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-962-6.
• Carpenter, Dorr B. & Polmar, Norman (1986). Submarines of the Imperial Japanese Navy 1904–1945. London: Conway Maritime Press. ISBN 0-85177-396-6.
• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Rekishi Gunzō, History of Pacific War Extra, Perfect guide, The submarines of the Imperial Japanese Forces, Gakken, Tokyo Japan, 2005, ISBN 4-05-603890-2.
• Rekishi Gunzō, History of Pacific War Vol.45, Truth histories of the Imperial Japanese Naval Vessels, Gakken, Tokyo Japan, 2004, ISBN 4-05-603412-5.
• Ships of the World No.506, Kaijinsha, Tokyo Japan, 1996.
• The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III, Ushio Shobō, Tokyo Japan, 1980.
• Atsumi Nakashima, Army Submarine Fleet, "The secret project !, The men challenged the deep sea", Shinjinbutsu Ōraisha, Tokyo Japan, 2006, ISBN 4-404-03413-X.
• 50 year history of the Japan Steel Works (first volume and second volume), Japan Steel Works, 1968.