Ha-101-class submarine

(left to right) Ibuki, Ha-105, Ha-106 and Ha-109
Class overview
Name	Ha-101-class submarine
Builders	Kawasaki Shipbuilding Mitsubishi Heavy Industries
Operators	Imperial Japanese Navy
Cost	2,135,000 JPY[1]
Built	1944–45
In commission	1944–45
Planned	12
Completed	10
Scrapped	10
General characteristics
Type	Transport submarine
Displacement	436 t (429 long tons) surfaced 501 t (493 long tons) submerged
Length	44.5 m (146 ft 0 in)
Beam	6.1 m (20 ft 0 in)
Draft	4.04 m (13 ft 3 in)
Installed power	400 bhp (300 kW) (diesels) 150 hp (110 kW) (electric motor)
Propulsion	Diesel-electric 1 × diesel engines 1 × electric motor
Speed	10 knots (19 km/h; 12 mph) surfaced 5 knots (9.3 km/h; 5.8 mph) submerged
Range	3,000 nmi (5,600 km; 3,500 mi) at 10 knots (19 km/h; 12 mph) surfaced 46 nmi (85 km; 53 mi) at 2.3 knots (4.3 km/h; 2.6 mph) submerged
Test depth	100 meters (328 ft)
Capacity	60 metric tons (59 long tons)
Complement	22
Armament	1 × single 25 mm (1 in) Type 96 anti-aircraft gun

The Ha-101-class submarine (波百一型潜水艦, Ha-hyaku-ichi-gata Sensuikan) was a transport submarine built for the Imperial Japanese Navy (IJN) during 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 Sen'yu-Shō type submarine (潜輸小型潜水艦, Sen-Yu-Ko-gata sensuikan). The type name was shortened to Yusō Sensuikan Ko-gata (輸送潜水艦小型, Transport Submarine-Small Type).^[2]

Several boats were converted to tankers or mother ships for Kō-hyōteki model D "Kōryū" (甲標的丁型 蛟龍) midget submarines.

The Ha-101-class submarines were designed as small, cheap transport submarines to resupply isolated island garrisons. They displaced 436 metric tons (429 long tons) surfaced and 501 metric tons (493 long tons) submerged. The submarines were 44.5 meters (146 ft 0 in) long, had a beam of 6.1 meters (20 ft 0 in) and a draft of 4.04 meters (13 ft 3 in). They were designed to carry 60 metric tons (59 long tons) of cargo.^[3]

For surface running, the boats were powered by a single 400-brake-horsepower (298 kW) diesel engine that drove one propeller shaft. When submerged the propeller was driven by a 140-horsepower (104 kW) electric motor. They could reach 10 knots (19 km/h; 12 mph) on the surface and 5 knots (9.3 km/h; 5.8 mph) underwater.^[4] On the surface, the Ha-101s had a range of 3,000 nautical miles (5,600 km; 3,500 mi) at 10 knots (19 km/h; 12 mph); submerged, they had a range of 46 nmi (85 km; 53 mi) at 2.3 knots (4.3 km/h; 2.6 mph). The boats were armed a single mount for a 25 mm (1 in) Type 96 anti-aircraft gun.^[5]

Project number S57. In February 1944, the IJN planned a small-size transport submarine, the IJA planned the Maru Yu.

• Type 4 Ka-Tsu
• Imperial Japanese Army Railways and Shipping Section
• Type 3 submergence transport vehicle, Yu II type

• 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 (Japan), March 2005, ISBN 4-05-603890-2
• Ships of the World special issue Vol.37, History of Japanese Submarines, "Kaijinsha"., (Japan), August 1993
• The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III, Ushio Shobō (Japan), September 1980, Book code 68343-43
• The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition", Ushio Shobō (Japan), February 1988, Book code 68344-36
• Senshi Sōsho Vol.88, Naval armaments and war preparation (2), "And after the outbreak of war", Asagumo Simbun (Japan), October 1975