I-31 one day before launching, 12 March 1941
History
Empire of Japan
Name	I-31
Builder	Yokosuka Naval Yard
Laid down	6 December 1939
Launched	13 March 1941
Completed	30 May 1942
Fate	Sunk, 13 May 1943
General characteristics
Class & type	Type B1 submarine
Displacement	2,631tonnes (2,589long tons) surfaced 3,713 tonnes (3,654 long tons) submerged
Length	108.7 m (356 ft 8 in) overall
Beam	9.3 m (30 ft 6 in)
Draft	5.1 m (16 ft 9 in)
Installed power	12,400 bhp (9,200 kW) (diesel) 2,000 hp (1,500 kW) (electric motor)
Propulsion	Diesel-electric 2 ×diesel engine 2 × electric motor
Speed	23.5knots (43.5 km/h; 27.0 mph) surfaced 8 knots (15 km/h; 9.2 mph) submerged
Range	14,000 nmi (26,000 km; 16,000 mi) at 16 knots (30 km/h; 18 mph) surfaced 96 nmi (178 km; 110 mi) at 3 knots (5.6 km/h; 3.5 mph) submerged
Test depth	100 m (330 ft)
Crew	94
Armament	6 × bow 533 mm (21 in)torpedo tubes 1 ×14 cm (5.5 in)deck gun 2 × single25 mm (1 in) Type 96anti-aircraft guns
Aircraft carried	1 ×floatplane
Aviation facilities	1 ×catapult

TheJapanese submarineI-31 was one of 20Type Bcruiser submarines of the B1sub-class built for theImperial Japanese Navy (IJN) during the 1940s.

The Type B submarines were derived from the earlier KD6 sub-class of theKaidai class and were equipped with an aircraft to enhance their scouting ability. Theydisplaced 2,631 tonnes (2,589 long tons) surfaced and 3,713 tonnes (3,654 long tons) submerged. The submarines were 108.7 meters (356 ft 8 in) long, had abeam of 9.3 meters (30 ft 6 in) and adraft of 5.1 meters (16 ft 9 in). They had a diving depth of 100 meters (330 ft).^[1]

For surface running, the boats were powered by two 6,200-brake-horsepower (4,623 kW)diesel engines, each driving onepropeller shaft. When submerged each propeller was driven by a 1,000-horsepower (746 kW)electric motor. They could reach 23.6knots (43.7 km/h; 27.2 mph) on the surface and 8 knots (15 km/h; 9.2 mph) underwater.^[2] On the surface, theB1s had a range of 14,000nautical miles (26,000 km; 16,000 mi) at 16 knots (30 km/h; 18 mph); submerged, they had a range of 96 nmi (178 km; 110 mi) at 3 knots (5.6 km/h; 3.5 mph).^[3]

The boats were armed with six internal bow 53.3 cm (21.0 in)torpedo tubes and carried a total of 17torpedoes. They were also armed with a single140 mm (5.5 in)/40deck gun and two single mounts for25 mm (1 in) Type 96anti-aircraft guns.^[3] In the Type Bs, the aircrafthangar was faired into the base of theconning tower. A singlecatapult was positioned on the forward deck.^[3]

In November 1942, I-31 was spotted doing reconnaissance with its seaplane offSuva,Fiji.^[4]

On 12 May 1943 I-31 attacked theUSSPennsylvania and theUSSSanta Fe (CL-60) with torpedoes nine miles northeast ofHoltz Bay, all missed.^[5]On 12 May 1943, near Holtz Bay,Attu, her periscope was sighted by American destroyers,Edwards andFrazier, who immediately opened fire.I-31 dove quickly but not beforeEdwards scored hits. The destroyers quickly made sonar contact and began a series of depth charge attacks until, after surviving for 10 hours, she was sunk byFrazier on 13 May.^[6][7][8]

• Bagnasco, Erminio (1977).Submarines of World War Two. Annapolis, Maryland: Naval Institute Press.ISBN 0-87021-962-6.
• Boyd, Carl & Yoshida, Akikiko (2002).The Japanese Submarine Force and World War II. Annapolis, Maryland: Naval Institute Press.ISBN 1-55750-015-0.
• 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.
• Hashimoto, Mochitsura (1954).Sunk: The Story of the Japanese Submarine Fleet 1942 – 1945. Colegrave, E.H.M. (translator). London: Cassell and Company. ASIN B000QSM3L0.
• Milanovich, Kathrin (2021). "The IJN Submarines of the I 15 Class". In Jordan, John (ed.).Warship 2021. Oxford, UK: Osprey Publishing. pp. 29–43.ISBN 978-1-4728-4779-9.
• Stille, Mark (2007).Imperial Japanese Navy Submarines 1941-45. New Vanguard. Vol. 135. Botley, Oxford, UK: Osprey Publishing.ISBN 978-1-84603-090-1.

"USS Amberjack: Lost around 16 February 1943". The USS Flier Project. Archived fromthe original on 19 June 2015. Retrieved18 June 2015.

52°32′31″N172°10′37″E / 52.542°N 172.177°E /52.542; 172.177

• 1941 ships
• 1943 in Alaska
• World War II submarines of Japan
• Japanese submarines lost during World War II
• Ships built by Yokosuka Naval Arsenal
• Ships of the Aleutian Islands campaign
• Shipwrecks of the Alaska coast
• Type B1 submarines
• World War II shipwrecks in the Pacific Ocean
• Maritime incidents in May 1943

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