Japanese submarine I-31

	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 and type	Type B1 submarine
Displacement	2,631 tonnes (2,589 long 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	23.5 knots (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 × single 25 mm (1 in) Type 96 anti-aircraft guns;
Aircraft carried	1 × floatplane
Aviation facilities	1 × catapult

The Japanese submarine I-31 was one of 20 Type B cruiser submarines of the B1 sub-class built for the Imperial Japanese Navy (IJN) during the 1940s.

History
I-31 one day before launching, 12 March 1941
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 and type	Type B1 submarine
Displacement	2,631 tonnes (2,589 long 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	23.5 knots (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 × single 25 mm (1 in) Type 96 anti-aircraft guns
Aircraft carried	1 × floatplane
Aviation facilities	1 × catapult