Japanese submarine Ro-31

Ro-31 in 1935.
History
Japan
Name	Submarine No. 70
Builder	Kawasaki, Kobe, Japan
Laid down	25 September 1921
Launched	15 February 1923
Fate	Sank 21 August 1923 Salvaged and dismantled
Laid down	20 December 1924 (rebuild)
Launched	25 September 1926 (relaunch)
Completed	10 May 1927
Commissioned	10 May 1927
Renamed	Ro-31 on 10 May 1927
Decommissioned	15 December 1938
Recommissioned	9 February 1942
Decommissioned	31 January 1944
Stricken	25 May 1945
Fate	Surrendered 2 September 1945 Scuttled 5 April 1946
General characteristics
Class and type	Kaichū type submarine (K5 subclass)
Displacement	866 tonnes (852 long tons) surfaced 1,047 tonnes (1,030 long tons) submerged
Length	74.22 m (243 ft 6 in) overall
Beam	6.12 m (20 ft 1 in)
Draft	3.73 m (12 ft 3 in)
Installed power	1,200 bhp (890 kW) (diesel) 1,200 hp (890 kW) (electric motor)
Propulsion	Diesel-electric 2 × Sulzer Mark I diesel engine, 143 tons fuel 2 × electric motor
Speed	13 knots (24 km/h; 15 mph) surfaced 8.5 knots (15.7 km/h; 9.8 mph) submerged
Range	9,000 nmi (17,000 km; 10,000 mi) at 10 knots (19 km/h; 12 mph) surfaced 85 nmi (157 km; 98 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth	45.7 m (150 ft)
Crew	44
Armament	4 × bow 533 mm (21 in) torpedo tubes 1 × 120 mm (4.7 in) gun 1 × 6.5 mm machine gun

Ro-31, originally named Submarine No. 70, was an Imperial Japanese Navy Kaichu-Type submarine of the Kaichu V (Toku Chu) subclass. After a diving accident in 1923 prior to completion, she was salvaged, rebuilt, and completed in 1927. She served in a training role during World War II, surrendered at the end of the war in September 1945, and was scuttled in April 1946.