Japanese submarine Ro-31

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.

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:
Propulsion:
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:

Design and description

The submarines of the Kaichu V sub-class were designed for anti-shipping operations and carried more fuel and had greater range and a heavier gun armament than preceding Kaichu-type submarines. They displaced 866 tonnes (852 long tons) surfaced and 1,036 tonnes (1,020 long tons) submerged. The submarines were 74.22 meters (243 ft 6 in) long and had a beam of 6.12 meters (20 ft 1 in) and a draft of 3.73 meters (12 ft 3 in). They had a diving depth of 45.7 meters (150 ft).

For surface running, the submarines were powered by two 600-brake-horsepower (447 kW) Sulzer diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor. They could reach 13 knots (24 km/h; 15 mph) on the surface and 8.5 knots (15.7 km/h; 9.8 mph) underwater. On the surface, they had a range of 9,000 nautical miles (17,000 km; 10,000 mi) — although the Imperial Japanese Navy officially announced it as 6,000 nautical miles (11,000 km; 6,900 mi) — at 10 knots (19 km/h; 12 mph); submerged, they had a range of 85 nmi (157 km; 98 mi) at 4 knots (7.4 km/h; 4.6 mph).

The submarines were armed with four internal bow 533 mm (21.0 in) torpedo tubes and carried a total of eight torpedoes. They were also armed with a single 120 mm (4.7 in) deck gun and one 6.5 mm machine gun.

Construction, accident, and commissioning

Ro-31 was laid down as Submarine No. 70 on 25 September 1921 by Kawasaki at Kobe, Japan,[1] and was launched on 15 February 1923.[1] Just after completing a pre-completion diving test and submerged sea trial off Kobe on 21 August 1923, she assumed a 30-degree down-angle by the bow and sank in the Seto Inland Sea 2 nautical miles (3.7 km; 2.3 mi) off Kariya Point on Awaji Island when a hatch was opened prematurely, the wake of a passing ship swamped her, and the mismanagement of various valves caused her crew to lose control of her.[2][3][4] Eighty-eight men — 46 Imperial Japanese Navy personnel and 42 shipyard workers — died in the disaster.[1] Five men survived the sinking.[4][5][6] Her commanding officer was among the survivors, and on 14 March 1924 he was found responsible for the loss of his submarine and fined 100 yen.[7]

Submarine No 70 was refloated on 24 October 1924 and dismantled.[1] She was laid down again on 20 December 1924 to be rebuilt with the materials used in her original construction.[1] She was relaunched on 25 September 1926 and was attached to the Sasebo Naval District the same day.[1] She was completed and commissioned on 10 May 1927 and was renamed Ro-31 that day.[1]

Service history

Pre-World War II

Ro-31 remained attached to the Sasebo Naval District throughout the pre-World War II period.[1] Upon commissioning, she was assigned to the Sasebo Naval District. On 15 November 1934, she was reassigned to Submarine Division 25.[1] She was decommissioned and placed in the Fourth Reserve on 15 December 1938.[1]

World War II

Ro-31 was still in reserve when the Pacific Campaign of World War II began on 7 December 1941 (8 December 1941 in East Asia) with the Japanese attack on Pearl Harbor, Hawaii. She was recommissioned on 9 February 1942 to serve as a training submarine, initially attached to the Kure Naval District beginning on the day she was recommissioned, then to the Yokosuka Naval District from 14 July 1942 to 15 January 1943, and then to the Kure Naval District again until 15 January 1944, when she again was decommissioned and placed in the Fourth Reserve in the Kure Naval District.[1] The Japanese struck her from the Navy list on 25 May 1945.[1]

Disposal

Ro-31 was on the Japanese coast in the western Seto Inland Sea awaiting disposal when hostilities between Japan and the Allies ended on 15 August 1945.[1] She surrendered to the Allies on 2 September 1945.[1] The United States Navy scuttled her along with the Japanese submarines Ha-207, Ha-210, Ha-215, Ha-216, Ha-217, Ha-219, and Ha-228 off Sasebo Bay on 5 April 1946.[1]

Notes
  1. "RO-31 ex No-70". iijnsubsite.info. 2018. Retrieved 10 October 2020.
  2. Romig, Mary F., Fata Submarine Accidents: A Bibliography 1900–1965, Santa Monica, California: The Rand Corporation, November 1966, p. 11.
  3. "Submarine Accidents Involving Loss of Life Since World War," Navy Appropriation Bill for 1929, Seventieth Congress of the United States, Washington, D.C.: Government Printing Office, 1928, p. 107.
  4. Airship Investigation: Report of Col. Henry Breckenridge, Washington, D.C.: Government Printing Office, 1933, p. 55.
  5. Gray, Edwyn, Disasters of the Deep: A Comprehensive Survey of Submarine Accidents & Disasters, Appendix II: Naval Submarines Lost By Accident or Error Since 1900, Barnsley, South Yorkshire, United Kingdom: Pen & Sword Books, 2003, ISBN 0 85052 987 5, unpaginated.
  6. niehorster.org Imperial Japanese Navy RO-Boats (2nd Class Submarines) Accessed 11 October 2020
  7. Anonymous, "Commander of Ill-Fated Submarine Is Fined 100 Yen," The Nippu Jiji, March 14, 1924, Page 1.

References
  • "Rekishi Gunzō"., History of Pacific War Vol.17 I-Gō Submarines, Gakken (Japan), January 1998, ISBN 4-05-601767-0
  • 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
  • The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III, Ushio Shobō (Japan), September 1980, Book code 68343-44
  • The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition", Ushio Shobō (Japan), February 1988, Book code 68344-36
  • The Maru Special, Japanese Naval Vessels No.133 Japanese Submarines II "Revised edition", Ushio Shobō (Japan), March 1988, Book code 68344-37
  • The Maru Special, Japanese Naval Vessels No.135 Japanese Submarines IV, Ushio Shobō (Japan), May 1988, Book code 68344-39
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