Japanese submarine Ro-51
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 Submarine No. 25 on sea trials off Awaji Island in the Seto Inland Sea in June 1920. She was renamed Ro-51 on 1 November 1924. | |
| History | |
|---|---|
 Japan | |
| Name | Submarine No. 25 |
| Builder | Mitsubishi, Kobe, Japan |
| Laid down | 10 August 1918 |
| Launched | 25 October 1919 |
| Completed | 30 June 1920 |
| Commissioned | 30 June 1920 |
| Renamed | Ro-51 on 1 November 1924 |
| Decommissioned | 15 December 1938 |
| Stricken | 1 April 1940 |
| Fate | Hulked 1 April 1940 |
| Renamed | Haisen No. 10 on 1 April 1940 |
| General characteristics | |
| Class & type | Japanese Type L submarine (L1 subclass) |
| Displacement |
|
| Length | 70.59 m (231 ft 7 in) overall |
| Beam | 7.16 m (23 ft 6 in) |
| Draft | 3.90 m (12 ft 10 in) |
| Installed power |
|
| Propulsion |
|
| Speed |
|
| Range |
|
| Test depth | 60 m (197 ft) |
| Crew | 45 |
| Armament |
|
Ro-51, originally named Submarine No. 25, was an Imperial Japanese Navy Type L submarine of the L1 subclass. She was in commission from 1920 to 1938.
The submarines of the Type L1 sub-class were copies of the Group 1 subclass of the British L-class submarine built under license in Japan with technical supervision by the British firm Vickers. The Imperial Japanese Navy procured them in order to acquire advanced British submarine technology, as well as the highly reliable Vickers diesel engines that powered the Type L1 submarines. They displaced 907 tonnes (893 long tons) surfaced and 1,092 tonnes (1,075.2 long tons) submerged. The submarines were 70.59 meters (231 ft 7 in) long and had a beam of 7.16 meters (23 ft 6 in) and a draft of 3.90 meters (12 ft 10 in). They had a diving depth of 60 meters (197 ft).
For surface running, the submarines were powered by two 1,200-brake-horsepower (895 kW) Vickers diesel engines, each driving one propeller shaft. When submerged each propeller was driven by an 800-shaft-horsepower (597 kW) electric motor. They could reach 17 knots (31 km/h; 20 mph) on the surface and 10.2 knots (18.9 km/h; 11.7 mph) underwater. On the surface, they had a range of 5,500 nautical miles (10,200 km; 6,300 mi) at 10 knots (19 km/h; 12 mph); submerged, they had a range of 80 nmi (150 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph).
The submarines were armed with six internal 450 mm (18 in) torpedo tubes — four in the bow and two mounted athwartships and firing on the broadside — and carried a total of ten Type 44 torpedoes. They were also armed with a single 76.2 mm (3 in) gun deck gun.
Construction and commissioning
Ro-51 was laid down as Submarine No. 25 on 10 August 1918 by Mitsubishi at Kobe, Japan.[1] Launched on 25 October 1919,[1] she was completed and commissioned on 30 June 1920.[1]