Japanese submarine Ro-52

Ro-52, originally named Submarine No. 26, was an Imperial Japanese Navy Type L submarine of the L1 subclass. She was commissioned in 1920, sank accidentally in 1923 and again in 1925, was refloated and repaired each time, and was decommissioned in 1932.

Design and description
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 893 LT surfaced and 1,075.2 LT submerged. The submarines were 70.59 m long and had a beam of 7.16 m and a draft of 3.90 m. They had a diving depth of 60 m.

For surface running, the submarines were powered by two 1,200 bhp Vickers diesel engines, each driving one propeller shaft. When submerged each propeller was driven by an 800 shp electric motor. They could reach 17 kn on the surface and 10.2 kn underwater. On the surface, they had a range of 5,500 nmi at 10 kn; submerged, they had a range of 80 nmi at 4 kn.

The submarines were armed with six internal 450 mm 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 gun deck gun.

Construction and commissioning
Ro-52 was laid down as Submarine No. 26 on 10 August 1918 by Mitsubishi at Kobe, Japan. Launched on 9 March 1920, she was completed and commissioned on 30 November 1920.

Service history
Upon commissioning, Submarine No. 26 was attached to the Yokosuka Naval District and assigned to Submarine Division 3. On 1 December 1920, Submarine Division 3 was assigned to Submarine Squadron 1 in the 1st Fleet. Submarine Division 3 was reattached to the Yokosuka Naval District on 1 December 1921 and was assigned that day to the Yokosuka Defense Division, then was reassigned on 1 June 1922 to the Ominato Defense Division. On 1 December 1922, Submarine No. 26 was attached to the Kure Naval District and reassigned to Submarine Division 11, in both of which she remained for the rest of her active career. She was assigned to the Kure Defense Division on 1 December 1922.

On 13 March 1923, Submarine No.26 collided with the steamer SS Ryosei Maru off Hiroshima, Japan. On 29 October 1923, Submarine No. 26 was moored to a buoy alongside the protected cruiser JAPANESE CRUISER Yahagi in the harbor at Kure, Japan, during a memorial service for Submarine No. 70— which had sunk in August 1923 with heavy loss of life — with the admiral commanding the Kure Naval District in attendance when she suddenly began to sink rapidly by the bow. She struck the buoy, then began to sink quickly by the stern, and within 20 minutes she had settled on the bottom at a depth of 8 fathom with only her periscope and wireless mast protruding above the surface. Her entire crew survived the sinking and another submarine′s crew rescued everyone who had been aboard. In its immediate aftermath, the sinking was attributed to flooding in a water tank, but the investigation into the incident concluded that she sank when her torpedo tube doors opened accidentally. Plans were made immediately to salvage her, without any particular difficulties anticipated. She was refloated on 17 November 1923, repaired, and returned to service.

Submarine No. 26′s duty in the Kure Guard District ended on 1 December 1923, but she continued to serve in the Kure Naval District and was renamed Ro-52 on 1 November 1924. On 29 October 1925, Ro-52 sank again without loss of life while tied up at a pier because of flooding through a torpedo tube that an investigation attributed to carelessness. She again was refloated and repaired. She was decommissioned and stricken from the Navy list on 1 April 1932.