Japanese submarine Ro-25

History
Japan
Name	Submarine No. 43
Builder	Sasebo Naval Arsenal, Sasebo, Japan
Laid down	19 February 1920
Launched	17 July 1920
Completed	25 October 1921
Commissioned	25 October 1921
Renamed	Ro-25 on 1 November 1924
Decommissioned	26 April 1924
Recommissioned	4 May 1925
Stricken	1 April 1936
Fate	Scrapped 1936
General characteristics
Class and type	Kaichū type submarine (K3 subclass)
Displacement	752 tonnes (740 long tons) surfaced 1,013 tonnes (997 long tons) submerged
Length	70.10 m (230 ft 0 in) overall
Beam	6.12 m (20 ft 1 in)
Draft	3.70 m (12 ft 2 in)
Installed power	2,900 bhp (2,200 kW) (diesel) 1,200 hp (890 kW) (electric motor)
Propulsion	Diesel-electric 2 × Sulzer Mark II diesel engine, 75 tons fuel 2 × electric motor 2 x shafts
Speed	16.5 knots (30.6 km/h; 19.0 mph) surfaced 8.5 knots (15.7 km/h; 9.8 mph) submerged
Range	6,000 nmi (11,000 km; 6,900 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	46
Armament	6 × 450 mm (18 in) bow , 2 x external on upper deck) 10 x Type 44 torpedoes 1 × 76.2 mm (3.00 in) gun

Ro-25, originally named Submarine No. 43, was an

The submarines of the Kaichu III sub-class were a slightly improved version of the preceding Kaichu II subclass, the man difference being an increase in diving depth from 30 to 45.7 meters (98 to 150 ft).[1] They displaced 752 tonnes (740 long tons) surfaced and 1,013 tonnes (997 long tons) submerged. The submarines were 70.10 meters (230 ft 0 in) long and had a beam of 6.12 meters (20 ft 1 in) and a draft of 3.70 meters (12 ft 2 in).

For surface running, the submarines were powered by two 1,450-

Upon commissioning, Submarine No. 43 was attached to the Sasebo Naval District, to which she remained attached throughout her career.^[2] On 15 December 1921, she was assigned to Submarine Division 22 and to the Mako Defense Division at Mako in the Pescadores Islands.^[2] On 1 December 1922, Submarine Division 22 was reassigned to the Sasebo Defense Division.^[2]

On 19 March 1924, Submarine No. 43 was taking part in maneuvers off the harbor at Sasebo when she collided with the light cruiser Tatsuta.^[3][4][5] Tatsuta sliced through Submarine No. 43′s conning tower,^[5] and Submarine No. 43 sank 3 nautical miles (5.6 km; 3.5 mi) off Sasebo in 156 feet (48 m) of water.^[3] Using a telephone floated from the sunken submarine, a rescue party on the surface established contact with the crewmen trapped aboard her, who reported ever-deteriorating conditions^[3] before falling silent about ten hours after she sank.^[5] Submarine No. 43′s entire crew of 46 suffocated.^[3]

Submarine No. 43 was partially raised and towed to Sasebo, where she arrived on 13 April 1924 so that

Ro-25 was stricken from the Navy list on 1 April 1936.[2] She subsequently was scrapped during 1936.^[2]

Commemoration

The Submarine No. 43 Memorial, a gray obelisk commemorating the 1924 sinking of Submarine No. 43, stands on Udogoe, overlooking Sasebo.^[5] It provides a vantage point from which visitors can see the area in which she sank.^[5]

Notes

References

• "Rekishi Gunzō"., History of Pacific War Vol.17 I-Gō Submarines,
  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

• Photo of Submarine No. 43 Memorial at Wayfarer Daves Travel and History