Japanese submarine Ro-45

The submarines of the K6 sub-class were versions of the preceding K5 sub-class with greater range and diving depth.[1] They displaced 1,133 metric tons (1,115 long tons) surfaced and 1,470 metric tons (1,447 long tons) submerged. The submarines were 80.5 meters (264 ft 1 in) long overall, had a beam of 7 meters (23 ft) and a draft of 4.07 meters (13 ft 4 in). They had a operational diving depth of 80 meters (260 ft).[2]

For surface running, the boats were powered by two 2,100-brake-horsepower (1,566 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor.[3] They could reach 19.75 knots (36.58 km/h; 22.73 mph) on the surface and 8 knots (15 km/h; 9.2 mph) underwater. On the surface, the K6s had a range of 11,000 nautical miles (20,000 km; 13,000 mi) at 12 knots (22 km/h; 14 mph); submerged, they had a range of 45 nmi (83 km; 52 mi) at 5 knots (9.3 km/h; 5.8 mph).[1]

The boats were armed with four internal bow 53.3 cm (21.0 in) torpedo tubes and carried a total of ten torpedoes. They were also armed with a single 40-caliber 76.2 mm (3 in) anti-aircraft (AA) gun and two single 25 mm (1 in) AA guns.[1]

Ro-45 was laid down as Submarine No. 386 on 20 October 1942 by Mitsubishi at Kobe, Japan.[4] She was launched on 21 July 1943 and was renamed Ro-45 on that day.[4] She was completed and commissioned on 11 January 1944.[4]

Upon commissioning, Ro-45 was attached to the Maizuru Naval District and assigned to Submarine Squadron 11 for workups.[4] On 14 April 1944, she was reassigned to Submarine Division 34 in the 6th Fleet.[4] She departed Kure, Japan, on 16 April 1944 bound for Truk, which she reached on 27 April 1944.[4]

While Ro-45 was at Truk, the aircraft carriers of United States Navy Task Force 58 began two days of airstrikes against Truk on 29 April 1944.[4] On 30 April 1944, during the second day of strikes, the commander of Submarine Squadron 7 ordered Ro-45 and the submarines I-16, I-176, Ro-44, Ro-106, Ro-108, and Ro-115 to intercept Task Force 58.[4]

At 06:21 local time on 30 April 1944, the U.S. Navy destroyer USS MacDonough (DD-351) made radar contact on an unidentified vessel on the surface 40 nautical miles (74 km; 46 mi) south of Truk.[4] The contact disappeared from radar, indicating a submerging submarine.[4] MacDonough subsequently gained sonar contact on the submarine and, with an F6F Hellcat fighter from Fighter Squadron 28 (VF-28) aboard the light aircraft carrier USS Monterey (CVL-26) providing spotting support, made two depth-charge attacks.[4][5] The destroyer USS Stephen Potter (DD-538) also joined the attack.[4] The destroyer crews noted several underwater explosions after the last depth charge detonated, marking the end of the submarine, which sank at 06°13′N 151°19′E.[4] Oil and debris later rose to the surface.[4]

No other Japanese submarine made contact with Task Force 58, and the submarine MacDonough and Stephen Potter sank probably was Ro-45.[4] On 20 May 1944, the Imperial Japanese Navy declared her to be presumed lost off Truk with all 74 men on board.[4] She was stricken from the Navy list on 10 July 1944.[4]

Some sources suggest that Ro-45 was sunk off Saipan in the Mariana Islands by the U.S. submarine USS Seahorse (SS-304) on 20 April 1944, but that is incorrect because Ro-45 remained active after that date.[4] Other sources incorrectly identify the Japanese submarine sunk on 30 April 1944 as I-174,[4] but I-174 was sunk on 12 April 1944.[6]

• Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-962-6.
• Carpenter, Dorr B. & Polmar, Norman (1986). Submarines of the Imperial Japanese Navy 1904–1945. London: Conway Maritime Press. ISBN 0-85177-396-6.
• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Hackett, Bob; Kingsepp, Sander (2011). "IJN Submarine RO-45: Tabular Record of Movement". SENSUIKAN! Stories and Battle Histories of the IJN's Submarines. Combinedfleet.com. Retrieved 18 August 2015.
• Hackett, Bob; Sander Kingsepp (2003). "Kaichu Type". Sensuikan!. Combinedfleet.com. Retrieved 10 May 2009.