Japanese submarine Ro-116
Ro-116 was an Imperial Japanese Navy "Ro-100"-class submarine. Completed and commissioned in January 1944, she served in World War II and was sunk in May 1944 during her second war patrol. Design and description. The "Ro-100" class was a medium-sized, coastal submarine derived from the preceding "Kaichū" type. They displaced surfaced and submerged. The submarines were long, had a beam of and a draft of . They had a double hull and a diving depth of . For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was  driven by a electric motor. They could reach on the surface and underwater. On the surface, the "Ro-100"s had a range of at ; submerged, they had a range of at . The boats were armed with four internal bow torpedo tubes and carried a total of eight torpedoes. They were also armed with two single mounts for Type 96 anti-aircraft guns or a single L/40 AA gun. Construction and commissioning. "Ro-116" was laid down as Submarine No. 407 on 16 January 1943 by Kawasaki at Senshu, Japan. She was renamed Ro-116 on 5 July 1943 and was attached provisionally to  the Yokosuka Naval District that day. She was launched on 13 September 1943, then was towed to Kawasaki's shipyard at Kobe, Japan, for fitting-out. She was completed and commissioned at Kobe on 21 January 1944. Service history. January–March 1944. Upon commissioning, "Ro-116" was attached formally to the Yokosuka Naval District and was assigned to Submarine Squadron 11 for workups. She called at the 3rd Fuel Depot at Tokuyama, Japan, from 28 to 29 March 1944 to refuel. First war patrol. "Ro-116" got underway from Japan on 31 March 1944 along with the submarine for her first war  patrol, ordered to intercept an Allied task force operating in the vicinity of the Palau Islands. She did not find the task force, and returned to Japan on 13 April 1944. Second war patrol. On 4 May 1944, "Ro-116" was reassigned to Submarine Division 51 in Submarine Squadron 7 in the 6th Fleet. She departed Kure, Japan, that day bound for Saipan in the Mariana Islands, which she reached on 10 May 1944. "Ro-116" got underway from Saipan on 15 May 1944 for her second war patrol with orders to join the submarines , , , , , and in forming a submarine picket line  north of the Admiralty Islands designated Scouting Line NA. The picket line was tasked with providing warning of any move toward the Palau Islands by Allied invasion forces. On 18 May 1944, U.S. Navy signals intelligence personnel intercepted and decrypted Japanese signals indicating the formation of Scouting Line NA between Truk and the Admiralties. A hunter-killer group composed of the destroyer escorts , , and departed Purvis Bay in the Solomon Islands to attack the submarines involved. Loss. At 01:20 on 24 May 1944, "Ro-116" was on the surface north-northwest of Kavieng on New Ireland when "George" gained radar contact  on her at a range of . "Ro-116" submerged at 01:28, causing "George" to lose contact. At 01:50, however, "England" made sonar contact on "Ro-116" at a range of . Operating at a depth of , "Ro-116" began to emit sound impulses to jam "England"′s sonar and to make violent evasive maneuvers intended to disrupt "England"′s sonar by creating underwater wakes. "England" aborted her first two attack runs, then fired a barrage of 24 Hedgehog projectiles, at least three of which hit and sank "Ro-116" at . After sunrise, debris was recovered from the ocean's surface in the area. On 25 June 1944 , the Imperial Japanese Navy declared "Ro-116" to be presumed lost north of the Admiralty Islands with all 56 men on board. The Japanese struck her from the Navy list on 10 August 1944.