Japanese submarine I-181

The Japanese submarine I-181 was a attack submarine of the KD7 sub-class built for the Imperial Japanese Navy (IJN) during the 1940s. She was lost with all hands when she was ran aground in New Guinea after a battle with American ships in early 1944.

Design and description
The submarines of the KD7 sub-class were medium-range attack submarines developed from the preceding KD6 sub-class. They displaced 1833 LT surfaced and 2602 LT submerged. The submarines were 105.5 m long, had a beam of 8.25 m and a draft of 4.6 m. The boats had a diving depth of 80 m and a complement of 86 officers and crewmen.

For surface running, the boats were powered by two 4000 bhp diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 900 hp electric motor. They could reach 23 kn on the surface and 8 kn underwater. On the surface, the KD7s had a range of 8000 nmi at 16 kn; submerged, they had a range of 50 nmi at 5 kn.

The boats were armed with six internal 53.3 cm torpedo tubes, all in the bow. They carried one reload for each tube; a total of a dozen torpedoes. They were originally intended to be armed with two twin-gun mounts for the 25 mm Type 96 anti-aircraft gun, but a 120 mm deck gun for combat on the surface was substituted for one 25 mm mount during construction.

Construction and career
Built by the Kure Naval Arsenal, the boat was laid down as I-81 and renamed I-181 in 1942. She was launched on 2 May 1942 and completed on 24 May 1943. I-181 ran aground in Kelanoa Harbour, New Guinea, and wrecked after a battle with an American destroyer and a PT boat with the loss of all 89 officers and crewmen. She was struck from the Navy List on 30 April 1944.