Built as a submarine under yard no 818 by Vickers Armstrong, Barrow for the Royal Navy.
06 June 1942 laid down.
24 February 1943 launched as P-318. One of the T-Class submarines.
Displacement: 1,290 ton surfaced, 1,560 ton submerged, dim. 84.24 x 7.77 x 4.45m (surfaced draught).
Powered by twin diesel engines 2,500 hp. (1.86 MW) each, twin electro motors 1,450 hp (1.08 MW) each, twin shafts, speed 15.5 knots surfaced, 9 knots submerged.
Range:4,500 nautical miles at 11 knots (8,330 km at 20 km/h) surfaced
Test depth 91 metres.
Armament: Six internal forward-facing 21-inch (533 mm) torpedo tubes, two external forward-facing torpedo tubes, one external rear-facing torpedo tubes, six reload torpedoes, 1 x 4-inch (102 mm) deck gun, three anti-aircraft machine guns
Complement: 61
02 June 1943 commissioned as the HMS TANTALUS.
HMS TANTALUS was a British submarine of the third group of the T class. She was built as P318 by Vickers Armstrong, Barrow, and launched on 24 February 1943. So far she has been the only ship of the Royal Navy to bear the name TANTALUS, after the mythological TANTALUS, son of Zeus.
Service
TANTALUS served in the Far East for much of her wartime career. She sank the Malaysian tug KAMPUNG BESAR, and the Malaysian PULO SALANAMA in April 1944; she went on to sink the Japanese army cargo ships AMAGI MARU and HIYOSHI MARU, the Japanese cargo ship HACHIJIN MARU, the Japanese coaster PALANG MARU, the Japanese fishing vessel TAISEI MARU No. 12, a Japanese tug and three barges, an unknown Japanese vessel, and a Siamese sailing vessel, whilst claiming to have damaged a second. TANTALUS also damaged a tug and the Japanese submarine chaser Ch 1. She also attacked, but missed the Japanese submarine I-166, which was sunk later that day by HMS TELEMACHUS.
TANTALUS survived the war and continued in service with the Royal Navy, finally being scrapped at Milford Haven in November 1950.
https://en.wikipedia.org/wiki/HMS_TANTALUS_(P318)
Gibraltar 2020 80p sg?, scott?