HMS Rainbow was a submarine built for the Royal Navy during the 1930s.
The Rainbow-class submarines were designed as improved versions of the Parthian class and were intended for long-range operations in the Far East. The submarines had a length of 287feet overall, a beam of 29feet and a mean draft of 13feet. They displaced 1772LT on the surface and 2030LT submerged. The Rainbow-class submarines had a crew of 56 officers and ratings. They had a diving depth of 300feet.[1]
For surface running, the boats were powered by two 22000NaN0 diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 660hp electric motor. They could reach 17.5kn on the surface and underwater. On the surface, the boats had a range of 7050nmi at and 62nmi at submerged.[1]
The boats were armed with six 21inches torpedo tubes in the bow and two more in the stern. They carried six reload torpedoes for a grand total of fourteen torpedoes. They were also armed with a QF 4.7-inch (120 mm) Mark IX deck gun.[2]
Rainbow ran aground in the English Channel off Ventnor, Isle of Wight, on 22 January 1932. She was refloated later the same day.[3]
Rainbow served in the Far East until 1940, when she moved to the Mediterranean. She left for a patrol off Calabria on 23 September 1940[4] and was due to be back in Alexandria on 16 October, she was last heard from on 25 September. She is believed to have been sunk on 4 October in a collision with the Italian merchant ship Antonietta Costa, which reported striking a submerged object at 03:30, followed by a huge underwater explosion while sailing in convoy from Albania on that date.[5]
Until 1988 it was believed that Rainbow had been sunk by the, but eventually it was determined that was the submarine that Enrico Toti sank.