Rainbow-class submarine

The Rainbow-class submarine or R class was a quartet of patrol submarines built for the Royal Navy in the early 1930s.

Design and description
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 287 ft overall, a beam of 29 ft and a mean draft of 13 ft. They displaced 1772 LT on the surface and 2030 LT submerged. The Rainbow-class submarines had a crew of 56 officers and ratings. They had a diving depth of 300 ft.

For surface running, the boats were powered by two 2200 bhp diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 660 hp electric motor. They could reach 17.5 kn on the surface and 9 kn underwater. On the surface, the boats had a range of 7050 nmi at 9.2 kn and 62 nmi at 4 kn submerged.

The boats were armed with six 21-inch 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.

Boats
Six boats were ordered in February 1929 but, following the May 1929 general election, the new government suspended the construction of two boats in August due to economic considerations; they were subsequently cancelled.

It is often stated that the ITALIAN SUBMARINE Enrico Toti sank HMS Rainbow. However, the submarine Enrico Toti sank was HMS Triad (N53).