a beam of 29 ft 10 in and a mean draft of 13 ft 10 in. 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 1 .

For surface running, the boats were powered by two 2200 bhp diesel engines, each driving one propeller shaft.