Shark Class: 2nd Generation Patrol Submarine
Built under the 1931 to 1935 programmes at a cost of £230,000 to £245,000 per boat.
Of the 8 boats in this class, 4 were built at Chatham.
Although much smaller than the large patrol submarines of the Odin, Parthian and Rainbow class, these were 6 feet longer than the Group 1 Swordfish Class.
Also known as the Group 2 'S' class, these boats would be the final stepping stone to the design of the very successful Group 3 'S' class.
During the design, more emphasis had been placed on safety which resulted in the provision of two escape hatches. Special lockers were placed in the escape compartments to hold the Davis Submerged Escape Equipment (DSEA). If the crew had to escape, these units allowed each individual to breathe oxygen whilst making their ascent. The escape compartments were in the forward accommodation space and the after stokers mess.
The boat was divided into six compartments by five watertight bulkheads.
In July 1944, Sunfish was transferred to the Soviet Navy. Soon after leaving the UK for her passage home, she failed to provide the required recognition signal and was sunk by Coastal Command.
Of the remaining 7 boats, only Sealion (deliberately sunk as A/S target in March 1945) and Seawolf (scrapped November 1945) survived WWII