Swordfish Class: 2nd Generation Patrol Submarine
Built under the 1929 and 1930 programmes at a cost of £230,000 per boat, all 4 of this class were built at Chatham.
These were much smaller than the large patrol submarines of the Odin, Parthian and Rainbow class.
Also known as the Group 1 'S' class, these boats were the forebears 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.
Sturgeon was the only boat of the class to survive the war, the other three were all lost in the first year of WWII.