The Porpoise class was an eight-boat class of diesel-electric submarines operated by the Royal Navy. This class was originally designated patrol submarines, then attack. They were the first conventional British submarines to be built after the end of World War II. Their design was, in many ways, influenced by the German World War II-era Type XXI U-boats.
Design
The Porpoise-class submarines were larger but shorter than their T-class predecessors and used a much improved steel known as UXW. This, and improved design and construction techniques allowed much deeper diving. It was found in tests that the unusually long engine room was liable to collapse, so there were extra large frames in this section, which proved to be something of an operational inconvenience.
| Broken up 1977
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| 25 October 1957. Built by Vickers at Barrow-in-Furness
| Sunk as a target on 3 August 1983
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| 30 May 1957.