A K-class submarine steaming off the stern of a Royal Naval battleship

Despite Lord Fisher's warning to Sir John Jellicoe in 1913 that: 'The most fatal error imaginable would be to put steam engines in a submarine', between 1916 and 1918 the navy ordered no less than 17 steam submarines from Vickers of Barrow at the huge cost of £300,000 each. Based on a design by Eustace D'Eyncourt but with modifications by Fisher himself, these submarines were 339 feet long with a surface displacement of 1800 tons, and 2600 tons submerged. Each submarine had seven power units, comprising two steam turbines for surface propulsion, four electric motors for submergence, and one diesel motor, allowing a healthy maximum surface speed of 23.5knots carrying an armament of three guns, and ten 18in. torpedo tubes. Although officially known as the 'K' Class, they were more popularly referred to by their sailors as the 'Suicide Club': Condensation in the engine rooms caused the main switchboards to short circuit, which in turn lead to fires, and the sheer heat to severe burns. Of the 17 that were built, 16 had major accidents. Fisher ruefully concluded: 'I have not yet mastered on what basis our submarines harm the enemy more than ourselves'.