HMS E51 was a British E-class submarine built originally from Yarrow, Scotstoun, but transferred to Scotts, Greenock on 3 March 1915. HMS E51 was launched on 30 November 1916 and commissioned on 27 January 1917. E51 was sold for scrap on 13 October 1921.

Design

Like all post-E8 British E-class submarines, E51 had a displacement of 662 LT at the surface and 807 LT while submerged. She had a total length of 180 ft and a beam of 22 ft. She was powered by two 800 hp Vickers eight-cylinder two-stroke diesel engines and two 420 hp electric motors. The submarine had a maximum surface speed of 16 kn and a submerged speed of 10 kn. British E-class submarines had fuel capacities of 50 LT of diesel and ranges of 3255 mi when travelling at 10 kn. E51 was capable of operating submerged for five hours when travelling at 5 kn. E51 was armed with a 12-pounder 76 mm QF gun mounted forward of the conning tower. She had five 18 inch (450 mm) torpedo tubes, two in the bow, one either side amidships, and one in the stern; a total of 10 torpedoes were carried. E-Class submarines had wireless systems with 1 kW power ratings; in some submarines, these were later upgraded to 3 kW systems by removing a midship torpedo tube. Their maximum design depth was 100 ft although in service some reached depths of below 200 ft. Some submarines contained Fessenden oscillator systems.