HMS E31

HMS E31 was a British E-class submarine built by Scotts, Greenock. She was laid down in December 1914, commissioned on 8 January 1916, and sold for scrap on 6 September 1922.

Design
Like all post-E8 British E-class submarines, E31 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. E31 was capable of operating submerged for five hours when travelling at 5 kn.

E31 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.

Crew
Her complement was three officers and 28 men.

Service history
HMS E31 was involved in a curious incident when she was operating with the sea plane carrier HMS Engadine (1911) in the North Sea in an air raid on the Zeppelin sheds at Tondern on 4 May 1916. While on a mission, LZ 32 was spotted by light cruisers HMS Galatea (1914) and HMS Phaeton (1914) who opened fire on the airship. Just as they were doing this HMS E31 was operating with the sea plane carrier HMS Engadine (1911) in the North Sea in an air raid on the Zeppelin sheds at Tondern on 4 May 1916. E31 surfaced and spotted the airship, but being vulnerable on the surface, the sub dived to avoid attack. When the submarine put its periscope up, it observed that the Zeppelin was losing altitude after being hit by shells from HMS Galatea (1914) and HMS Phaeton (1914). E31 then surfaced just in time to get in the fatal shot and brought the Zeppelin down. HMS E31 then proceeded to rescue seven survivors from the crew of LZ 32.