|Builder:||HM Dockyard, Chatham|
|Laid down:||30 March 1912|
|Commissioned:||18 June 1914|
|Fate:||Scuttled, 4 April 1918|
|Class and type:||E-class submarine|
|Length:||178 ft (54 m)|
|Beam:||15 ft 5 in (4.70 m)|
|Armament:||4 × 18 in (457 mm) torpedo tubes (1 bow, 2 beam, 1 stern)|
HMS E8 was a British E-class submarine built at Chatham Dockyard. She was laid down on 30 March 1912 and was commissioned on 18 June 1914. She cost £105,700. During World War I she was part of the British submarine flotilla in the Baltic.
The early British E-class submarines, from E1 to E8, had a displacement of 652 tonnes (719 short tons) at the surface and 795 tonnes (876 short tons) while submerged. They had a length overall of 180 feet (55 m) and a beam of 22 feet 8.5 inches (6.922 m), and were powered by two 800 horsepower (600 kW) Vickers eight-cylinder two-stroke diesel engines and two 420 horsepower (310 kW) electric motors. The class had a maximum surface speed of 16 knots (30 km/h; 18 mph) and a submerged speed of 10 knots (19 km/h; 12 mph), with a fuel capacity of 50 tonnes (55 short tons) of diesel affording a range of 3,225 miles (5,190 km; 2,802 nmi) when travelling at 10 knots (19 km/h; 12 mph), while submerged they had a range of 85 miles (137 km; 74 nmi) at 5 knots (9.3 km/h; 5.8 mph).
The 'Group 1' E class boats were armed with four 18 inches (460 mm) torpedo tubes, one in the bow, one either side amidships, and one in the stern; a total of eight torpedoes were carried. Group 1 boats were not fitted with a deck gun during construction, but those involved in the Dardanelles campaign had guns mounted forward of the conning tower while at Malta Dockyard. 
E-Class submarines had wireless systems with 1 kilowatt (1.3 hp) power ratings; in some submarines, these were later upgraded to 3 kilowatts (4.0 hp) systems by removing a midship torpedo tube. Their maximum design depth was 100 feet (30 m) although in service some reached depths of below 200 feet (61 m).
On 23 October 1915, she sank the 9,050 ton, 3 funnel armoured cruiser SMS Prinz Adalbert 20 nautical miles (37 km) west of Libau. As the result of this action the submarine's commander, Commander Francis Goodhart, was awarded the Cross of St. George by Tsar Nicholas II. During her time in the Baltic Aksel Berg, who later became the founder of Soviet cybernetics, was her liaison officer.
E8 met her fate on 4 April 1918 outside Helsinki 1.5 nautical miles (2.8 km) off Harmaja Light, Gulf of Finland. She was scuttled by her crew, along with E1, E9, E19, C26, C27, and C35 to avoid seizure by advancing German forces who had landed nearby.
She was salvaged in August 1953 for breaking in Finland.
- Akerman, P. (1989). Encyclopaedia of British submarines 1901–1955. p.150. Maritime Books. ISBN 1-904381-05-7
- "E Class". Chatham Submarines. Retrieved 20 August 2015.
- Keyes, Sir Roger (1934). The Naval Memoirs of Admiral of the Fleet Sir Roger Keyes. Vol. 1: The Narrow Seas to the Dardanelles 1910-1915. London: Thornton Butterworth. p. 68.
- Tall, J.J; Paul Kemp (1996). HM Submarines in Camera An Illustrated History of British Submarines. Sutton Publishing. p. 32. ISBN 0-7509-0875-0.
- "CHATHAM BUILT SUBMARINES: E8 Crew List". www.csubmarine.org. Retrieved 2009-11-22.
- Submarines, War Beneath the Waves, from 1776 to the Present Day, by Robert Hutchinson ISBN 978-0-06-081900-2
- Media related to HMS E8 at Wikimedia Commons
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