HMS A7

HMS A7 was an A-class submarine built for the Royal Navy in the first decade of the 20th century. She sank in a training accident in 1914 with the loss of her entire crew. Efforts to salvage her failed and her wreck is a protected site. Diving on her is prohibited without a licence from the Ministry of Defence.

HMS A7
History
United Kingdom
Name: HMS A7
Builder: Vickers Barrow-in-Furness
Laid down: 19 February 1903
Launched: 23 January 1905
Commissioned: 16 January 1905
Fate: Sunk in Whitsand Bay, 16 January 1914
General characteristics
Class and type: A-class submarine
Displacement:
  • 190 long tons (193 t) surfaced
  • 206 long tons (209 t) submerged
Length: 105 ft (32.0 m)
Beam: 12 ft 9 in (3.9 m)
Draught: 10 ft 8 in (3.3 m)
Installed power:
Propulsion:
  • 1 × 16-cylinder Wolseley petrol engine
  • 1 × electric motor
Speed:
  • 11 knots (20 km/h; 13 mph) surfaced
  • 7 knots (13 km/h; 8.1 mph) submerged
Range: 500 nautical miles (930 km; 580 mi) at 10 kn (19 km/h; 12 mph) surfaced
Complement: 2 officers and 9 ratings
Armament: 2 × 18-inch (45 cm) torpedo tubes

Design and description

A7 was a member of the first British class of submarines, although slightly larger, faster and more heavily armed than the lead ship, HMS A1. The submarine had a length of 105 feet 1 inch (32.0 m) overall, a beam of 12 feet 9 inches (3.9 m) and a mean draft of 10 feet 8 inches (3.3 m). They displaced 190 long tons (190 t) on the surface and 206 long tons (209 t) submerged. The A-class submarines had a crew of 2 officers and 11 ratings.[1]

For surface running, the boats were powered by a single 16-cylinder 550-brake-horsepower (410 kW) Wolseley petrol engine that drove one propeller shaft. When submerged the propeller was driven by a 150-horsepower (112 kW) electric motor. They could reach 11 knots (20 km/h; 13 mph) on the surface and 7 knots (13 km/h; 8.1 mph) underwater.[1] On the surface, A7 had a range of 500 nautical miles (930 km; 580 mi) at 10 knots (19 km/h; 12 mph); submerged the boat had a range of 30 nautical miles (56 km; 35 mi) at 5 knots (9.3 km/h; 5.8 mph).[2]

The boats were armed with two 18-inch (45 cm) torpedo tubes in the bow. They could carry a pair of reload torpedoes, but generally did not as doing so that they had to compensate for their weight by an equivalent weight of fuel.[3]

Construction and career

A7 was ordered as part of the 1903–04 Naval Programme from at Vickers.[4] She was laid down at their shipyard in Barrow-in-Furness on 1 September 1903, launched on 21 January 1905 and completed on 13 April.[2] She sank in Whitsand Bay, Cornwall on 16 January 1914 with the loss of her crew whilst carrying out dummy torpedo attacks on Pygmy in conjunction with submarine A9. A disturbance in the water was seen which thought to be caused by the crew of A7 attempting to blow water from her ballast tanks in a desperate attempt to reach the surface.[5] The location was marked with a buoy and Pygmy returned to Plymouth Sound to report on the disaster. Pygmy returned to the site in the afternoon but was unable to locate the buoy as the weather had deteriorated. It then took five days to relocate the submarine, she was found in 121 ft (37 m) depth with 20 ft (6.1 m) of her stern buried in the muddy seabed and with her bow 33 ft (10 m) off the bottom, raised at an angle of 30°.[5] Several attempts were made to salvage her over the next month by attaching a hawser to the towing eye on the bow or wrapping steel hawsers around her hull, but her stern was too deeply embedded in the mud and the hawsers parted without pulling her out. She lies today where she sank, buried up to her waterline in a flat, mud seabed in about 121 ft (37 m) of water. In 2001, she was declared as one of 16 wrecks in British waters designated as "Controlled Sites" under the Protection of Military Remains Act by the British Government and which cannot be dived without special permission.

In 2014 the SHIPS Project team in Plymouth completed an archaeological investigation of the A7 submarine, having been granted a licence by the UK Ministry of Defence.[6]

Notes
  1. Gardiner & Gray, p. 86
  2. Akermann, p. 120
  3. Harrison, Chapter 27
  4. Harrison, Chapter 3
  5. Holt, Chapter 7
  6. Holt, Chapter 1

References
  • Akermann, Paul (2002). Encyclopaedia of British Submarines 1901–1955 (reprint of the 1989 ed.). Penzance, Cornwall: Periscope Publishing. ISBN 1-904381-05-7.
  • Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8.
  • Gardiner, Robert & Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships: 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN 0-85177-245-5.
  • Harrison, A. N. (January 1979). "The Development of HM Submarines From Holland No. 1 (1901) to Porpoise (1930) (BR3043)". Submariners Association: Barrow in Furness Branch. Archived from the original on 19 May 2015. Retrieved 19 August 2015.
  • Innes McCartney (2002). Lost Patrols: Submarine Wrecks of the English Channel.
  • Holt, Peter (2015). HM Submarine A7, An Archaeological Assessment, BAR British Series no. 613, Oxford,. ISBN 978-1407-31374-0.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.