HMS A7 was an 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.

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, . The submarine had a length of overall, a beam of and a mean draft of . They displaced on the surface and submerged. The A-class submarines had a crew of 2 officers and 9 ratings.

For surface running, the boats were powered by a single 16-cylinder Wolseley petrol engine that drove one propeller shaft. When submerged the propeller was driven by a electric motor. They could reach on the surface and underwater.

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.

Construction and career

A7 was ordered as part of the 1903–04 Naval Programme from Vickers. 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. 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 depth with of her stern buried in the muddy seabed and with her bow off the bottom, raised at an angle of 30°.

Notes

References

  • MaritimeQuest HMS A-7 Pages
  • SHIPS Project
  • HMS A-7 Roll of Honour
  • SI 2008/950 Designation under the Protection of Military Remains Act 1986
  • 'Submarine losses 1904 to present day' - Royal Navy Submarine Museum
  • The A7 Project - an archaeological investigation of HM submarine A7