HMS J7 (later HMAS J7) was a J-class

submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...

operated by the

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...

and the

Royal Australian Navy The Royal Australian Navy (RAN) is the principal naval force of the Australian Defence Force (ADF). The professional head of the RAN is Chief of Navy (CN) Vice Admiral Mark Hammond AM, RAN. CN is also jointly responsible to the Minister of ...

Design and construction

The J class was designed by the Royal Navy in response to reported German submarines with surface speeds over .Bastock, ''Australia's Ships of War'', p. 86 The submarines had a displacement of 1,210 tons surfaced, but ''J7'' had a lighter submerged displacement than her sister boats, at 1,760 tons. Each submarine was in length overall, with a beam of , and a draught of . The propulsion system was built around three propeller shafts; the J-class were the only triple-screwed submarines ever built by the British. Propulsion came from three 12-cylinder diesel motors when on the surface, and electric motors when submerged. Top speed was on the surface (the fastest submarines in the world at the time of construction), and underwater. Range was at . Armament consisted of six 18 inch (450 mm) torpedo tubes (four forward, one on each beam), plus a 4-inch deck gun. Originally, the gun was mounted on a breastwork fitted forward of the conning tower, but the breastwork was later extended to the bow and merged into the hull for streamlining, and the gun was relocated to a platform fitted to the front of the conning tower. The conning tower on ''J7'' was sited further back than her sister boats, as the control room was located behind the machinery spaces. 44 personnel were aboard. ''J7'' was built by HM Dockyard Devonport in

Plymouth Plymouth () is a port city and unitary authority in South West England. It is located on the south coast of Devon, approximately south-west of Exeter and south-west of London. It is bordered by Cornwall to the west and south-west. Plymouth ...

and launched on 12 February 1917.

Operational history

After the war, the British Admiralty decided that the best way to protect the Pacific region was with a force of submarines and cruisers. To this end, they offered the six surviving submarines of the J-class to the

as gifts. ''J1'' and her sisters were commissioned into the RAN in April 1919, and sailed for Australia on 9 April, in the company of the cruisers and , and the tender . The flotilla reached Thursday Island on 29 June, and Sydney on 10 July. Because of the submarines' condition after the long voyage, they were immediately taken out of service for refits. HMAS J7 Submarine Sandringham Yacht Club 600 1662

HMAS J7 Submarine Sandringham Yacht Club 600 1662

By the time ''J7'' was returned to service in June 1922, the cost of maintaining the boats and deteriorating economic conditions saw the six submarines decommissioned and marked for disposal.

Fate

''J7'' was paid off on 12 July 1922, and was sold on 26 February 1924. The hulk was scuttled in 1930, for use as a

breakwater Breakwater may refer to: * Breakwater (structure), a structure for protecting a beach or harbour Places * Breakwater, Victoria, a suburb of Geelong, Victoria, Australia * Breakwater Island Breakwater Island () is a small island in the Palme ...

at the Sandringham yacht club in

Port Phillip Port Phillip ( Kulin: ''Narm-Narm'') or Port Phillip Bay is a horsehead-shaped enclosed bay on the central coast of southern Victoria, Australia. The bay opens into the Bass Strait via a short, narrow channel known as The Rip, and is com ...

. Some years later a stone marina was constructed around the wreck, which was left in situ and visible, being too expensive to remove, where it continues to deteriorate.

Citations

References

External links

Map of Sandringham yacht club marina
{{DEFAULTSORT:J7 British J-class submarines Ships built in Plymouth, Devon 1917 ships World War I submarines of the United Kingdom Scuttled vessels of Australia Royal Navy ship names Shipwrecks of Victoria (Australia)