HMS J7

The J class was designed by the Royal Navy in response to reported German submarines with surface speeds over . 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. 44 personnel were aboard. ==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 Royal Australian Navy 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. 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 at the Sandringham Yacht Club in Port Phillip. 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==