Editing HMS J7 (section)

==Design and construction==
{{Main|J-class submarine}}
The J class was designed by the Royal Navy in response to reported German submarines with surface speeds over {{convert|18|kn}}.<ref name=Bastock86>Bastock, ''Australia's Ships of War'', p. 86</ref> 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.<ref name=Bastock86/> Each submarine was {{convert|275|ft}} in length overall, with a beam of {{convert|22|ft}}, and a draught of {{convert|14|ft}}.<ref name=Bastock86/> The propulsion system was built around three propeller shafts; the J-class were the only triple-screwed submarines ever built by the British.<ref name=Bastock86/> Propulsion came from three 12-cylinder diesel motors when on the surface, and electric motors when submerged.<ref name=Bastock86/> Top speed was {{convert|19|kn}} on the surface (the fastest submarines in the world at the time of construction), and {{convert|9.5|kn}} underwater.<ref name=Bastock86/> Range was {{convert|4,000|nmi}} at {{convert|12|kn}}.<ref name=Bastock86/>

Armament consisted of six [[British 18 inch torpedo|18 inch (450 mm)]] torpedo tubes (four forward, one on each beam), plus a 4-inch deck gun.<ref name=Bastock86/> Originally, the gun was mounted on a [[Breastwork (fortification)|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]].<ref name=Bastock86/> The conning tower on ''J7'' was sited {{convert|60|ft|m}} further back than her sister boats, as the control room was located behind the machinery spaces.<ref name=Bastock86/><ref name=tall>{{cite book |title=HM Submarines in Camera An Illustrated History of British Submarines |last=Tall |first=J.J |author2=Paul Kemp |year=1996 |publisher=Sutton Publishing |isbn=0-7509-0875-0 |page=54}}</ref> 44 personnel were aboard.<ref name=Bastock86/>

''J7'' was built by [[HMNB Devonport|HM Dockyard Devonport]] in [[Plymouth]] and launched on 12 February 1917.<ref>{{Cite web |title=HMAS J7 |publisher=Royal Australian Navy |url=http://www.navy.gov.au/hmas-j7 |accessdate=2011-03-13 }}</ref>