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HMAS J7 (AWM H12461).jpg
Career (United Kingdom)
Name: HMS J7
Builder: HM Dockyard, Devonport
Launched: 12 February 1917
Fate: Transferred to Australia, 25 March 1919
Career (Australia)
Name: HMAS J3
Acquired: 25 March 1919
Decommissioned: 12 July 1922
Fate: Sunk 4 June 1926
General characteristics
Class & type: British J class submarine
Displacement: 1,210 long tons (1,230 t) (surfaced)
1,760 long tons (1,790 t) (submerged)
Length: 275 ft (84 m)
Beam: 22 ft (6.7 m)
Draught: 14 ft (4.3 m)
Propulsion: Three shafts
Surfaced: three 12-cylinder diesel engines
Submerged: battery-driven electric motors
Speed: 19 kn (35 km/h; 22 mph) (surfaced)
9.5 kn (17.6 km/h; 10.9 mph) (submerged)
Range: 4,000 nmi (7,400 km; 4,600 mi) at 12 kn (22 km/h; 14 mph)
Test depth: 300 ft (91 m) max[citation needed]
Complement: 44 personnel
Armament: six 18 in (457 mm) torpedo tubes
(four bow, two beam)
one 4 in (102 mm) gun

HMS J7 (later HMAS J7) was a J-class submarine operated by the Royal Navy and the Royal Australian Navy.

Design and construction[edit]

Main article: J-class submarine

The J class was designed by the Royal Navy in response to reported German submarines with surface speeds over 18 knots (33 km/h; 21 mph).[1] 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.[1] Each submarine was 275 feet (84 m) in length overall, with a beam of 22 feet (6.7 m), and a draught of 14 feet (4.3 m).[1] The propulsion system was built around three propeller shafts; the J-class were the only triple-screwed submarines ever built by the British.[1] Propulsion came from three 12-cylinder diesel motors when on the surface, and electric motors when submerged.[1] Top speed was 19 knots (35 km/h; 22 mph) on the surface (the fastest submarines in the world at the time of construction), and 9.5 knots (17.6 km/h; 10.9 mph) underwater.[1] Range was 4,000 nautical miles (7,400 km; 4,600 mi) at 12 knots (22 km/h; 14 mph).[1]

Armament consisted of six 18-inch torpedo tubes (four forward, one on each beam), plus a 4-inch deck gun. [1] 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. [1] The conning tower on J7 was sited 60 feet (18 m) further back than her sister boats, as the control room was located behind the machinery spaces.[1][2] 44 personnel were aboard.[1]

J7 was built by HM Dockyard Devonport in Plymouth and launched on 12 February 1917.[3]

Operational history[edit]

After the war, the British Admiralty decided that the best way to protect the Pacific region was with a force of submarines and cruisers.[1] To this end, the offered the six surviving submarines of the J-class to the Royal Australian Navy as gifts.[1] 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 Sydney and Brisbane, and the tender Platypus.[1] The flotilla reached Thursday Island on 29 June, and Sydney on 10 July.[1] Because of the submarines' condition after the long voyage, they were immediately taken out of service for refits.[1]

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.[1]


J7 paid off on 12 July 1922, was sold on 26 February 1924 and her hulk scuttled on 4 June 1926. Her wreck sits at the bottom of the mini harbour of the Sandringham yacht club in Port Phillip.[4]


  1. ^ a b c d e f g h i j k l m n o p q Bastock, Australia's Ships of War, p. 86
  2. ^ Tall, J.J; Paul Kemp (1996). HM Submarines in Camera An Illustrated History of British Submarines. Sutton Publishing. p. 54. ISBN 0-7509-0875-0. 
  3. ^ "HMAS J7". Royal Australian Navy. Retrieved 2011-03-13. 
  4. ^ Milowka, Agnes. "Victoria's J Class Submarines". Archived from the original on 2011-03-13. 


External links[edit]

Coordinates: 37°56′36″S 144°59′41″E / 37.943381°S 144.99471°E / -37.943381; 144.99471