HMS K7 was a K class submarine built by HM Dockyard, Devonport. She was laid down on 8 November 1915 and commissioned in July 1917.
K7 was the only one of the disastrous K class to engage with an enemy; on 16 June 1917 she fired a salvo of torpedoes at the U-boat U-95 and scored a direct hit. However, the torpedo failed to explode with what has been described as typical "K" luck; K-7 escaped retaliation by steaming away at speed.[1]
K7 was involved in an accident with the 4th Light Cruiser Squadron. She was also involved in the catastrophic series of accidents during a night exercise that came to be known sarcastically as the Battle of May Island; K7 was damaged by running over the sinking K4. K7 was sold on 9 September 1921 at Sunderland.
Design
K7 displaced 1,800 long tons (1,800 t) when at the surface and 2,600 long tons (2,600 t) while submerged.[2] It had a total length of 338 feet (103 m), a beam of 26 feet 6 inches (8.08 m), and a draught of 20 ft 11 in (6.38 m).[3] The submarine was powered by two oil-fired Yarrow Shipbuilders boilers supplying one geared Brown-Curtis or Parsons steam turbine that developed 10,500 ship horsepower (7,800 kW) to drive two 7 ft 6 in (2.29 m) screws. Submerged power came from four electric motors each producing 350 to 360 horsepower (260 to 270 kW).[3] It also had an 800 hp (600 kW) diesel engine to be used when steam was being raised, or instead of raising steam.[4]
The submarine had a maximum surface speed of 24 kn (44 km/h) and a submerged speed of 9 to 9.5 kn (16.7 to 17.6 km/h).[3][5] It could operate at depths of 150 ft (46 m) at 2 kn (3.7 km/h) for 80 nmi (150 km).[2]K7 was armed with ten 18-inch (460 mm) torpedo tubes, two 4-inch (100 mm) deck guns, and a 3-inch (76 mm) anti-aircraft gun.[3] Its torpedo tubes were fitted to the bows, the midship section, and two were mounted on the deck.[2] Its complement was fifty-nine crew members.[5]
