HMS K11 was a K class submarine built by Armstrong Whitworth, Newcastle upon Tyne. K11 was laid down in October 1915, and commissioned in February 1917. It had a complement of 59 crew members. In 1917, K11 was damaged by fire during a North Sea patrol. She was forced to surface and was towed by a destroyer. K11 was part of the disastrous Battle of May Island exercise. She was forced to take avoiding action to avoid HMS K14, but survived the exercise. K11 was sold on 4 November 1921.

Design

Like all British K-class submarines, K9 had a displacement of 1800 LT when at the surface and 2600 LT while submerged. It had a total length of 338 ft, a beam of 26 ft, and a draught of 20 ft. The submarine was powered by two oil-fired Yarrow Shipbuilders boilers and one geared Brown-Curtis or Parsons steam turbine; this developed 10,500 ship horsepower (7,800 kW) to drive two 7 ft screws. It also contained four electric motors each producing 350 to 360 hp. It was also fitted with a diesel engine providing 800 hp to be used when steam was being raised, or instead of raising steam. The submarine had a maximum surface speed of 24 kn and a submerged speed of 9 to 9.5 kn. It could operate at depths of 150 ft at 2 kn for 80 nmi. K9 was fitted with a 3 in anti-aircraft gun, ten 18 in torpedo tubes, and two 4 in deck guns. Its torpedo tubes were fitted to the bows, the midship section, and two were mounted on the deck. Its complement was fifty-nine crew members.