HMS K12 was a K class submarine built by Armstrong Whitworth, Newcastle upon Tyne. She was laid down in October 1915 and commissioned in August 1917. K12 took part in the Battle of May Island, surviving the disastrous exercise. K12 collided with HMS K2 in 1924; K2 smashed a hole in the forward casing of K12 while K2 buckled her bows for about six feet. K12 was scrapped in 1926 in Charlestown.

Design

K12 displaced 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 supplying one geared Brown-Curtis or Parsons steam turbine; this developed 10,500 ship horsepower (7,800 kW) to drive two 7 ft screws. Submerged power came from four electric motors each producing 350 to 360 hp. It was also had an 800 hp diesel engine 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 armed with ten 18 in torpedo tubes, two 4 in deck guns, and a 3 in anti-aircraft gun. 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.