The K class submarine

The K class submarines were a class of steam-propelled submarines of the Royal Navy designed in 1913. Intended as large, fast vessels with the endurance and speed to operate with the battle fleet.
In 1913, a design outline was prepared for a new class of submarine which could operate with the surface fleet, sweeping ahead of it in a fleet action. Due to the superior size and power of the British Grand Fleet over the German High Seas Fleet it was intended that the submarines would get around the back of the enemy fleet and ambush it as it retreated.
The double hull design had a reserve buoyancy of 32.5 percent. Although powered on the surface by oil-fired steam turbines, they were also equipped with an 800 hp (0.6 MW) diesel generator to charge the batteries and provide limited propulsive power in the event of problems with the boilers.
This pushed the displacement up to 1,980 tons on the surface, 2,566 tons submerged. They were equipped with four 18 inch (460 mm) torpedo tubes at the bow, two on either beam and another pair in a swivel mounting on the superstructure for night use. The swivel pair were later removed because they were prone to damage in rough seas. The K-class submarines were fitted with a proper deckhouse, built over and around the conning tower, which gave the crew much better protection than the canvas screens fitted in previous Royal Navy submarines.
he great size of the boats (compared to their predecessors) led to control and depth keeping problems particularly as efficient telemotor controls had not yet been developed. This was made worse by the estimated maximum diving depth of 200 ft (60 m) being much less than their overall length. Even a 10 degree angle on the 339 ft (103 m) long hull would cause a 59 ft (18 m) difference in depth of the bow and stern, and 30 degrees would produce 170 ft (50 m) which meant that while the stern would almost be on the surface, the bow would almost be at its maximum safe depth. The submarines were made more dangerous because the eight internal bulkheads were designed and tested during development to stand a pressure equivalent to only 70 ft (20 m), risking their collapse if the hull was compromised at a depth below this figure.
Most were scrapped between 1921 and 1926 but K26 survived until 1931, being broken up because her displacement exceeded the limits for submarine displacement in the London Naval Treaty of 1930. K18, K19 and K20 became the new M class submarines. K21, K23, K24, K25, K27 and K28 were cancelled. Although the concept of a submarine fast enough to operate with a battle fleet eventually fell out of favour, it was still an important consideration in the design of the Thames class in the late 1920s.

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