HMS L56 was a late-model L-class submarine built for the Royal Navy during the First World War. The boat was not completed before the end of the war and was sold for scrap in 1938.
L52 and its successors were modified to maximise the number of 21-inch (53.3 cm) torpedoes carried in the bow. The submarine had a length of 235 feet (71.6 m) overall, a beam of 23 feet 6 inches (7.2 m) and a mean draft of 13 feet 2 inches (4.0 m).[1] They displaced 960 long tons (980 t) on the surface and 1,150 long tons (1,170 t) submerged. The L-class submarines had a crew of 44 officers and ratings.[2] They had a diving depth of 150 feet (45.7 m).[3]
For surface running, the boats were powered by two 12-cylinder Vickers[4] 1,200-brake-horsepower (895 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor. They could reach 17 knots (31 km/h; 20 mph) on the surface and 10.5 knots (19.4 km/h; 12.1 mph) underwater. On the surface, the L class had a range of 4,200 nautical miles (7,800 km; 4,800 mi) at 10 knots (19 km/h; 12 mph).[1]
The boats were armed with six 21-inch torpedo tubes in the bow. They carried eight reload torpedoes for a grand total of a dozen torpedoes.[5] They were also armed with two 4-inch (102 mm) deck guns.[2]
HMS L56 was laid down on 16 October 1917 by Fairfield Shipbuilding and Engineering Company at their Govan shipyard, launched on 29 May 1919, and completed on 3 September 1919. The boat was sold for scrap on 25 March 1938.