HMS L23

L9 and its successors were enlarged to accommodate 21-inch (53.3 cm) torpedoes and more fuel. The submarine had a length of 238 feet 7 inches (72.7 m) overall, a beam of 23 feet 6 inches (7.2 m) and a mean draft of 13 feet 3 inches (4.0 m).[1] They displaced 914 long tons (929 t) on the surface and 1,089 long tons (1,106 t) submerged. The L-class submarines had a crew of 35 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.[1] 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 3,800 nautical miles (7,000 km; 4,400 mi) at 10 knots (19 km/h; 12 mph).[3]

The boats were armed with four 21-inch torpedo tubes in the bow and two 18-inch (45 cm) in broadside mounts. They carried four reload torpedoes for the 21-inch tubes for a grand total of ten torpedoes of all sizes.[5] They were also armed with a 4-inch (102 mm) deck gun.[2]

HMS L23 was laid down on 26 July 1917 by Vickers at their Barrow-in-Furness shipyard, launched on 1 July 1919. The boat was then towed to Chatham Royal Dockyard and finished on 31 October 1924. She served on the China Station in the 1920s. HMS L23 survived a heavy depth charge attack by two German destroyers in February 1940. An oil leak occurred, which lead the Germans to believe that the submarine was destroyed. L23 was sold for scrap in May 1946.

• Akermann, Paul (2002). Encyclopaedia of British Submarines 1901–1955 (reprint of the 1989 ed.). Penzance, Cornwall: Periscope Publishing. ISBN 1-904381-05-7.
• Colledge, J. J.; Warlow, Ben (2006) [1969]. Ships of the Royal Navy: The Complete Record of all Fighting Ships of the Royal Navy (Rev. ed.). London: Chatham Publishing. ISBN 978-1-86176-281-8.
• Gardiner, Robert & Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships 1906–1921. Annapolis, Maryland: Naval Institute Press. ISBN 0-85177-245-5.
• Harrison, A. N. (January 1979). "The Development of HM Submarines From Holland No. 1 (1901) to Porpoise (1930) (BR3043)". RN Subs. Retrieved 27 September 2022.