The L-class boats were enlarged and improved versions of the preceding E class. The submarine had a length of 231feet overall, a beam of 23feet and a mean draught of 13feet. They displaced 891LT on the surface and 1074LT submerged. The L-class submarines had a crew of 35 officers and ratings.[1]
For surface running, the boats were powered by two 12-cylinder Vickers[2] 12000NaN0 diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600hp electric motor.[1] They could reach 17kn on the surface and underwater.[3] On the surface, the L class had a range of 3200nmi at .[1]
The boats were armed with a total of six 18inches torpedo tubes. Four of these were in the bow and the remaining pair in broadside mounts. They carried 10 reload torpedoes, all for the bow tubes.[4] L1 was initially fitted with a 3inches anti-aircraft gun, but this was later replaced by a 4adj=onNaNadj=on deck gun.[5]
Originally laid down by Vickers, Barrow, as E-class submarine E57 on 18 May 1916, she and sister ship incorporated enough changes that they were renamed as the first pair of boats of a newly designated L class. L1 was launched 10 May 1917, and commissioned on 10 November 1917.
She sailed with the Submarine Depot Ship HMS Ambrose (1903) to Hong Kong in 1919 as part of the 4th Submarine Flotilla, arriving there in January 1920. L1 was placed in the reserve flotilla in 1923 in Hong Kong. She was then sold to John Cashmore Ltd in March 1930 for scrapping. While being towed to Newport she broke free and was stranded at Penanwell Cove, near Porth Nanven in Cornwall. She was scrapped where she lay. Some metal remains can still be seen there on low spring tides.[6]