{{Use dmy dates|date=December 2016}} {{Use British English|date=December 2016}} {{Infobox ship |section1={{Infobox ship/image |image= Submarine Flotilla 1933 at Gosport.jpg |image_caption=''L20'' and three other L–class boats at Gosport (1933) }}

|section2={{Infobox ship/career |hide_header= |country= United Kingdom |flag= {{shipboxflag|United Kingdom|naval}} |name= HMS ''L20'' |namesake= |ordered= |builder=[[Vickers Limited]], [[Barrow-in-Furness]] |laid_down= 26 July 1917 |launched= 23 September 1918 |acquired= |commissioned= 28 January 1919 |decommissioned= |in_service= |out_of_service= |struck= |reinstated= |homeport= |motto= |nickname= |honours= |fate= Sold for scrapping, 7 January 1935 |notes= }}

|section3={{Infobox ship/characteristics |hide_header= |header_caption= |class=[[British L class submarine|L-class submarine]] |displacement=*{{convert|914|LT|t|abbr=on}} surfaced *{{convert|1089|LT|t|abbr=on}} submerged |length={{convert|238|ft|7|in|m|1|abbr=on}} |beam={{convert|23|ft|6|in|m|1|abbr=on}} |draught={{convert|13|ft|3|in|1|abbr=on}} |power=*{{convert|2400|bhp|kW|lk=in|abbr=on}} (diesel) *{{convert|1600|hp|kW|abbr=on}} (electric) |propulsion=*2 × [[diesel engine]]s *2 × [[electric motor]]s |speed=*{{convert|17|kn|abbr=on|lk=in}} surfaced *{{convert|10.5|kn|abbr=on}} submerged |range={{convert|3800|nmi|abbr=on|lk=in}} at {{convert|10|kn|abbr=on}} on the surface |test_depth={{convert|150|ft|1}} |complement=38 |armament=*4 × bow [[British 21-inch torpedo|{{convert|21|in|mm|0|abbr=on}}]] [[torpedo tube]]s *2 × beam [[British 18 inch torpedo|{{convert|18|in|mm|0|abbr=on}}]] torpedo tubes *1 × [[QF 4 inch naval gun Mk IV, XII, XXII|4-inch]] [[deck gun]] |notes= }} }} '''HMS ''L20''''' was a [[British L class submarine|L-class submarine]] built for the Royal Navy during World War I. The boat was not completed before the end of the war and was sold for [[ship breaking|scrap]] in 1935.

==Design and description== ''L9'' and its successors were enlarged to accommodate [[British 21 inch torpedo|21-inch (53.3&nbsp;cm)]] torpedoes and more fuel. The submarine had a length of {{convert|238|ft|7|in|m|1}} [[length overall|overall]], a [[beam (nautical)|beam]] of {{convert|23|ft|6|in|m|1}} and a mean [[draft (ship)|draft]] of {{convert|13|ft|3|in|m|1}}.<ref name=gg9>Gardiner & Gray, p. 93</ref> They [[displacement (ship)|displaced]] {{convert|914|LT|t}} on the surface and {{convert|1089|LT|t}} submerged. The L-class submarines had a crew of 38 officers and [[naval rating|ratings]].<ref name=a5>Akermann, p. 165</ref> They had a diving depth of {{convert|150|ft|1}}.<ref name=h11/>

For surface running, the boats were powered by two 12-cylinder [[Vickers]]<ref>Harrison, Chapter 25</ref> {{convert|1200|bhp|lk=in|0|adj=on}} [[diesel engine]]s, each driving one [[propeller shaft]]. When submerged each propeller was driven by a {{convert|600|hp|0|adj=on}} [[electric motor]].<ref name=gg9/> They could reach {{convert|17|kn|lk=in}} on the surface and {{convert|10.5|kn}} underwater. On the surface, the L class had a range of {{convert|3800|nmi|lk=in}} at {{convert|10|kn}}.<ref name=h11>Harrison, Chapter 11</ref>

The boats were armed with four 21-inch [[torpedo tube]]s in the bow and two [[British 18 inch torpedo|18-inch (45&nbsp;cm)]] in broadside mounts. They carried four reload torpedoes for the 21-inch tubes for a grand total of ten torpedoes of all sizes.<ref>Harrison, Chapter 27</ref> They were also armed with a {{convert|4|in|mm|adj=on|0}} [[deck gun]].<ref name=a5/>

==Construction and career== HMS ''L20'' was [[laid down]] on 26 July 1917 by [[Vickers]] at their [[Barrow-in-Furness]] [[shipyard]], [[Ship naming and launching|launched]] on 23 September 1918, and completed on 28 January 1919. ''L20'' was assigned to the [[4th Submarine Flotilla]] and {{HMS|Titania}} in 1919 and sailed to [[Hong Kong]], arriving on 14 April 1920. She was transferred to the reserve flotilla in 1923 in Hong Kong. She was sold to [[John Cashmore Ltd]] on 7 January 1935 for breaking up at [[Newport, Wales|Newport]]. Her bell is in the [[Royal Navy Submarine Museum]]. <gallery widths=300 heights=200> File:L20 Bias Bay Feb 1929.jpg|L20 in Bias Bay (Daya Bay), China, May 1929 (Thomas C. Wilding collection) File:L20 Yangtse Kiang.jpg|L20 on Yangtze River (written Yangtse Kiang) c. 1929 (Thomas C Wilding collection) </gallery>

==Notes== {{reflist|30em}}

==References== * {{cite book|last=Akermann|first=Paul|title=Encyclopaedia of British Submarines 1901–1955|edition=reprint of the 1989|year=2002|publisher=Periscope Publishing|location=Penzance, Cornwall|isbn=1-904381-05-7}} * {{Colledge: Ships RN|year=2006}} * {{cite book |editor1-last=Gardiner|editor1-first=Robert|editor2-last=Gray|editor2-first=Randal|title=Conway's All the World's Fighting Ships 1906–1921|year=1985|location=Annapolis, Maryland|publisher=Naval Institute Press|isbn=0-85177-245-5|name-list-style=amp}} * {{cite web|url=http://rnsubs.co.uk/dits-bits/br-3043.html|title=The Development of HM Submarines From Holland No. 1 (1901) to Porpoise (1930) (BR3043)|last=Harrison|first=A. N.|date=January 1979|publisher=RN Subs|access-date=27 September 2022}}

{{British L class submarine}}

{{DEFAULTSORT:L20}} [[Category:British L-class submarines]] [[Category:Ships built in Barrow-in-Furness]] [[Category:1918 ships]] [[Category:World War I submarines of the United Kingdom]] [[Category:Royal Navy ship names]]