:HMS X1

The X1{{'}}s {{convert|1|in|adj=on}} thick pressure hull was {{convert|19|ft|7.5|in|1}} in diameter amidships, and was divided into 10 watertight compartments. This was almost completely surrounded by her external hull, which also contained the main ballast tanks and most of her fuel. Her intended maximum diving depth was {{convert|500|ft}}, but was reduced to {{convert|350|ft}} once in service.Brown 1982, p. 232

X1 carried four QF 5.2 inch Mk I guns{{Cite web |url=http://www.navweaps.com/Weapons/WNBR_52-42_mk1.php |title=Britain 5.2"/42 (13.2 cm) Mark I |website=NavWeaps |access-date=21 April 2021 |archive-date=21 April 2021 |archive-url=https://web.archive.org/web/20210421113604/http://www.navweaps.com/Weapons/WNBR_52-42_mk1.php |url-status=live }} in twin unarmoured turrets, one forward and one aft of the conning tower. They had a range of about {{convert|16000|yd}}. A circular trunk ran from each mounting to the magazine in the pressure hull which contained 100 rounds per gun. A working chamber which was {{convert|10|ft}} in diameter encircled the trunk between the pressure hull and the gun mount. Her ammunition hoists were problematic and could not sustain the desired rate of fire of six rounds per gun per minute. Special ballast tanks were used to compensate for the loss of weight as ammunition was fired. Working and control of the guns required 58 men.Akermann 2002, p. 218 The fire-control tower was in the middle of the conning tower and had a top section that could be raised {{convert|2|ft}} when in use. The upper control room was between the tower and the pressure hull. Just aft of the control room was the rangefinding room, with a {{convert|9|ft|adj=on}} rangefinder on the bridge that could be raised {{convert|8|ft}}.

Her six bow tubes for British 21 inch torpedo came from a cancelled L-class submarine and she was provided with one reload for each tube. It took 24 minutes to reload them all because space in the torpedo room was restricted.

The main engines were two 8-cylinder Admiralty diesel engines with a total output of {{convert|3000|bhp|kW|lk=on}}. Two auxiliary {{convert|1200|hp|kW|adj=on}} MAN diesel engines taken from the German submarine U-126 were installed for battery-charging purposes. For underwater propulsion, two GEC electric motors of {{convert|1000|hp|kW}} each were fitted. It was hoped to achieve over {{convert|8000|hp|kW}} using both diesels and electric motors together, but the highest power achieved (during a full power trial in March 1926) was {{convert|7135|hp|kW}}. She had three groups of batteries, each with 110 cells weighing a total of {{convert|70|LT|t}}.Brown 1982, p. 233

In theory she could make {{convert|19.5|kn|lk=in}} on the surface, and at economical speed she had a greater range than normal cruisers, but both sets of diesel engines suffered from continual mechanical problems that reduced her speed and range. The X1{{'}}s average diving time to periscope depth was 2 minutes 20 seconds. Her handling underwater was considered superior to other submarines of the period.Akermann 2002, p. 220

After X1 was commissioned in December 1925 and accepted in April 1926 she made a voyage to Gibraltar after which her main engine drive wheels were found to be damaged. After repairs she was sent to the Mediterranean Sea. Her starboard camshaft driveshaft broke during a full-power run in January 1928 and a new set of gears was needed, but after refitting at Malta her port camshaft driveshaft broke in the same place in April 1928. By 1930 her commanding officer reported "internal arrangements not very satisfactory because of overcrowding with auxiliary machinery, accommodation is cramped, ventilation poor and the ship suffers from humidity, diving arrangements good." Both the main and auxiliary engines were troublesome and she spent most of her time under repair, before being laid up. X1 was placed in reserve after 1930, before she was finally scrapped at Pembroke on 12 December 1936.

• British M-class submarine — an earlier attempt at a large gun-armed submarine
• SM U-139 - U-139 class (Projekt 46); one of three German First World War submarine cruisers
• Surcouf — a similar French large gun-armed submarine

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• {{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}}
• {{cite book|last=Brown|first=David K.|chapter=X1-Cruiser Submarine|editor=John Roberts|publisher=Conway Maritime Press|location=London|date=1982|title=Warship|volume=VI|pages=232–233|isbn=0-85177-265-X|author-link=David K. Brown}}

• {{cite book | last = Branfill-Cook | first = Roger | title = X.1 The Royal Navy's Mystery Submarine | publisher = Seaforth Publishing | year = 2012 | location =Barnsley, UK | isbn = 978-1-84832-161-8}}
• {{cite book | last = Compton-Hall | first = Richard | title = Submarine Warfare, Monsters and Midgets | publisher = Blandford Press | year = 1985 | location =Poole, UK | isbn = 0-7137-1389-5}}

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Category:Submarines of the Royal Navy

Category:1923 ships

Category:Surface-underwater ships