HM Submarine ''X1'' was a British

submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...

of the interwar period. Conceived and designed as a submersible

commerce raider Commerce raiding (french: guerre de course, "war of the chase"; german: Handelskrieg, "trade war") is a form of naval warfare used to destroy or disrupt logistics of the enemy on the open sea by attacking its merchant shipping, rather than enga ...

for the

Royal Navy The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...

; at the time of her launching she was the largest submarine in the world. For Britain, the idea of a submarine cruiser had been proposed as early as 1915, but the type was not put into practice until after the end of

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

in 1918. ''X1'' was

laid down Laying the keel or laying down is the formal recognition of the start of a ship's construction. It is often marked with a ceremony attended by dignitaries from the shipbuilding company and the ultimate owners of the ship. Keel laying is one o ...

on 2 November 1921 at HM Dockyard, Chatham and completed on 23 September 1925 with commissioning following in December 1925. The 1922

Washington Naval Treaty The Washington Naval Treaty, also known as the Five-Power Treaty, was a treaty signed during 1922 among the major Allies of World War I, which agreed to prevent an arms race by limiting naval construction. It was negotiated at the Washington Nav ...

, of which Britain was a signatory, did not ban submarines but it did ban their use against merchant ships, which was ''X1''s unacknowledged purpose; its armament had been designed to successfully engage the classes of vessels likely to be escorting convoys, such as

destroyers In navy, naval terminology, a destroyer is a fast, manoeuvrable, long-endurance warship intended to escort larger vessels in a Naval fleet, fleet, convoy or Carrier battle group, battle group and defend them against powerful short range attack ...

and

frigates A frigate () is a type of warship. In different eras, the roles and capabilities of ships classified as frigates have varied somewhat. The name frigate in the 17th to early 18th centuries was given to any full-rigged ship built for speed and ...

. Therefore, a certain amount of secrecy surrounded ''X1'', the government even going to the lengths of taking a national newspaper to court over its pictures of the new submarine following her launch, all copies of the paper being seized.

Description

The ''X1''s thick

pressure hull A submarine hull has two major components, the ''light hull'' and the ''pressure hull''. The light hull (''casing'' in British usage) of a submarine is the outer non-watertight hull which provides a hydrodynamically efficient shape. The pressure ...

was in diameter amidships, and was divided into 10

watertight compartment A compartment is a portion of the space within a ship defined vertically between decks and horizontally between bulkheads. It is analogous to a room within a building, and may provide watertight subdivision of the ship's hull important in retaini ...

s. This was almost completely surrounded by her external hull, which also contained the main

ballast tank A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide hydrostatic stability for a vessel, to reduce or control buoyancy, as in a submarine, to correct trim or list, ...

s and most of her fuel. Her intended maximum diving depth was , but was reduced to once in service.Brown 1982, p. 232

Armament

''X1'' carried four QF 5.2 inch Mk I guns in twin unarmoured turrets, one forward and one aft of the

conning tower A conning tower is a raised platform on a ship or submarine, often armored, from which an officer in charge can conn the vessel, controlling movements of the ship by giving orders to those responsible for the ship's engine, rudder, lines, and gro ...

. They had a range of about . A circular trunk ran from each mounting to the

magazine A magazine is a periodical publication, generally published on a regular schedule (often weekly or monthly), containing a variety of content. They are generally financed by advertising, purchase price, prepaid subscriptions, or by a combinatio ...

in the pressure hull which contained 100 rounds per gun. A working chamber which was 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 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

rangefinder A rangefinder (also rangefinding telemeter, depending on the context) is a device used to measure distances to remote objects. Originally optical devices used in surveying, they soon found applications in other fields, such as photography an ...

on the

bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

that could be raised . Her six bow tubes for torpedoes 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.

Propulsion

The main engines were two 8-cylinder Admiralty

diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...

s with a total output of . Two auxiliary

MAN A man is an adult male human. Prior to adulthood, a male human is referred to as a boy (a male child or adolescent). Like most other male mammals, a man's genome usually inherits an X chromosome from the mother and a Y chromo ...

diesel engines taken from the German submarine ''U-126'' were installed for battery-charging purposes. For underwater propulsion, two GEC electric motors of each were fitted. It was hoped to achieve over using both diesels and electric motors together, but the highest power achieved (during a full power trial in March 1926) was . She had three groups of batteries, each with 110 cells weighing a total of .Brown 1982, p. 233 In theory she could make 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 A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. In its simplest form, it consists of an outer case with ...

was 2 minutes 20 seconds. Her handling underwater was considered superior to other submarines of the period.Akermann 2002, p. 220

Career

After ''X1'' was commissioned in December 1925 and accepted in April 1926 she made a voyage to

Gibraltar ) , anthem = " God Save the King" , song = " Gibraltar Anthem" , image_map = Gibraltar location in Europe.svg , map_alt = Location of Gibraltar in Europe , map_caption = United Kingdom shown in pale green , mapsize = , image_map2 = Gib ...

after which her main engine drive wheels were found to be damaged. After repairs she was sent to the

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

. Her

starboard Port and starboard are nautical terms for watercraft and aircraft, referring respectively to the left and right sides of the vessel, when aboard and facing the bow (front). Vessels with bilateral symmetry have left and right halves which are ...

camshaft driveshaft broke during a full-power run in January 1928 and a new set of gears was needed, but after refitting at

Malta Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...

her

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Ham ...

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.

Notes

References

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