HM Submarine X1

HM Submarine X1 was conceived and designed as a submersible commerce raider for the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

; at the time of her launching she was the largest submarine in the world. The idea of a submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

A cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...

 had been proposed as early as 1915, but was not put into practice until 1921. X1, which was based on the uncompleted German U-173 class of 2,000-ton "U-Cruisers", was laid down on 2 November 1921 at the Naval Dockyard Chatham
Chatham Dockyard
Chatham Dockyard, located on the River Medway and of which two-thirds is in Gillingham and one third in Chatham, Kent, England, came into existence at the time when, following the Reformation, relations with the Catholic countries of Europe had worsened, leading to a requirement for additional...

 and completed on 23 September 1925, commissioning in December 1925.

The 1922 Washington Naval Treaty
Washington Naval Treaty
The Washington Naval Treaty, also known as the Five-Power Treaty, was an attempt to cap and limit, and "prevent 'further' costly escalation" of the naval arms race that had begun after World War I between various International powers, each of which had significant naval fleets. The treaty was...

, of which Britain was a signatory, did not ban submarines but it did ban their use against merchant ships, which was X1s unacknowledged purpose; its armament had been designed to successfully engage the classes of vessels likely to be escorting convoys, such as destroyers and frigates. 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.


The X1s 1 inches (2.5 cm) thick pressure hull was 19 foot in diameter amidships, and was divided into 10 water-tight compartments. This was almost completely surrounded by her external hull which also contained the main ballast tank
Ballast tank
A ballast tank is a compartment within a boat, ship or other floating structure that holds water.-History:The basic concept behind the ballast tank can be seen in many forms of aquatic life, such as the blowfish or argonaut octopus, and the concept has been invented and reinvented many times by...

s and most of her fuel. Her intended maximum diving depth was 500 feet (152.4 m) but was reduced to 350 feet (106.7 m) once in service.

She was expected to sink her targets using gunfire and so was given four 5.2 inches (13.2 cm) guns to be able to defeat a destroyer or armed merchant ship although she was fitted with six bow tubes for 21 inches (53.3 cm) torpedoes
British 21 inch torpedo
There have been several British 21-inch diameter torpedoes used by the Royal Navy since their first development just before the First World War.They were the largest size of torpedo in common use in the RN...

 to supplement her guns.


X1 carried four QF 5.2 inch Mk I guns in twin unarmoured turrets, one forward and one aft of the conning tower
Conning tower
A conning tower is a raised platform on a ship or submarine, often armored, from which an officer can con the vessel; i.e., give directions to the helmsman. It is usually located as high on the ship as practical, to give the conning team good visibility....

. They had a range of about 16000 yards (14,630.4 m). A circular trunk ran from each mounting to the magazine in the pressure hull which contained 100 rounds
Cartridge (firearms)
A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically...

 per gun. A working chamber which was 10 feet (3 m) 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 no less than 58 crewmen. The fire-control tower was in the middle of the sail
Sail (submarine)
In naval parlance, the sail or fin of a submarine is the tower-like structure found on the dorsal surface of submarines...

 and had a top that could be raised 2 foot (0.6096 m) 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 9 feet (2.7 m) rangefinder
A rangefinder is a device that measures distance from the observer to a target, for the purposes of surveying, determining focus in photography, or accurately aiming a weapon. Some devices use active methods to measure ; others measure distance using trigonometry...

 on the bridge that could be raised 8 feet (2.4 m).

Her six torpedo tubes came from a cancelled L-class submarine
British L class submarine
The British L class submarine were originally planned under the emergency war programme as an improved version of the British E class submarine. The scale of change allowed the L class to become a separate class....

 and she was provided with one reload for each tube. It took some 24 minutes to reload them all because her torpedo room was space restricted.


The main engines were two 8-cylinder Admiralty diesel engine
Diesel engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, which is injected into the combustion chamber...

s with a total output of 3000 hp. Two auxiliary 1200 hp MAN Diesel engines taken from U-126
SM U-126
SM U-126 was one of the 329 submarines serving in the Imperial German Navy in World War I.U-126 was engaged in the naval warfare and took part in the First Battle of the Atlantic....

 were installed for battery charging purposes. For underwater propulsion, two GEC electric motors of 1000 hp each were fitted. It was hoped to achieve over 8000 hp using both Diesels and electric motors together, but the highest power achieved (during a full power trial in March 1926) was 7135 hp. She had three groups of batteries, each with 110 cells weighing a total of 70 long tons (71.1 t).

In theory she could make 19.5 knots (38.2 km/h) 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 X1s average diving time (to periscope depth) was 2 minutes 20 seconds. Her handling underwater was considered superior to other submarines of the period.


After X1 was commissioned in December 1925 and accepted in April 1926 she made a voyage to Gibraltar
Gibraltar is a British overseas territory located on the southern end of the Iberian Peninsula at the entrance of the Mediterranean. A peninsula with an area of , it has a northern border with Andalusia, Spain. The Rock of Gibraltar is the major landmark of the region...

 after which her main engine drive wheels were found to be damaged. After repairs she was sent to the Mediterranean Sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

. Her starboard
Port and starboard
Port and starboard are nautical terms which refer to the left and right sides, respectively, of a ship or aircraft as perceived by a person on board facing the bow . At night, the port side of a vessel is indicated with a red navigation light and the starboard side with a green one.The starboard...

 shaft broke during a full-power run in January 1928 and a new set of gears was needed, but after refitting at Malta
Malta , officially known as the Republic of Malta , is a Southern European country consisting of an archipelago situated in the centre of the Mediterranean, south of Sicily, east of Tunisia and north of Libya, with Gibraltar to the west and Alexandria to the east.Malta covers just over in...

 her port
Port and starboard
Port and starboard are nautical terms which refer to the left and right sides, respectively, of a ship or aircraft as perceived by a person on board facing the bow . At night, the port side of a vessel is indicated with a red navigation light and the starboard side with a green one.The starboard...

 shaft 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
Pembroke Dock
Pembroke Dock is a town in Pembrokeshire, south-west Wales, lying north of Pembroke on the River Cleddau. Originally a small fishing village known as Paterchurch, the town was greatly expanded from 1814 onwards following the construction of a Royal Naval Dockyard...

 on 12 December 1936.

See also

  • British M class submarine
    British M class submarine
    The British Royal Navy M-class submarines were a small class of diesel electric submarine built during World War I. The unique feature of the class was a 12-inch gun mounted in a turret forward of the conning tower.-Background:...

     — an earlier attempt at a gun equipped submarine
  • Surcouf — a similar French large gun-armed submarine

External links

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