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ASDIC Equipment Installation In Early Royal Navy Submarines

The first Royal Navy Submarine to be fitted with an ASDIC Installation was, Barrow built Submarine H32 which acted as a test bed for an ASDIC Equipment based on a system fitted in Surface ships. The H32 installation of ASDIC Type 113X (approved for fitting in 1922 and probably installed during a refit) provided guidance for the use of the ASDIC installation in Submarine X1 (completed at Chatham Dockyard in 1925). Additionally ASDIC installations were fitted in four L50 Class submarines. HMS Oberon was completed with a later version - ASDIC Type 113C.

It is probably correct to say that, prior to HMS Oberon, prototype ASDIC Type 113X was fitted in H32, X1 and the four 'L50 ' boats and the first 'Production' variant ASDIC Type 113C was installed in HMS Oberon

The following ASDIC information is adapted from:

  • The National Maritime Museum's X1 Ship's Cover dated 12th May 1923
  • Ron Cook's book 'X1 The Royal Navy's Mystery Submarine' Pen & Sword Books ISBN 978 184 832161 8
  • BR3043
  • 'Seek and Strike' by Willem Hackman - HMSO 1984, ISBN 0-11-290423-8

ASDIC Type 113X Installation in Submarine X1

In a memorandum dated 30th December 1921, designer A W Johns addressed himself to the questions of sending and receiving messages - both surfaced and submerged - and raised the possibility of installing the new ASDIC apparatus into Submarine X1. Submarines had, up to this time, relied on hydrophone installations for detection of ships and other submarines, following trials and investigations conducted by Commander Ryan and his team at HMS Tarlair. However these hydrophone installations were unable to provide accurate bearings and could not provide ranges.

Commander Ryan's trials had culminated in the installation of an array of five hydrophones in the R Class Submarines. These submarines, ordered in the later stages of the First World War, were designed as anti-submarine submarines with a large bow salvo of six 21 inch torpedoes, increased battery power and streamlining to give high underwater speed. Of the twelve R Class submarines ordered two were cancelled in Aug 1919, eight were scrapped in Feb 1923 and only two survived with R10 in service until 1929 and R4 until 1934. However these two submarines only appear to have been used in the 'Clockwork Mouse' role and not in the development of 'Anti-Submarine' or 'Anti Surface Ship' tactics. Submarine to Submarine Communications had been installed in some Royal Navy submarines from pre-WWI days using the American designed Fessenden transmit/receive equipment.

ASDIC had been invented in the latter stages of the Great War as a replacement for the extempore hydrophone installations in surface warships, which were then the only means of detecting a submerged submarine. ASDIC became widely fitted to surface ships of the Royal Navy, and it was erroneously believed by many to have rendered the submarine impotent.

In his memorandum, A W Johns proposed that the question of whether or not to fit ASDIC in Submarine X1 (then building in HM Dockyard at Chatham) should wait on future trials with Submarine H32. H32 had been built by Vickers at Barrow-on-Furness and had been commissioned on 27th May 1919. In 1921 design work had begun on a submarine ASDIC, based on the prototype equipment first fitted to a 'P' Boat (surface warship), but inverted. Designated ASDIC Type 113, it first went to sea in Submarine H32 in 1922. The quartz transducer was fitted inside a retracting canvas-covered dome, which required a period of immersion before it became sound-transparent. The troublesome canvas dome was soon replaced by a copper one.

Initial results from trials in H32 were obviously promising for, on 12th May 1923, approval was given to fit an ASDIC installation in Submarine X1. She would be the first submarine to be designed as such to have an ASDIC compartment installed. As at 26th January 1925 Submarines H32 and X1 were the only submarines so far fitted with ASDIC but four in No. 'L50 ' Class submarines were to be fitted with ASDIC while building.

The ASDIC equipment fitted in X1 was designated the Type 113X, and was strengthened for deep diving. It was also provided with a hinged cover to protect the oscillator dome from gun blast. In 1930 X1's ASDIC had its electronics updated and it was re-designated the Type 113C.


The ASDIC Type 113X Turret ready to be installed in Submarine X1. This is a mock-up showing the Control Wheels and the hinged Turret Cover. The framework covering the Oscillator was to be fitted with a canvas cover as on H32 but, in practice, it was replaced with a thin copper dome. This item was extremely fragile and when removed for maintenance required careful handling.


Drawing showing the 2-Ply quartz Oscillator of ASDIC Type 113X


The ASDIC Turret raised on hydraulic rams into the operating position. Oscillator vertical, facing forward


The ASDIC Turret retracted for surface action, with its hinged cover in place. Oscillator horizontal, with the original design of frame for a canvas cover.


The ASDIC arrangements showing the Silent Compartment, with its double wheel (Item 37) for training and elevating the Oscillator, the pair of headphones (Items 17) for the Operator and an Officer, the Morse Key (Item 21), the operating rods for the ASDIC Turret (Item 53), and the repeater rod to the Control Room (Item 46). Also shown in side view is the hinged cover which protects the ASDIC Turret from the blast of 'A' Turret's Twin 5.2 inch guns close overhead.


Section looking aft through the sound-insulated Silent Compartment on the left, where the operator sat, and the ASDIC Office to the right, containing the electrical equipment.


David Hill's drawing of 'A' Turret Trunking with, on the right, the door to the ASDIC Silent Compartment

Since Submarine X1 was of a size to present a tempting target to smaller, submerged boats, her ASDIC set was designed to detect other submarines as well as surface targets.

The equipment also had an important navigational function in X1, as befitted her role as a 'Corsair' submarine in the wide blue yonder. Vast areas of the sea had been surveyed by surface ships, but depths and rocks had only been investigated down to about 70 feet. X1's ASDIC enabled her to detect and avoid uncharted rocks when she was proceeding submerged.

The original intentions were that ASDIC was to be used for navigational purposes and target ranging, and also for communications. It offered the possibility of coordinating divisional attacks by several boats at once.

ASDIC brought many advantages.

Trials were carried out with H32 between June 1925 and January 1926, and the reports were copied to Lt-Commander Phillips - the Commanding Officer of Submarine X1 as to:

  • station-keeping with another non-ASDIC equipped submarine
  • attacking without periscope exposed after an initial periscope sighting had been made
  • avoiding anti-submarine attacks by surface escorts
  • transmitting of messages between surface vessels and submerged submarines
  • firing torpedo spreads on ASDIC bearings

Excellent results were achieved, and the ASDIC set in H32 was used to complement the underwater directional hydrophone receiver. It was found that submarine ASDIC was less affected by surface disturbances. High speed, which disrupted surface ASDIC, was not a problem for a submerged submarine owing to the very low speed of dived submarines achieved prior to the later stages of the Second World War.

ASDIC pulses could be transmitted and received on a range of frequencies. This ability could be used to differentiate between attacking anti-submarine vessels, and also to actively range on anti-submarine vessels not transmitting - if their search frequency was known - the submarine transmitting pulses on a different band to avoid the chance of the surface sets homing onto the submarine.

The major problem with keeping an extended ASDIC watch was the monotony of the operation, which resulted in extreme operator fatigue, and necessitated frequent relief operators. Obviously, a large submarine such as X1 could carry a sufficient number of operators to mitigate this factor. Unfortunately, despite the pioneering work done by Submarines H32 and X1, Royal Navy submariners would not use their ASDIC for torpedo attacks - avoiding emitting active signals (which would alert an enemy) and using their ASDIC equipment as a passive hydrophone receiver only. The results achieved in all the above trials foreshadowed the much later work of the USN and RN nuclear hunter-killer submarines.

Further to the experimental & prototype ASDIC Installations in Submarines H32 and X1 ASDIC equipment was also installed in four 'L50 ' Class Submarines. These Submarines were L54, L56, L69 & L71.

Submarine H32 was built by the Vickers Shipyard at Barrow in Furness. The Submarine was 'Laid Down' on 20th Apr 1917, 'Launched' on 19th Nov 1918 and 'Completed' on 27th May 1918. The ASDIC equipment was installed in 1922.

Submarine L54 was built by the William Denny Shipyard at Dumbarton. The Submarine was 'Laid Down' on 14th May 1917, 'Launched' on 20th Aug 1919 and 'Completed' in HM Dockyard, Devonport on 27th Aug 1924. The ASDIC equipment was probably fitted during the build.

Submarine L56 was built by the Fairfield Shipyard at Govan on the Clyde. The Submarine was 'Laid Down' on 16th Oct 1917, 'Launched' on 29th May 1919 and 'Completed' on 3rd Sep 1919. The ASDIC equipment was probably fitted during a refit.

Submarine L69 was built by the J Samuel White Shipyard at Cowes on the Isle of Wight. The Submarine was 'Laid Down' on 7th Jul 1917, 'Launched' on 6th Dec 1918 and 'Completed' in HM Dockyard, Rosyth on 18th Apr 1923. The ASDIC equipment was probably fitted during the build.

Submarine L71 was built by the Scotts Shipyard at Greenock on the Clyde. The Submarine was 'Laid Down' on 29th Sep 1917, 'Launched' on 7th May 1919 and 'Completed' on 23rd Jan 1920. The ASDIC equipment was probably fitted during a refit.

Submarine X1 was built in HM Dockyard at Chatham. The Submarine was 'Laid Down' on 2nd Nov 1921, 'Launched' on 16th Jun 1923 and 'Completed' on 23rd Sep 1925. The ASDIC equipment was fitted during the build.

ASDIC Type 113C (the production version) became a standard installation in Submarines built from the Royal Navy from HMS Oberon onwards.

Submarine HMS Oberon was built in HM Dockyard at Chatham. The Submarine was 'Laid Down' on 22nd Mar 1924, 'Launched' on 26th Sep 26 and 'Completed' on 24th Aug 1927.

The seats for the ASDIC Installations were completed in the Submarine Building Yard but the ASDIC Equipment was fitted in Naval Dockyards.


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