Skip to main content

Captain Richard H. Leigh, Assistant Chief of the Bureau of Steam Engineering, to Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters


December 7, 1917.

From:     Captain R.H. Leigh, U.S. Navy.

To:       The Commander, U.S. Naval Forces,

           in European Waters.

          I have been directed by the Navy Department to report to you with certain officers, men, civilian employees and apparatus consisting of the latest underwater sound detection devices developed in the United States under the supervision of the Navy Department.

          The purpose of the Navy Department in sending this party and material to English waters is to have the devices demonstrated before the proper authority of the British Admiralty by those most intimately connected with its development and by a Naval personnel which has been trained in its use.

          It is considered desirable that demonstrations should first be made by operating against a British submarine until the crews of the chasing vessels are drilled in the manoeuvering signaling and the methods of operation and then to make every effort to get in contact with an enemy submarine with a view to its detection pursuit and destruction.

          The equipment brought from the United States is sufficient to complete the outfit of three vessels including in addition to the sound detection devices, certain special signaling apparatus and radio telephones.

          It is desired to have this equipment installed on three vessels similar to the 110 ft. submarine chasers of the United States larger than these chasers. It is not believed that a proper demonstration can be made on smaller vessels and it is earnestly requested that in order to give the apparatus a fair trial large vessels be assigned to this duty. It is absolutely essential that the vessel on which the apparatus be installed have the following characteristics: High speed, ability to start and stop quickly, quick manouevering powers, and cessation of all noises when stopped. Batteries should be sufficient for defence against submarine gunfire and they should each carry at least six depth charges of 300 lbs. weight per charge.

          In operations against enemy submarines it is desired to bring strongly to your attention the absolute importance in keeping the area of search and pursuit entirely clear of shipping. Without doing this it is doubtful if any operations can be successfully carried out, noises from other vessels interfere materially with hearing the enemy submarines and if shipping is permitted in the vicinity of the search and pursuit a case may readily arise where the noises from such vessels would entirely drown out those of the enemy submarines thus permitting escape.

          To utilize the full capabilities of the apparatus it is desirable to keep vessels twenty-five miles away from the vicinity of the search and pursuit, though reasonable results may be expected if shipping is kept fifteen miles away.

          It is estimated that it will take four days to properly install the equipment on the vessels designated for this duty. This includes the work of installing the S.C.C.-Tubes that is the tubes through the bottom of the vessels, for which work the vessels would have to be docked.

          It is estimated that then days to two weeks will be required to properly demonstrate the apparatus and drill the vessels after its installation. The vessels should then be ready to undertake operations against enemy submarines.

          In addition to the apparatus to be installed on the searching vessels there has been brought to the United States one S.C-Tube for installation through the upper deck of a British submarine. It is estimated that this installation will require ten days. It is not necessary to dock the submarine in order to do this work.

          There accompanies this letter a full description of all apparatus brought from the United States together with instructions as to its installation and reports of their performance characteristics.

          It is suggested that a conference be held with the officers and technical experts under my charge and as many officers as may be practicable from our destroyers which have been operating in European waters in order to fully discuss the question of the problem of hunting the enemy submarine and the possibilities of these detection devices.

              /s/ R.H. LEIGH.



     In undertaking the detection, pursuit and attack of an enemy submarine with the apparatus brought from the United States, it is proposed to use three vessels similar to 110 ft. U.S. Chasers but of larger size. The essential requirements are adequate armament, quick attainment of high speed, 16 to 20 knots, ease in handling when under way, quick stopping and elimination of all noise when stopped. A vessel of wooden construction is preferable to one of steel or iron; this applies particularly to the vessels on which the S.C.C-Tubes are to be installed. If the S.C. C-Tubes are installed on steel or iron vessels sound insulation should be used between the tubes and vessel hull.


     It is proposed to use the K-Tube, C-Tube, Multiple Receiver and Indicating Trawling Wire apparatus all of which are fully described in separate correspondence.

     The K-Tube (long range), The C-Tube (short range), and Multiple Receiver devices give the direction of an enemy submarine which is under way but can only be used from a vessel which is drifting, or at anchor in a tideway of not more than one knot.


     The necessity of stopping to use this apparatus governs this system of attack. If ships are patrolling and wish to use this device they must proceed by a series of starts and stops, all moving together, or the must form a drifting patrol.

     After the submarine has once been heard contact must be maintained and the chance must be so manouevered as to assure a successful bombing attack. It is essential that the formation of the Chasers be such that good sound bearing cross cuts can be secured thus fixing the position of the submarine within very small limits, as nearly a right angle cut as possible being most desirable.


     It can not be too strongly urged that all officers and men directly engaged in the work understand the whole operation and are thoroughly drilled before attempting an attack upon an enemy submarine; only by good team work can success be achieved. Each ship must be organized in detail for this special service so as to carry out the operations of listening, signaling, manouevering, etc., with the utmost rapidity. Every special duty must have its appointed man and this man must be thoroughly drilled in the work he is to do.


     The manouevering, the flagboat controls. The manouevers, in general, consist of three parts: The Hunt; The Pursuit; The Attack.

The Hunt:- Three conditions may arise during the hunt –

     a.   The submarine, or its periscope, may be seen by one of

          the chasers.

     b.   The Chasers may be listening on K-Tubes, while

          drifting about five miles apart in line.

     c.   The Chasers may be advancing intermittently, starting

          and stopping together, listening on C-Tubes during

          stops. In this case the formation would be line,

          interval about one mile.

The Pursuit:- Whenever one of the chases sees or hears the

submarine it immediately signals the bearing and estimate of distance and all will then take up the pursuit and manoeuver in accordance with the signals from the Flagboat. The Flagboat will so manoeuver the Chasers as to close in on the submarine as quickly as possible, making every effort to close all Chasers to within 500 yards of the submarine preparatory to attack.

The Attack:-  When the submarine has been brought within

attacking distance, the chasers being in line, 500 yards interval, the Flagboat then designates any one, or more, of the Chasers as attacking boat and will direct the attack. The attacking boat, or boats, proceed to point, or points designated and drop bombs as directed.

     If for any reason it is desired to call off the attack and manoeuver again for a favourable position, the Flagboat will give the necessary signal. If at any time a Chaser finds itself in such condition as to be unable to execute instructions, such Chaser will immediately notify the Flagboat.


1.   The Commanding Office, in charge.

2.   An Assistant.

3.   Four Listeners (two trained U.S.).

4.   Two angle indicator officers.

5.   Two plotters.

6.   Two manoeuvering signal operators.

7.   The signal observers.

8.   Two Radio Telephone men.

9.   Three Lookouts.

10.  One Recorder.

11.  Two Tube Tenders.


     The Commanding Officer: in command, is at all times responsible for the safety of the ship and the proper conduct of the hunt, pursuit and attack. On the Flagboat he will

     a.   Instruct the plotter.

     b.   Decide the courses to be steered.

     c.          “ distance to be run on any one course.

     d.          “ speed.

     e.          “ distance between chasers.

     f.   Give orders for starting and stopping.

     g.   Supervise signals.

     h.   Instruct recorder.

     i.   Give orders for the attack.

     j.   Maintain silence when vessel is stopped.

     On other than the Flagboat the Commanding Officer will be responsible for a, f (for his own vessel), g, h and j, above and for immediate compliance with signals from Flagboat.

     For his assistance in manoeuvering each Commanding Officer should prepare a table, or diagram, showing the time, in minutes and seconds at half, or full speed, for the following distances: 1/8, 1/4, 1/2, 3/4, 1, 1 1/2 and 2 nautical miles.

     If ship, after a stop, has to make a wide turn to get on a new course, the Commanding Officer to start timing for distance run when she is on the required course, and to simultaneously advise recorder. Due allowances to be made in the new course for the turn, using tables and curves previously prepared.

     Deviation of compasses is to be carefully checked. All vessels to have deviation tables and in signals for courses or directions are always to be magnetic.

     In stopping the ships do so in the shortest time possible, killing all headway and so use rudder and engine that the ship will swing as little as possible after stopping.

     The Assistant – will assist the Commanding Officer as directed. It is suggested that he give special attention to signals, the plotting board and recording.

     The Listeners – See that tube is lowered immediately the vessel is stopped and begin listening at once. On hearing a ship noise consult with the Commanding Officer before announcing to the bridge. The Commanding Officer will notify the listeners of the presence of surface craft, or unusual account of bubbles.

     Immediately on definitely identifying the sound as that from a submarine, he will sing out “stand by”. He then listens for direction and upon getting this sings out “Mark”. (At this time helmsman notes ships heading to be used in calculating the magnetic bearing.) The Listener then reads the angle of direction of the sound and immediately reports it, together with an estimate of the audibility, as “Direction 97, Very Faint”.

     Listener must remember to turn C-Tube pointer outboard before it is hauled up to prevent tube fouling hull.

The Angle Indicator Operators: Set the arm at the bearing angle as directed. This angle is not the angle called out by the listener but must be the magnetic bearing angle received from the Commanding Officer. The device is to be turned first to face the Flagboat and left that way for about half a minute, then turned to face the other operating vessel. Then turn back to Flagboat.

The Plotters: Keep track of Chasers and reported position of submarine, noting and recording time of each maneuver. Immediately on each stop make sketch plot on cross section paper of the three chasers, from bearings and distances obtained from ships observers, and when bearing of the submarine is obtained on own ship, or signaled from others, sketch in these bearings. Use separate azimuth paper sheet for each sketch, entering time of stop on lower right hand corner. Plot on main track sheet position of chasers and submarine thus ascertained, noting at each position the time of observation.

The Signal Observers: Keep very careful, look-out and report immediately to Commanding Officer all signals seen and answers to signals made. Be sure of signals before reporting.

The Signal Operators: Make quickly all signals required by the Commanding Officer. Study carefully instructions in regard to signals and be sure to make no mistake.

The Radio Telephone Men: Keep radio telephones in good operation condition standing by them during operations.

The Lookouts: must be well trained, one to keep intensive watch in section where submarine is reported. The Lookouts are to be supplied with best binoculars.

 Note:-  In addition to the special details required for the work of searching for the enemy submarine as outlined above, the regular helmsman has a very important part to play and is of material assistance. After stopping he should call out at frequent intervals the ships heading. He must keep the inner circle of the angle calculator against the ships head on the outer dial thus as the ship swings he alters the inner circle to correspond to ships head until the Listener calls “Mark”. He then holds fast.

     When the Listener reports his angle as “Direction 100” the helmsman repeats “Direction 100” and then looks at this reading on the outer dial which is the magnetic direction, this “Bearing 223”. The Angle Operators repeat back the angle given.

The Recorder: Keeps the log in tabular form recording the following information:-

     a. Time of starting bells; minute and seconds.

     b. Course in degrees, 360 degrees basis.

     c. Time ship gets on course,      (from Commanding Officer).

     d. Distance run on course,   (                    ).

     Time stopping bells, minute and seconds.

     f. Bearing and distance of each chaser.

     g. Listeners direction angle.

     h. Magnetic         

     i. Listeners estimate of distances.

     j. General remarks.

Note: Before beginning operations Recorder must carefully check

      his time with standard of Commanding Officer.

The Tube Tenders Will

a. Stand by tubes at all times when operating.

     b. Lower tube without waiting for orders immediately ship

        is without headway.

     c. Raise tubes without waiting for orders immediately ships

        starting engine bell is sounded.

     d. See that in raising and lowering tube is kept clear

        ship’s side.

     e. Examine tube everytime it is hauled up to see everything






One C-Tube (U.S.)

One Multiple Receiver (U.S.)

One S.C. C-Tubes (U.S.)

One K-tube (U.S.)

One Radio Telephone (U.S.)

One direction indicator (U.S.)

Two Listeners Tents (U.S.)

One Position and Direction indicator (U.S.)

One Angle Calculator (U.S.)

Two supporting davits.

Two Listeners supports.

One signal chest with flags.

One range finder (small portable).

One 18” X 24” drawing board, tacks, paper, etc.

One package (24) sheets cross section paper.

One record board, with metal clips.

One set (12) sheets, log of operations.

Four small flag buoys.

Six depth bombs.

Four smoke bombs.

One bow, or stern identification ball or flag.

One set signal shapes.

     Note:- Those items marked (U.S.) to be supplied by Special

            Service Party from United States, the remainder to

            be supplied by the British Government.


Two C-Tubes (U.S.)

Two S.C. C-Tubes (U.S.)

One K-Tube (U.S.)

One 3-wire indicating trawl (U.S.) and remainder same as for Chaser A.


The same as for Chase B except –

One 1-wire indicating trawl instead of 3-wire.

Two listeners tents to be furnished by British Government instead of U.S.

Source Note: Cy, DNA, RG 45, Entry 520, Box 337. Leigh and his team of naval personnel and civilian scientists received Sims’ full support in conducting their tests in English waters during a two-week period in December 1917 and January 1918. Although none of the tests were successful, these results were hardly considered conclusive, largely due to the fact that this the experimental equipment required that the listening vessel halt its machinery and drift in silence in order to detect a submarine, something that was impracticable; it provided a submarine with considerable time to disappear before the chasing vessel could start up again and attack. Nevertheless, the U.S. Navy was quite enthused by the results, and Sims, backed by two of the civilian scientists on the mission, strongly recommended the use of the American detection equipment in favor of the British. As a result, American destroyers that had British devices on them were reequipped with American listening gear, and, starting in August 1918, all new destroyers deployed to European waters received American equipment prior to their deployment. Nevertheless, despite the copious amount of American sound detection equipment used on Allied vessels, they had little overall success in the anti-submarine warfare campaign. According to one authority, vessels equipped with the American sounding equipment were responsible for the detection and sinking of only six enemy submarines; Still, Crisis at Sea, 327-330. For Leigh's follow-up report on the results of these tests, see, Leigh to Sims, 9 January 1918, DNA, RG 45, Entry 520, Box 337