Captain Joel R. Poinsett Pringle, Chief of Staff, Destroyer Flotillas, to Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters
REFER TO UNITED STATES NAVAL FORCES (F-3)
NO. OPERATING IN EUROPEAN WATERS,
U. S. S. MELVILLE, FLAGSHIP.
May 25, 1918.
From: Commanding Officer.
To: Force Commander.
Subject: Gunnery activities.
1. The following ideas have lately been suggested from different sources, and are now being considered by the Flotilla at large. The constant employment of the destroyers at sea makes it difficult to hold a conference of any great number of Commanding Officers, but these questions are being put to each vessel’s commander when she arrives in port, and in this way opinions will be obtained.
(a) Do you favor an increase in the number of depth charge throwers, either Thornycroft or “Y” gun type?
Seventeen boats have been questioned on this subject and they are strongly in favor of the idea. Opinions as to type vary. Some prefer all “Y” guns, other prefer Thornycroft throwers. Some suggest a combination of “Y” guns and throwers. After considering the idea I believe that to start with it might be well to mount one “Y” gun and two throwers on each destroyer, so that in case a destroyer desired to use a thrower when in close proximity to another vessel, she could use Thornycroft thrower instead of the “Y” gun. Some boats favored as many as four “Y” guns or four pairs of throwers, and it is believed that this could be carried out successfully on the new destroyers, where there is plenty of deck space and freeboard. It is also believed that these throwers or “Y” guns should be mounted in a battery close to each other, so that all could be loaded by the same crew, using one or two davits.
(b) Do you favor the modification of the depth charge pistol to permit a setting up to 300 feet?
This idea has met with almost universal approval, in view of the fact that it is said that the new German submarine can dive to the depth of 300 feet, and that from a statement by prisoners it has been learned that the submarines feel fairly safe when they can go underneath our depth charges. This modification might mean a strengthening of the depth charge casing to prevent crushing, and a slight modification of the pistol, which I believe could be carried out with the facilities on board the MELVILLE.
(c) Do you favor a larger depth charge, carrying up to 600 lbs. of T.N.T., to be carried in limited numbers, two or three on each boat, launched from chutes or tracks only, and to be used only when you are sure that you are in the immediate vicinity of a submarine?
This subject was brought forward by the Commander-in-Chief, Coast of Ireland, and was prompted, I believe, by the rumor that the new German submarine is built with a double hull and has armor over certain portions. This idea also met with approval of Commanding Officers of 14 out of 15 boats questioned. Referring to Bureau of Ordnance drawing, sketch No. 15197, titled “Effect of explosion of T.N.T. under water”, it will be seen that increase of charge from 300 lb. to 600 lb. will only increase the radius of destruction from 70 ft. to 95 ft., but Commanding officers seem to feel that the use of one or two of these charges when they know they are in the vicinity of a submarine would have much greater effect than the present 300 lb. charge. It is believed that these charges could be safely carried by boats of the CALDWELL class and later, and perhaps one or two could be carried by 1,000 ton destroyers. Attention is also invited to thatfact that the complete charge would probably weigh nearly 800 lb.
(d) Do you favor the installation of a depth charge howitzer which would permit you to place a depth charge weighing 262 lbs. (of T.N.T.) up to a distance of 300 yards from your ships?
The Commanding Officers favored the general idea. The installation of the depth charge howitzer which would permit them to place a depth charge near a submarine which might come to the surface inside of their turning circle. It would also enable them to largely increase the size of the pattern when attacking a submarine whose position was only approximately known. They were, however, against the mounting of such a gun unless sufficient deck space and strengthening was available. There are at present four or five 7.5” howitzers at Haulbowline belonging to the British Navy. These howitzers weigh one ton 17 cwt. and can fire a 100 lb. charge with 42 lb. of T.N.T. a distance of 2100 yards, or a stich bomb weighing 525 lbs. with 260 lbs. of T.N.T. a distance of 300 yards. As a general proposition, it is believed that boats of the Manly, Stockton, CALDWELL class and later could mount one of these howitzers to advantage. There is probably not room on the 1,000 ton destroyer to accommodate it. Since the removal of the after 3” guns on the 750 tonners, it might be possible to mount a howitzer on this vacant gun foundation for trial. Should the Force Commander approve this idea, it is believed that one of these howitzers could be obtained from the British government and a test made.
(e) Do you favor a modification of the depth gear on your torpedoes which will permit a depth setting up to 60 ft. when you wish to use your torpedoes against a submarine?
The consensus of opinion on this question has not yet been obtained, but it is believed that this should be done. It is understood that the periscope of the German submarine extends 20 ft. above the conning tower, and that the conning towers of the submarine vary in height from 5 ft. to 10 or 12 ft. With the present possible setting of 25 ft. on our torpedoes, the only part of a submarine that could be hit when running with her periscope exposed one or two feet would be the periscope itself or the conning tower. This is believed to be too small a target against which to launch torpedoes. By increasing the depth setting we could make a direct hit on the hull of the submarine itself. It is believed that this modification could be made at the Torpedo Repair Station at this base, and they are now experimenting with the depth gear.
(f) What do you consider the best location for the gun director station on board a destroyer?
Only a limited number of boats have been approached on this question, but the only answer seems to be to build a stout platform above the bridge for the mounting of the director and necessary fire control apparatus.
(g) It being probably necessary to equip torpedo tubes of the present boats with a heating device for severe winter weather, do you favor an electric heater or a steam heating device?
No opinions have yet been obtained on this subject, but in view of the fact that torpedo tubes in rough winter weather are usually submerged a great part of the time, it is believed that a stream heating device would be much more successful.
2. The U.S.S. CALDWELL has already held a director firing practice, but her reports have not yet been submitted. The following general information was obtained from her Commanding Officer in a conversation:
Practice was purposely held under most adverse conditions which could be found at this time. The roll of the ship was between 20 and 30°. There was considerable spray. The practice, considering that it was the first of its kind held with a new director installation on destroyers, was considered very successful, but it was also found that there would probably have to be certain modifications made to make the system meet all the conditions found on board a destroyer when firing in rough weather. It is to be understood that the director system on the CALDWELL was installed by the officers of the CALDWELL under the direction of her Commanding Officer, and while not exactly like the standard system proposed, it is nearly so, and in some features probably superior to the standard system.
It was found that the directorscope had to be modified, first, it was only possible to follow the roll of the ship 10°, owing to a limiting stop on the directorscope. This stop was removed, and the director can now follow the roll through 20 to 25°.
The Ford Range Keeper has been connected direct to the directorscope by means of sprocket wheels and chains, so that when the directorscope revolves in azimuth, the Ford Range Keeper also revolves, maintaining the proper relation between your ship and the enemy’s ship, and doing away with an extra operator. This is considered an excellent idea. The Commanding Officer of the CALDWELL expresses his doubt as to whether or not the follow-the-pointer system could be successfully used in director firing on a destroyer. He strongly favored modification of the trainer sight so that it could be moved in elevation and the trainer could follow the target throughout the roll of the ship. One of his sights has been so modified, and a complete test will be made of it on his next director practice, which he hopes to hold in a day or so. This does not mean that the follow-the-pointer system should be removed, or charged in any way, as of course it would be invaluable in assuring yourself that all guns were on the correct target and that the shifting of targets could be done quickly and efficiently. He also believed that a modification of the firing contact as installed on the battleship directors was necessary, and he has made such modification, which is believed should prove a success and an improvement over the present contact now installed. This will also be tried out on the CALDWELL’s next practice.
The azimuth pointer on the directorscope had to be changed, as it was so located that it was hard for the director operator to see.
In the CALDWELL system of director fire control, the gun loader path compensating cam is not connected to the roller path in any way, but is entirely separate and as the gun is trained in azimuth the gun layer sets this compensating cam to the proper bearing on which the gun is trained.
Upon the completion of the CALDWELL’S next director practice, the Force Commander will be informed of the points developed in the use of the director system.
3. A modification has been made to the hydraulic release of depth charges on the DAVIS, O’BRIEN, CALDWELL, and one or two others. Instead of mounting on chutes equipped with the hydraulic release gear, the hydraulic release gear is mounted on the after end of the depth charge tracks so that the first charge in each track can be released by this gear. This equipment has worked very satisfactorily, and it is believed to be a great improvement over the idea of carrying extra chutes, as it does away with the depth charges hanging over the side and means greater safety to the ship in case of collision. It might be well to mention here that the TERRY and DIXIE are now experimenting with the pneumatic depth charge release from the bridge, which will permit each and every depth charge on the tracks to be released from the bridge under pneumatic control.
4. It is probable that as this base expands and more boats arrive, it will be necessary to provide considerable space for ammunition and depth charge stowage. The large increase in the use of depth charges is going to make it necessary to keep at least 500 to 1000 on hand at all times. The magazines of the DIXIE and MELVILLE are now full, and it has been necessary to stow at Rocky Island 1000 rounds of 4” and 3” ammunition.
5. The instructions contained in the Force Commander’s letter No. M-4 17939 of May 17, 1918, are being carefully considered, and it is hoped that in a short time complete plans for the enlargement of the Torpedo Repair Station can be forwarded.
J R. POINSETT PRINGLE