Memorandum to Committee on Standard Plans, Fleet Emergency Corporation
August 8, 1917.
Memorandum for the Committee on Standard Plans, Fleet Emergency Corporation.1
SUBJECT:- Submarine Defense Schemes.
1. LOW VISIBILITY OF SUPERSTRUCTURE.
The board is of the opinion that too much stress should not be laid on the theoretical figures submitted by the Ship Production Committee in their paper of July 13th.2 There are so many other questions besides those of low visibility which enter into the makeup of a seagoing craft that it is not practicable to reduce the heights of the superstructure below a certain figure. The necessity to cruise deep laden, to be habitable in rough weather as well as smooth, to carry guns and boats, and make provisions for living quarters that will be habitable, all render a certain height of hull above water a thing which cannot be avoided. In this connection it is well to state that it is common belief that the flush-deck type of ship silhouetted against the sky line at any distance is not so noticeable as the well-deck type of ship which looks like three islands and makes a decided break in the horizon line at any distance.3
This is a feature in ship production which will bear considerable investigation. There are several systems under investigation. It is current report that the periscopes are fitted with glasses which will silhouette a ship painted a uniform color in sharp outlines against the sky. In any scheme of painting it should be realized that the sky will be the background and that the colors to be used will depend to some extent upon the character of the background and the atomospheric conditions. Any scheme of painting must break up the straight lines and should endeavor to deceive the submarine observer both as to the character and class of the ship and the direction in which she is going. The two sides of a ship should be painted differently.
3. ARRANGEMENTS AND NUMBERS OF MASTS, DERRICKS, ETC., ABOVE UPPER DECK.
All reports indicate that only one mast should be used and that this mast should be very close to the funnel. Reports further indicate that not more than one funnel should be used. In the case of vessels fitted to burn oil fuel, especially where the engines and boilers are place aft, there is a question whether the lowermast itself might not be used as a funnel. This would give the added draft and tend to decrease the size of the funnel. The smoke problem is cared for by the use of oil fuel. It would seem wise to make the topmast the housing torpmast. With regard to the number of derricks, it is an important feature to make them housing as far as is practicable, but an even more important feature is to stagger them or arrange them in such manner that the submarine cannot get an indication of the course by getting the derricks in line. The two elements necessary for the submarine to make a fairly accurate calculation in order to make a hit are the speed and course of the target. Any objects on the ship which stand out and give a submarine an indication of the course are dangerous for, owing to the proximity of the submarine to the ship at the time she discharges the torpedo, a very close estimate of the course can be made if there are any objects to line up on.
4. SUBMARINE DETECTION DEVICES.
While not as yet perfected any listening devices similar to those furnished by the Submarine Bell Signal Company will be found useful in warning a ship of the presence of a submarine if the submarine is under way.4 An important feature in handling this apparatus efficiently is to have the personnel trained to use it. It requires a trained personnel in much the same manner that radio requires trained personnel.
5. LOOKOUT STATIONS.
Every ship must be provided with a sufficient number of lookout stations to insure that every portion of the horizon is under observation at all times. These lookout stations should be at several levels and should be well protected against the weather.
6. ARMING AND NUMBER OF GUNS.
It is believed that every ship traveling the submarine zone should be armed and that the number of guns should be about four. For the large ships the 5” 50 caliber is a good gun. The 4” is a most excellent size for medium sizes. No guns less than three inches should be used, except machine guns for close work. One or two of these machine guns or one-pounders for close-in work would be useful.
7. SMOKE DEVICES.
The British have a smoke box device which has been found somewhat useful. With our destroyers a very effective method of laying a smoke screen is found in forcing the boilers. It seems probable that in the oil-burning merchant ships arrangements could be made by firing the furnaces in certain ways to produce a cloud of smoke out of the funnel and thus make a very effective screen.
Every ship should be fitted with radio. It is believed that it is not necessary to carry the two masts in order to get as efficient radio service as it will be necessary for these ships to carry. In carrying the sets from the masts toward the deck it would seem wise not to attempt a symmetrical arrangement, for such an arrangement would be almost sure to give the submarine a line on the fore and aft direction of the ship.
9. SUBSTITUTION OF SHIPPING – BEST AND FASTEST CRAFT FOR THE WAR ZONE.
As a matter of policy, wherever it is practicable to do so, the slowest ships should be put on the safest routes, namely, in the Pacific, into the South American trade, into the Asiatic trade and the West Coast. By so doing, certain better and faster craft might be released for trans-Atlantic service.
Source Note: DT, DNA, RG 45, Entry 520, Box 341.
Footnote 1: The Fleet Emergency Corporation was created to organize the construction of the American merchant and naval fleet.
Footnote 2: The document referred to has not been found.
Footnote 3: Well decks have a broken deck line, while flush decks have a consistent deck line from bow to stern.
Footnote 4: For more on the device, see: William S. Benson to William S. Sims, 11 August 1917.