Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Rear Admiral David W. Taylor, Chief of Bureau of Construction and Repair
March 6th. 1918.
My dear Admiral,
Your letter of January 25th. asking about recognition signals for submarines, has been referred to the submarine people at Queenstown, and it comes back with the information quoted below.
I am sending you this in a personal letter because we were requested not to make it the subject of an official communication so as to decrease the chances of it getting out.
The following quotation is a description taken from a letter from one of the competent British submarine commanders and the commander of our submarine force over here:-
“1. British submarines are identified by means of signal flags, blinker tubes, smoke grenades, rockets, and painted shapes on deck. The blinker tubes are of two kinds – the Cruiser Arc Lamp and the ordinary blinker. The Cruiser Arc Lamp is a very powerful light contained in a rectangular box about 12” x 14” x 12” with a reflector; it is used in place of a signal searchlight, but on account of its size and weight, the British submarines seldom use it. The ordinary blinker is a small box about 5” x 6” x6” containing an electric light and a movable reflector such as is used on a heliograph. The box is fitted with a handle like a pistol grip which has, for the trigger, the lever for rotating the reflector. Along the top of the box is a small telescope so that blinker can be held in one hand and, at the same time, accurately pointed and operated at the ship receiving. Due to difficulty in obtaining these blinkers, as a substitute, an electric light and storage battery are combined in a small box with a make and break switch. The latter is being supplied by the British Admiralty to the submarines of the Fifth Division.
2. The grenade, used only in day-time, is a smoke bomb or rocket ejected from a Lee-Enfield rifle by the discharge of a blank cartridge. The grenade is cyllindrical, 2-1/2” in diameter and 7” long. It has a stem, 15” long which fits into the muzzle of the rifle. The bomb is ignited by a primer at the upper end of the bomb. The primer is set off by the inertia of a small hammer upon discharge of the bomb from the rifle. A safety pin is fitted under the hammer, which pin when removed arms the bomb. When the rifle is fired the grenade is thrown about 500 feet into the air and when it starts down, it throws out colored smoke which is either blue, yellow, red, or purple, depending upon the signal for the day.
3. The corresponding signal at night is a special cartridge fired from a Very’s pistol which, upon discharge, throws out a flare or call and, upon bursting, shows two light balls wither – red and green, two reds, two greens, two whites.
4. For recognition by aircraft a piece of heavy canvas about 4’ x 4’ is secured by battens to the deck near the engine-room hatch and a shape is painted in black and white on this canvas.
5. It is understood that experiments are being conducted with smoke and fire bombs to be released when submerged to stop a depth charge attack by a friendly craft.
6. The submarines of the Fifth Division have been supplied by the British Admiralty with full outfits of signal flags, smoke grenades and Very’s colored stars.
7. If it is desired, a sample bomb and a Very’s colored cartridge could be sent to the Bureau of Construction and Repair.”
In reference to the last paragraph, of course the writer has no authority to state that a sample bomb and a Very’s colored cartridge would be forwarded to the Bureau of Construction and Repair, but I am taking this up at once with the Admiralty, and I have no doubt that they will let me have the material to forward to you.
I am sorry that this matter could not have been handled more promptly.
Very sincerely yours,
S/ W S SIMS