Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to Destroyer Commanders in European Waters
UNITED STATES NAVAL FORCES
OPERATING IN EUROPEAN WATERS
U.S.S. MELVILLE, FLAGSHIP.
26 NOVEMBER 1917.
From: Force Commander.
To: U.S. Destroyer Flotillas Operating in European Waters.
Subject: Confidential Orders for Ships in Convoy.
1. There are quoted below for the information of the Force, certain comments re Cruiser Force Commander’s “Orders for Ships in Convoy”, which orders were published to the Force in the Force Commander’s mimeo. No. C-94(30)-11 of 15 November, 1917.
2. In order that suggestions for modifying and improving the instructions contained in “Orders for Ships in Convoy” may be forwarded to the Commander Cruiser Forceby the Force Commander, it is directed that, as soon as the ships composing a Troop Transport Escort have returned to their base, the Senior Officer of the Escort shall call a conference of their Commanding Officers, discuss the operations freely, and submit immediately any suggestions or recommendations that are considered as warranted. In case there are no suggestions or recommendations to be made, the Force Commander will be so informed.
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C2885 19 November, 1917.
From: Commander, U.S.Naval Forces Operating in European Waters.
To: Commander, Cruiser Force and Transport Force.
Subject: Confidential Orders for Ships in convoy.
Reference:(a) Cruiser Force and Transport Force Pamphlet of 10 October, 1917, re Orders for Ships in Convoy.
The following suggestions are offered for consideration in connection with reference (a).
FORMATION OF CONVOY.
It is recommended that there be inserted a general clause in substance as follows:-
“In general in passing through submarine waters the depth of formation should be as small as practicable.”
This should not be carried to the extent, however, of making the formation unwieldy. Four ships or fewer would be line abreast; six ships would be placed in four columns, the two middle columns having two each.
Column formation is to be avoided if possible while in the submarine zone, as it is relatively easy for the submarine to deliver a successful attack against vessels in column formation. There seems to be a general tendency for troop convoys to get into column on dark nights, or whenever the weather is the least bit unfavorable.
In order to make the destroyer escort most effective it is recommended that the interval be not greater than 800 yards. With a large interval the convoy is exposed to the danger of a submarine getting in between the columns. The wider front also weakens the ahead protection given by destroyers.
POSITIONS OF TRANSPORTS.
In all cases the most valuable vessels or transports requiring the greatest protection should be placed in the centre of the formation.
POSITION OF SUBMARINES.
The favorite position of the submarine for attack is from two to three points forward of the beam. This sector should always be carefully guarded.
In general convoys should be manoeuvred to pass clear of submarines directly ahead on the course, provided the report of the submarine’s position is recent and reliable.
Experience indicates that stragglers from a convoy are in grave danger of being attacked, and convoys should be kept closed up even if speed is to be somewhat reduced to accomplish this. If one vessel suffers a large reduction in speed after entering the zone, it is likely that two destroyers will be detailed for her escort, so that the main convoy can continue at maximum speed.
INSTRUCTIONS FOR TRANSPORTS IF DESTROYERS DO NOT JOIN UP.
In the event that destroyers do not join up the convoy should continue on to destination. They should not split up but remain in convoy. The ocean escort in this case would continue on to destination and should take station zigzagging ahead of convoy. All vessels of the convoy should have definite sealed instructions how to make the destination in the event that they become separated from the convoy.
OCEAN ESCORT AFTER DESTROYERS JOIN UP.
If destroyers do not join up for any reason until convoy is well into dangerous water, the ocean escort, if unaccompanied by destroyers, should exercise judgment as to whether to risk returning through the zone alone or continue into port. The destroyer escort can furnish latest information of submarine activities and the state of the sea, weather conditions, time of day, etc. will assist in the decision. In doubtful cases the ocean escort should continue into port.
It may be necessary for the ocean escort at any time to continue through the zone with the convoy. After the destroyer escort joins up it is recommended that the ocean escort (cruiser) take station in line of one flank at standard interval, so as to give some protection to transports. It has been found disconcerting to the destroyers to permit the ocean escort to zigzag across the front of the formation, and it is believed better protection can be given to the convoy if the ocean escort takes position in the formation. For a large convoy to facilitate communications it may be necessary for the cruiser to take station as leader of the centre column. Any transports so displaced would drop to the rear.
RADIO COMMUNICATION AND RECOGNITION SIGNALS IN “BRITISH HOME WATERS”.
A separate letter covering this subject has already been forwarded to the Commander, Cruiser Force
It is recommended that a paragraph be included directing that G.M.T. be kept on all clocks when east of Longitude 20 W. and that all times referring to the rendezvous, arrivals, and so forth east of Longitude 20 W. be considered as meaning G.M.T. All allied vessels use Greenwich Mean Time in this area, and all intercepted signals, reports of submarines, and so forth are based on G.M.T.
All allied vessels in the zone keep G.M.T. and signals from the convoy, such as “Change course at 3:20” are not understood, as it is not known what time the convoy is keeping. In working with allied escorts there is danger of a collision especially at night, unless all signals refer to G.M.T.
It is the general practice in mercantile convoys to provide rendezvous not only for the next day but for the second day as well.
VESSELS TO BE SPOKEN.
It is recommended that the paragraph in reference (a) under this subject be amended by the following addition:-
“This should not apply while in zone unless it can be accomplished without altering formation, for it is undesirable to weaken the escort in submarine waters.”
POSITION OF MERCANTILE CONVOYS.
The convoy commander should be cognizant of the position of all mercantile convoys that have recently left the United States, so as to avoid collisions on dark nights.
Convoys should not zigzag on dark nights, in fog, or similar weather. When the convoy is in line abreast formation, and especially when under destroyer escort, zigzags using large angles should be avoided. In general, no zigzag should be used which gives an angle of turn of more than 45º. Several zigzags have angles which approximate 90º. These zigzags are not suitable for vessels in the convoy under destroyer escort, as there is grave danger of collisions if they are used.
CHANGE OF COURSE.
If convoys are to change course without signal after dark, the escort should be previously notified. A collision recently occurred at night in the escort, as the convoy changed course without notifying the escort in advance.
It is recommended that particular attention be paid to the rudder angle used in zigzagging, especially when vessels are large and in line abreast formation, so that all vessels will turn in approximately the same time.
It is recommended that time signals be made twice a day so as to give an accurate check on all clocks that are used in zigzagging. An error of a few seconds in turning may prove serious, especially with large high speed ships.
WM. S. SIMS.
Copy to Secretary of the Navy (Operations).”
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J. R. POINSETT PRINGLE
Chief of Staff,