Vice Admiral William S. Sims, Commander, United States Naval Forces Operating in European Waters, to All Commanding Officers, United States Naval Forces Operating in European Waters
U.S. NAVAL FORCES OPERATING IN EUROPEAN WATERS
U.S.S. MELVILLE, Flagship.
30, Grosvenor Gardens,
London, S.W. 1.
14 January 1918.
From : Force Commander.
To : All Commanding Officers.
Subject: Stopping to make sound observations on enemy submarines.
1. In view of the recent developments of sound detection devices which enable a stopped vessel, with all auxiliary machinery stopped, to obtain bearings on submerged submarines at distance up to ten miles depending upon the speed of the submarine, it seems likely that all destroyers and patrol vessels will be equipped with them as soon as the devices become available in sufficient quantities.
2. In order to determine whether or not destroyers could be stopped without injury to machinery and auxiliaries certain trials have been conducted in the Mediterranean, from the report of which the following extract is quoted for your information.
“The following is an extract from a report by the Captain-in-Charge, Mediterranean Hydrophone Flotillas, to the British Commander-in-Chief, Mediterranean, relative to Hydrophone trials carried out in H.M. ships “Colne” and “Acorn”:-
(1) Object of Trial.- To determine if all machinery in oil and coal burning destroyers can be stopped sufficiently long to obtain a bearing with a portable directional hydrophone without damaging the machinery, and at the same time retaining sufficient power to attain a speed of, say, 15 knots within a few minutes of starting up.
(2) Weather.- Weather conditions were very unfavorable. Wind 4 to 5; sea, 4, with a heavy swell, causing considerable motion in the destroyers, especially when stopped.
(3) Target Vessel.- Motor Launch No. 162.
(4) “Results obtained:-
A.- H.M.S. “Acorn”.
0 00 - Engines stopped and ordered astern.
1 00 - Hydrophone down.
3 10 - Bearing obtained.
4 30 - Engines ordered ahead.
The above was repeated five times.
On one occasion all engines except the circulator were stopped for 24 minutes. Steam pressure when the engines were stopped was 200 lbs., and when engines started again 120 lbs. The circulator was stopped for three minutes, and in the opinion of the Engineer Officers could be stopped under similar conditions for five minutes. Time taken to stop all machinery from the order to stop was about one minute.
B.- H.M.S. “Colne”.
0 00 --Engines stopped and ordered astern.
0 45 - Hydrophone down.
3 15 - Bearing obtained.
5 00 - Circulator started.
This was repeated four times.
It was found possible to keep all engines except the circulator stopped for a period of 15 minutes. The circulator was stopped for five minutes, run for five minutes, and again stopped. This was repeated several times without any undue heating of the condenser.
Owing to the heavy seas running and the motion of the vessel during the trials the bearings obtained were not good, but were better than were expected. A speed of not more than 12 knots was ordered after stopping on account of the heavy seas running.
These trials prove conclusively that a destroyer can be stopped sufficiently long to obtain bearings with portable directional or plate hydrophones.”
/s/ WM. S. SIMS.