In arranging the organization of the Atlantic convoy system it was necessary to take into consideration certain other important matters. Amongst these were the following:
1. The selection of ports of assembly and frequency of sailing. During the latter half of 1917 the general arrangements were as follows for the homeward trade:
Port of Assembly. Frequency of Sailing. Destination.
Gibraltar Every 4 days. Alternately to
E. & W. c'ts.
Sierra Leone Every 8 days. Either coast.
Dakar Every 8 days. Either coast.
Hampton Roads (U.S.A.) Every 4 days. Alternately to
E. & W. c'ts.
New York Every 8 days. Alternately to
E. & W. c'ts.
Halifax, N.S. Every 8 days. West coast.
Sydney (Cape Breton) Every 8 days. Alternately to
E. & W. c'ts.
Each port served a certain area of trade, and vessels engaged in that trade met at the port of assembly for convoy to the United Kingdom or to France.
The total number of merchant ships sailing thus in convoy every eight days in September, 1917, was about 150, in convoys comprising from 12 to 30 ships, and the total escorting forces comprised:
50 ocean escort vessels (old battleships, cruisers, armed
merchant ships and armed escort ships),
90 sloops and destroyers,
15 vessels of the "P" class (small destroyers),
50 trawlers,
in addition to a considerable force for local escort near Gibraltar, consisting of sloops, yachts, torpedo boats, U.S. revenue cruisers, U.S. tugs, etc.
At this period (September, 1917) outward convoys were also in operation, the arrangement being that the outward convoy was escorted by destroyers or sloops to a position 300 to 400 miles from the coast clear of the known submarine area, and there dispersed to proceed independently, there being insufficient ocean escort vessels to take the convoy on; about twelve more were needed for this work. The escorting vessels used for the outward convoys were destroyers or sloops which were due to proceed to sea to meet a homeward convoy, the routine being that the outward convoy should sail at such a time as would ensure the homeward convoy being met by the escort without undue delay at the rendezvous, since any long period of waiting about at a rendezvous was impossible for the escorting vessels as they would have run short of fuel. It was also undesirable, as it revealed to any submarine in the neighbourhood the approach of a convoy.
It will be realized by seamen that this procedure (which was forced upon us by the shortage of escorting vessels) led to many difficulties. In the first place the homeward convoys were frequently delayed by bad weather, etc., on passage across the Atlantic, and, owing to the insufficient range of the wireless installations, it was often not possible for the commodore to acquaint the Admiralty of this delay in time to stop the sailing of the outward convoys. Again, outward convoys were often delayed by bad weather, resulting in the homeward convoy not being met before entering the submarine zone. As the winter drew near this was a source of constant anxiety, since so many of the vessels outward bound were in ballast (empty), and their speed was consequently quickly reduced in bad weather. The ships under these conditions became in some cases almost unmanageable in a convoy, and the responsibilities of the escorts were much intensified.
In September, 1917, the following was the position in respect to outward bound convoys: