The Gibraltar convoy (an exception to the general rule) contained ships of only 7 knots speed.
With the introduction of convoys the provision of efficient signal arrangements became a matter of importance.

The issue of printed instructions to each master and the custom introduced of assembling the masters to meet the captain of the escorting cruiser before sailing, so that the conduct of the convoy might be explained, had the effect of reducing signalling to a minimum, but it was necessary that each ship should have a signalman on board, and the provision of the number of signalmen required was no easy matter.

A good wireless installation was essential in the escorting cruiser and in the Commodore's ship in order that the course of the convoy could be diverted by the Admiralty if the known or suspected presence of submarines rendered it necessary, and also for the purpose of giving to the Admiralty early information of the position of a convoy approaching the coast, so that the escorting destroyers could be dispatched in time.
Fortunately for us, German submarines constantly used their wireless installations when operating at sea, and as a consequence our wireless directional stations were able to fix their positions by cross bearings.
This practice on the part of the enemy undoubtedly went far to assist us both in anti-submarine measures and in diverting trade to a safe course.
The introduction of the convoy system rendered the provision of anti-submarine protection at ports of assembly a matter of great importance, owing to the very large number of vessels that were collected in them.

Some of the ports were already in possession of these defences, but amongst those for which net protection was prepared and laid during 1917 were Halifax, Sydney (Cape Breton), Falmouth, Lamlash, Rosslare (on the south-east coast of Ireland), Milford Haven, Sierra Leone and Dakar.

This involved extensive work, and was undertaken and carried out with great rapidity by Captain F.C.Learmonth and his staff, whose work in the production of net defences during the war was of inestimable value, not only to ourselves, but to our Allies, for whom large supplies of net defences were also provided.