The only old vessels of this type suitable for mining in enemy waters were ships of the "Ariadne" class, and although their machinery was not too reliable, two of these vessels that were seaworthy were converted to minelayers.

In addition a number of the older light cruisers were fitted with portable rails on which mines could be carried when minelaying operations were contemplated, in place of a portion of the armament which could be removed; a flotilla of destroyers, with some further flotilla leaders, were also fitted out as minelayers, and several additional submarines were fitted for this purpose.
For a projected special scheme of minelaying in enemy waters a number of lighters were ordered, and some of the motor launches and coastal motor boats were fitted out and utilized for mining operations on the Belgian coast towards the end of 1917.
By the end of that year 12 light cruisers, 12 destroyers and flotilla leaders and 5 submarines had been fitted for minelaying.

Two old cruisers had been added to the minelaying fleet and several other vessels were in hand for the same purpose.

The detailed plans of the arrangements were prepared and the work of fitting out minelayers carried out under the supervision of Admiral R.N.Ommanney, C.B., whose services in this matter were of great value.

The rapidity with which ships were added to the minelaying fleet was largely due to his efforts.
On the entry of the United States of America into the war a further development of mining policy became feasible.