Why carrier groups need deep tanker and stores-ship reserves

Could I be an RFA commodore?

An expanded Royal Fleet Auxiliary would need people as well as ships. The response proposes better pay, faster stores-ship construction, and a larger tanker fleet.

The question prompts a proposal to expand the Royal Fleet Auxiliary, agree a pay increase, and put more ships into service. The suggested baseline is four stores ships and eight to twelve tankers, before adding landing ships or other support vessels. A carrier group needs at least one stores ship and one tanker, preferably two tankers. The availability example assumes that four stores ships usually yield two available, while eight tankers yield four. That leaves some capacity for other duties and support to allies. Total hull numbers therefore need to include a contingency beyond the vessels required on deployment.