Logistics ships depend on where a navy intends to fight

How many replenishment ships does a navy need to sustain credible combat operations?

For a carrier group, roughly two stores ships and two tankers; fleet-wide numbers depend on operating distance and political ambition.

The example carrier group has at least two solid-stores ships and two tankers. One of each can return for replenishment while the other pair sustains the group, with the warships' own stores providing further coverage. A force operating near its base can return there for supplies, whereas a force across the world from its industrial base needs more support afloat. The number of auxiliaries therefore follows the intended operation and distance from support. The discussion criticizes buying fewer ships while continuing to demand the original level of activity. It also sets a minimum for an additional useful hull: more than seven days at sea, an ocean-crossing capability, and viable self-defense.