Replenishment ships follow commitments

How many fleet replenishment assets should a navy have per number of frigates or destroyers?

Replenishment demand follows forward stations and commitments, not a fixed escort ratio.

A fixed replenishment-ship-to-escort ratio misses how navies operate. A large navy staying near home can need fewer auxiliaries than a smaller force maintaining distant stations. Forward commitments require ships to remain on station, replacements to take over, and enough support to sustain them. Auxiliary requirements therefore fall when commitments decline, rather than automatically following cuts in combatant numbers. Replenishment at sea also preserves freedom to maneuver and reduces dependence on allied support. The captains described here generally prefer to keep fuel above roughly one-third to one-half capacity, with arrangements for resupply beginning before that margin becomes restrictive. Around 60 percent is offered as an illustrative point to start arranging replenishment, rather than a universal rule.