Reserve fleets preserve useful second-line ships

What happens when ships become outdated while sitting in reserve?

They remain available for secondary roles until newer reserve ships replace them, after which the oldest hulls can be discarded.

Fast technical change did not instantly make every older hull useless. Navies normally moved newer inactive ships into reserve and discarded the oldest generation only when replacement capacity arrived. Pre-dreadnoughts could still escort convoys, bombard shores, and perform other tasks that did not require battle-line equality. Reserve policy therefore treated obsolescence as a gradual reassignment of roles rather than an automatic reason to scrap a serviceable ship.