The Navy has experienced chronic delays and labor overruns in maintenance on its large conventional ships (that is, ships that are not nuclear-powered). Those delays can affect deployment schedules and limit the operational readiness of the Navy's fleet. In this report, CBO analyzes maintenance events for two types of such ships—destroyers and amphibious warfare ships—from October 2010 to September 2024.

CBO finds that maintenance for large conventional combat ships often takes longer than expected. Schedules for overhauls underestimate their duration, and changes to those schedules have not closed the gap. Maintenance delays are driven by many factors.