The vast majority of the Navy submarine maintenance has occurred at public shipyards over the last decade, which, according to a recent Government Accountability Office report found, has only gotten the job done on schedule 11% of the time.
There are four public naval domestic shipyards that provide most of the maintenance on attack submarines and other nuclear-powered vessels: Portsmouth Naval Shipyard, Norfolk Naval Shipyard, Puget Sound Naval Shipyard, and Pearl Harbor Naval Shipyard. From fiscal 2016 through fiscal 2025, those four facilities took longer than planned for 89% of the time to complete depot-level maintenance on attack subs, according to the GAO report, which was released on Thursday.
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The Navy incurred 3,040 days, or more than eight years, of maintenance delays from fiscal 2016 to fiscal 2020 and another 3,454 days, or nearly 10 years, from fiscal 2021 to fiscal 2025. The average depot-level maintenance period for a sub from fiscal 2016 to fiscal 20 was 744 days compared with 809 days from fiscal 2021 to fiscal 2025.
The delays have incurred an estimated $3.4 billion in costs to sustain crews and submarines during delayed maintenance and, without mitigation, could cost another $3.1 billion over the next five years. It’s also resulted in the loss of more than 15,000 operational days, and the service could incur roughly the same amount over the next half-decade.
“While the U.S. Navy has recently made some progress in reducing attack submarine active idle time, inactive idle time has grown and will continue to grow with the impending wave of Los Angeles-class inactivations over the next 5 years,” the report said.
The Navy has 44 attack submarines in its fleet. The plan the Navy uses for its submarine fleet, formally known as the Fleet Response Training Plan, calls for an 18-month operational plan: first, a 12-month training and certification process, followed by a six-month deployment. It’s technically a 19-month process in total because there is a 30-day stand-down period following the deployment.
Subs will go through this cycle three or four times before they must enter extensive depot maintenance, which could last between two and three years.
The maintenance delays have resulted in situations where a submarine’s deployment ends and one of the shipyards is not able to immediately start repairs. That in-between period is known as idle time for active submarines. The crews on board must remain pier-side because they are no longer certified to conduct normal operations, but it’s considered an active submarine because it’s not yet decommissioned.
From fiscal 2016 to fiscal 2025, the Navy incurred nearly 25 years’ worth of active idle time for active submarines. The annual amount of idle active time for subs hit its peak in 2022 with 1,518 days, or about four years, but has since declined significantly to 166 days in fiscal 2025.
There’s also idle time for inactive attack submarines, which is intended for when a sub is designated to be decommissioned but cannot be inducted into a dry dock in a public shipyard. For example, the USS Pasadena entered inactive idle status on Jan. 1, 2025, but is not expected to be decommissioned at Norfolk Naval Shipyard until November 15, 2028. The Navy is trying to use it as a training platform to train crews because it still has to be fully crewed. This delay will cost the Navy over $300 million over the nearly four-year inactive period.
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There are two private shipyards — General Dynamics Electric Boat at Groton, Connecticut, and Huntington Ingall Industries Newport News Shipbuilding at Newport News, Virginia — that build nuclear-powered ships, attack submarines, and provide a small amount of depot maintenance for them as well.
“The private yards have a very poor track record on the few occasions the Navy sent depot maintenance their way, worse than the public yards,” an official familiar with the report told the Washington Examiner. “Private yards are built & staffed to build subs, not maintain them.”
The GAO report made two recommendations to the Navy: the secretary should ensure the Chief of Naval Operations directs the Naval Sea Systems Command to evaluate alternative options for decommissioning attack submarines more efficiently to allow for operational subs to receive faster maintenance and to develop and implement a plan for attack submarine inactivations that reduces inactive idle time for crews. Navy officials “verbally concurred with the recommendations in this report, but did not provide written comments.”
