In-Service Vessel Sustainment Program

The ISVS program is part of the Coast Guard’s long-term recapitalization and sustainment strategy for the in-service fleet of cutters.

It consists of two kinds of projects:

• Major maintenance availability (MMA) – Planned life cycle events for targeted work and recapitalization of obsolescent/unsupportable systems, necessary for the cutter to achieve its design service life. MMAs facilitate fleet maintenance and increased availability for missions during a cutter’s later years of service. Shifts in the cutter’s homeport and assigned crew are considered in the planning process.
• Service life extension program (SLEP) – Addresses specific systems and major maintenance to extend the service life of the vessel beyond the original design service life. A SLEP is not designed to increase a ship’s capability; it only extends the service life of the cutter by replacing obsolete, unsupportable or maintenance-intensive equipment and by seeking standardization of configuration issues.

Current ISVS projects:

• 270-foot medium endurance cutters SLEP involves targeted system replacement to address system reliability, supportability, obsolescence and interoperability. This work includes upgrades or replacements to the electrical power generation and distribution system as well as the main propulsion engines. The mission is to facilitate continued operations during transition to the offshore patrol cutter by extending the service life of the cutters for up to 10 years. Work was completed on two prototype vessels at Coast Guard Yard before full production began in 2023. These vessels were commissioned from 1983 and 1991.

• 175-foot coastal buoy tenders MMA has started on the first of 14 cutters within the class. Coastal buoy tenders serve the Coast Guard in a variety of missions and are tasked with maintaining aids to navigation, search and rescue, law enforcement, alien interdiction, marine safety inspections, environmental protection and natural resources management. Keeper-class cutters are also used for light ice breaking operations. They were commissioned from 1996 to 2000.
• Coast Guard Cutter Healy SLEP has been initiated, with the five-year phased production scheduled to start in 2027. Healy is one of two Coast Guard medium polar icebreakers and a 420-foot cutter that was commissioned in 1999. When completed, the SLEP effort will recapitalize a number of major systems and extend the service life of the cutter until the polar security cutters are operational.
• 418-foot national security cutters (NSCs) MMA is in the planning stages to ensure the fleet maintains capability until the end of its design service life. The program will shift from the traditional single extended depot period to a heavy depot maintenance model, which will achieve a component-by-component refresh across the fleet. The NSCs were commissioned starting in 2008.
• 47-foot motor lifeboats (MLB) SLEP is being conducted in partnership with the Boats Acquisition Program to take advantage of the program's subject matter expertise, reduce support costs and improve operational availability. The service life extension work will significantly overhaul up to 107 of the 117 MLBs in the fleet. The fleet was placed in service from 1997 to 2003 with an expected service life of 25 years. The SLEP was initiated to extend the useful life of the MLB fleet by 20 years through 2047. The SLEP will reduce support costs and improve operational availability through renewal of the propulsion, electrical, steering, towing, navigation, and hull and structural systems, along with other minor work items.

• Coast Guard Yard
• Coast Guard Cutter Eagle

The In-Service Vessel Sustainment (ISVS) Program is the successor of the Mission Effectiveness Project, which replaced systems on the 210-foot and 270-foot medium endurance cutters and the 110-foot Island-class patrol boats to extend their operational lives until the arrival of new national security cutters, fast response cutters and offshore patrol cutters.

Cutter classes that have completed work under the ISVS program are:

• Coast Guard Cutter Polar Star underwent service life extension program work over a five-year period to recapitalize a number of major systems and extend the service life of the cutter until other polar security cutters became operational. The SLEP started in 2021 and was completed on schedule in 2025. Polar Star, a 399-foot cutter commissioned in 1976, is the service’s only active heavy polar icebreaker. 

• The 225-foot Juniper-class seagoing buoy tenders completed major maintenance availability work in 2025, ensuring the 16 vessels in the class achieve the full 30-year designed service life. Work included completion of hull and structural repairs and replacement of obsolete, unsupportable or maintenance-intensive equipment, including updates to the machinery control system, propellers and HVAC systems. The vessels were commissioned from 1996 to 2004.
• The 140-foot Bay-class icebreaking tugs completed service life extension work in 2020, restoring mission readiness and extending the service life of this nine-cutter fleet by approximately 15 years. Critical reliability and supportability issues had severely degraded mission readiness of the fleet, which was commissioned from 1978 to 1988 with a planned 30-year service life. Completed efforts include repair of corroded and damaged hull plating, structural refurbishment and replacement of unsupportable or maintenance-intensive equipment. Additional HVAC improvements were completed in 2023.