U.S. Coast Guard Icebreaking Tug, USCGC Thunder Bay Departs Coast Guard Yard Following Completion of its Service Life Extension Project

The U.S. Coast Guard 140-foot icebreaking tug, USCGC Thunder Bay (WTGB-108) departed Coast Guard Yard in Curtis Bay, Maryland on Dec. 11, 2018, after completing service life extension project as part of the In-Service Vessel Sustainment (ISVS) program.

Thunder Bay is the seventh of nine 140-foot icebreaking tugs to undergo service life extension work through ISVS. Work being completed to extend each cutter’s service life by 15 years includes upgrades to propulsion and electrical systems, replacement of the boat-launching davit and habitability improvements.

Thunder Bay will return to Rockland, Maine.

USCGC Thunder Bay (WTGB-108)

USCGC Thunder Bay is one of eight Bay Class Icebreaking Tugs presently in service with the US Coast Guard, and is homeported at USCG Station Rockland as a member of the US Coast Guard’s 1st District.

Thunder Bay entered service in 1986. Her overall length is 140 feet with a beam of 37 feet, displacing 662 tons.

Bay-class is a class of 140-foot (43 m) icebreaking tugs of the United States Coast Guard, with hull numbers WTGB-101 through to WTGB-109.

They can proceed through fresh water ice up to 20 inches (51 cm) thick, and break ice up to 3 feet (0.91 m) thick, through ramming.

All Bay-class cutters, including Thunder Bay, use a low-pressure-air hull lubrication or bubbler system that forces air and water between the hull and ice. This system improves icebreaking capabilities by reducing resistance against the hull, reducing horsepower requirements.

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