A Coast Guard investigation found that a fire believed to have started in the engine room of the M/V Melissa Ann over Labor Day weekend was actually steam from an overheating generator on the ferry. 

The 172-passenger Melissa Ann — Kitsap Transit’s backup ferry on the Kingston-Seattle route — was sidelined earlier this week after what was assumed to be a fire forced passengers and crew to evacuate Saturday afternoon.

When investigators from the Coast Guard and Kitsap Transit pumped the ferry’s bilge Wednesday, they found a problem with the vessel’s cooling system, Kitsap Transit executive director John Clauson said. 

The ferry pumps cold seawater into a heat exchanger that helps keep the engine coolant cool, Clauson said. On Saturday, a pipe used to carry the seawater disconnected from the heat exchanger, causing the engine to overheat and water to flood the ship’s hull. 

The steam from the overheating generator looked like a fire to crew members and passengers. 

“This would be like losing your fan on your radiator,” Clauson said. 

Fast ferry sailings between Kingston and Seattle were canceled again Wednesday, since Kitsap Transit’s primary ferry for that route, the M/V Finest, was also out for repairs. After running sea trials on Tuesday, the issues with the Finest appear to have been resolved, Clauson said. Fast ferry service from Kingston will resume Thursday morning using the Finest. 

The Melissa Ann is scheduled to be repaired and undergo sea trials this week, Clauson said. It could be put back into service as a backup as early as the end of this week.