A large wave struck a commercial ferry bound for North Haven on Thursday morning, knocking two heavy trucks onto a railing and leaving the vessel listing dangerously to its port side.

The 91-foot Island Transporter was one mile past the Rockland breakwater at 9:30 a.m., the Coast Guard said. The seas were about 6 feet but grew to 10 feet as the ferry headed into West Penobscot Bay. Then an even larger swell hit, knocking the trucks – one of them hauling cement and the other loaded with forms for molding concrete – up against the port rail.

“It was rough. They were lucky they didn’t roll over and all drown,” said North Haven Harbormaster Foy Brown. “They said it’s a wicked sea on. It’s been no’east and now so’east all week and it kind of builds up.”

Brown said the island’s passenger ferry canceled trips on Wednesday and Thursday because of the rough weather.

The Coast Guard dispatched the cutter Abbie Burgess, which was in the area, and the 175-foot buoy tender ran alongside the ferry, shielding it from the wind and the worst of the waves.

Over the next two hours, the ferry limped into the Fox Island Thoroughfare between North Haven and Vinalhaven islands, and eventually docked at North Haven.

“When I saw it coming through the thoroughfare, it looked like the boat was sinking it was tilted to one side so bad,” said William Trevaskis, a photographer who watched the ferry come in from his second-floor office near the dock on North Haven. The captain appeared to be struggling to maneuver the boat.

“It tried to make a pass into the ferry terminal landing and didn’t quite make it,” Trevaskis said. “It did this strange U-turn, headed toward Vinalhaven for a while, then came back.” The ferry was finally able to tie up.

A boatyard crane was used to right the form truck, which was carrying the forms and a mechanical boom for placing them. But workers were unable to right the cement truck. Brown said the large metal cement-mixing drum had come apart from the truck chassis and the cement inside had hardened.

Crews planned to return Friday with a scow and a large derrick to attempt to right the cement truck, Brown said.

The cement, supplies and equipment were to be used by a local carpenter working on a building project on North Haven, Brown said.

Nobody was injured, the Coast Guard said. The extent of damage had not been determined, but Brown said the toppled vehicles did not do significant damage to the boat.

David Hench can be contacted at 791-6327 or at:

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Twitter: @Mainehenchman