A Thomaston contractor is suing a private ferry operator over equipment losses and emotional distress caused in December during a rough crossing in Penobscot Bay.

Sawyer Brothers Inc. filed a lawsuit Aug. 20 in U.S. District Court in Portland against the owners of the Rockland-based ferry M/V Island Transporter. The vessel is owned by Island Transporter LLC.

Ross Sawyer, president of the Thomaston company, and Ryan Sawyer, vice president, allege in the civil suit that the ferry was hired to transport a boom truck and load of concrete panels on Dec. 11 to North Haven, but that its captain was negligent because he failed to heed weather warnings issued by the National Weather Service.

In addition to Sawyer Brothers’ equipment, the suit alleges that a fully loaded cement mixer – not owned by Sawyer Brothers – was allowed to board the ferry.

The company alleges that as the ferry approached open water off the Rockland Breakwater, the vessel began to “roll violently” as waves poured over the deck.

“Ross Sawyer became delirious with fright” when he saw the boom truck begin to slide across the deck, the lawsuit said.

It said the boom truck tipped on its side, causing equipment to slide into the ocean, and that the truck was damaged beyond repair. The cement mixer also tipped over, causing the vessel to list in rough seas. A Coast Guard vessel and the North Haven ferry of the Maine State Ferry Service escorted the ferry to North Haven.

The lawsuit asks for damages of $165,000, plus interest and costs.