A trailer broke free of its chains and toppled on top of five cars on board the NorthLink ferry Hrossey as she approached Shetland on Monday morning.
Three of the vehicles were badly damaged when the triple-axle trailer, which had been filled with sand before being taken on-board the vessel in Orkney, toppled shortly before 6am eight miles south east of Sumburgh.
No-one was injured in the incident, and the ferry did not have to delay its arrival in Lerwick.
However the owner of one of the cars crushed said he was surprised the ferry had sailed at all in such stormy conditions.
The vessel had been battling against fierce westerly winds, with occasional gusts of up to force nine, before the accident took place.
Alan Tait, from Stenness in Orkney, heard shortly afterwards the rear end of his Renault Laguna had been crushed by the trailer.
“It was about six in the morning when they had a big lump of water and the trailer broke loose. The front of the trailer landed on my back door and caved it all in. It will be a write-off.
“When we came here we weren’t allowed down to the car-deck, and then they announced it on the tannoy and everybody who had had a car damaged was taken to the side.”
Mr Tait, a farrier blacksmith, has come to Shetland to shoe horses for a few days.
He said he “didn’t really feel anything at all”, but became aware of a sudden surge which had clearly sparked the incident off.
“We’d been watching the weather and we were thinking it would have been cancelled. There was a lot of wind in Orkney throughout the day, but we assumed it was safe to come. My alarm went off at 6am and I thought it was too rough to get up.”
He said he had spoken to two other car owners whose vehicles had been completely flattened by the falling trailer. “I spoke to one lady who was very upset by it.”
A spokesman for NorthLink said: “A trailer carrying sand on board the Hrossey appears to have toppled just south of Sumburgh and a number of cars were damaged.
“The incident happened eight miles south east of Sumburgh, where there was a westerly wind force seven to eight, occasionally gusting force nine.”
The accident on board the Hrossey is just the latest in a number of incidents to have taken place on NorthLink ferries.
Only last week a passenger and Hrossey crew member were injured during a choppy crossing between Aberdeen and Lerwick. Both men were taken to the Gilbert Bain Hospital in Lerwick for treatment.
Earlier this year Hjaltland suffered a damaged door when she was hit by an abnormally large wave south of Mousa.