A spokesman for Brittany Ferries said the vessel made "heavier than usual contact with the berth" Saturday morning, December 15. As a consequence the ferry's vehicle door "could not immediately be opened".
Travellers who had already gone down to Armorique's car decks were asked to return to the guest lounges "for their own comfort."
The company apologised to all customers who had been affected.
Brittany Ferries' Armorique ferry carries up to 1,500 travellers and 470 cars.