Calais-Dover ferry traffic was disupted on Saturday after more than 100 migrants stormed the port and tried to board a DFDS ro-pax.
About half of the group managed to make it on to the 34,000-gt Cotes Des Dunes (built 2001) at Calais, with some climbing on to the funnel.
Two more fell into the sea and were rescued.
More than 60 people were arrested after searches of the ship.
The migrants used a maintenance ladder to clamber aboard the ferry at high tide, according to a local authority official cited by the Daily Telegraph.
Searched took all night and at least two ferries had to wait offshore.
