11.   Experts say these are uniquely susceptible to rapid capsizing and sinking, due to their vast, open-plan vehicle decks.

12.   The vehicle decks of ro-ro ferries make them economically attractive for their easy drive-through access to big lorries.

13.   The vessels are characterized by their vast, open-plane vehicle deck, close to the water line.

14.   Under the Danish proposal, roll-on roll-off ferries should be able to handle a specified amount of water on the vehicle deck without sinking.

15.   Moreover, the lorries and private cars were not properly secured on the vehicle deck, he said.

16.   Rail ferries are boats with railway lines on their vehicle decks.

17.   The International Maritime Organisation has recommended building water-tight compartments on the vehicle decks to stop the ship keeling over in the event of an accident.