Bulkheads are vertical partitions or walls. All ships must have a specified number of bulkheads, depending on their length. By dividing the ship into watertight divisions they reduce the danger of sinking if one compartment is holed. They also reduce the risk of fire spreading. The forward bulkhead, called the ‘collision bulkhead’, is made particularly strong as it would have to withstand considerable buffeting if the ship steams to a repair yard having had her bows severely damaged in a collision. One of the problems of Ro/Ro ferries has been the large undivided car deck spaces which make them very vulnerable to flooding and to the subsequent loss of stability.