Ferries come in all shapes and sizes to fit the crossing that they are employed to do. Car ferries are usually based upon the ro-ro principle, so that vehicles can be driven on and off with relative ease. A common type of ro-ro ferry will have both bow and stern opening doors. Some designs, usually found operating in sheltered coastal waters may not have an apparent bow or stern and can operate equally well in either direction.
A recent trend is to operate on longer routes, fast ferries. Modern mainly catamaran, designs are currently available up to 127m in length which can carry 1600 passengers and 375 cars at over 40 knots. This enables the operator to offer more frequent services to their customers, although these high speed ships are limited by the number of vehicles that they can carry and also by the state of the weather and sea.
The large open deck area enables large numbers of passengers to be accommodated in comfort. Propulsion Machinery is located in each of the twin hulls and waterjet propulsion is used.