Encyclopedia of Marine and Energy Technology



Large steel constructions consisting of longitudinal beams plated over to provide a vehicle roadway. External ramps are used to allow wheeled vehicles to travel between a quay and a ro-ro ship; stern, side and bow ramps are used. Fixed or movable internal ramps provide access from deck to deck. For trucks and trailers, the slope angle of the shore ramps and the internal ramps between the decks must be kept below 8-9 degrees and the loading arrangement must be carefully considered. For roll trailers and cassettes, the slope angles should be less than 7 degrees.

External ramps – Usually stern ramps are used for loading and discharging of rolling cargo. Straight stern ramp, quarter ramp or slewing ramp can be used. If required, the ramp can also serve as a watertight door when pivoted or folded into its closed position.

Stern quarter ramp – Angled ramp, usually offset at an angle between 30o and 45o to the centre-line.

Slewing ramp – Stern ramp that can be set to an appropriate angle up to about 40o from the centre-line on either side.

Ro-ro vessels berthing at quays with considerable height differences require long ramps. To avoid stovage problem, foldable stern ramps can be used. The foldable stern ramp/door comprises two main sections articulated together and provided with outer and inner flaps to allow smooth transition of vehicles. When in the closed position, the inner section acts as a weathertight door, secured by hydraulically-operated cleats and locking devices.

Car carriers are additionally equipped with single-piece side ramps arranged in the side shell. When raised in its closed position, the side ramp forms its own weathertight door, and there is no need for any additional inner door.

Bow ramps are used on ro-ro ferries to unload vehicles. The bow ramp is usually an axial ramp linking the ship to the quay through a bow opening having a visor or side-hingedbow door.

Internal ramps – Fixed or hinged internal ramps are used for distribution of cars, trailers or cassettes within the ship. Hydraulically-operated steel covers are installed over fixed internal ramps. The ramp covers fulfil the same requirements for load carrying capacity and watertightness as the surrounding fixed deck. Depending on needs they can be either side-hinged or end-hinged.

Spiral ramp – A special ramp on the forecastle deck constructed for the first time by Gdansk Shipyard.

Tiltable ramp – The single-section internal ramp provided with flaps and hydraulicallydisconnected hinges at both ends. In this arrangement, the hinge at either its forward or after end can be secured to the upper of the two decks, allowing the opposite end to be lowered to the other deck. Raising/lowering is accomplished by a pulling cylinder/wire system.

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