A watertight part of the ship forebody that can be opened to provide clear access to the bow ramp. Bow doors are used on ro-ro ferries to enable handling of freight on drive-through basis; vehicles enter over the stern ramp and leave through bow ramp, thus speeding up turn around time. Two types of bow doors are in use: bow visor and the safer clam-type bow door.
- Bow visor – A single element connected to the hull by hinge arms and operated by means of hydraulic cylinders. The bow visor forms an integrated part of the bow structure and is equipped with sealing, hinges and cleats. In its open position it is rotated up to 90° to give clearance to the vessel own bow ramp.
- Clam-type bow door – A side opening twin-section bow door. Each section is attached to the hull by hinge arms which ensure parallel movement when opening or closing. The sections are swung outboard port and starboard by double-acting cylinders.
- Side Shifting Bow Door – A patented invention by TTS Ships Equipment. The door consists of two box constructions that open to either side of the door aperture by means of two guide arms mounted above the door opening. During opening of the door, the two sections are manoeuvred horizontally sideways and perpendicular to the ship centreline. Two double-acting hydraulic cylinders are used to operate each section. Weather and sea forces act perpendicularly all round the periphery of the door on the sealing system so that hinges or their bearings are not affected by any forces. A further advantage is that, as there are no manoeuvring devices in the region of the door structure, it can be built stronger and more effectively.