In most door access designs two watertight closures will be considerate adequate. Bow doors or a bow visor are the two options for the opening. Bow doors can be of parallel stow type (or swing-arm type), clam-type, directly-hinged typ, side-hinged or wing-type.
Bow access requires, by regulation, the highest degree of integrity. Some ships have three successive barriers to water ingress. In most designs two watertight closures will be considered adequate. When the bow ramp is in its stowed position, it is utilised to double as the inner door and this seals the aperture in the collision bulkhead.
It is divided in two or more sections, for example two main sections and an additional folding section with tapered end flaps. When deployed, the bow ramp provides access from main deck to the shore. When closed and secured, it forms a weathertight door at the collision bulkhead.
MacGregor side-swinging bow doors and bow ramp.