marine fender

marine fender is a bumper used to absorb the kinetic energy of a boat or vessel berthing against a jetty, quay wall or other vessel. Fenders are used to prevent damage to boats, vessels and berthing structures. Fenders are typically manufacturered out of rubber, foam elastomer or plastic. Rubber fenders are either extruded or made in a mould. The type of fender that is most suitable for an application depends on many variables, including dimensions and displacement of the vessel, maximum allowable stand-off, berthing structure, tidal variations and other berth-specific conditions. The size of the fender unit is based on the berthing energy of the vessel which is related to the square of the berthing velocity. Historically, fenders were woven from rope in a variety of patterns. Fenders of woven rope are still used today by historic boat owners. Yachts, small leisure craft and support vessels typically have mobile fenders which are placed between the boat and the dock as the boat approaches the dock. Docks and other marine structures, such as canal entrances and bases of bridges, have permanent fenders placed to avoid damage from boats. Old tires are often used as fenders in such places.