Harbour basin

A harbour basin is the sheltered water area inside a port where vessels berth, sized and shaped for the design vessel and its berthing maneuvers. It sits behind breakwaters or in an impounded dock and provides depth equal to the vessel draft plus under-keel clearance, plus plan room for the ship, its fenders, and assisting tugs. Layout types include open basins, finger-pier basins, and tidal versus impounded basins held at a fixed level by a lock. Wave penetration is limited to operational thresholds, near 0.3 meters significant wave height for general cargo and tighter for sensitive cargoes, so basin orientation and entrance width are set to keep berths workable.