Outer harbour

An outer harbour is the part of a port outside the inner basins, formed by breakwaters to give a first stage of shelter and a transition from the open approach to the protected berths. It holds the approach channel mouth, anchorage and waiting areas, and often the turning basin, and absorbs the wave energy the breakwaters intercept so the inner harbour stays calm. Layout fixes the entrance width and orientation to limit wave penetration and cross-current at the gap while leaving room for vessels to enter and swing. Pilot boarding, tug assembly, and quarantine or layby berths commonly sit in the outer harbour before a ship moves to its inner-basin berth.