Turning basin

A turning basin is a widened water area where a vessel reverses heading to enter or leave a berth, sized so the design vessel can swing within it. For an unaided turn the basin diameter is commonly 2 times the vessel length overall, reducing to about 1.5 times LOA where tugs, thrusters, or favorable current assist, and to roughly 1.2 times LOA for a tightly tug-assisted swing. It is placed near the berths it serves, with depth equal to the channel depth so the ship stays clear of the bed throughout the turn. ROM 3.1 and PIANC give the sizing rules, adjusted for wind, current, and the assistance available.