Tidal window

A tidal window is the period during which the tide gives a deep-draft ship enough water to transit a channel or enter a berth with adequate under-keel clearance. It is computed from the tidal curve, the charted depth to chart datum, the ship’s draft, and the dynamic allowances for squat, heave, and uncertainty. At depth-constrained ports the window may be only an hour or two each tide, so arrival timing and dynamic UKC management directly set how much cargo a ship can load without missing its window.