Overfalls

Rough, broken or confused water produced when strong flow passes over an irregular seabed or meets another stream.

Overfalls commonly form near banks, shoals, ledges, headlands and abrupt changes of depth, where tidal flow is accelerated or disturbed. They can also occur where streams converge. The surface may become steep and chaotic even when nearby water appears moderate.

Conditions are often most severe around stronger stages of the stream and when wind opposes the flow. Passage planning should consider tidal timing, wind, water depth, the charted warning and the vessel’s size and handling; avoiding the strongest flow may be prudent for a small or vulnerable craft.