The periodic horizontal movement of water caused by the tide, as distinct from the vertical rise and fall. In channels and estuaries it reverses between flood and ebb; offshore it often rotates. Speeds range from barely measurable to over 10 knots in narrow passes. Current predictions are published separately from height predictions because slack and maximum current rarely match the times of high and low water.
Tidal current tops out at 4 knots under the bridge, so the tow waits for slack.
British mariners say tidal stream for the horizontal flow and keep tide for the vertical; mixing them on a passage plan marks a beginner.
Also heard as
- tidal stream
Related terms
Flood
Tidal current running in from the sea and up rivers and estuaries, mostly while the water is rising.
Ebb
Tidal current running out toward the sea and down rivers and estuaries, mostly while the water is falling.
Slack water
The short lull when a reversing current almost stops while it swaps between flood and ebb.
Reversing current
A tidal current that runs back and forth along one line, flood one way and ebb the other, with slack at each change.
Rotary current
An offshore tidal current whose direction keeps swinging round the whole compass during each tidal cycle.