Monday, January 7, 2008


Tidal Currents
There are several different kinds of currents including oceanic, river, and wind-driven all with their own driving force.
Tidal currents (a horizontal motion) are a result of the rise and fall of the water level due to tides (a vertical motion). The effects of tidal currents on the movement of water in and out of bays and harbors can be substantial.

The set of a current is the direction that it flows toward. Note that this is the opposite of the way winds are reported.
This is the speed of a current, on ocean waters it is usuallly stated in knots, in rivers, mph.
This is an indication of both speed and direction (set and drift).
How fast the water is moving in relation to a stationary object.
Flood Flow
The tidal current is in flood when it is coming from the sea to the shore (tide is coming in, or high tide is.
Ebb Flow
The tidal current is in ebb when it is coming from shore and returning to the sea.
Slack Water
The point between flood and ebb (or ebb and flood) currents when there is no horizontal movement.
The point where vertical changes stop as the tide reverses. This is not the same as slack water, this is a tidal (vertical), not a tidal current (horizontal).
Maximum Current
The normal maximum speeds of the ebb and flood currents. This does not include effects of weather or run off from rain or melting snow, which can effect tidal currents.