tidal flow

[timv]

A harbourmaster recently advised me that around the Plymouth area near the coast the ebb tide flows westerly and the flood easterly even though my tidal atlas shows the turn of flow about three hours later than this , he said this was more main channel . Would anyone local agree with this , it would explain some of my rougher than expected passages ?

many thanks for any advise
Tim

 

[Alan ashore]

I suggest this is a matter of terminology, not local knowledge. In this context "flood tide" is not the same as "rising tide", nor ebb the same as falling.
The stream reverses at the time the tide stops flooding and starts ebbing at a particular place, IMHO by definition of the terms. (*)
This will in general not be the time of High Water at that place, or indeed at the place used as a reference for the tidal atlas, diamonds etc.

(* in some places the stream does literally slow, stop, and reverse direction. In others it actually swings slowly all the way round in direction)

 

[LittleSister]

A harbourmaster recently advised me that around the Plymouth area near the coast the ebb tide flows westerly and the flood easterly even though my tidal atlas shows the turn of flow about three hours later than this , he said this was more main channel . Would anyone local agree with this , it would explain some of my rougher than expected passages ?

many thanks for any advise
Tim

As the 'incoming' tidal flow comes in from the Atlantic and floods up the channel towards (roughly) Dover (where it meets the flood that's come the other way round Scotland and down the North Sea), by definition the flood is heading east, and the ebb is heading west. What time it changes direction doesn't affect that at all.

I imagine is that what you meant, though, was that the tide changing from flood to ebb didn't coincide with the time of local high water. High water is only indirectly linked to the direction of flow (and depends on your location). As I see it, the tide is something like a very long shallow wave of water passing up the channel. High water at, say, Plymouth is when the peak of the wave is passing by, but the flow continues in the same direction for a while after it has passed, contributing to the height of the back of the wave. The flow then turns and heads the other way to build the front of the next wave approaching.