Hi Skaguy: Many thanks for the information. I goes part way towards what I was looking for but seems to be confined to the vertical profile of current speed. It is also, based on my study of currents, somewhat missleading. The gradient from top to bottom is much steeper with a more abrupt change near to the bottom and a more gradual decline at levels above the bottom foot of water.
There is of course also a well defined horizontal pattern to current speed which declies towards the edges of the channel but is influenced by the meander patterns of the channel as well as by various obstructions which occur along the shore lines.
It is when you bring together the horizontal pattern with the vertical pattern that you begin to see the true variations in current which influence the fishermans cast. Along with this we have the influences of variable current on the float movaing at surface speed and the weight and bait moving under the influence of the bottom current speed. and indeed the interaction between the two with the float pulling the weight while the weight holds back the float.
It would be obviously impossible to know or visualize all the opposing forces involved nevertheless we need to synthesize all of this complexity if we are to fish intelligently.
Our ability to modify the behaviour of our float and bait is confined to being able to feed or slow the feed of line from our reel and to modify the direction of travel by use of the rod tip. Long rods and free turning reels are a great help in this but the ability to visualize the current forces involved can be our greatest asset.
If you locate any other sites which provide information ;please pass them on to me I shall do likewise.
coot