Im no specimen hunter so excuse me here but ive always wondered how carp and pike anglers know about the underwater features in a venue. I hear them talking about gravel bars, plateaus, patrol zones etc, some of which are maybe 30 or 40 yards out. Now I gather most of this can be found out by using a fishfinder but I cant believe everyone uses this method. I can find features when float fishing obviously by using a plummet so whats the technique when fishing at distance? Do you count the lead down on casting and estimate the depth repeatedly over your swim?

Use a marker float which is best tied to the end of braided mainline with a running ledger.
There are specially designed leads to help you FEEL the bottom.
Cast as far as you can and wind float down to lead.
Let out a foot of line at a time to get depth.
Once known wind float back down to lead and drag lead with a side ways sweeping of the rod.

If the bottom is silt the lead glides through smoothly, gravel causes a tapping sensation and weed causes tugging or a complete lock up!!!

Now let out line a foot at a time to get depth etc etc etc.

It sounds complicated but is easy after a short amount of practice.

It is best to draw an underwater map of your peg and keep it.
Next time you fish the peg you can use for referance to maximise angling time.

Thanks Rudd. Just found this http://www.anglersnet.co.uk/authors/gaffer01.htm on the subject too.