Originally Posted by Cane Pole
What you see on your display is somewhere within the view or cone but with a single beam transducer there's no way of knowing what side of the cone it is on. You can get an idea whether an object is moving from the center of the cone to the edge of the cone if the return is getting weaker as it tracks onto and across your screen and visa versa.
Humminbirds's dual beam transducer system is supposed to be able to differentiate between fish in the narrow beam or on the left or right in the wide beam.
If you're seeing fish that are 10-feet deep with a 20-degree transducer they are within about a 3-foot diameter circle so it's not too important where they are in the cone - they are right under your transducer.
When I get over a part of a brushpile that shows fish I'll throw a buoy marker just off to one side and up-wind of that area and then move the boat over and pull our baits to the area using the marker as a reference.
My clients often ask why they don't see any fish on the graph and I explain to them that we can only see what's directly under the boat and not what's in the area we are fishing even though our bait is only 10-feet from the boat.