You're in a tiller boat idling along at about 1.5 mph. You could be using nothing but your trolling motor, or your engine. Either way the boat is not moving fast, maybe even less that 1.5 mph. The depth finder indicates that you just ran across a brush pile for which you have been searching. The image has not even made it a third the way across the screen, but that has to be it! You take out a marker buoy and toss it behind you. Question is......how far? I have not read anything here about image delay relative to speed relative to distance traveled after the image first appears, much less one third across the screen. Anyone have any tips? Thanks