Also try reducing the surface clutter and the gain, try to get a clear picture between surface and bottom, the best way to do this is set the range manually at twice the depth of the water you are in, and adjust the gain so that you see a second bottom line i.e. 30ft known depth, show two bottom lines one at 30 and another at 60., if you set the range at 90, you only want the 30 and 60 to show.