Hi Fellars. I have a Garmin 172c chart plotter and a Garmin FF250 b&w. Ilove these guys and cannot fault them. I have always ran my fish finder in auto, thinking this was the best way. I have since read from another thread that the sensitivity should be set in manual and tweaked to suit the area targeted. For me in the Gladstone QLD area, this about the 40-45 metre depth. However i can not see a sensitivity link/button on the sounder. This function is possibly under another heading. If any one has a Garmin FF250 sounder, could you please instruct me on the correct manual set up procedure for more accurate reading. Would be much appreciated. Thanks and tight lines. Woodsy.