mines mounted up front and transducer is on trolling motor . check and make sure the transducer didnt move on the mount , it should sit parallel in the bracket . also check your settings on it and see how its set up in the settings screen . mine only does that when i get in shallow water and once i move out of that area it keeps reading right . i thought the same thing when i first seen it but i stuck my rod tip in the water it was pretty well right on what it was reading and had never read wrong on the screen ,hopefully that helped .