I have a issue with my HDS with "interference" on the screen but only when it gets a little bumpy out. When it's dead calm it runs perfect. It stops marking my deepest downrigger also - if not both when this happens. By interference I mean vertical lines from top to bottom on the screen. It happens in auto or in manual mode where I can control sensitivity,ping speed and color line. I have a Starcraft islander and I installed it last year. I put the transducer in the same spot that my last lowrance transducer was. Transducer location ? My settings seems to be spot on. Any suggestions appreciated before I start drilling needless holes- Thanks