While fishing today, I started getting some interference from the trolling motor (2015 PDV2 Saltwater). It has never done this in the past. It starts getting real bad on 2d and goes from the bottom up to about 15' below the surface. It is obvious that's what it is, and it instantly goes away when the motor is stopped. I left it stowed away out of the water and turned it on, it had no interference at that point. I guess something in it may be getting worn causing it all of a sudden. The graph is direct wired to the cranking battery in the rear of the boat, and the trolling batteries are in the CC. The wires from the trolling motor run from the CCto the front, and the transducer cable from the CC to the rear. They are 19" apart at their closest point. The battery charger is the only common link that I can think may be doing this. I'm going to unhook the cranking battery and see what happens. Any other suggestions or experience with this?

Mine started having rfi and it was the water intrusion, the brushes had water and rusted. I can also tell from experience to do all the testing while boat is in the water. The water adds another grounding element that you don't get on the trailer.