Looking for ideas to track down this interference issue. Side imaging gets a washout effect when trolling motor prop is on. The photo shows a darker band which is the short interval I turned off the prop on the trolling motor to take the photo.
It is definitely electrical interference as evidenced by the immediate change when turning thrust on or off. There is no difference whether trolling motor speed is 1 or 10. It has nothing to do with the prop turning in the water as it does the same thing with the prop out of the water.
Minn-kota terrova 36v with 3 dedicated trolling batteries. Cranking/house battery powers everything else. The only physical connection between the trolling batteries and the house battery is the 4 bank pro mariner onboard charger. As those circuits are isolated, I wouldn't expect that to be the issue but I haven't tried disconnecting the charger leads.
The minnkota has US2, which I unplugged from the graph to confirm that connection was not the culprit.
The trolling motor power wires do not run anywhere near the transducer cable.
I am struggling to think of what else I can check. Any ideas or similar experience? Thanks.