Furuno GP1971 Airmar TM185M interference

Mesut Dagli

New member

I have a small boat equipped with Simrad GO9 as chart plotter and Furuno GP 1971 w/ Airmar TM185 as fish finder.
I was having motor interference/noise on the screen, loosing dept etc at Furuno while my outboard is running, in the mean while it was connected to starter battery.
Then I moved both to the house battery where all the DC loads (12V) are including motor guide, this time Furuno is having the same issue when trolling motor is on.
With this set up, if I switch of both, Motor Guide and Suzuki than I have perfect screen.

Would you be so kind to advise, whether anyone have similar issue, any suggestion.


Johnny Electron

Staff member
RF noise can be either electrical for acoustic. I would recommend connecting the fish finder to a standalone battery (not connected to anything else) for testings. If the noise still happen it is acoustic noise not electrical. The best way to deal with electrical noise is to ensure everything has been properly grounded, including the GP1971F. The shield wire of the power cable is designed to be connected directly to a bonded ground system. If that shield is connected to something else or left open it can act as a conduit for noise.