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#12342659 - 07/16/17 02:09 PM Trolling motor interference with Bow Mount Finder
Bill Durham Offline

Registered: 11/10/12
Posts: 472
Loc: Crowley

There was a recent thread about this and it tweeked me to fix mine. I have a Hummninbird 759CI on the bow and a Motor Guide GW80 trolling motor. The power for my Finder comes from the first of the 2 batteries used for the trolling motor.. fed to the front of the boat by the 3rd big wire run for the twist lock connector mounted in the boat. The first battery provides the ground connection for the trolling motor so the finder gets ground from that battery as well. The interference happened everytime I turned on the trolling motor.. a big spike on the screen than a masking type of interference. I know that is the worst possible hookup for interference.. so its with great joy that I report that I fixed it!
The fix was adding shielding to my power cable. The power connection for the finder comes out of the back of the twist lock connector for the TM. My power cable for the finder is about 4' long. Its a 2 conductor unshielded cable provided by Humminbird and I was able to cover that cable with a tinned copper shield cable and terminate that shield to the ground connector in the twist lock. Like everybody else, I had cable tied the transducer cable to the TM power cable.. so I separated those cables as well. The interference is gone! I am a happy camper!

Braided wire shield cable can be bought at Its a pain in the butt to push the wire through the braid.. if you had to do something longer than the 4' I will need some kind of messenger cable to push through the braid first and then pull the power cable back through.

Good luck

#12342766 - 07/16/17 03:20 PM Re: Trolling motor interference with Bow Mount Finder [Re: Bill Durham]
stxrippinlips1 Offline

Registered: 04/17/16
Posts: 140
Loc: San Antonio, Texas
You need to wire the graphs independently to the cranking batteries, ground cranking battery to last trolling motor battery, and lastly do not run your transducer cable down the trolling motor head power wire that goes to your foot pedal, instead run it down the frame of the trolling motor mount that mounts to your boat. I think if you run your power to the cranking battery you should solve the issue. Also make sure the fuse in the head of the trolling motor is intact, and ground your trolling motor. Try these suggestions should work, it did work for me and my birds. I still get erratic depth readings for some reason in 8ft or less of water for some reason, trying to figure this one out still!

#12344815 - 07/17/17 07:11 PM Re: Trolling motor interference with Bow Mount Finder [Re: Bill Durham]
Bruce Allen Online   content
Extreme Angler

Registered: 06/11/06
Posts: 2218
Loc: Lake Fork, Texas
stx it might be the frequency you are running
Lake Fork Anglers
Faze 4 Bass Anglers: Team Competition
Hard Core..Major League Fishing format

Lake Fork Sportsman's Association

Contact me to schedule the LFSA Live Release Boat for your Lake Fork tournaments.


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