2018 Skeeter with Fortrex TM. 36V system...3 batteries. All connections tight. Are the pics below electrolysis and if so, how do I fix? The skeg on my trolling motor is missing some of the black paint and is where you can now see the white. The other pic is the outer edge of the built-in transducer on trolling motoir.

Getting any on the big motor or prop?

Most likely it is, you need to make sure that your cranking battery negative/ground in no way, shape or form is connected to the trolling motor batteries.

If that TM has the fuse in the head, check it too.

Chris-yes, I found some on my big motor. Prop is clean. Here is pic of the big motor issue, right where a small negative wire is attached.

Grout-checked the fuse in the head of the TM but it's fine. Will check cranking battery connections next. I think all grounds (for TM, graphs, power poles, battery charger) are connected to my cranking battery. Might be wrong there but I'm checking.

Get a zink anode from saltwater unit.

So the parts are being positive. Giving off ions. With the negative collecting them. With water as the electrolyte.

Corrosion would indicate. The parts are positively charged. A closed circuit when in the water.


Multimeter time. Track it down. Why are the parts positive?

Grasshopper-I am far from an electrician. I've got the basics covered but when it comes to "tracking it down" is where I'll need a little help. I've had the boat for about 3 years and this problem just started happening. (as far as I can tell) I've only replaced the starting battery during those three years and hooked all leads to that battery just how they came off. The 3 deep charge batteries are still going strong. I only fish once a month if lucky. So this is happening with not much "in water" usage. I also don't have forward facing sonar and only two graphs, two power poles and a 4 bank charger. This is a pretty basic set up.....so I think!

It's reverse electroplating. Electrolysis is commonly used to remove rust. An exchange of ions.

There's a low amp positive making contact with the negative. Using electrolyte(water).

Like...say the motor is positively charged. But the boat hull is negative. Or something mounted on the boat body is negative. Causing the Electrolysis.

I know my buddies Skeeter was doing the exact same thing, seems like it was something with the MK charger.

You might call the dealership and ask if they have seen this before, bet they have.

I electroplate at home. Electrolysis also.


The power source I use is a low amp wall power pack or a battery charger. 2amps on Electrolysis.


Battery maintainer will do but it's extra low amps.


My guess. Something is ground to something it's not supposed to be. Or its a weak ground causing the system to ground to something else. By going through the water to do it.

I'll check with dealer on MK charger issue. Meanwhile, I've heard several mentions of a wrong ground somewhere. How do you track down an improper ground? Again, being an elementary level electrician, this may be a dumb question but would a "weak" ground be as simple as the ground is not screwed down tight enough? (i.e.not a secure enough connection)

Same exact issue on my 2018 Skeeter ZX 250

To fix weak grounds.



Clean any ground connection. Remove it and look between the surfaces. Any corrosion. Use a small brass brush or 220 grit sand paper. Use some acetone or alcohol after the rough cleaning. Reconnect.


If there's any corrosion in the wires themselves. Replace them.

Thanks Grasshopper, THAT I can do!! JerseyDan, what did you do to fix it?