Motorguide stainless steel shaft corroding?

[wasabi]

My 6 month old Motorguide Bulldog shaft appears to be corroding, although it is supposed to stainless steel. It looks more like aluminum that has come in contact with a caustic subsrtance. I'm not sure how to explain what I am seeing and hope the pictures better explain. It also looks like how some metals discolor when they have been heated up - although I am not aware of any issues. The motor worked fine yesterday. Always in fresh water, never salt.





Has anybody seen a stainless shaft do this? I thought maybe it could be water getting up under some kind of clear protective coating but a closer inpsection doesn't look like this is the case. I don't recall any of my other boats doing it. I would call Motorguide but their customer support sucks.

[CatFan]

Electrolysis is a possibility. Any corrosion or white deposits on the outboard lower unit (or the hull if it's metal)?

It is a result of current flowing between parts of the boat through the water. The fix is to connect a fused wire from the negative of the outboard battery to the negative of the TM battery.

[wasabi]

It is a plastic hull boat

[CatFan]

It is a plastic hull boat

It's most common to flow between the lower unit of the outboard and the TM. If the outboard isn't electric start, then all bets are off.

[wasabi]

There is no outboard, just this trolling motor.

[J White]

WAG here, but you ain't fishin around no docks with power on them are you?

[CatFan]

WAG here, but you ain't fishin around no docks with power on them are you?

That's the next place I was going, so if it's a WAG, it's not too WA!

[wasabi]

nope, no docks and no electricity in the pond. I do use it in other ponds/lakes but I can't see any of them having an issue with this such that it would cause this much corrosion.