Unusual Trolling Motor Issue

[Dan]

My fishing partner has a motorguide touring edition 82 lb. thrust. Recently he used it in a tournament and at the end of the day the shaft of the trolling motor had turned yellowish like it had been burned in a fire and it was all pitted. Also his stainless prop on his big motor was all tarnished. There is considerable rust on the seem of the motor. It appears to be leaking electricity. I have talked to the owner of our local tackle shop and he said he has a regular that this happened to as we. His recommendation was to put a ground wire on each battery and ground it to the motor or jackplate, whereever you can get a good ground. Anybody ever have this happen? We dropped it off at DNR sprots today and he put on an old trolling motor. We're headed out to prefish for the BFL tomorrow.

[TritonTR20]

Strange. If the rust is causing a leak it will fry the control board in the lower unit. They charge $75 to take a look at it. The housing and control board on mine (109Lb) cost $366 to get fixed becaused it developed a leak. If your is not digital it will most likely require an upgrade also which cast a few hundred more...hope thats not the issue.

[Dan]

What's really strange is that the stainless steel prop on the big motor looks like it's been dipped in acid. No shiny finish left.

[djkimmel]

Been quite a while since I read about this, but if things are not set up right, you can get a current between the two motors that will cause what you describe. I thought the anode on the big motor was supposed to help alleviate this?

Did he fish in a marina all day? Weak idea because it is supposed to take more time than a day.

I would DEFINITELY have a knowledgeable professional work on this issue because the cause needs to be identified and resolved.

Here's a decent summary of galvanic corrosion and electrolysis:
http://boatingsailing.suite101.com/article.cfm/corrosion_and_electrolysis_in_boat