We pulled the boat this past weekend after it sitting in the water all season. We noticed there was light corrosion on my Bravo drive. Didn't think we could get corrosion in fresh water. The zincs are in good shape.

After inspecting the drive I noticed that one of the ground straps was cut. The boat doesn't have shore power but, would the cut grounding strap cause the corrosion?

Thanks for the help.

I only boat in freshwater and we see corrosion all the time even on new boats. Texoma does have a lot of salt though.

Iron rich freshwater can be just as bad or worse than salt water for corrosion. If you are boating only in fresh water, switch to zincs specifically for it (magnesium?). I had issues last year when I bought my boat. I'm at work and don't have the time to type out the whole story, but, yes, I would suspect the grounding could cause an issue.

Thanks for the response. I did read on Mercs web site that they recommend you use magnesium in fresh water.

I use to run the boat in the Chesapeake bay but it was dry docked. Now it sits in the Potomac River which is fresh / brackish.

Does the snapped grounding strap have anything to do with it?

My boat was a cruiser, and had shore power hooked up to it, but it was caused by a loose ground at the grounding bar. So I would suspect it could. I read everything I could on mercruiser corrosion, and bought a test probe to check it. It took getting everything in my mercathode system perfect, all grounding perfect, and magnesium annodes to get my readings where I was happy.

[I use to run the boat in the Chesapeake bay but it was dry docked. Now it sits in the Potomac River which is fresh / brackish.


Brackish water is not fresh in the corrosion world. The corrosion rate goes up big time as the salt content goes up. If the water is susceptible to tidal influences from the ocean and gets even a small amount of salt contamination that could be the cause of the corrosion.

OH, BTW the grounding straps on the drive and the transom assbly have to be connected for the anodes (zinc or Mg) and the Mercathode to work. You do have Mercathode?? The Mercathode supplies a small current in the opposite direction of the electrical current from the corrosion to reduce the corrosion potential and the damage from the corrosion. You have to have a continuous circuit to ground (the grounding straps) for it to work.

Can also depend on hard or soft water akiline or acid and whoo or what is parked next to you.

Yes, I do have Mercathode. I am going to fix the cut grounding wire and switch to Mg anodes.

running a s/s prop can cause a lot of that as well....something about the aluminum housing vs the s/s prop