It's got to be in the way they were installed, boat will be out of the water for quite a while, so I can check and se what is not right and causing this problem. I may even pul them back off so that I can sandblast and re paint and check everything from scratch.

The big indicator is that this boat didn't have a problem for 15 years until the new ones were installed, so I need to work backwards from now till then and I will figure it out.

THanks for the help. These are basically the same answers that my own research has revealed all ready.

Did you check that the ground wire inside the bilge was reinstalled, the one that screws to the steering lever and to the inner transom plate?

It doesn't really matter how it happened. It will get fixed. I appreciate all the input so I know where to start looking.

Is it possible that a bad battery bank (meaning dead) would cause the mercathodes to not function properly? This could be the problem.

About 3 months before I took it out of the water, my genset and battery bank for the starboard engine went dead and I could never get them to charge back up. The corrosion does not look like it has been there for a year. It looks like it had only been there for a few months.

Am I thinking along the right path here?

If all the batteries would have stayed HOT? Would I have not had the problem.

Not sure that there is anything wrong with the instalation. Still checking, but I think that issue has been put to bed all ready.

Figure it out eventually. Weather is getting warm here so I need to get her back in the water one way or the other.

Possibly. Mercathodes require 12v to operate. Usually a fuse at the controller. Can see if there is voltage there and not blown. Normally these are wired for full time 12V, just like a bilge pump, so their operation can not be defeated by turning off the battery switch. So may depend on which battery bank they are powered from.

B3's need all the protection they can get. Assuming this is what you have on the Sea Ray