I have an '04 18 Donzi Classic with a 350 Mag / Bravo 1 and about 55 hours on it. Used in fresh water only, I run synthetic drive lube and a Simrek drive shower. So, honestly, I run it about 3k - give or take - most of the time with the requisite blast now and then. When I pulled it out last weekend, I noticed that the top cap - where it meets the upper - is chalking, to the point of raising the paint off the cap. It is just at that seam, and the rest of the drive is mint. I change all the anodes each season so the ones on it are new a/o July. It has the Mercathode system and I keep it at my dock, a private residence, not a marina.

What gives!? It is the water I'm in, or is it another problem that I am unaware of? I don't remember this problem (this soon) on previous boats I have had, so I am a bit perplexed... any thoughts?

Thanks,
Mark.

Know ofa few boats less than a yr old that have drives look like they are 10 yrs old. It's not a factor of having a drive shower or not. Just boats that live in the water. Seems like once the corrosion gets in under the paint, it goes like a kid in a candy store. The joints are usually the 1st place it starts.

Doesnt sound like you are talking about "chalking" ...caused by heat....
Water is getting under your paint were it was chipped during Assembly.
It will continue lifting the paint

Post a picture...lets see this

Try some lime away but keep it off the stainless.

Magnesium anodes are a must in fresh water, they make a huge difference. I replaced my stock zinc anodes with mag. on my new Formula and they need replacing after 5 months in FW. They are sacrificing themselves instead of my cases, (other than some at the top cap seam). You have to understand whats going on. The massive latham stainless wingplates on my tops, and all the other stainless in proximity to those alum cases make for a pretty strong electrolitic effect. Galvanic corrosion cannot be avoided on a boat that stays in the water, you can only hope to contain it to a reasonable degree. Magnesium anodes in FW!!!!

Thanks, I feel a bit better now... The boat is in my garage up at the lake, I hope to go up this weekend and will take a picture or two if I do.

I do have the Mag. anodes on the drive, I have always made sure they were Mag,. vs. zinc in the (fresh water) lake. And it is just at the top seam, where the cap meets the upper housing, and it is only on the cap. Guess if I wanted to be really particular, I could just change the cap out for a new one?