Fiberglass Repair 2007, Sunscape 21 LSV

[BattRonald]

Any suggestions on how to fix this? Looks like only one side is an issue. The boat is in the water for 5 months a a year in Michigan. I take it out and clean it once a month but I want to fix this and then try applying bottom paint in over the entire back area.

Also, I’m seeing some stress cracks. Are these typical or is it because I’m adding ballast bags?? 500lbs each side. There are no hard tanks. Boat has 300 hours and overall in awesome condition. 

[formulaben]

Not sure I see the cracks, but that much weight shouldn't be an issue.  As for the hardware it looks to me like galvanic corrosion.  Are you docked next to someone with shore power?  Anyway, I'd powder coat those brackets before you put them back on and add a sacrificial anode somewhere. 

[justgary]

I can't tell specifically what you are asking, but I see corrosion that looks very typical for parts left long-term in or near water.  You have aluminum brackets held on with stainless bolts, and you will get galvanic action any time they are wet enough.  Bottom painting the entire wet surface of the hull would help prevent further issues, including gelcoat blistering (which you didn't report).

I'm not a fan of powdercoating aluminum because it doesn't address the corrosion that occurs underneath on the aluminum itself.  It's probably better to clean the aluminum parts up and take them to a machine shop and ask them to chem-film (Alodyne, chromate conversion, etc.) them for you.  After that you can prime and paint them or even powdercoat if you must.

By the way, those parts should have been sealed with 5200 sealant and thus been *very* difficult to remove.  If it wasn't hard to remove, I'm curious what kind of sealant it was.

[MalibuNation]

Where in Michigan?  These folks out of White Pigeon do a great job:

https://bontragerfiberglass.com