Bottom paint on Blister repairs

[JPS27]

I pulled my e27 for some early spring work. After 22 months in the water the bottom was generally in excellent shape. I was dumbfounded actually by the good condition. However, in a few places where I made blister repairs in the past, the WM ablative bottom paint wore off down to the epoxy. According to Don Casey's book and other guidance I've found you shouldn't have to put barrier coats on the epoxy assuming the correct thickener is added. I've made numerous blister repairs, and only a few spots were problematic (having piles on barnacles on that spot).

What could have caused this? Simply not roughing up the surface first? Or maybe on some repairs the epoxy was still curing when I painted over, thus allowing for better adhesion of the bottome paint? Any advice before I start repairing a handful of new blisters and rolling paint on will be appreciated.

Interestingly, except for when I first took the boat back in 2012, the blisters are always found on the keel. Wonder why?

Jay

 

[toddster]

I had a bit of that problem this year. The first time, when everything was coated in fresh barrier coat, the ablative paint stuck very well, everywhere. Last year, I stripped off all the antifouling and repainted - not such good results. In particular, it fell right off where I had done some patching on the rudder.

There is some arcane voodoo about exactly when you can apply the antifouling paint. Like, ten seconds after your thumb no longer leaves a print in IP2000 or something, but no more than 30 minutes after that. (Probably not that, exactly, but best I can recall without researching.) Outside the magic window, some additional prep is required. I think I lightly sanded and wiped down with acetone, but that didn't seem to do the trick this time around.

 

[Loren Beach]

I have not had any bottom paint adhesion problems in either of our boats for the last 30 years, and there are epoxy surface repairs in places on both hulls.
Arcane voodoo, indeed!
:eek: