Boat bottom paint prep and blisters questions?

[Harp]

I have kept my boat in the water all season for the last four or five years cleaning at the end of the year is a chore and lots of preformance robbing marine growth 44 MPH in 35 by season end. This year I noiticed I have blistering in the gel coat [big blisters]so as a fall winter spring project I am looking to DA the whole bottom, fill and paint any hot tips? better paints or major mistakes to look out for? I am currently looking at Hydrocoat by Pettit in black looks like a fit for winter season pullout, lasting the longest maybe two seasons? and water clean up. I read about using an exopy type product over the blistered areas but do I prime the bottom it has never had bottom paint it is fiberglass if you didn't get that? or do I DA with 80 disk it down fill it blisters and paint a couple coats??

[Steve Bakken]

Painting over gelcoat can be done if prepared correctly, but one thing you'll find is that the paint is much less durable than gelcoat and soon you'll notice the originall gelcoat color peeking through chips and scratches. When we repair blisters in gelcoat we find that they most often come from "voids" or air pockets in the fiberglass where resin did not get soaked into the glass fibers. This will need to be ground out and filled. Then you'll want to paint the entire area to be painted with a good epoxy sealer. This will fill the pinholes in the filler and also isolate any other imperfections in the gelcoat. Once this is cured then you can go ahead with your topcoat, following the manufacturers instructions. IMO, before you go through all this work, you may want to evaluate how bad the blisters are and how many of them you have. 95% of the time when we do a repair of this nature, we have found that you will come out ahead both in time and money, by spot repairing the bad spots with gelcoat. This also will leave you with a much more durable hull than one that has been painted. Which ever route you decide to go, good luck and I'll try to help with any other questions you may have.