Another hull repair question...

Thread starter #1
In my continuing saga in the repair of my super porpoise, I wanted to get a couple things clear before moving on to my next step...

I have sanded out all of the biffs/scratches on my hull, repaired some pitting with a marine epoxy, and fixed one more significant hole with a mix of fiberglass, bondo, and epoxy. During these repairs, I had to take a significant part of the hull down to the fiberglass (although the fibers are still quite sealed).

Do you recommend just painting the bottom, gelcoating the bottom, painting then gelcoating, etc?

This is a recreational boat and I'll be dry-sailing. I feel comfortable working with most paints, and have painted larger boats, but have never worked with gelcoat.
 
#2
Gel coat over paint is out. It won't hold. Gel coat itself is a pain to work with and the reason it's on the outside of most all fiberglass boats is they can spray it directly onto the mold for a nice smooth surface then glass over it.
Paint is really the best option. It will seal the surface as good as gel coat and will be a lot easier to get a decent finish by prepping the surface before paint than trying to smooth out gel coat.
 
#3
- fixed one more significant hole with a mix of fiberglass, bondo, and epoxy.

Hope that was fiberglass cloth fibers saturated with laminating epoxy not a mix of polyester resin with epoxy resin at the same time. The two resins don’t mix. One resin type can be laid over the other. Better to put epoxy over polyester. Epoxy sticks better and going the other way epoxy needs to have any amine blush cleaned away first or it will peel off. When you say Bondo I hope you mean Bondo brand polyester resin not bondo auto body filler. Body putty won’t hold up on a boat. Check out David Aiken’s book, Fiberglass Repair: Polyester or Epoxy


Do you recommend just painting the bottom, gelcoating the bottom, painting then gelcoating, etc?

Gelcoat is polyester resin same as the fiberglass is built up with. It is cosmetic because of the addition of pigment, but it’s part of the overall hull makeup. It will not go over paint. Where you removed the gelcoat you’ve thinned your hull some – not much, but way more than paint makes up for. Fair your repair area back to its original thickness with new gelcoat or either polyester resin or epoxy resin top coated with boat paint.
 
Thread starter #4
Dan, don't worry, everything was patched and filled correctly with the right materials. I may be new to small boats, but have been sailing cruisers between 22 and 40 feet on a regular basis for a lifetime and know the importance of using correct materials! This is the first case, however, where I've had to deal with a small craft that really had to be brought down to the bare hull in order to be adequately repaired. This boat was purchased for $130, after having sat unused for at least 3 years, but I would estimate more like 7-10 years of disuse!
 
#5
Thanks for the clarification. You did state you were uncertain about the correct materials so there was concern the underlayment was appropriate before you invest in a finish coat. Taking into account your disclosure this is a $130 fun boat, paint with perhaps a fairing primer is probably all that’s justified.
 
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