Gelcoat Repair - Confused

[PGHMAN]

This is correct, gel coat will not reliably adhere to epoxy but epoxy will adhere tenaciously to gel coat and polyester resins. There are other choices for applying a finish to epoxy and gel coat isn't one of them.

I've used white epoxy appliance paint for white hulls many times and pleased with the results.

My local A Auto sells the Bondo Marine short hair filler that SoccerDad mentions and it's 1/2 the price of the 3M Marine. Ever use? I need a yellow for the hull.

 

[Sportster-2001-951C-Stock]

My local A Auto sells the Bondo Marine short hair filler that SoccerDad mentions and it's 1/2 the price of the 3M Marine. Ever use? I need a yellow for the hull.

I think you'd be fine with that. The yellow could be gel coat and if that's the case you don't want an epoxy substrate.

Basically, you don't want your filler to absorb water, thus marine fillers are designed for this purpose.

I've used regular automotive bondo before and not had any problems with it but only in the case the boat doesn't sit in the water for days or weeks. Then of course I used epoxy paint to seal it as well.

Although I've used several types of fillers successfully, I haven't used gel coat yet. Most hulls are white fortunately and so this works and the white epoxy paint works great in this case.

But in your case since you need yellow then I'd have to agree with the above advice that you might be better off using gel coat. I just don't have direct experience with using gel coat so I can't really provide any detail.

 

[Sportster-2001-951C-Stock]

Have a look for gel coat blistering if you need to understand what can happen when the wrong substrates are used, there are several aspects that may affect you if you store your boat in the water for long periods.

And I use one of those cheese grater type of rasps (the type used for drywall patching) and sandpaper to level the surface, waxed paper laid into the wet filler will help to smooth it out as well, hopefully provides for less sanding.

Here's some info about blistering:
http://www.westsystem.com/ss/assets/howto-pub2/Gelcoat Blisters Diagnosis Repair and Prevention.pdf

AwlGrip makes various paints for refinishing boats, some of the shops around here use this for refinishing yachts.

Otherwise some autobody guys know what they're doing, the ones who make repairs to fiberglass corvettes and such. It's just that the materials can absorb water then blister and peel, so the marine products should outperform.