Gel coat over Epoxy

[Bolo]

So over the past few years my main concern on my E32-3 has been to get all the running rigging working properly which included moving winches and installing new and additional rope clutches so that all of the sail controls were in the cockpit. That's done and after about a year now I'm confident that things are in the right place but what's left are the, "ghost hole's", as I call them of the original winches and old rope clutches. It's time to make them go away but I've read a few times that gel coat cannot be applied to epoxy which is what I use to fill in the old holes. So is this true? Do I need to do something special before gel coating?

I've attached two photos of some of the areas on my cabin top showing the old ghost holes which I guess I'll be addressing as an "area" rather than filling in and gel coating each hole individually. Sure, I can can any number of gel coat pros where in the Annapolis area but why deprive me of all the fun and the chance to learn something new that I've never done before? Any suggestions or tips?

 

[bgary]

I've read a few times that gel coat cannot be applied to epoxy which is what I use to fill in the old holes. So is this true? Do I need to do something special before gel coating?

Short answer, yes, you can apply gelcoat over epoxy. For pretty much any surface you want the repair to be completely cured, and then given a little "tooth". The additional step for epoxy is to scrub off the "amine blush", a residue that appears on the surface of cured epoxy. Can easily scrub it off with water and a scotch-pad.

Lots of info out on the interwebz if you search for "gelcoat over epoxy". Here are a couple:

Applying Polyester Gelcoat over Epoxy

Can you apply gelcoat over epoxy? Andy conducted experiments debunking the myth that you can't; WEST SYSTEM epoxy can be applied successfully over gelcoat.

www.epoxyworks.com

Can Gelcoat And Epoxy Bond? | Boatworks Today

Here is the first of 2 video's where I look to see if there's any truth to the belief that polyester based materials (such as gelcoat) won't bond to epoxy. It's been long believed that if you were…

www.boatworkstoday.com

....and the West System manual (downloadable as a PDF) has good info too.

Bruce

 

[bgary]

Adding a link to the West System manual. Page 101 covers surface prep for gelcoat over epoxy

https://www.westsystem.com/app/uploads/2022/10/Fiberglass-Manual-2015.pdf

 

[Christian Williams]

The holes will always be visible, though, unless a miracle of matching occurs.

For individual holes, I put in a ghost bolt. For a pattern like yours, I might make a teak plate to screw over the hole area, providing a mystery mount of nothing, but neatening for the eye.

Or you can square off the zone with tape, so that the new gel coat makes a square or a circle, which will argue to the eye a purpose that the observer merely happens to not know, and leaves him to steep in his own ignorance and your deck to have fooled him good.

I made a placard out of a hole repair that was otherwise going to look like a bug, not a feature.

......

 

[bgary]

The holes will always be visible, though, unless

True. But for a small but well-delineated area like the aft corners of the coach-roof, it's simple enough to fill, fair and resurface the whole shebang.

I hired a guy to do the gelcoat (knowing how badly colorblind I am, and that I'd never be able to match the color) and 6 years later it still looks great.