Re-Gel Coat Project

[N-Aimless]

We have been in Rio Dulce Guatemala for the last few years. While here we had the boat hull re-gel coated. It's a 1980 boat and has been painted at least three times that I know of. I did it. During Covid lock downs a number of boats had very nice looking gel coat projects done. Two colors, beige matching Awl-Grips "Moon Dust" and burgundy red matching Awl-Grips "Claret". Our gel coat project was completed In August, 2021. Recently I have discovered cracks appearing in the burgundy finish, particularly on the top curved are of the rub rail. I am in conversations with the performing marina, regarding rectifying the problem. But before proceeding with a repair or re-application I would like to understand the cause of the issue. Enclosed a couple of sample photos.

Can anyone provide an explanation for the cause of the cracks? Suggestions regarding repairing, re-applying, or removal and re-applying?

[Celestialsailor]

Hard to tell from the pictures but my guess would be that the gelcoat had been applied too thick or mixed too hot.

[Emmalina]

Need to grind them back to find out how deep they go then re-glass using epoxy. Does look like a bad mix !

[phorvati]

they cut corners on prep, and/or red gets very hot, expands in heat more than primer or whatever substrate is beneath. did they remove all prior paint, fair, prime etc. I've sprayed gelcoat over old gelcoat and never had cracks. But my gelcoat was white. I don't know what substrate besides gelcoat or fiberglass you can apply gelcoat over.

why is that last photo so blotchy and discolored?

the beauty of gelcoat is the shine can be restored at any depth beneath the surface. Interlux perfection or awlgrip have the glossy pigment migrate to the surface during curing. so awlgrip scratches you cannot restore like gelcoat. Gelcoat you can always wet sand and buff out to a mirror finish, which is not the case with 2 part paints.
but the cracking in gelcoat could be structural underneath. gelcoat does not bend and stretch as much as fiberglass can stretch so if structure beneath flexes then gelcoat on the surface cracks. hense the spidercracks on a lot of boats.

[Sailorman97]

Originally Posted by Emmalina

Need to grind them back to find out how deep they go then re-glass using epoxy. Does look like a bad mix !

Never repair a polyester boat with epoxy. The strength is not required, the post is polyester so it is fine. Once you repair with epoxy you can never use gelcoat over it.

[s/v Jedi]

The gelcoat job seems a fail to me when I see the crack where a chip of gelcoat came off: it is like they used gelcoat as a filler or fairing compound, while gelcoat must be applied very thin to prevent cracking.