Gelcoat or Epoxy?

[blacktie]

I know. Gelcoat sticks to epoxy. or not. I'd prefer to avoid having to find out by using a gelcoat paste but I'm not sure the repair is small enough. I need to repair the damage in the photo (it's about an inch wide and fairly long). can I get away with just using thickened gelcoat or do I need to fill it in first with epoxy? Any advice would be greatly appreciated.

[PBzeer]

If I recall correctly, and I'm sure someone will confirm this if it's right, you're going to need to bevel out the gouge before you fill it with anything. I would use epoxy first, myself.

[sailingfool]

Use an epoxy paste to repair any material missing from the glass substrate, use gelcoat to fill in missing gelcoat. If the damage is very deep, remove any broken material and use figerglass/epoxy to rebuild the substrate. Gelcoat should not be too thick or it will tend to crack...

[Freesail99]

I would second what Pbzeer said. I am sold on epoxy over gelcoat.

[blacktie]

PBzeer: yes, I know I need to bevel the edge to open it up. That's necessary for gelcoat, but is it as important for epoxy (which it sounds like I'm going to have to use)?

All: And since I'll be using epoxy, I guess I'll be covering it with gelcoat to color match the hull. I understand there's dispute as to how well, or whether, in fact, gelcoat sticks to epoxy. How can I make sure it adheres well to the epoxy?

I don't think I can simply fill it with colored epoxy. Or can I?

[Freesail99]

Epoxy can be colored and I like Mas epoxy as it has no blush.

[jimmyb116]

gelcoat ie polyester resin does not stick to epoxy

[PBzeer]

Yes, you should bevel it for epoxy as well as gelcoat. Ensures a better adhesion. Before putting anything over hardened epoxy, be sure to wipe it off with denatured alcohol.

You could also use Marine-Tex (bondo for boats) instead of epoxy, though I'm not sure if you can gelcoat over that. The advantage is that it is more of a paste, so it won't run or sag from the opening. I've used it on the hull of a previous boat with good results, but not sure what the consensus would be on using it.

[Goodnewsboy]

Your damage appears to be pretty superficial. I'd sand it out a little and use matching gelcoat. You have a chance of matching the hull finish that way.

[sailingdog]

Basically, if there is a color change, you've gone through the gelcoat, into the laminate underneat. I would grind/bevel the area a bit and repair with epoxy and possibly some fiberglass, depending on the damage. The photo you have posted doesn't really give any good detail of the damage.

BTW, I was recently pointed to a study on gelcoat over epoxy, and it appears to adhere relatively well, but YMMV.