fiberglass repairs

Is the West System resin a vinylester product? And can I use it to buildup my hull bottoms from some beach rash?

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Bill 404 21SE

WEST is an acronym for Wood Epoxy Saturation Technique.

It's epoxy, not vinylester.

But that doesn't mean you can't use it for your hull bottoms. The advantages of epoxy are superior chemical adhesion and toughness. The downsides are that it breaks down with prolonged exposure to UV light and will turn amber if not protected from the sun (pigment or paint).

Well, the West System did not adhere to my hull and I peeled it right off

....so what product is suggested to work well with my gelcoat. I am trying to build up a small area maybe 5" X 12" that needs material prior to having my boat re-gelcoated by my local dealer.

I would like to do all the prep work I can do before taking my boat in for new gelcoat. The local dealer, well their good people and price quote was very reasonable. :

Thanks for your input!

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Bill 404 21SE

That may have been due to some residual wax on the surface or a resin/hardener mix that was off. WEST is fairly sensitive to the 5:1 ratio - it will have a rubbery cure if the mix is off. Epoxy also takes a long time to come to a final cure (week or longer).


Definitely polyester - it's what the boat's made of - and it's compatible with gelcoat (which is also polyester). Gelcoat over epoxy can be tricky. When epoxy cures, it develops an amine blush (especially in humid weather) on the surface that's like a wax. It has to be thoroughly cleaned with solvent and the surface profiled (sanded) before going over with gel. Even then, it might not work and all you've done is create a mess.

Since you're not doing anything structural, vinylester is just a waste of money.

Most likely the result of poor surface prep and would have occurred regardless of they type of resin matrix used. You need to aggressively sand the surface and wipe with acetone to remove all contaminants and give the resin a clean surface to adhere to. After that, don't touch the surface with your bare hands.

Personally, I would not use anything other than polyester resin for a bottom job.

sm