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  • chris elkins says:

    I have heard the epoxy used is critical. Also I have heard West system, the one used in the video, is one epoxy that can be used under gel coat.

    Second issue. Those of us using epoxy never put gel coat directly on top the epoxy. We generally use a high build epoxy primer, and then a finish primer and then a 2 part polyurethane.

    We dont want to have to sand the epoxy but generally would prefer to sand the high build as its a lot easier. Just wondering why you did not test the high build????



    • ~Andy says:

      Hey Chris,

      Sounds like the process you outlined is prep for painting? That’s pretty much the exact steps I take when spraying Awlgrip ๐Ÿ™‚ I put this demo together for folks who are looking to use epoxy for their repairs but still finish off with gelcoat to blend their work. Epoxy has a lot of appeal for repair work (extended work times, stronger mechanical bonding, better moisture protection, etc). Most DIY owners are typically working on boats that have a gelcoat exterior, which is what the focus of this experiment was geared towards.

  • Dominic Iadicicco says:

    Hey Andy,

    I keep hearing that a product call System Three SB-112 is an epoxy that is 100% with Polyester. They claim that you can use it as a tie Coat.

    Also what about Pettit’s Tie Coat Primer? Could that work. It claims it kills the blush. I can’t speak from experience.

    All the best.

    Happy Holidays.


  • Groundthing says:

    I have been using west system to plug holes left in my transom from previous owners accessories. I have found if you grind down the surface of the west sytem after cure well below gel coat with a dremel grinding bit and then use 3m above and below filler to act as a bonding agent between the new gel coat and epoxy resin, the gel coat seems to set up just fine. I get so frustrated at gel coat that wont set up. Im a novice at this stuff but am a pretty handy guy, your videos have helped tramendously. Dont listen to the critics about your videos, the education of these products are money saved in my pocket.

    Thanks for the info!

    • Mark says:

      Grinding the West System to below the gel coat seems like it will cause leaks in the future. Maybe not in a year or two but water instrusion kills boats

  • Alessandro says:

    Hi Andy
    Ok gelcoat over epoxy.
    Now I have a doubt.
    Use the epox to repair a polyester laminate is correct? The repair is safe?
    To Repair a laminate polyester of my boat which resin you advice? Polyester or epoxy?
    The crack is below the waterline.


    • ~Andy says:

      You’re safe to use poly above or below the waterline. If below the waterline I’ll typically do any fairing with thickened epoxy as it provides a better moisture barrier. Once the shape is right, then a coat or two of bottom paint ๐Ÿ™‚ Hope this helps!

  • Pat Chouinard says:

    I am thinking about sanding down stress cracks on a Laser hull and then laying in fiberglass cloth using the 206 epoxy based on your test followed by bottom paint.

    Logically the test results should be independent of whether epoxy is applied to gel coat or gel coat is applied to epoxy. Or do you have a different recommendation?

    • ~Andy says:

      Hi Pat! If you’re looking to prevent stress cracks from coming back, I’d sand the surface down to bare glass, then apply the new material followed by bottom paint. Its aways best to apply glass onto glass (when possible). Hope this helps! Thank you!!

  • […] is the first of a two-part video series clearly demonstrating the techniques Andy used for his challenge, following up with the results as […]

  • mat keller says:

    How about same prep, epoxy over gelcoat? I’d like to spray jelcoat in my female mold, cure 3 days, remove amine, scuff well, then build epoxy and Kevlar boat as usual.

  • mat keller says:

    How about jelcoat in a femaile mold, prep as in the video, then make a Kevlar/epoxy boat?

  • Mchael Senn says:


    I really enjoy your site and the You-tube video you provide. I have just completed a repair using the west system. I would like to use the Petitt EZ-Fair over the fiberglass repair. Once the EZ-fair is properly shaped I would like to finish off with Gel-Coat. Do I need to coat the EZ-Fair with anything to give it a good bond to the Gel-Coat?

    Can I coat the EZ-Fair with 105 Epoxy Resin let it set then finish off with Gel-Coat? Or do I need to coat with Petitt protect. Or is there another product you can suggest?


    Mike Senn

  • Powerabout says:

    I would be more interested to see a test of gelcoat over unknown epoxy and left in the weather for a few months.
    There are boat builders using epoxy layup over gelcoat in the mold and that works but repairing them is another matter.

  • Terry Kelly says:

    I am building a 16′ stitch and glue power boat designed by Bowdidge Marine Designs in Australia. The boat is epoxy and 12 oz. biaxial glass over meranti marine plywood. Mark Bowdidge has been using Gelcoat over the epoxy on his boats for years but only on the inside of the boat. They call it flow coat and add styrene to slow the cure rate. It is brushed on and then flecked with a spray gun. Check out his web site for all the details.


  • Danny Mydlack says:

    Hi Andy. Your videos are strike such a perfect tone; you really have a sense of your audience! This is a sort-of obscure question be relevant. I was reading online about the renovation of a Gougeon G-32 Catamaran. The person doing it is a professional boatbuilder and was working closely with West Systems people in consultation. Now, the renovator is a self-admitting obsessive. But he found it necessary to remove ALL the original gelcoat from the Gougeon-produced, West-System boat. It was epoxy laminate into polyester gelcoat with some kind of ‘tiecoat’ included in the layup schedule vacuum pressed into the female mold. Here’s the link:
    I was wondering what you thought. I am preparing to build a trimaran using a similar technique but his renovation has given me pause.
    Thank you again for your wonderful videos.
    Danny in Baltimore

  • pat says:

    I am using a male mold to build a bimini covering for my center cockpit sailboat. I will be using epoxy resin for layup. Usually I would shoot gelcoat over the mold prior to layup when using polyester resin. Can I still use gelcoat or should I paint instead, after popping the bimini from mold?

    I am guessing, if I use gelcoat I would need to let the gelcoat fully cure, washing away blush, prior to epoxy layup?

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