Lots of Exposed Fiberglass on my hull, questions regarding gelcoat

Discussion in 'Fiberglass and Composite Boat Building' started by JackyJ243, Apr 10, 2021.

  1. JackyJ243
    Joined: Apr 2021
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    Location: Vancouver

    JackyJ243 New Member

    Hey all,

    im looking to re apply some gel coat to the back half of my 89' speedboat. The glass is in good shape, no holes, cracks or anything like that. a few chips on the front but the main issue is the back half. it looks like the previous owners beached it alot and the gel coat has worn down right to the glass.

    Ive got some gel coat and some gel coat repair kits to try and seal this up prior to me putting on a bottom coat of paint.

    i have found lots of good information on how to apply gelcoat over existing gel coat but i cant seem to find any information on what to do if the gelcoat is completely gone and im just applying gelcoat to exposed glass. I know it needs to be prepped and sanded.

    I plan on cleaning it very well and giving it an acetone rub down prior to starting.

    What Gritt paper do you recommend? is the point of this to scuff up the fiberglass (like you would if you were going over existing gel coat to get it to bite) or to sand it smooth?

    is there anything else i should know prior to starting this project?

    any information would be appreciated.
     
  2. comfisherman
    Joined: Apr 2009
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    Location: Alaska

    comfisherman Senior Member

    I'm not a pro but have done a few of my boats. I'll usually do 80 to scuff and clean it up, then acetone to clean. Usually follow this up with 2 coats of unwaxed with a thick nap followed by a third waxed. Then it gets 220 cut fair. Above the waterline I'll do 3 unwaxed and one waxed, have only cut through sanding fair when I scrimpted on gel on base coats.

    Seems like put it on thick enough to sand and buff fair, there may be a way to apply it thinner but I've not done it successfully..... just lots and lots of 220....
     
  3. JackyJ243
    Joined: Apr 2021
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    Location: Vancouver

    JackyJ243 New Member

    how important is it to go unwaxed first? the stuff i got from my local gel coat place is a white waxed gel coat.
     
  4. kapnD
    Joined: Jan 2003
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    Location: hawaii, usa

    kapnD Senior Member

    You’ll have to get a very thick coat on in one pass, no second coat can be applied over wax, unless first fully sanded.
    See if you can return the gel coat and swap for unwaxed.
    Get a small can of surfacing agent and add it to the last coat.
     
  5. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    If you are using bottom paint, there is no need to do a gelcoat repair. Simply paint with epoxy.
     
  6. JackyJ243
    Joined: Apr 2021
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    Location: Vancouver

    JackyJ243 New Member


    this was what was suggested to me originally. I then got advice from multiple other people saying to gel coat the exposed glass. This being my first time doing anything like this im not sure which direction to go lol.

    So i can just paint with epoxy over the existing remaining gel coat AND all the exposed glass? that would protect the glass? this would save me a lot of time if i can just get away with this lol

    or should I do one layer of that waxed gel coat and then paint with epoxy? skip the multiple layers of unwaxed?
     
  7. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    The only reason to repair the gelcoat is cosmetic. If you are coating with bottom paint, that is not a concern so an epoxy primer or epoxy resin coat will be enough.
     
  8. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    You may desire to smooth any rough fiberglass with epoxy fairing paste. Purely cosmetic.

    Epoxy primer and paint will provide sufficient protection
     

  9. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    I have seen this is GRP boats, and you wonder if it can wear through the gelcoat, how far has it worn into the laminate ? Obviously you don't want exposed laminate, especially if the boat is in the water on a regular basis, and certainly epoxy primer will seal it.
     
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