Fiberglassing problem

Discussion in 'Fiberglass and Composite Boat Building' started by schlump, Oct 11, 2014.

  1. schlump
    Joined: Oct 2014
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    Location: Houston, TX

    schlump New Member

    I am in the process of fiberglassing a 12' custom wooden pirogue using West system epoxy. The bottom of the boat has 3- 5/16" x1-1/2" skid rails running from bow to stern. My problem is air pockets forming along the edges of the rails where the cloth bends up and over when I'm wetting it out. I experimented with a small section and its terrible. Any suggestions or advice would be most appreciated. This is my first attempt. Thank you.
     
  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    What weight cloth are you using? Fiberglass will not bend 90 degrees. The proper solution is to make a fillet to fill in the inside angle.
     
  3. schlump
    Joined: Oct 2014
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    schlump New Member

    I'm not too sure of the weight of the cloth but it's pretty heavy. I got it from West Marine and just called the sales guy who sold it to me and even he wasn't sure. I do believe your suggestion for the fillets will be the solution to my problem I feel confident. Would it be advisable to use the West System epoxy for the fillet or is there a better filler - technique?
    Thank you for the prompt reply.
     
  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Welcome to the forum.

    It sounds like you have too tight a radius at the intersection of the rub strips and bottom. This is solved with a cosmetic fillet, along the edge, where the rub meets the bottom planking. This fillet allows the cloth to lie down neatly, without puckers or bubbles. On a 2x4 rub strip, you'll want a 3/4" tall fillet, generally, so mix up some fairing compound (west System 407 or 410 works nice, as does System Three "Quick Fair") and smear a nice 3/4" tall radius along the seam, then you're good for the cloth. It's preferable to apply the cloth while the fillet is still wet or just past tacky, so the cloth bonds to it as well as the boat.
     
  5. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    As well as the previous good advice, sometimes the glass will 'creep' after you have smoothed it down. You can come down the next morning and find the glass has moved off the surface.

    In tricky situations, I have found that applying peel-ply can solve the issue. It seems to 'press' the glass down, I think a bit of atmospheric pressure is working here. You also get a better finish of course.
     
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    In the field I've not had access to a vacuum pump, so I've used a bag of water. A garden trash bag is fairly heavy plastic and big enough to cover say a small centerboard or rudder blade. Cover the work with peel ply, maybe some bubble wrap, felt or whatever to prevent the bag from leaving wrinkles in the goo, then fill it with water from the tap. Hot water will help kick it off in cooler weather. The bag will conform to edges and shapes well, plus add some pressure.
     
  7. schlump
    Joined: Oct 2014
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    schlump New Member

    Thanks to all for your replies and advice. I should have asked sooner but how can I correct those air bubbles on dry fiberglass? Last weekend I started on the stern which is a flat surface and I have some there also. I thought it was wetted out properly.
    I hope to complete this project this weekend.
    I'm new to this board and find it very interesting and informative.:)
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Typically, you grind out the offending areas and fill them in with thickened goo or more fabric or both. No, you can't simply add more goo and hope it fills in.
     
  9. mehsjohnson
    Joined: Oct 2014
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    Location: Sitka, Alaska

    mehsjohnson I hate grinding!

    I agree. Grind it out and fill it in. You want to prevent water getting into the wood. A couple coats of epoxy resin should fill in any micropores after you fix the bubbles.
     
  10. schlump
    Joined: Oct 2014
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    schlump New Member

    Fiberglassing problems

    The fillets worked very well on the skid rails. Now my next issue is with my wetting coat turning kinda milky as I'm applying it but only in some areas. I'm using a rather cheap Home Depot brush. I love doing this stuff but it can get a little frustrating at times. Again, I do appreciate any advice.
     
  11. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Using a brush isn't the best tool, though inside corners do make using one the only choice. I plastic applicator, squeegee and roller are much preferred to brushes. I using 'glass fabrics and it's milky, you're not fully wetted out, so slap on more goo and press it into the fabric. Bubbles and floating fabric will also look milky, so mash these areas down, so it's in the goo. Most of this stuff is simply learning by doing, especially after you have to grind out something (like a bubble) to make it right again.

    I may have previously mentioned this, but download the free "Epoxy Book" from System Three:

    http://www.systemthree.com/reslibrar...Epoxy_Book.pdf

    . . . and the free "User's Guide's" from West System:

    http://www.westsystem.com/ss/use-guides/

    . . . also the "Gougeon Brothers Boat Construction" book:

    http://www.westsystem.com/ss/assets/...k 061205.pdf

    Most every question you have can be found in one of these texts and you'll be well armed to tackle your current and next projects.
     

  12. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    The problem is air entrapment, not the brush.

    You are basically working the goo too much. Its not a problem structurally, only aesthetically.

    All the wet out guides say to squeegee it once and if its wet, leave it. Dont re-apply the drip-off from thje squeegee - thats the milky air entrapped stuff.
    https://www.youtube.com/watch?v=oGS2Gs78Zl0&list=PL54989AD4A76D7849&index=21

    A great tip is to use a heat gun on low temp while you are wetting out the cloth. You will find you get a complete wet out quicker that way, and you wont have to keep 'mooshing' the brush..
     
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