What's the Strongest Filler to Fair Decks?

Discussion in 'Fiberglass and Composite Boat Building' started by robali, Sep 29, 2010.

  1. robali
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    robali Junior Member

    I am buildng a wood and epoxy boat and am ready to fair the decks, what is the best mixture of products to use. I have aerosil, Talc, QCell, milled fibers etc. What is the BEST combo for a stong, light, hard wearing deck?
     
  2. PAR
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    PAR Yacht Designer/Builder

    Will this filler be used over wood and under paint? Will it be used over wood sheathed in cloth and under paint?
     
  3. robali
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    robali Junior Member

    It will be used over 300gsm DB and epoxy, already laid and dry. I need to mix my own material. Thx
     
  4. robali
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    robali Junior Member

    sorry, over wood, no paint. Paint with 2pak later
     
  5. PAR
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    PAR Yacht Designer/Builder

    Of the materials you have on hand Q-cells are your best bet for lightness and milled fibers will be the best wearing. The problem is it's easy to have a light filler that doesn't wear well or a heavy filler that does wear well, but not both a light and good wearing filler.

    Since you're looking to fair smooth, use Q-cells and a touch of talc to make a smooth mixture, that's easy to sand and fair up nice. Once you're satisfied with how smooth and fair you've gotten things, you can overcoat with a tougher mixture of Aerosil (silica) and milled fibers. You'll want to put this down as neatly and as smoothly as you can, because it's a real ***** to sand this combination.

    Personally I'd use Xynole or Dynel as the substrate, after you get the surface faired. This stuff is tough and since it's a fabric, it's a better material for abrasion resistance. It requires a good bit of resin to wet it out, but it wears great.
     
  6. robali
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    robali Junior Member

    Thanks for the good info! What would you say the top builders are using when building one-offs for light hard wearing deck filler/bog? How about to fair the hulls? Curious as I have a small boat building company and want to do these things as good as we can.
     
  7. PAR
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    PAR Yacht Designer/Builder

    Again, the idea of a light, yet hard wearing filler isn't practical. You get one or the other. As a rule, fairing compounds are light and not designed for real abrasion protection.

    For example, a hull would be first faired (light weight, easily sanded mixture) until satisfied with smoothness. Then a sheathing applied over the faired surface. The choice of sheathing subject to the amount of abrasion protection you desire. Xynole being very good and paint the least you can apply. If you sheath over the faired substrate, you'll have to fair again (what's new), but it'll be a harder, more abrasion resistant surface. In other words, using fairing compound to improve abrasion resistance is not the best way to do things.
     
  8. gonzo
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    gonzo Senior Member

    I usually mix some of the light filler with silica. Half and half seems to work well
     
  9. mydauphin
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    mydauphin Senior Member

    I have also used aluminum oxide before. This i heard gives it strength. Any thoughts...
     
  10. PAR
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    PAR Yacht Designer/Builder

    Aluminum oxide helps improve epoxy fire resistance and slightly hardens it (not much strength either). Half and half silica and balloons or Q-cells will make a difficult to sand mixture that's moderately hard. The problem isn't the filler, but the application. Generally, abrasion resistance is achieved through sheathings, not fillers. If I wanted a rock hard surface filler, I'd use a notched trowel and apply a hard surface filler. Then fair this, before filling the notches with more of the same filler. Naturally, this will offer a hard surface, but I'd be afraid it would just chip out from impacts.
     
  11. GG
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    GG offshore artie

  12. wardd
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    wardd Senior Member

  13. PAR
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    PAR Yacht Designer/Builder

    Wardd, these pre-mixed fairing compounds are convenient, but that's about it. You pay a lot more for the convenience of having a premixed product, then if you buy the separate materials and mix them yourself. I can buy many gallons of raw materials for the price of a gallon of these types of products. Then again, it is convenient to just open a can and go for it.
     
  14. wardd
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    wardd Senior Member

    but do every boat builder use them?

    it just looked like a run by ad to me
     

  15. GG
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    GG offshore artie

    When i worked at Thompson Boat Co over 39 years a go they were using there products back then , and over the years they have added more & better products to there line . I have used Adtech products (fillers) while employed at Thompson boats , S2 Yachts (TIARA) ,Power Quest , and Douglas marine / Skater , along with a host of other Co's that are using there product's today and when i was at Skater when we were building Fountains , Platinum, & Cig's there product was used on all custom hulls and decks .
     
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