Fleece/cotton fiberglass boat

Discussion in 'Boat Design' started by spencer321, Jun 4, 2013.

  1. Mr Efficiency
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    Mr Efficiency Senior Member

    I think whatever gets retained in the final product needs to be compatible with the marine environment, cotton will absorb water even if doped with resin, and rot. Best to stick to inert, non-biological inclusions imo. But the general idea probably has some applications. I wonder if using some kind of mesh or netting under the tightly woven fabric might help keep it fairer.
     
  2. El_Guero

    El_Guero Previous Member

  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    From an engineering stand point there's a huge difference between a SOF build and what the OP is describing, which is a load bearing, rigid skin. The two are not interchangeable, nor particularly comparable.

    I've build all sorts of enclosures and structures using the method described, though I usually employ a polyester cloth, rather than cotton. The use of cotton would be fine, with no risk of moisture penetration, assuming good wetout and epoxy resin. The fibers become embalmed, so moisture can't get to them. Cotton is one of the most common filler materials used in structural epoxy formulations.

    Simply put, you can build like this, but the results with cotton wouldn't be as desirable as other fabrics, for several reasons, most of which have been stated previously.

    The temporary frame could be more like a SOF build, so oil canning will be less a problem, though you'll still have a faceted look, at least these will flow with the water paths around the hull. The fabric could be removable after the laminate is applied or if it remains, it would be intelligent to have the fibers in this mold fabric, participate to a significant degree, with the finished structure. This said, the material of choice should have a modulus similar to the resin system used, additionally it would be wise if this fabric was light and didn't absorb more resin then necessary, to keep strength up, and weight down. This is precisely why 'glass is most commonly used.
     
  4. El_Guero

    El_Guero Previous Member

    Spencer,

    There are a number of classes offered around the country which teach skin on frame techniques. Most aircraft have moved away from skin on frame, but there are still classes taught for that venue.

    From what I have read so far, the two leading techniques are SOF using Nylon, or Polyester. Nylon when wetted and dried shrinks to form a drum like surface over the longitudinal members of the frame.

    Dacron works, but it does not tolerate abrasion as well as does Nylon.

    http://www.seawolfkayak.com/sb-workshops

    http://www.adventureout.com/survival/traditional-kayak-building/

    http://www.skinboats.org

    Wayne
     
  5. El_Guero

    El_Guero Previous Member

    When the OP poster added this "Why would you remove in [sic] from the frame?"

    I think of SOF immediately. Using poly, dacron, or Nylon instead of cotton is just because that is what the technology has identified as better to use.

    Yes, some use canvas and paint over it. But, most use Nylon or poly. Nylon because it shrinks to fit tighter.

    IMHO. YMMV.

    Wayne
     
  6. El_Guero

    El_Guero Previous Member

    Here is a video from dreamcatcher boats' school.



    It is better if you turn the music down IMHO.
     
  7. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    I assume he was going to wet the cotton with polyester, not epoxy. And if he intended to make the boat from polyester/glass, overlying an epoxy-cotton skin would de-laminate.
     
  8. spencer321
    Joined: May 2013
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    Location: melbourne fl

    spencer321 Junior Member

    Maybe if I give a 3d cad this will be simpler, but basically a rigid, structural frame, wrap it in the absorbant material of choice, wet out the material of choice with epoxy resin, once it cures you have a solid rigid skin (although not strong enough you need a few more layers of fiberglass cloth) and a solid interior frame, build your floor inside add glass to outside and you have a hull, let me draw up EXACTLY what I have in mind, maybe thatll help you all tell me yes or no
     
  9. El_Guero

    El_Guero Previous Member

    While most SOF builders use a frame to build around, this on-line course builds using only the kayak itself.

    It starts with the gunwales, and then adds the keelson. To that are added ribs and then longitudinals. And finally the skin.

    http://www.instructables.com/id/Build-a-Greenland-Kayak/

    Wayne

    A great idea I got from one of the SOF canoe builders was to cut a 3/8's deep groove into the top of the gunwale and force the skin into that with some glue. Then do the same for the skin for the deck. And then insert a strip of wood to cover that up.

    That way you do not have the stitches going down the center of the kayak.
     
  10. El_Guero

    El_Guero Previous Member

    Spencer,

    You are talking SOF. You can build canoe or Kayak easily. Larger boats are also done with this method.

    The materials of choice are usually man made. Canvas is still used, but as was mentioned, it does rot over time, even with a good coat of paint.
     
  11. El_Guero

    El_Guero Previous Member

    I think you were the person who mentioned using a cut in the gunwale to hide the stitches for a kayak .... on a different forum, with pics of a BEAUTIFUL kayak ....

    Was that you?

    Wayne
     
  12. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Why epoxy ? That only makes sense if the whole build is in epoxy, which makes it pretty expensive.
     
  13. El_Guero

    El_Guero Previous Member

    Here is the photo which got my attention several months ago:

    [​IMG]

    And another: [​IMG]

    I admit, vinyl would probably not be my choice. But, that makes a beautiful boat.
     
  14. El_Guero

    El_Guero Previous Member

    This is more like floating art

    [​IMG]
     

  15. spencer321
    Joined: May 2013
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    Location: melbourne fl

    spencer321 Junior Member

    ok I hope you can see what i drew up, its crude but i'm making my point, take a typical flat bottom hull, if framed in longitudinal members you simply lower the center member and push it forward to create a shallow V that hopefully won't beat you to death like a flat bottom...
     

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