kevlar canoe build

Discussion in 'Boat Design' started by zachjowi, Feb 13, 2011.

  1. zachjowi
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    zachjowi Junior Member

    I've got my materials to start building my mold and am looking to buy the materials for the boat. I'm wondering what is strong enough for the hull. I can't find kevlar that is 9 oz so can I just use 5oz and then add 6oz S-glass like in my picture?

    The red layers are the S-glass
    The black layer is 5oz Kevlar Style 285 is a 17x17, 1140 denier, 5 oz, 4-harness satin [crowfoot] weave, thickness ~10 mils

    ******Note: Because Raka only sells the 6oz S-glass in 27" width I would probably have to add a layer below the top ceter piece and under th side two, resulting in 4 pieces of S-glass

    You can see a picture here
     

    Attached Files:

  2. gonzo
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    gonzo Senior Member

    I think the best answer will come from the designer. It is not possible to even guess since you are not providing enough information about the hull. The lamination drawing shows that the bottom is thicker. Why are you mixing kevlar with glass?
     
  3. zachjowi
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    zachjowi Junior Member

    The S-glass is to give it added strength. I'm trying tomake the boat from the book "Building Your Kevlar Canoe" I've never designed a boat so I was just looking for sme gernerl advice bout weather or not his will crack, etc. It's about 18' long.

    http://www.myrabo.com/k-canoe/kevlar2003.htm
     
  4. bntii
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    bntii Senior Member

    I own one of the beautiful VCP kayaks which is laid up with a carbon/kevlar skin.
    I can't tell you much about the layup schedule other than it is made very light and stiff by using a combo fabric like this one:

    [​IMG]
     
  5. gonzo
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    gonzo Senior Member

    Why are you adding strength, don't you trust the designer? It doesn't make much sense to add fiberglass to a kevlar laminate unless is to build a core. You are using it as a skin.
     
  6. zachjowi
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    zachjowi Junior Member

    The book' design calls for 8.9oz Kevlar, which I can't find. I can only find 5oz. The book also calls for 5.6oz S-glass 30" wide to go on the bottom like i have drawn, but I can only find 27" at Raka so that is why I am asking if going with these alternate materials wil be enough.

    Thanks
     
  7. gonzo
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    gonzo Senior Member

    Is the glass on the inside? The drawing shows a double layer of red on the bottom and single on the sides. What is the black? It is difficult to answer without knowing which is which.
     
  8. zachjowi
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    zachjowi Junior Member

    There will be a single layer of 60" kevlar on the inside of the boat, ontop of that will be two pieces of 27" S-glass side by side. Potentially I could sandwich those two pieces with 2 more 27" S-glass pieces. If that makes sense. The reason for overlapping is that the boat is 56" at the ceneter and there would be a gap between the two pieces of fabric. Hope this helps.

    Red = kevlar
    Black = S-glass
     
  9. duluthboats
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    duluthboats Senior Dreamer

    It is common to sandwich Kevlar between glass in a layup so you don’t sand into the Kevlar during fairing. I would overlap the seam at the center or use tape and leave off the 2nd layer and put it on the inside. If you have to do any fairing on the Kevlar you are in for a real treat.
     
  10. gonzo
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    gonzo Senior Member

    Is the kevlar on the inside or the glass?
     
  11. zachjowi
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    zachjowi Junior Member

    Kevlar is the inside layer
     
  12. gonzo
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    gonzo Senior Member

    The kevlar with superior tensile and compressive values should be used in the skins. It is an expensive material for a core.
     
  13. DCockey
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    DCockey Senior Member

    Gonzo had the same reaction I did. An alternative would be to use a less expensive and potentially lighter core material than Kevlar. But then it wouldn't be a "Kevlar" canoe.
     
  14. thedutchtouch
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    thedutchtouch Junior Member

    no, the kevlar should go on the inside. The reason is that the fiberglass is used as wear protection for the kevlar. fiberglass can be sanded smooth, kevlar gets fuzzy. a fiberglass outer layer would allow the smooth external surface to be maintained.
     

  15. gonzo
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    gonzo Senior Member

    A high quality kevlar or carbon laminate is very smooth. If you need to sand, then the mold is bad. It is a workmanship and technique problem.
     
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