Kayak hull joining question

Discussion in 'Fiberglass and Composite Boat Building' started by Thin water, May 28, 2006.

  1. Thin water
    Joined: Aug 2005
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    Location: Central Florida

    Thin water Senior Member

    I am making a fiberglass kayak in a two part mold. The top and bottom mold each make a part that meet each other all the way around (No overlap). I need to join the top to the bottom. The only way I figured to do it is to leave about 2" of un wetted glass sticking out of the top mold, join the two halves and wet out the glass. This will look bad and go over the gel coat on the bottom part. I just laid up a bottom half with no gel coat so I can paint the entire bottom after sanding the overlapping glass smooth. The hole in the top of the kayak is to small to allow access to more than about three feet of the inside or I would use 3" wide glass and join it from the inside. I am using polyester resin and heavy woven glass. I want to use carbon/kevler and epoxy if I get these to come out good. I have experiance making poleing platform tops, consoles etc...
    Any suggestions are welcome.

    JIM
     
  2. ondarvr
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    Location: Monroe WA

    ondarvr Senior Member

    There are several different methods of joining the two halfs on kayaks. An easy (sort of) way, is to make the two halfs and leave them in the mold, the mold needs to have locating pins in the flange and you put them together. You then reach in through the hole that appears to be too small, with a layup on a stick (1X2) and flop it over the joint, then use a brush on a sick to smooth out the glass. Some companies use a piece of trim tape over the joint on the out side if the two halfs are different colors. If they are the same color then you can just patch it with gel coat. Another method is to use a double channeled ( H shaped) piece of trim to join the two, then glass over the inside of that (same as first method). A third way is to use an H shaped trim and glue the two halfs into it. There are other methods too, but not like the one you are describing, even with your method you would want gel coat on the hull section.
     
  3. Thin water
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    Thin water Senior Member

    Kayak joining

    Thank you very much, the mold set does have locating holes all the way around. I think that will make an excellent joint on the inside using the stick to roll out the glass and wet it out.
     
  4. Thin water
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    Thin water Senior Member

    I threw away the test layup with no gel coat and made a new top and bottom with a dark blue gel coat left over from my boat.The taped joint on the inside of the mold worked great. I patched the outside seam (It had a few gaps as I did not trim it as evenly as I should have) with a mixture of 1/4 gelcoat to match the color I used on the hulls, 3/4 resin and carbisol added until as thick as bondo. The stuff is rock hard and strong. I poured one pint of resin/carbosol mixture (but still liquid) into each end for crash protection with it standing on end then poured in 20 oz of 2 part foam. I have only one major problem left that I can't cure, I am 6'06 230 lb and can't fit into the hole in the Kayak. It would get to close to the edges of the deck if I cut the hole out big enough for me to fit. I guess I will sell it and buy a Glenn L plan for their big plywood sea kayak and try again.
     
  5. Thin water
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    Thin water Senior Member

    Picture of Kayak

    This is the completed kayak with my 230 lbs using it. It has to much rocker to track straight I am considering making a rudder for it. It slides out sideways if you get going fast.
     

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  6. ondarvr
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    ondarvr Senior Member

    I have a couple of kayaks and one of them is very similar to yours. The rudder will help keep it going straight, I used them when my sons were learning.
     
  7. wolter9
    Joined: Jun 2006
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    wolter9 Junior Member

    Thin Water: what fiberglass did you use, like E glass or S glass, 7.5oz or 10oz and how many layers did you use to make the hull and how many for the deck? If you could answer these questions for me that would be appreciated.
     
  8. Thin water
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    Thin water Senior Member

    I used a layer of 6 oz woven against the gel coat, then three layers of 24 oz. (woven) It is way to heavy. I did not take into account the decked kayak's shape adding much of their strength. I am going to make another one with one less layer of 24 oz and see how it works. It is the first boat I have made in glass. I also cut the hole out bigger with a jig saw to fit in it. I used the same lay up for the deck as the bottom. It weighs about 60 lbs and is only 13 feet long. You could walk on any part and not flex it much.
     
  9. ondarvr
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    ondarvr Senior Member

    This is an old laminate schedule from the 60s, but on similar kayaks we used
    a 6oz cloth, then 3/4 oz mat, then an 18oz roving
     
  10. wolter9
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    wolter9 Junior Member

    60 lbs does sound quite heavy. But what do i know.. i've never built a kayak before :) But if you want a lighter kayak, can't you use a core material in the hull? (and in the deck unless you mount stuff to it?) CoreCell for example?
     
  11. Thin water
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    Thin water Senior Member

    Wood is a good core, cedar strips are preferred. Ligh, strong and looks good.
     
  12. wolter9
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    wolter9 Junior Member

    i read in an article that you shouldn't layup woven roving right after the gelcoat because the weave pattern would show through. You should first layup a thin layer of mat before the woven roving. I wasn't aware of that. Are there more rules like these, because i sure am not aware of any.
     

  13. Thin water
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    Thin water Senior Member

    wolter9, you are correct, that is why I used the 6 oz before using the 24 oz, it a much finer weave, the 24 oz has about a 1/4" pattern. You could still see the heavy weave pattern in the gel if you look close enough. Many mold makers use all mat for a smooth mold.
     
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