how many layers of cloth and resin for a jon boat hull...

Discussion in 'Materials' started by cracker39, Feb 11, 2015.

  1. cracker39
    Joined: Feb 2015
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    cracker39 Junior Member

    I'm considering building a stick-steer, jon-type fishing boat to use with an outboard motor up to 20 hp. I've built one before, using luan plywood with a single layer of glass cloth on the exterior of the hull and just resin on the interior and used a 7.5 hp outboard on it. It lasted about 5 years before wet rot began in the wood.

    This new boat will have laminated glass bottom and sides, with glass tape on the seams, attached to a pressure treated wood frame. The stern will be PT plywood covered with glass cloth and resin inside and out. The interior will be open with two pedestal seats. Rod compartments on either side should add to the structural rigidity of the frame. For further clarification, I can provide drawings to illustrate.

    My question is how many layers of 10 oz or 6 oz fiberglass cloth will be strong enough for the bottom and sides, yet still flexible enough to bend on the curve towards the bow.
     
  2. gonzo
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    gonzo Senior Member

    Why do you have to bend fiberglass if you are laminating a bottom or sides? They cloth will take any shape the mold has.
     
  3. cracker39
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    cracker39 Junior Member

    Actually, I hadn't thought about bending the layout plywood sheets I would be using as a form to do the laminating. That is what I should do. That takes care of the bending question. Now, for how many layers I'll need to laminate for a sturdy hull. I laminated some cloth once to make kayak paddle blades. I don't remember what the weight was, but I laid up three layers and it was very rigid.
     
  4. Trent hink
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    Trent hink Junior Member

    Are you planning to use epoxy resin?
     
  5. cracker39
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    cracker39 Junior Member

    I've used polyester resin on my fiberglass work before. I'd like to use vinylester or epoxy resin, but the cost is much higher. A couple of coats of epoxy marine paint over the hull made with polyester resin should keep water from getting into the glass and resin.
     
  6. ondarvr
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    ondarvr Senior Member

    For better answers we may need to know a few more things

    Why do want to build this boat?
    You love projects and want to build one with your own hands?
    You can't buy the type or design you want and building it yourself is the only way to get one?
    You feel it will cost less to build it yourself?

    All can be good reasons.

    While you could build it with these materials, it's an odd combination that may not work well together.
     
  7. cracker39
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    cracker39 Junior Member

    For better answers we may need to know a few more things

    Why do want to build this boat?
    You love projects and want to build one with your own hands?


    I do love to design and build things, working with wood, and the personal satisfaction of building my own boat is important to me and it will be exactly what I want for fishing. The fact that I can say "I built it" also means a lot to me.

    You can't buy the type or design you want and building it yourself is the only way to get one?

    I could buy an aluminum boat of this type, but…

    You feel it will cost less to build it yourself?

    …The cost of building my boat of wood and fiberglass will be less than buying an aluminum boat of the same type. And, repeating myself, the boat that I'll build will be customized to my exact needs.
     
    Last edited: Feb 13, 2015
  8. ondarvr
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    ondarvr Senior Member

    Why do you you want to build it with those materials?
     
  9. Canracer
    Joined: Aug 2009
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    Canracer Senior Member

    I think your considering to build the same design that you built previously. The second time around you want a stronger hull because you want a bigger engine?

    I know that epoxy is more expensive, but it's sooooo much better than polyester (at everything.)

    I'm imagining a 15 to 17 foot boat.
     
  10. cracker39
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    cracker39 Junior Member

    This boat will be the same general shape as the one I built before, except 2' longer, side rod storage, and stick steering. Instead of a flat bottom, I'd make it a shallow V bottom. At 14' long, I'd probably look for a used 15 hp outboard. I fish mostly in lakes not more than 1-2 miles across, so I don't need a lot of speed. I may abandon my plans for an all glass hull for a marine plywood hull covered with glass cloth and epoxy resin inside and out. That may increase the weight a little, but save the cost of glass cloth and resin. I'm using a 16' bass boat now. It wouldn't make sense for me to sell that boat and build another the same size. I want a smaller, lighter boat that my wife's
    Tucson can tow when we go camping and I tow the travel trailer.
     

  11. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    There are many low cost, or no cost plans around for a boat like this, they may include all of the information needed to do the entire build. There isn't much of a cost saving when skimping on the quality of materials.
     
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