First time builder has questions about 8 foot plywood boat

Discussion in 'Boatbuilding' started by 44minimum, Nov 26, 2011.

  1. 44minimum
    Joined: Nov 2011
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    Location: On the Oklahoma tundra

    44minimum Junior Member

    Hi everyone. I'm going to try to get my nephew and niece involved in a little project and I thought a small boat would be a good one. This is the first time I've ever done anything like this so I'm going to keep it small and simple. I'd like to make an 8 foot john boat, utilizing one sheet of 3/8 for the bottom, probably 38 or 40 inches wide. I'll be using one by two's for the framework and I thought that I would put down gorilla glue and then use screws every three or 4 inches to hold the plywood and the one by two together. I've watched lots of videos and it doesn't seem hard but I have questions about finishing the outside of the boat. I was thinking about using fiberglass cloth on all of the outside seams and then maybe just coating the rest of the bottom and the sides with a couple layers of epoxy. I'm not going for looks here, I want it to be functional and leak free. I'm hoping to end up with something that looks kinda like this http://www.youtube.com/watch?v=diGR0PiciNs&feature=related

    So I guess my questions are

    1 could I just use fiberglass cloth on the seams with fiberglass resin, and then coat the rest of the bottom and sides with plain fiberglass resin? I have used this a little bit in the past making micarta for knife handles. Something like this http://www.walmart.com/ip/Bondo-Fiberglass-Resin-1-qt/17056866#Specifications

    2 what kind of epoxy would be good to use? I looked around at an online marine catalog and found this stuff http://www.jamestowndistributors.co...milyName=System Three T88 Structural Adhesive

    And I have read about something called gluvit.

    3 any idea at all how much epoxy or whatever it is that I use that I'm going to need? A quart? Gallon?

    I'm regarding this as a learning experience, so the less money it costs, the better. It should be fun and if it works out well, then a bigger one is the next step.

    Is this going to work, or do I need a completely rethink my plans? Thanks for any input you're willing to give
     
  2. troy2000
    Joined: Nov 2009
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    Location: California

    troy2000 Senior Member

    For what you're doing, I don't think you need bother with the epoxy unless you plan to make a habit of challenging rocks mano a mano.

    Slap two or three coats of paint on the boat, and drop it in the water. Whenever you have it back home, turn it upside down on a couple of sawhorses and touch it up as necessary.
     
  3. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    Troy's right. Epoxy is what to use if you are building a boat using high tech materials to achieve high strength and light weight. Then it has to be epoxy coated anyway. Epoxy is also used to coat surfaces that need a barrier to water ingress such as polyester resin/glass hulls.
    When it comes to simple low tech construction, where the boat is probably going to be dry-sailed and easily maintained, where the overall cost of the materials is low, epoxy coating the hull isn't as practical as seasonal inspection and a touch-up or two. Your boat will last a generation without all that fuss.
     
  4. 44minimum
    Joined: Nov 2011
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    Location: On the Oklahoma tundra

    44minimum Junior Member

    So I am attempting to make it harder than it needs to be, huh? OK, sounds good. Do I still need to fiberglass the outside seams? And if so, I can just use fiberglass resin and fiberglass cloth, right? It might be overkill, but I would rather build it a little heavier duty than necessary once rather then go back and try to chase down leaks two or three different times. I would like for it to float the first time I put it in the pond.

    Thanks for the information
     
  5. troy2000
    Joined: Nov 2009
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    Location: California

    troy2000 Senior Member

    My son and I built a flat bottomed canoe together, before he went into the Army in October, 2010. It has pine sides and a plywood bottom. We used a caulking fun to lay a bead of PL Premium polyurethane adhesive on the pine, spread it out, then nailed the plywood on with small eg nails.

    The canoe bakes in the desert sun day in and day out when not in use, and I've had it in the water for up to three days at a time. It hasn't leaked a drop so far.

    I did a build thread at the time. Your boat will be a different project, but there may be some useful tips in there for you anyway...

    http://www.boatdesign.net/forums/wo...ation/building-flat-bottomed-canoe-33266.html
     
  6. 44minimum
    Joined: Nov 2011
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    Location: On the Oklahoma tundra

    44minimum Junior Member

    I looked at your canoe build and it looked pretty nice. Looks like you got plenty of equipment and the know how to make use of it. I don't have the patience or that kind of skill so I'm going to be happy if it just floats. And I guess instead of gorilla glue I will be using that PL premium. Sounds like good stuff. I'm going to use screws. Are you not worried about nails pulling out?
     
  7. Wolfgang123
    Joined: Apr 2009
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    Location: Atlanta

    Wolfgang123 Junior Member

    So do you guys really think the epoxy is overkill? I am in the same boat (haha pun) as 44minimum and trying to figure out the epoxy procedures now that my boat construction is finished...sorry to thread jack but I feel like its all on the same topic.
     

  8. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    If you seal it in Epoxy it will last longer or let use lighter wood, but will add a lot of cost.
    Or just use epoxy in joints help glue it together. Use marine plywood and if you treat it right it should last several years.
     
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