Skin on frame pontoon boat?

Discussion in 'Boat Design' started by Artifex75, Mar 18, 2011.

  1. Artifex75
    Joined: Mar 2011
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    Artifex75 Junior Member

    This may get me laughed off of the forums, but here goes...

    I'm broke. More specifically, my wife says that I'm broke. She seems to be doing fine. :mad: So, I have a very small amount of money allotted to me for boat construction. I am, however, lucky enough to have everything I need to built a skin on frame kayak. I just don't care for kayaks.

    I'm a complicated guy.

    So, would it be possible to use a skin on frame technique to build the pontoons for a pontoon fishing boat about 10-12 feet long? My worry is that the design in kayak form is successful because it can flex, but I would have to make it too rigid to support the deck as a pontoon boat. Would this lead to cracking and failure?

    Should I just give in, sell a kidney and buy the plywood I need for a more robust design?
  2. NoEyeDeer
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    NoEyeDeer Senior Member

    Can you sell the wife instead? I get the impression that she is the current main expense.

    If selling wife is not practical, I suppose you could lash two SOF yaks together with beams/whatever to make a pontoon boat/catamaran. Can't see why it couldn't be done, but presumably you'll be wanting solid decking anyway and presumably that would be plywood so............
  3. Artifex75
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    Artifex75 Junior Member

    I tried, no one wants to buy her. Can't blame them, really. She's not much of a cook.

    I had toyed around with the dual pre- built kayak idea, but For some reason people around here treat them like gold. A kayak with a hole in it the size of a bowling ball is on craigslist as a fixer upper for $200.

    I could go the plywood kayak route, but I could get into a number of sheets of plywood I'd rather not buy if the skin on frame idea could work. I just worry that I might need to put some manner of beefier frame so that it might be rigidly attached to the deck.

    Anyone ever seen SOF pontoons? I imagine that if it hasn't been done once or twice by now, it's probably because it's a bad idea, and the product of such tinkering resides on the bottom of a lake somewhere.
  4. Submarine Tom

    Submarine Tom Previous Member

    How about hip-waders instead?

  5. Squidly-Diddly
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    Squidly-Diddly Senior Member

    sounds do-able. you say you have everything you need....

    what sort of frame stringers you got?

    when I was about 13-14 I built a kayak with PVC pipe. I underestimated how much it wouold flex under water pressure even 6" down and ended up putting a layer of fiberglass and resin over the nylon skin. That fixed it.

    Start saving 1 gallon jugs with screw tops to fill the pontoons for extra safety.

    I don't see any probs with a the flex of the SOF and a platform.

    I would make the pontoons deeper than a kayak, so their bows wont tend to get 'held under' and slowly but surely swamped by little waves. Figure the platform is going to keep them from riding up on each little wave as a kayak does sort of the pivoting or 'hobby horsing'.
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Bottom loading on a small pulling boat, kayak, canoe, etc. is extremely low. This would be the first thing I'd look at if considering something like this. As a power craft, I can see only problems, particularly if the accommodations were typical of a usual pontoon boat. I would think elasticity differences between the pontoons and deck would kill any hope of more then displacement speeds.
  7. Artifex75
    Joined: Mar 2011
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    Artifex75 Junior Member

    A valid point, but my son would have to ride on my shoulders. :p And he's a little short for hip waders.
  8. Artifex75
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    Artifex75 Junior Member

    It's not actually going to be a powered craft. It'll be pedal powered, either via a prop or a fin drive like the Thistle. So, probably no chance of pushing the bow under if I make them large enough to have proper buoyancy.

    I've got a ton of pine and oak lumber that I can rip down for the frame itself, so I should be okay there.

    What material should I skin it with? I've heard that canvas covered with fiberglass resin is good, but I've also seen a plastic type cloth.

    Should I make the cross section a little more of a diamond shape than the kayak's squat oval?
  9. portacruise
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    portacruise Senior Member

    How about this type which is inflatable and can be had at huge discounts slightly used on Craigs or from bargain barns of various retailers?

    They have large 3 man and 2 man with everything worked out for frame stresses, buoyancy, etc. Sometimes when you try to save money by building from scratch, it costs you much more from all the trial and error corrections, to say nothing of your time which has to be worth something.

    Here is a version adapted to pedal power, scroll down to the bigger versions for ideas that might be adapted to your concept;

    I have built my own custom versions using 1/2" or 3/4" galvanized steel pipe for the platform and trampoline platforms to be self bailing that copy some of these designs.

    Probably the cheapest way to go for the power system is by using old bike parts, something like they did for this recumbent:

    You have to turn the output by 90 degrees for prop drive and this can be done with an enclosed flex shaft like used for drill outputs or by sitting sideways like in the sidewinder:

    Lots of designs and ideas on this last page.

    Hope this helps.

  10. Artifex75
    Joined: Mar 2011
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    Artifex75 Junior Member

    Thanks, Porta!

    The Profish pontoons are a little out of my price range, but that last link was incredibly helpful. The most important lesson is that I can't skimp on the pontoon size. The sidewinder creator weighs 100 lbs. less than I do and his boat was nearly swamped. That's the size I was planning to build my pontoons, so I've got to scale things up a bit. Ironically, I'm building it to lose weight, so perhaps my next boat can have smaller pontoons. :D

  11. thedutchtouch
    Joined: Feb 2010
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    thedutchtouch Junior Member

    take a look at the skin boat school's Zumiak it may help you with your plan
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