Split Canoe

Discussion in 'Boat Design' started by gonzo, Jul 8, 2010.

  1. gonzo
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    gonzo Senior Member

  2. cor
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    cor Senior Member

    It is nice to find more people interested in long skinny power boats (freighter canoes).

    Gonzo, anymore info or pictures of the two piece 30'?

    I have been thinking about a 24' boat built in three sections to make it easy to transport. Each piece would be light enough to move around without breaking your back, and if the pieces nested you could fit it all in the back of a truck (or maybe on the roof of a car).

    I think this would be a great way to make river trips all over the country (Mississippi, Ohio, Yukon, etc), take the boat downstream and rent a car at the end of the trip to get home. (of coarse you'd have to rent a plane to get back from the end of the Yukon, but 8' pieces would fit in a plane better than 24')

    C.O.
     
  3. ancient kayaker
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    ancient kayaker aka Terry Haines

    I too have thought of a sectional boat from time to time. I don't live at the waterside, so having the sections nest would be nice as they could all fit in the back of my van, and save the hassle of car-topping. It's not so much lifting the boat(s) on or off the roof as they are light, it's setting up the roof rack carrier and tying down that wastes the time.

    What are your ideas for the joints between sections? Most of the sectional boats I have seen attempt to have waterproof joints, which I mistrust. While I can make the joint waterproof, what if the boat gets slightly damaged - can I get home?

    My thought is, have each section end in a low bulkhead so its top edge is above the waterline, then there is no need for perfect sealing. The seal whould be good enough so the boat can be bailed without refilling faster than the bailer can work, but once the bulkheads are above the waterline leakage should stop. The bulkheads can be bolted together simply.

    What do you think?
     
  4. wardd
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    wardd Senior Member

    make each join with a seal in a canalure like an O ring and a piece of bicycle inner tube to act as a seal, then you wont need bulkheads, the inflated tube will seal.

    I'd use a pressure gage to keep an eye on the seal pressure

    it sounds more difficult than it is
     
  5. ancient kayaker
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    ancient kayaker aka Terry Haines

    Good idea: the inner tube would have more range to accommodate damage or creepage than a non-pneumatic seal. The inner tube would need to be cut and the ends sealed: I guess ordinary rubber adhesive would be OK for that.
     
  6. apex1

    apex1 Guest

    Terry
    A round Neoprene or Perbunan cord will do the trick easier imho.
    http://telle.de/index.php?id=138&L=1
    http://www.ekibv.de/moosgummi.htm

    Regards
    Richard
     
  7. ancient kayaker
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    ancient kayaker aka Terry Haines

    That looks and sounds like a swimming pool noodle!
     
  8. apex1

    apex1 Guest

    :) yeah, a bit. But is thinner and stronger.
     
  9. cor
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    cor Senior Member

    I think that a 1/4" round rubber piece (from o-ring material) would make a fine gasket for the joint in a sectional boat.

    The forces on the joints are rather high. I would estimate that the bottom could see a tension load as high as 3000 lbs. This assumes a boat that is 24' long and 24" deep with a 500 lb load in the middle. If you pretend that the boat is a simple beam supported at each end (like having the bow up on a steep bank and the stern in the water).

    Cut a groove into the face of one section, glue the o-ring in and bolt it up to the next section. I do not think that you need a gasket with a lot of movement, if your joint is moving the boat is going to fall apart.

    I would use bolts with plate washer that you could drop into slots, rather than putting them through holes. The nuts could stay on the bolts and only have to be tightened or loosened a little bit. It would make assembly much easier.

    C.O.
     
  10. wardd
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    wardd Senior Member

    A couple advantages of the tube is replacements can be gotten almost anywhere, the grove for it doesn't have to be made to a high standard as long as it's smooth and wont puncture the tube

    to join the sections an aluminum strap a couple inches wide with one inch holes in it every few inches could be glass bonded to the inner hull with attachments welded to the ends at the joins, to be bolted

    would only take a few minutes to join the sections with a ratchet wrench
     
  11. ancient kayaker
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    ancient kayaker aka Terry Haines

    The gasket needs a certain thickness to take up flexing, which is going to happen to the mating ends of the sections even if the mechanical joint itself is stable. That results in a discontinuity around the hull exterior which is going to generate some turbulence, and therefore drag.

    If the gap is eliminated there would be no space for a seal. However, a thin (not necessarily adhesive) tape can be run around the joint, sheer to sheer, to provide a smooth surface across the transition. Hydrostatic pressure should create a seal. Very simple and easy to do, but I'm not sure I would want to trust my life to it.
     
  12. wardd
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    wardd Senior Member

    the inflatable tube idea i got from jet fighter canopies
     
  13. ancient kayaker
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    ancient kayaker aka Terry Haines

    The tape idea I got from shrink-wrapped groceries: a bit more mundane :)
     
  14. wardd
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    wardd Senior Member

    would minor flexing stretch and or tear the tape?
     

  15. ancient kayaker
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    ancient kayaker aka Terry Haines

    Possibly, but if there is no gap between the sections it should be possible to have them rigidly attached together, since there is no elastomeric seal between them. If flexing can be eliminated the tape may be OK. You could use duct tape but it would look icky and the stuff I get won't let go!

    No paddler with a wood kayak or canoe should leave home without it! Discovery TV channel have done some interesting things with duct tape, including building a working, 2-man sailboat and lifting a car.

    I was unable to get hold of my favorite double-sided outdoor carpet tape so I used duct tape to make my last sail from a tarp. I rolled it with the adhesive outside (dah) and used the tube like double-sided tape: it worked!
     
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