Would this idea work -a 14Ft Curved Bottom Plywood Boat

Discussion in 'Boat Design' started by N2dweb, Jan 26, 2010.

  1. N2dweb
    Joined: Jan 2010
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    N2dweb New Member

    Would this idea work :?:
    14Ft Curved Bottom Plywood Boat - only 4 seams. Materials 4ea sheets of 1/2” plywood 4x8 4ea Studs 2”x4”x8’
    Steps: 1. Scarf joint 3 of the plywood sheets to create a single sheet 8’x12’
    2. Curve sides by placing sand bags in the middle (4 feet on each side), allow a week or so until the plywood is uniformly curved. Looking for 18“ to 24” sag over the 8 feet.
    3. Cut and attach studs to top edge of plywood to brace and maintain the side curves to the boat.
    4. Cut and attach plywood to the stern of the boat
    5. Cut and attach plywood to the bow of the boat
    6. Apply epoxy coat
    7. Add additional support and trim
    8. Add a raised plywood deck to the bow of the boat
    9. Add seating and storage as desired.
    Below is a quick sketch:
    [​IMG]
    Plan on using the boat to fish in the back bays Galveston/Surside Tx.
    Thanks in advance!:?:
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    The bow (green) section is a bulb. Plywood won't bend to that shape.
    The hull has very little initial stability, it will be very tippy.
    It will have a very high resistance, that is it will be hard to move in the water.
    Overall it is a bad design with nothing to recommend it over a normal design.
     
  3. mcollins07
    Joined: Jan 2006
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    mcollins07 Senior Member

    It looks like you want ease of construction. The stability of such a round bottom would probably be a problem. Add one chine on each side and the construction will probably be easier and you will gain stability.

    How do you plan on powering the boat?

    check out PDRacer.com If you are using an outboard, then make the stern a less curved.
     
  4. messabout
    Joined: Jan 2006
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    messabout Senior Member

    You have presented your case with clarity. Sorry to tell you that this is an idea that is not worth further discussion. This will not be as easy a build as it might seem. Better to build in the tried and true manner and end up with a seviceable boat that has some lasting value.
     
  5. alan white
    Joined: Mar 2007
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    alan white Senior Member

    You won't curve 1/2" plywood to that radius without some serious wetting and jacking. Too stiff.
    N2dweb, you are approaching the art of boatbuilding from the wrong perspective. Though you are clever and have the rudiments of putting structures together, you might spend some time learning how others have done it. There are just too many issues you don't know enough about to consider.
    Anything can float and "go" to some degree, but here you can learn to do a lot better than just floating and going. To design and build a real usable boat that's light enough, fast enough, and practical to build and own, takes years of experience in the field. Yet you can buy plans from such a designer for peanuts.
    There's enough challenge to just building from plans.
     
  6. ancient kayaker
    Joined: Aug 2006
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    ancient kayaker aka Terry Haines

    You will get a much sharper bend in the middle of the scarfed ply sheet than along the edges, not what you want. But keep trying and asking questions! We all had to start someplace. One of my early ideas was a lot like this one. If you are dead set on building boats to your own designs rather than a professional's, start with models and progress to a few small boats first like a canoe or rowboat then move up. it's a faster and cheaper way to learn. But if you just want one boat then buy a plan!!!
     
  7. messabout
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    messabout Senior Member

    Well said Alan.
     
  8. JLIMA
    Joined: Oct 2009
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    JLIMA crazed throttleman

    Just curious why the round bottom? In your medium ie plywood a "vee" bottom is much simpler to construct and easier still is the flat bottom. Going along those lines a flat bottom and a simple "transom bow" that angles forward is a relatively simple build with out curves is much more stable and such boats have been used for years and get up on plane easily with a 10-15hp outboard. They are high suited to calm waters, and while I highly recommend a proper designer which I myself am not, such a boat is very simple to figure out. I apologize for bursting your bubble so to speak but plywood just can't be bend in the shape of the bow your intending in your sketch.
     

  9. ancient kayaker
    Joined: Aug 2006
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    ancient kayaker aka Terry Haines

    Actually the shape of the bow in N2's sketch can be achieved in ply. It's a cylinder with it's axis at 45 degrees so it appears to be a semi-ellipse in both the end and side elevations. However it creates a lateral chine across the bottom of the boat which will make for a lot of drag and turbulence.
     
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