help flat bottom designs

Discussion in 'Boat Design' started by ozaffect, Jun 22, 2011.

  1. ozaffect
    Joined: Jun 2011
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    ozaffect Junior Member

    thank you for everyones help i finally decided on building a 15ft skiff as it does what i need.

    now for a really daft question.. plywood? will extior ply do the same as marine ply never worked with ply always worked in real wood so not a clue? ....
     
  2. ozaffect
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    ozaffect Junior Member

    can extoir ply be used
     
  3. pistnbroke
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    pistnbroke I try

    Exterior ply is ok ..its going to be coated in expoxy any way ...Polyester resin does not stick to ply very well so you need epoxy for the joint ..though in my opinion you can sheath the outside in poly resin ( its much cheaper buy on e bay ) If you read Hannu's boatyard you will see he uses any old ply and just oils it ...depend if you are leaving it outside or on the water ... 1/4 ply is way enough except for the transome ..keep the weight down !!!

    If you want to design it yourself you can use Carene software and then import to freeship and print out the panels.....
     

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  4. PAR
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    PAR Yacht Designer/Builder

    Any plywood can be used, though if the boat has much "shape" exterior plywood will usual show why it's not used much except in really low cost applications. It's not designed for dynamic loads and can fail unexpectedly. My usual recommendation is marine grades only on hull planking. It's the material that will keep you socks dry and generally is some of the best on the boat, if professionally built.

    Designing a boat yourself wouldn't be a recommendation I'd suggest. There's just way too much information you need to absorb to have a reasonable outcome. The software packages now available can make some pretty pictures of boats, but it doesn't tell you if the shapes you've selected are well suited to your needs. Considering the hundreds of designs available for a boat in this size range, you're so much better off, just buying a set of plans and following the engineering in them.
     
  5. pistnbroke
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    Well thats PAR somewhere up in the clouds in your terms ..you want a cheap boat to enjoy building and using quick ..god the english summer has almost come and gone ( in april ) ..have a look at www.saving-old-seagulls.co.uk in sectiion boats suitabe for seagulls ...HA builds them in a couple of days for silly money and has fun or ..look at hannu's boatyard ..... a 12 ft boat..... EPLS .......( dont put a seagull on it they are out of date rubbish and dangerous ie no FNR )
     

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  6. LP
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    LP Flying Boatman

  7. p_smith
    Joined: May 2010
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    p_smith Junior Member

    come on Oz, skip the plywood, you've worked in real wood, and are familiar with it, and probably enjoy and appreciate it. Even quality ply is dull compared to the real thing. Go for a traditional build! Cross plank bottom tight fit with no caulk and two nice planks carvel planked on the topsides. I believe you'll enjoy the build and finished product much more than a big hunk of plywood.
     
  8. p_smith
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    p_smith Junior Member

  9. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    forget all this old plans crap ..would you buy a 1930 Humber ,,,no ...go ply and epoxy ..get with it get modern ...get a LIFE..just back woods americans trying to impose there will on the world again .......Bush lives
     
  10. PAR
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    PAR Yacht Designer/Builder

    That's traditional file planking and something I'm very familiar with, but it's heavy, has many dozens of potential leak points and is difficult to fair. If you hook up a gas engine to this type of bottom, it will leak like a bottomless bucket (file planking doesn't tolerate vibration or wracking). A couple of sheets of plywood, will easily cover this bottom (the one shown in the link) and have only a couple of potential leak points, will be stronger, can tolerate vibration, wracking, it's lighter, requires much less fitting and fiddling, etc., etc., etc. In short, plywood and hard chine hulls are naturals, particularly flat bottoms. If you want a traditional build with antique building methods, use the file plank system, but if you don't want to fuss with the hull after it's built, use plywood.
     
  11. pistnbroke
    Joined: Jan 2009
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    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    This guy is going on a british canal ..12 -14 ft wide and is unemployed ....
     
  12. p_smith
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    p_smith Junior Member

    :D lol, better just to walk along the bank then instead of getting into a plywood boat!
     
  13. troy2000
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    troy2000 Senior Member

    Depends on what he wants. If he wants to give his woodworking skills a workout and build a piece of wood sculpture, either for his own pleasure or to impress others, fine. Go for the traditional methods. I won't knock him for it; it's the sort of thing I would enjoy also.

    But if he's looking for a practical, easier-built and more watertight boat, methods and materials have come a ways in the last hundred years or so. And if his boat will spend a good part of its life drysailed on a trailer, he'd be remiss not to at least consider plywood--for the bottom, if nowhere else...
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    He can install skids and bottom strakes to protect the planking. He can also use a double layer of plywood, the outer being sacrificial in nature.
     

  15. rberrey
    Joined: Oct 2010
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    Location: AL gulf coast

    rberrey Senior Member

    Bateau has some nice designs that might fit your needs
     
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