How to calculate wood width?

Discussion in 'Boatbuilding' started by stonedpirate, Nov 29, 2009.

  1. stonedpirate
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    stonedpirate Senior Member

    Hello,

    I am going to build a stitch and glue boat and was wondering how to choose marine ply thickness?

    Is there a calculation to determin strength require or bending ability?

    Just not sure what to buy.

    Thanks
     
  2. alan white
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    alan white Senior Member

    The question seems out of place. On the one hand, if you have designed the boat yourself, you already know enough to decide the ply thickness, but on the other hand, if you are using purchased plans, they should specify ply thickness.
    Plywood thickness is chosen based on a huge number of design considerations. Boats are built light and fast or heavy and slow and everything in between.
    Let's say you're designing your own boat. If you look at the specs for ten boats in the same size range you'll notice a large difference in weight between them. If the ten boats are made from plywood, you'll see the lightest has a hull thickness of perhaps half that of the heaviest.
    I suggest you provide more information. Drawings would help. Intended use would also help (racing, fishing, planing, drifting, paddling, or what have you).
     
  3. stonedpirate
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    stonedpirate Senior Member

    Thanks a lot Alan.

    Good points.

    So it is a trade off between speed and strength.

    I'm not interested in going fast.

    I am trying to build an 8 foot indestructable hull capable of circumanavigation like the one below:

    [​IMG]

    [​IMG]
     
  4. TeddyDiver
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    TeddyDiver Gollywobbler

  5. PAR
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    PAR Yacht Designer/Builder

    Ferro cement . . . and a serious education in yacht design, plus a good dose of structural engineering . . .
     
  6. stonedpirate
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    stonedpirate Senior Member

    I read it was a stitch and glue.

    Might just by some ply and kick it to see what it can handle :p

    Trial and error.
     
  7. alan white
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    alan white Senior Member

    For something like that, two layers of 3/8" plywood maybe, offset by 30 degrees? Wood would give some insulation.
    I feel seasick already.
     
  8. gonzo
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    gonzo Senior Member

    Remember a watertight compartment for the crack.
     
  9. wardd
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    wardd Senior Member

    that would also make a great coffin
     
  10. daiquiri
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    daiquiri Engineering and Design

    How do you pee and poo in that thing?

    After few weeks in that box your backbone will hurt you for the rest of your life, I think...
     
  11. Manie B
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    Manie B Senior Member

    Gonzo have you been drinking?

    Remember a watertight compartment for the crack.
    And the power supply for the concrete, you really bowled me over
    very good keep it up:D
     
  12. gonzo
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    gonzo Senior Member

    Are you willing to start a manufacturing plant in SA?
     
  13. stonedpirate
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    stonedpirate Senior Member

    Somebody has to beat Serge Testa.
     
  14. Manie B
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    Manie B Senior Member

    It could be done :D that was my job ;)
    but your financiers / investment team will hate me
    I have headed a number of feasabilty studies in my life (= a reality check)
    and when i rain on their parade they get VERY pissed off (call me negative):p
    years later they thank me - usually at the "yot club" :D
     

  15. stonedpirate
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    stonedpirate Senior Member

    Poms and south africans.

    i dont know..
     
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