flexible plywood

Discussion in 'Materials' started by 3333feet, Nov 21, 2011.

  1. 3333feet
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    3333feet Junior Member

    Hi everbody,Can we use a flexible plywood (out of marine ply)with epoxy coating? thanks
     
  2. PAR
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    PAR Yacht Designer/Builder

    Can you describe what your are doing a little better? The type of product, it's application, etc. as your question is so bland and broad that any answer is all but imposable.
     
  3. Dirteater
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    Dirteater Senior Member

    3333,
    you can, my boat is marine plywood and epoxy. the flexability depends on the the size and thickness of the wood. PAR raises a good question though.
    without knowing more about the type of boat and wood/fibre application is difficult to answer your question with much accuracy. Do you have any more thoughts or details?

    DE
     
  4. 3333feet
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    3333feet Junior Member

    you're absolutely right. I would like to build a 6-m cat. already have in my hand a flexible plywood.them under the body, I think using a steep incline.if you can provide water-tightness, can i use flexible ply. thanks
     
  5. Dirteater
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    Dirteater Senior Member

    flexible ply?
    6 m cat? do you have plans for this design?
    It sounds like a pretty big project to me. As far as being water tight that all, depends on how you glue and fiber your marine plywood joints, etc,. (if thats part of the plans). as i mentioned earlier you can certainly build a boat with marine ply and fibre and epoxy. so the answer is yes. My concern now is that you have good plans to go by. Sorry 3333 but I'm not sure what stage your at with the build.
     
  6. PAR
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    PAR Yacht Designer/Builder

    3333, you need to level the playing field, so we know what you're talking about. What is the year, make and model of your boat What is the design if you're building it? What is the project scope (what you're doing) in terms that we can understand? What is "flexible plywood" (scored?), what "steep incline" are you referring to, and under what "body" are you talking about, as these are common yacht terms, so we don't have a clue as to what you are referring.
     
  7. 3333feet
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    3333feet Junior Member

    I'm sorry for my english. I mean bottom of hull (under the waterline) curve area. I design 6 m cat, and built it, ıf I cant use flexible ply, I will change design parameters and construction. not yet been directing the work.
     
  8. PAR
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    PAR Yacht Designer/Builder

    Plywood curvature is a fairly predictable thing. We still don't know what you mean by "flexible plywood", as all plywood is pretty flexible, again within established minimum radius guidelines.

    Most folks think of "flexible plywood" as a pre-scored product, that can accept considerably more curvature, then a non-scored panel. These pre-scored panels can be purchased or home made, by using shallow saw kerfs. As a rule kerfed or pre-scored panels are considerably weaker then a continuous plywood sheet and typically are used within a laminate as a core.

    As to the suitability of these types of projects, it depends on the hull shapes you're trying to get. Generally, cylindrical and conical shapes are employed in sheet goods construction methods. These "developed" shapes are standard engineering principles, well established and understood for the most part. If you're having difficulty with this, then I'd suggest you brush up on materials understanding and physical properties.

    If you can post some wire frame or dimension view drawings, we can have a look and see if you actually need consideration, in regard to the curvature in the rocker of the hulls. Hull sides also come under the same "developed shape" rules as hull rocker.

    Post some line drawings and we'll have a look, to see what you can get away with.
     
  9. michael pierzga
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    michael pierzga Senior Member


    "Flexi plywood " is plwood fabricated with all its grain going in the same direction. Flexi ply is common in the furniture industry. Ive never seen Marine grade Flexi ply. Its possible to use it as a core but I have no knowledge of its use as a hull material.
     
  10. 3333feet
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    3333feet Junior Member

    ok Par, thanks.
     
  11. outside the box

    outside the box Previous Member

    http://wavelengthmultihulls.com all about the build of the Wavelength 780 tri built in Auz with the flex ply method. We also use it when prototyping good inexpensive product.
    Enjoy
     
  12. 3333feet
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    3333feet Junior Member

    thanks to 'out,
    I have a another question,
    can we use "Oriented Strand Board, OSB" other place of hull , for xample deck, construction
     
  13. PAR
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    PAR Yacht Designer/Builder

    OSB has no place on a boat. It's heavy, not especially strong for it's weight, though you can use it in furniture and other internal elements, there are much better choices then OSB.
     
  14. ancient kayaker
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    ancient kayaker aka Terry Haines

    A wood product with its grain more-or-less oriented in the same direction to enhance flexibility is going to lack strength across the grain and as-is will not be suitable for boat building. A simple coating of epoxy will not add the missing strength, that would require a layer of fiberglass, or better still fiberglass on both faces.

    It might be better and cheaper to achieve the curved surface using strips of wood, which is an established method called strip-building or strip-plank composite. A cat will have narrow hulls that will suit this method.

    Other established methods of building cat hulls include tortured ply, constant camber, cold-molding and cylindrical molding. You can find descriptions of these methods on the web.

    This link addresses them all http://www.journeyman.cc/~simon/boats/slippery/slippery_0_2.html
     

  15. pauloman
    Joined: Jun 2010
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    pauloman Epoxy Vendor

    there are flexible epoxies, even 'rubber epoxies'. Typical marine epoxies are brittle with little or no flex. Also things you can add to increase epoxy flex (at least for a while).

    progressive epoxy polymers inc.
     
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