plywood transom/stringers?

Discussion in 'Materials' started by stilloutoffocus, Jun 12, 2009.

  1. stilloutoffocus
    Joined: Apr 2009
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    Location: Evansville, IN

    stilloutoffocus dealership repair flunkie

    im pretty sure i already know the answer to this one, but has anyone here had success laminating treated plywood with polyester resin and fiberglass?
    most sources ive seen say that you have to have epoxy to get a good bond with treated, and we have always used regular sheathing ply with poly for our transoms and stringer jobs. but the old man say that he has had good luck laminating treated wood with poly. my boss even says that the manufacturers are now using treated ply with poly laminate for transoms now.
    does anyone have any info or opinions on this?
    thanks much for your input
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    There are a couple of manufacturers of treated marine ply. I don't know if there is any difference. The new treated wood all has borates instead of copper arsenate. It is much more higroscopic (absorbs water) so I would think you got to be really careful about drying it.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The new CA treatments that have replaced the CCA in PT products doesn't take well to polyester or epoxy.

    In other words, don't use treated plywood or dimensional lumber unless you rely on a very aggressive mechanical bond.

    I don't know of any manufacture that is using PT plywood in transoms or stringers. Your boss sounds typical and over stating what he doesn't fully understand.

    Is there some part of my previous post on your other threads about this issue, that I didn't make clear Stilloutoffocus?

    http://www.boatdesign.net/forums/materials/protecting-plywood-polyester-resin-14325.html

    The new PT treatments seal the "pores" of the wood, so anything trying to penetrate can't. You can "tooth" up the surface, but the bond is inferior. And yes, drying the material is more difficult then the old CCA treatments.
     
  4. ondarvr
    Joined: Dec 2005
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    ondarvr Senior Member

    There is still CCA treated ply for marine use, it works well and many boats are made with it. Greenwood XL boat panels is one brand.

    Don't have time to list more info right now.
     
  5. stilloutoffocus
    Joined: Apr 2009
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    stilloutoffocus dealership repair flunkie

    well PAR i do remember your posts on a thread i commented on earlier and i did understand you. but you are not the only source of information on this site, and while i do value your input i feel that the only true path to understanding of an issue is to get information from as many sources as possible and find the truth somewhere in the middle. so while you obviously do have a great deal of experience and knowledge in boat building design and repair no one knows everything. and while my boss does like to act like he knows everything although most of it isnt true. he has been a sea ray dealer for the better part of 50 years and does know a little about their construction. and of course when it comes down to it i have to make do with the materials i am provided, regardless of how much i may try to enlighten my superiors to the errors of their ways.
     
  6. Dan H
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    Dan H Junior Member

  7. stilloutoffocus
    Joined: Apr 2009
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    stilloutoffocus dealership repair flunkie

    no, dan , what i was given is just pt ply from lowe's
     
  8. Manie B
    Joined: Sep 2006
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    Manie B Senior Member

    stilloutoffocus some of us wont reply (such as myself) once a very knowledgeable PAR has given an outstanding reply, i may from time to time add my 2 cents.

    do yourself a favour and go and experiment

    then you will also come back and say thank you PAR
     

  9. stilloutoffocus
    Joined: Apr 2009
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    Location: Evansville, IN

    stilloutoffocus dealership repair flunkie

    i thought i was clear in stating my appreciation for PAR's advice and i do hope to hear from him on future posts as well as he is, as i stated before, very experienced and knowledgeable. but. no one man knows everything about any subject, and it is my experience that there are as many methods of FRP work as there are workers. i was only trying to find as many opinions on the subject as possible.
     
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