Okoumi Plywood- slight bend an issue?

Discussion in 'Boatbuilding' started by mariobrothers88, Oct 31, 2020.

  1. mariobrothers88
    Joined: Sep 2020
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    Location: San Diego, CA

    mariobrothers88 Junior Member

    Hi guys, I purchased all the 9mm, 6mm, and 12mm okoumi plywood sheets I would need to build a woods catamaran and I have them stacked up against the wall. However, due to all the weight of the plywood, I noticed that the sheets have a slight bend. It's not a big deal so far since I can easily straighten them out with clamps. I am planning to make all the bulkheads first. However, by the time I get to the hull and interior, the plywood sheets would have been sitting like that for many months and I'm worried the weight might cause structural problems. I figure it won't be a big deal since I can probably just bend it back with clamps and it's going to get tortured on the hulls anyway. I would prefer to just lay all the plywood sheets flat on the ground so I won't have this problem but I am limited in terms of space. Should I take the time to make room to get all the plywood sheets nice and flat on the ground or am I being overly cautious and paranoid?
     
    Last edited: Oct 31, 2020
  2. Squidly-Diddly
    Joined: Sep 2007
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    Location: SF bay

    Squidly-Diddly Senior Member

    I'm a house carpenter, so I want plywood FLAT. If I need to leave leaned up for any time, I'll lean 3 or 4 2x4s against a wall then lean the plywood on the that so it leans flat without a bow. You might want to also put a few straps around the leaned stack to prevent any curling of thin plywood. I'd buy a nice piece of 7/8" plywood and lean that as last piece to sorta press everything together against the 2x4s. (the 7/8" will be a nice big shop table top later.)
     
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  3. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Senior Member

    Or flip the sheets over every couple of weeks. The odd weeks will reverse the bow acquired on the even weeks.
     
  4. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    And since the cause of the bowing is temperature and moisture changes, do what you can to slow those down. Don't set them on a cold floor, put a couple 4X4 chunks on the floor and lean the 2x4s up against the wall, then stand a sheet of thick cheap ply or foam, then your good plywood, then a cover sheet like squidly said. Keep temp and moisture changes to a minimum. A room dehumidifier is worthwhile in damp locations. I usually throw a sheet of plastic over the stack too.
     

  5. mariobrothers88
    Joined: Sep 2020
    Posts: 51
    Likes: 1, Points: 8
    Location: San Diego, CA

    mariobrothers88 Junior Member

    Hi guys, thank you so much for all the great replies! So I decided to move the okoumi plywood flat against the ground and I'm glad I did because I discovered an issue! Apparantly there were a bunch of holes in the tarp I had placed on the ground and there was a leak from the house that caused the ground to get wet. About 20 pieces of plywood have signs of moisture on the edge (see attached photos). It was only sitting like that for 10 days, I don't have to worry about wood rot do I? I went over it with a heat gun and I'm airing it out with a fan, but should I also use a fungicide? I live in a dry location and we haven't had any rain recently so humidity is pretty low.
     

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