4'x20' pvc sheets for boat building

Discussion in 'Materials' started by rallyview, Nov 23, 2009.

  1. rallyview
    Joined: Nov 2009
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: virginia

    rallyview New Member

    I'm working at a lumberyard and we've started getting in these 4'x20' sheets of pvc. They come in 3/8, 1/2, 3/4, and 1". They have the same density/ weight as yellow pine plywood.

    My questions on the sheets are:
    1 will they deform and creep overtime due to the sun. how would you frame to minimize this? The panels i've seen are supposedly stable to 158 degrees F
    2 Would a pvc solvent glue like used in plumbing work give a flexible enough bond for boat construction. Would i be better off using a high temp plastic welder? Polyurethane, polyester resin? G-flex?
    3 I envision using these panels for stitch and glue designs. Will the large movement of these panels over the course of a heat cycle be a problem? Since the whole hull will be built of the same material i think material movement will not be a problem but maybe i'm overlooking something.

    any thoughts?
     
  2. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 470, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Take one of these PVC sheets and make structural comparisons to the same thickness plywood. What you'll find is it's not as stiff and several other physical short comings. Couple this with PVC's difficulty in UV break down, ability for paint to stick to it and adhesive issues, makes it a poor material for planking as you suggest.

    One of the biggest elements of stitch and glue construction are the seam reinforcements, replacing traditional longitudinal structural elements. This is done with fillets and fabrics set in epoxy. PVC cement can't do this. You could heat weld to a frame, but you'll lose the weight savings advantage of stitch and glue, coupled with the other stuff, making you wonder, why bother.

    Give it a try, but you'll find that very little sticks to it well, it's not self supporting for it's weight, is heat sensitive (lots of movement), etc., etc., etc.
     
  3. JRL
    Joined: May 2007
    Posts: 83
    Likes: 2, Points: 0, Legacy Rep: 25
    Location: Palm Beach Gardens, FL

    JRL Im with stupid

    This article was helpful to me when deciding to use PVC. Im only making a casting deck with it on a very small canoe. Poly supposedly sticks to it (am testing that at the moment: 45 grit sanded surface, CSM, Poly layup). If all else fails Ill use it in the same manor as Bertram (i.e. nothing to structural).

    http://www.bertram31.com/proj/tips/pvc.htm
     
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