using veneer in ply butt jointing

Discussion in 'Boatbuilding' started by fabrice, Dec 10, 2010.

  1. fabrice
    Joined: Mar 2009
    Posts: 54
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Poitiers, France

    fabrice Junior Member

    I'd like to use butt joints instead of scarfs in my plywood pirogue, in order to keep the overall length (my ply is rather short).
    I wonder if there is another method than the usual.
    I saw some people using fiberglass with epoxy instead of epoxy glued plywood bits.
    Having a batch of veneer wood, would it fit the purpose ?
     
  2. gonzo
    Joined: Aug 2002
    Posts: 13,288
    Likes: 323, Points: 93, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    You can scarf with fiberglass. On the outside, grind a shallow bevel so that the surface end up smooth after you laminate the fiberglass over it.
     
  3. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 470, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    It's called the Payson butt joint.
     
  4. fabrice
    Joined: Mar 2009
    Posts: 54
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Poitiers, France

    fabrice Junior Member

    OK, what about gluing wood veneer instead of fiberglass ?
     
  5. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 470, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    A veneer will not give you much strength, particularly in the cross grain orientation. Even if you use very thick veneers, such as .125" (3 mm), you wouldn't have much strength. On the other hand if you topped off a fabric reinforced Payson butt joint with a veneer, you'd have the strength necessary, but I fail to see the rational behind adding a veneer to a product that is made of veneers.

    What is your logic behind employing a veneer in a scarf?
     
  6. fabrice
    Joined: Mar 2009
    Posts: 54
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Poitiers, France

    fabrice Junior Member

    I have got a handfull of veneer, and was wondering if it could actually replace the glass fabric.
     
  7. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 470, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    No, the veneer can't replace the fabric.
     
  8. Steve W
    Joined: Jul 2004
    Posts: 1,800
    Likes: 55, Points: 48, Legacy Rep: 608
    Location: Duluth, Minnesota

    Steve W Senior Member

    On a small boat like a pirogue just a layer of 2" glass tape inside and out of the butt on the surface will surffice and blend it in with a little filler before you paint it, no need for any grinding away of the wood. Even though a light uni would be better just the regular balanced weave tape that you may have on hand if your doing stitch and tape will create a butt that will be more than strong enough.
    Steve.
     
  9. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 470, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Maybe you can live with a 1" overlap on 1/4" plywood, but this is pushing it for me, though very lightly loaded, you're right it would do. Counting the taped edge, you'll need more then "a little filler" to hide it.
     

  10. Steve W
    Joined: Jul 2004
    Posts: 1,800
    Likes: 55, Points: 48, Legacy Rep: 608
    Location: Duluth, Minnesota

    Steve W Senior Member

    I was first introduced to the simple glass tape butt almost 30 years ago when we were hired by a Minnetonka company to refine the production of a line of 13 stitch and tape small boat kits which had been developed in England by Bell Woodworking, dinghies,canoes,kayaks,beachcats, lots of very good designs, many by Jack Holt. Anyway they imported one of each kit which came with polyester resin,1 1/2" glass tape etc and in the instructions were the directions for doing the butts as i described. We of course switched to epoxy and 2" tape and built dozens of completed boats and hundreds of kits and it works fine, no need to make it any more complicated. If you feather out the selvege edge it fairs in fine,no different to the chines,keel,stem etc.
    Steve.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.