scarfing green wood

Discussion in 'Wooden Boat Building and Restoration' started by Collin, Jan 30, 2012.

  1. Collin
    Joined: Nov 2011
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    Collin Senior Member

    I bought some green 2x4s to scarf into gunwales for a skin on frame boat I'm building.

    I've been sitting on them for a month and they're still carrying a lot of water and I'm realizing it's going to take 6 months for them to dry out.

    Building with green wood is fine in SOF, but I'm nervous about scarfing green wood and that effecting the joint's strength down the road when the wood dries out.

    I've cut the scarfs to encourage the wood to dry faster, but I have no idea if I'm going to end up with weak gunwales if I glue them now?
     
  2. gonzo
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    gonzo Senior Member

    When the wood dries, the scarfs will no longer fit. If you want to dry the wood faster, build a kiln. If you glue them now, it will likely fail at the glue joint. Also, invest on a moisture meter.
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    2x4 wales are pretty huge for a SOF build. Rip the stock to the dimensions you need, which will expedite the drying process. I can't imagine them needing to be more then 1x2's, more likely smaller.

    You can build a solar kiln, which will dry 1x2's in about a month. Don't glue the stock until it's dry enough to be reasonably stable, which is below 18% (minimum), below 16% is much better, especially if gluing with epoxy.
     
  4. Collin
    Joined: Nov 2011
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    Collin Senior Member

    That's true. It's time consuming to rip all the pieces to dimension and then scarf 30 pieces together. It's much quicker to scarf 6 or 8 big pieces and then cut them to size.

    I'm going to be using probably 1/2'' gunwales x 3'' or thereabouts. I'm trying something different and building a catboat SOF. Bending even 3/4 gunwales can be very difficult when you start building wider boats-and who knows how hard it's going to be to get them to conform to catboat dimensions.

    I'm going to have to find new wood, because in a month a skin boat should be pretty much done.
     
  5. cthippo
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    cthippo Senior Member

    I dunno, my first SOF took 15 months, though I used some strange construction methods. I'm not sure if the scarfs would survive the sawing process, but let us know how it turns out!
     
  6. gonzo
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    gonzo Senior Member

    A 1X4 is 3/4"X3 1/2". They are cheaper than 2X4s too. Run them through a planer to get the desired thickness. However, most SOFs have much lighther structures. Maybe 1X2 at the most.
     
  7. Collin
    Joined: Nov 2011
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    Collin Senior Member

    SOF can vary a lot. The first few take much longer than when you have experience. My first SOF boat used plywood frames and took 8 months to build.

    Using another person's design, clear wood and knowing the process speeds things way up.

    Scarf everything at once, cut all the stringers at once, be very careful with rib wood selection etc.
     

  8. Collin
    Joined: Nov 2011
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    Collin Senior Member

    I may have to go that route, but I would end up scarfing 4 pieces of wood and they may bend irregularly. This can mean a boat that's difficult to square up because one piece will be stiffer than the others.

    1x2 is good for a kayak, but a a 14 foot catboat with 7 foot beam is going to be generating a lot more stress on the frame. The gunwales not only need to bear the stress of the mast step, but have to hold the sheer (they'll have to be sliced lengthwise and laminated,) 1x2s wouldn't be able to do either of these things.

    This is a yacht tender I designed and built in SOF

    [​IMG]

    The gunwales are 1/2''x1 1/2''. I originally used 3/4'' gunwales, but when I was bending them in, one of them snapped. I steam bent the gunwales for the sheer, but the sheer straightened out and now it has practically none.

    (this boat only cost about $50 to build. minus the finishing and skin)
     
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