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Bending gunwales

Discussion in 'Wood and Canvas' started by ticonderoga, Oct 19, 2011.

  1. ticonderoga

    ticonderoga "Just one more"

    When steam bending gunwales ( in or outer) for a canoe with quite a rise at the stem, what is the best way to orientate the grain? Should it be flat, ie visible from the sides or on edge ie visible from the top? thanks.
     
  2. Paul Miller

    Paul Miller Canoe Nut

    The edge grain should be oriented up and down, which may be the opposite of what you might think. The screws though the gunnels will then be drilled perpendicular to the grain for greater holding, vs. with the grain which will cause it to split.

    Good luck,

    Paul
     
  3. chris pearson

    chris pearson Michigan Canoe Nut

    Hmmm, I always went the other way, rings parallel to the bend. Thats the way I remember seeing allot of Old Towns. Although, Rollin can pipe in here, I think I remember him saying it surprisingly doesn't matter?
     
  4. Dylan Schoelzel

    Dylan Schoelzel born in a canoe

    Which way to orient the grain for steam bending is a debated topic that really has no right or wrong answer. Sometimes the nature of the work will dictate this and other times the wood itself will decide. Mostly it boils down to personal preference and experience so here my take on it.

    From a sheer steam bending perspective, taking no other factors into account, I prefer to orient the vertical/edge grain parallel to the bend. In the case of outer gunwales this would put the edge grain along the sides of the gunwales. I find that most species bend with less resistance when the grain is oriented this way. It also lessens the chance of compression failure.

    If you decide to orient the vertical grain on the side of the gunwale I would not worry about the wood splitting when fastening. Sure the chances are a little greater when grain is oriented this way, but splitting usually occurs at the fault of the person doing the fastening.

    As long as proper screw piloting and tightening of the screw are exercised you won’t have too much to worry about. Think about all the hundreds of thousands of boats and canoes built with vertical grain planking, ribs, frames, decks, gunwales, etc that have their fasteners, whether screws, rivets, clinch nails, bolts, etc, oriented parallel to the vertical grain and have held up fine. Some for over a century.

    The wood of the outer gunwale is not providing much, if any, holding power for the screw to secure it to the hull. The ribs and inner gunwales are the members providing the holding power.

    If you were to examine the profile of a typical outer gunwale and how a screw is fastened through it, you will notice that the shank of the screw, the unthreaded part, is the part of the screw that is set in the outer gunwale, not the threads.

    A screw derives its’ holding power from the threads so the more important part to securing outer gunwales is not the wood of the outer gunwale, but what the threads of the screw are biting into.
     
  5. Douglas Ingram

    Douglas Ingram Red River Canoe & Paddle

    I can't tell you how many gunnels I've worked on (many!), but I can tell you that there does not seem to be a consistent approach to this issue.

    Dylan, NICE SHOP! I'm more than a little jealous...
     
    Last edited: Oct 25, 2011
  6. Rob Stevens

    Rob Stevens Wooden Canoes are in the Blood

    And a great lineup of canoes. Glad I finally noticed your blog, Dylan.
    Douglas' "Wood Be Creative" is one of few others I follow.
     
  7. merk

    merk Curious about Wooden Canoes

    With that said, and thank so much for this. This is my first pair of new gunnels. I have always reused outer gunnels in the past as they were in good shape. So I am inexperienced, so could someone send me a link or photo of the bit or bit combo best suited to drill the holes once the gunnel is set in place. Thanks

    I think I will setup to steam in the plastic bag method in the videos unless someone supports the idea of just soaking them in the pond! :eek:) Which is very easy compared to steaming...


    [QUOTE="The wood of the outer gunwale is not providing much, if any, holding power for the screw to secure it to the hull. The ribs and inner gunwales are the members providing the holding power.

    If you were to examine the profile of a typical outer gunwale and how a screw is fastened through it, you will notice that the shank of the screw, the unthreaded part, is the part of the screw that is set in the outer gunwale, not the threads.

    A screw derives its’ holding power from the threads so the more important part to securing outer gunwales is not the wood of the outer gunwale, but what the threads of the screw are biting into.[/QUOTE]
     
  8. Dan Miller

    Dan Miller cranky canoeist Staff Member

    Soaking in the pond first, and then steaming in the poly bag is never a bad idea. It never hurts to up the moisture content in the gunwales prior to bending.

    If you want a combo bit, then get a Fuller tapered bit with a countersink and depth stop. If you want to do it more better, drill first with a bit of the root diameter of the screw, then clear the outer gunwale hole with a bit the same diameter as the screw shank, then follow up with the appropriate countersink.
     

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