birdsmouth oars

Discussion in 'Wooden Boat Building and Restoration' started by txriverrat, Jun 28, 2012.

  1. txriverrat
    Joined: Sep 2010
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    txriverrat Senior Member

    I have built some paddles but never a oar or a birdmouth type shaft. So I figure there is no time like the present so here we go.
    Had some cedar strips 1/4 thick so I ripped the 45% angle in the edge.

    [​IMG]

    did this to seven pieces and the glued them up with tit bond II



    [​IMG]

    The zip ties work well to hold them together.

    view from one end

    [​IMG]

    after they dried I took a plane and rounded them up.
    Ron
     
  2. PAR
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    PAR Yacht Designer/Builder

    Had you made it an 8 stave piece instead of 7, it would work, with tight joints. With only seven pieces and a notch cut at 45 degrees, you're off in each notch by 6.43 degrees, which frankly is a huge amount and certainly not enough to offer TiteBond II, a good enough mating surface to bond well. Conversely, had you canted the notches at 51.43 degrees, instead of 45, you'd have perfect mating surfaces and the non-gap filling TiteBond II, would have a chance at holding those shafts together. Even though the picture is poor quality, you can still see the huge gaps and incorrect angles employed. Good luck with those, stay near shore or bring spares along with you.
     
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  3. txriverrat
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    txriverrat Senior Member

    glued up some scrap cedar and turned the handles and plugs

    [​IMG]

    glued them in

    [​IMG]

    then I glued up the blades and ran them through the planer

    [​IMG]

    After gluing in the plug I thinned some tite bond and poured it into the shaft rolled it around and coated the inside.
    Ron
     
  4. txriverrat
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    txriverrat Senior Member

    Par
    I didnt like the size so I dropped one piece, but there are a couple things I will do a little different on these to make them hold up well.
    Ron
     
  5. waikikin
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    waikikin Senior Member

  6. PAR
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    PAR Yacht Designer/Builder

    If you're thinking epoxy will help, the joints are lathered up with PVA, which epoxy doesn't like to stick to. PVA's (TiteBond) aren't gap filling and require fine fitted joints or it pretty much sucks. Lastly, TiteBond II is only water resistant (type 2 WPB), so immersed, the joints will tend to come apart. PVA's also tend to creep under load and especially if moisture content softens the glue, so . . .
     
  7. gonzo
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    gonzo Senior Member

    I agree with PAR on this. The angles are not right for seven pieces.
     
  8. txriverrat
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    txriverrat Senior Member

    Like the info yall are throwing out.
    If I have to trash these it will be a good learning experience ,I figure by the time I get to be an old man I will be a smart ole far$.
    These are all scrap wood so I have less than 10.00 in both shafts . I will finish them with a couple add ons to increase the strength and then try to break them , bet I can make them work.
    Ron
     
  9. frank smith
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    frank smith Senior Member

    I think that "getting to be an old man" part , is a good plan .

    Frank
     
  10. Petros
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    Petros Senior Member

    Tightbond II works okay for laminating paddles, I have used it without issues. put 5 to 7 coats of exterior varnish no them to minimize the amount of mosture the glue joints get, and it should work fine.

    Paddles are not kept or stored underwater, the amount of moisture exposure is very small for most paddlers. If the paddles are stored indoors the bond will hold up fine.

    The gap in the joints is a different matter, it appears only half of your joint will actually hold, which may be enough since these joints are only loaded in indirect shear. The foaming polyurethane glue (like "Gorilla" glue) would have been a better choice if you knew the joints were going to have larger gaps.

    If you decide to keep these, than perhaps filling the gaps and than putting a layer of fiberglass over the outside might be a way of solving the problem. Otherwise you can make up another pair with the correct angle, and I would advise to use Gorilla glue or epoxy instead.
     
  11. PAR
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    PAR Yacht Designer/Builder

    This assumes tight joints with well match mating surfaces and sufficient clamping pressure, plus a good moisture seal (varnish/polyurethane) over the whole shebang, when completed. We have substantially less than this here. Maybe some hose clamps spaced along their length, just in case.
     
  12. txriverrat
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    txriverrat Senior Member

    Ok here we go again.
    first if this was a mast ,oars for an expedition , 12 ft long , I would be worried.
    These are learning first time knock around oars for local fresh water.
    Tite bond II I have used in nearly 20 boats with zero problems , These oars are 7 ft tip to tip.
    I did one thing today that should really increase the strength of these units, I turned four plugs one inch long and installed them inside the shaft,so basically there is not more than a 14 inch span anywhere on the shaft that isnt braced.
    Cut a slot 1/4 deep on the side of the shaft

    [​IMG]

    glued on the blade.

    [​IMG]

    layed up another piece of cedar for the blade brace.

    [​IMG]

    Ron
     
  13. txriverrat
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    txriverrat Senior Member

    Trimed the tip piece , it laps inside the shaft for an inch and a half.
    here is one I am fitting

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    one glued in place

    [​IMG]

    then I started sanding and finishing the shaft.
    Ron
     
  14. upchurchmr
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    upchurchmr Senior Member

    Might as well finish and see how long they last.
    Then you can take the suggestions here.
    I built some shafts but havent finished the paddles.
    If you want a smaller diameter, use a smaller width of 1/4" strips.
    I started with 1/4 x 3/8 strips and the shaft was very small.
    1/4 x 3/4 was very big
    1/4 x 1/2 was a little too large for my hand, so.....
    Next time will be perfect with 1/4x 7/16.

    Or you could use the calculator shown above and get the same thing.
    Do use 8 strips, you will be surprised how much better everything fits.

    I am probably a little farther north in Texas than you.

    Marc
     

  15. txriverrat
    Joined: Sep 2010
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    txriverrat Senior Member

    I had 8 strips cut glue on them when I realized it was going to be way to big ,thats why I dropped to seven.
    I have some expertise with yaks but non with a boat that uses oars so this is all a learning experience for me. I appreciate the suggestions and advice.
    Waco here
    Ron
     
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