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Thread: Fixing unfair steam bent keel

  1. #1
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    Default Fixing unfair steam bent keel

    I'm building the Herreshoff Dinghy which has a sprung keel. It's 1 3/8 inches thick white oak, which I steamed and bent over the molds.

    Unfortunately, the curve aft of station 7 is pretty tight and my bending didn't produce a fair curve as you can see in the picture below.

    20181108_160416.jpg
    *Note - I left the keel long for now, it will get cut so that it only extends about 2 inches beyond station 8.


    What's my best course of action to fair it out? Is it salvageable?



  2. #2
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    Default Re: Fixing unfair steam bent keel

    It looks like there was a knot very close to that hard spot in the curve. About the only way I could have seen making that stick work would have been to define the intended curve with a piece of wood between the moulds so it could have been clamped continuously along the curve (and clamp that high spot down).
    It would have to be steamed for this to work.

  3. #3
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    Default Re: Fixing unfair steam bent keel

    Spring a batten next to it and draw a pencil line. Maybe it is not as far out as it appears and can be faired.

  4. #4
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    Default Re: Fixing unfair steam bent keel

    Since steaming dries the wood, I'd soak it in water for a day or two, then resteam it and bend it with some extra support as nedL suggests.

    /Mats
    My blog about my time as a boat building student, a rigger apprentice and Journeyman http://kaptenmohsart.blogspot.se/

  5. #5
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    Default Re: Fixing unfair steam bent keel

    Or, you just build to the keel you have. The option would be to redo the keel.

  6. #6
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    Default Re: Fixing unfair steam bent keel

    I would steam another one. This early in the game, you want to get the best start possible.

  7. #7
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    Default Re: Fixing unfair steam bent keel

    I had the crazy grain around a knot near the end of an outer gunwale give me an unfair curve. I am redoing it, not because it is non-functional but because it offends the eye. I plan on cutting the kinked part off and using the wood for the inwale, which is shorter.

    Looks like you have a lot of deadwood/skeg to add to that spot, so you may be able to just plane off the biggest hump and cut the rabbet fair. Draw a fairer curve on the keel with a batten to check if you are getting too close to the edge to do this. Don't worry if your bottom curvature in that spot isn't exactly as drawn on the plans, it is probably not a dealbreaker but you might have to redo a mold as well. In traditional Newfoundland boatbuilding the lines were slightly adjusted to the materials available, especially at the stem where naturally curved wood was used.

    If you are choosing to redo it, using a former mentioned above sounds like a good idea, but it also might help to leave the end a couple of feet longer. Steam or not, it is much easier to bend curvature into the middle of a piece than at the bitter end.

  8. #8
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    Default Re: Fixing unfair steam bent keel

    Quote Originally Posted by Schooner36 View Post
    I would steam another one. This early in the game, you want to get the best start possible.
    Good advice here. Also, you might consider making a solid form under the workpiece where it goes into the sharper bend. This will allow the piece to be clamped onto the form to avoid putting all the stress on one portion of the keel.
    Last edited by Jim Ledger; 11-09-2018 at 09:54 AM.

  9. #9
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    Default Re: Fixing unfair steam bent keel

    That is a very easy piece of oak to remove and throw away.
    Much easier than most of them that have boats attached.

  10. #10
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    Default Re: Fixing unfair steam bent keel

    Quote Originally Posted by Schooner36 View Post
    I would steam another one. This early in the game, you want to get the best start possible.
    +1
    If you have much grain runout or any knots, the board won't bend well. The area near the knot bent more because it is weaker than the rest of the board.
    http://forum.woodenboat.com-what-to-look-for-in-white-oak
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  11. #11
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    Default Re: Fixing unfair steam bent keel

    I should clarify a couple things. There is no knot or grain runout at the hard point in the curve. I believe the hard point was caused because I used a form above the molds (i.e. on the bottom of the keel) and the ends of the form (which was of doug fir) crushed from all the pressure. So I don't believe it's an inherent structural weakness in the wood itself, but rather my own mistake.

    Does that change anything to those who suggested redo'ing over some kind of fix?
    Last edited by ptscho; 11-09-2018 at 12:36 PM.

  12. #12
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    Default Re: Fixing unfair steam bent keel

    BOI - Yes, there is a lot of skeg to run along this section. Just planing the rabbet fair seems like an ideal solution to me in terms of not wasting material, as long as I would be left with enough to fasten the garboard. I'll have to check just how much would need removal with some battens.

  13. #13
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    Default Re: Fixing unfair steam bent keel

    Quote Originally Posted by ptscho View Post
    I should clarify a couple things. There is no knot or grain runout at the hard point in the curve. I believe the hard point was caused because I used a form above the molds (i.e. on the bottom of the keel) and the ends of the form (which was of doug fir) crushed from all the pressure. So I don't believe it's an inherent structural weakness in the wood itself, but rather my own mistake.

    Does that change anything to those who suggested redo'ing over some kind of fix?
    No, by using a form under the keel annd ensuring that it is wet enough and steamed for long enough it should bend rounds without problem. As you have left extra length on, bend the extra bit around a slightly tighter radius curve than the keeper part.
    It really is quite difficult to build an ugly wooden boat.

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  14. #14
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    Default Re: Fixing unfair steam bent keel

    Quote Originally Posted by ptscho View Post
    I'm building the Herreshoff Dinghy which has a sprung keel. It's 1 3/8 inches thick white oak, which I steamed and bent over the molds.


    20181108_160416.jpg
    Quote Originally Posted by ptscho View Post
    BOI - Yes, there is a lot of skeg to run along this section. Just planing the rabbet fair seems like an ideal solution to me in terms of not wasting material, as long as I would be left with enough to fasten the garboard. I'll have to check just how much would need removal with some battens.
    There is a fair bit of deadrise there, so by skew nailing you will have plenty to aim at.
    It really is quite difficult to build an ugly wooden boat.

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  15. #15
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    Default Re: Fixing unfair steam bent keel

    Quote Originally Posted by ptscho View Post
    I should clarify a couple things. There is no knot or grain runout at the hard point in the curve. I believe the hard point was caused because I used a form above the molds (i.e. on the bottom of the keel) and the ends of the form (which was of doug fir) crushed from all the pressure. So I don't believe it's an inherent structural weakness in the wood itself, but rather my own mistake.

    Does that change anything to those who suggested redo'ing over some kind of fix?
    It looks like the growth rings loop around the knuckle as if there was a knot in the log next to the plank. Maybe it is just saw marks, but in your picture it does look like the grain is running around something. If you can plane it to a fair curve with enough left to nail, it should be fine. The planks and frames probably provide plenty of strength.

    whatknot.JPG
    Last edited by MN Dave; 11-09-2018 at 09:16 PM.
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  16. #16
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    Default Re: Fixing unfair steam bent keel

    ^...Correcto.

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