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Thread: Modifications to Elfyn

  1. #1
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    Default Modifications to Elfyn

    As I work on Oughtred's Elfyn I was asked about modifying the plans for a pivot up dagger board and rudder. Plans show one piece for each. Solo sailor with limited experience worried about managing the two by himself as he closes in on shore. Anyone done this and have some drawings?

  2. #2
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    Default Re: Modifications to Elfyn

    I highly support the idea of a kick up rudder but do not ruin the boat with a pivoting centerboard, please. A long slot creates a lot of drag to slow down the boat and effect the good rowing qualities of the boat.
    Last edited by Clinton B Chase; 06-28-2022 at 07:14 AM.
    Clinton B. Chase
    Portland, Maine

    http://tinyurl.com/myboats

  3. #3
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    Default Re: Modifications to Elfyn

    Quote Originally Posted by Clinton B Chase View Post
    I highly support the idea of a kick up rudder but do not ruin the boat with a pivoting centerboard, please. A long slot creates a lot of drag to slow down the boat and effect the good rowing qualities of the boat.
    Not to mention the structural issues. You would need to approach the designer to redesign the keel and cb case bed logs.
    It really is quite difficult to build an ugly wooden boat.

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  4. #4
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    Default Re: Modifications to Elfyn

    Customer had inquiries as to could it be done as I believe he has seen it on other Oughtred designs or YouTube videos? Alas, the internet and too much information. I did send an inquiry to Oughtred Boats but had same thoughts on the centerboard box. Would need to be very long for that board to pivot into. I really like the design of the rudder as well. I prefer to stick to the plans, so just some thoughts about why it is not a good idea.

  5. #5
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    Default Re: Modifications to Elfyn

    It isn't hard to add a slot gasket to any length of slot and the girder effect of the longer case sides might be beneficial.There isn't any lateral load behind the lowered board of much significance.

  6. #6
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    Default Re: Modifications to Elfyn

    The displacement distributed over a narrower waterline gives the bottom of Elf/ Elfyn more V. As shown, if I remember, the keel/ keelson is accordingly narrow, and Iain shows a daggerboard placement to the side through the garboard abutting the keelson. I guess a simple metal plate would be narrower and might fit through the narrow keelson though...

    It might be best to stick to plan A given this shape/ structural limitation.

    I've read a sailing review of and Elf/ Elfyn that apparently sails OK without a daggerboard, I guess the V gives it some grip.

    You really have to be sat in the middle of these boats, sit aft and the skeg immerses and it won't turn. So he should/ will be sat closeish to the daggerboard in the middle of the boat.

    I can see the advantages of a centerboard, but a daggerboard is a quicker lighter structure to build, and the foil is always angled to the waterflow properly and works better at partial immersion. Beside the turbulence, which could be avoided with a slot gasket probably, I guess the longer case might infere with the frames - isn't there two in the boat if I remember, or floors.





    You wouldn't die in a ball of lames, but it would be a shame to saw that laminated frame in half you can see behind the daggerboard if you put in a centerboard. It takes the oarlock stresses.

    I'd also just look at how wide the foil is. Does it fit under the thwart without adjustment? Solo, I'd want the thwart (the rowers weight) positioned over the center of buoyancy in the middle and not have to move that or raise it, as its a rower of ability.

    More work for you, will mean more cost for him.

    I might do a lifting rudder though. The rudder gear from classic marine costs 250-300 though to be fair there's 6 pieces of cast bronze. That's hard to swallow.

    Is he a sailer or rower? A sailer will likely like a semi balanced high aspect rudder, a rower will likely prefer a low aspect unbalanced rudder that keeps itself straight and the boat going straight without too much input while rowing.

    Generally it's best to stick to the plan with Iain's boats. He's built and used them and knows what's best from experience, even if it's not imemdiately apparent. I think the apect ratio of the rudder changes between the high and low position as drawn by Iain. If you look at it, in the high position for rowing, as it 'goes around the bend' of the aft stem, the aspect ration will reduce a bit.



    This stuff Iain thinks about but doesn't explain till you see it.

    If your client insists you should look at the slightly more sail orientated Whilly Tern or Ness Boat/ Tirrik for how the centerboard case is shaped and a picture of the rudder will show you how Iain likes it. The aft stem curve will give you the front face of the rudder head to match...

    If you want to avoid a centerboard pin, if you look at how Vivier does the Ilur's foil/ case you can see how that works. Its simple and clever and avoids a through pin that can be a leak point.
    Last edited by Edward Pearson; 06-29-2022 at 07:18 AM.

  7. #7
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    Default Re: Modifications to Elfyn

    Yes the aft frame would have to be cut for a longer box. The hull is already planked and rolled with frames in place, so not an option to look at another design. Took him two years to decide on this one and is retirement dream. He is not a sailor so has no experience on what is best for him.

  8. #8
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    Default Re: Modifications to Elfyn

    One thing you can do with a daggerboard box is have a short dummy daggerboard that fills the case and slot just flush with the bottom to avoid any drag from the opening.

  9. #9
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    Default Re: Modifications to Elfyn

    I have a Whilly Tern and the slighty offset swinging board is very useful in our shallow coast. Rudder is also kick up.
    I cut the slot after the hull was fully planked and then built the box, as to the plans.

    A friend has built an Elfyn, but without a board, as he expects to mostly row, sail if the wind is aft.

  10. #10
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    Default Re: Modifications to Elfyn

    These sail quite well without any hole in the bottom at all atall.
    P1060430.jpg
    straps 011.jpg
    GUNTER LUG.jpg
    It really is quite difficult to build an ugly wooden boat.

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