junk lateen yawl ?

Discussion in 'Sailboats' started by Timothy, Apr 22, 2008.

  1. sharpii2
    Joined: May 2004
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    sharpii2 Senior Member

    There are two potential problems I see here.

    1.) You are counting on the yard to not only support the weight and compression of the whole sail, but are depending on it to hold it reasonably close to the mast. As the sail fills, it is going bow out along its height. The more it does this, the more it's going to bag. And the more it bags, the less lift and more drag it's going to create, causing it to bag even more. This will put tremendous tension on your halyard, not to mention bending compression on the mast.

    2.) You got a little greedy on how much you want the yard to extend above the mast. The fulcrum point of the yard seems unreasonably close to its front end. This gives it little leverage, putting tremendous tension on the luff, not to mention even more tension on the halyard, which will be sure to contribute to the ills mentioned above.

    I would suggest:

    1.) putting a spacer on each of the battens to hold them both to and away from the mast (greatly mitigating or even eliminating my first objection), and

    2.) moving the pivot point of the yard aft, to at least 1/3 its length.
     
  2. Cutta
    Joined: Oct 2009
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    Cutta Junior Member

    I was thinking that the hull had aspects of LFH; namely a slender shape, long run, graceful curving sheer and a tendency to tumblehome midships. I started studying modifications of LFH lines after seeing this design. The long raking shoal draft keel is typical of N.I., but it would appear a bit narrower in the transom than his designs.
    Cutta
     
  3. NoEyeDeer
    Joined: Jun 2010
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    NoEyeDeer Senior Member

    Why? The rig is completely impractical. It looks good in the rendering, but anything can look good in a rendering.
     
  4. gilberj
    Joined: Oct 2010
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    gilberj Junior Member

    I like it, though I think the peculiarities will make this a very expensive option...
     

  5. Timothy
    Joined: Oct 2004
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    Location: canada

    Timothy Senior Member

    .I would like to say that when I first conceived the idea for this rig, I had just seen Gary Hoyt’s concept for his offset rig. My boat is a Freedom 40, the hull designed by Halsey Herreshoff and inspired by a design of his grandfather “Nat” but rigged by Hoyt with his” Freedom Rig”, two identical freestanding masts with wishbone booms and wrap around sails. I had always thought that the aft cabin looked somewhat truncated so I digitally modeled it with a three foot extension of the stern. The original Freedom 40 has a transom hung rudder and a boom kin so the extension does not add to the overall length of the boat but puts the rudder under the hull. I knew that the later Freedom forty four was made this way but without the center cockpit or galleon stern. I wanted to clear the cockpit and had always admired Nigel Iren’s “Romilly”and “Roxane” so I decided to see what would happen if I were to rig the boat as a yawl with two Hoyt offset rigs . I didn’t like the idea of having the yards fixed to the top of the masts and I liked the look of Roxane’s standing lug so I angled the yard and secured it to the mast on a sliding arm. I had also recently read of Rob Denny’s proposal for a telescoping mast, so I thought why not give that a go as well.
    I made a small physical model and it seemed to work well but when I actually began to do some number crunching I came to the conclusion that even if I could get it right that it would be too expensive to build and probably not any more efficient than a standing lug yawl or for that matter a yawl with James Wharram style soft wing.sails .
     
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