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Thread: Bi-Rig Cats

  1. #21
    Join Date
    Nov 2008
    Location
    Idaho, USA
    Posts
    189

    Default Re: Bi-Rig Cats

    Quote Originally Posted by BigCat View Post

    Attached is a drawing my my latest design, one well suited to bringing along family and friends.
    Attachment 6581
    Hey BigCat,
    Ive noticed that Tystie (the ketch rigged monohull using a type of Junk Winsail), has had some issues regarding keeping the correct shape in his sails. Do you have any thought as to why your design may or may not have similar problems?
    I seem to recall your earlier renderings having the leech of the two sided part of the sail curved to follow the luff. Now, it appears to be a straight line. Is this a change in design? If so why? Have you done any modeling with your design?
    I'm seriously interested in seeing a well designed, working version of something similar to what you have drawn.
    Thanks!

  2. #22
    Join Date
    Oct 2008
    Location
    near Seattle
    Posts
    1,116

    Default Re: Bi-Rig Cats

    Quote Originally Posted by solarbri View Post
    Hey BigCat,
    Ive noticed that Tystie (the ketch rigged monohull using a type of Junk Winsail), has had some issues regarding keeping the correct shape in his sails. Do you have any thought as to why your design may or may not have similar problems?
    I seem to recall your earlier renderings having the leech of the two sided part of the sail curved to follow the luff. Now, it appears to be a straight line. Is this a change in design? If so why? Have you done any modeling with your design?
    I'm seriously interested in seeing a well designed, working version of something similar to what you have drawn.
    Thanks!
    Hi, Solarbri - I'm not sure what you mean about the leech following the luff. I have made two versions, one with a straight luff and one with a curved luff. In both, the leech is curved.

    A straight luff lends itself to easy building and sail making because the foil part of the battens can be identical. A curved luff and leech means that foil part of the battens all have to be different, and the sail becomes more complex to cut. The curved leech and luff looks cool, and tapering the sail at both the top and bottom should reduce power losses caused by vortex formation. Tapering the bottom does raise the center of effort a bit, however.

    Tystie is in British Columbia the last I heard, and David has made another wingsail rig. The new wingsail rig has already been modified because David had some breakage, and he has another issue, which is that his foil (wishbone) part of his battens were attached rather loosely to the sail. http://www.junkrigassociation.org/te.../3038372?tpg=3

    I would be inclined to make the foil portion of the battens out of foam cored fiberglass, with the joint parts made out of carbon fiber. I would also hold them in place with battens on the outside of the sail, held to the battens with screws through the sail. The screw holes can be fused with a soldering iron. I would use a Clark-Y (that is the curve that is the top half of the Clark Y foil,) section for the foil.

    https://www.youtube.com/watch?v=H1cEFP_H4Rk seems to set nicely, but the lack of the junk type sheet going up the leech means that there is more stress on the mast.
    Currently concentrating on http://earthnurture.com .

  3. #23

    Default Re: Bi-Rig Cats

    Re:Big rig cat
    Big rig cat to be built to a high standard in epoxy E-Glass composites by Two Oceans Marine with freestanding custom carbon wing masts. The bi-plane rig was chosen for its easy handling and efficiency and matched to a hull shape optimised for good performance, carrying capacity and interior volume. Optional sloop rig also available. In addition to the owners’ accommodation which is in the starboard hull and includes a workbench there is space for two guest cabins in the port hull. The light and airy New England style interior adds to the overall feeling of space and comfort.

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