Some thoughts on Fantail's next sail...

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  • 28 Sep 2016 10:32
    Reply # 4278565 on 4278178
    Anonymous member (Administrator)

    Hi Bryan

    I can see the point in wanting Fantail stay looking like Fantail, both because she as a whole looks so good, but also because I (we, I hope) would hate to upset our dear Annie.

    However, it would be sad if Fantail (or any other junkrigger) had to be locked to a fixed rig design, as Jester has been.  Therefore, for the sake of science (read: curiosity), it would be fun to try her with another rig design.

    For some reason, which I have forgotten now, I drew up a modified Johanna-style rig for Fantail in April.

    Have a look at it:

      

    Since the AR came out so low, none of my 7-panel master sails could be used, so I took a master sail with AR=1.85 and removed the lowest panel, and then crimped the sailplan to right size. I haven’t bothered with drawing sheet 2, 3 and 4 yet, but can do that if you should go for it.

    Twist, camber and fanned sail.
    You are right that will full sail set; the lower panels simply work through conventional camber in the panels in my sails. However, when I am down to 3-4 panels, there is some twist in the fanned top section. It is limited by the lee topping lift. To my eyes it looks a as this adds a bit camber to the low-camber top panels. Whatever the reason, I have found these sails to be very effective to windward with only three panels set. I have tried it in three boats, so far.

    Odyssey versus Dacron.
    As far as I know, the Odyssey is Dacron, or polyester. It is just woven differently.

    Arne

     PS: I suppose that my proposed sailplan should be shifted up to 10-15cm forward of the shown position.

    Last modified: 28 Sep 2016 10:39 | Anonymous member (Administrator)
  • 28 Sep 2016 06:10
    Message # 4278178
    Deleted user
    Circumstances have me stuck one and a half islands away from my boat; Fantail is out of sight but not out of mind. I'm pondering a new sail for her and may have the chance to build one before Christmas. I'd like some opinions on whether or not I'm thinking along the right lines. I won't be changing the mast, which limits the choice of aspect ratio. I'd welcome thoughts/suggestions on the following:

    Planform - the choice seems to boil down to fanned or parallel battens, with fanning gaining a little free camber through twist at the expense of more cloth being required to get the same degree of camber in the sewn cambered panels. I've had a dabble at designing a new fanned sail, and the design doesn't grant much freedom in terms of getting the stagger right. It seems plausible that a cambered H/M sail has marginally more efficient lower panels but loses the chance for 'free' camber through twist in the upper sail... perhaps. But by sticking with a fanned sail, with a truncated top panel,

    • the existing yard can be reused
    • the performance is known to be good
    • Fantail remains a fantail

    Foil shape - I'm pondering bringing the point of maximum camber further aft. Aerodynamic theory says it should be further aft when on starboard tack, but as someone once said, in theory there is no difference between theory and practice; in practice there is. How this would affect port tack is something I couldn't guess at. Arc forward, linear aft of maximum camber.

    Odyssey vs dacron - is the consensus view that Odyssey is okay if it's not subjected to bias tension? This seems to be where Fantail's existing sail has broken down. If the yard is set correctly and the sail 'hangs' from it, is there any reason to shy away from Odyssey?

    Thoughts, anyone?
    Last modified: 28 Sep 2016 07:29 | Deleted user
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