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  1. #31
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    Quote Originally Posted by dom View Post
    OK a smidge perhaps; but mast bend, then batten tension, then outhaul become the dominant parameters. Which makes me wonder how suitable masthead rigs are to fully-battened sails, in particular when hard on the wind.
    On my boat with a fully battened main halyard tension is pretty much all I have to play with once the sail is up. The position of maximum draft can be changed more than just a smidge. My mast is almost totally rigid and cannot have further bend applied from sail controls, the outhaul cannot be changed when the sail is loaded, no Cunningham, and batten tension is not changed all season. Full battens allow a large roach though as I have no backstay.

    Sailing performance on a Dragonfly comes more from brute force and ignorance than any twiddly sail shape tweaking.

    'ere it is...

    Last edited by AngusMcDoon; 23-12-14 at 23:06.
    Andersen 22. The best winch never made.
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  2. #32
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    Fully batterned (or at least mostly - like TK) is absolutely what I'd specify for cruising. Gives a great sail shape without much effort, maximises area, helps keep the sail tamed and not flogging itself to bits when motor sailing etc.

    The reason racers don't use them is largely that it is very difficult to depower them. Not a problem on a cruising boat, you just tuck a reef in, but you don't want to do that racing, as you're about to turn the corner and go downwind.

    There is a trend now amongst the very high end boats to go for "square top" mains - like these.
    http://www.mcconaghyboats.com/mc38-specifications.html

    But even then, only the top couple of battens are full.
    You never know, I might be right!

  3. #33
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    Quote Originally Posted by flaming View Post
    There is a trend now amongst the very high end boats to go for "square top" mains - like these.
    http://www.mcconaghyboats.com/mc38-specifications.html
    Are they backstay-less using some form of rig like the B&R?
    Andersen 22. The best winch never made.
    miniwinwm.wixsite.com/miniwinwm

  4. #34
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    Quote Originally Posted by AngusMcDoon View Post
    Are they backstay-less using some form of rig like the B&R?
    No, twin backstays going to the aft most winches. Mostly a tuning aid I'm told though.
    You never know, I might be right!

  5. #35
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    Quote Originally Posted by AngusMcDoon View Post
    The position of maximum draft can be changed more than just a smidge. My mast is almost totally rigid and cannot have further bend applied from sail controls

    Sailing performance comes more from brute force and ignorance than any twiddly sail shape tweaking
    Aha, I see you sail a Dragonfly, I've sailed a couple of those before and once with Jens Quorning in Denmark, I think it was a 920 Extreme. IIRC the central backstay is replaced by de facto running backstays on each of the two floats, which as you say cannot be over tensioned for structural reasons. I do remember there's a logic behind the circular mast section but forget what it's based on.

    Nice sail, but for the life of me I can't see how you can change the shape of a sail much with so many battens using halyard tension alone, but I'm happy to take your word for it.

    As for the performance thing, let's agree to differ; I was always taught it comes from brute force and "finesse", but each to their own.

  6. #36
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    Quote Originally Posted by dom View Post
    I do remember there's a logic behind the circular mast section but forget what it's based on.
    It's a lot cheaper to make and more robust than a foil section, as simple as that.

    Quote Originally Posted by dom View Post
    I can't see how you can change the shape of a sail much with so many battens using halyard tension alone.
    Lots of it. 2-1 Dyneema halyard, rigid almost straight mast, low friction cars all mean that the tension can be cranked up and effective.

    Quote Originally Posted by dom View Post
    As for the performance thing, let's agree to differ; I was always taught it comes from brute force and "finesse", but each to their own.
    What I mean is that my boat has minimal sail tweaking controls, but a high sail area to displacement ratio - so it's brute force rather than finesse that makes my boat go. I realize that it's different on other boats with lots of bits of string and crew to pull them. I've edited my post above to make that clear.
    Last edited by AngusMcDoon; 23-12-14 at 23:08.
    Andersen 22. The best winch never made.
    miniwinwm.wixsite.com/miniwinwm

  7. #37
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    Quote Originally Posted by AngusMcDoon View Post

    Lots of it. 2-1 Dyneema halyard, rigid almost straight mast, low friction cars all mean that the tension can be cranked up and effective.
    I seem to recall that the mast section and taper was inspired by something, but for the life of me can't remember what.

    Re sail shape, I'm familiar with 2:1 dyneema halyard systems and have the same on my boat. But I cant get my head around how off-axis forces on the mainsail could impart a significant change in the shape of so many battens, unless they're exceptionally light. I'd be genuinely interested to see before and after halyard tension photos.

  8. #38
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    These are the battens...

    http://www.fiberfoam.net/sailbattens/

    sail trim pics will have to wait until my mast is back up.
    Andersen 22. The best winch never made.
    miniwinwm.wixsite.com/miniwinwm

  9. #39
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    Quote Originally Posted by flaming View Post
    No, twin backstays going to the aft most winches. Mostly a tuning aid I'm told though.
    It's a brave man who puts that supposition to the test on a downwind leg.

  10. #40
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    Quote Originally Posted by AngusMcDoon View Post
    sail trim pics will have to wait until my mast is back up.
    Fair enough. BTW for cruising that's a nice main, very nice

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