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Old 07-28-2013
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Re: Twist

Quote:
Originally Posted by Jeff_H View Post
... instead of flagging your mainsail because you are trying to get the boom to the centerline, you might try really blading out the sail as suggested, minimizing twist, put on gobs of mainsheet, but lowering the traveler so the sail has a flatter angle of attack. You will get a little more drive, less drag and more style points. The other thing in a lot of breeze you can move your jib leads slightly aft and add twist to the genoa. This should reduce heeling and weather helm and may let you use your mainsail more effectively.
Thanks, Jeff. I've got a few dilemmas in there. Let's say "fairly flat seas but with a bit more wind than 'moderate' for the boat". You're suggesting twist in the foresail but not the main. Did I understand that correctly? The books say that usually both sails will have similar twist.

I'm not sure what "blading out" is. But strangely - and I've come across this in several places and confirmed it with some high-level racing sailors - easing the mainsheet, letting the boom rise and freeing the leech (opening, even though the tack and head are on a shorter line to each other) adds twist but flattens the main. This of course means raising the traveller to restore angle of attack with the boom near centre, whereas you say lower it. I can't quite visualize why that flattens, although I can see how it adds twist. But so be it. It also means having a very tight backstay.

That was one of my original points about "twist": one can flatten and twist at the same time (they say!).

Stronger winds need flatter sails (all other things being equal), and twist. Flatter sails allow more of the sail to be closely aligned with the wind, giving more propulsion and less heel. At least, that's what the books say and how I conceptualize it.

Then there's draft position - we haven't got into that yet.

Can you clarify any of the foregoing?

Thank you.

Charles
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