Received: from hplms26.hpl.hp.com by jr.hpl.hp.com with ESMTP (1.37.109.18/15.5+ECS 3.3+HPL1.1) id AA164132758; Fri, 28 Feb 1997 18:19:18 -0800 Return-Path: <bo3b@mail.apple.com-DeleteThis> Received: from mail-out1.apple.com by hplms26.hpl.hp.com with ESMTP (1.37.109.16/15.5+ECS 3.3+HPL1.1S) id AA096772757; Fri, 28 Feb 1997 18:19:17 -0800 Received: from scv1.apple.com (A17-128-100-119.apple.com [17.128.100.119]) by mail-out1.apple.com (8.8.5/8.8.5) with ESMTP id SAA16490 for <wind_talk@jr.hpl.hp.com-DeleteThis>; Fri, 28 Feb 1997 18:14:24 -0800 Received: from [17.203.21.140] ([17.203.21.140]) by scv1.apple.com (8.8.5/8.8.4) with SMTP id SAA15412 for <wind_talk@jr.hpl.hp.com-DeleteThis>; Fri, 28 Feb 1997 18:16:01 -0800 Message-Id: <199703010216.SAA15412@scv1.apple.com-DeleteThis> Subject: Flat sails Date: Fri, 28 Feb 97 18:16:58 -0800 X-Sender: bo3b@mail.apple.com-DeleteThis X-Mailer: Claris Emailer 1.1 From: <bo3b@apple.com-DeleteThis> To: <wind_talk@jr.hpl.hp.com-DeleteThis> Content-Type: text/plain; charset="US-ASCII"
>those days. I got completely hammered on the 4.3, even after I made the
>sail
>so flat that
>it resembled a sheet of plywood.
...
>3.3 was way too big. Came back on shore and flattened it to the max. Still
On the subject of flat sails, since I see it pop up here a fair amount:
For what it's worth, when we went to Maui to windsurf, we had a couple of
classes with Cort Larned. We asked him specifically about the flattened
sail idea, and he said it was one of the worst things that you can do if
you are overpowered.
The reason is that if you take all the curve out of the sail, the sail is
no longer an airfoil, and thus it genuinely is a board. Either side can
take the wind, which makes it twitchy, as the airflow flips from side to
side. This makes sailing much harder, since the airfoil is totally
unstable.
His recommendation for overpowered is to partly flatten the sail to
reduce the power, but still keep a curve. You don't want the full bodied
curve, since you don't need that power, but you don't want it flat either.
Then, the even better way to reduce power is to put on more downhaul, so
the leech gets looser, even down to the boom, spilling more wind,
handling stronger gusts, but keeping an airfoil.
With that minimal power setting, you just sheet out to handle the extra
power. If the sail is too flat, you can't sheet out and maintain
control. If you still have some curve, it won't be twitchy, it'll just
have less power as you dump most of the wind.
Cort's 2c.
I haven't tried it yet, but if anyone does, I'd be curious to know how it
works. I have tried the fully flat, and didn't care for it, which is why
we asked in the first place.
-- Bo3b.
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