[Rhodes22-list] IMF outhaul setting

[William E. Wickman]

Here's another question.  What effect does increasing the draft of the main
have on pointing ability?  IE., does a flatter main allow you to point
higher?

Bill W.




                                                                           
             "Peter Thorn"                                                 
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             12/11/2005 09:16          [Rhodes22-list] IMF outhaul setting 
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Slim,

We are discussing two outhaul adjustments: a) angle and b) draft.  They are
independent of each other.  Since the IMF is a far better way to depower
than using the only sail controls available on most other small boats
(outhaul, vang, Cunningham, traveler), I think it makes sense to always try
to keep the outhaul angle as bisecting as possible.  This would be the case
whether the draft is very tight or very loose.  As you pointed out, the car
must move forward to keep the angle bisected as the main is furled and the
clew moves forward.  A bisecting angle also evenly tensions the luff and
makes IMF furling go very smoothly.   As most R22 sailors already know,
Stan's unusual traveler does a fantastic job opening the leech (if that is
desired).  So that's another reason to just keep it set bisecting.

As far as draft goes, the deeper the draft the more powerful the sail.  I'm
the type of sailor who wants as much power as possible -- until I'm
overpowered.  Raven sails nicely upwind in 12-15 with her 135 and main set
full.  In those conditions I can hold her to about 15 degrees heel and she
stays on her lines-- it's almost heaven!  With about 10-12" of  outhaul
eased, the helm is light and balanced.  Of course these adjustments are
totally subject to the cut of the sail.  Raven's main (2003 Mack Sails),
has
a slightly higher clew (which makes for flawless IMF furling), no roach and
no vertical batten.

I recall a day last summer in lighter air with the low clew 175 and the
main
set more flat.  With this setup having so much power in the headsail and
the
main set flat there was definitely some lee helm.  Under those conditions,
I
think the main should be as full as possible too.  Stan recently invented
the new vertical batten main, a bigger sail with more power to balance the
175 -- perhaps the ideal rig for light air.

<So my question is what's the distance between clew and spar and under what
conditions?>

I think this depends on the cut of your mainsail.  First, furl main, then
set outhaul car to bisect, then set draft.   You are furling to depower, so
I guess you would want the outhaul pretty tight.  The distance between the
clew and spar would depend more on how high the main clew is and really
doesn't matter than much.  Raven's high clew main, 40% furled, angle
bisecting, traveler down all the way leeward for tight leech-- I think
there's more than 12" of outline line, maybe more.  The significant factors
are bisecting and draft tension.

All this detail stuff keeps sailing interesting, doesn't it?

PT




----- Original Message -----
From: "Slim" <salm at mn.rr.com>
To: "Rhodes22-list" <rhodes22-list at rhodes22.org>
Sent: Sunday, December 11, 2005 2:38 AM
Subject: Re: [Rhodes22-list] IMF outhaul setting ver 2 for Ed.pdf


> Peter,
>
> I'm so glad someone finally brought this up.  OK, I understand this
> geometry--it's the same as adjusting the jib sheet cars so the imaginary
> line bisects the luff.  I get that.  But in practice, the clew of my main
is
> never more than an inch or so from the spar itself under full sail.  If I
> reef in for higher winds, I position the car forward right up close to
the
> clew.   And for higher winds, you want the outhaul tight to flatten the
> sail, right?  So are you talking about very light air when you ease the
> outhaul?  Still, when I do that, I only ease it a couple inches.  Maybe I
> should be easing it a lot more?   And the follow-up
> question:  if the clew is within a couple inches of the spar, does the
angle
> make any difference?
>
> Slim
>
> On 12/10/05 9:44 PM, "Peter Thorn" <pthorn at nc.rr.com> wrote:
>
> > Ed,
> >
> > How's this.
> > Name: IMF outhaul setting ver 2 for Ed.pdf Type: application/pdf Size:
84818
> > bytes Desc: not available
> > Url:
> >
http://www.rhodes22.org/pipermail/rhodes22-list/attch/200512/10/IMFouthaulsett

> > ingver2forEd.pdf
> >
> > __________________________________________________
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>
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