[C320-list] cunningham

[T. Scott Thompson]

Actually the cunningham is for adjusting tension on the luff, not the 
leach.  On my boat the main halyard works just fine for this, and I 
can't imagine why it wouldn't, unless you have lots and lots of 
friction in your mainsail track, in which case you should work on that 
problem instead.  I don't understand or agree with the comment that the 
halyard "isn't effective on the bottom of the sail due to stretch."

Historically the reason for having a cunningham (instead of just using 
the halyard) is related to racing rules.  Under racing rules the top 
and bottom of the sail must stay within marked bands on the mast.  For 
maximum power, you want a sail that comes all the way to the bands in 
both light and heavy wind conditions.  But if it comes to the bands in 
light wind conditions, with not much tension, then it will get pulled 
past the upper band if you tension the halyard when the wind picks up.  
The cunningham solves the dilemma by letting you pull down on the 
bottom of the luff rather than using the halyard to pull upwards.

For a cruising boat there are only two reasons I can think of to use a 
cunningham, but both are legitimate in some circumstances:  (1) The 
sail or halyard are cut and/or rigged such that you can't get enough 
tension on the halyard without damaging something.  This could happen 
if your main has a long luff or if the splice on the halyard shackle is 
chafing on the sheave, for example.  (2)  The cunningham might be 
easier to use, depending on how things are rigged.

By the way, the unusual name comes from the America's Cup skipper who 
invented it.

------------------
T. Scott Thompson
sthompson at toad.net




Quoting Steven Magennis <magenns at yahoo.com>:

> The cunningham is to adjust the tension on the leach (usually on teh
> bottom 1/3), and move the draft forward.  The main halyard does this
> too, but it isn't effective on the bottom of the sail due to stretch.
> 
> Tightening the cunningham (and / or halyard) depowers the sail.
> 
> Streve
> Alchemist #909
> 
> --- John Van Vessem <jvanvessem at sbcglobal.net> wrote:
> 
> > Denny,
> >  
> > I might have missed some of the emails,  what is the purpose of
> the
> > cunningham other than to releave the tension on the boom?
> >  
> > John (Sojourn 645)
> > 
> > rote:
> > Here's a pretty inexpensive Cunningham setup that's on the
> website.
> > You can
> > also get West Marine to sell you a fairly inexpensive block and
> > tackle with
> > lightweight line that works fine.
> > 
> > http://www.catalina320.com/website/cunningham.gif
> > 
> > 
> > 
> > Denny Browne
> > A Cappella #935
> > Redondo Beach, CA
> > 
> > -----Original Message-----
> > From: C320-List-bounces at catalina320.com
> > [mailto:C320-List-bounces at catalina320.com] On Behalf Of Koen
> > Bennebroek
> > Sent: Monday, November 28, 2005 2:00 PM
> > To: C320-List at catalina320.com
> > Subject: [C320-list] cunningham
> > 
> > I was wondering if and how people are using a cunningham in their
> > setup? I
> > noticed on our boat that we have the cunningham cringle in the
> sail,
> > but
> > there is no line with hook. We have a 1995 model with a double
> reef
> > main.
> > 
> > Thanks, Koen
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> 
> Alchemist Associates
> 
> 
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