"mister b" wrote

in these times, he'll drop his main and roll the jib way in well below
100%...his boat still moves well to windward...so I'm confused about the
claims of poor shape/performance when rolled way in...he says it's BS and
has the empirical evidence at hand...I guess it depends on context.


Is he just moving well to windward or is he beating to reach an objective to
windward? A jib rolled way down (I think you meant 50%) will still drive
the boat to windward but it won't point very well or be as fast as with
smaller sail not rolled down as much. I could get my boat to make steady
progress to windward with the old 150% genoa rolled down to nearly that
amount but it was pretty discouraging to look at the GPS track on a long
beat.

The thing that got me thinking about the smaller, compromize Genoa I had
built was noticing how much faster the boat was to windward with the small
working jib in fresh breezes. The performance difference between the 150%
and the working jib (about a 110% overlap) even in light air and on reaches
was much less than the difference in sail area would indicate.

--
Roger Long

On 2008-08-09 21:06:04 -0400, "Roger Long" said:

The performance difference between the 150%
and the working jib (about a 110% overlap) even in light air and on reaches
was much less than the difference in sail area would indicate.

Upwind, the difference is pretty much the difference in length about a
foot or so behind the luff, where the power comes from. There's some
benefit from less drag in the smaller sail, too.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/

"Jere Lull" wrote

Upwind, the difference is pretty much the difference in length about a
foot or so behind the luff, where the power comes from. There's some
benefit from less drag in the smaller sail, too.


Exactly. My old Genoa, reefed down to the area the boat could carry in fresh
conditions, had less leading edge than the working jib. I now have just a
bit more area than the old working jib with full length leading edge and
more leading edge when reefed to the old working jib size. The overlap area
is really only effective reaching and, if you want the 150% area for light
air, better to put it in an asym.

--
Roger Long

On Sat, 9 Aug 2008 21:06:04 -0400, in message

"Roger Long" wrote:

The thing that got me thinking about the smaller, compromize Genoa I had
built was noticing how much faster the boat was to windward with the small
working jib in fresh breezes. The performance difference between the 150%
and the working jib (about a 110% overlap) even in light air and on reaches
was much less than the difference in sail area would indicate.

I don't know about anybody else, but my racing bias tends towards too
much sail. The last couple of weeks we went cruising with the cocktail
jib (about 115% with a really high clew) on the furler. As best I
could tell, the speed penalty was 10 or 15 percent and 3 or 5 degrees
of point. Based on observing the boats around us, most cruisers don't
seem to care about that.

The really big plus is that you can carry a sail like that well up to
about 25 knots to weather without having to roll it in, and you can do
what we call "cruising tacks" -- slow turns with enough time luffing
to trim without much power grinding.

Ryk

Ryk
My headsail size is determined by the best VMG (not speed) I can get.
Many times a too big sail plan will have too much leeward slip when
going 'up' ... drops VMG catastrophically. Its my belief that the
high end race folks match the SA to the optimum VMG for best
performance upwind and thats why it seems that over the years the
headsails are getting smaller and smaller in LP. Such is also
'easier on the rig' as a BIG LP heasail needs lots of winch pressure
which ultimately reacts to sag off the headstay to leeward, ...
requires more backstay tension, etc. etc. etc. etc. etc.
:-)

On Wed, 13 Aug 2008 10:02:16 -0700 (PDT), in message

RichH wrote:

Ryk
My headsail size is determined by the best VMG (not speed) I can get.
Many times a too big sail plan will have too much leeward slip when
going 'up' ... drops VMG catastrophically. Its my belief that the
high end race folks match the SA to the optimum VMG for best
performance upwind and thats why it seems that over the years the
headsails are getting smaller and smaller in LP.

The high end race folks go through endless headsail changes to
optimize VMG. Rigs have moved towards smaller headsails and bigger
mains to make it easier to "change gears", as far as I can tell.

Such is also
'easier on the rig' as a BIG LP heasail needs lots of winch pressure
which ultimately reacts to sag off the headstay to leeward, ...
requires more backstay tension, etc. etc. etc. etc. etc.

Easier on the crew as well. My point was that a cruising sail plan can
include a small jib with no practical loss of performance unless
things go really light.

Ryk

:-)