Polars are the fare of armchair sailors. Anyone who has actually sailed
downwind against a faster boat when said faster boat was jybing downwind
and getting further and further behind realizes that in real life sailing dead
downwind is faster for a keelboat that is restrained by a theoretical hull
speed. The bottom line is 15 degrees does not make a boat go all that
much faster because sail area is effectively reduced. The main, blankets
the jib or genny where running dead downwind leaves both the genny
and mail totally exposed to the wind.

Show me an America's cup where on a dead downwind leg boats are
jybing downwind and coming out ahead and I might give a little credence
to your nonsense. The races I've watched show these cutting edge vessels
running straight downwind and only turning slightly now and then to
keep boats upwind of them from blocking their wind.

Racing cats and tris, now that's a different story. Given strong winds these
craft are close hauled or close reaching on all legs of a race course because
they do, indeed, have the capability to tack downwind and complete the
course faster.



"Jeff Morris" jeffmo@NoSpam-sv-lokiDOTcom wrote in message ...
Hey Neal - you're beginning to sound like Jax. What's next - are you going to claim
Einstein proved you can't navigate in the fog?

I wouldn't expect an English major to remember any high school trigonometry (assuming you
ever passed the course) but it only takes a simple calculation to show that you only go 4%
further when you run at 165 degrees instead of 180. You only have to go a little faster
to make this up. In fact, you only have to go 15% faster to make up the difference in
running at 150 degrees. Thus, you can jibe through 60 degrees true and only need a 15%
increase to make it worth while.

Here's a polar for a Catalina 36. I don't think anyone would call this a planing boat,
especially in light air:

http://albertson.sytes.net/~chris/C3...6Polars_al.gif

The chart clearly shows that you can go 25% faster in light air by jibing downwind in
light air.

Are you claiming that all the Polar Diagrams are false?


"Simple Simon" wrote in message
...
A displacement boat that does not plane will always
arrive at a destination in less time by running directly
downwind to it. Gybing downwind does result in slightly
faster speed through the water in lighter winds but the
extra distance traveled results in a longer time to arrive
at the destination. This is just plain common sense and
physics at work. Anyone who claims something different
is living in Lala Land. You're beginning to sound as
stupid and ignorant as Jeff Morris.


wrote in message
...
On Thu, 17 Jul 2003 18:46:06 -0400, "Simple Simon" wrote:

That is incorrect information for any displacement monohull where
it is always faster to run straight downwind.

Baloney! An under canvassed tank like yours or Bobadil's might benefit quite a
bit from gibeing back and forth rather than going directly downwind. I do better
going strait downwind, because I can put up the mylar main and 170 genoa, or a
spinnaker and take advantage.

BB