OK, here we go. There is true wind and there is apparent wind. Apparent wind is the
wind you feel if there is no wind and you're
on a bike and you start moving forward. It feels like there is wind, right?
Sailboats use wind and forward motion to work. Proper
sail trim is extremely important to achieve maximum efficiency from any given boat.
You are manipulating your "wing/sail" with many
different lines. OK. A close hauled (point of sail into the wind) mono hull sail
boat can pretty much only go what is called hull
speed. Now, you crack off the sails a little, head off the wind a bit and you start
generating more of your own wind by gaining
more speed. This is the true wind and your forward motion combined, hence more
apparent wind and hence more speed. Anytime you
sail past where the apparent wind is on your beam you throw up your spinnaker (big
pretty sail) and you go even faster. Your sails
are still working as a wing and you are being "lifted". That is until you are running
down wind and then you only go as fast as the
true wind is blowing. You cease getting lifted by your sails anymore. Your are
"running before the wind". It doesn't matter
what kind of a boat you are on either unless you are in a situation where you have a
planing hull or there are waves and you
break-loose and start surfing. ULDB's (ultralight displacement boats) which became
extremely popular in the 70's can surf the ocean
& bay waves very well. Once down wind its only as fast as the wind is blowing for
most boats. Its a pretty scary point of sail in
a blow too. In sailboat racing, un-wanted jibes while running down wind result in
what is commonly know as the "death roll" and you
can be pinned on your side if you "round down".
OK, in the medium of the ocean there is a lot of drag from the water. On land with
only three wheels on the ground there's a lot
less friction. On ice its even less. That is why extreme speeds can be achieved in a
realitivly light wind. Its can pretty much
be summed up by saying " the faster you go, the faster you go ".
OK, so now if you want to sell all of your gliders and buy a sailboat and want to live
on the wild side, buy a mutli-hulled sailboat
and go real fast. Be prepared to get wet though.
I am sure there is a much more scientific explanation and I'm looking forward to the
many theories forthcoming on this glider
exchange.
Cliff Lindgren
Brett Jaffee wrote:
> Well, as others have pointed out, there are sail powered vehicles that can
> go faster then the actual wind (I'm still not quite sure how that works,
> but apparently it does). As for flat areas with lots of wind, you've got
> places like the Bonneville Salt Flats in Utah, or even Rogers Dry Lake near
> Edwards AFB in California.
>
> At 10:25 PM 01/04/2000 -0800, Tracy R Reed wrote:
> >On Tue, Jan 04, 2000 at 04:45:34PM -0800, Brett Jaffee wrote:
> >> stab. Supposedly, it could go 120mph.
> >
> >In a 120mph wind? Where do they find such wind with flat land to race on that
> >isn't covered in dunes?
> >
> >--
> >Tracy Reed http://www.ultraviolet.org
> >The idea that Bill Gates has appeared like a knight in shining armour to
> >lead all customers out of a mire of technological chaos neatly ignores the
> >fact that it was he who, by peddling second-rate technology, led them into
> >it in the first place. - Douglas Adams in Guardian, 25-Aug-95
> >
> >
> ____________________________________________________________________________
> Brett Jaffee: [EMAIL PROTECTED]
>
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