Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: sailing upwind? Some NG Comments



At 14:43 12/31/99 -0800, Bill Beaty wrote:

... suppose we build a machine that contains a pair of sailboats
with sliding connection to a long rod......
..."morph" this into a single simpler device...

William J. Beaty

I wrote some boating newsgroups to mention this interesting thread
running on phy-l, and asking for guidance.
I received several interesting responses, and I will quote two, one
of which describes Bill's model persuasively.

----Forwarded----
Newsgroups: rec.boats.building,rec.boats.cruising,rec.boats

From: wshill@nospam.world.std.com (Wayne S. Hill)
Subject: Re: Sailing into the Teeth of the Wind.

Date: Sat, 1 Jan 2000 16:14:15 GMT
...
There have been several boats that can "sail" directly into the
wind by using a wind generator to drive a submerged propeller.
Marcus is exactly right in his analogy of prop blade and windmill
blade to keel and sail (respectively). Consider 2 identical
conventional sailboats on opposite tacks: their center of mass
goes directly to windward. If you have any imagination at all,
you can conceive a sliding platform that connects these 2 boats,
which goes directly to windward. Now generalize this design, so
that the sails of the 2 boats become blades of a wind generator,
and the keels of the 2 boats become a propeller, and you see
that it can be done and doesn't violate the 2nd law.

-Wayne
-----------------------------------------------------------------
Dr. Wayne S. Hill (Penn alumnus) wshill@world.std.com
Foster-Miller, Inc. 781-684-4228
====================================================


----Forwarded----

From: jaxashby@aol.com (JAXAshby)
Newsgroups: rec.boats.cruising
Subject: Re: Sailing into the Teeth of the Wind.

brian whatcott writes:

How close to the wind can a boat sail?
...
Oh, boy. Here we go again. Someone says he heard of a sailboat with a
wildmill propellor driving an underwater propellor pushing the sailboat --
without any other source or power -- directly into the wind.
Someone screams "Impossible!!" (I know my physics/sailing/whatever).
Someone else smugs back "Well, here's a picture of such a boat".
#2 (and #'s 4/6/8/10/12/14) shout back "You're a dummy.
That picture is a fraud!! (I know my physics/sailing/whatever).
#3 saying "Well someone has a patent on such a
boat". #5 says "I hold the patent". #'s 2N shout "FRAUD!!
You're ALL dummies!!" (I know my physics/sailing/whatever).
And so it goes for about four or five weeks.

Brian, save yourself some time. Either accept that such boats
do exist now, have existed for more than 20 or 30 years, that
about the time the first such boat arrived physicists argued whether
it was even possible and came to the conclusion that it is possible
(and indeed is just another variation on the lawn spinkler under
water "problem"), there is a UK patent on such a boat,
and Scientific Amercian has written up such a boat.
Or ... you can do a search on files for the last year or so,
pull 'em and start reading.
------------------------------------------------------------------------


Hope you enjoyed this as much as I did.

Sincerely

Brian Whatcott




brian whatcott <inet@intellisys.net>
Altus OK