Faster upwind tacking by taking turns towing?

xarax · Apr 15, 2005

Yes, such a "double-sailboat" can sail to windward indeed.

Incidentally, I happen to arrive at the same conclusions as yours, even for the case of a sailplane. However, the "theoretical" reasoning is useless - and would not convince anybody in this forum, that is for sure - unless you bring along some experimental evidence. A simple advice: Proceed building a small radio-controlled model. Try to exploit the momentum of the hull A (windward-sailing) around the hull B (dragging the A hull with the help of its keel) as much as possible.

globaldude · Apr 15, 2005

Ahh, well put Steve. Here in New Zealand, we have highly paid teams employed by our government, namely for the making of regulations relating to transportation , and again, as to the best means of squeezing tax from us non " mathematicians ".
We are also known as great sailors.
I feel quite confident that , should mr Hall wish to emigrate, our goverment would welcome him with open cheque book.
He may even be able to help " team New Zealands" latest bid for the America's cup - if the last one was anything to go by !.

brian eiland · Jun 24, 2005

How Sails Work

h.t.hall said:

...I think I can safely claim to be more ignorant about sailing than almost anyone else on this forum: I've actually never set foot on a sailboat. (And this after having lived both in the San Francisco Bay Area and on the shores of Lake Geneva, quel dommage!) As a result, anything I say is likely to be complete nonsense in terms of practical sailing, and it may be difficult to even understand what nonsense I intend since I'm not familiar with the correct terminology.

I'm a mathematician (here's where most of you stop reading), and just for fun the past couple of days I've been thinking a bit about what makes it possible to sail against the wind. In an extremely simplified mathematical model, tacking is possible because the force vector of the wind is projected three times. (To project a vector means to separate out the useful part of it from the part that's just pushing sideways.) First the wind vector is projected in a direction perpendicular to the sail, then the force from the sail to the boat is projected parallel to the keel, and then the fact of constantly switching tacks amounts to a third projection: when the keel isn't pointed in the direction you want to go, your motion has forward and sideways components, and only the forward component is useful....
Click to expand...

I just want to refer you to a couple of articles I think might help you in understanding the subject a bit better....and that have some vector presentations:
1) How Sails Work by Paul Bogataj
http://www.northsailsod.com/articles/article6.html

2) Arvel Gentry's work
http://www.arvelgentry.com/

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Faster upwind tacking by taking turns towing?

xarax Previous Member

globaldude court jester

brian eiland Senior Member

Some questions on polars and upwind/downwind performance

Upwind daggerboard installation on a production displacement sailboat