those who know me well also know that I am a Physics buff. Every now and then I just have to delve into the physics of things. I am sure I am not the only one around here who loves this stuff, especially given the fact that one of the list's members holds a PhD in Physics and has several years of experience in actual research in laser technology. In fact he was once lightly wounded by a laser - or was it phaser? :) Makis, can you end the confusion here?

Anyway, something that I had been meaning to do for some time was to look into the physics of sailboats as there are concepts and facts there that are quite simply fascinating and amazing. For instance: How can sailboats sail upwind? How can sailboats sail faster than the wind? What does the term "she makes her own wind, laddie" refer to?

A concise and fairly accurate primer into the physics of sailing is here (although it does downplay the significance of the Bernoulli effect which in some configurations can be very important indeed and is what makes a boat "generate its own wind" and also what makes footballs follow elliptical paths)

http://www.phys.unsw.edu.au/~jw/sailing.html

after digesting this you can do some quite cool virtual sailing here:

http://www.nationalgeographic.com/volvooceanrace/interactives/sailing/index.html

Pretty much after this all you need to actually sail on your own is some practical skills priming here:

http://www.sailingusa.info/sailing_primer.htm

Now, go rent yourself a sailboat and after a couple of rides with an instructor you should be able to take her on your own.

Now about the bernoulli effect which is quite fascinating and among other things it is also the reason planes fly.

http://www.rz.uni-frankfurt.de/~weltner/Flight/PHYSIC4.htm

The bernoulli effect is very important in sailing as well. Some people have tried (quite successfully) to boost its effect and make ships that sail using the bernoulli effect as their main or only means of propulsion. The first ship I know of that did that is Flettner's Rotorship:

http://www.efluids.com/efluids/gallery/flettner_rotorship.html

An easy to set up proof of concept:

http://www.mip.berkeley.edu/physics/C+25+0.html

An even easier one that I just thought of:
- Spin a spinning top
- Blow on it
- Watch it predictably move to the side but always toward the right or the left (depending on whether the top spins clockwise ot counter-clockwise)

* If you try this, tell me if it actually worked! :)

A more modern aproach to tapping the bernoulli effect is Cousteau's Turbosail (first implemented on a ship called "Alcyone", and frankly looking quite cool):

alcyone: http://www.dolphinlog.org/alcyone.htm

and here: http://www.cousteausociety.org/tcs_vessels.html

and here: http://perso.wanadoo.fr/b.mauric/alcyone_an.htm