Welcome to sailtheory.zeiltheorie.nl

This site has been designed in order to stimulate the better use of sailing theory and hopefully, through this knowledge, improve your practical sailing ability.

Click on any link on the right to obtain detailed information regarding the selected subject.

I felt the need to develop this site, as there are a lot of complex and misleading theories being spread around the Web that are hard to use and in some cases, give wrong results.

Such theories are even quite commonly found being taught at sailing schools and on sailing courses.
As a result many people consider sailing theory to be useless and as such abandon the theoretical guidelines, tending to take an intuitive attitude toward learning sailing (learning by doing), which in a way is correct.
I consider however that if one learns the theory correctly this will definitely improve one’s sailing ability.

My hope is that you will find this site and the information contained therein of use.

Best Regards from

This site is also available in my native language dutch: www.zeiltheorie.nl
So, English is not my first language, so if someone feels the need to correct my English, please do.
The wrong wing theory
Why the most common wing theory is wrong.

How a sail works
Explains a wing theory that can be used for sails

The theory explained with some simple experiments.

Couples and forces
How forces and moments work on a sailboat.

Forces below the water
The keel and the rudder.

Explanation of what resistance a boat has through the water.

Why a boat tips over or not

The basis of tuning.

Frequently asked questions
Please read this before sending me an email.

Some links to other theory sites.