Originally Posted by Al Stein

That seems to be how most people do it... just for completeness sake, amd alternative is to do it the way full size boats do it.

On the water we don't choose an absolute sail position and set it: we watch how the sail is acting in the wind and adjust it in or out as we feel is needed. To do that on an RCboat, you use a centering stick and move the stick to command change in or out rather than to command absolute position.