I have been tapped by my power squadron to teach a new seminar course on sail trim. It's a two-hour course and I have yet to review the course material.However, I'm wondering if there exists any interactive software that will show the effect of sail controls on the shape and pulling power of a main and jib. For instance, it would be nice to see how a tale-tail responds to adjusting the angle of attack of the main or the position of the sheet for a headsail.Any suggestions would be appreciated.