Also being a visual learner, I can appreciate Pete's comments. If anyone has a copy of the old warhorse "Sail Power" by Wallace Ross, there is a lot of good info on vang and traveller sheeting and sail twist with lots of pictures and diagrams to boot.

Some people say that the book is out of date with regards to its THEORY (slot effect, etc.), but regardless, the PHYSICS of sail trim are as eternal as the particles that create them. So this book still has much to offer and always will, IMHO.

Check it out.