This is Part Four of a six-part series on Learning to Sail excerpted from Colgate's Basic Sailing, used as a text at the Offshore Sailing School. Steve Colgate calls upon a vast experience gleaned from teaching thousands of students and competing at some of the highest levels of the sport. His clear and straightforward approach focuses on reasons why a sailboat moves with the wind the way it does and seeks to allay the fears of beginning sailors. (Review Part Three.)
Knowing what's going on beneath the waterline lends insight into sail trim, especially in small boats.