I know I am going to regret this but before I started sailing I thought that sheets were the sails. I did learn that the sheets are control lines. When new to sailing you have to learn a new language.
That is understandable, because originally the sails were the "sheets." The term "three sheets to the wind" refers to sails, not to control lines.
The terms "trim the sheet," or "sheet in," "sheet out," used to refer to trimming the shape of the sail, but over lots of time, somehow the word "sheet" got transferred to the actual line that did the "sheeting."
And maybe they stopped using sheets for sails. <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />
