How can you tell if a sail is in good shape?

[jack]

I know this sounds like a stupid question but how do you tell if a sail is in good shape or needs to be replaced? The sails look like they are in very good cond. My concern is the main... just above the boom I can pinch about two inches that I can't tighten up, when it is full of air it is tight but the sail bows out just SLIGHTLY. Is this what people mean when I hear the sail is blown out? Does this little bit of extra sail make a BIG differance? I am just a weekend,non-racing type of sailor. Just a little more info for you, When I reef the sail is as tight as can be, maybe I should reef more often and save a grand.  Thanks to all that respond, jack

 

[Gary]

I'll try to answer.....

your questions. The bellowed out area in the center of the main is called draft. Sails are cut to have this shape to create lift, just as an airplane wing creates a low pressure area above the wing. This low pressure "sucks" it up in the air and prevents it from falling. Back to sailing.....The draft in a sail must be in the front half of the sail area to be efficient. When a sail is said to be "blown out" the sail material has stretched and the draft has moved back past the half way point of the sail. This creates drag and will move you along but you won't win races. Study your sail shape and see if you see a lot of draft just fore of the leach.