Used sails are hard to judge. While you can look for tears, worn or frayed areas, it''s hard for most people to see if a sail is "blown out", even if it''s up. (The dacron in a sail can last for 20+ years, but the shape may have dissappeared in 2.) Newer materials like kevlar are harder to gauge because the material (and shape) may look fine right up to the point it fails. Worn, "fuzzy" areas, or pieces that are coming unglued (delaminated, in the parlance)are obvious concerns that may be fixable. We have found that sailmakers are helpful in determining how old sails are, what needs fixing (and can be) and what isn''t worth fixing (or can''t be). It''s an adventure.