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.
Thanks for the tip. I did stumble across Bacon''s web site and they say to test with a sail needle. Trying to pass the needle through the sail cloth you should get some resistence and not hear any poping sounds.
The sounds you get from passing a needle through the cloth will vary depending on what the cloth is made of and what it may have been treated with by the manufacturer (plastic coatings stabilize warp and woof before the sailmaker gets it). I''ve never heard popping sounds, unless its the sound of the stitching pulling out when you should have reefed earlier.
A high-level kind of test seems to be to check if it''s crispy or nice and soft. You DON''T want the latter, not even on Dacron sails, since they also typically have been coated with some wax-like feeling material that gives as the sail is used.
If the sails are crispy, you are typically in reasonable shape.