Consult a sailmaker
If you can find a local sailmaker who knows his business, you can start a consulting relationship that will pay benefits throughout the life of your current and future sails. When the time comes, he will help you pick the best replacement sails for your area, your boat, and your planned use of the boat. My sailmaker has always been ready with advice about sails, running rigging, sail trim, and sail selection that has been a big help to me.
Having said that, other signs your sails may need replacing include:
- The fabric feels soft and pliable.
- There are worn out spots on the sail.
- There are places where sail threads have broken and come loose.
But shape is the key consideration.
When we replaced the baggy mainsail that cam e with Lady Lillie (on the advice of our sailmaker, that was our first move), we think it added a knot of speed and reduced heel by 5 degrees in moderate winds.