To check the condition of your sails, hoist each one individually on a calm day and watch what happens to the shape of the sail when you adjust the luff and foot. You still can get reasonable performance from an old sail if the basic shape remains; if it’s disappeared, take the sail to a sailmaker. He or she may have some suggestions for a recut.
If your mainsail uses short battens, make sure they are thin and flexible enough at the forward end so there isn’t a hard angle in the sail where the batten stops. Full-length battens will produce a better shape; however, you’ll need to consider (and deal with) hoisting and lowering the sail. A reasonably skilled person should be able to raise, lower, and furl a mainsail of about 500 square feet without help.
If you’re getting under way and there is a question about what the weather might do, start with a reef in the main and —if you don’t have roller furling—a smaller headsail. It’s easier to change up than it is to change down. Hal Roth