Not using battens causes the leach of the sail to flap, wearing out the cloth, causing the hem to tear off. If you really hate using battens, have your sail maker cut the roach off the sail so that it will set properly without them, or, check back here in early 2001 for repair tips on how to do this yourself. Store sails away from sunlight. UV radiation is the most powerful destroyer of sailcloth. Store sails where mice can't get at them.
Mice can make a real mess of a sail.
They chew up the cloth to use as nesting material. Rodent damaged sails often look like total write-offs. Don't throw such a sail out though, they will often be quite serviceable after being repaired using the techniques described below. Depending on how big the patch is to be, this can be more difficult than it sounds. Sails are designed to have curves in them, and therefore don't lie flat.