I would think a cross cut Dacron sail made with a high performance
cloth would be fine for a 24 foot boat. If you wanted to step it up a
notch go with a tri-radial laminated sail which uses Dacron or Pentex
between the mylar skins. Any sailmaker who is pitching you on Kevlar
or any other exotic (read expensive) cloth for a 24' boat is not
serving you. This is assuming of course that you are not going Grand
Prix racing. A good friend who has owned 2 lofts (major franchises)
told me once that the use of exotic crap on boats smaller than 30' is a
waste since the loads just arn't there.