Thousands of people have raced their Sunfishes without all the add-ons. You can do so as well. Depending on your skill and that of the others, you may even win a race. But to be competitive at the highest level, you will want to dress up your fish with, at a minimum, a race sail and the plastic fantastic (foam) daggerboard. Cunningham and outhaul cleats, perhaps, but these additional controls can distract you from sailing the boat well and tacking on the next shift.