genaker is a good option
I fly a gennaker (UK sailmaker flasher) on my hunter 310 with superb results. I had it made for my past boat, a S-2 9.2C (I=40', J = 13') It is not a perfect fit as the hunter is a fractional rig. But it is close enough to be a big success. My gennaker is .75 oz. nylon and is 770 sq feet. (for comparison, a 150% genoa is 390 sq feet. I can only use it in winds less than 10 knots, but I can use it on a beam reach. A close reach gets tough. Bottom line: for about the same price as a genoa, a gennaker will get you a big colorful sail that loads of fun and flys you past other boats. TP