I recently purchased a Nacra 5.0 and had the same issue. I'm about 140lbs and often single-hand on a gusty lake. I've flipped 3 times in 3 weeks. The first time I had a crew of equal weight and with the bow to the wind she came over with a bit of effort. The second I was single handing and had hte aid of a power boater. (this is the ONLY thing those boats are good for). The third, I got smart and bought the Murrays Big Bag righting system. I made a 4:1 system attached to a righting line that is attached to the mast step bolt. The system is all rolled up into a small package and strapped to the front beam. The boat came over so easily that I did not even need to bring the bows into the wind. Plus the bag stays in the water after the righting so the boat can't take off on you. I highly reccommend it.

-Jeff