Jake,
Under portsmouth they show a formula 18 class prior to the F18 class. So, 18, 18magnum, Formula 18 and 18SX. All the same platform. I even have the specs for formula 18 which is the class I was reffering to. It comes up under non-participating classes. As you know even Hobie USA gave up on the Fox. BTW, got a call the other day from the guy that has my Fox and he's really enjoying it. Hope he never sails it very hard, it will most likely break a dagger again.