Thanks for all the 18 to F18 conversion info. I am measuring and remeasuring now. When finished I will have a 1982 Hobie 18 magnum with square top Tiger main, SX mast, Elliott chute ( cut for tiger), end pole snuffer system, carbon daggers and rudders. Power down haul and 9-1 main sheet system. I plan to race it with the wings on. I assume I will race open class but not sure. Would I run with other 18s' and give them time? Is there a portsmouth rating I would apply? I won't race much so want to be sure about classification before I show up somewhere and they can't decide what to do with me. Thanks in advance.