Timbo,

The North American F18 Class Association has the same rules as the International F18 Class, with a few exceptions, mostly because there is no infrastructure to have every F18 go through Measurement and obtain a Measurement Certificate. A Mystere Twister participated in the 2002 North Americans held in Traverse City, MI. The NAF18 Class welcomes all F18s, regardless of who built it. The fact that the majority of the F18s competing in North America are either Hobie or Nacra is an indication of marketing, not restrictions by the Association.

Chief Measurer
North American Formula 18 Class Association