The Portsmouth Fleet, the handicap fleet.
Normally to race as a one design fleet, 3 or 5 boats are required. If there are less than that, you race in the handicaped or Portsmouth.
In this are the boats that are making class are the H20 and the A-Class. Next year we will probably see the F18 make class.
The Open 20 and Open 18 Class was based on race results in our area. When you group the boats in 18 ft and 20 ft groups the finish times correlate with skipper skill not Portsmouth number(with some notable exceptions, like the carbon 18 sq meter). From what we could tell the speed of the 20 ft spinaker boats were all about the same. Based on this we planned to race the 20 ft spinnaker boats in an informal "F20" class or open 20 class.