I have a Mk2.

Differences I saw between Mk 1 and 2

- Mk 1 non-rotating mast (early Mk 2 also had non-rotating mast)

- Mk 1 has offset centerboard. Mk 2 has centerline daggarboard. Some Mk 1 owners say the off-center makes one tack sail SLIGHTLY different than the other tack. But the centerboard does rotate up if you touch bottom

- Not sure, but I think Mk 1 sailplan is slightly different (perhaps smaller total SF)

- Mk 2 is slightly lighter

Both are great trailer-sailors and can be singlehanded. The mast raising/lowering system (with gin pole) is very straightforward.

There is an F-boat forum on yahoo groups (not to be confused with F-boats forum) that is frequented by the designer, Ian Farrier. In addition, there is an F-24 forum as well which is populated by Mk 1 and Mk2 (and a few Dash/Sprint 750) owners.