RE: Formula questions
Sorry for the delay, but the forums have not been working at all (as I'm sure you know).
I'm still concerned with you getting the 100 cm wide F-147 and trying to use it with your 8.0 m2.
It's going to be difficult to get a good balance or to get the "total" performance from the board with such a small sail.
The 70 cm fin is definitely too big for the 8.0 m2 unless you are really in marginal conditions and need the extra fin size to get planing.
The 58 is probably going to be an OK match with the F-147 in 15 knots and up, but a fin in between would be preferable. Something in the 62-64 cm range would probably be ideal.
Hope this helps,