The Formula Duo Weed is all you need. The "Formula Duo" is 40 cm (the largest Wolfgang makes).
The 36 cm Duo Weed would probalby work with your 9.5 if you are sailing powered up.
The "duo" simply means the fin is Wolfgang's asymmetrical design.
Convex at the top on one side....concave at the same level on the other side.
Convex at the tip on the opposite side from the top/base of the fin and concave
on the opposite side in the same area.
Wolfgang has worked out (many experiments and prototypes I'm sure) what percentage of the
fin needs to be convex to give the board good balance and spin out resistance.
No one else does anything even close to Wolfgang's asymmetricals.
Some of his speed asymmetricals are amoung the fastest on GPS Speedsurfing.
The rake angle of Wolfgang's fins can be a bit steeper as the weeds go off around the
foil of the fin, rather than sliding down like all other weed fin designs.
Have you tried a Lessacher duo? I've tried some of your other suggested weed fins,
and several more that are not on your list.
Given a choice, I'll sail the Lessacher Duo as it seems to out perform all the others overall.
Last edited by Roger; 5th March 2012 at 01:43 AM.