Thankís for the link, it is very informative but it doesnít address the fin size or type for a 6.5 freeride sail for the Futura 133.
Iím in a similar boat as the original poster. I am also looking for a small fin for the Futura 133 but with a different twist. I have an Isonic 101 that I use for racing and I would like to get a fin for both the Isonic and Futura. The fin would be 40 or 42 cm for the Futura with a Naish 6.6 Sprint or the Isonic with a Naish 7.6 Stealth. I do have a Maui Fin Company 38 cm slalom fin for the Isonic so Iím probably looking at a 42 cm fin that I can share with both boards. The problem is there will be a compromise if I get a freeride or a slalom fin. The question is which is the biggest compromise, slalom or freeride?
For the record Iím a little over 79 kilos.