iSonic 101 and the right fin

[Jules Gorris]

Hi Kevin,

I just bought a 2010 iSonic 101 (WoodCarbon) and I have RS Racing Sails 6.2, 7.0 and 7.8.
I am a 80kg sailor and I have a question which size of fin I schould use.
Most of the time I surf on flat water, sometimes with more wind a bit choppy.
My intension is to buy Select fins. I can choose between several types:
Elite S10 XL-Slam or Elite S11 Slam or perhaps the Elite S09 Casper GPS-Speed.

Most of the time I will be using the 7.0 and 7.8 sail. It would be nice to have just one fin with which I can sail both sails (?).

Thanks for your help,

Jules