(38 cm ) Maybe it's a bit exaggerated
recommended fin range 38-50 = most minimum to maximum most
I saild it with a MFC 44 cm rc2 (i'm 87kg) and with a 7,8m and 8,6m sail
I think its to small (It only works in very strong winds)
Normally I use a 46cm fin with my 7.8 m sail. (select, fin with a lot of lift)
It would at least be a 45cm
And a 9.7 m sail on it works perfectly with a 48 to 50 cm fin.
fins bigger than 50cm also give no further improvement.