Originally Posted by Farlo
A 34cm fin will work with an underpowered 5.5 and an overpowered 7.2 but you may not enjoy it at both ends of your wind range. IMHO ideal sizes for your sails/weight would be 30/31+36/37, quite a large gap however. You can probably reduce it to 32+36 as Naish Sprint 5.5 is still "at ease" in 20 knots.
Thanks for the recommendation. Probably, i will choose this combi 36 / 32.