Hi everybody (Iím the initiator of the thread)
Two M6 x 100 screws are definitely the wright ones for my board, as I already tried them on (for simple tuttle fins). Maybe M6 x 95 could also work, but not shorter.
Now Iím thinking that maybe the quotation on the fin-bolt-chart (two M6 x 60 for simple-short tuttle fins) is for boards that have those walnut size (oval) holes on the back of the deck (above the finbox) and the screw holes are lower compared to the deckís surface. So the screws go lower than the deck.
My board doesnít have those and instead it has the screw holes right on the deckís surface. On each hole it also has a white rubber washer (glued on the deck) and for each screw head I also got a white rubber protector (plus the metal washers). Obviously this setup needs longer screws than the other above (with the walnut size holes).
To REMI and ROGER: Is this the explanation of the difference? And why are some boards made with different kind of fin box (like mine)?
Thanks again everybody