Can anyone help me out with the right size screw I need for my 117W isonic?
Trying to put a tuttle fin in to a deep tutlle box but the screws supplied don't fit.
Wondering if someone out there has the formula?
cheers
Maybe try thishttp://www.star-board.com/2012/products/charts.php?id=fin_bolts
Edit - Sorry, I see what your saying now. 
you need about 15-20mm longer at a guess. I use 65mm in my exocets, and have made a block from an old plastic chopping board to plug the gap above the fin - I bent too many bolts with impatient screwing (always get shouted at for screwing too quickly and not just when windsurfing), and 2 of my fins would rise up inside the box by 1mm or more at the front....cant have that now.
I dont know the thickness of the isonics in terms of how deep inset the holes for the bolts are so cant help anymore that that.
Get some 85mm screws and if to long you could cut them down. I got M6 SS 85mm bolts on my Manta.
117w you need about 90mm long for a standard tuttle fin if i remember correctly.
Il check later
