we use in Slalom Comp. for iSonic111(mod.2010):
as biggest S1 39,5cm (Refelx 8,6 and 7,8)
smallest S1 36,5cm (Refelx 7,0 and 6,2)
in your weight the 42 is much to big and you will not get a free planing of your iS111! It will run deep and like on rails.
BR pfaffi (www.pfaffi.at