Presently running my sail, HGO 8.0, 105 off the front screw with 0 shim on IQFoil (900) with -2 255 stab. I'd like a touch more front foot pressure. Should I keep moving the mast base back or is it time to go to a +.5 shim? How far back are people running mast bases on big boards (85cm wide) for light wind slalom and course racing?

On the same set up, I ended up shimming the 1000 to +0.5 and it balances out better but moved the mast base up to 107. I'm on the light side so don't need a lot of lift, just would like to use less back foot pressure in lighter breezes.

On a Goya Bolt 135 L slalom windsurfing board 80 cm wide I have the mast base all the way back to balance an AFS W95, maybe 1/4" to spare before single bolt mast base nut grabs air!

I think you'll find a lot of variation in set ups, as people have all started with different set ups and worked from there. I've got my mast step set at 111 off the front screw (just in front of the middle of the track on the jp 175) iq foil and 8m hgo, with -2stab and the + 0.5 shim. Stable, Plenty of lift, but not out of control till around 18/20knots

Sandman1221 said..
On a Goya Bolt 135 L slalom windsurfing board 80 cm wide I have the mast base all the way back to balance an AFS W95, maybe 1/4" to spare before single bolt mast base nut grabs air!

realize my kit is not exactly what you had in mind, but measured the distance from sail mast base to front screw, it is 108.5 cm, not sure if that is "similar", or not, to what Subsonic reported (111 cm), or that difference is due to the race wing being ~2.5 cm farther forward of the mast than the wing on my free-ride foil.