I have an 8.0 and a 6.5 Retro that I'm having a little trouble rigging on days when the 8.0 is a too much but the 6.5 isn't enough. I rig the 8.0 on a 75% Powerex mast and the 6.5 on a 75% Sailworks mast.
For the 8.0 when I apply medium downhaul the batten above the boom moves back but the top of the sail doesn't show much looseness. To get the top to open the batten is way behind the mast and I don't have much power.
The 6.5 kinda works in reverse of the 8.0. To get the batten to move beside the mast so that it will rotate the top of the sail is very loose and again I do not enough power in medium wind.
My 5.5 and 10.0 Retros rig about like I think they should.
Do you any suggestions about what I might do to get more range out of my 6.5 and 8.0.