Bob - We have the same thing with our North main. I have found that the general rig tune does not work with the main.
Here are my observations (right or wrong):
Strong Breeze: 41 upper 37 lowers tight back-stay (1/2 inch of threads above/below the center bolt) - We found that with the lowers tighter the pre-bend is not carried nicely from the base up, but more from the lower hounds up. But loosening the lowers and tightening the backstay give the rig a better overall arc - which helps to flatten the lower area where the speed bubble is most pronounced.
Lighter Breeze:35 lowers 37 uppers - backstay is much looser - 4 inches of sag (2 inches of threads from center bolt) We then vang sheet the main to keep it from twisting into the slot as it is eased.
So these are somethings that we learned this year - we will try them again next year.
It would be interesting to see your thoughts on these settings.
David
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