For anyone who cant sleep at night and needs some aid..
under: Airfoil - wingmast - pdf version
This article really applies to land sailers but its certianly applicable to a mono slug sail when used without a jib in higher winds.
The thing I wanted to point out is something very roughtly derived from figure 1 but it shows that about 22 percent of the sail lift is derived in the first 10 % (leading edge) of the sail area. If you screw that first 10% up (such as with a non rotating mast and with the sail sheeted out), your guess is as good as anyone elses about what happens but I think you lose a lot of what a sail is supposed to do.
Some more of the quick and dirty conclusion to get the 22% is given below:
On the x scale on the figure 1, there are tick marks that divide the sail in to 10 zones starting at the front of the mast and ending at the leach. On each zone, I made a rectange which approximated the total area of the positive and negitive pressures which I beleive is a direct correlation to the lift generated in that section. I then compared the area of each rectange to the total area and assume this gives the percent of lift that area or zone produces. This was a rough and not too accurate measurement but here are the results:
Zone % of lift
(ie, zone 0-1 is from the leading edge of the mast to 10% back - first 10% can generate 22.6% of lift "if" done correctly.