Here is a terrific top-of-the-rig shot showing a "Blown Out" dacron mainsail. Look at the draft stripes showing the aerodynamic shape of the sail; they look like backwards airfoils. The contrasting color of the draft stripes makes it easy to see the shape of your sail. In this picture the deepest part of the draft is aft of the halfway point between the front and the back of the sail. (The yellow line was drawn on the picture to see the shape a little easier.) A lot more halyard tension and Cunningham tension will help move the draft forward some, but not enough. This sail is too far gone. Hence the reason this team uses the sail for its weeknight races, that way they save their new main for the important regattas.