Here's a question for all you engineers out there (or anyone else for that matter..). On the one hand we're told "flat is fast" - make best use of the aerodynamically (should be aquadynamically ?) efficient shape of the hull. On the other hand, when sailing downwind in light airs, then pronounced windward heel ("reduce the wetted area") seems to be more effective. What determines the point in sailing downwind where the windward heel becomes more effective than sailing flat? Presumably when the drag effect of a flat hull (with large surface area in contact with the water) is greater than the drag effect with a reduced surface area in contact. But is this point measurable? Also, if this works downwind, would it not in theory also work upwind? Although balancing the boat might also be next to impossible. Anyone ever tried it??