Sail Area to Weight Ratio (Upwind Ratio, Downwind Ratio)
This calculation provides a simple comparison of the upwind and downwind speed potential
of a given design. To calculate the upwind ratio use the full area of the main and jib,
adding the area of the spinnaker (if any) to calculate the downwind ratio.
Caution & Warning....
As with most ratios like this you must make sure that you're measuring displacement
and sail area the same way for all the boats you want to compare. Also, keep in mind
that this is a fairly simplistic calculation that does not take into account major
factors such as ballast/crew placement or rig and keel geometry. As such, it is most
valid when comparing boats of similar size and design.