| Once moving a high aspect board (or rudder) is a much more efficient way to generate lift to counter leeway.

AFAIK, for any given weight, $, or (wetted) area unit of material, nothing beats a foil for most lift per drag and weight.

There are many ideas on how to add lift to foils, or make things perform like foils, but all of them I have ever seen are poor in comparison.

| Modern high performance multihulls are making use of cambered boards to prevent leeway thereby avoiding induced drag on the hull.

And they are using modern foils because there is no better option.
Sometimes, in some specific boats and planes, adding some sort of device to an old design might give one a positive effect. Enough to justify said devices existence.
But if building from a blank sheet, nope.

And to be clear, this is not only about go fast high performance. One can do a lighter and cheaper low performance boat following the same ideas. Foils are just a better idea across the board.

| A cambered board is the most efficient for a proa because it can be made bi-directional with relatively sharp edges because it should be designed to operate at zero AoA when the boat achieves best VMG.

Rick, can you clarify this for me.
I don't understand how a cambered board is most efficient, BECAUSE it can be made bidirectional.
I am not even sure a cambered foil is most efficient. Do we know that is always the case?
And would it not be odd for a foil to be at 0 AoA when the boat makes best VMG?

| There will be a little positive leeway when pinching up and negative leeway if sailing low and raised once reaching.

Specifically regarding positive leeway while pointing. I have read about this a very small bit. I was thinking it was because most boats dont have two rudders, and this was as best as could be done. But, I was thinking, with two high performance rudders one would be better to adjust them for zero leeway. My thinking being better to load the foils than drag the hulls.
Is that wrong?