Thank you oldskool. You hit the right button. And Oceanmotion, I realize I sound like an old hippie and obviously did so on purpose. Sorry for seemingly stealing your topic for a political statement, but I did put in an underlying message that Oldskool has distilled from what I wrote, so someone caught my drift.
It's the sum of man, rig, fin and board which we need to look at. By getting rid of one of the variables the answers on the question at hand will tend to become extremely technical and physics will ultimately be the leading science doctrine as it is, or has been for ages to get a grip on questions like this. And then I am referring in general to technical questions on challenges at hand, seen from a designers perspective. So indeed, as Oldskool rightfully understood, I am referring to organic evolution and cell biology with a reason.
When designing a car and your aim is to go fast, "all" you need is the right streamline, powerful motor, a steering wheel, throttle and put a sucker behind the wheel willing to push that throttle. The end effect will be an end speed which is similar every time any man, woman or child capable of doing so hits that throttle. On a windsurfboard there will always be this mystical element.
Put two riders of exact the same weight and power on a board and one will go way faster than the other without an objective observer being able to see just why this difference is there. It's the subtle balance that makes this sometimes massive difference in speed. This is to me where the magic comes from in speedsailing and to me this is where we should try and get answers from. The answer might lie in personified possibilities to adjust the rig to one's style. In other words, the forces one uses to control the whole set. When we would put sensors on the worlds best riders, MASSIVE differences would emerge from the data collected on the water. Pressure on fin, mastfoot, pull on the boom, overall balance, will show to be extremely different per rider. So my main question is, would it be possible to even get close to defining the right amount of twist given the variables at hand when simply focussing on physics.
This is what I meant to say in my first answer. Only by taking a birds eye view and incorporating the person steering the vessel into the equation one might get useful answers. Generally speaking we know the rider itself is the limiting factor and this is a clear breach with for instance sailing. Our biggest gift to go fast seems to be the individual talent of a given rider to feel all variables at hand and get the best out of the set he or she is using.
Now there is one constant factor and that is the fact that any human body will face limitations related to strength. Hence my question: why not design with this fact of life in mind and think outside the box.
How could we organically evolve as species....so man/woman, board, rig, fin interconnected as species: windsurfer.
We still live within the Descartes doctrine of man as machine. Herbert Spencer has proven to be right in distilling the core from "origin of species" by proclaiming a "survival of the fittest" society that could and would lead to a few in charge. George Orwell has seen Big Brother before we handed out ourselves to this force that controls our lives and makes as numb as society in which indeed in name all sheep are equal, but some are more equal than others as written in another of his now world famous novels.
I wanted to add a deeper perspective and did so with the hippie era in mind, that amongst other things gave birth to our beloved sport. What if we look deeper into this matter and "imagine" with John Lennon. What if we forget about boundaries, borders, our little problems which are nearly all related to try and preserve what we have, mostly at the cost of something else.
What if we, as mankind start thinking from another level and accept we don't hold all the answers as the science on which we base our knowledge is limited, simply because we are limited. We are transmittors and recievers like for instance cell biologist Bruce Lipton says. Scientists like him and for instance Rupert Sheldrake were laughed at not long ago and seen as fake scientists mixing up wild ideas. In the now, I am one hundred percent convinced history will prove ideas spread by people like them will help us to evolve simply because their views, which are organically based, hold answers which the church of science has looking away from for centuries.
Just an example of one of Bruce's lectures.
Now translate this all to our computer era and you'll understand why organically growing computer systems will take over the world and come up with solutions we could never think of ourselves. It's simply because of this reason that science will (have to) make a shift from physics to cell biology as leading science. In other words, we need to start listening and incorporate all variables to come up with solutions, also solutions as "simple" as finding out how much twist would be needed in a sail.
And you know, I understand if people think "wtf" about the things I write. But I care about those who do are open to think deeper and understand there is a another meaning to all we do as person and society. Windsurfing as a sport could be used to get closer to the dream John Lennon wrote about. What if we can use this newly required knowledge based on cell bioligy to redesign our complete thoughts. And yes...this has to do with sailtwist, whether a given reader understands or not.
: No, it is a decrease in drag. But of course, that does increase the Lift to Drag ratio. 
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