It is hard to organize trip to L?deritz or Lapalme to make some numbers.
We have plenty of land that could serve as well in the middle of civilization and comfort.
With possibility to achieve optimal conditions 24/7/365
My most recent idea is to create ring course.
Instead of straight line that require instant acceleration and deceleration, we could inclemently increase gain speed, constantly.
Whole concept require plastic tunnel above and powerful wind turbines running on solar panel or wind turbine 
So assuming that we have unlimited funds ( for example by converging rich sponsor from rugby to water sports) we could do some preliminary assessment:
-how much it may cost
-what are required dimensions
1.The first question will be:
What are parameters of our water run , for comfort and safety>
Assuming that we sail constantly on the curve , with optimal wind angle.
What will be radius for speed board at top speed max above 100kmh/h ( ?> 50 knots) to take that bend comfortably? 500M diameter or more? b) what is the width required for comfort and safety?
10? 20M ?
c) what is optimal depth? assuming that we have artificial means to extinguish all bumps and waves? I guess that for pure safety rezoning water should be deeper then 30cm required by top speed vessel
if we could make this 1m or deeper we could utilize the same channel for speed foiling.
d) the high of that tunnel? 6 is min but 8-10 or more shouldn't be more difficult.
Height is important because in our artificial green house , we need to provide laminar flow of air.
At the basis of this concept is creating wind, at almost perpendicular angle along whole ring. By series of grids- like our automatic transmission in the car.
3. Then we could calculate power requirements to artificially tumble the air inside whole channel
I guess that before we may have our ultimate 365 days speed runs, smaller version could be created around the world as recreational parks. Instead of swimming pools and stations converted to beach by electric fans ,we may have permanent installation similar concept to ski fields in the middle of desert.
Water park could be just 100 _200 meters in diameter ring covered with greenhouse plastic.
wind moderate 15-17 ktn inside.
btw. Futuristic design could involve solar chimney. In such example our wind is created by chimney and air warmed by sun.
This design could produce electric power at the price competitive to solar panels or wind turbines alone.
This design could be then easy to find a sponsor and could be self funding or even highly profitable venture.
My project is not as absurd as it may sounds at first glance.
Nowadays we have investors in green energy products -wind and solar, counting billions of dollars.
If we have our preliminary data: what we want. we could just walk to investor office and present business case,
idea of water park, speed run inside solar chimney fields.
But we need to have some ideas ready and propose business plan,
If for commercial tourism, one in the world artificial speed run and adjustment water park have
commercial future?
Hotels for international tourist could double the income from energy alone.
Our speed run, water park may have solid financial footing !
But our investor needs to know our requirements in advance, Height, width , depth....
-If we have accountants in our group ,we could calculate how many tourist we may need and what income could be
-engineers in our teams could draft plans for water way , and grids, air redirectors for optiman angle of attack
-our sailors could advice what that dimensions are required for safety and comfor.
I could imagine that this solar chimney could accommodate multiple rings inside for different needs: recreational wingers and beginners windsurfers, advanced , deep and shallow water,
Wind speed will increase with smaller diameter, so for our top speeds we need to decide what is the tightest curve the speed sailor could take ?
Sorry, No kiters allowed !
So are you envisaging airflow inside this donut to be analogous to the current in this toroidal inductor? (if it was laid flat on the ground) If it was even more loosely wound it would be close to 135 degrees off the wind all the way around. It'll have to have more that 30cm of water in the bottom, 50cm is the minimum for a speed record.
The big question. Is it still within the spirit of speed sailing? This question was raised when the first speed channel was dug. After a while it will become acceptable. i don't think firing someone out of a cannon with a charge of compressed air will ever be considered sailing though.
I'd think it might be possible to keep a contained vortex ring energised with fans in the ceiling. If the fans were all angled about 45 degrees towards the circumference direction rather than blowing in a radial direction to the centre of the donut, it might be possible to have a circular downwinder rather than a circular beam reach.
Going to youtube gets you hooked into all sorts of interesting stuff. Here's that famous poem again.
Is AU 5/3 taken as a sail number yet?
We have exactly this, under construction in Europe (Cadarache, south of France).
It is now about 80% complet I believe en.wikipedia.org/wiki/ITER
I wonder who will be the first speedsurfer to use it
Select to expand quoteIan K said..
So are you envisaging airflow inside this donut to be analogous to the current in this toroidal inductor? (if it was laid flat on the ground) If it was even more loosely wound it would be close to 135 degrees off the wind all the way around. It'll have to have more that 30cm of water in the bottom, 50cm is the minimum for a speed record.
The big question. Is it still within the spirit of speed sailing? This question was raised when the first speed channel was dug. After a while it will become acceptable. i don't think firing someone out of a cannon with a charge of compressed air will ever be considered sailing though.
There are few methods to deliver wind inside our toroid:
1> If we could relay on external wind , that will be the cheapest option, and simple vents outside could redirect air to inside , or suck of . amplifying at same time by using Venturi effect.
2> But wind outside - there is our common problem, rather lack of wind is our problem, so artificial wind by series of fans, powered by electricity . Significant savings is made because air is cycled inside our tube , so kinetic energy is preserved, we loose only those on friction . I imagine that we could not recycle wind under the track, so rather we need double roof cavity, where fans are installed.
Indeed we don't want to exact 90 degree angle of attack, but also forward movements. So our air will circle inside tube , exactly how your coils demonstrate but inside the tube.
It is hard for me even start imagine what sort of energy is required to circulate air in such way on our scale. Kw? MW? GW?
3.Industrial plant _ Solar Chimney is the best because solve ALL OUR PROBLEMS including funding and wind. There could be too much wind !!!All we need is simply set a track / circular channel with water. In this design Sun heat the surface , then air , and then hot air rise in the chimney. There higher chimney is the better " suctions"
Chimney will use most of energy to power turbine to create electric energy for sponsor/owner , but there should be still enough for us to enjoys free sailing.
Select to expand quoteIan K said..
I'd think it might be possible to keep a contained vortex ring energised with fans in the ceiling. If the fans were all angled about 45 degrees towards the circumference direction rather than blowing in a radial direction to the centre of the donut, it might be possible to have a circular downwinder rather than a circular beam reach.
Wow, I fall i love in physics girl instantly and subscribed to the channel. 
Beat Myth Busters hands down !!
Select to expand quoteIan K said..
Going to youtube gets you hooked into all sorts of interesting stuff. Here's that famous poem again.
Is AU 5/3 taken as a sail number yet?
Turbulence is not really well known problem.
The most clear is turbulence in plasma fusion reactors , where blobs suddenly escape magnetic field and damage whole device walls.I have my own theory in this matter and how to resolve it even exploit for our benefit, but subject is a bit outside our windsurfing scope.
Select to expand quoteMacroscien said..Ian K said..
Going to youtube gets you hooked into all sorts of interesting stuff. Here's that famous poem again.
Is AU 5/3 taken as a sail number yet?
Turbulence is not really well known problem.
The most clear is turbulence in plasma fusion reactors , where blobs suddenly escape magnetic field and damage whole device walls.I have my own theory in this matter and how to resolve it even exploit for our benefit, but subject is a bit outside our windsurfing scope.
Nonsense - turbulence quite well known - it is in everything that involves fluid-flow. Space flight is full of modelling/understanding, from capsule re-entry to rocket-exhaust:
-
Select to expand quoteMacroscien said..
Turbulence is not really well known problem.
Well Richard Feynman agrees with you on that one Macro.
"the most important unsolved problem of classical physics."
arstechnica.com/science/2018/10/turbulence-the-oldest-unsolved-problem-in-physics/
And there's a million dollar prize for you if you can polish the rough edges on the understanding of the Navier Stokes equation.
en.wikipedia.org/wiki/Navier-Stokes_existence_and_smoothness
Select to expand quoteMacroscien said..
It is hard to organize trip to L?deritz or Lapalme to make some numbers.
We have plenty of land that could serve as well in the middle of civilization and comfort.
With possibility to achieve optimal conditions 24/7/365
My most recent idea is to create ring course.
Instead of straight line that require instant acceleration and deceleration, we could inclemently increase gain speed, constantly.
Whole concept require plastic tunnel above and powerful wind turbines running on solar panel or wind turbine
So assuming that we have unlimited funds ( for example by converging rich sponsor from rugby to water sports) we could do some preliminary assessment:
-how much it may cost
-what are required dimensions
1.The first question will be:
What are parameters of our water run , for comfort and safety>
Assuming that we sail constantly on the curve , with optimal wind angle.
What will be radius for speed board at top speed max above 100kmh/h ( ?> 50 knots) to take that bend comfortably? 500M diameter or more? b) what is the width required for comfort and safety?
10? 20M ?
c) what is optimal depth? assuming that we have artificial means to extinguish all bumps and waves? I guess that for pure safety rezoning water should be deeper then 30cm required by top speed vessel
if we could make this 1m or deeper we could utilize the same channel for speed foiling.
d) the high of that tunnel? 6 is min but 8-10 or more shouldn't be more difficult.
Height is important because in our artificial green house , we need to provide laminar flow of air.
At the basis of this concept is creating wind, at almost perpendicular angle along whole ring. By series of grids- like our automatic transmission in the car.
3. Then we could calculate power requirements to artificially tumble the air inside whole channel
I guess that before we may have our ultimate 365 days speed runs, smaller version could be created around the world as recreational parks. Instead of swimming pools and stations converted to beach by electric fans ,we may have permanent installation similar concept to ski fields in the middle of desert.
Water park could be just 100 _200 meters in diameter ring covered with greenhouse plastic.
wind moderate 15-17 ktn inside.
btw. Futuristic design could involve solar chimney. In such example our wind is created by chimney and air warmed by sun.
This design could produce electric power at the price competitive to solar panels or wind turbines alone.
This design could be then easy to find a sponsor and could be self funding or even highly profitable venture.
I posted this back in 2016. Didn't get many bites!! Just keep sailing round on one tack till your thighs start burning!!
Whooooaaaaa! 
That makes me giddy just thinking about it!
But I actually think that concept could work! 
I think you could count on the concept to already be proven. All you've got to do is complete the loop. A more aerodynamic roof would help.
With the advent of foiling you wouldn't need as much wind. And given that it's possible to carve a foil without halving your entry speed, proper slalom races.... linked turns, counter rotation and all that.. would be possible. Round robin, parallel slalom, that'd draw in the spectators maybe?
Opening shots are at Roundhill, Tekapo, NZ. For some reason this where a lot of the US team went, or maybe still go, for summer training.
Diagrams?
