Foiling in zero wind..

[cglazier]

Imagine there is no wind and you are in a wide river with 10 knots of current.
You can sail up river (toward the source of the river) on an Americas Cup AC50 sailboat (or on a kite foilboard).

Thanks to an Americas Cup skipper for presenting this amusing scenario.
(both AC50s and kite foilboards have VMG capabilities of greater than the apparent wind speed)

CG

[edt]

We've discussed this before. There are a few locations suggested, a few rivers and of course, tidal currents. Definitely a nice stunt.

[Peter_Frank]

It is still an amazing thing, no wind at all, just the current flowing lets say South 10 knots.

Then you as a kitesurfer in the water, will feel 10 knots of wind from South going North.

Meaning, when you are in the water you drift with 10 knots going South, and when launching (with the kite North of yourself) and riding you can ride "downwind" as fast as you can, and as we know, you can have a higher downwind (and some also upwind) VMG than the 10 knots of "wind", so you can ride against the current going "downwind" and end up going more and more to North relative to land, when you are really fast

It would be pretty special though, just to ride when zero wind and fast current only, as the wind gradient in this scenario, would be much much lower than usual over land, and the "wind" would also be incredible smooth and close to "perfect", no turbulence at all - WOW
It would not matter if high trees or canyons or buildings around the river, as it would not disturb this perfect "wind" at all, really a paradoxial scenario

Also, if you did not ride a fast hydrofoil, but launched your kite, and looped it bodydragging at full pace "downwind" (towards North), you would still end up further south from your starting point no matter how good you are at looping and getting dragged really fast "dead downwind"

PF

[Horst Sergio]

Yes very nice Idea,

I also already thought about this but I am not sure if we have in Europe a river with around 8 knts of speed in the center and wide and deep enough and without to many ships ... But for sure there have to be some places in the world to do such a video. Let's wait anybody will do it.

At one of our lakes which is in a valley I had many times a similar competition: Beat the ballon. This is just a very old picture but to get an idea.



If there are the normal around 8-10 knts of wind, on the upwind side of the 6 km long lake some ballons are starting. When I see them getting up, I go upwind to meet and we have a downwind race. Sometimes the ballons are coming down to just 40 m directly above the lake (we also asked them ones to go even depper and it is no problem but haven't done a video yet).

For sure in this case the higher the ballon is, the more it is out of the katabatic wind, but often it is a fair race.

Sometimes the ballon wins, sometime me.

Must be a cool view from the ballon if your in the middle of no wind and smoking a cigarette seeing no wind. And ten meters under you a foil kiter is passing with 40 km/h "downwind".

[alexrider]

We've discussed this before. There are a few locations suggested, a few rivers and of course, tidal currents. Definitely a nice stunt.

Kiteboarding in zero wind. It's possible after all!
viewtopic.php?f=1&t=2394223

[BraCuru]

I think a river with 5 kts would be enough.
It should be to much problem to find such one and wide enough. Humber UK?

We've discussed this before. There are a few locations suggested, a few rivers and of course, tidal currents. Definitely a nice stunt

Another topic but with more difficult level:
viewtopic.php?f=196&t=2394653

[Regis-de-giens]

Sometimes the ballon wins, sometime me.

Very interesting Sergio, this proves that you have the level to ride downwind faster than wind in VMG, like this suprising machine (which bye the way is a good illustration of riding in zero wind with current only)
https://www.youtube.com/watch?v=kWSan2CMgos

[burton420]

hey cglazier i know Squamish is one of your local spots. do you think this would be possible on that river?

[Lokihel]

That car thing is actually moving straight upwind, not the same principle

If it had its propeller at 90° to its axis of travel and had a steering system that allowed it to remain at 90° to the apparent wind it would be a good illustration.
With the current set-up it can only run at very close angles to the apparent wind.

Still very cool though.

[Regis-de-giens]

That car thing is actually moving straight upwind, not the same principle

Thank you.
In fact it is downwind
(Ok but there is no wind ... )
Anyway to catch the "downwind" thing , you need to imagine you are located on the rolling carpet. relative wind will come from the left toward right , as the car does ... so it is pushed by the wind, at higher speed than wind.
It is exactly the same as kitesurfing on a river ( analog to the rolling carpet) and coming back to initial point (or upstream toward the right) without wind.

However a kite could surely not go direct downwind like this véhicule and should S-jibe with a little angle to the wind (the mechanical principle of transfer of energy on a kite does not allow to overcome the wind)