http://www.youtube.com/watch?v=uMd7cnTtG8Y

Absolute glass! This is cool. i would be fuming and pissed that i was drifting in 2kts of wind...they are flying a hull.

cc

This video has been discussed before and the conclusion was that there was more than the usual wind speed variation between water surface and higher up, probably due to unusual water-air temperature gradient.

In other words, even if there´s virtually no wind near the water surface, the sails are seeing more than 2 knots wind.

that makes it even COOLER! i need a taller mast apparently.

I think I have sailed on that same lake, Lake Constance, with Andi Lutz on his F18HT, from the Swiss side. They race late in the afternoons on weeknights. When I first arrived there was NO WIND on the lake, yet there were many cats rigging up at about 5pm. I'm thinking to myself, "What are they wasting their time for? We can't sail in this, it's DEAD out there!"

When I asked Andi about the lack of wind, he said, "Just wait, it will come." And sure enough about 6pm, it slowly starts to blow, very light at first, but steadily increasing to about 8-10 as it got later. We had a great time racing!

Andi said in the summer, the heated air is rising up the side of the snow capped mountains during mid day, but as soon as the sun gets low, the air right over the snow cools and sinks quickly, and it comes rushing down the mountains and across the lake, creating the good wind after 6pm!

They have a name for it of course, but I can't remember it. I guess the mast in that video is high enough up to grab the wind before it sinks all the way to the surface, leaving a nice, clean, glass-like look to the lake as they scoot around at 14 knots!

It`s called katabatic winds... It`s not good for flying paragliders in, don`t ask me how I know..
Timbo, I thought you would have learnt about it in fly-school ?
Not that aircraft the size you fly would experience it, unless you were into a late aftrenoon ridge-soaring flight, which I think would get you grounded by your airline .

I've had something similar when I was sailing the FX1 on our lake a few years ago, the water was almost mirror-like (not as extreme as in the video) but still I was flying a hull most of the time under spin.

Timbo, what great time we had then!!
The wind is called the Biese (a cold breeze from the north east)

It's amazing Vid!

During winter and early spring sometimes the wind dosn't get to the surface of the water because of a cold air layer (cushion). And I also think that cold air has much more force. Thats why they fly in that litlle wind.

But that YSA 30 in the vid, still waits for his moment on the race course, compared to the Ventilos 28 and the RC27.