My name's Charlie. I'm a big fan of sailing and skateboarding, and decided to see if in a strong wind I could get much speed by combining my little board with an umbrella (reinforced with strings to resist collapse), on a day with 30mph winds.
The results were great, and I was even able to maintain speed up gentle inclines. It was a real test of nerve at times, as I was having to balance the force on the umbrella with controlling the board - imagine windsurfing but with hard ground instead of water to punish a mistake! At higher speeds I'd enter a 'death wobble' on the board, so I had to de-power the umbrella by tilting it upwards, to slow down.
It was a great experience, and I've used the same umbrella on my kayak for good downwind sailing on the Thames. Sometimes the simplest ideas can be the most rewarding!