>|> I had an argument with a friend who has a sail boat, and I told him
>|> that a board could run faster than the wind speed, he claims that it
>|> is impossible. Was I correct? I mentioned Bernoulli's(?)
>|> principle...but I'm not sure what is this principle...
>This issue has been debated to the death in the past.
>Let me summarize the major results of the debate.
>1. Bernoulli's principle has nothing to do with moving faster
>than the wind. One posting (from an apparently authoritative
>source) claimed that Bernoulli has little to do even with the
>force on the sail itself.
>2. The relative wind does not really help, because it only
>adds to the wind component that comes straight down at you.
>3. It all boils down to a balance of forces on the board.
>The sail generates a strong lateral component, balanced
>by the skeg, and a small forward component, balanced by
>the resistance to forward motion. This resistance is
>small for a planing board, so it can go fast. There is
>no reason why the speed of the wind should be a limit.
My iceboat can certainly go faster than the wind speed,
and so it wouldn't surprize me that a fast sailboard could
too. But I saw the word "run" in the original post and
assumed that the writer was asking "can a sail powered
craft go faster than the wind straight downwind (wrt to
the actual, not apparent, wind)?" When I jibe my iceboat,
I do coast through the straight downwind heading with an
apparent headwind and thus my speed exceeds the windspeed.
But, I remain to be convinced that I could continue to sail
straight downwind for very long with an apparent headwind
from dead ahead. I would have answered "no" to the original