EDGARTOWN — The first thing you notice about a kiteboard is how ridiculously small it is. It is so small, it makes a luge seem roomy. So small that what it can do — carry a grown man at speeds approaching 60 knots — seems, at first glance, impossible.

Then there are the courses where kiteboard riders seek to achieve these speeds: shin-deep stretches of water no more than a few feet from shore, in places where winds routinely reach gale force. Places where success can mean traveling faster than any sailing vessel ever to knife through water, and where wiping out can mean broken bones, and worse.