Emirates Team New Zealand recorded a speed of 44.15 knots, ( 50.8 mph ) ; that
is Fast by any standard for only 20Kts of wind !!!
That's what I Wanna do on a cheap kite-boad set-up, (under $5K) since
i don't have a one hundred million dollar budget, like these guys !!!
If all u want is to go 45 knots in 20 knots wind, all you need is a butter flat and proper wind. I know where I live it's illegal to create sand bars or tidal basins by hand something about the environment and sand pipers or something, but you might be able to do it where you live check your local laws of course, but if it's legal you can just rent a back hoe, dig a long trench behind the beach and get some nasty speed runs in.