According to one source,[REF] the wind gradient is not significant for sailboats when the wind is over 6 knots (because a wind speed of 10 knots at the surface corresponds to 15 knots at 300 meters, so the change in speed is negligible over the height of a sailboat's mast).
In kitesurfing, the wind gradient is even more important, because the power kite is flown on 20-30m lines,[REF] and the kitesurfer can use the kite to jump off the water, bringing the kite to even greater heights above the sea surface.