N1544

The pilot of a float-equipped airplane reported that he was attempting to takeoff from a river, in the same direction as the 3 to 5-knot current, with a 5-knot tailwind. During the takeoff run, as the airplane neared a bend in the river, it encountered a 15 to 20-knot quartering tailwind gust. He said that the airplane lost rudder authority due to the wind gust, and he was unable to steer around the river bend. The airplane subsequently struck the riverbank and came to rest upright. During the impact, the left wing sustained substantial damage. The pilot reported no preimpact mechanical malfunctions with the airplane.