The pilot flew to Sheepscot Lake to test and monitor the oil pressure gauge that he had just installed. During a high speed taxi test toward the northeast, the pilot said the wind lifted the left wing and dropped the right wing into the water, which caused the aircraft to nose over. The front spreader bar on the floats broke, and the propeller struck the right float and it filled with water. Wind at an airport 15 miles away was from 350 degrees at 10 knots. The pilot reported that there were no mechanical deficiencies with the airplane.