The airplane was substantially damaged during an aborted takeoff from a lake. The pilot stated, "The airplane seemed to have an abnormally long takeoff roll. It just did not seem right. I tried to adjust the pitch of the airplane to find the 'sweet spot' on the step. Slight nose up did not help and relaxing back pressure did not help either. I then decided to raise the right float out of the water to reduce drag. The airplane lifted off the water what appeared to be normal at first. But while I was accelerating and slowly climbing I felt a slight shimmying even though we were now off the water. I decided to abort the takeoff because I still had plenty of water left to land on ahead of me. ...We appeared to touch down on the left float first. Once the right float contacted the water the plane immediately yawed hard to the right and the airplane rolled fast to the left and spun." Water conditions at the time of the accident were reported by the pilot as calm. An examination of the wreckage revealed no pre-impact anomalies.