The pilot reported he was repositioning his floatplane from a land based airport to a seaplane base. The takeoff was performed using a dolly, towed by a pickup truck with a 60-foot rope. He stated the tow vehicle accelerated to flying speed; however, he prematurely rotated. The airplane did not have enough airspeed for the pilot to be able to maintain control. He climbed to an altitude of approximately 60 feet, stalled the airplane, and subsequently impacted the ground. The airplane received substantial damage to the wings, and firewall. The recorded wind at a nearby weather station, located three miles west of the accident airport, about the time of the accident, was variable at 5 knots. The pilot reported that the engine was operating properly and that there were no preimpact mechanical failures or malfunctions.