AFTER THE AIRPLANE WAS IN POSITION FOR TAKEOFF FROM THE LAKE, THE WIND DIRECTION CHANGED SO THE PILOT REPOSITIONED THE AIRPLANE TO THE OPPOSITE END OF THE LAKE. THE PILOT SAID THAT THE WIND WAS CHANGING FAIRLY ERRATICALLY. JUST AFTER GETTING AIRBORNE, AND WHILE STILL OVER THE LAKE, THE AIRPLANE STOPPED CLIMBING THEN COLLIDED WITH THE SHORELINE. THE PILOT AND PASSENGER SAID THEY THOUGHT THE AIRPLANE STOPPED CLIMBING BECAUSE THE WIND EITHER CHANGED OR STOPPED BLOWING.