THE BRAZILIAN MANUFACTURED AMPHIBIAN HOMEBUILT KIT AIRPLANE HAD NOT MADE ANY WATER LANDINGS OR TAKEOFFS PRIOR TO ITS ARRIVAL AT THE EAA FLY-IN. IT HAD BEEN PARKED IN A COVE ADJACENT TO A LAKE. SOMETIME DURING THE EVENING AND/OR EARLY MORNING THE FOLLOWING DAY, THE AIRPLANE BECAME PARTIALLY SUBMERGED WHILE MOORED DUE TO ROUGH WEATHER AND WATER. IT WAS BROUGHT CLOSE TO SHORE AND THE WATER REMOVED. PRIOR TO THE FLIGHT WITNESSES OBSERVED THE PILOT AND AN ASSOCIATE PULLING THE AIRPLANE ONTO SHORE BY THE TAILBOOM. DURING THE SECOND DAY OF FLYING, THE EMPENNAGE AND TAILBOOM ASSEMBLY SEPARATED FROM THE FUSELAGE/HULL DURING A DESCENT. POST-CRASH EXAMINATION REVEALED THAT THE TAILBOOM WAS CONSTRUCTED WITH ONLY FOUR OF THE SIX REQUIRED CARBON FIBER LAMINATE PLIES. IN ADDITION, THE STRIPS UTILIZED TO HOLD THE TAILBOOM TOGETHER WERE ALSO MINUS ONE CARBON FIBER LAMINATE PLY. THE TAILBOOM CAME ASSEMBLED FROM THE KIT MANUFACTURER IN BRAZIL.