THE PLT PRPTD THAT AFTER MAKING A SEA LANDING NEAR RASPBERRY STRAIT, THE WIND VELOCITY INCREASED TO AN ESTIMATED 30 KTS WITH GUSTS TO 45 KTS. HE ELECTED TO TAKE OFF TOWARD THE WEST FOR THE RETURN FLT. HE SAID THAT AT ABOUT 100 FT ABOVE THE WATER, THE ACFT ROLLED ABRUPTLY TO THE RIGHT & ITS NOSE PITCHED DOWNWARD. HE CORRECTED WITH FULL POWER & OPPOSITE AILERON, BUT THE ACFT CONTACTED THE WATER BEFORE HE COULD RECOVER. DRG IMPACT, THE 2 FRONT COMPARTMENTS OF THE RIGHT FLOAT RUPTURED & THE RIGHT FLOAT STRUT FAILED. SUBSEQUENTLY, THE RIGHT FLOAT SANK & THE ACFT ROLLED OVER IN THE WATER.