SMT FLYING OVERWATER HAS FUEL STARVATION; DITCHES.

Narrative

WE HAD LANDED AT PROVIDENIYA ARPT FOR DEP CUSTOMS AND TO ADD FUEL FOR FLT TO GAMBELL TO CLR CUSTOMS; THEN ON TO NOME. I CHKED THE FUEL GAUGES AND NOTED THE AUX TANKS INDICATED 1/4 FULL (10 GALLONS EACH). WE ADDED 15 GALLONS TO EACH MAIN TANK; BRINGING THE GAUGES TO JUST ABOVE 1/2 FULL (APPROX 30 GALLONS IN EACH). A TOTAL OF 80 GALLONS. APPROX 2 HRS 15 MINS AT NORMAL CRUISE; ESTIMATED TIME FOR THE FLT WOULD BE 1 HR 30 MINS. IT TOOK 25 MINS TO GAMBELL WHERE I NOTED MAIN FUEL GAUGES SHOWED 3/8 -- APPROX 20 GALLONS IN EACH MAIN; GIVING ABOUT 60 GALLONS TOTAL. WHEN AIRBORNE; I ESTIMATED WINDS NNE AT 20 KTS; SO REQUESTED WINDS ALOFT AT 6000 FT AND 9000 FT. NOME RPTED LIGHT AND VARIABLE SO I REQUESTED IFR CLRNC TO 7000 FT AND ESTIMATED 1 HR 15 MINS ENRTE. DURING CLB I USED ABOUT 80 PERCENT PWR AND LEANED TO EGT RED LINE. AT 7000 FT I REDUCED PWR TO 2200 RPM; 26 INCHES MANIFOLD PRESSURE; AND LEANED TO RED LINE AND DME SHOWED 150 KTS. I SWITCHED TO AUX TANK ON R ENG AND EXPECTED ABOUT 30 MINS; BUT IN 10 MINS THE ENG QUIT. I SWITCHED BACK TO THE MAIN TANK AND IN ABOUT 15 MINS ALL FUEL WAS EXHAUSTED ON R ENG. I CONSIDERED XFEED BUT DECIDED TO FEATHER THE PROP AND HEAD TO NEAREST LAND -- SLEDGE ISLAND. WE WERE ABOUT 60 DME OUT OF NOME ON 240 DEG RADIAL. I CALLED ZAN AND TOLD THEM OUR PROB AND INTENTIONS. I SWITCHED L ENG TO AUX AND IT LASTED ABOUT 10 MINS. I DECIDED TO CONTINUE IN A CRUISE PWR DSCNT ON THE L ENG AND AT 4500 FT ALL FUEL WAS EXHAUSTED. WE LANDED IN THE WATER ABOUT 2 MI SW OF SLEDGE ISLAND. THE CAUSE: THE FUEL GAUGES DID NOT GIVE RELIABLE INFO AT LOW LEVELS. THE FUEL LEVEL CANNOT BE OBSERVED BELOW ABOUT 33 GALLONS IN THE MAINS AND 15 IN THE AUX. SO I RELIED ON FUEL GAUGE INDICATIONS WHICH HAD BEEN QUITE RELIABLE ON HIGHER FUEL LEVELS. SOME WAY OF CHKING FUEL LEVEL VISUALLY WOULD HELP WHEN FUEL IS BELOW THE 1/2 LEVEL INSTEAD OF DEPENDING ON FUEL GAUGES OR TIME FLOWN.