PVT PLT MADE AN OFF ARPT FORCED LNDG AT NIGHT AFTER THE ENG QUIT DUE TO FUEL STARVATION.

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THE PLANNED FLT WAS FROM PROVO TO ST. GEORGE AND BACK. THE ACFT OPS MANUAL INDICATES FUEL BURN AT 6.1 GPH. CALCULATIONS WERE BASED ON THIS CONSUMPTION. THE OUTBOUND LEG FROM PROVO TO ST. GEORGE (209 NM) TOOK 2 HRS AND 25 MINS WITH APPROX 10 GALS OF FUEL REMAINING. THE PLANE WAS REFUELED AND SINCE WE WERE CONCERNED ABOUT OUR GROSS WT AND HAD PICK UP 2 BOXES OF CHKS WEIGHING APPROX 20-25 LBS WE HELD BACK 3 GALS OF FUEL TAKING ON 12.3 GALS. UPON PREFLT INSPECTION THE L WING WAS OVERFLOWING AND THE R WING FUEL COULD BE TOUCHED WITH THE FINGER. THE RETURN FLT WAS INITIATED WAS INITIATED LEAVING ST. GEORGE. APPROX 160 NM INTO THE FLT FUEL GAUGES INDICATED R TANK EMPTY AND L TANK JUST UNDER 1/2 APPROX 45 MI FROM DEST ARPT. I FELT THERE WAS SUFFICIENT FUEL TO COMPLETE THE FLT BASED UPON FUEL GAUGES. ALTERNATE ARPTS WITH FUEL WERE SIMILAR IN DISTANCE AT THIS TIME BASED UPON MY LOCATION. PROVO ARPT WAS IN SIGHT AND RWY LIGHTS WERE ACTIVATED AND I HAD ANNOUNCED A STRAIGHT IN APCH FOR RWY 36 WHEN THE ENG BEGAN TO SPUTTER APPROX 3-5 MI OFF RWY. MY ALT AT THAT TIME WAS 8000 FT. SINCE THERE IS APPROX 3- 4 MI OF WATER IN FRONT OF RWY 36 AND UNCERTAIN THAT GLIDE WOULD BE SUFFICIENT TO MAKE THE ARPT OR THE SPANISH FORT ARPT WHOSE RWY LIGHTS WE ALSO ACTIVATED AND BEING FAMILIAR WITH THE AREA IT WAS DETERMINED TO LAND THE PLANE OFF FIELD IN A FARMERS PASTURE OR ALONG THE SHORE LINE. CORRECT EMER PROCS WERE FOLLOWED AND THE ACFT WAS LANDED SAFELY WITH NO DAMAGE OR INJURY TO EITHER MY SON OR MYSELF OR THE ACFT. IT WAS LATER DETERMINED BY THE FBO MECH THAT THE PROP WHICH HAD STOPPED IN THE VERT POS MAY HAVE BEEN SLIGHTLY BENT WHEN HITTING A BALE OF HAY ON LNDG. THE FBO SPOKE TO THE FAA AND ADVISED THEM THAT THE PLANE WOULD BE FUELED AND FLOWN BACK TO THE ARPT WHICH WAS DONE THE FOLLOWING DAY. CONTRIBUTING FACTORS WERE: 1) HEAD WINDS STRONGER THAN ANTICIPATED AND FAILURE TO OBTAIN WINDS ALOFT FROM A WX BRIEFER RELYING ONLY ON AWOS INFO. 2) FUEL BURN 6.8-7 GALS PER HR NOT 6.1.3. R WING FUEL NOT COMPLETELY FULL TO COMPENSATE FOR BAGGAGE WT. I AM CERTAINLY BLESSED AND FORTUNATE THAT THERE WERE NO INJURIES AND FEEL THIS EXPERIENCE WILL MAKE ME A BETTER; SAFER AND EDUCATED PLT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE HAD BEEN REEXAMINED BY THE FAA AFTER THE CONCLUSION OF THEIR INVESTIGATION. HE NOW REALIZES THAT NOT ONLY THE FUEL GAUGES CANNOT BE RELIED UPON; BUT THAT THE FUEL CONSUMPTION HAS TO BE COMPUTED AT A HIGHER MORE CONSERVATIVE RATE IN ORDER TO ASSUME THAT THE FLT TIME IS COMPUTED LESS THAN EXPECTED RATHER THAN OPTIMUM!