On January 9, 2010, at 1255 eastern standard time, a Stinson 108, N97223, experienced a total loss of engine power during cruise, near Bayport, New York. The private pilot and passenger were not injured and the airplane was substantially damaged during the subsequent forced landing. The flight was operated as a personal flight under the provisions of 14 Code of Federal Regulations Part 91, and no flight plan was filed. Visual meteorological conditions prevailed at the time of the accident. The flight originated from Bayport Aerodrome (23N), Bayport, New York, at 1240. The private pilot stated that during cruise flight at approximately 600 feet, the engine began to run rough. He said that he applied carburetor heat and subsequently the engine cleared up; therefore, he decided to disengage the carburetor heat. When he did this, the engine again began to run rough again and lose power. The engine never regained full power although the pilot re-engaged the carburetor heat. The pilot subsequently made a forced landing on a shoreline and the airplane nosed over. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the airplane landed in water on a shoreline. The airframe was buckled and the airplane nosed over inverted into 3 feet of salt water. The airframe and flight control system components revealed no evidence of preimpact mechanical malfunction. Examination of the engine did not reveal any mechanical malfunctions. Twenty gallons of fuel was defueled from the fuel tanks. The fuel was a mixture of aviation and automotive gasoline. The main fuel gascolator was removed, and debris was discovered in the bottom of the bowl. The carburetor inlet filter was removed and also contained debris. The current ambient temperature was 28 degrees Fahrenheit, with a dew point of 9 degrees Fahrenheit. Review of the icing probability chart revealed the airplane was not flown in conditions conducive to carburetor icing.