On October 15, 1996, at 1653 hours Pacific daylight time, a Beech S35, N5642K, owned and operated by the pilot, experienced a total loss of engine power on final approach to runway 30 at the Palo Alto, California, airport. The pilot made a forced landing, and the airplane touched down hard in a shallow marsh area of the San Francisco Bay. The airplane was substantially damaged, and the private pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The personal flight originated from Thermal, California, at 1415. The pilot reported that prior to taking off he had calculated that the airplane contained 60 gallons of fuel in its tanks, and the flight would last about 2.75 hours. During the flight he transferred all of the fuel from the tip tanks into the main tanks, and alternated using fuel from the main tanks. The pilot additionally reported that approaching Palo Alto, he repositioned the fuel selector toward the fullest tank. The airplane was equipped with 4 fuel tanks. The two tip tanks each contained a maximum capacity of 15 gallons of fuel. The two main tanks each contained a maximum capacity of 40 gallons (37 usable gallons). The Federal Aviation Administration (FAA) coordinator verbally reported that an examination of the airplane and surrounding marshland did not reveal evidence of any oil or fuel leakage from the airplane. The airplane was recovered and its fuel tanks were found intact. The quantity of fuel observed in the left wing tip tank and the left main tank was 0.25 and 11.0 gallons, respectively. The quantity of fuel observed in the right wing tip tank and the right main tank was 0.75 and 0.50 gallons, respectively. Under the direction of the FAA, a representative from Teledyne Continental Motors examined the engine. No evidence of preimpact mechanical malfunction was found. An external fuel tank was then plumbed to the aircraft. The representative reported that the engine was started and it "ran normally with good throttle response . . . ."