Damage to the aircraft firewall, propeller and other external structures was reported by the Catalina Airport Assistant Manager subsequent to the aircraft landing at the island. The pilot told the airport manager that while enroute between the mainland and the island his engine quit, and, just before impact with the ocean, he was able to get the engine restarted. The pilot reportedly said that the nose gear hit the water during the event. The pilot, an Italian national, did not report the accident to the FAA, the Safety Board or the FBO where the aircraft was rented and immediately returned to Italy. After the airplane landed, airport employees observed the pilot pour a handful of dirt into the oil filler tube. An FAA airworthiness inspector examined the aircraft. He reported that the tips of both propeller blades were bent symmetrically back at 45 degree angles without leading edge damage or cordwise scratches. The bottom part of the firewall was bent aft and upward crush damage was observed on the bottom of the engine cowl. The entry step was ripped from the aircraft and the lower rotating beacon was found pushed up through the fuselage skin panel. Other external and internal water damage was also noted.