The aircraft was cruising just inland of the beach at 1500 feet when the pilot noted smoke, accompanied by a strong burning smell entering the cabin from the lower right hand side air vent. Almost immediately the engine suffered a complete loss of power. The pilot carried out a successful wheels-up forced landing on the beach. A fire which had been burning in the nose wheelwell area had apparently been extinguished by seawater and wet sand during the landing slide. Inspection revealed that chaffing had occurred between an electric cable and hydraulic line situated in the wheelwell. Arcing from the electric cable burnt through the hydraulic line, and hydraulic oil under pressure escaped in a fine spray and was ignited by the arcing. This created a torching effect which was directed at the fuel strainer. The heat caused the fuel in the strainer to boil, developing a vapour lock and disrupting the fuel flow to the engine and causing the subsequent engine failure. The chaffing of the cable on the pipe was in such a location that it would have been difficult to see during normal periodic or pre-flight inspections.