The pilot obtained a preflight weather briefing and filed an IFR flight plan for the 30 minute flight from Catalina Island to the mainland at Long Beach, California. According to the airport manager at the private uncontrolled airport, the pilot stated to him that he had an IFR clearance on file, but he might go VFR on runway 4. The pilot then taxied out to runway 22 and called on the UNICOM ready for departure. The manager gave the pilot the altimeter setting and wind then the aircraft departed. The manager stated that the weather at the time was sky obscured with an indefinite ceiling. He said the visibility for runway 22 was .25 of a mile while the visibility for runway 4 was 1 mile. The pilot never opened his flight plan. The wreckage was located about an hour later by a motorist about one half mile northwest of the airport and about 100 feet below the runway elevation. The wreckage path was measured to be about 358 degrees magnetic. Ground scar measurements indicated that the airplane was in a right 10 degree banked turn in a slight nose down attitude at impact.