The pilot stated that he completed a preflight and noted the airplane had 50 minutes worth of fuel. He arranged to have 4 more gallons of fuel added, which brought a total of 9.5 gallons of fuel onboard the airplane. He took a direct heading to Okeechobee after departure, cruising at 3,500 means sea level. The flight distance was about 51nactical miles with about 12 to 18 knots, northeast wind condition, giving an indication of 110 knots. He elected to land on runway 5 and was second to land, following another airplane in the downwind. During final, at about 250 feet above ground level, the airplane had a loss of engine power. He verified the engine controls; however, he had no time for an engine restart at the attitude the airplane was at. He elected to land on the grass prior to the runway. The airplane impacted with a 10 foot wide ditch about 255 feet from the runway's threshold and become airborne again. The nose gear bent and the bottom cowling was damaged before it came to a stop. He exited the airplane after securing the master switch and the magnetos. A gentleman from the airport came over with a tractor and assisted him in towing the airplane into a hanger. As the airplane was towed, he noticed fuel leaking from the airplane. He reached inside the cabin area and turned the fuel selector valve off. This was about 35-40 minutes after the incident occurred. The person who assisted the pilot in recovery of the airplane from the accident site stated to the airport manager that he did not observe any fuel leaking from the airplane during the recovery process. He confirmed with the pilot that the fuel selector valve was in the off position before the airplane was moved. The FAA inspector that conducted the post accident examination of the airplane stated he drained 1.25 gallons of fuel from each wing tank. A total of 2.5 gallons of fuel was collected. The airplane's unusable fuel is 3.5 gallons as noted in the airplane's Type Certificate Data Sheet, 3A19.