On May 14, 1995, at 1003 hours Pacific daylight time, a Cessna 177RG, N34938, overran runway 33 after the pilot aborted the takeoff ground roll at Oakland International Airport, Oakland, California. The pilot was beginning an instrument flight rules personal flight to Redding, California. The airplane, registered to and operated by Alameda Aero Club, Alameda, California, was destroyed. The certificated private pilot and two passengers were not injured; one passenger sustained minor injuries and was transported to a hospital and released. Visual meteorological conditions prevailed. The pilot told National Transportation Safety Board investigators in a telephone interview that during the takeoff roll, the engine, " . . . did not sound right . . . " and that the airplane did not accelerate properly. The pilot aborted the takeoff, but he was unable to stop the airplane within the runway environment. The airplane exited the departure end of the runway and collided with a ditch and sank into a marsh filled with 18 to 22 inches of water. The pilot also said that he calculated the airplane weight and balance before departing on the accident flight. According to his calculations, the airplane takeoff weight and center of gravity were within the manufacturer's limits. Safety Board investigators conducted a telephone interview with the passengers. The consensus of the passengers was that the pilot aborted the takeoff when the airplane was between 1/2 and 3/4 distance down the runway. Two of the passengers said the engine sounded normal; the remaining passenger said the engine appeared to momentarily hesitate, but not misfire. A Federal Aviation Administration (FAA) airworthiness inspector from the Oakland Flight Standards District Office inspected the airplane. The inspector reported that he did not find any evidence of any airframe or engine preexisting malfunctions or failures. He also said the spark plugs exhibited normal operating signatures. Besides the occupants, the airplane contained full fuel (about 68 gallons), camping gear, and personal baggage. The pilot filled the fuel tanks by adding 50 gallons of fuel before the flight. Safety Board investigators calculated the airplane weight and balance at the time of the accident. According to the calculations, the airplane weight exceeded the maximum allowable gross weight by 215.7 pounds. (See item 15.03 herein this report for the detailed calculations.)