On November 24, 2005, about 1245 central standard time, a Mooney M20F, N52DB, incurred minor damage during a forced landing after takeoff from Lake Barkley State Park Airport (1M9), Cadiz, Kentucky. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight, which was conducted under 14 CFR Part 91. The pilot reported that the flight originated at Hopkinsville-Christian County Airport (HVC), Hopkinsville, Kentucky about 1130. Following taxi and a run up of the engine, the pilot departed using the right fuel tank, which was "just below half full." Shortly thereafter, and upon leveling the airplane at 2,500 feet, he switched the fuel selector and began to operate from the left fuel tank, which "showed half full." After some sightseeing, the pilot proceeded to Lake Barkley Airport where he performed 5 touch-and-go landings on runway 2, then departed for some more sightseeing. Shortly thereafter the pilot elected to return to perform additional landings. After 3 touch-and-go landings, and during the turn from the crosswind leg of the traffic pattern to the downwind leg, the engine lost power. When asked to further explain, the pilot reported that while in the climb he noticed that the airplane's performance seemed to decrease, and that he had to lower the nose to maintain airspeed. He could not recall any of the engine instrument indications, or changing sounds of the engine, but did remember that the propeller continued to rotate. During the descent the pilot made a distress call, increased the mixture, propeller, and throttle controls to the full forward position, and attempted an engine restart using the starter. He could not recall if he had switched fuel tanks. The pilot subsequently ditched the airplane into Lake Barkley. The pilot estimated that the total elapsed time between when he departed and when the engine lost power was about 1 hour and 20 minutes. The airplane was equipped with an aftermarket fuel bladder system, which was installed on December 20, 2002. Since that date the airplane had accumulated 9 hours of flight time. The airplane's most recent annual inspection was completed on January 19, 2005. The airplane was recovered from the lake on and examined by Federal Aviation Administration (FAA) inspectors. The right fuel tank contained a mixture of fluid consisting of about 1/2 fuel, and 1/2 water. The left fuel tank was completely filled with water. Examination of the fuel strainer revealed a small amount of debris. A functional check of the fuel system was conducted utilizing components of the fuel system forward of the fuel pump, and equal fuel flow was observed from all fuel injector nozzles. Examination of the both the left and right fuel bladders revealed a "significant" amount of silicone type sealant was present. The sealant was found around the access panels, and free inside the fuel bladder. The inspectors also observed deformation of the bladder access panel gaskets, indicative of over-torqued access panel fasteners. According to the mechanic who installed the fuel bladders in the airplane, and completed the most recent annual inspection, "I only used the parts and materials called out in the installation procedures provided by the STC holder," and he "would never use silicone on any aircraft fuel system." The weather reported at Campbell Army Airfield (HOP), Fort Campbell, Kentucky, about 22 nautical miles southeast, at 1255, included winds from 310 degrees at 11 knots, few clouds at 3,000 feet, scattered clouds at 25,000 feet, 7 statute miles visibility, temperature 50 degrees Fahrenheit, dewpoint 13 degrees Fahrenheit, and an altimeter setting of 29.85 inches of mercury.