On September 21, 2004, at 0840 central daylight time, an amateur-built Kenny Mariner-MF Boat airplane, N744PK, piloted by a private pilot, was substantially damaged during landing on runway 22 (4,996 feet by 75 feet, asphalt) at Eagle River Union Airport (EGV), Eagle River, Wisconsin. The aircraft struck the left wingtip on the ground prior to touchdown and came to rest about 275 feet southeast of the runway, near the center taxiway. The local flight was conducted under 14 CFR Part 91 without a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot sustained serious injuries. The local flight departed EGV approximately 0835. In his written statement, the pilot reported that control problems were evident after takeoff. He stated that he climbed out to 300 feet above ground level and the nose started "swaying side to side." He decided to return for landing at that time and entered a left-hand traffic pattern. The pilot reportedly reduced engine power and began a descent for landing on base leg. He stated that the nose was "still pitching and yaw[ing] back and forth." The wings did not want to stay level, according to the pilot. He noted the final approach was into the wind with some "side gust." On final approach, about 8 feet above the ground, wind conditions caused the left wing to hit the ground and the airplane spun around. The airplane came to rest about 275 feet southeast of runway 22. The EGV airport manager reported that he witnessed portions of the flight and the accident. He stated the airplane departed runway 22 about 0835. He reported that during takeoff the airplane porpoised twice before it started climbing. The airplane subsequently departed to the south. This witness stated he noticed the airplane again on what appeared to be a downwind traffic pattern leg for runway 13. He noted that "the aircraft looked like it was having control problems and could not stay in coordinated flight. It looked like every time he attempted to make a left turn the airplane would skid to the right." The witness reported the airplane set-up for a landing on runway 22. During the landing the aircraft was "very uncoordinated" and started to porpoise 4 or 5 times above the runway. The witness stated the engine power accelerated, then the left wing tip struck the ground and the aircraft crashed. An FAA inspector conducted a post-accident examination of the wreckage. Flight control continuity was confirmed. No defects associated with a pre-impact failure were observed. The pilot reported that this was the first flight of the experimental amateur-built airplane since it had been re-built. The pilot bought the aircraft in August 2003 after it had been damaged in a prior accident. He completed the restoration himself. He noted that taxi testing prior to the first flight did not reveal any problems and that ground control was "good." Federal Aviation Administration records indicate the airplane was issued an experimental airworthiness certificate on August 19, 2004. The airplane was registered to the accident pilot on April 5, 2004. No previous registration or airworthiness data was on file. The pilot reported 168 hours flight time in airplanes and approximately 800 hours in ultralights. He did not indicate any flight time within the previous 90 days. He noted that his most recent flight review was in 1992. He was issued a third-class airman medical certificate on August 7, 2003.