On June 10, 2000, at 1055 eastern daylight time (edt), a Truthan Searey, N89PJ, homebuilt seaplane, operated by a private pilot, sustained substantial damage when it flipped over during taxi on the Thorn Apple River, near Grand Rapids, Michigan. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under 14 CFR Part 91. No flight plan was on file. The pilot and passenger on board reported no injuries. The local flight was originating at the time of the accident. In his written statement, the pilot said that he was taxiing north on the Thorn Apple River at approximately 28 knots. He said that the west bank of the river section he was taxiing on was bordered by gradually down-sloping bluffs. When the airplane got past the bluff-section of the river, it "nosed into the water and the aircraft flipped, tail over-the-nose, coming to rest inverted." After the airplane was recovered, the pilot noted damage to the step of the hull. The pilot thought the damage to be consistent with striking a submerged log. A Federal Aviation Administration inspector examined the wreckage when it was recovered from the river. The airplane's right wing and forward struts were bent. The forward fiberglass hull, fore deck, and "turtle" deck were cracked inward. Flight control continuity was confirmed. Examination of the engine, engine controls, and other airplane systems revealed no anomalies. At 1056 edt, the weather reporting station at Kent County International Airport, Grand Rapids, Michigan, 11 miles west of the accident site, reported few clouds at 2000 feet, 9 miles visibility, and winds 210 degrees at 16 knots gusting to 21 knots.