On July 4, 2014, at 1405 central daylight time, a Slaughter CH601-HDS ultralight airplane, N4263, impacted Lake Palestine, Texas, near Frankston, Texas, while maneuvering at low altitude. The pilot was seriously injured and the passenger received minor injuries. The airplane was substantially damaged. The airplane was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed. The flight originated from Mineola Airport (3F9), Mineola, Texas, and was en route to Aero Estates Airpark (T25), Frankston, Texas. According to statements provided to FAA Inspectors and law enforcement officers, the pilot and his son were returning to T25 after attending a fly-in at 3F9. The son said that during their descent to T25, the pilot spotted a boat and began to follow it at low altitude. The pilot then made a steep turn and stalled the airplane, lost control, and impacted the water. The pilot and passenger were rescued by nearby boaters. The wreckage remained in the lake and was not available for examination. Neither occupant indicated there were any system malfunctions with the airplane prior to the accident and indicated fuel exhaustion did not occur.