On July 22, 2000, about 1200 Eastern Daylight Time, a homebuilt HP-11-A glider, N586A, was substantially damaged after impacting trees near Dansville, New York. The certificated private pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight conducted under 14 CFR Part 91. According to the pilot, the glider was towed to 1,500 feet, and released. The pilot flew "some" circles looking for lift and found a "weak' thermal at 200 feet. The location of the thermal was west of a ridgeline that ran southwest, about 1 mile east of the Dansville Airport (DSV), Dansville, New York. The glider climbed to 1,000 feet and began to drift from the winds aloft. The pilot attempted to find lift off of the ridgeline, but only encountered sink. The glider began to lose altitude and impacted trees about 2 miles east of DSV. The pilot reported a total flight experience of 2,177 hours, all in gliders. The pilot did not report any mechanical difficulties with the glider. The DSV weather reported at 1154 was, winds from 290 degrees at 7 knots, scattered clouds at 4,600 feet, broken cloud layer at 6,000 feet, and a temperature of 68 degrees Fahrenheit.