On April 28, 1999, at 1357 eastern daylight time, a Shempf-Hirth Mini-Nimbus Glider, N100GG, collided with a fence one-quarter mile north of the Seminole Lake Glider Port, in Clermont, Florida. The glider was operated by the pilot under the provisions of Title 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed for the local flight. The commercial pilot received minor injuries and the glider sustained substantial damage. The flight originated in Clermont, Florida, at an unspecified time. According to the pilot, the glider was released from the tow plane at an altitude of 1600 feet. After release from the tow plane, the pilot began to search for thermal pockets. Failing to find a thermal, the pilot elected to return to the to the airport. The pilot stated that he encountered downdrafts which increased his rate of descent to approximately 1000 feet per minute. Realizing that there was not sufficient altitude to return to the airport safely, the pilot elected to make an emergency landing in a nearby field. The glider subsequently collided with a barbed wire fence during the emergency landing, substantially damaging the glider. The glider sustained damage to both wings and a broken canopy. No mechanical problems with the glider were reported by the pilot.