Two ScheMPP-Hirth gliders, N184N & N6482, were being flown in a cross-country contest along a triangular course. The course started at Minden, NV and went to Schurz, NV and Bridgeport, CA, then back to Minden. The pilots of both gliders had participated in contests for over 10 years and were good friends. Witnesses observed the two gliders flying close to each other along the route near the Bridgeport Reservoir. The pilot of N184N said that he saw N6482 about 200 feet above him while both were in a thermal. He said that N6482 left the thermal at about 15,500 feet. He (N184N) made another turn in the thermal, then left it to continue toward Bridgeport. The pilot of N184N said that when he left the thermal, he did not see N6482 until sometime later, just a fraction of a second before impact. He reported that N6482 converged from N184N's 8 o'clock position. After impact, N6482 entered a descent and crashed in a hilly wooded area. The left wing tip of N184N separated and the canopy was damaged, but the pilot was able to land at Bridgeport.