I started a Gliding club, Edensoaring in Cumbria, UK. That was 2007. They still use 'Skyrope' supplied by Skylaunch on their winch. I think it is three stranded high density polyethylene or polypropylene, 10 or 12 mm, but worth asking Mike Groves at Skylaunch. I have my own) (SKY)rope for expedition auto=towing (UKMSG) . Excellent value at approximately 450 dollars for 1000m (3300ft). In club use it does 1000 launches - ON GRASS - before replacement. Easy to splice.