We only had a landrover, but we also had a parachute, and as the lightest at the gliding school on that day (too windy for flying) I was the first one to try it. I did soar as soon as we moved forward but the tow rope was tied to the shoulder straps... I now know that I can hold my breath for at least 4 minutes. It didn't half give me a right good squeeze. We learned from that and the next one was towed off using a cut down seat harness. Great days as an ATC cadet.