The knots are multiple half hitches drawn up tight against
the glider.

Always use a Truckers hitch, IMHO:
http://www.ehow.com/video_2355281_ti...itch-knot.html

What if we don't have a piano?

Then use the harpsichord!

Exactly! Then, tie the other end to the wing tie down point. I've found
that harpsichords rarely move in a hurricane.

Tony V