SETTING THE RAPPEL
Tie the ropes together so the lead line runs through the anchor, with the knot on the same side of the anchor as the tag line; you should be pulling the thin rope. This allows the knot to act as a slight backup, pulling against the anchor on the thicker lead line. A variety of knots exist for tying the ropes together. Though some are stronger than the flat overhand (aka the EDK), these knots tend to get stuck more easily.
“I recommend the flat overhand, as it is strong enough and allows for less likelihood of getting snagged while pulling,” says American Mountain Guides Association (AMGA) Technical Director Dale Remsberg. Make sure there are tails of at least 12 inches, no strands are crossed, and the knot is secured by pulling each strand tight before using it.