How to tie the Autoblock Knot.
THE AUTOBLOCK KNOT is a quick and easy-to-tie friction hitch commonly used to back up rappels. The autoblock is often made using either a factory-made or temporary loop which grips in either direction and can slide freely over the rope during a controlled descent. Most climbers now rappel with an autoblock hitch below the device, clipped to a leg loop with a locking carabiner. This allows both hands to hold the rope below the device, providing extra redundancy in the rappel. Always use an autoblock knot on the rope as a safety backup when rappelling. Remember, though, that a friction hitch such as the autoiblock will be disengaged if it gets stuck against the rappel device. As an added measure of safety, if the climber must hang from the device and a hitch for any period of time, a "blocker knot" should be tied below the hitch. An overhand knot tie on the bight works well. This will ensure that should something unexpected happen, the climber will not fall to the ground.
Scroll to see Animated Autoblock Knot below the illustration and tying instructions.
- Wrap your Autoblock Hitch cord four or five times around the rappel ropes. Use a thin cord such as 5mm or 6mm static cordage. Use up most of the cord on the wraps. The more wraps that you use, the more friction generated.
- Then clip both ends of the cord into the locking carabiner on your harness leg loop. Lock the carabiner so the cord can’t come undone. Finally, arrange all the wraps so they’re neat and not crossed.