The second step to tie an autoblock knot, after wrapping the cord around the rappel ropes, is to clip both ends of the cord into the locking carabiner on your harness leg loop. Then lock the carabiner so the cord can’t come undone from it. Finally, dress the knot by arranging all the wraps so they’re neat and not crossed. Make sure the knot is not tightened or cinched down on the ropes so that it slides easily as you rappel.
Make Sure The Knot Won’t Jam
It’s very important to check the knot before you use it by making sure that the length of cord or sling is not too long after being tied to the rappel ropes. First, check that your autoblock knot cinches onto the rope when it’s weighted. Next, check that the sling is not so long that it will jam in the rappel device when it’s weighted. If you’re using a short sling that is no longer than two feet then it shouldn’t be a problem if your rappel device is attached to your belay loop and the knot is attached to your leg loop. Double check to make sure though. If the sling or cord is too long and it jams in the rappel device then it will lead to all kinds of problems when you’re rappelling. If it is too long, then use a sling on your belay loop to extend the distance that the rappel device is from your harness and the knot.
