With big rappels come added challenges. You can get away with a lot on a rappel that is 100 feet or less, but when you start doing big rappels (think 200 or 300 feet) there are extra considerations. Two of the most important considerations are the need to adjust the amount of friction on your descender while rappelling and the danger of bouncing.
Friction Settings - At the top of a big rappel, there will be a significant pull from the weight of the rope. You may even have a full bottom belay from the weight of the rope and find yourself feeding the rope through your device. However, as you descend the rappel, the amount of rope below you will steadily decrease. This reduction in weight and friction has caught plenty of people off guard and has been the cause of many accidents at the bottom of big rappels. It is crucial on big rappels to have a device that you can add friction while rappelling like a Crittr, Hoodoo, or Sterling ATS (which can all be found in our shop under Descending Devices).
Bouncing - Because there is so much rope involved in big rappels the rope stretch becomes a factor, especially on single-strand rappels. As a result, people often begin to bounce. Differences in friction needs from the top to the bottom also lead to bouncing as people try to change settings to get the friction right. Do everything you can to avoid bouncing. Bouncing has been a huge factor in groups cutting their ropes on big rappels. For example, Egypt 2 slot canyon in Escalante, Utah has been the scene of many core shots due to bouncing on the rope and the sawing effect this has against the sharp black rocks in the sandstone. Consider using rope protection on big rappels and practice smoothly transitioning through friction settings on your device before you go. Also if you rig releasable, you can adjust the rope length after each person finishes the rappel so that wear and tear is not on one single point. A 300-foot canyon rope weighs around 8 to 10 pounds. You can practice with added weight by tying a weight to the bottom of your rappel line at home. Then remove the weight and compare how much friction you need with different amounts of weight pulling below you.
Big rappels can take you to breathtaking spots. Practice at home and consider using a hands-free backup like an auto-block or a Valdotain Tresse (VT Prusik) to back up your rappel.