Stuck rappel ropes - use brains, then brawn
You’re pulling the ropes after a rappel, on the ground and dreaming of that post climb pizza and malted beverage, and . . . “#$%^(*&^&%!!!”, the rope is stuck! What are your options? Before you try the advanced (and scary) maneuver of ascending the ropes to free them, try everything you can from below first. There’s two basic approaches: finesse and brute strength. Here’s a few tricks:
Examine the situation before taking any action. Some stuck ropes come free with finesse, some with brute strength. Generally, try finesse first, as pulling hard too early can make a bad situation worse. Pulling hard can lodge it further in a crack, damage your rope on a sharp edge, and possibly pull down rocks. That's why it's the second choice.
If you’re on the ground, try walking back from the cliff or far to one side and pulling from a different angle.
Sneaky Finesse “Flick” Trick: If you suspect the rope might be stuck in a crack or around a horn or something like that, try this Crafty Rope Trick (CRT): Clove hitch the rope to the end of a stick, trekking pole, ice axe, etc, the longer the better. This gives your rope “flick” a larger diameter and can be a lot more effective in freeing it from a small obstruction, If it’s just hung up on a small knob, this often does the trick.
Rubber band trick: You and your partner grab opposite ends of the ropes and pull, hard. One of you keeps the “pull” pressure on, while the other suddenly releases her end. The “rubber band” effect of one end of your dynamic rope “springing” upwards often will get a stubborn rope moving. This also works with a Grigri.
Brute force trick: After you try the above with no luck, time for the muscle. Tie a foot loop and stand/jump on it. One or more people can put the rope through a prusik loop or belay device, jump upwards and lock off on the rope, adding full or multiple body weight. (If you’re off the ground, be sure you’re safely anchored for this.) The next step beyond this is to maybe build a 3:1 mechanical advantage system to try to apply some serious force to the rope.
If it doesn’t come loose after this, you may be faced with one of the scariest situations in climbing, reascending a stuck rappel rope. Hopefully you’re never in this situation, it’s gonna suck. If you still have both ends of the rope, this is a lot safer, because you know the rope is still running through your anchor. Put a couple of prusiks on both strands and get busy.
If you have a Grigri, it might be faster to use that and a foot sling to ascend the rope, provided you fix the other strand to the lower anchor. Learn how to do that here.
If you only have one end of the rope, you’ve hopefully done the 3:1 pull and it still hasn’t come loose. That can give you a little peace of mind that your bodyweight carefully ascending the rope is probably not going to pull it off either. There are various ways to safeguard this. Here’s one: Tie in to the bottom end of the rope, and build an anchor set for an upward pull. Ascend the rope with a prusik and place gear as you can, clipping the rope below your prusik. If the upper stuck section comes free, you take a leader fall onto your prusik and your highest piece of gear. (This approach assumes you can place gear.)
But it’s still going to suck. Good luck.
Of course, preventing the problem in the first place is far preferable to solving it later. Here are some tips to avoid getting your rope stuck.
If you’re doing a two rope rappel, be aware of potential obstacles near your anchor where the knot can get stuck. Use this Crafty Rope Trick (CRT ) to move the knot past the obstruction.
Before you do your pull, carefully look at the terrain above you and decide which strand you should pull to keep the falling rope away from potential obstacles. (if there is an obstacle on the right as you look up, pull the left strand to hopefully keep the rope away from it as it falls.)
If you're doing a double rope rappel, try to plan the previous step from above. Look down the route. If you see an obstacle on the rappeller’s right looking down, then consider pulling the knot on rappeller’s left. Doing this will hopefully help the rope drop away from the obstacle.
If you have a short rappel and a long rope, considering pulling some of the rope through the anchor before the last person rappels.
Before the last person heads down, the lower person should do a test pull by moving the rope side to side, and see that it moves freely. (Yes, this step can be difficult if the upper person has pre-rigged their rappel, which is about the only downside to pre-rigging.)
If the cliff is steep, giving your rope a flick through the anchors right as the top passes through can help send the end further out into space.
If the cliff is lower angle, it might work better to NOT flick the rope, and let it slither down under its own weight. Doing this minimizes making large rope loops that may want to catch on rock features.
In general, it's better to do more short rappels than fewer longer rappels if you’re in terrain (trees, shrubs, blocky alpine rock, vertical cracks) where the chances of a stuck rope are high.