Note - This post discusses techniques and methods used in vertical rope work. If you do them wrong, you could die. Always practice vertical rope techniques under the supervision of an experienced climber, and ideally in a progression: from flat ground, to staircase, to vertical close to the ground before you ever try them in a real climbing situation.
Sometimes, a fast moving climbing team can come to a screeching halt when making a rappel (or a few of them.) The logistics of setting up and completing a rap seems to gobble up the clock like no other part of climbing, especially if you have a group of newer climbers. Add to this approaching darkness, a building storm or the horror of missing happy hour, and reasons to rap quickly become even more pressing.
The next time you’re stuck in a crowd at a rap station, try this trick:
Feed the rope through the rap anchor as for a normal rap.
If it’s a sling anchor, clip a locking carabiner to the shelf (photo above). If the anchor is twin chains, clip a locking carabiner to each bolt hanger or to a link of chain.
Tie one strand of rope into the locker with a clove hitch. (Or, use two lockers on two bolts as shown below)
You now have two fixed single lines, allowing one climber to rappel while another is rigging their rope (I call this being in the "on deck circle" like in baseball) The second person should be ready to begin at the moment the climber ahead of them is on the ground or at the next anchor.
This can really speed up your downward progress, because there's no downtime waiting for anyone to rig. Someone should be moving down the rope at all times.
The last climber unties the clove hitches (which are used because they are fairly easy to untie even after being loaded), cleans the carabiner(s), and raps normally.
Note: Be sure that all party members are comfortable rapping on a single strand of rope. If the rap rope is free hanging, and/or the rope is skinny or wet, climbers may descend faster than they are used to. If this happens, climbers can use various techniques for adding friction to a rappel - read about a few methods at this tip.
Another method - “pre-rig” with an extended rappel
Another approach to expediting a group rappel is to have everyone use an extended rappel, and do what's called a “pre-rig”. This means that everyone in your group has their rappel device on a shoulder length runner, and they are all attached to the rope at one time. By extending the rappel, the climbers waiting at the top will not be yanked around when the rope is under tension.
Doing this expedites the rappel, because the moment the first person gets to the ground or the next anchor and creates a little slack in the rope, the next person can immediately head down. This is the same idea as the fixed single strands Illustrated above, but allows each person to rap on double strands of rope, which gives a little more friction and is probably more comfortable for beginners. Having a pre-rig speeds up the entire process, because once again there should be someone moving down the rope pretty much constantly.
The number of people in your party, and the size of the ledge around the rappel anchor will dictate the method you use. Lots of people, and maybe a small stance? Use The “fix separate strands” method mentioned at the top. Small team, and perhaps a larger ledge around the anchor? Then use the pre-rig method described here.
Here's a few more photos showing how to set up fixed rappel lines on a chain and sling anchor
1 - Thread the rope normally for a rappel.
2 - Clip a locking carabiner to each bolt.
Clove hitch each strand of rope to the lockers. Voila, each strand is now fixed separately. The last person unties the cloves, cleans the carabiners, and raps normally.
On a sling anchor, thread the rope for a normal rappel, and clip a locking carabiner to the shelf.
Then, tie a clove hitch (or if a real knot gives you a warm fuzzy feeling, a figure 8 on a bight or butterfly) and clip it to the locking carabiner. Both strands of rope are now fixed.