Advanced rappel
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These are canyoneering techniques that are not commonly used. However, in a pinch they come in handy.
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[edit] Simulrapping
This is an anchorless system where two canyoneers rappel against each other on opposite ends of a rope. The rope is drapped over an arch or a very solid object. The two canyoneers must weight and unwieght the rope together. Should one start before the other, the second will be pulled forward, over the top of the arch. If one unclips before the other, the second will fall. Injuries have occured when a partner "forgot" to stay on the rope. Be careful out there.
- See Simul-rap on the Advanced Canyoneering Anchors page for techniques to limit rope marks from simulrapping.
Simulrapping can also be done off conventional anchors. After setting the rope for retrieval, the unblocked side should be clipped off to the anchor (for all but the last pair). Two rappellers rap simultaneously, each on a single strand. The two rappers should stay close together, so they do not knock rocks on each other. This method can be used to help speed descents or for enhancing pictures.
For the last pair down, the heavier person raps off the block, and the lighter person raps off the heavier. This is, once again, fraught with the possibility of misadventure.
- See Petzl page for details and pictures.
[edit] Locking Off
There are a number of ways to tie off a rappel mid-descent. This may be useful to adjust equipment, take a high-risk picture or set up a prussik to ascend or pass a knot.
- Leg wrap - Wrap the rope around a leg a number of times. This is simple. Note that movement in the leg can result in laxity in the brake line and a little descent.
- A tube device can be locked off by pinching the brake strand on the side of the device with the left hand. This should hold the rappel. Then tuck the brake strand through the belay loop and lock it off with a mule hitch. Lock this loop with a carabiner clipped to your harness so the weight of the rope doesn't pull the mule hitch loose. Practice close to the ground first! See discussion.
- On a Figure 8
[edit] Rappel backup
When passing a knot, on a tricky rappel, a thin single-line rappel, an overhung rappel, or a rappel with ledges that may require untangling the rope, it may be useful to set an auto-backup system. However, if you really need a belay, use a top-rope or fireman belay! Many rappel backup systems exist. To one degree or another they all are fairly marginal in that: A. they must be tied exactly right or they will not work; B. they must be let go of, or they will not work; C. when they do work, they can be difficult to escape from afterward.
Many canyoneers feel rappel backups are marginal at best and should rarely be used. The prusik knot 'above' the rappel device has been generally discarded as the most dangerous way of doing it because once set under load, it is almost impossible to release - use an autoblock. Many experienced canyoneers feel that the time and effort put into installing and using the autoblock are better spent not screwing up the rappel in the first place. Gary Storrick describes specific examples of how this system can fail. These should be reviewed before using this system. This technique is described here more as a tool to carry in the toolbox, than as a recommended technique for regular use.
Extreme caution should be used applying an auto-backup on a wet rappel. Should the rappeller become trapped in a hydraulic, the backup may prevent escape! Also, while a Bachman or prusik knot is easy to tie, it can be difficult to release unless body weight is off it. This can be done by locking off the rappel device, wrapping the rope around a foot and then standing on this loop. Even so, getting back on rappel can be tricky.
- A simple Bachman or prusik above the rappel device.
- Tie a Bachman or prusik on a loop to the anchor line above the rappel device (the Bachman is preferred as it is easier to release once weighted).
- Clip the Bachman/prusik loop to a second locking carabiner on the harness.
- On rappel the guide hand slides the Bachman/prusik down the anchor line as rope feeds through the rappel device.
- Should the rappeller loose control and remember to let go of the Bachman/prusik, the Bachman/prusik may grab the rope just might arrest the fall.
- One can also set a system below the rappel device. In general, this system is preferable, although the geometry has to be almost perfect to prevent the auto-block from hitting the rappel device. This can be done with either cord or webbing.
See also:
[edit] Passing a Knot on Rappel
This is an advanced technique. It is tricky at best and the cost of failure is, well, extreme. Thankfully canyoneers rarely need to pass a knot on rappel. However, there are a few very long rappels, which require tying two ropes together to negotiate. Bringing a rope long enough for the longest rappel is advised, so that passing a knot is not necessary.
In general, this is the sort of thing that should be learned from someone with skill and should be practiced a few feet off the ground before one is required to utilize this skill a rope length or so off the deck. It may be a useful skill should the main rope become damaged.
Alternatively, one can avoid the "passing the knot" problem with a lower and rap technique.
- Rappeller clips in below the knot on a rappel device.
- Belayer clips in above the knot, on the far side of the anchor, and lowers rappeller to the end of the first rope.
- Rappeller then completes rappel on the second rope using their own device.
- Last canyoneer down has to deal with the knot, but no one else does.
See also:
[edit] Changing Abrasion Point
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