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Tech Tip: Question Minimizing risk with(out) contingency anchors

Discussion in 'Tech Tips and Gear' started by Tricam, Sep 3, 2020.

  1. Tricam

    Tricam

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    Reading through accident reports, these things seem to involved in a fair bit of death and destruction. There seem to be two major classes of failures:
    • the block was improperly rigged (inexperience and complexity making it difficult to inspect)
    • the "block" has no mechanical locking mechanism and is going to fail in certain circumstances (ex: jester)
    So given the above and the assumption that most people don't want to kill themselves or others, a couple questions:
    1. Why are these things even used outside of class C canyons? The only two cases that I can think of are for beginner groups or when you can't see the bottom. For beginners, I would hope that they have been prepared enough before being put in a canyon that lowering events are rare, and convert to lower (or even cut and lower) would be sufficient. When you cannot see the bottom, it would seem that a double rope rappel or a biner block, toss, and adjust would be nearly as efficient but significantly safer due to lower complexity of the system.
    2. Why are device-specific releasable blocks popular, when the munter-mule-overhand is sufficient? I would hope that anyone leading a group would already be familiar with the MMO as a backup in case of a lost rappel device. More importantly, others with experience should be able to inspect an MMO. Even the basic figure 8 block has tons of variations (many of which are non-locking, and thus insecure in certain situations) that make inspection tricky. I wouldn't trust my life to something that I couldn't inspect without a backup.
    Last edited: Sep 3, 2020
    Scott Patterson likes this.
  2. Canyonero

    Canyonero

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    First be sure you're not confusing blocks with contingency anchors. An anchor can be both, but all blocks are not contingency anchors, particularly the most common one, the biner block (which is usually implicated in accidents involving rapping on the wrong side of the rope.)

    Second, they're used to be able to lower a rappeler in the event of something happening- rope not long enough to reach bottom, hair/shirt caught in device, person freaks out etc.

    Third, convert to lower takes forever compared to a contingency anchor. Lowering events are rare with a well-trained group, but I've certainly done them before.

    Fourth, cut to lower sucks because then you have to replace the gear at a minimum, but may not even have the gear needed to finish the canyon.

    Fifth, I prefer the MMO, but a contingency 8 is admittedly a lot faster to set up and really not that hard to inspect.
    Tricam likes this.
  3. ratagonia

    ratagonia

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    I'm with you, but I reach different conclusions.

    1. Seems like a lot of accidents occur when people use techniques they are not proficient with. (Yes, kind of a "de facto" fallacy here). Kinda like the guy who lost control on the last rap in Heaps and came in hot. Broke his back (in a minor way). This was his FIRST single-line rappel.

    2. Any technique one is not familiar with is "complex". There are techniques that are complex even after you are proficient with them, but all things under discussion here do not fit in that category - all these things are simple once understood and practiced.

    3. It is good to be practiced in techniques that you will NEED rarely, so that when you need them, you can do them right.

    Tom
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  4. Tricam

    Tricam

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    Ah, good point. I was referring to contingency anchors, but used the term block, which is inaccurate and does not cover all types of contingency anchors.
  5. Tricam

    Tricam

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    With an experienced group, when have you found the need to lower? Was this anticipated where you didn't know the rappel height and decided this was the most efficient way to handle it, or have you run into "emergency" lower type situations that individuals couldn't handle on their own? If the former, is there a reason you choose this over other available methods?
  6. Tricam

    Tricam

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    When you inspect someone else's contingency 8, what do you do if they use a different variation than one you are most familiar with? I guess this also applies if they use some other unfamiliar device for the contingency rigging?

    The principals are the same, but it would take some time inspect something novel. Do you trace the rope path and look for adequate friction before a lock of some sort? Add a backup biner or knot block? Or just trust it?

    I enjoy learning, comparing, and testing these different systems, but I'm struggle to imagine"what if" scenario that includes "you have device X to rig an anchor, but no locking carabiners for an MMO".
  7. Tricam

    Tricam

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    Good point, and most likely the variable that has the highest correlation to accidents.

    The other edge of this is that a lot of accidents occur by experienced people that have become complacent in their technique. Rappelling off the ends of ropes kills several climbers each year, and I've caught myself about to clip into the tail end of two EDK joined ropes at least once... :/
  8. Tricam

    Tricam

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    Fully agreed. Although I may have come the conclusion that I won't be using these outside of class C conditions, I want to be confident that I could deploy one efficiently with whatever funky shape of metal someone may be passing as a rappel device these days :D
  9. Canyonero

    Canyonero

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    At a minimum, start a conversation about it. At a maximum, re-rig it the way you like it. They can put it back their way when they rappel. And of course the ever popular "pull really hard on it and see if it seems to be holding."
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  10. Canyonero

    Canyonero

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    Well, the usual other available method is "just throw an extra 10-20 feet down there" and then you end up with 30 feet too much instead of 15 feet too little. But on rare occasion, "I'm not sure the rope is down, let's put this on a contingency so you can lower me in case it isn't." I confess most of those I canyoneer with have never been stuck in a way they couldn't get unstuck. You know, stuff like getting your bladder hose (not that bladder hose) caught under the rope at the lip.
    Yellow Dart and Tricam like this.
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