Accident Report - Rigging Failure During a Rappel

[Iceaxe]

[BW123]

__

[bjp]

ATS rigged ala Jester, methinks

Looks equivalent to the Totem version to me.

How I've rigged an eight, but, not sure if other folk do it this way, or, that its Stefan's way

Thanks for the great pictures. However, I still don't think this eight block is "locked". I've colored the rope according to how much tension is on it, for both the clove hitch and your eight block (I'm not sure which way the strands go in your eight block, so I have two versions; they differ only by a half-twist of the final bight):



In the clove hitch, note that a high-tension part of the rope (the diagonal segment) is on top of a lower-tension part of the rope (the vertical segment on the left) -- this is what locks/pins it to the bar. In the eight block, there is no high-tension part on top of a lower-tension part (or rather, there is no low-tension part in between the figure 8 and a high-tension part) -- it is not locked to the figure 8. For this reason, I would put the figure 8 block in the "non-locking" category along with the Joker, Jester, etc, and since I trust the figure 8 block (and it seems like pretty much everyone else does too), I don't think it's reasonable to categorically call the Jester unsafe simply because it doesn't lock. It may or may not be safe for other reasons (such as not providing enough friction), but unless I'm missing something, I take issue with this statement:

I don't see how you can look at this and NOT be scared. There is no mechanism that 'locks' it.

[ratagonia]

I guess we disagree on what it means for something to lock.

As someone said - if you pull on it and it will go to full strength without slipping, it is (de facto) locked.

If you pull on it and at some force it starts to slip, it is (de facto) NOT locked.

Figure8 block - Locked (pretty sure). Because rope crosses rope, and the way the rope crosses rope.

Tom

p.s. Nice coloring job...

[bjp]

I guess we disagree on what it means for something to lock.

As someone said - if you pull on it and it will go to full strength without slipping, it is (de facto) locked.

If you pull on it and at some force it starts to slip, it is (de facto) NOT locked.

Hmm, yes, we have different definitions. The key difference is that a rigging could be Tom-locked with one size of rope and not-Tom-locked with another size of rope. If a rigging is Ben-locked with one size of rope, it should be Ben-locked for all sizes of rope. So when we observe that the Jester is not Tom-locked with new, thin rope, that doesn't really tell us much about whether the Jester is Tom-locked with thicker, standard rope. In fact, "full strength" is relative; perhaps the Jester IS Tom-locked for new, thin rope if the system includes a sand trap ;)

Figure8 block - Locked (pretty sure).

Interesting; I'm inclined to think it's not Tom-locked under some circumstances. I'll test and report.

Because rope crosses rope, and the way the rope crosses rope.

Surely this isn't the reason it's locked. I can easily create a Tom-locked anchor where rope never crosses rope -- just put 6 normally-rigged figure 8's on a rope, one after another.

[ratagonia]

Hmm, yes, we have different definitions. The key difference is that a rigging could be Tom-locked with one size of rope and not-Tom-locked with another size of rope. If a rigging is Ben-locked with one size of rope, it should be Ben-locked for all sizes of rope. So when we observe that the Jester is not Tom-locked with new, thin rope, that doesn't really tell us much about whether the Jester is Tom-locked with thicker, standard rope. In fact, "full strength" is relative; perhaps the Jester IS Tom-locked for new, thin rope if the system includes a sand trap ;)

Interesting; I'm inclined to think it's not Tom-locked under some circumstances. I'll test and report.

Surely this isn't the reason it's locked. I can easily create a Tom-locked anchor where rope never crosses rope -- just put 6 normally-rigged figure 8's on a rope, one after another.

"Full Strength"

"Going to full strength" in testing means that the rope breaks. If your anchor or test fixture breaks, that means you did a poor job of setting up the test. If I break my telephone pole anchor, I am in big trouble.

A system is much more useful if it "locks" independent of rope size. Knowing that the Jester works for some ropes but not for others is not real useful to ME - I want my rigging things to work with all (reasonable) sizes of rope. Wet or dry, new or well-used, full moon or new moon.

I think we are talking past each other, BJP. Perhaps some actual testing, rather than more talking would be a good idea, and would clarify meaning. No, tom-locked should be independent of rope size. Yes, it is possible to make something that locks without rope crossing rope, but that would be the difficult way. Most systems that "lock" have rope crossing rope.

"just put 6 normally-rigged figure 8's on a rope, one after another"

Our discussion has progressed to the "extension to absurdity" - suggesting that more back and forth is unlikely to be fruitful.

Tom

[deagol]

..... I am hard pressed to see the ANY difference between the 2 setups....

(pics)

One thing I noticed is the rapide in Andre's version is through the top biner and perpendicular to it, while the rapide & top biner are parallel in Rich's pic. Not sure what effect this would have on the system.

Disclaimer: I have used the Totem in several ways, but never as a jester.

...A system is much more useful if it "locks" independent of rope size. ...

I have used the Totem in ascending mode with two different diameters of rope and overall I love the Totem. However, to my dismay, the Totem does slip when using the 8.3 MM rope. I thought I could use it for this use on all my ropes, but after noticing this, I am thinking I may need a device for that purpose.

[Brian in SLC]

Looks equivalent to the Totem version to me.

Isn't the "Jester" a method for the "Totem"? I ask out of ignorance...

Thanks for the great pictures. However, I still don't think this eight block is "locked". I've colored the rope according to how much tension is on it

As the kids say (or, Kenny on South Park), thats "hella cool!"

I think mine's on the bottom, as, there's a half twist finish on my loop.

I get my full weight on the rappel strand, and, static on that, I just set there. Then, I can undo and lower easily whilst my full weight is on the rope. I like it. Also, for back up, out of the photo to the left, there's a clove hitch on a 'biner for back up.

Thanks for the "color" commentary!

[ratagonia]

Isn't the "Jester" a method for the "Totem"? I ask out of ignorance...

The "Jester" is a rigging technology, that could be implemented with any piece of metal with appropriate geometry.

Tom

[bjp]

Could you post a picture of the Joker you are using?

Joker:

[rcwild]

Seems Andre should have taken more than one photo and/or taken better notes and/or paid more attention during the course. I told his class, just like I tell every other class, that the Jester provides the core rigging system for a variety of applications. It can be used for lowering, single-rope contingency, double-rope contingency, creeping the rope with depth gauge, rigging plate for top rope belay, rigging plate for converting contingency to haul, etc. etc. etc.

I told Andre's class, just like I have told every other class, that the Jester, (correctly) rigged only in "core" mode slipped when I tested it in single-rope contingency mode with narrower diameter ropes (8mm Canyon Pro DS). Until someone is sure how it will behave with their particular rope, it should be either minded or tied off -- when used for single-rope contingency. Even if you are confident your rope won't slip in single-rope contingency mode, it only takes an extra 10 seconds to tie it off, so why not?

Needless to say (at least for those who understand the techniques) it is not necessary to tie off if it is rigged for creeping the rope or double-rope contingency.

After making all of those points, the students practiced with it using 8.9-9.2mm ropes. Their concerns went from "will it be enough friction" to "there is too much friction to lower". I demonstrated the normal-friction lowering mode and another low-friction lowering mode.

The Totem WORKS for rappelling and rigging with ropes from 8mm to 10mm. The Jester rigging system WORKS with ropes from 8mm to 10mm. Like virtually all devices, it is rigged differently to accommodate its diameter range. Kinda like how you need to rig a figure eight differently with various diameters, how you need to rig an ATC differently with various diameters, etc.

The Jester WORKS when it is used correctly (which includes minding it or tying it off when rigged in single-rope contingency mode, especially with narrow diameter ropes). It might not work when it is used incorrectly.

Stone Knot works when it is used correctly. It might not when it is used incorrectly. MaxxiPad works when it is used correctly. Might not when it is used incorrectly. Water version of MaxxiPad works when it is used correctly. Might not (did not?) when it is used incorrectly. Figure eight knot works when it is tied correctly. Might not when it is tied incorrectly. Etc. Etc. Etc.

I have been teaching the munter-mule since 1994 and can demonstrate at least 5 common mistakes people make when rigging it. Quite a few people avoid using it because they are not confident with their ability to do it correctly. The Jester is much much simpler to rig than a munter-mule. I can teach anyone the core Jester rigging system in a couple minutes and have never seen anyone get it wrong. Until now.

In future courses I will be showing Andre's photo to point out how improper rigging can cause problems. I will also make it a point to have people use the Jester with 8mm rope to add emphasis to my points about minding or tying off.

I learned the Stein Knoten (Stone Knot) in Austria in 1999 and taught it to Tom several years ago. Surprised to hear that it is anyone's "go-to" rigging. Converting it to lower in 2.X minutes? That's an okay time, unless there is water present and the rappeller in distress can't hold his breath that long. Jester will do everything the Stone Knot will do and much much much more. Lowering takes a couple seconds. In well under one minute I can solve the distressed rappeller's problem without lowering him more than a couple feet. Even converting to haul can be done well under 2.X minutes.

[rcwild]

Joker:

Ben,

Try threading the rope on the right from front to back so the loop is on the front side of the neck on the figure eight. Opposing loops will hold the figure eights in position more securely. Not a big deal most of the time, but on occasion (like when the rigging is pressed up against the rock) it can make a difference.

[rcwild]

One thing I noticed is the rapide in Andre's version is through the top biner and perpendicular to it, while the rapide & top biner are parallel in Rich's pic. Not sure what effect this would have on the system.

Doesn't make any discernible difference in friction.

I have used the Totem in ascending mode with two different diameters of rope and overall I love the Totem. However, to my dismay, the Totem does slip when using the 8.3 MM rope. I thought I could use it for this use on all my ropes, but after noticing this, I am thinking I may need a device for that purpose.

Which ascending system are you using? Stop-n-Go or Plaquette (autoblock).

When the Totem first came out, students were coming up with dozens and dozens of ways to use it. That was cool, but I now teach just a handful of what I consider to be the most beneficial uses. If you know you need to ascend, use ascenders. I only use the Totem in ascending mode if I need to go up and come right back down or visa versa.

[bjp]

A system is much more useful if it "locks" independent of rope size. Knowing that the Jester works for some ropes but not for others is not real useful to ME - I want my rigging things to work with all (reasonable) sizes of rope. Wet or dry, new or well-used, full moon or new moon.

That is a sufficient but not necessary condition for a good system. The figure 8 block does not work (lock) with all sizes of rope, particularly under certain moons (when something gets between the quick link and the figure 8). Yet I still think it's a perfectly good system when used appropriately -- likewise with the Joker, which (almost) never locks. If you don't want to watch the whole video explanation, just check out 2:38 to 3:46:
---
EDIT: I've removed the video because it showed a version of the figure 8 block which does not lock when not pulled against the quick link; Tom's version a few posts below is a better rigging.

For historical purposes, the key portion of the video showed a non-locking figure 8 block jammed against a quicklink using 8.3mm Canyon Fire rope; that configuration locks by squeezing the rope between the figure 8 and quick link. When the figure 8 block is suspended above the quick link so that the figure 8 can't squeeze the rope against the quick link, the rope easily (perhaps 50-70 pounds) pulls through the figure 8 block.
---

To recap:
1) A locking system always must have a strand or component with higher tension/force squeezing a strand with lower tension
2) The figure 8 block's locking mechanism is squeezing a lower-tension strand between the quick link and figure 8
3) This mechanism does not necessarily occur in all riggings of the figure 8 block
4) A system does not need to be locked to supply friction force greater than the breaking strength of the rope
5) Not all systems/situations require that the supplied friction force exceed the breaking strength of the rope
6) The Joker and Jester are both non-locking systems that supply less friction force than the breaking strength of the rope under most circumstances
7) Particularly on the Jester (and probably on the Joker; not yet tested), there are some reasonable rope and rigging combinations where the supplied friction force is not sufficient

Thanks to ag23 for letting everyone know about #7.

[dustinsc]

Like Rich said, moral is block it off. But I would say always, even when using both sides. If the system works as advertised, you should be able to get a biner block or a mule hitch off of it, right? Doesn't matter if your rope is thick. I'm not experienced with these types of riggings, but common sense tells me that if a system is at all dependent on rope size, you should be extraordinarily careful with it.

[hank moon]

Like Rich said, moral is block it off. But I would say always. Doesn't matter if your rope is thick. I'm not experienced with these types of riggings, but common sense tells me that if a system is at all dependent on rope size, you should be extraordinarily careful with it.

Lotsa variables in any system. Rope: diameter, stiffness, state of wear, wet or dry, new or used, dirty, icy, etc. How worn is the friction device(s), and so on.

Question for the Joker/Jester users out there: is there a significant advantage gained by NOT tying off?

[dustinsc]

Lotsa variables in any system. Rope: diameter, stiffness, state of wear, wet or dry, new or used, dirty, icy, etc. How worn is the friction device(s), and so on.

Let me roll it back then. If a system is that dependent on the metal on rope friction, then you should be especially careful. Not that you should ever be lackadaisical with any system....

[Iceaxe]

Lotsa variables in any system. Rope: diameter, stiffness, state of wear, wet or dry, new or used, dirty, icy, etc. How worn is the friction device(s), and so on.

I read that as.... a lot of different ways this system can fail.

Most folks only have one large chip to wager with in the big game of life.... bet yours wisely.

[ratagonia]

That is a sufficient but not necessary condition for a good system. The figure 8 block does not work (lock) with all sizes of rope, particularly under certain moons (when something gets between the quick link and the figure 8). Yet I still think it's a perfectly good system when used appropriately -- likewise with the Joker, which (almost) never locks. If you don't want to watch the whole video explanation, just check out 2:38 to 3:46:

To recap:
1) A locking system always must have a strand or component with higher tension/force squeezing a strand with lower tension
2) The figure 8 block's locking mechanism is squeezing a lower-tension strand between the quick link and figure 8
3) This mechanism does not necessarily occur in all riggings of the figure 8 block
4) A system does not need to be locked to supply friction force greater than the breaking strength of the rope
5) Not all systems/situations require that the supplied friction force exceed the breaking strength of the rope
6) The Joker and Jester are both non-locking systems that supply less friction force than the breaking strength of the rope under most circumstances
7) Particularly on the Jester (and probably on the Joker; not yet tested), there are some reasonable rope and rigging combinations where the supplied friction force is not sufficient

Thanks to ag23 for letting everyone know about #7.

Thank you for your efforts BJP.

However, you make some assertions that I think I can be demonstrate to be false:

"1) A locking system always must have a strand or component with higher tension/force squeezing a strand with lower tension"

Rats! A careful reading notices the phrase "or component" in there, which makes my dis-proof a non-dis-proof. But here it is anyway, the Garda Knot, which has no ropes crossing but still locks even on 3mm cord:

(Pictures 1 and 2 below, if I got them to load in the right order).

"2) The figure 8 block's locking mechanism is squeezing a lower-tension strand between the quick link and figure 8"

Well, I suppose, if you use the NON-LOCKING FIGURE-8-BLOCK, then the only locking mechanism is that. However, why would you use that? With a simple half-twist, you can make a LOCKING FIGURE-8-BLOCK, which seems to have all the bene's of the non-locking version, plus the benefit that it locks, no matter what the cord size.

(LATE ADDITION:
EXCEPT, as Benjamin has pointed out in a separate conversation, it is no longer a contingency anchor because it does not release!

Tom
)

(see the rest of the pictures, below).

I personally do not use Figure-8-blocks, though I suppose I should practice it some so if I canyoneer in Ouray with Brian, I won't be surprised...

======

AND - perhaps you noticed that I did not prove my thesis. Correct. That was not the point. The point was to provide an example of a locking, non-rope-crossing system to refute the claim I THOUGHT you made; and to present a locking version of the Figure-8-block that people might find more secure than the non-locking version that you show.

Tom

[Brian in SLC]

Yeah, Tom, that half twist make a big difference to me.

I'd be good with whatever contingency rig folks want to use, munter/mule, stone, figure eight... I wouldn't be overly psyched to dive onto a jester rig with a 8mm canyon pro rope, though, unless one side is tied off.

Cheers!