UKC

Why do N.Americans use two locking krabs on the end of a top rope anchor?

In the UK, one is the norm.

This instructor uses THREE.

The action is @ 3:20

youtube.com/watch?v=-mXPDDhuaSQ&

In reply to JimBot:

They weigh more.

In reply to JimBot:

look like wiregates to me, likely back to back

In reply to JimBot:

1. because they sometimes snap
2. because people think that using 2 reduces the friction - it doesn't
3. because, as in this video they are not using lockers, but snap gates

In reply to JimBot:

My SPA instructor said he was converted to using two because it reduces the angle of the rope running through them so wears the rope less quickly. Obviously it's also redundancy.

In reply to JimBot:

Not sure where you picked up 1 being the norm - duff info as far as I'm concerned.

2 is the principle of redundancy.

Always two (identical if possible) screwgates on a fixed top rope climb placed back to back

Same for fixed abseils.

You will often see two quickdraws placed back to back on sport climbs where 2nd wants to lead on clips in or do the route on a top route, as it saves the anchors. Re-thread for lower off only.

In reply to JimBot:

Weird. I have no idea why you'd use any number of snaplinks for this.

Amongst UK instructors that I know, some use a single screwgate to pass the climbing rope through and some use two, generally back-to-back. The thinking is that it would take a lot more effort to break the latter system. Whether there is a real danger of a freaked-out kid opening a locked krab (or it opening itself) is open to debate, but personally I see no harm in adding an extra krab if I've got plenty - If I'm working I do!

On balance I'd say that amongst instructors 2 is the norm, but maybe recreational top-ropers are more likely to use one. Still beats 3 snaps!

In reply to JimBot:

I use two purely for the reason that it's hard for an child client to undo and even that is probably me just being overly paranoid. I don't see the need to use snapgates in any quantity for this purpose.

In reply to JimBot:

The answer is much more interesting than our UKC experts have identified. Using a long rope over the edge like the guy is doing with single karabiner it tends to fall on it´s side and the rope rubs or under load jams, use three (or more) and the karabiners sit at right angles to the rock. I though everyone knew this already

In reply to jimtitt:


I didn't - but straight off to a crag to test. Learn something every day.

In reply to JimBot:

Apologies in advance....

http://st.hzcdn.com/fimgs/60f197830432d6e2_7954-w233-h233-b1-p10--beach-sty...

In reply to jimtitt:

can't say I've ever had a rope rub excessively or jam running bottom rope sessions using less than 3 krabs on the belay.

In reply to David Coley:



Use ovals like he did.

In reply to higherclimbingwales:


As Dave wrote, you can learn something every day. Possibly you don´t run many bottom-roping sessions at Joshua Tree.

In reply to jimtitt:

I have run a lot of top rope sessions, although not at Joshua Tree... I have never had a rope jam because of using one krab, not even close.

Nor have I ever had anyone feel the need to start undoing a krab. I use two if I have enough, to be a big kinder on the rope, but I'm completely happy with one gravity loaded krab that's not on edges etc.

In reply to jezb1:




I did, once. My wife's brother, a novice. I think it might have been because he was unclipping draws as he went, so thought "best unclip/undo everything". I ended up in a panic, screaming as he undid the screw gate at the top.....

In reply to jezb1:

Due to the rounded nature of the top at JTree it´s almost inevitable that the rope and the karabiner WILL be lying on the rock. The use of multiple karabiners to avoid this is described on at least one climbing gear companiy´s website, Singing Rock if I remember correctly.

In reply to jimtitt:

Don't doubt you Jim!

In reply to David Coley:

"What the hell are you doing?!?!?!"

Not your normal group session type thing though...

In reply to JimBot:

I read an accident report in an American website about a guy who broke his back top roping a WI pitch when the single locker he had the rope running through undid and opened.

He lived to tell the tale and reckoned that since they were doing the same route all morning over the course of ups and downs the gate unscrewed and then in a fall the rope unclipped.

In reply to berna:



"Safety in numbers "

If it can happen, it will happen some day.

Its just less likely with a back up.

In reply to 98%monkey:



You don't back the rope up, do you, though? If that principle makes sense as a whole, why don't you top-rope on two ropes?

It's all about risk. A krab failing when top-roping is really very unlikely.

I do agree if there's a chance the krab will rub its gate on something, though.

In reply to David Coley:
I did have a joke with a friend about doing that (unclipping the top anchor) when he did his first second. Fortunately he wasn't stupid enough; there are people I wouldn't even think about doing that with. And I did watch him *very* carefully, and just as he unclipped the last quickdraw reminded him it was a joke.

Not so much the top anchor, though, but that a novice might end up unclipping themselves is a good reason to tie rather than clip into their harness.

In reply to Neil Williams:


My SPA assessor told me he had seen a scared child unclip from a outdoor toprope and hide on a ledge (not on his session, BTW)... (PS details of this story may be slightly misremembered)

In reply to Neil Williams:

For what it is worth, I never top rope through a single screw gate. I normally use either a twist lock, or a screw gate backed up with a quick draw. I would never attach a haul bag to a rope with a single screw gate either. Screw gates come undone all the time if the rope is in motion or the system to jostled about.

And it is possible for a screw gate to fail:

http://www.coldmountainkit.com/knowledge/articles/401-pembroke-being-rescue...

In reply to David Coley:

It's also possible for the rope to fail. Do you back that up when top-roping?

In reply to Neil Williams:


Sometimes

Petzl recommend using two independent systems when self lining.

Double rope technique is always a good idea when sharp rock / rope slashing / rockfall is possible.

The rope is also the most often replaced and checked over piece of climbing gear.
You should check both the sheath and core for damage or wear, that is some redundancy for starters.
I had one very scary moment when a borrowed rope's sheath split open over the top krab on a climbing wall, I kissed the core when I was safely back on the deck.

I back up everything where practical, It does not take long, even in an Alpine environment, in fact it may speed things up because you need to be slightly less cautious. My older and wiser friends never complain.

In reply to Neil Williams:


No. Nor do I backup a twist lock. The problem is with screw gates, as I stated. These regularly come undone on me if ropes move over them.

In reply to Neil Williams:
There have been many cases of failed krabs and cases of krabs behaving unexpectedly (ie opening). A top rope may be in use for an extended period and the there may be people climbing who have entrusted their safety to the person fixing the rope.

Ropes rarely fail in normal circumstances (though knots may) and exhibit clear signs of wear and tear where the internal structure of a krab is usually unknown. The krab is part of system which may fail in several ways not possible in a rope (no gate in a rope for instance) so why not reduce the chance of a single point of failure when it is easy so to do and where not doing so might put someone or a series of someones less experienced at risk?

I'd always use a backup with my own kids so why not with anyone else?

no backup may be fine between consenting (ie equally experienced) adults

In reply to JimBot:

Considering most of the time the piece below you is what's keeping you from a groundfall/life endangering whipper - why do we not use lockers on every gear placement/bolt? Sliding down a runout slab, or taking a near factor 2 fall onto a bolt - just 1 nut lifting out, or quickdraw twisting off away.

I think you have to assess each scenario and risk manage for the situation (and your disposition), but three snapgates seems like a lot. I guess I just like simplicity and a barstock autolocker just seems more aesthetically pleasing to me, less faff at the anchor, especially when you're not using a cordalette.

In reply to David Coley:


Having got the hang of twist locks, I have pretty much stopped buying screwgates. I would be happy, however, using a Belaymaster on a top rope anchor or for clipping in (as the plastic clip stops the screwgate unscrewing).

The UIAA have issued an advisory against clipping in (rather than tying in) with a single screwgate. I can't remember if this was due to an accident or not.

In reply to Jamie B:




AFAIC real dangers: I've seen both.

The required procedure with the companies I work for is twin screw gates, back-to-back, screwed up downwards. The spontaneous unscrewing happened twice last summer, on slabby terrain (no possibility of hanging the pulley point free of rock). Much discussion ensued as to likely causes, but no conclusions were reached, just instructors scratching their heads and saying "that shouldn't happen".

We once had a child (ADHD as I remember) refusing to weight the rope for a lower, and then attempting to undo the top crabs in order to escape upwards.

In reply to JimBot:

One of the peculiar things about climbing technique is that people often don't adapt their practices to the actual situation at hand. Since minimal quick solutions are appropriate on big climbs, many people apply the same rationale to all situations, for example low-key top-roping, where neither time spent setting up nor weight of equipment involved are of any consequence.

This means that risks that most climbers would find totally appropriate on a long route might well, in a fully rational world, be deemed excessive in a mellow top-rope situation. I think a single screw gate at the anchor is a good example. Every experienced climber I know has had a screw-gate come open on them at least once in some situation, so the potential for such an incident is vastly, enormously greater than a top-rope breaking. To somehow equate these probabilities by citing the non-redundancy of a single rope as an argument for single screw gates is absurd. Moreover, the screw gate in these situations is almost always in a location where it cannot be viewed, so that if anything does go wrong it is almost guaranteed to go unnoticed.

I do think that in the US, at least on the online forums, the notion of redundancy is sometimes taken to silly extremes. Some people think you can shout "redundancy!" and that by itself justifies whatever nonsensical over-complication you are advocating. So saying a single screw-gate is not redundant is not, by itself, an argument with any weight.

That said, given that screw gates can and have come undone, given that if they do the problem won't be noticed, I think the real question is why in the world wouldn't you use two carabiners in a top-roping situation? I can only imagine some utterly misplaced appeal to speed and efficiency, and even that is pretty lame---how long does it take to snap on a second carabiner? And what exactly is the downside of doing so?

In reply to bpmclimb:


We do tend to tie rather than clip on our Scout walls to avoid that possibility, and when you've tied the 20th fig-8-with-stopper in a session you tend to be able to do them quite quickly! But undoing the top anchor...maybe better to use a maillon or ring (edit: on a fixed wall)?

In reply to rgold:

Even if the screwgate does manage to come fully undone, you would still need to be either phenomenonally unluckybor exceedingly incompetent in your rigging for the rope to come unclipped.

In the countless millions of toprope climbs that are done every year how many accidents are attributed to the use of a single screwgate?

In reply to timjones:

Some would argue that because there is no real penalty in using two, if the answer is "one accident or more" then two should be used. While I only use one, I can see where they are coming from.

In reply to Neil Williams:


I can see the thought process behind using two, but I have yet to rig a climb where I'm not comfortable using just the one. It's good to be aware of the option but not often necessary to use when careful rigging usually negates the need.

In reply to timjones:

How does "careful rigging" stop a freaked-out kid from opening a krab?

In reply to Jamie B:


I'd suggest that if you are managing the session well then you don't wind up with a "freaked-out kid" at the krab.

Manage the risk early rather than having to deal with it when it's too late. A kid who can undo one krab can also undo two krabs.

In reply to timjones:


I have no idea what the probabilities actually are; I'm sure they are miniscule. But I do know for sure that single lockers used to connect a climbing rope to a harness have come completely unclipped. Assuming the competence of the rigger, we are still left with being "phenomenally unlucky."

But a word about competence. Any one who has been reading climbing news know about a considerable number of accidents happening to very competent climbers, accidents that happened because of inattention or complacency or just plain oversight. Sometimes highly competent people mess up, and arguably the most likely to mess up are the ones who proclaim that they are immune to error. Installing a second carabiner is an admission that we are not perfect and that just because we can't see how something could go wrong doesn't mean that something can't go wrong.

Issues like this go beyond this particular example. How to deal with what one judges to be exceedingly unlikely events? Personally, I won't use up time, equipment, and complications---when these things matter---in order to guard against something that is so unlikely as to seem hypothetical. But in a situation like toproping, where it costs me absolutely nothing to add a second screwgate, why not eliminate even hypothetical failure points? Why does this even elucidate responses and garner "dislikes?"

I know personally of a few accidents in which the party could be said to have been "phenomenally unlucky." We accept such risks as part of the game. But we don't have to apply a uniform standard of risk tolerance to every sub-genre of the game, and certain situations are reasonably treated with more caution than others.

There is another aspect to this, which I think of as a question of moral responsibility. If you arrived at a stance and found your partner had constructed a totally inadequate anchor, you'd probably have some words with them about that. The climbers involved in top-roping are often people who have no ability to judge the effectiveness of the rigging their lives absolutely depend on. They have (in some cases without justification) placed all their trust in the rigger. A young woman on her first day of climbing died in my local area because the person who rigged her toprope was either incompetent or phenomenally unlucky. I wouldn't want to be the person telling loved ones that a death was phenomenally unlucky, not when that death could have been prevented by something as utterly trivial as snapping an second carabiner into the anchor power point.

In reply to timjones:

So when you said "careful rigging" you actually meant "careful session management"? Clear as mud...

In reply to rgold:
As an addendum to my post above, consider the following report from Accidents in North American Mountaineering, which indicates the potential faiures we've been discussing are not simply hypothetical.

RAPPEL FAILURE, CARABINER UNCLIPPED, INADEQUATE BELAY Colorado, Eldorado Canyon State Park, Supremacy

On July 11,1994, a climber was teaching a person (37) how to rappel. Several successful rappels were completed before the carabiner/sling system failed and the victim fell 20 feet to the ground. She sustained a dislocated and compound fracture of the right ankle. (Source: Steve Muelhauser, Park Ranger)

Analysis

Somehow, the carabiner linking the rappel rope to the sling system at the anchor point came unclipped. Though it was a locking carabiner, it was not locked or was inadvertently unlocked, according to the report.

It is common practice to belay beginning rappellers, and many guides prefer to use two carabiners at the anchor point, especially when multiple rappels are to be done. Another unfortunate factor at climbing areas that are easily accessible is that anchor systems have mysteriously come undone and falling objects such as rocks and beer bottles come from nowhere. (Source: Jed Williamson)

In reply to berna:


Just thought I'd repost this from further up in the thread to juxtapose it with the AAC accident report I just posted.

Here is a link to what was probably the accident report.

http://publications.americanalpineclub.org/articles/13201213476/Fall-on-Ice...

Note that the rope coming out of a single screwgate carabiner is one of the possible causes but not the only one.

In reply to Jamie B:


No that not what i meant. The careful rigging comment was in reply to the suggestion that the krab may come undone. It was you that then introduced the idea that a freaked out climber might try to undo the krab for some reason.

Are you sure it's not your thinking that is a little muddy

In reply to JimBot:

One solution to the possibility of scared clients unlocking screwgates is to use an 8 descender to connect the bottom rope to the rigging rope instead. It's marginally more effort to thread the dynamic rope through as you have to start at one end rather than clip in the middle, but it is then impossible either for it do undo itself accidentally or for the climber to remove. I tend to be carrying them anyway, because a day that starts with group top-roping usually ends with abseiling.

In reply to rgold:
great posts, but then I'm biased as you've more eloquently restated some of my own views on "why not" and also the fact that you are rigging a system for people less able to judge for themselves, therefore err in favour of safety.

Why would you depend, and make other people's safety depend, on a single fallible component (lots of reports over the years of krabs breaking as well as just opening unexpectedly) when there is zero penalty in setting redundancy - a decent rope as you say cannot be compared in terms of reliability with a single krab.

Far different level of care needed from the appropriate economy we'd hope to practice on a multi pitch route.


Single point of failure - Avoid if reasonably possible! Engineers know that, hopefully!

In reply to timjones:

Arguing with you is like trying to nail an eel to a wall.

In reply to JimBot:

Has there ever been a recorded incident of a single top rope screw gate krab failing?

I've never heard f one but I'd be interested to learn.

In reply to Trangia:


Possibly, if you read all the posts above.

But, does it really matter ?

Stack the odds in your favour when you can, unless you want to be the first statistic.

In reply to Rick Graham:

Always top rope with 2 half ropes threaded through independent Carabiners and anchors and tied seperately to novice harness. Then have two independent belayers with independent belay devices. You can never be too careful.

In reply to Orgsm:

Yes but then if one of them fails you'll be trusting your life to just one half-rope. You're gonna die!

In reply to Jamie B:


Who's arguing?

I thought we were discussing climbing

In reply to john arran:

Quick get me a third rope!

In reply to Orgsm:


Isn't that pretty much the EEC health and safety directive we were threatened with a few years ago?

In reply to David Coley:


I remember seeing a rope rub a screw gate and undo it when I was climbing indoors once.cant remember exactly how but my it did scare me a bit.

In reply to Trangia:

"Has there ever been a recorded incident of a single top rope screw gate krab failing?"

I'd put it another way - Has anyone Ever Died as the result of a component of an anchor system failing where it was set up to allow a single point of failure?

Bearing in mind the context (possible Repeated use by novice/inexperienced people in the care of the creator of the anchor) then there is the question of duty of care. Have those top roping consented to climb when there are risks which can be vitiated or mitigated by those in charge? If the inexperienced knew that the directors of the session were not taking any Reasonable Steps to reduce risks would they still be happy to consent to something organised by them?

As I say, setting up for my own kids I know I'd not willingly involve a SPF in an anchor so I wouldn't with any one else who had a lesser level of experience than mine.

In reply to wercat:


The answer is yes.

The person who asked this question asked it just after I posted a recorded incident. (I posted a second one---pretty tragic---which might or might not be a screw gate problem.) These two incidents were found by a very cursory googling effort which would not have picked up anything from Europe, so it is entirely possible that more might be found by a less desultory search.

I and quite a few other posters have argued that the answer to this question does not provide a good basis for the decision to add a second screwgate to a top-rope anchor, but for those who demand an accident first, at least one has happened.

Perhaps it is worth adding that there is very little humans are worse at than estimating probabilities. What seems "phenomenally unlikely" may or may not be all that impossible; our ability to judge such things is poor to non-existent. Given that, virtually by definition, unlikely things happen, one ought to deal with the "expected value" consideration, in which the perhaps minuscule probability is multiplied by the enormous tragic cost of the consequences, resulting in an expectation that is not at all tiny and is worth guarding against in spite of the probabiity's small size.

Here's a final thought: everyone knows that screwgates come undone in circumstances that aren't always understood, and that such events are not phenomenally unlikely---as I said before almost every experienced climber I know has had one such episode. So it isn't exceptionally unlikely that you could end up top-roping on an carabiner without any kind of locked gate. So I'd say that's the real comfort question: are you comfortable toproping through a single non-locking carabiner, because it isn't phenomenally unlikely that this could be your situation if there is but a single screwgate in the anchor.

In reply to rgold:

I admire your calm tenacity in patient replies.

But TBH this effort may as well be spent in doubling up your own belays.

In reply to JimBot:

For top ropes I'd always at the minimum connect two slings (equalized) to two screwgates for independence even if it's from one bomber anchor (e.g. a large tree).

I think the chances of the crab failing is very low, but the chances of other failures are much higher e.g:
- Crab in the wrong place in the sling, not really connected
- Anchor badly set/failing
- Snap gate getting undone
- Screw gate not being screwed shut and being undone
etc...