Petzl Simple and Stop: attachment mailion modification

[Tubo Longo]

I'm not sure - it may have been that incident. When did it happen, and is there a detailed accident report available on-line?

Late 2005 - early 2006: I'll do some research and post them later

Common opinion is that the accident might have been avoided if: 1. the bobbins would have been locked while rigging 2. the brake biner would have been connected to the bobbins's biner instead than to the maillon.

I'm confused by your second point. My understanding is that if you use a separate braking carabiner you should always clip it directly into your maillon - and never into your descender attachment carabiner. Something like this:



As a reference, check out pages 70-72 in "Vertical" (the 3rd, 4th and 5th pages down on this link) - http://www.caves.com/6DESCENT.pdf

Have you been taught different?

Yes and no. The common opinion is, in Europe too, to position the brake biner on the maillon, the way is shown in TSA and Vertical. But is at least a decade (more likely some 15 years) that is well known the possibility that the head of the bobbins MIGHT get into the brake biner in certain situation, i.e. when on rope but with the bobbins not loaded and hanging kinda free and/or slack. If this happen and the caver doesn't realize it BEFORE resuming the rappell (check, check, check...), then is in a free uncontrolled free fall.

The easy solution is to clip the brake biner into the bobbins biner (which btw make kinda unpractical to use a maillon biner for the bobbins, but not a regular oval or delta). Or to buy a Handy brake by Raumer (with a small opening that doesn't allow for the bobbins to fit in) or a Freino.

Unluckily this simple trick is not very well known nor very used. And actually neither Vertical nor the most recent edition of TSA (as far as I remember) mention it.

Cheers -- Renato

[potholer]

Even if a Stop/Bobbin does end up going through the braking krab, wouldn't the tilting just reduce the friction it caused, giving a chance that the user could still descend, if rather more slowly?

I suppose on very thin/fast rope the resulting loss of friction may make it very hard to control descent, but presumably there's a chance of recovery if fraction round the body/leg is applied quickly enough. Possibly some habitual thin-rope users get used to lifting the rope above the braking krab to get maximum friction, rather than pulling the rope behind the body?

I wonder how many near-misses there have been?

I guess a Stop user might be a little more likely to notice the problem, since they'd generally have a hand on/near the Stop whenever commencing descents.

[Tubo Longo]

Even if a Stop/Bobbin does end up going through the braking krab, wouldn't the tilting just reduce the friction it caused, giving a chance that the user could still descend, if rather more slowly?

Sorry, I might have not expressed myself very clearly.
When I talk of the head of the bobbins I mean only the upper part: if we look at the pic posted by NZCaver, we should figure out the bobbins turning more horizontally to the right and entering into the biner OPPOSITE from its attachement point.
If the bobbins would go all the way thru, then we might have only some reduced friction (may be, don't know). But if it's only the upper bollard to fit into the brake biner, then there's no control on the rappell, since the bobbins is stuck middle way into the brake biner.

[potholer]

No - there wasn't a problem with your description - a Stop/Bobbin can only go part-way through the braking krab since the 'up' rope coming out from the left side of the lower bobbin will prevent the descender going completely through.

However, if the descender end up part-way through the braking krab, the effects will be
a) The braking krab won't do anything, since the rope isn't running through it - raising the rope will no longer increase friction unless/until the rope ends up being pulled up against the 'third pin' on the end of the descender.
b) There will be less friction from the descender since the rope now has less contact with the lower and upper cams.
c) *Maybe* the stop function of a Stop won't work (or won't work as well) - I suppose that depends on whether the new rope path still causes the cam to turn as it normally does.

However, the rope does still run round the lower and upper cams of the descender, just with less contact than it normally does due to the descender being tilted.
Therefore friction will be reduced (which might be a particular problem on thin/greasy/fast rope), but the device will still provide some friction, and should still respond to extra friction from gripping the rope with the right hand or wrapping the rope around the body or leg.
On thick/slow rope, the problem might not be very difficult to control.

I may experiment next time I'm somewhere where I can do so safely, with a knot a few metres below me.

[Tubo Longo]

I'm not sure - it may have been that incident. When did it happen, and is there a detailed accident report available on-line?

Late 2005 - early 2006: I'll do some research and post them later

Here I'm. The accident happened on June 18th, 2005 in the Gouffre du Pot2, a pit 319m deep (1047'), located in the higher part of the Vercors plateau in the French Alps, near by Grenoble (some 3 hrs hike to get to).
The caver who died was Gerard Ayad, a well known French explorer, with explorations done around Europe (French, Italy, Spain) and in Mexico.

He was leading a team of 6 cavers and went ahead solo to rig the pit, using a 8mm rope and a Simple with brake biner on the maillon. After having rigged the first 110m (361') of the pit, he stopped to rig a rebelay and to drop the remaining 200m (656') of rope out of the bag and down the pit.
Since at that point he had an extimated weight of about 8kg (some 18 lbs, considering an average weight of 41g/m for an 8mm rope) on its bobbins, he likely did not locked at all the bobbins, since the weight of the rope was actually preventing a rappell without feeding the rope in.
Apparently, as I already wrote (but this is a general guess, since he was alone and nobody witnessed the accident), the bobbins went horizontal (and its head went into the brake biner, without Gerald realizing it) when he stood up to unclip the cowstails from the rebelay and to resume the rappell. He hence went into a free fall.

His body was found on a ledge at -270m (-886'), still attached to the rope, the bobbins bended but threaded, the hands severely burned possibly by an attempt to regain control or, at least, to slow down somehow his fall.
Injuries were consistent with at least a possible hit on the wall before landing on the ledge.

The French Cave Rescue website report only a schedule of the rescue operation and the above details are a summary of several posts (by some of his Italian friends) on the Italian caving discussion list over a span of about a month back then.

[potholer]

Thanks for the information. From the country concerned, I was wondering if thin rope was involved.

Relying on the weight of the rope and not hard-locking does seem quite a gamble, especially when the weight of rope below will tend to cause the problem mentioned.

I suppose even leaving a long cowstail in for pre-descent checking wouldn't be guaranteed to prevent the problem, since if the cowstail ended up loaded after a descender check, a caver might still stand up on a ledge to unclip it, and have the descender pull through the braking krab, though most of the time, most people would usually keep a hand on the down rope even in that situation.

It is a bit ironic that pulling the rope out of the bag presumably in the hope of giving a controllable descent on 8mm could be the cause of the uncontrolled descent.

[Tubo Longo]

Thanks for the information. From the country concerned, I was wondering if thin rope was involved.

You're welcomed: I forgot that an 8mm was involved

Relying on the weight of the rope and not hard-locking does seem quite a gamble, especially when the weight of rope below will tend to cause the problem mentioned.

I agree, but I have seen many explorers doing so. The fact is that, in my experience, when you stand up to unclip the cowstails, then the bobbins ALWAYS tend to turn side way, even when completely locked off.

I suppose even leaving a long cowstail in for pre-descent checking wouldn't be guaranteed to prevent the problem, since if the cowstail ended up loaded after a descender check, a caver might still stand up on a ledge to unclip it, and have the descender pull through the braking krab, though most of the time, most people would usually keep a hand on the down rope even in that situation.

My short cowstails is as long as the bobbins, but still I have seen the bobbins bending on the side thousands of time

It is a bit ironic that pulling the rope out of the bag presumably in the hope of giving a controllable descent on 8mm could be the cause of the uncontrolled descent.

Well, yes. Ironic, sad and tragic

[potholer]

Generally, leaving a long cowstail clipped in until after the descender had been test-loaded successfully would prevent injury from this kind of problem, since the caver would usually be fully loading the descender while unfastening the long cowstail, and so preventing it from tipping significantly under the weight of the rope below.

At least, that's how I use my long cowstail at pitchheads and rebelays - clipped into the lowest possible attachment point (such as the hanging loop of the rope section above a rebelay), and left clipped in until the short cowstail has been removed and my Stop loaded and tested for friction and locking.

In that situation, it's only really where the descender could be unloaded while the long cowstail was being unclipped that the problem could arise at a picthead/rebelay with nasty consequences, and I'd guess that'd be most likely to happen where the long cowstail had become loaded when the caver test-descended too far, requiring them to climb/stand up on ledges, and/or pull up on the knot/loop to detach the cowstail (possibly using both hands in the latter case).

[paul]

No - there wasn't a problem with your description - a Stop/Bobbin can only go part-way through the braking krab since the 'up' rope coming out from the left side of the lower bobbin will prevent the descender going completely through.

However, if the descender end up part-way through the braking krab, the effects will be
a) The braking krab won't do anything, since the rope isn't running through it - raising the rope will no longer increase friction unless/until the rope ends up being pulled up against the 'third pin' on the end of the descender.
b) There will be less friction from the descender since the rope now has less contact with the lower and upper cams.
c) *Maybe* the stop function of a Stop won't work (or won't work as well) - I suppose that depends on whether the new rope path still causes the cam to turn as it normally does.

However, the rope does still run round the lower and upper cams of the descender, just with less contact than it normally does due to the descender being tilted.
Therefore friction will be reduced (which might be a particular problem on thin/greasy/fast rope), but the device will still provide some friction, and should still respond to extra friction from gripping the rope with the right hand or wrapping the rope around the body or leg.
On thick/slow rope, the problem might not be very difficult to control.

I may experiment next time I'm somewhere where I can do so safely, with a knot a few metres below me.

Another factor to consider besides loss in friction - consider the following scenario:

You are abseiling on a pitch with a number of re-belays with another caver is abseiling below you on the other side of a re-belay. Now if a bolt or anchor fails between you and the other caver, you will now have the full weight of the other caver pulling down on your Bobbin-type descender - this could quite easily force the top of the descender into the braking carabiner and cause it to deform or even break.

This is the scenario outlined in "Alpine Caving Techniques" and why the authors recommend using a Raumer "Handy" as it is too narrow to let a descender be forced through.

I have tried one of these with a Petzl Simple and found it a very jerky as the "Handy " easily grabs the rope. A friend who works in a shop selling climbing and caving gear didn't advise using the Freino for caving as since it is made of alloy, the braking part will soon wear through in many caves with grit and dirt on the rope. So, I have stuck to my original steel carabiner for braking.

[potholer]

Would a descender being pulled though the braking crab by a bodyweight on the rope actually be likely to break the descender or the krab?
The static load doesn't seem likely to be a problem, and presumably in the case of a lower rebelay failing, it's likely to be much less than a fall factor 1 applied in most circumstances, which would limit the dynamic load.
The forces would seem likely to be basically in the plane of the descender where you'd thing it was pretty strong, but maybe if one sideplate caught on the krab...?
Mind you, that's all just thinking out loud, and could well be nonsense.

I've heard from a few people that the Handy can give a jerky descent, at least in cases where not much extra friction is required - possibly more useful on thinner/faster ropes where a regular steel braking krab often doesn't give enough extra friction?
I can imagine that for a stereotyped Alpine caver using Bobbins on thin ropes, the ability to stop a descent without huge effort by pulling the rope up into the wedge could be useful, and offset the disadvantage of jerkiness to some extent.

[Tubo Longo]

My guess is there are too many factors to consider to could get a good answer.

Cowstails in the loop It surely an extra safety, like a QAS. Indeed not very used, at least in Italy: the idea is to leave, clipped to the loop, the brake biner as extra safety while passing the rebelay: but then the caver should lock the bobbins and check it out while unclipping the cowstails, to avoid a situation like the one in the accident.

Caver on rope below you Well, the scenario doesn't count in many important factors, like how far away is the upper caver from both the lower caver and the rebelay, what kind of rebelay, etc.
But I don't really think the static weight of the lower caver alone could force the bobbins thru the brake biner, not to speak to deform or even break it: just think how a pick-off ends, with two cavers hanging from one descender. May be the combined dynamic forces resulting from the fall of the lower caver and the rebelay failure could damage (to what extent?) the bobbins, but not surely a static load.
More important, in that scenario, is the fact that the added weight applied to the rope will make impossible to continue the rappell (basically, it will be a huge bottom brake) and so the upper caver will have to changeover and downclimb or, more easily, wait for the lower caver to get to the bottom (or past another rebelay) before resuming the rappell.

Raumer Handy I haven't personally used it, but I have been told that the shape has been chosen to accomodate a wide range of rope diameters: the smaller the diameter of the rope, the more the friction, is the concept. In Italy for example caving schools and the cave rescue use 10mm, but 9mm is quite normal for caving, while 8mm is still somehow used for deep alpine caves explorations. Also the Handy could be used as additional brake while canyoning, so with another range of ropes. To tell the truth, I never heard a negative comment about it until now, even from US cavers who use it.

Friction on thinner rope Well, if we talk of 8mm, neither a brake biner nor, my guess, an Handy offer enough extra friction. And infact, expecially if long drops are to be negotiated with, the standard suggestions (in Italy, of course) are to use either (or even all together) a S+C threading in the bobbins and/or the rope fed also thru the descender biner. And to be ready to, properly, use extra friction tricks, like the rope wrapped around the leg.
Last but not least, I totally agree that the Freino is a nice concept made with the wrong material: alloy will likely last for a very short span of vertical caving. Given its cost, I can likely buy at least a couple of steel biners and happily use them for a decade each before having to dump them.

[NZcaver]

Last but not least, I totally agree that the Freino is a nice concept made with the wrong material: alloy will likely last for a very short span of vertical caving...

I use one, but I haven't done much mileage on rope since I got it. We'll see how long it lasts. Anyone want to try making some out of stainless...?

[fuzzy-hair-man]

Last but not least, I totally agree that the Freino is a nice concept made with the wrong material: alloy will likely last for a very short span of vertical caving...

I use one, but I haven't done much mileage on rope since I got it. We'll see how long it lasts. Anyone want to try making some out of stainless...?

I was being quiet but....

Three other problems I have withe the Freino apart from it is not a maillon is:

The attachment is not large enough to thread a bight in the rope through to lock off at least not how I am used to. Threading it through the carabiner part in my opinion makes it more likely to inadvertantly unscrew the gate.

The Screw gate is on the bottom side so it is hard to observe if it comes undone.

The path that the rope takes after leaving the descender might cause the rope to rub on the side plates of the Simple or Stop possibly causing rope wear and/or damage. I don't know about this last one I haven't tried a Freino.

Other than that I like the idea.

[Tubo Longo]

I was being quiet but....

Three other problems I have withe the Freino apart from it is not a maillon

That's life: you can't have it all...

The attachment is not large enough to thread a bight in the rope through to lock off at least not how I am used to.

May be the problem arises if you use rope diameter like 11mm I haven't used it, but according to the pics and the tech. info from Petzl you should have enough space to make a full lock off. See
http://en.petzl.com/ProduitsServices/M4 ... 2500-A.pdf

Threading it through the carabiner part in my opinion makes it more likely to inadvertantly unscrew the gate.

I don't see how this should happen: the auto-lock require to pull down AND twist the gate in order to open it. If you un-lock the bobbins, you first pull the rope straight out horizontaly and then immediately up, for braking action and/or to finish to undo the lock. Quite the opposite action.

The Screw gate is on the bottom side so it is hard to observe if it comes undone.

More than the bottom side, I would say the other side respect you. I don't like at all the idea to have the gate out of my view: how could I check it?

The path that the rope takes after leaving the descender might cause the rope to rub on the side plates of the Simple or Stop possibly causing rope wear and/or damage. I don't know about this last one I haven't tried a Freino.

I don't see this much, really.

[paul]

Caver on rope below you Well, the scenario doesn't count in many important factors, like how far away is the upper caver from both the lower caver and the rebelay, what kind of rebelay, etc.
But I don't really think the static weight of the lower caver alone could force the bobbins thru the brake biner, not to speak to deform or even break it: just think how a pick-off ends, with two cavers hanging from one descender. May be the combined dynamic forces resulting from the fall of the lower caver and the rebelay failure could damage (to what extent?) the bobbins, but not surely a static load.
More important, in that scenario, is the fact that the added weight applied to the rope will make impossible to continue the rappell (basically, it will be a huge bottom brake) and so the upper caver will have to changeover and downclimb or, more easily, wait for the lower caver to get to the bottom (or past another rebelay) before resuming the rappell.

It's difficult to explain without diagrams: but think of the bobbin as a lever. In normal use, with no downward pull on the controlling rope, the bobbin is angled upwards from its attachment karabiner because it pivots about the point where the rope from above exits the lower capstan (or pulley or bobbin depending on your nomenclature) with your body weight acting on the attachment end.

Also in normal use, some downward force is exerted on the top of the bobbin by the contolling hand gripping the rope. This force is nowhere near your body weight so the angle of the descender isn't altered much (plus with a braking krab, the direction the rope is pulling the top is redirected).

As you said, you didn't think the weight of a caver on the rope below would be enough to be a problem because of the case of a pick-up when two cavers hang from a single descender.

However the imortant difference is this: when two cavers are attached to a single descender in a pick-up situation, their combined weight is acting on the *same* end of the descender: the attachment end. When a caver below hangs on the rope, their weight will be on the *opposite* end of the descender.

This will cause the top of the descender to be pulled downwards. Yes, this would make further abseiling practically impossible. BUT if their weight exerts a shock load due to an intermediate belay failure, and there is not much rope in between to absorb this shock load, it is possible for the top of the descender to be pulled downwards with some force and if a separate braking krab is used, there is a danger that the top of the descender could foul the krab and twist the descender so that it is not in the usual vertical plane (as was Potholer's point) and then cause deformation and damage as there are two large forces (your weight and the shock load) acting on opposite ends.

This is the reason for the recommendation of the Raumer "Handy" in "Alpine Caving Techniques".