Cinch rope compatibility

I climb a lot SRT on a Cinch myself Xman. I realize there is some issue about the Cinch catching a hard fall. I guess one thing about the Grigri is purportedly it slips before it damages the rope. Sounds like the Cinch behaves more like a Gibb's ascender/rope grab and severs the rope under high loading.

Of course IF the loading that severs ropes is high enough, it's in the same ball park with toothed ascenders - they shred the rope around 1000 lbs.
 
Ron

Treemagineers have done some tests looking at the dynamic performance of lanyard adjusters e.g. Trango Cinch and Petzl Grillon. We performed 30cm, 1m and 2m dynamic drops on all adjusters.

As Taylor said, the manufacturer specifies the use of dynamic lines in the Cinch. After dropping a 100kg (~220lbs) steel mass from 2m (~6.5ft) into a short (~1.2m) singled work positioning system (Mammut 10.2mm Supersafe dynamic rope), the Cinch released reliably and functioned as normal. The peak force generated averaged 7.398kN.

The same test performed on a Grillon with low stretch rope resulted in an average 8.181kN force, and it was not possible to operate the device without removing the test mass.

The slippage was marginally greater on the Grillon, but obviously not enough to dissipate significant energy.

Our experience showed that if the same test is performed using low stretch rope in the Cinch, the device is likely to fail, not that the rope will be severed.

Trango have communicated clearly in their user instructions i.e. that dynamic lines should be used. There is an increased risk to the user if low stretch lines are adopted, both in terms of higher arrest forces and device failure.

2 metres is a very large fall (which in trees is unlikely to be obstacle free), and 7.4kN is an arrest force that may not be survivable. Just because our gear may be able to endure these tests unscathed, it doesn't mean that humans can. Better to identify and manage 'potential fall distance' i.e. minimise slack.

Chris
 
Thanks for the information, Chris.

xman(Xian), Sounds like you are placing yourself in a very dangerous situation... and you are clearly aware of the danger. Why continue this way when you can see the potential outcome?
 
Guys, are we mistaking climbing devices for fall protection? For example, do a drop test on a toothed ascender on static line or dynamic for that matter and see what you think, yet no one questions the toothed ascender as a climbing device.

How many hang their lives on a Croll? So how does the Croll perform in a similar drop test?

What would happen if a Gibb's ascender were tested the same way? It would very likely sever the rope.

As for the Cinch on a lanyard, was that tested in a drop test? In a lanyard application the force on the Cinch would be about half the shock load due to the two strands of rope catching the fall.

Regarding the shock to the human body, has anyone tested or calculated the forces on the human body free falling two meters on a DDRT setting? Let's think about that. The rope would be twice as 'static' because there are two strands supporting the load. The load on the friction hitch would only bear half the shock load, hence it may not slip as readily as we think. Moreover, has that even been tested?

I'm not saying we should push the envelop, but we do lots of things that are accepted as safe when they may not be. True, a Cinch may not be a good factor 1.7 fall device, but then would a DDRT setting be any better and who ran the test to determine that?

The author of "Life on a Line" says neither the Grigri nor the I'd is good for rescue work because at rescue loads they blow apart. Yet we still have every confidence in a Grigri for climbing.

So I think it is entirely reasonable to ask if we are expecting climbing devices to serve as fall protection. But if so, what gear will meet fall protection requirements and what will not?
 
That's quite alot of questions Ron!

Toothed ascenders have been a cause for concern for some time, especially in tree ascent where it is sometimes difficult to 100% identify the exact route of the remotely installed line. A considerable amount of testing has been done on the subject. This was partly responsible for some recent evolutions in rope and device design by a number of manufacturers.

As you suggest, Doubled rope systems generate much higher arrest forces than single rope systems, assuming that the material dissipates energy in some way. This has also been tested. For work positioning systems, the key is understanding and managing the risks (minimising slack).

There have been attempts to assess the range of forces acceptable to the human body wearing a correctly fitting sit harness, but it is of course not easy. The expense and variability of outcomes makes this an area of work for anyone that cares to contribute considered thought! At the moment, much of the quoted information is drawn from the crash test dummies used in vehicle testing and the testing prior to space exploration. There seems to be more money in those industries!

Chris
 
I'm not trying to be cantankerous, but the fact is we use a lot of gear that would not fair well in a 2 meter 1.7 fall factor free fall drop. If that is to be the minimum standard for tree climbing gear then we need to include all toothed ascenders, Gibbs and possibly all Gibbs type ascenders as unacceptable climbing devices.

And if I may ask, how does the Unicender fair in this type of test?

What I fear is happening is that we're applying, or may I be so bold as to suggest, misapplying tests to gear use. I.e. the 1.7 FF drop test is a severe drop test primiarly designed to test dynamic rope. Falls are both common and expected in rock climbing which is why they use dynamic rope instead of static rope.

If tree climbers are going to compare tree falls to rock climbing falls shouldn't we be climbing on dynamic rope in the first place?

So again, I think the question must be addressed, are we expecting climbing devices to serve as fall protection? Warning, that's kind of a trick question. If you say yes, then I'm gonna ask what the minimum requirements are and what gear and techniques meet those minimum requirements?

If you answer no, then the whole issue goes away doesn't it?
 
"...Just because our gear may be able to endure these tests unscathed, it doesn't mean that humans can. Better to identify and manage 'potential fall distance' i.e. minimise slack." - Chris

I like that!
 
Ron, I like the way you're trying to pin down the squirming issue of work positioning climbing vs. high angle fall arrest. It sheds significant light on the discussion.

I have the tendency to reject the argument that tree climbers are compelled to climb on ground anchored SRT settings of unsure strength, ie: the rope is over multiple branches and the climber can't be sure that one won't break out and drop them a few feet. It's the climber's choice to put themselves in that situation. No climber "must" climb on an unsure SRT anchor. Through careful inspection with binoculars and smart load testing techniques the climber can reduce the risk to a very small amount. My belief is that many tall tree SRT climbers could do a better job of minimizing the danger from such a branch breakout without requiring their ascent devices to be fall arrest rated.

That's why I think Ron's call to carefully distinguish between work positioning and fall arrest requirements is on target.
-moss
 
Ron

I don't think anyone suggested that a 2m drop was an appropriate measure of 'safe' or what we should plan for. It was however the threshold at which the limit to the dynamic abilities of the Cinch were best illustrated.

Maybe dynamic ropes are well suited to certain tree climbing applications, perhaps when configured with specific devices or when working close to anchor points with little potential for energy dissipation. In other applications, low stretch rope is without doubt better. There may even be scenarios where fully static rope is best suited. All equipment specification should be based on the work environment, competence of the user, abilities of the team, rescue plan, the weather etc etc. Neighbour component compatibilty and correct component configraution are good things to consider when putting systems together.

The EN standards have started to identify the performance criteria that might be appropriate for equipment used in different types of fall protection. The range of applications addressed is far from complete, and the specifications are often out of date. That is almost inevitable in a sector which is evolving rapidly. But as long as we aware of it and don't treat standards like a some sort of 'safety grail', responsible end users can help to show the way forward through good practice.

But all of that is meaningless if the end user either doesn't understand the abilities of the equipment/techniques or chooses to ignore them.

Chris
 
I understand Chris, but the claim has been made that the Cinch should not be used on static rope for tree climbing soley because something happened to the Cinch in severe (FF 1.7) drop tests. It would be extremely unlikely, if not impossible, for a tree climber to experience a FF greater than 1 - unless he unwisely climbed above his TIP.

Be that as it may, I've pointed out other gear that would probably do even worse in the 'standard' FF 1.7 drop test and nobody seems to be concerned at all about them, a Croll for example.

But again, it comes down to, do we expect our climbing gear to serve as severe fall catchers? If so, based on your own data submission:

"...After dropping a 100kg (~220lbs) steel mass from 2m (~6.5ft) into a short (~1.2m) singled work positioning system (Mammut 10.2mm Supersafe dynamic rope), the Cinch released reliably and functioned as normal. The peak force generated averaged 7.398kN..."

That's almost a force of 1700 lbs to the climber! I'd consider that a miserable failure for fall protection and that's on dynamic rope!

So what's the lesson to be learned here? Both a Cinch and a Grillion fail miserably as fall protection for severe falls. I.e. the kind that can only happen if you climb above your TIP AND with the rope tied to an immoveable, non-flexing anchor point.

I think it is inescapable that both a Grigri and Cinch are both totally inadequate to catch falls greater than FF 1.

And, how ironic, that they are both very inadequate to catch falls yet that is exactly what they were designed to do. Of course there is real fall protection gear available which testifies that climbing devices are inadequate to catch falls.

Would it be accurate to conclude that a Cinch or Grigri catching a 1.7 FF would kill a human?
 
Ron

I don't know how else to say it.....so I have to say it again.

'The lesson to be learned here' is that the user should understand the boudaries of the system and environment they are working with and manage the potential fall distance accordingly.

Training/experience/competence are of course a key factor here.

It is possible to have the most fantastic energy absorbing ability built in to a system, but fall so far that the energy created still leads to equipment failure when the fall is arrested. This issue is all about matching task with equipment and behaving correctly. There is no way to completely delegate 'safety' to equipment.

For reference, a 2m fall can happen if you fail to manage slack. It is not only possible when climbing above an anchor point. Fall factors are difficult to apply to tree work sometimes and are often inappropraite and misleading.

Your line of arguement seems to be heading toward justifying Fall Arrest systems for everybody that works at height, just in case a large fall is around the corner. There are many reasons why we don't work in Fall Arrest, one of the most obvious being the absence of a Clear Area to fall into. Branches and the ground will often be impacted before the Fall Protection system can do its' job. Hence our adoption of Work Positioning techniques which requires the climber to be vigilant and manage slack.

For Work Positioning, both the Grillon and the Cinch appear to be fine if configured and used as the manufacturers have instructed. Although only one is certified to an appropraite standard for industrial work positioning.

Chris
 
Thanks for your concern,

However I always back up my primary with a secondary due to the fact that mechanical devices can and will fail with improper use and inspection. Now, by the same token, I have also seen misuse on cordage that has also failed! So is it the fault of the user knowing these limitations or the one who does'nt adhere to them! Never the less I will still continue to climb SRT knowing/and respecting my limitations as oppossed to DRT which has it's downfalls. Everything in moderation!

Stay tied in,

X-man
 
Chris,
I'm not disagreeing with you. It's always better to prevent a fall than to catch a fall. But the issue here has been that if we test a Cinch in an inappropriate way, i.e. a 1.7 FF drop test on static rope, then we get predictable results.

My point is that if a climber puts himself in a position that can develop a 1.7 FF, it's gonna take a lot more than a Cinch or Grigri to save his life.

If a climber stays below his TIP, it will be impossible to develop anywhere near a 1.7 FF. In fact, it would be difficult for a tree climber to experience even a 1.0 FF fall.

My question is are we sure we are justified in condemning climbing with a Cinch on a static rope because of implications from 1.7 FF test results? AND, if we are going to condemn the Cinch thusly, then we should also apply the same logic to all rope grabs, such as the Croll, Ascension, etc. because they would all miserably fail the 1.7 FF drop test.
 
Now you can always back up your cinch or Gri-Gri with a prusik of choice, however, it is a little cumbersome... I use two lines in large trees so my Primary is ALWAYS backed up with another cinch, Gri-Gri, shunt, ascension, croll, etc. I would never recommend this to an unseasoned climber that does not understand cordage or physics! It does work for me and I always inspect and replace mech. devices at a drop of a hat! No signs of wear/ no scare!

Now Petzl is coming out with a new descender/ascender that is far superior than the I'D, Gri-Gri, etc...

Stay tied in,

X-man
 
The New Petzl device is called "RIG" and is not available as far as I know until January, unless you know someone in the secret society! It runs around 155.00 US Dollars so far... I have not tested one yet so I can only tell you what I have heard from confidencial sources that it is way better than anything out at this present time and it should help resolve SRT climbing to a point! Don't quote me on this though please!!!!

Stay tied in and be patient my sons,

X-man
 
I don't get it - it's bigger and heavier than a Grigri, doesn't have a panic lever or position lock feature and costs nearly twice as much as a Grigri?????

Edit:
And it's only spec'd for 10.5 - 11.5 mm rope. Sooo, if you want to stay in manufacturer recommendations, ropes like Lava, Tachyon, PI, etc. are too big for the 'Rig'.
 
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