UKC

Clipping the half rope

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 GeorgeWawa 30 Oct 2014

We've had a hard discussion among some climbing friends about clipping the half rope into runners. The guestion was if one can clip two ropes into the first biner above the stance and then separate them later? I wonder what opinion at this matter have Brits trad climbers who mostly use half ropes?

George.
Post edited at 15:57
In reply to GeorgeWawa:

The general rule is to either always clip both ropes into all runners, or never to do so. You should not mix and match.
 GridNorth 30 Oct 2014
In reply to GeorgeWawa:

I wouldn't. I think it can create a scenario where one rope is paying out rapidly and the other one not. This could cause the moving rope to rub over the other and perhaps melt it. I don't know how likely this is but I did read it in a rope manual that suggested that you should never mix methods.
 Albachoss 30 Oct 2014
In reply to George:

From a friend working in the outdoor industry:

For half ropes you shouldn't clip both into the same runner because in a fall the two ropes act together to catch the falling climber, stretching only half as much as if they were alone. You'll be slowed down much faster due to the two ropes being stiffer than each on their own, so the force on the runner will be twice as high. Next to your stance with little rope out you'll be risking high factor falls which are bad news.

 remus Global Crag Moderator 30 Oct 2014
In reply to Albachoss:

In practice that isn't much of an issue. Data is a little lacking, but if you look at triple rated ropes the forces in the twin tests aren't anywhere near double the forces in the single tests.
 Rick Graham 30 Oct 2014
In reply to Albachoss:

Three accurate and informative posts in a row. This may be unprecedented on UKC.

The only ropes that should be clipped together into a quickdraw are called and rated as "twin " ropes.

Ideally they should be identical and used with a karabiner which is also rated for two ropes. These may not actually be manufactured to UIAA or CE standards.

In 46 years of climbing have never seen twin ropes in use in the UK.

There are many reasons to suggest that two half ropes used as instructions individually is safer than a twin rope set up. Modern half ropes are hardly if any heavier than the lightest twins.
 Misha 30 Oct 2014
In reply to GeorgeWawa:

Agree with the above and also why would you actually want to clip two half ropes together? One half rope is strong enough to take a fall, that's what they're rated for!
 Rick Graham 30 Oct 2014
In reply to remus:
> In practice that isn't much of an issue. Data is a little lacking, but if you look at triple rated ropes the forces in the twin tests aren't anywhere near double the forces in the single tests.

Just looked at the Beal site.

Typical additional impact are significantly higher on ropes used as twins instead of halfs.

Triple rated ropes, up to the 3 tests ,have relatively harsh impact loads as halfs and twins.

Using a light half gives the lowest impact force, just what you need improve the chances of gear holding.
Post edited at 19:00
 Misha 30 Oct 2014
In reply to Rick Graham:

Unless the gear is good and the ground is close!
 jimtitt 30 Oct 2014
In reply to Rick Graham:

I looked at about 15 triple-rated ropes and the difference in impact force for twin/half ropes is between 13% and 20%. Considering the variation between used and new ropes and the behaviour of belay devices it´s pretty well irrelevant anyway. The difference between a belayer holding the fall as a half-rope or twins is more than that and the difference between belayers and belay devices considerably more again.
Mammut say it is o.k to swop systems incidentally. The problem arises as some modern belay devices specifically say you must use them through a piece directly off the belay so either you faff about with two draws or simply clip both anyway knowing that that near the belay any drop test ratings you read have no relationship to the actual fall forces you encounter in real life as knot take-up and belayer movement make the difference, not the rating. I´d clip one personally but wouldn´t freak out if someone clipped both.
 Bruce Hooker 30 Oct 2014
In reply to Misha:

> Unless the gear is good and the ground is close!

And you anticipated a long run out before the next runner... There may be times when you choose to clip both ropes through the same crab but the simple rule for someone that feels they need to ask the question is to clip alternate protection. Or do it and don't mention it on ukc
 Rick Graham 30 Oct 2014
In reply to Misha:
fair do s but then it makes sense to use two draws or a screwgate or two
Post edited at 20:51
 Misha 30 Oct 2014
In reply to Rick Graham:
I was just referring to skinny ropes - too much stretch can be a bad thing though it's not often this really makes a difference. I'm with you in that I wouldn't clip half ropes through the same crab.
 Webster 31 Oct 2014
In reply to remus:

> In practice that isn't much of an issue. Data is a little lacking, but if you look at triple rated ropes the forces in the twin tests aren't anywhere near double the forces in the single tests.

thats because they are tripple rated ropes! that is what they are designed for...halfs on the other hand arent.


 remus Global Crag Moderator 31 Oct 2014
In reply to Webster:

I think triple rated ropes aren't so wildly dis-similar as to be unrepresentative of ropes in general. All ropes use essentially the same design after all.

Of course I might be wrong, but as jim pointed out with triple rated ropes the difference between twin and single tests is pretty small compared to other factors (belay plate, belayer), so double ropes would have to behave very differently to triple rated ropes to change the conclusion in a real world situation.
 andrewmc 31 Oct 2014
In reply to Webster:

All halves will work as twin ropes. I think it was Mammut (but might have been Beal) who stated that this was so widely assumed (on the continent) that all halves are designed with this in mind even if they aren't rated as such. This doesn't mean it is always a good idea on trad; there is a difference between a 'safe' maximum force (harder on you but easier on the rope) and a 'not-ripping-out-the-gear' force.

In the same way that a gri-gri is 'safe' for trad but some people don't use them to minimise impact forces on the gear (not on the climber).
 HeMa 31 Oct 2014
In reply to Misha:

> Agree with the above and also why would you actually want to clip two half ropes together?

Rope management for one... 2 seconds is another similar reason.
 Rick Graham 31 Oct 2014
In reply to andrewmcleod:
> All halves will work as twin ropes. I think it was Mammut (but might have been Beal) who stated that this was so widely assumed (on the continent) that all halves are designed with this in mind even if they aren't rated as such. This doesn't mean it is always a good idea on trad; there is a difference between a 'safe' maximum force (harder on you but easier on the rope) and a 'not-ripping-out-the-gear' force.

> In the same way that a gri-gri is 'safe' for trad but some people don't use them to minimise impact forces on the gear (not on the climber).

Oh dear.

Shall we have a competition for the most mistakes or qualifications needed to make this post accurate?

I have not got the patience.
Post edited at 14:04
 andrewmc 31 Oct 2014
In reply to Rick Graham:
Sounds like an excellent idea. Where would you like to start? A specific example would be more useful than empty criticism?

See also:
http://www.highinfatuation.com/blog/straight-from-the-mammoths-mouth-half-ropes-are-not-twins/

and stole this unreferenced quota from Mountainproject:

'Here is an official response from Mammut:

"The CE- Standard for Half- and Twin Ropes is different regarding the testing: twin ropes are always tested both pairs clipped into one biner (80kg mass, 12 falls), half ropes are... tested as a single rope with a 55kg mass (5 falls required). So the standard for half ropes is tougher than the one for twin ropes as half ropes also offer a great safety margin as a single rope (only to be used to belay two second climbers from an anchor). Therefore, half ropes can always be used in twin rope technique as well (whereas the other way round, twin ropes can not be used in half rope technique). The impact force is not affected by clipping one or two half ropes through the same biner."
'
Post edited at 14:22
 Webster 31 Oct 2014
In reply to andrewmcleod:

for starters i think you missed my point! the difference in stats between a triple rated rope in half or single mode is small (as quoted above) because it is a TRIPLE RATED ROPE! therefore it has met the benchmark criteria to be passed safe and suitable in each of the three situations. im no expert on the technicalities of rope design but there clearly is a difference between a triple rated rope and a half in the way it is made and therefore what it can be used for. they may look superficially the same but that means bugger all! There is probably a substantially larger difference in forces etc if you were to test a true half rope in single or twin mode (though i dobt it is possible to find this kind of stat as i dont see why a rope maker would publish data for a rope used in a style which it isnt suitable for?)
these days there are such things as double rated ropes - ropes which can be uesd as halves OR twins, but you should never mix and match styles mid pitch. I think on the continent lots of peoples "halves" are actually double rated which may be where your previous statement stems from. I havent seen many double rated ropes on sale here in the UK though.
In reply to GeorgeWawa:

My half ropes are also rated as twins, but I pretty much use them in half rope style all of the time unless i've got a plum straight line.

I think Twight advocates clipping both ropes into the first runner, in Extreme Alpinism, if its poor or a long run out is expected, something to do with fraying both ropes rather than snapping one of the halfs? Don't have a copy to hand so can't remember for certain.

I've never done it personally but then again i've never taken a huge fall onto a shit runner with an 8mm rope...
 andrewmc 31 Oct 2014
In reply to Webster:
Paragraph 1: I never mentioned triple rated ropes so no idea what any of this has to do with my post?
Paragraph 2a: Firstly I never said you should mix and match mid pitch, so once again nothing to do with my post?
Paragraph 2b: I stated that halves will work in practice as twins regardless of whether they are rated as such or not; you could disagree with this but this is not what you seem to be arguing (I know that not all halves are also twin-rated). Mammut used to not only single-rate ropes even when they knew they would pass the twin test because they wanted people to pick the right ropes for the right task (they have subsequently changed their policy, hence my Genesis are half and twin rated).

So... what was wrong with my post?

PS people have tested the use of half ropes as twin ropes. The forces are larger but not outrageously so (less than double). This should wear out the ropes slower (as the ropes share the force). You will not break a rope doing this. You will not generate a dangerously high impact force doing this (on bomber runners). You may rip gear that you wouldn't have ripped on a single half. This is presumably all similar to using singles as halves although singles are a bit different.
Post edited at 14:58
 Webster 31 Oct 2014
In reply to andrewmcleod:

sorry i was partly responding to the persons post above yours as well who had also commented on my original comment, plus the mix and match was a comment to the general thread topic.
In reply to HeMa:


> Rope management for one... 2 seconds is another similar reason.

Well, in 30 years of trad climbing on double ropes I've never seen the need to clip both into the same runner!
 HeMa 31 Oct 2014
In reply to Bulls Crack:

> Well, in 30 years of trad climbing on double ropes I've never seen the need to clip both into the same runner!

Define trad... as in all leader placed protection or lead placed bolts...

To be honest, I've climbed some lovely routes with roughly 20 to 30m horizontal traverses with only 1 or 2 pieces of protection in between. With 2 seconds, clippin' both ropes on all protection on that traverse is rather nice. Especially, when the traverse is the crux.
In reply to HeMa:

Well, the usual - leader placed pro

And have managed to avoid long traverses
OP GeorgeWawa 01 Nov 2014
In reply to Bulls Crack:

Well, in my 40 years of mountain experience I've done it many times
What bothers me is that they test half ropes with 50kg weight while I weight a bit more - close to 77 actually.
 jimtitt 02 Nov 2014
In reply to GeorgeWawa:

> What bothers me is that they test half ropes with 50kg weight while I weight a bit more - close to 77 actually.

The test weight is chosen for statistical reasons and isn´t related to actual climber weight, the rope still hold you.
There´s no simple right or wrong about clipping one rope or two in the first piece. If you clip both you will increase the force on the piece and therefore the chances of it failing and being exposed to a factor 2 fall, if you only clip one you reduce the chance of gear failure but also reduce the belayers braking ability so increase the chance that they will fail to hold you. As usual it´s better just not to fall off.
 Rick Graham 02 Nov 2014
In reply to jimtitt:

> The test weight is chosen for statistical reasons and isn´t related to actual climber weight, the rope still hold you.

> There´s no simple right or wrong about clipping one rope or two in the first piece. If you clip both you will increase the force on the piece and therefore the chances of it failing and being exposed to a factor 2 fall, if you only clip one you reduce the chance of gear failure but also reduce the belayers braking ability so increase the chance that they will fail to hold you. As usual it´s better just not to fall off.

Neat and accurate answer as usual.

"As usual it´s better just not to fall off. " So true.
Sitting here with a broken ankle, have plenty of time to assess my mistakes and also think about the OP and subsequent discussion.

The situation where the clipping regime is applied can vary from well bolted multi pitch climbing with little chance of hitting the rock to marginal belays and runners on Alpine routes or the Cilan coast in N Wales. Get the impression that not everybody is thinking about all scenarios.

A few questions for Jim ( or anybody )

The friction on the top krab is apparently quite crucial in impact load calculations and presumably actual loads in the real world with all the influencing factors.
Does containing two ropes in a small lightweight krab significantly affect the friction?
In the UIAA twin tests the ropes run over a 12mm bar and presumably are free (just) to each other and so are not constrained in the slight V shape of a modern krab.

This V shape is designed to guide a rope next to the back of the krab to maximise gate open strength.
Are any karabiners actually designed and tested for use with two ropes?

OP GeorgeWawa 02 Nov 2014
In reply to jimtitt:

Thanks. I agree with you. There's nothing simple in this matter. It depends on a certain circumstances.
 krikoman 02 Nov 2014
In reply to GeorgeWawa:

If you want to clip two ropes into the first bit of pro why not just use two quickdraws, with a rope in each?

This solves both problems and only costs one extra bit of gear.
 jimtitt 02 Nov 2014
In reply to Rick Graham:


> The friction on the top krab is apparently quite crucial in impact load calculations and presumably actual loads in the real world with all the influencing factors.

> Does containing two ropes in a small lightweight krab significantly affect the friction?

> In the UIAA twin tests the ropes run over a 12mm bar and presumably are free (just) to each other and so are not constrained in the slight V shape of a modern krab.

> This V shape is designed to guide a rope next to the back of the krab to maximise gate open strength.

> Are any karabiners actually designed and tested for use with two ropes?

Hard to know what you´d actually want to test really or even how you´d test it, karabiners are just connectors between pieces of climbing equipment at the most basic and that´s all the test calls for. The top karabiner friction is virtually irrelevant anyway related to impact forces compared with the other factors, the rope rubbing on the rock somewhere would have more affect than changing the krab and a belayer that isn´t holding the rope considerably more.
 Rick Graham 02 Nov 2014
In reply to jimtitt:
It is obviously complicated with many factors to consider.

What are your comments on the following assumptions?

The top krab friction and rock drag is very noticeable when lowering off a leader in a sport climbing single pitch situation. This may also have significance in a leader fall to the load on the top krab.
All other factors being equal :
a "slippy " top krab will allow more rope stretch but this will be compensated by a pulley effect, the first effect reducing impact force on the top krab , the second increasing it.
a "grabby" top krab will mainly allow the rope between it and the leader to absorb the fall.

I know you discredited the falljunken calculator in another post, but it does acknowledge itself it is a simplistic
version of reality. It does however manage to give approximately realistic predictions of the UIAA test results for ropes knowing only their static elongation, better than nothing if you don't have access to a test rig. It also supports the top krab friction logic assumptions above.



Regarding karabiners, Are krabs ever tested for their suitability for twin rope clipping?
Post edited at 18:02
 jimtitt 02 Nov 2014
In reply to Rick Graham:

Unless one is in the habit of belaying with something tied to the ground the increased pulley effect isn´t going to be of interest, the reduced friction on the top krab just means the belayer goes up faster or there is more slip through the device. There really isn´t that much difference in friction of various karabiners anyway including the DMM Revolver, climber weights and condition of ropes varies more.

No idea if manufacturers ever test twin ropes in their karabiners or how they would if they do, there´s certainly no requirement for them to test ropes in them anyway. There are no standard rope(s) so any testing would be of a dedicated pairing and of little real value as there are hundreds of karabiners available and dozens of ropes.
 Rick Graham 02 Nov 2014
In reply to jimtitt:

> Unless one is in the habit of belaying with something tied to the ground the increased pulley effect isn´t going to be of interest, the reduced friction on the top krab just means the belayer goes up faster or there is more slip through the device. There really isn´t that much difference in friction of various karabiners anyway including the DMM Revolver, climber weights and condition of ropes varies more.

Thanks for that. So not a dominant factor.

> No idea if manufacturers ever test twin ropes in their karabiners or how they would if they do, there´s certainly no requirement for them to test ropes in them anyway. There are no standard rope(s) so any testing would be of a dedicated pairing and of little real value as there are hundreds of karabiners available and dozens of ropes.

This one has always worried me. Having heard of and personally seen karabiner failures on the crag , is this situation joined up thinking?
Surely testing a krab type with one then two ropes would give some indication if further investigation is justified?
 jimtitt 03 Nov 2014
In reply to Rick Graham:

You´ll need to ask a karabiner manufacturer about that, it´s not something I worry about personally but then I tend to go for a more robust type of karabiner myself. Under the sort of load which could cause failure twins are so alarmingly thin that they fit into any karabiner I´ve ever seen.
Twin ropes causing karabiner failure isn´t something which seems to make the headlines much
 Rick Graham 03 Nov 2014
In reply to jimtitt:

> You´ll need to ask a karabiner manufacturer about that,

I have, frequently, when in the outdoor trade in the 80's and 90's, always got a glazed stare and inadequate reply.



> Twin ropes causing karabiner failure isn´t something which seems to make the headlines much

Fortunately not. All the krab failures I have heard about involve single or half rope clipping, but this may not mean that clipping two ropes is safer
The only time I, and anybody I climb with, put two ropes into the same krab is the belay plate HMS.

 jimtitt 03 Nov 2014
In reply to Rick Graham:

Well I´m not really suprised, there isn´t any real point in testing ropes in karabiners as the rest of the stuff breaks first. Either the rope or the sling which is why the test isn´t done with ropes in the first place. I don´t test lower-offs with rope for the same reason. Twin ropes have been around for maybe half a century or more and we don´t hear of problems and it´s hard to see how there could be.
I use 7.8mm twin/half ropes a reasonable amount, they are ideal baggage-wise if your going on a long trip and want to climb big adventure routes and the odd sport routes as well.

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