3 climbers, twin ropes

So.....If I had a couple of ropes 8.5mm that were twins, or a couple of ropes that were 8.5mm that were halfs...

How would the anchor rig, belay device, the carabiner, the rock protrusions, the lead climber's peanut butter and jelly sandwich in the backpack -- be significant to warrant just about all rope makers to say don't use twins to belay two simultaneous seconding climbers?

In other words, keeping all other things outside of a given rope manufacturer's pervue out of the equation; why are twins not warranted for this use?

Twins would suck to belay 2 with because they both are cliped into each pice, making the climbing for the seconds kinda shitty. when the seconds are climbing at the same time, it is a lot easier if the seconds have some freedome in their movements. I would not climb a wandering route with 2 seconds though if there is any danger of them falling. Actually I wouldnt climb with a team of 3 unless you paid me.
AS far as why they say not to do it, I can how the rope that was just fallen on could burn the other one if both were clipped to the same piece, which you MUST do with twins and should NOT do with doubles(halves)

Buff Johnson wrote:In other words, keeping all other things outside of a given rope manufacturer's pervue out of the equation; why are twins not warranted for this use?

If I am reading you correctly, the following scenario should answer your question. If I'm not reading you correctly, please ignore.

I lead the pitch, using twins, clipping both through each biner.

The second starts up, belayed on a single twin.

As they are climbing up, their rope is rubbing against the rope tied to the third climber at pretty much every point above them.

Probably not a big deal if you're trying to move fast and you do it for a few pitches and you can keep the belay tight enough that nobody falls more than a little slump onto the rope. But definitely not a good idea for general practice.

Theoretically, you could clip them into separate biners and be very careful about rope twisting and whatnot and things would be okay. In reality, I'm guessing it would work out to be not worth the trouble.

Related to this: if you're using ropes that are certified as both a half and a twin, you shouldn't bring up a second and third on separate strands if you're using them as twins.

I was watching 'The Alps' IMAX film the other day and noticed during the huge-limestone-cliff scene -- that they were belaying two seconds off twins. Not sure why it stood out to me, but anywho...

Guessing this might be common/popular in Europe.

Although a lot of good points have been made regarding possible hazardous scenarios. Chris is the only one that is addressing the statement made my Mammut concerning dangerously high impact forces. There statement regards leading not seconding. Even a "second's" rope completely impinged by the other "second's" rope would not generate a high impact force (unless that second went above the impingement point and the fell - theoretical factor 2- pretty much close to impossible). You can see in their statement:

"If two single ropes are used, the leader must never clip both ropes into the same protection point, otherwise a dangerously high impact force can develop."

where the concern lies. Chris hit the nail on the head:

Chris Drover wrote: The problem is that passing more than one dynamic rope through a single piece of pro increases the impact force on that piece

But, passing more than one dynamic rope through a single piece of pro is exactly what you must do with twins and exactly what you must not do with halves.

What is confusing about Mammut's statement is the next sentence:

"For three person rope teams half ropes can be used, but never twin ropes."

I tend to believe there is an error in this statement because clipping both ropes into each piece is essential with twins and does not generate high impact forces as result. Clipping both ropes into each piece with halves should not be done because it may generate dangerously high impact forces. This is only true if you are being belayed on both strands which of course you would be. Conversely, I climb with parties of three often. But, I don't own halves or twins. We just use two single ropes. The leader leads on one rope and trails the other clipping the trail line into gear only when directionals are necessary. This does not pose the "high impact scenario" mentioned by mammut because only one rope is being belayed, thus only one rope catches the fall.

Parties of three are a lot of fun and almost as fast if everyone knows what to do. Anyone care to join me/us? Sorry for the long winded post.

don't really see why that (impact on lead pro) is an issue with seconding, unless there is a change of direction; & even so, both seconding climbers would have to impact the protection at the same time.

Though it is a point that when leading on halfs, you can reduce the impact on protection gear by clipping only one strand.

Why does this change with the multiple certed strands? It really doesn't; you just don't want to mix between twin & half method on the same pitch when leading. This does change with a three person team; you don't want the same strands going through the same biners, even if they are multiple cert rated.

Greg D wrote: What is confusing about Mammut's statement is the next sentence: "For three person rope teams half ropes can be used, but never twin ropes." I tend to believe there is an error in this statement...

Putting the friction issue aside, I'm not following your comment. Half/double ropes are designed and certified to standards by which a single cord is supposed to handle a fall or edge at a particular level. If I understand correctly, certified twin ropes (excluding those also certified as doubles/halfs) are never tested in a single-cord scenario. Someone tell me if I have that wrong.

That being the case, why would it be the least bit surprising that a manufacturer would only recommend putting a person on a single line if it's a half/double rope? They definitely don't maintain separate standards for leading versus following. Falling rocks don't care, either.

I do understand the reality that there may not be much difference in durability, but the mfg is concerned more with their certifications and liability.

That's all basically correct, Avery. It comes down to the certs; as the half-strand is more applicable to manage lead fall energy to the climber and protection (even though the full mass isn't tested -- & I did explain why the full mass isn't tested); the half is then more suitable to use with 2 simultaneous seconding climbers; whereas the twin cert just isn't applicable to this situation.

Andy Laakmann wrote:PMI Verglas 8.1mm, certified as both. That's what I use.

I also use the Verglas and think they are great ropes. I bought a twin (BW) ice floss setup and was able to return them and get the Verglas. I see no reason to chance it (whatever it might be).

If you want to be extreme try having everyone climb on 1 x 70m rope:
-one person leads
-two follow at the end of the rope both tied in ten' from each other.

Then (here's the extreme part) do your full length raps with the fifi hook/bunji cord system!!!!!!!! canyoneering.net/forums/sho…
this youtube link rocks...http://www.youtube.com/watch?v=b8Ute5c2BVk

I'm just kidding don't even think about doing this!!!! Ever.

Chuck Parks wrote:I think the primary concern with two followers on twin ropes is the fact that both ropes are passing through the same carabiner on each piece of protection. If one second falls while the other is hanging, then you could have a scenario where one rope is being dragged with some force across the other stationary rope. This is generally regarded as a Bad Thing. (It's the same reason you don't want to clip half ropes into the same carabiner, unless you're using them as twins.

Ding! Ding! Ding! It took quite a few responses and speculation to get the correct answer, but Chuck finally provided it. You don't want two ropes going through the same carabiner rubbing against one another. It's the same reason that you have to decide when you start leading a pitch whether you are going to use your ropes with Twin or Half technique. If you are going to use them as twins, you must clip them both to every single piece. If you are going to use them as Halves you may never clip them both to the same carabiner. Never switch part way through a climb.

It's not obvious why you would ever want to use twin technique--or twin ropes for that matter-while rock climbing. Half ropes, unlike tiwns, on the other-hand provide you with less rope drag, allow you to climb longer pitches and reduce peak force on your gear when you fall.

Anthony Baraff wrote:It's not obvious why you would ever want to use twin technique--or twin ropes for that matter-while rock climbing. Half ropes, unlike tiwns, on the other-hand provide you with less rope drag, allow you to climb longer pitches and reduce peak force on your gear when you fall.

If I recall correctly, Jim Ewing (of Sterling Ropes) tested some half ropes with the same 80 kg weight that is used to test single and twin ropes and found that the peak forces were actually higher than the reported test values for many single ropes. As Buff pointed out upthread, half ropes are tested on the assumption that one strand will not be absorbing all the energy of the fall. In real life, that assumption may not be true, and peak force on your gear is likely to be higher than if you were using a single rope with soft catch.

As for the use of twin ropes, their popularity seems to be largely with ice climbers and alpinists.

e-m-p wrote: If I recall correctly, Jim Ewing (of Sterling Ropes) tested some half ropes with the same 80 kg weight that is used to test single and twin ropes and found that the peak forces were actually higher than the reported test values for many single ropes. As Buff pointed out upthread, half ropes are tested on the assumption that one strand will not be absorbing all the energy of the fall. In real life, that assumption may not be true, and peak force on your gear is likely to be higher than if you were using a single rope with soft catch.

One thing that works back in your favor is the dynamic belay.

The typical belay device will not hold as much in friction with a half rope as it will a single rope as the strand diameters are typically smaller for the halfs. So, essentially if you don't have those alternating protection intervals, the peak forces from the full mass on a half strand can still be dissipated away from the protection; you just have to be able to control the slippage.

You can switch to a reversino and gain some friction back; but this will hit the pro more.

e-m-p wrote: If I recall correctly, Jim Ewing (of Sterling Ropes) tested some half ropes with the same 80 kg weight that is used to test single and twin ropes and found that the peak forces were actually higher than the reported test values for many single ropes.

I just went through all of the rope stats on Mammut's site and it looks like their Twilight 7.5 mm rope elongates 6% with 80kg which is the least stretchy in the double/twin category (others stretch 9% and 9.5%). The Twilight is listed as a twin only, so I assume the elongation is listed based on two strands. None of their single ropes have elongation of more than 7.2% suggesting a softer catch by all of Mammut's half ropes. If Mammut's offerings are representative of the market, this tends to dispute your point.

e-m-p wrote:As Buff pointed out upthread, half ropes are tested on the assumption that one strand will not be absorbing all the energy of the fall. In real life, that assumption may not be true, and peak force on your gear is likely to be higher than if you were using a single rope with soft catch.

I'm fairly certain that half ropes are tested with the assumption that only one strand will be catching all of the weight of the fall. The greater percentage elongation is why there is less force on your gear. The longer rope stretch causes the force to be exerted on the top piece over a longer period of time. If the other rope is catching you, even better because your force is now being shared in some way across two pieces of gear.

Twin ropes are likely much worse based on the Mammut data because the percentage elongation is smaller than most single ropes and that force is being applied to a single top piece of gear.

Also, no reason why you couldn't soft catch with half ropes, so I'm not sure why this is an issue.

e-m-p wrote:As for the use of twin ropes, their popularity seems to be largely with ice climbers and alpinists.

Which is why I said, I'm not sure why anyone would use them for Rock Climbing. Twin ropes seem like a nice piece of insurance when you're wielding, ice tools and crampons.

reviewed some items, the friction isn't the issue with the seconding climbers. It is on lead if you were to crossover two methods of twin/half on the same pitch; this is where the friction is a concern.

The uiaa cert and in-house strand testing are what drives the guideline for having half ropes allowable for 2 simul seconding climbers.

Don't know if this will clarify or further muck up the rope discussion... When you're LEADING on doubles, you clip one rope through your pro... two is too much rope, too little stretch, too much force on a piece if you whip. LEADING on twins, clip them both through each piece of pro. Nuff said.

But your question relates to 3-person teams, and so is more focused on bringing up 2 followers simultaneously. In that respect, Mammut states that you can belay two follwers up, one on each DOUBLE, but not one on each twin. I climb with both their doubles and twins, and can accept that comment. While the diameter difference is not huge, the twins sure look a lot skinnier. I wouldn't want to hang off a single strand. They're nice for 2 guys climbing long routes when you want to make full-length raps. So no threesomes on twins.

Finally, some belay devices work better than others in the 3-person scenario. I love the BD ATC Guide for this. The auto-lock feature is slick, and if one of your followers falls, it doesn't lock off the strand to the other guy. This beats the heck out of using a regular ATC. I'm sure some other devices offer the same functionality.

We follow ya Bill.

If you had an 8.1 twin or an 8.1 half, which would be okay to use for 2 seconding climbers? The half is.

Most cases, the half is going to be acceptable for the 2 seconding climbers; unless the rope maker says their half can't be used like this. Most cases again, a twin will be unacceptable; it's not designed & tested for this application.

Now, you've now got ropes making multiple certs (they can be either twin or half), which is more a leader concern. It allows for different climbing applications from one pitch to the next, already having the mindset not to cross over clipping strands in the middle of a pitch is a great mindset to keep.

FYI - the increase in force on lead gear by going with twin method instead of half method, if you had the choice, is about 20-25%. It's not an extremely exponential increase, but if you're playing odds with marginal protection, it may work to your favor to go half; course not falling on something you already know is marginal would be a really good idea.

Bill Flaherty wrote:Don't know if this will clarify or further muck up the rope discussion... When you're LEADING on doubles, you clip one rope through your pro... two is too much rope, too little stretch, too much force on a piece if you whip. LEADING on twins, clip them both through each piece of pro.

This is exactly what has been said by others including myself. Although the discussion here has gone a bit astray (belay devices, ropes being burned, etc). If you look at the op and more importantly, Mammut's statement, they are actually making two different statements.

One:

"If two single ropes are used, the leader must never clip both ropes into the same protection point, otherwise a dangerously high impact force can develop."

This is true for the reasons Bill and others have mentioned.

Two:

"For three person rope teams half ropes can be used, but never twin ropes."

This is a different statement. A single twin is not adequate. It is not tested/certified for independent use. Therefore, it should not be used for such. Double/half ropes are tested/certified for independent use.

In conclusion, double/half ropes are ok to use for a party of three as long as the leader never clips both ropes into a single piece of protection. Twins are not.

FYI, a 7.5mm rope has 22% less material (cross section) than an 8.5mm. 1mm difference in ropes diameters is more significant than one might think!

Greg D wrote: ... In conclusion, double/half ropes are ok to use for a party of three as long as the leader never clips both ropes into a single piece of protection.

If you can tell me how this would endanger the seconding climbers, I'm with ya.

Yes, it is correct that the friction issue just isn't there; but it is also correct that there really isn't that much increase in force if you clipped both half strands; it's just not ideal, but it's not catastrophic either; unless the pro was marginal to begin with -- then you have a no fall situation anyway.

Maybe traversing, but straight up, it doesn't really matter to the seconding climbers how the pitch was led as long as they are following on half ropes.

We've had this discussion concerning rope use in many AMGA instructor/examiner meetings over the years and the consensus has been not to recommend the use of even 1/2 ropes (or less) for situations with two climbers following due to the increased risk of ropes cutting more easily at these smaller diameters.

So the current (last I heard) AMGA recommendation for guides was for only single rated ropes to be used for each person following, primarily to reduce the risk of cutting a rope- as a result we tend to use smaller diameter singles to find the right balance. I prefer the Sterling Marathon (9.2?)as an overall single lead line (or dragging up two) in almost all situations due to its great durability for the weight.

Purely pitched snow climbing where there are not edges might be the main exception to this recommendation of not using less than single rated ropes for a follower.

Having seen many single rated ropes quickly melted in half (cut through) from falling rocks and shredded badly in pendulum type falls, I'd personally be nervous to follow on a 8.8mm or less rope due to this potential but consider me 'conservative' in this regard.

I'm not sure that the rope over rope in a single biner is the issue as much - certainly not for following- and for leading, why would it be any different with a 1/2 or twin? If one rope did run over the other, only one would potentially melt, and if the leader is tied into two maybe not an issue?

Knowing the source, I'll heed that cautionary tale - from now on its two skinny singles. Thanks Eli!