Climbing on a single half/twin rope

Please refrain from the "only use climbing gear as its intended" comments I'm interested in the details here"

I'm looking at picking up a set of the PMI Verglas ropes that are rated as both halfs and twins for use on big alpine routes (raineer/denali/etc) but it seems like most people use only one rope for all there glacier travel. Is there any reason why you couldn't climb easy 5th class pitches using only a single half/twin rope?

The motivation is that dealing with two ropes can be a pain and that this would be a way to move through easier ground with an extra level of assurance beyond soloing. Furthermore it seems like when climbing on halfs, one rope is going to take the majority of the load in a fall. This makes its seem like to some extent you are essentially climbing on only one rope anyway. Is this in incorrect assumption?

While I can see it certainly shortening the life of that rope, is there any reason that a single half/twin rope couldn't stop a fall?

The things I've considered and are concerns so far are:
- Exceeding ultimate tensile strength (seems unlikely)
- Thinner 8.1 mm rope could get sliced (perhaps but they make 9.x mm singles)
- Excessive elongation resulting in hitting more ledges

As benefit:
- An half rope is a softer spring than a single so maybe there are some load limiting behaviors on ice screws or pickets
- Ease of rope management

Does anyone out there climb in this style?

Yup, climb on a single 8.5 Genesis.

In terms of impact force, Jim (name?) at Sterling did some UIAA Single Rope tests (80kg) on half ropes (one strand) and found kN similar to thin singles (~9.4kN) - he doubted they could hold as many such falls though. As for elongation/ledge-smacking, for the most part in lower angle alpine climbing the rope is there to prevent catastrophic falls (read: off the mountain entirely, or onto major benches/ledges)... so an extra 2m of stretch is academic at that point (especially given how many ledges there are to smack on alpine routes).

The weight differences are coming down though - 52g/m (compared to 48g/m for the genesis)

I do it. Usually when soloing is not desired and the leader will not fall but the follower wants a rope or simulclimbing. I also have a 30m glacier rope for short roping my wife or someone else up a short technical section in the alpine or a quick rappel.

Now that I have a 9.2 Nano (52g/m) it seems silly not to just bring that. I would have to *really* need the weight and space savings of something like a 7.8 monster to leave the rated single Nano at home.

I climb on a single 8.9 mammut serenity

Awesome! Thanks for input!

Maybe this is ridiculously stupid but...
I've been looking at the Verglas as well because of its versatility and I was also considering bringing just one 60m and doubling it in half (and knoting one end of course) on moderate stuff if a partner and I needed to pitch it out. Belay just like a regular twin rope. My potentially bad .02

Wannabe wrote:Maybe this is ridiculously stupid but... I've been looking at the Verglas as well because of its versatility and I was also considering bringing just one 60m and doubling it in half (and knoting one end of course) on moderate stuff if a partner and I needed to pitch it out. Belay just like a regular twin rope. My potentially bad .02

If you got a bi-color or bi-pattern rope this might be doable but perhaps my intentions were not too clear.

My desire is to have the ability to make a 60m rappel (thus: need two 60s). I also hate having to deal with belaying two ropes when its not necessary (such as a lot of alpine situations where falling is unlikely but you do want to prevent disaster). Its possible to meet both those needs with

- A single 60m and a tagline - but taglines aren't cheap and its sort of a niche piece. I also hate spending money on niche pieces of equipment. In this setup, its also harder to share loads since the single (9mil) weighs much more than the tag (5-6mil).

- Two single ropes - this is heavy

One of the advantages with half ropes is that you can avoid rope drag by clipping alternating pieces - this is what you will accomplish if you were to double up a single 60m rope as you suggested. This technique though would limit you to climbing only 30m and unless the halves were REALLY distinguished it would be hard to recognize which one to clip. Usually with half ropes they make one blue and one neon yellow or something obvious.

The idea I was trying to pose was bringing two 60m half/twin ropes so that on a difficult pitch you can use them properly (read: together) and also be able to make a 200 foot rap if you need to bail. By climbing the easier pitches and traveling on glaciers with the 1-half/twin you merely save time on rope management and can therefore move quicker.

I think the approach you are considering would work, although it might be somewhat sloppy.

Wannabe wrote:Belay just like a regular twin rope.

I missed this in your post. THIS IS IMPORTANT

Remember that to climb on TWINS, you clip both strands to each piece. When you do this, you put two springs in parallel (a rope is a spring) and thus double their stiffness (k). This means that the rope needs to be specifically design for this application and be made less stiff.

There can also be abrasion between the two ropes in a fall and so twins tend to be designed so that they won't cut through each other.

As far as I know - there is no single rope that is rated also as a twin rope because single ropes are designed to be used alone (hence the name).

I think your technique would probably work in HALF-ROPE-MODE where you alternate clipping ropes into a piece but never clip both ropes into the same piece.

Some ropes (like the PMI Verglas) are rated as halfs and twins so that you can do either - but this is not the norm. Make sure you understand the difference between the Half and Twin technique and never clip two non twins to the same piece.

Based on my quick calculations (and assuming the numbers quoted online are correct), you could save about 19 oz over 60 meters between a thin single like the Sterling Nano and the PMI verglas. That is a pretty huge difference in my book.

Seems reasonable to use it in the manner you're describing, with the obvious caveat that it won't be as durable for number of falls nor sheath abrasion.

Yea i'm not saying it's insignificant. it's just not enough weight to be worth the risks/downsides most of the time for me. My partner's ropes are heavier than the verglass too which closes the real world gap in my case. There are instances where I would take the lightest cord I had which would end up being a single half rope. when there was no nano in the quiver it was more attractive.

Sorry Chris...it probably didn't seem like it, but my post wasn't specifically directed at you. It wasn't my intent to be snarky. :-) I was just trying to figure out the weight difference and thought others might be interested.

I was just thinking that on a long alpine route with very little (and low-rated) 5th-class climbing like most routes on Rainier, the idea of using a single Verglas seems mighty appealing due to the weight savings.

No worries. It's definitely a technique to consider. A single half rope in the flatirons doing the direct on the first in one pitch.

Flatirons

There was a very good thread about using single ropes over on Cascade Climbers:

Linky

Upshot is there is a good variety of pullcord techniques posted, as well as specialized ropes (Esprit) that cater to the ultralight alpinist.

Hope that helps, even if it's only somewhat on point.

Using a single 7.5 Mammut Twilight half-rope on a classic mountaineering route - The Midi Plan Traverse - in the Alps.

Hey John,

I've brought one or two of those PMI ropes on a bunch of alpine routes all over the place. Used them for hundreds of pitches of rock, snow, ice, until they were literally falling apart from end-to-end.

I've used just one strad to lead rock quite a bit. I also like doubling one up and climbing with one rope (two strands) in half rope technique for simulclimbing. With what amounts to half ropes, each simul block is longer because you don't need as many runners and 30m is a good distance between climbers.

The only thing i'd be worries about is rock fall or sharp edges chopping rock. As far as taking a lead fall onto one strand, it's just a little stretchier. I think those are some of the best alpine ropes around.

John, good topic and I think this thread has already answered your question. I just wanted to reiterate that I often times bring along a single half-rope to save weight, under certain circumstances:

The leader most likely will not fall.
The route has numerous opportunities for bailing, and a 30m rappel is sufficient.
The approach is long enough that the weight savings is worth only having one rope.
The second needs/will appreciate the security of a belay.

I think it is ok to assume that a single half-rope will hold one big fall (and most likely repeated big falls, though be weary of this gray area). However it is more likely to be cut on a sharp edge than a single rope, and has a bit more stretch.

One good example of when I have used a single half-rope was when I climbed the north face of Lone Eagle Peak. 8 mile approach with overnight gear, and the climbing was never harder than 5.7

YER GUNNA DIE!

John Maguire wrote: As far as I know - there is no single rope that is rated also as a twin rope because single ropes are designed to be used alone (hence the name).

Actually the Beal Joker is certified as a single, half & twin. It is a super-versatile rope, but at 9.1mm will be heavier than the ones you are talking about. might be a good rope to pair with a skinnier rope rated for half & twin though. the metolius monster comes in at 7.8mm, so paired with a 9.1 would probably weight as much as a standard pair of halfs. although personally i have found super skinny ropes not to be worth the weight savings in use. the skinnier the rope, the more tangles, rope messes, wind issues, stuck when pulling, etc. issues you seem to have. these seem to be more problematic on rock routes than ice.

(I have and regularly use the PMI 8.1 ropes)

Personally, if I'm going to carry two 8.1 strands to a climb, I'm certainly going to lead on both. If you don't want hassle just use them as twins. I don't mean any offense, but trailing one perfectly good rope as a tagline and leading on a marginal rope just seems silly.

Now, on the other hand, I have climbed with one strand when we simply only carried the one 60 meter 8.1 mm rope. The situation was easy, but exposed, climbing and a horrific approach. No rapping required.

In regards to falling on a single strand of half rope, I'll paraphrase Jeff Lea, who was on the UIAA safety commission when these tests were developed and has written about this on forums somewhere (can't remember where):

The thought was that a half rope had to be able to survive one 'nightmare' fall, since this could occur during the intended use. The problem is that many half ropes on the market would break on the second fall, so there would be no comparison between ropes. Any test where passing is a value of 1 is pretty bad from a statistical point of view. So the drop mass was reduced until those ropes that survived one normal drop test survived 5 of the modified drop test. Research at the time showed that all ropes that passed 5 drops on the 55 kg mass also passed 1 drop on the 80 kg mass. Now some ropes might make 6 or 7 and you could compare which was more durable.

Relistically, every fall onto a double rope is the same as a single-rope fall, unless you have them clipped like twins.

People often lead on a single strand of half rope, with the caveat that they retire it if it ever catches a fall. At first glance this makes sense - tested as singles they fare poorly, and you were abusing the gear. But wait! Every fall caught in a double rope system is entirely on a single strand. No one retires halts after a single catch in half-mode.

So, why are they rated differently? The post above has it right:

UIAA falls don't mean much.

Chris Drover wrote:I don't mean any offense, but trailing one perfectly good rope as a tagline and leading on a marginal rope just seems silly.

Silly until you realize how much time is spent on rope management while climbing on two strands. I'm definitely no expert on it, but the times I've been part of a multi-rope team, the extra time spent flaking was frustrating, especially during poor weather and small belay ledges.

I get what you're saying, but I think the efficiency improvements are absolutely worth it. And all other things being equal, less time in the danger zone = lower chance of danger.