Seeking (hopefully informed) opinions about the use of twin ropes with a three person team.

It is my understanding that even the thinnest twin ropes (~7.5 mm) are perfectly safe to bring up a following climber on a single strand (two followers, one on each). However, while browsing around on the Mammut site, I came across this statement:

http://www.mammut.ch/en/ropes_handling_practicaltips.html

Three Person Rope Teams

Longer routes are sometimes climbed in three person teams, whereby one leader belays two seconds at the same time. 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. For three person rope teams half ropes can be used, but never twin ropes.


So, wtf with the last sentence (I added the boldface)? Obviously there is the concern of sharp edges, but frankly an 8 mm half rope isn't going to perform much better over a sharp edge than a 7.5 mm twin. Has anyone else seen this piece of advice somewhere else?

My thought process is that they simply haven't tested the setup in the lab, and therefore say not to do it for legal reasons (ie the 'not intended use of product' issue). Any other thoughts?

Edit: I'll add that I pose the question only out my desire to totally understand any and all pieces of equipment related to climbing, and currently do not even own twin or half ropes.

It's not the diameter nor sharp edges, it's the drop testing cert that differentiates the 2 types of rope and what they are used for in managing a climber fall. I wouldn't say they haven't tested their product enough; these things are usually over-tested in their own house, if there is such a term.

However, also it is the belay device in the situation as well. Some devices must have the 8.5 as the minimum to safely belay 2 seconding climbers at the same time.

I have done it, and it worked fine. the two seconds fell a few times and the single twin line held. I' m not sure I would ever do it again though. It feels like climbing on accessory cord, too scary.

Doubles are the ticket. I did Babo in January and we had a team of three with double ropes. The second and third could easily simul-climb with no problems. It went fast. Do not buy twins, get double ropes!

Twins have their place. I wouldn't discount them completely.

PMI Verglas 8.1mm, certified as both. That's what I use.

I think there is some confusion of terms going on. Correct me if I'm wrong, but as I understand it: doubles refer to half and twin ropes. Half ropes are clipped to alternating pieces; twin ropes are clipped together.

This Rock and Ice article explains it:
http://www.rockandice.com/inthemag.php?id=8&type=gearguy

I think Andy has the best idea with getting the PMI ropes certified as both half and twin ropes.

I use Petzl Dragonfly 8.2mm.

But now I am confused...If a rope is certified as half, wouldn't it be automatically certified for twin technique too?

Doubles & Halfs as terminology are usually interchanged.

Twins are not.

Bob - no -- it's because the drop test uses a half-mass (more accurate, certed with less than full-mass); whereas twins must perform with a full-mass.


What makes the half-rope work as the cert designs is perfect world protection placement intervals; as one rope initially arrests the fall the alternate strand picks up the remainder; supposed distribution on each strand at independent intervals.

But pro is never equally spaced & I rarely alternate unless placements are straight forward (1 side of the route gets green rope, the other side of the route gets purple rope); thus reducing rope drag, the obvious concept -- but what if the first 3 placements are green and then the next 4 are purple? -- rope drag is more my concern; but that's outside of what the cert actually means.

One unique advantage of the half is you can limit your fall distance when overhead clipping; which you can't do with a single or twins -- you take the off-strand and bring it over your head instead of the strand that you just clipped.

No, it actually explains pretty well that each half strand needs to manage a portion of the energy from the full-mass and be independent on the protection over the duration of the climber fall to maintain the certification.


I would say that most people, when they say Double -- they intend to mean the Half rope certification.

Granted, the question asked was with regard to seconding climbers. The issue of fall protection by using Halfs opposed to Twins, is that you never really can manage the system by keeping all slack out of it; so Halfs are the default as they can handle a leader fall by single strand and keep energy limited.

e-m-p -- I just explained it.

Granted yes, the mass isn't exactly half. More the point was that it wasn't a full mass in cert testing and why it wasn't a full mass.

The number of falls is helpful, but not the primary to getting the strand(s) to perform within cert. One big fall on any rope and I'm tossing it, but that's just me.

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.

If you had a situation of moving nylon over non-moving nylon, it wouldn't be due to a rope's certification, this is more a rigging problem.

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?