UKC

How skinny is too skinny for a tagline?

I have a 50m, 6mm glacier/scrambling rope (the one from Edelrid that is supposedly static, but rated for one dynamic fall as a twin). I use it almost exclusively for complex ski-touring where weight is a real issue. I'm considering cutting myself 50m of 3mm accessory cord to use as a tag-line in longer abseils but can image this being a nightmare and getting stuck in every little crack it can find. Has anyone tried this with such a thin set of ropes? 

So you'd ab on a single 6mm? Through what device? One sharp edge wouldn't need much to slice it. 

Through a reverso, threaded through both slots - I've tried it off my balcony and it works fine. Sharp edges do worry me, but I don't see the difference between abbing on a single strand and a double - either way if one strand is cut it's curtains.

I think it's just more friction depending on device, ie two 6mm lines on a Italian hitch, versus one in each device slot. Wear gloves, test on short slabs. Curtains indeed. I say distance used for may matter too if you're working hard controlling it. If it jams pulling through, ascending 6mm cord would be great fun. 

the load is reduced on 2 strands -the cross sectional area in contact with the device and any sharp edges. 

Any thoughts about using a beal escaper instead? Still a snag risk, but probably  easier to handle than a 3mm tag line. I find it hard enough pulling down on a 6mm RAD line when there's much friction involved.

The specs on the Escaper say 7.3mm and up. Not sure how comfortable I'd feel about undercutting that!

Edit: Having said that, I looked again at how it works and I'm not sure what would actually define that limit on rope diameter.

considering no part of the rope is actually being used in the Escaper system (you tie the rope at the end of the Escaper --> and only the Escaper is being run through the rappel anchor). So the rope dimension is from that perspective irrelevant...

But the rope stretch might play a role here... so 7.3mm and upwards on dynamic ropes... But more static ropes should be still usable. The limitation might be there simply for the fact that dynamic ropes of lesser diameter have too much stretch in them, so you're unable to release the Escaper... less of an issue with a (semi) static the OP mentions...

That being said, it would be smart to test the Escaper in a controlled environment (with a backup) at full length rappel and release... If possible in similar ground that the planned rappels would happen... So that you are sure the Escaper releases properly (and doesn't snag on stuff) with the rope you have

for what its worth, i think i went with 4mm for my tagline. i was eyeing up the 3mm in the shop but decided that for me, it was probably slightly too thin to be able to pull comfortably. Ive used it maybe 3 times and never had an issue with snags, but it's always been on relatively clean limestone.

as someone else said, the Beal escaper is a much lighter and less faffy option. i must admit that i thought it looked dodgy AF when it first came out, but it seems to have stuck around which is surely a good sign. i was recommended it as an option by a guide in the alps this year as well

I've taken a 35m length of 4.5mm paracord to act as a retrieval pull cord when a 60m rope would've been too short (45m abseil). It worked but tangle prevention and tangle management was a big consideration (and there was zero wind).

Not sure I'd want to take my chances with 50m of 3mm. For me anyway.. I think it'd be a problem that it's too tangly and to weak to do any hard pulling over edges if needed. I can see it snapping and tangling and getting  your rope up  the creek. Unless you have a specific "perfect" scenario where you know it's going to work, personally I'd rather not.

I've used 4mm in the past, which has been ok, but it is very tangly and hard to pull if the rope is a bit stuck. Obviously it's pretty light, which is great. If I'm going to do lots of abs I use something thicker.

R.e. one strand vs two and the risk of cutting. If you ab on one strand all your weight is on that single strand. If you ab on two strands the load on each strand is halved, so each individual strand is less likely to cut. What this works out to in actual real world risk reduction is anyone's guess, but it seems clear that abbing on two strands must at least be a bit less risky. Not that that means abbing on one strand is unacceptably risky, just more risky.

The most effective way of improving the cut resistance* of your rope is reducing the load on the rope. Two stands reduces the load on each rope.

*I am assuming that either avoiding the sharp edges/contact points of installing rope protectors are not possible in the OP's scenario

I think we abbed on 6mm when coming off Nelion (Mount Kenya) but it was only one of multiple abs and I was less than happy!  

It's an interesting conundrum - each strand is less likely to be cut but, equally, there are twice the number of opportunities for a strand to be cut, and failure of one strand means complete failure.

^^ This. 3mm Mammut cord has a breaking strain of 1.8kn (~180kg) when new, so any snagging up is going to result in a broken tagline.  I certainly wouldn't use the method on any route where I couldn't still get down on my main rope alone.  60m is a long way to re-ascend!

I did consider this, but I think it's a red herring. The two stands will be right next to each other, so will be going over the same rock features in the same way a single strand would.

I'm certain that 2 strands is better not a red herring 

A rope rubbing side to side (pendulum) or up and down (bouncing abseil or jumaring up) over a sharp edge should never happen according to textbook but very occasionally  might happen in real life sometime due to bad luck, mistaken choices or very unfortunate/**** circumstance (or all 3)

When 2 strands are used, each one should only have half the load on each compared to if all the weight was on 1 strand. The tension in the rope getting rubbed on an edge is a big factor in the damage the rope will get from that abrasion. It could be that 2 strands get a nasty chunk out of them, but 1 strand in otherwise same circumstances would've been actually cut through.

Anyway.. best avoided 😉

You'd think that the thicker the rope is, the more resistant it is to abrasion and being cut....?

I can't imagine pulling on 50m of 3mm tag line is much fun for your fingers.  Much the same as a wire garotte.  Personally, I'd consider the 6mm rope as the tag line...

https://edelrid.com/gb-en/sport/ropes/tagline-4mm?variant=4312589

https://youtube.com/shorts/zX9_7VLw-yM?si=etRk2ivtpBY0DSpv

Quite expensive but I bet it's better to pull and less tangly than the normal 4mm accessory cord I've used before. 10g/m so still more than double 3mm accessory cord at 4g/m.

Thinking back I think I have used 3mm as a pull cord before. I think I took an approx 30m length on the cuillin ridge traverse for abs, paired with a 30m rope (not quite long enough to ab off the inn pin with the rope alone, but I already had the rope). It worked well and was a great solution for a big walking day out with one abseil, but it would have been a real pain for multiple abs - tangle factor was very high.

It's not as if abbing on one strand is an option.

https://m.petzl.com/INT/en/Sport/Multi-pitch-rappelling-with-a-single-rope?...

https://www.alpinesavvy.com/blog/rappel-pull-cords-101

Unless I am mistaken, the OP is intending to ab on one line with a tag line?

Outside of the UK, where our cultural inclination to use half ropes makes it uncommon, abbing on a single with a tag is quite popular.

As far as i know it was invented in the Verdon, to abseil into routes. One lead rope and a tag line to pull it down.

I think it depends on the nature of the rock, but quite often one strand will end up in a crack / corner over something rough & damaging, and the other strand will sit next to it on more benign rock

are you sure you need 50m of rope for ski touring? 30m would be about 1/2 a kg lighter. If it's 50 then that's ok with me.

50m of 3mm is going to be a absolute cluster*uck 

Aldi are doing 200m of 4mm polypropylene for £7 in the random shite aisle.

Jk