Accessory cord for tagline?

Hey guys quick question... has anyone used thin, say 2mm-4mm accessory cord as a tagline, for extended rappels? I've been seeing posts from hownot2 and Mark Smiley using super thin dyneema tag lines, and thought that the weight savings is a valid enough reason to stray from something like the petzl RAD line. So with that being said, when you go accessory cord you save money over dyneema, and as far as I'm aware I can't think of any reason why accessory cord would underperform when compared to Dyneema (besides weight savings). So please let me know if I'm delusional or skipping a step in the process that would make me stray away from the accessory cord for this use case...

It really sucks trying to pull a very tiny cord and it has a tendency to twist. But people do it

Go buy some cheap stuff at home despot, setup a rap at a TR  you can access via walkoff. After your blocked rap is set, walk back down, and tie up any loose lead rope on the ground. Now that you’ve put the entire 60m rope off the ground, pull it with this tiny cord. Now imagine doing this in a hanging belay, repeatedly. Food for thought 

When we tie my two 8.5mm ropes together for a 60m rap it is hard enough to pull the ropes down (depending on friction/anchor circumstances). I’d sure hate to try it with thin cord like you are pondering. But, as mentioned above, give it a test try and see what you think. Just be sure someone above can toss your rope down to you after you give up. 

In the right circumstance it may still make sense.  Super long approach to a route with only one double rope rap and it would make sense to me.

I could see it making a lot of sense on the grand with one double rope rap but normally a cue of people and a high likelihood of getting on someone else’s rope

I have about 150' of accessory cord left over from my attempt to do just this.  Pulling the cord sucks, but you can use a tibloc or MT to help.  You can't (or shouldn't) try to toss the cord, so the first climber down has to flake it out.  I've tried using a small stuff sac rope bag for tossing, but if any wind picks up you are screwed.  

I would just pony up and get a Pur line.

anything smaller than 6mm will turn into a tangled rats nest. 

It bears mention that (IIUC) Mark Smiley uses these super thin cords on snow.

(which may also be where OP is planning to apply such a tool)

I've used 5mm Sterling.  Carried 70m of it in a pack during the climb.

They reccomend using a special knot for joining it to the climbing rope (can't remember name but it's a variation on an overhand (not EDK)).  I also blocked it wth a carabiner since the knot wasn't really big and didn't inspire confidence on some rings.

Instead of throwing it, I had it stacked loosely in a stuff sack type bag (designed for this purpose, borrowed from a friend) so it would spool out behind me as I rappelled, ran it through a quickdraw with the rope on the descent, that kept things tidy.  Only the last rappeller spooled out the line.

It pulled just fine for retrieving the rope.  Stacked it back into the stuff sack at the base of each rappel (you can do this while the first rappeller descends).

Despite all of these details, the system worked really well.  Light, cheap.

Professor Watermelon wrote:

I've used 5mm Sterling.  Carried 70m of it in a pack during the climb.

They reccomend using a special knot for joining it to the climbing rope (can't remember name but it's a variation on an overhand (not EDK)).  I also blocked it wth a carabiner since the knot wasn't really big and didn't inspire confidence on some rings.

Instead of throwing it, I had it stacked loosely in a stuff sack type bag (designed for this purpose, borrowed from a friend) so it would spool out behind me as I rappelled, ran it through a quickdraw with the rope on the descent, that kept things tidy.  Only the last rappeller spooled out the line.

It pulled just fine for retrieving the rope.  Stacked it back into the stuff sack at the base of each rappel (you can do this while the first rappeller descends).

Despite all of these details, the system worked really well.  Light, cheap.

So you did a variation of a EDK and then stuck the biner through that? I was under the impression that you would do a stopper knot + biner block (say alpine butterfly with a biner) and then a double EDK (or whatever knot to join two ropes? with the second being opposite and apposed…

side question.. at what point does it become dangerous to join two differently sized ropes together, with EDK/flat overhand. I know hownot2 has some stuff in this, but it never really got in depth for me enough.z like let’s say I’m running a rope anywhere from 8.9-9.5, what’s the smallest diameter that I should go with in tagline if I decide to use the EDK method?

Noah Gilbert wrote:

So you did a variation of a EDK and then stuck the biner through that? I was under the impression that you would do a stopper knot + biner block (say alpine butterfly with a biner) and then a double EDK (or whatever knot to join two ropes? with the second being opposite and apposed…

side question.. at what point does it become dangerous to join two differently sized ropes together, with EDK/flat overhand. I know hownot2 has some stuff in this, but it never really got in depth for me enough.z like let’s say I’m running a rope anywhere from 8.9-9.5, what’s the smallest diameter that I should go with in tagline if I decide to use the EDK method?

Realistically you can use a flat overhand (EDK) - if you're rapping on one strand, the only "ring loading" force the joining knot sees is pulling it. I have had to set up a 3:1 to pull down my rope with a petzl pur'line (6mm suuuper slippery dyneema) and BD 9.4mm dry. I was using the petzl recommended stacked opposed EDKs - with the skinny cord on the bottom per manual, but the one seeing the force didn't budge. I've really liked rapping on one strand with a grigri, and having the pull cord stacked in a bag on my harness. Keeps it from getting blown around and tangling, plus you only ever have as much out as you need.

A better joining option, in my opinion, is a Gibbs, since it adds stability (resistance to rolling) vs an EDK, but is easier than the two opposed EDKs (when I'm tired, I don't want to be thinking about tying a knot "backwards").

This is a good resource: https://www.andy-kirkpatrick.com/blog/view/rappel-knots-1

Years ago I’ve successfully used 3mm cord on many occasions.(it needs to be as low stretch as possible) As stated many times above, it’s hard to pull becoming a real pain if there is much friction. I mostly used it for ice climbs and it was ok. I got around the tangles by coiling it on a small spool so it unrolled with me as I rappelled. Biner block the rope back to itself and tie the thin cord to the biner. The biggest issue in my opinion is that once you start pulling and your climbing rope is out of reach you have no good options if anything goes wrong and your rope doesn’t come down to you. As someone else mentioned, for a long approach with minimal rapping it may be viable, but in that scenario an Beal escaper would probably be better anyway. 

I was just on Royal Arches the other weekend and we used a 7mm 65m tagline. I probably wouldn't go smaller than 6mm as others have pointed out, it becomes a pain to pull, especially on low angle terrain. 

We used this setup youtu.be/dlKPQ_0f6aI?featur…

I've been playing with the dyneema tags for a few seasons now. Used to use 2.7mm, now using 1.75mm. Works great, mind you I've only been doing 30m rappels. Never flake it, either stuff it in a sack or stack it on the ground. 

A huge advantage dyneema has over accessory cord is that it doesn't stretch. It's easy to splice as well. Re pulling; in a reasonably clean rappel, with a lightweight rappel rope, it's not unreasonable to just pull it with your hands. If there's too much drag I put it on a carabiner with a munter and use the biner as a handle. As it's stronger than my body weight I don't have any reservations about pulling on it as hard as I can if anything were to get stuck. 

This has been the configuration I use. Some people don't like the clove onto the biner as a block but theres no knot to get sucked into the masterpoint which is nice. The pur line is a little goofy to rappel on but it's so durable; I've core shot my edelred rap line twice in the time it's taken to get the pur line fuzzy.

The best bend to join two ropes of unequal size is a double sheet bend.  If they're close or equal in size, then an alpine butterfly.

I'd hate to use bare dyneema as a tagline--it's just too slippery.  I have a piece of 6mm dyneema-cored line with a polyester/technora cover I use for toproping and rappelling.  I spliced an eye in each end, which means I don't have to tie line-weakening knots (the splice retains 90% of the line's strength), and I can join it to a thicker rope by passing an end through the spliced eye and tying a stopper, or just with a bowline.

Noah Gilbert wrote:

So you did a variation of a EDK and then stuck the biner through that? I was under the impression that you would do a stopper knot + biner block (say alpine butterfly with a biner) and then a double EDK (or whatever knot to join two ropes? with the second being opposite and apposed…

side question.. at what point does it become dangerous to join two differently sized ropes together, with EDK/flat overhand. I know hownot2 has some stuff in this, but it never really got in depth for me enough.z like let’s say I’m running a rope anywhere from 8.9-9.5, what’s the smallest diameter that I should go with in tagline if I decide to use the EDK method

Found the source I used:

https://sterlingrope.com/sterling-solid/when-would-i-use-a-tag-line?srsltid=AfmBOopdv4DeVSpqO7GkubtBeRNWGzj-l17RAOTNUf7u2YDZsKpVit3L

I don't know the strength of the knot, but it is only blocking, the tag line is not holding any weight in my case. 

I think my critera were: 

1. the climbing rope just needs to be blocked against the rap rings
2. the tag cord just needs to pull the climbing rope away from the backside of the rap rings
3. hopefully none of it gets hung up on the way down

Single Gibbs' knot seemed to check all three boxes.  I think I added the carabiner after the first rappel b/c the Gibbs got super cinched down (which was reassuring).

Disclaimer: Midwest Trad Dad having a Red Rocks adventure.

Eric D wrote:

I was just on Royal Arches the other weekend and we used a 7mm 65m tagline. I probably wouldn't go smaller than 6mm as others have pointed out, it becomes a pain to pull…

Did you block & single strand rap or rap both strands? I always use a 6.0mm APER (70m) for RA and rap on both strands, with a double biner in the ATC. 

As long as the first saddlebags the bottom half of each rope on their forearms, it should go very smoothly and then the second can zip their rap in less than a minute 

Back to the OP, I wish I could go lighter than 6mm but the mbs of 3-4mm just doesn’t give me the warm fuzziness of 5.5-6mm… I have a hard time overcoming the idea that I might be able to break it by pulling hard on a stuck rope, for example. 

I would argue that a beal escaper (or custom made) is safer than using a tag line under 5mm. They are more reliable to pull than a high friction rap with an ultra thin cord but the biggest thing is that you always have the lead line in your hand.

Given the topic here, it just occurred to me that the Anchor Extender I just had UIAA tested is made from Dyneema-cored 6mm rope.  If anyone needs a static 6mm tagline strong enough to rap single-strand (10kN), with spliced eyes in the end that retain full strength (knots weaken rope), I can supply any length up to 650 feet.

I hope to have a polyester/technora covered dyneema rope option on the market soon (I'm testing a prototype with a dedicated rappel plate for it), but the polyester covered one I have now, tested to UIAA 102, would make a killer tagline.  Glad to quote a price per foot if anyone DMs.