Rapping with a small diameter accessory line

I have a 70m 10.2 rope and I am looking for a thinner 70m rope to use for double rope rappels in alpine rock situations. Has anyone rapped with a 10.2mm and a 8mm at the same time, does the 8mm go through faster?
I don't want to go to twins or double ropes because I think they would be a pain to climb with and it would be best just to deal with a single rope while climbing and have the smaller coil packed away.
Any thoughts?

"1. The heavier rope will tend to slide down as you rappel, which can cause the ends to become uneven. The best way to combat this problem is to thread the heavier rope through the anchors, with the knot on the other side. That way, the anchor prevents the knot from sliding down the rock as you rappel. Of course, if you're doing multiple rappels and want to thread the ropes through each anchor as you pull them, this strategy will not work. After your first rappel, the lightweight line will come down first and when it is threaded through the anchor, the knot will end up on the other side."

Banks has some awesome advice.

I found his explanation of the above problem a little unclear if you are unfamiliar with the phenomenon, but his solution is absolutely correct.

Essentially, the thinner diameter cord will have less friction than the thicker, which will cause it to feed more quickly through the rappel device. As it feeds out unevenly, the thinner cord will have a tendency to travel through the anchor links and back down on the side of the thicker cord, causing the tails to become uneven(if you imagine tying into the thicker diameter rope with a bite and then lowering yourself out on the thin cord only, that is essentially what is happening).

The end result is that the thinner strand may not be a full 60/70m because part of it is running up through the anchor and back down again.

The solution is, as Banks said, to feed the thicker cord through the links so the knot blocks the rope from traveling.

I just wanted to make it clear that its is not a matter of the thicker cord stretching or sliding down, its an issue of the thinner cord traveling through the anchor, causing a shorter than 60 meter tail on the thinner side. I think that understanding will help you visualize and avoid this mistake.

And, the 2 big rules of rapping become even more critical when using disparate sized ropes:
TIE STOPPER KOTS ON THE TAILS AND USE A PRUSSIK BACKUP!!!

Cheers
Evan

Knots? I've used this setup numerous times with 9.2 lead and a 8mil tag. I tie the ropes together with two interlocking bowlines.

What about using an even skinnier (5mil) tagline and rapping solely on the fatter cord, the knot jammed in the anchor?

I have used a 10.2 and an 8 static a lot and it works really well. I use a figure 8 follow through knot with fishermans backups. A bit bulky, but I still have yet to have a rope stuck on me. I've never had problems with the 8 sliding faster, however I would recommend tying knots in the ends of both ropes regardless.

I find even a 7mm to be a pain in the ass with kinking.

Rappelling with an autobloc will help keep the smaller line from slipping through your belay device, but you will still have some slippage if the diameters of ropes are very different (10.2 and 6mm as an example). With an 8mm static cord I do not have an issue alternating the knot, but with a 6mm trail line you will want to always have the knot on the lead rope side unless you fix the smaller rope to the anchor below. Always pulling the skinny rope really sucks if you are using a 10mm lead rope.

For a super light hauling system try using a Tibloc and a DMM Revolver.

Kevin Stricker wrote:With an 8mm static cord I do not have an issue alternating the knot, but with a 6mm trail line you will want to always have the knot on the lead rope side unless you fix the smaller rope to the anchor below. Always pulling the skinny rope really sucks if you are using a 10mm lead rope.

Uhh, really? Do you mean you always want the knot on the lead rope side so its easier to pull the fatter lead rope? You might not need to pull it at all if the skinny rope goes through the anchor...!

As far as ease of pull, depends on the skinny rope. I use a 6mm static rope (kevlar) paired with either a 8.9mm Mammut or 9.4mm BW. Since my static skinny rope is kevlar, its pretty soft and not too hard to pull. I had a "personal alpine escape rope" or some such made by Esprite which was a 6mm rope and burly, but, had a real "bite" to it too, making it kinda hard to pull. If you got any slippage in your hand, it'd take a chunk of flesh with it. Durable and a nice cord. I miss mine (got chopped in a rock fall).

I find feeding a skinny cord out of some type of rope bag makes it much, much easier to manage. When I pull it, I pull it and stack it back in the rope bag.

Another thing I've noticed...if a 8.9mm rope paired with a 6mm cord, the knot tying them together can be really small. Small enough that I've had it pop through the ring on a rappel anchor (Guide's Wall in the Tetons). You can kind of "hold" the skinny cord a bit while on rappel and it kind of negates it running faster and pulling through a rap anchor. But, takes practise and I probably wouldn't recommend having to do it. Best to make sure your knot block is big enough, or, add a biner on a clove hitch (ie, a biner block).

I get a fair amount of use out of a "pull cord". Especially nice in situations where I'm not sure if I'll need to rappel full rope length or not, but, want to have that option and not have to hassle with twins and/or double ropes.

just out of curiosity, i usually tie a tripple fishermans knot for rapping, would this be an appropriate knot if using say a 9.5mm with a 7mm tag line? im guessing 8mm would work fine with this knot. are there any particular knots that work better than others when using a skinny tag line with a single rope?

max seigal wrote:just out of curiosity, i usually tie a tripple fishermans knot for rapping, would this be an appropriate knot if using say a 9.5mm with a 7mm tag line? im guessing 8mm would work fine with this knot. are there any particular knots that work better than others when using a skinny tag line with a single rope?

EDK for me.

I don't want that knot hanging up. Having to ascend my "pull cord" isn't an option I'd want to exercise.

When rapping on a single cord with a retrieval line, instead of relying on the knot to jam in the anchor -- potentially getting stuck in the anchors or accidentally moving through the anchor and dropping you into the void below -- try this:

1. Feed the rap line through the anchor and tie it to the retrieval line as usual -- I use an EDK.
2. Pull a few more feet of the rap line through the anchor and tie a butterfly right next to the joining knot
3. Attach a locking biner to the butterfly and then clip around the rap line on the other side of the anchor. Lock the biner. This creates a closed loop around the anchor with the rap line and prevents a the potential issues with rapping off of a jammed knot.
4. Rap on the a single line, while keeping the retrieval line close by -- hold it in your hand or have it slight through a carabiner on a gear loop, your pack, etc.

One thing I like about this is that as you pull the retrieval line, the locking carabiner pulls your rap line away from the rock helping to prevent it getting stuck on the way up.

BE SURE that the retrieval line is longer than the rap line unstretched (banks' 10 ft suggestion seems reasonable). If you let go of the retrieval in this scenario and the wind takes it away you have no way to pull your rap down!

I think I first saw this technique in Houston & Cosley's book on "Alpine Climbing".

B-rad wrote:When rapping on a single cord with a retrieval line, instead of relying on the knot to jam in the anchor -- potentially getting stuck in the anchors or accidentally moving through the anchor and dropping you into the void below -- try this: 1. Feed the rap line through the anchor and tie it to the retrieval line as usual -- I use an EDK. 2. Pull a few more feet of the rap line through the anchor and tie a butterfly right next to the joining knot 3. Attach a locking biner to the butterfly and then clip around the rap line on the other side of the anchor. Lock the biner. This creates a closed loop around the anchor with the rap line and prevents a the potential issues with rapping off of a jammed knot. 4. Rap on the a single line, while keeping the retrieval line close by -- hold it in your hand or have it slight through a carabiner on a gear loop, your pack, etc. One thing I like about this is that as you pull the retrieval line, the locking carabiner pulls your rap line away from the rock helping to prevent it getting stuck on the way up. BE SURE that the retrieval line is longer than the rap line unstretched (banks' 10 ft suggestion seems reasonable). If you let go of the retrieval in this scenario and the wind takes it away you have no way to pull your rap down! I think I first saw this technique in Houston & Cosley's book on "Alpine Climbing".

I've done this a few times, although not with a butterfly knot.

I think if you have an issue with a knot block getting stuck in the rappel ring, then you'll have an issue with a butterfly knot too. Its as small a profile or even more, so, IMHO, its actually a better chance of getting stuck.

Also kind of wondering if there's a better chance of your EDK tails getting tangled in the butterfly/biner combo too.

Tying the rope back can be a good idear if the pull is clear, but, its also someting else to get stuck on retrieval.

I think a clove hitch on a biner works better if you're concerned about your knot getting stuck in the rappel ring. And, if you use a biner on a quick draw, you can clip the other side biner on the draw back into the rappel line to accomplish the same thing you've outlined above.

The "closed loop" can be a good idear. I can think of at least one fatality concerning rappelling a single line from a block where the person wouldn't have died had they "closed the loop" like this.

Plenty of ways to skin this cat.

Cheers!

banks wrote:Stiles, Biggest problem with that setup is the tendency of 5mm cord to kink up and knot.

Agree. 6mm is as small as I would recommend but it is still quite prone to tangling if not careful. With skiiny ropes such as 6mm, rope management is very important. When coiling, I highly recommend "single strand" butterfly. That is, start at one end, coiling to the other end vs coiling from the middle or with both ends ("double stranded"). Treat it with a lot of care or you will cluster f@#k. Speaking from experience.

Difficulty pulling the ropes is also a concern with skinny cords. 5mm really cuts into the hands, especially if it is a tough pull.

banks wrote: I'd also be worried about the strength of the knot. If the thin cord got pinched off and eventually failed, it could cause the entire knot to fail as well - end result being: Climber FAIL

Disagree. When done properly, the breaking strength of the tag line is not relevant. That is, if you feed a few feet of the lead line through the anchor, then tie a good stopper knot, you could theoretically rap that single line safely without a tag line attached at all. The tag line and tag line knot are only there so you can pull the rope.

I routinely do this with a 6mm line and just about any lead line (9.4, 9.7 and 10.2). The only disadvantage is you can't alternate which rope gets feed through the next anchor (as Kevin Stricker metioned above). One the other hand, you never have to worry about the ropes creeping through the anchor resulting in unequal lengths.

edit: If you would like to close the system as others have mentioned, this can be accomplished very easy. The person NOT rapping first simply clips a sling from his belay loop to the stopper not while the first rappels. Then, when the first reaches the end of the rappel, he ties a knot in the tag line and clips it to his belay loop. With this method, the stopper knot is now backed up for both rappers.

Hmmmmm . . . I'll try out the clove hitch idea next time I'm at the crags and also evaluate the "stuck-potential" of the knots in different hangar types. So far I've had no problems, but as many know, complications only arise after a multitude of uneventful iterations. In addition, a clove hitch would be much faster to tie than the butterfly.

Great discussion fellas!

These are all great ideas for using a lightweight trail line. Just be sure that the difference between a "tagline" and a "retrieval line" is clear. Using an 8mm tagline is safe for rapping on both strands at once, since the 8 mil is presumably a fully rated rope. Using a 7mm retrieval line that is not fully rated as a climbing rope is unsafe to rap on.
Using this technique, we should always be tying a "closed loop" at the anchor w/ a butterfly and a biner, and rapping on a single strand, as b-rad states. Otherwise, we're just rapping on a cordolette.
Being extra careful not to spin in the air and potentially twist the cords at the knot is also important, learned from experience.
I generally only use a retrieval line as an emergency tool, if I know I'll be rapping a route, I'll bring an 8+ mil tagline.
This may be a bit redundant as a bunch of replies came through as I was writing, but these are good points anyways.

I dunno bout that Mike -- if cords are rated, the bigger problem is managing enough friction. You can get small static lines that have comparable strength to that of a climbing rope.

Greg D wrote: When done properly, the breaking strength of the tag line is not relevant. That is, if you feed a few feet of the lead line through the anchor, then tie a good stopper knot, you could theoretically rap that single line safely without a tag line attached at all. The tag line and tag line knot are only there so you can pull the rope.

Yeah...but...

One thing that makes me nervious about using a low strength static accessory cord, is, at 6mm, they start out at what? Around 1800 or so lbf breaking strength? Add a knot, and, reduce that by half. Then, rope gets stuck, you and a fairly burly partner pull for all your worth. I'm wondering, not likely, but, how close to busting that 6mm cord could you get? Especially if its been rubbing over sharp edges on retrieval and its damaged in a spot or two.

Always thought the perfect pull cord would be some of that high strength stuff. But, I sometimes rappel in combo with my pull cord through an ATC, and, the heat probably wouldn't be good for some of that high strength stuff. Which is why I really like the kevlar cord. Nice hand, soft, high strength and very high melting point.

Cheers,

Mike Soucy wrote:These are all great ideas for using a lightweight trail line. Just be sure that the difference between a "tagline" and a "retrieval line" is clear. Using an 8mm tagline is safe for rapping on both strands at once, since the 8 mil is presumably a fully rated rope. Using a 7mm retrieval line that is not fully rated as a climbing rope is unsafe to rap on.

I've seen awful messes from folks trying to use a "tag line" and/or a "trail line" for rappelling. Almost to the point where I'd say it wasn't safe to use for rappelling.

In these cases, the sheath and core were "hinky" and the trail lines sort of shrugged and twisted, becoming hopelessly stuck in an ATC. Particularly bad was the teal colored 8mm "trail line" which used to be sold by BD.

I can also imagine a 7mm static line, not rated for climbing, that would be perfectly safe to rappel on.

Below from Beal, on their current trail line:

TRAIL LINE 7,3 mm Dyneema

Hauling and abseiling cord.
Very light and very low stretch to facilitate hauling, and recovery of single rope abseils.

Warning : this an accessory cord which must not be used as a security rope. On abseils, it may be used as a pull-down line for an appropriately rigged single rope.
Weight : 30g/m
Strength : 1050kg
STRONG POINTS :
• Very static.
• Light.
• In 50 and 60 m lengths.
USES : Hauling and abseil cord.

The Dyneema which makes up the core of Trail Line and which makes it very low-stretch is extremely slippy. That’s why in use sheath slippage may occur. This may be eliminated by cutting the excess sheath off the end of the rope.

Yeah, in an ideal situation, 7mil cord has 2,000lb breaking strength.
But, when rubbing over edges, or when it has to be re-ascended or led on to retrieve a stuck rope, you're suddenly quaking in your boots.
When referring to a "tagline", all I mean is a fully rated climbing rope that enables you to rap full rope lengths on both strands safely.
Methinks we're talking about the same thing, just using different terms.

Mike Soucy wrote:When referring to a "tagline", all I mean is a fully rated climbing rope that enables you to rap full rope lengths on both strands safely.

This could mean any size of cord -- they are all fully rated to the strength that they are tested. though some companies test & use better materials than others.

As far as rappelling safely, you introduce more factors than just what the strength & size of the cord is.

When I rap with a 7 mil retrieval cord in the Tetons, I pre-rig my partners so that the ropes do not slip through the rings as I rappel with a third-hand backup. Before I pre-rig them, I tie my 7mil and 8.9 mil together with an EDK backed up with a 7 mil overhand, with a butterfly and locker above the EDK closing the lead-line loop. This set-up has proved to pull relatively smoothly and does pull the lead-line and EDK/butterfly/locker away from the rock, preventing snagging on edges and in cracks. After each rap, I pull the 7 mil, then thread the 8.9, untying and re-tying the butterfly/locker combo to close the next rappel loop, and repeat. Gloves and hand wraps are very helpful during this process. This set-up is ideal for alpine climbs where going light is beneficial.

However, I really like the idea of fixing the 7 mil while the second raps, then being able to thread the lead rope through the following anchor. This is equivalent to "managing" tension in the 7 mil pull-cord to prevent it from slipping through the anchor. Remember, you can always hold tension on one strand and let the other strand flow through your rap device. As long as the loop is closed and the climber cannot slip off the ends of the ropes, the7 mil retrieval system works quite well.