Skinny cords and rapping

[danmcph]

I read in Twights book about leading on a 9.4 and having a rap cord in the pack, like a 6mm. I would assume you would join them with an overhand knot.

 

My question is: How will it work on rappel? Will the skinny the difference between the 2 cord diameters cause the fat cord to have more friction so the knot migrates away from the anchor? My ATC says it is only good down to 7.5mm rope. Will this cause a problem, do I need to have a special belay device to do this? What else do I need to know?

[John Frieh]

I rap on a 9.2 mm and a 6 mm using a BD guide and though the knot pulls away from the anchor a little as you rap it isnt bad. The second just pulls the knot back to the anchor before he goes.

[cbcbd]

Skinniest setup I've used is 8mm with a 5mm. The knot does walk but I have not tested exactly how much it can walk, for obvious reasons.

 

No issues with my Petzl Reverso.

 

Most cases you can setup the rap so the knot jams at the rappel anchor point preventing it from moving, with the knot on the skinny-rope side. If you're rapping off chains it will jam easy, if you're making your own anchor just tie a small anchor point (overhand on a bight) with the sling. With V-threads on ice I just thread the ropes through it and the knot jams against the screw hole naturally.

 

The biggest issue with skinny ropes is tangling. Excellent rope management is a must unless you want to waste a lot of time undoing a rat's nest.

[psychobikere]

Call me ignorant, but up until now I have always climbed on single ropes and brought a second rope for raps. I am considering trying this system out and getting a skinny line in lieu of the second rope. Anyone have any specific suggestions for a skinny rap line?

[John Frieh]

Anyone have any specific suggestions for a skinny rap line?

 

The lightest 5-6 mm one you can afford. Purchase ~5 meters longer than the rope you lead on so that even though the knot will move during rap you still hit both ends at about the same distance. Also if needed one can cut pieces off the rap line for rap anchors in a pinch.

[psychobikere]

I am assuming that will be enough extra distance to cover for rope stretch also?? Are there any advantages to one type of cord over another?

Thanks.

[Jon H]

Esprit Ropes of Canada makes a 6mm static line called the Alpine Escape Rope that is very popular for this exact purpose. Last time I looked it wasn't listed on their website, but if you called up they had no problem talking about it. Colin Haley, Mikey Schafer, and plenty of other hard alpine climbers use it. If you do a search for it here on CC, you'll find it discussed quite heavily.

[Maine-iac]

interesting write up, with some good pictures, about this topic in accidents in north american mountaineering. make sure to have this one figured out before weighting it in real life.

[Buckaroo]

Maxim Tech Cord. (also sold as BD Gemini) 5mm "Technora" is the strongest but it loses a lot of strength with knots and with repeated flexing, like going through a friction device.

 

If you tie a knot that can't slip through the anchor then you rap on your lead rope as a single and just use the 5mm for retrieval.

 

the Tech Cord is really stiff and acts like a cable and doesn't tangle very easily.

 

you can add more friction with two beaners on your ATC or run through another beaner clipped to your gear loop

 

There's also the Buggette that fits a 5mil line. I've done some climbs where I just needed a rap line to descend and used the 5mil Tech cord. 60M only weighs 3 lbs 4 oz.

[pcg]

There's also the Buggette that fits a 5mil line. I've done some climbs where I just needed a rap line to descend and used the 5mil Tech cord. 60M only weighs 3 lbs 4 oz.

I've tried a Buggette and find it offers no more friction than an ATC Pro. Even stacked with the ATC I wish I had more friction for rapping on a single 8mm Beal. I can't imagine rapping off single 5mm with a Bugette unless you are using an auto block or something and then it would be awfully jerky, or do you just wear gloves and burn 'em up?

 

Edit: Ok I went back and re-read your post and noticed what you said about adding more friction. I'm leary about deviating from setups that are tried and proven and have never heard of adding friction by running the rope through something attached to a gear loop, but it sounds like something worth trying and so I'm going to play around with it and see how well it works and how robust the system is. Will probably try a brake bar on a biner as well.

Back in the day I used to rap off skinny single rope with just a biner w/brake bar attached to a diaper sling and then passing the rope around behind my waist and wearing gloves. I usually jammed an old towel behind my waist as well or the rope would burn a mark on my jacket. Gloves burnt too. This was common practice. Funny thing is I felt totally safe back then. Not any more. Modern rappel devices and autoblocks are sooooooooo much safer. No going back.

 

BTW a monster Munter works great for rapping off single 8mm except it is brutal on the rope and so I would only use it in an emergency.

Edited August 28, 2011 by pcg

[pcg]

interesting write up, with some good pictures, about this topic in accidents in north american mountaineering...

What year?

[Maine-iac]

Current one-2011. 12 people died in 2010 because of a rappel error.

[DanielHarro]

6mm mammut tech cord!

[catbirdseat]

I remember Colin saying or writing something about rapping on 5.5 mm cord on Nanga Parbat, or somesuch. We need to get him to weigh in. The canyoneers are really the experts when it comes to raping on a a single strand. For some reason they prefer it. I think it is mainly because they like figure eights.

[dberdinka]

Whoa! This thread strikes me as being highly dangerous.

 

So danmcph there are two ways you can use a skinny cord for rapping.

 

1) actually rap on it as seems to be advocated here.

or

2) use it only as a pull line to retrieve your main rope.

 

Either method can get you killed but I argue the 1st is far more dangerous.

 

So unless you are....

 

a) Climbing Nanga Parbat

b) <=23 years old

c) or going through a divorce

 

....you might want to avoid actually rappelling on something as skinny as 5 or 6 mm.

 

Here are two other threads and some outside links on the subject

 

Rappel Cord?

 

50 Meter Skinny Rope

 

How to set up pullcord rappel

 

Tutorial on carabiner blocks

 

As far as the actual skinny rope goes I'm really happy with my Imlay Pull Cord.

 

It's light (so I bring it)

stiff (so it doesn't tangle)

very static (so it's easy to pull)

durable and cheap.

[JasonG]

Thanks for reviving those threads Darin, good stuff. Do you use a rope bag with your skinny, or just toss it typically? Ever had much trouble with all the knots and biner jamming in cracks? Certainly seems attractive to lead on a single line rather than twins or half ropes.

[dberdinka]

Good point. I do use rope bags and unfortunately there is nothing out there commercially available that really does the trick.

 

Fortunately I like to stay up late at night sewing things so I've made my own. They're light, stay open on there own, fold into a pocket and are set up with an adjustable strap for easy stacking.

 

Maybe I should post a diagram. I'm curious what others do....

 

 

I have had the whole clipped-together-for-backup assembly hangup while rapping a wall and it's no fun. If the rap ring is small and solid and your blocking biner is big and thick do just a carabiner block to avoid potential headaches.

 

 

Again be very careful. If you were for some reason (and there are reasons) doing this set up with a single rope it's easy to rap on the wrong end which would quickly lead to....death.

[pcg]

If you were for some reason (and there are reasons) doing this set up with a single rope it's easy to rap on the wrong end which would quickly lead to....death.

Why would you not stay in the habit of tossing the skinny and rapping on both so the "right end" will always be clipped.

Edited September 2, 2011 by pcg

[Wastral]

Ok, it works like this. 2 people.

 

1st guy down goes down the big line. 2nd hold knot from moving if needed.

 

1st guy down take end of small line and ties it off(bight through biner to a piece of pro) is sufficient typically can do figure 8 as well as its safer but harder to untie.

 

Note 1st guy down typically MUST carry the rack to tie off small line.

 

2nd guy down rappels big line.

 

Pull small line.

 

This is if you are not sure that the knot will not go through the rappel anchor or if you have insufficient sling material to create a proper anchor etc.

 

Just an FYI. Quite often when doing this I don't even bother to watch the anchor but as rote simply tie off before 2nd comes down. A whole pile of hard yanks lets the 2nd know bottom guy has it tied off.

 

PS. For small line non tanglements when throwing. A throw bag from Silnylon is wonderful. Or conversely the 1st guy down can simply carry said throw bag and let it uncoil out of bag if its lower angle stuff. This method is HIGHLY recommended.

Edited September 2, 2011 by Wastral

[genepires]

If you were for some reason (and there are reasons) doing this set up with a single rope it's easy to rap on the wrong end which would quickly lead to....death.

Why would you not stay in the habit of tossing the skinny and rapping on both so the "right end" will always be clipped.

 

Just a theory to answer your question. The skinny ropes are more susceptable to being cut over edges. It seems like every rap involves the rope laying over some kind of edge. With time, the probability is high that your skinny rope will cut taking you down. If you are lucky, the rope knot will jam and you can single rope rappel down but without a means to retrieve the rope.

 

PLus then there is the unequal rates of flow of rope through the rappel device which causes the ends to not be even and the possibility of burning the rappel anchor webbing if there is no metal rings.

[G-spotter]

Or you could just climb on double ropes and never have to worry about this retarded skinny rap cord management

[rob]

can I "like" this comment?

[Wallstein]

Dru, you've got the right answer unless that is of course if you plan on having the second jug or on hauling a pack.

 

Every rope system has its pro's and con's and its all about knowing how and when to use each system.

[Sean_T_Stevenson]

I have done this when I want to use all 60m of my single for a double-length rappel, but I'm really only using the skinny for rope retrieval. I use a 5mm cord the same length as my single (60m). I setup the rappel with the joining knot on the small cord side of the anchor. I put an in-line eight knot in the large single just behind the joining knot (still on the recovery cord side) and clip a locker into it, then clip that around the large single rope on the opposite side of the anchor. Then rappel down the single as a single - the knot will jam against the anchor. I weight the recovery line just to minimize the jamming against the knot so it isn't too hard to retrieve, but even if you don't weight it at all, the locker prevents system failure. Worst case scenario - the knot slips through the anchor, basically seizing to the anchor because of the in-line eight / locking carabiner. In that case, you still have a full strength single to ascend to sort it out. Otherwise, pull on the retrieval line, and the whole thing should feed easily.