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TR Solo with Prusik-tending Pulley


Original Post
David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 124

It's interesting to watch arborist videos because they have a lot of the same problems that rock climbers have, but arborists often solve those problems differently. Watching this video, he basically builds a progress capture system out of a Prusik and a normal (non-progress-capture) pulley.

This got me thinking. The thing I use progress capture pulleys the most for is TR solo. If I'm relying on a progress capture pulley to catch me, I want a backup, so I use a second progress capture pulley (Micro Traxion is the first, Roll N Lock is the second). But what if I could use a Prusik with a tending pulley to back it up?

There's some history of using Prusiks for TR Solo. The problem Andy Kirkpatrick notes is that Prusiks slip and melt, but this problem can be solved by using a modern aramid-fiber cord (I use an aramid fiber Hollow Block anyway). The other problem is that tending the Prusik can be a pain, but if you put your motion capture pulley below the Prusik, the motion capture pulley can tend the Prusik for you!

This ends up looking like this:

This is far simpler than any other TR solo setup I've come across. Other systems require either some elastic to keep the top device up, or two separate strands, so the two devices don't interfere. But in this case we want the devices to interfere.

The feeding aspect of it works perfectly--if I disengage the progress capture pulley and yank on the Prusik, it tightens and becomes hard to feed rope through, but that should never happen because the Micro Traxion should always catch first (and if it doesn't, you want the Prusik to tighten). It seemed to feed equally well with the Roll N Lock instead of the Micro Traxion.

My main concern with this setup is that if the Micro Traxion fails, the Prusik might slide too much. I'm going to take some falls on just the Prusik (with a TR backup) to see how it behaves. But other than that, this seems like a really clean system.

Anti-cross-loading carabiners would probably be a good idea here.

Any ideas on how this might go wrong?

To be clear, I'm not looking for advice on other TR solo setups. I am looking to discuss this setup. I already have a tried-and-true TR solo setup that works for me, and I probably won't start using this one any time soon.

Kevin Mcbride · · Canmore AB · Joined Jan 2017 · Points: 160
David Kerkeslager wrote:

It's interesting to watch arborist videos because they have a lot of the same problems that rock climbers have, but arborists often solve those problems differently. Watching this video, he basically builds a progress capture system out of a Prusik and a normal (non-progress-capture) pulley.

This got me thinking. The thing I use progress capture pulleys the most for is TR solo. If I'm relying on a progress capture pulley to catch me, I want a backup, so I use a second progress capture pulley (Micro Traxion is the first, Roll N Lock is the second). But what if I could use a Prusik with a tending pulley to back it up?

There's some history of using Prusiks for TR Solo. The problem Andy Kirkpatrick notes is that Prusiks slip and melt, but this problem can be solved by using a modern aramid-fiber cord (I use an aramid fiber Hollow Block anyway). The other problem is that tending the Prusik can be a pain, but if you put your motion capture pulley below the Prusik, the motion capture pulley can tend the Prusik for you!

This ends up looking like this:

This is far simpler than any other TR solo setup I've come across. Other systems require either some elastic to keep the top device up, or two separate strands, so the two devices don't interfere. But in this case we want the devices to interfere.

The feeding aspect of it works perfectly--if I disengage the progress capture pulley and yank on the Prusik, it tightens and becomes hard to feed rope through, but that should never happen because the Micro Traxion should always catch first (and if it doesn't, you want the Prusik to tighten). It seemed to feed equally well with the Roll N Lock instead of the Micro Traxion.

My main concern with this setup is that if the Micro Traxion fails, the Prusik might slide too much. I'm going to take some falls on just the Prusik (with a TR backup) to see how it behaves. But other than that, this seems like a really clean system.

Anti-cross-loading carabiners would probably be a good idea here.

Any ideas on how this might go wrong?

To be clear, I'm not looking for advice on other TR solo setups. I am looking to discuss this setup. I already have a tried-and-true TR solo setup that works for me, and I probably won't start using this one any time soon.

I'd hate to sound cliche, but yer gonna die.

Ben Stabley · · Portland, OR · Joined Sep 2014 · Points: 167

From my armchair, I'd guess my main concerns would be 1) the prusik getting caught up in the micro traxion, 2) prusik being too grippy for the micro traxion to push easily, therefore the system impeding your climbing, and 3) the pruisk engaging before the micro traxion during falls. However, it seems like those are not issues from your initial testing.

Looks cool, and I'd be interested to read your findings after further testing.

r m · · Unknown Hometown · Joined Apr 2015 · Points: 0

Interesting idea. When you say the feeding works perfectly, does that mean it travels up the rope smoothly?

SW Marlatt · · Arvada, CO · Joined Feb 2006 · Points: 50
wivanoff · · Northeast, USA · Joined Mar 2012 · Points: 553

Year ago, Robbins published the "Barnett System" for self belay in Advanced Rockcraft.  It was very similar to what you are advocating but without the mechanical progress capture device. So maybe more similar to what is often shown on arborist sites.

IIRC, someone fell, melted the friction knot and was either injured or killed. It may have been lead climbing - I really don't remember but it was discussed on rc.com

Dunno. I've used a single spring loaded Gibbs Ascender for many years. Like you "I already have a tried-and-true TR solo setup that works for me, and I probably won't start using this one any time soon."

David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 124
r m wrote:

Interesting idea. When you say the feeding works perfectly, does that mean it travels up the rope smoothly?

Yeah. I was surprised how well this worked when I tried it.

Brocky · · Unknown Hometown · Joined Jun 2016 · Points: 0

You could simplify your system by using a double eye hitch cord and attach the Micro and hitch to the same carabiner.  If the hitch cord eyes were tight it would also help with the side loading of the carabiner.  There are dozens of friction hitches that would work better than the Prusik hitch.

When testing the hitch, maybe just disengage the cam and see if consistently grabs after the pulley pushes it up.  Ben's third concern above about the hitch grabbing before the Micro would actually be a good thing, rope on rope is much better than the shredding teeth. If your hitch always grabs, and there should be very little slack, there's little chance of burning the rope.

SWMarlatt, great hitch you came up with, an Autobloc, with a bottom booster!  I used it for a while, and you're right, it must be tied just right to both grab and slide easily.  You say Gary came up with the name, did you name it something else?

David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 124
wivanoff wrote:

IIRC, someone fell, melted the friction knot and was either injured or killed. It may have been lead climbing - I really don't remember but it was discussed on rc.com

The story I've heard is that it was lead climbing. In any case, I don't think melting is a problem with aramid fibers. They burn before they melt, and do so at very high temperature--firefighters can wear equipment made of aramid fiber.

David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 124
Brocky wrote:

You could simplify your system by using a double eye hitch cord and attach the Micro and hitch to the same carabiner.  If the hitch cord eyes were tight it would also help with the side loading of the carabiner.  There are dozens of friction hitches that would work better than the Prusik hitch.

Yeah, I've considered this, it seems like most arborists are using these. The VT Prusik seems to be the eye-loop equivalent of the hollow block, made with aramid sheath to prevent melting. It's slightly thicker (making it less likely to jam in the pulley) and the eyes allow you to use an asymmetric Prusik.

When testing the hitch, maybe just disengage the cam and see if consistently grabs after the pulley pushes it up.

It catches nicely in a living room test, but I haven't tested it with bodyweight; I'm going to do that (with a TR backup) later today.

Ben's third concern above about the hitch grabbing before the Micro would actually be a good thing, rope on rope is much better than the shredding teeth.

Agreed, but the geometry of the setup is such that I haven't been able to get the Prusik to catch first without completely disengaging the cam. With the cam engaged, the Micro Traxion always catches first.

I'm pretty okay with that, though--I've been using the Micro Traxion as my primary rope solo device for a while and taken lots of falls on it, and never had any rope damage.

eli poss · · Durango, Co · Joined May 2014 · Points: 487

I've also tried this, although with accessory cord rather than the hollow block and a minitrax instead of a microtrax. I couldn't get the prusik to slide easily so eventually just gave up. Also the prusik would sometimes interfere with the minitrax and it appeared to get sucked into the minitrax, although that never compromised the security of the minitrax in my limited testing.

I would say, if you can get it to feed easily and you can be sure it won't interfere with the microtrax, then go for it. I like the idea of a friction hitch above the trax because, if you happen to thoroughly fuck up so bad that the trax somehow shreds the sheath, you might still be caught by the hitch above the coreshot section. 

eli poss · · Durango, Co · Joined May 2014 · Points: 487
SW Marlatt wrote:

I haven't been able to test this puppy outside of my closest, so I'm curious to see if it will feed smoothly like minitrax. When I TR solo, I usually weight the bottom of the rope and girth hitch a loop of bungee cord through the clip in point and loop it over my head.

For this, I could clip the bungee cord to the locker and loop over my head but I'm not sure if will have the same effect. I was hoping you might be able to provide some insight into this.

David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 124
eli poss wrote:

I've also tried this, although with accessory cord rather than the hollow block and a minitrax instead of a microtrax. I couldn't get the prusik to slide easily so eventually just gave up. Also the prusik would sometimes interfere with the minitrax and it appeared to get sucked into the minitrax, although that never compromised the security of the minitrax in my limited testing.

I'm guessing here, but I think the interference might be a function of the size of the Prusik in relation to the pulley. I'm not sure how thin your accessory cord was, but the Hollow Block is fairly wide (6.8mm) so it doesn't fit into the top of the pulley. The VT Prusik used by arborists is even wider (8mm) and they have a tending pulley (which has a "rail" that prevents friction knots from entering the pulley). This might be why it didn't work as well.

It's worth reiterating that friction knots melting during a fall has caused accidents (though details of these accidents are vague), so an aramid-fiber Prusik (which won't melt) might be important.

I would say, if you can get it to feed easily and you can be sure it won't interfere with the microtrax, then go for it. I like the idea of a friction hitch above the trax because, if you happen to thoroughly fuck up so bad that the trax somehow shreds the sheath, you might still be caught by the hitch above the coreshot section. 

I guess that's the ideal, but given the Prusik will might slide a bit, it's possible that the Prusik would cinch around the coreshot section. That said, a) the Micro Traxion has never so much as visibly frayed my sheath, and b) this would be true of a mechanical backup device as well--which would possibly be more disastrous, since the tooth/cam would be closing on the core. It basically seems like this is a potential problem for all single-strand setups.

EDIT: One thing that I noticed when testing this is that when the Micro Traxion cam is locked open, the rope can at certain angles still slide across the teeth. Since there isn't enough pressure for the teeth to catch, they just tear through the outer layer of sheath. This might be a reason to switch away from a toothed device for this kind of setup, to something like the Roll N Lock. The cam should never be locked open during climbing, but I could see situations where one might want to throw a rappel device above the Prusik, unlock the cam on the progress capture device, and rap down without completely removing the progress capture device.

Gunkiemike · · Unknown Hometown · Joined Jul 2009 · Points: 2,795

Eli - I think you'll be MUCH better off teaching newbies to prusik up the rope rather than that dodgy self belay set-up.  Easier to remember, more widely applicable to other SR situations, field-proven (aren't you worried even a little bit about your liability exposure if one of your students gets hurt trying what you tried to teach them?), and more versatile in terms of what slings/cords they may actually have with them.  

Also - whatever concern you have with the rescuer weighting the rope is going to be magnified if/when the rescuer in your proposed scheme slips and falls onto it.  The leader has fallen and the top pro was solid enough to catch them, right? The static load of the immobile leader and the gently prusiking rescuer is far less than what the gear was just exposed to.

Kyle Tarry · · Portland, OR · Joined Mar 2015 · Points: 175
eli poss wrote:

So I'm teaching a climbing class next fall and am currently writing a curriculum to provide a foundation to enter into the world of multi-pitch trad climbing and associated self rescue. In thinking about teaching self rescue for the worst case scenario (unresponsive leader who cannot be lowered back to the belay) I've decided to teach TR soloing instead of jugging while hanging on an unknown piece. In theory, the climber is on easy terrain or uses french free or aid to avoid weighting the rope, but has a TR solo set up just in case. 

My issue was that, while I choose to carry a mini-trax on my harness, most people don't and I want to teach a method of TR solo that can be easily improvised with what a multi-pitch trad climber is likely to have on them. I'd read about your modification to the helical a few years back but couldn't ever figure out how to tie it from the single photo and vague description available on Storrick's site.

But, after experimenting and tinkering for about an hour, I found a way to tie the hitch so that an upward pull on the locker slides the hitch up easily. I'm assuming I just found the modification that you made, but I'm having a hard time determining if it is the same thing that's in the photo on Storrick's site. So I took pictures of each step after tying the single strand version of an autoblock (which I think is the helical but I'm not sure) and the final product.

Why not just teach the standard method of self-belay on a rope using 2 friction hitches, as taught by every basic text and class, used in crevasse rescue, emergency rope ascension, etc.?  Just use prusiks (or whatever hitch is applicable to your cord or slings on your harness) and slide them as you go.  There is no need to have a perfectly smooth feeding system for the very rare leader rescue scenario, which isn't a normal TR solo situation.  Teaching students a special, different, unique way of doing it for this rare situation doesn't make a lot of sense, just use the standard tools everyone should have in their standard toolbox.

(Not to be a jerk, but you should consider whether you are qualified to teach a bunch of, presumably beginner, climbers self-rescue techniques in an official capacity).

Sorry, /threadjack

Brocky · · Unknown Hometown · Joined Jun 2016 · Points: 0

That's not the Marlatt, eli. To tie, it is simply an Autobloc with the bottom eye having an extra long tail.  You tie another eye with this tail, leaving enough cord between the bottom eye and this eye to wrap around the rope it and clip to the carabiner under the other two eyes. The cord wrapped around the rope under the hitch from the added eye helps to push up the hitch.

I've got no problems with toothed ascenders, I currently am using a Croll that pushes up a hitch to climb trees.  The Asymmetrical Prusik is better than the Prusik, but not by much.  I would think a Michoacán would work better because the eyes come out of the bottom of the hitch on each side rather then together.

The bottom one the Michoacán, the top the Marlatt with tied eyes, and with spliced or sewn.
eli poss · · Durango, Co · Joined May 2014 · Points: 487

David, the cord was 6mm and I think the microtraxion also has a more narrow opening than my minitraxion so that is probably why your set-up fared better than mine.

About the marlatt knot, and TR soloing, the whole point is to avoid all of the bouncing around and possible cyclical loading associated with jugging because the belayer doesn't know the quality of the piece.

And yes, I am qualified considering I am TAing the class and my knowledge expands further than the overseeing professor. And I won't be teaching beginner climbers 

Kyle Tarry · · Portland, OR · Joined Mar 2015 · Points: 175
eli poss wrote:

And yes, I am qualified considering I am TAing the class and my knowledge expands further than the overseeing professor. And I won't be teaching beginner climbers 

The fact that you are a TA, and the fact that you know more than the professor, don't make you qualified to teach self-rescue.  Beginning climbers or not, you said it's a foundation class for "entering the world of multipitch", which implies that the students don't have these skills already, which makes them, effectively, beginners in this realm.

I won't continue to harp on this, but this seems like a huge amount of hubris coupled with a large liability.

eli poss · · Durango, Co · Joined May 2014 · Points: 487
Kyle Tarry wrote:

The fact that you are a TA, and the fact that you know more than the professor, don't make you qualified to teach self-rescue.  Beginning climbers or not, you said it's a foundation class for "entering the world of multipitch", which implies that the students don't have these skills already, which makes them, effectively, beginners in this realm.

I won't continue to harp on this, but this seems like a huge amount of hubris coupled with a large liability.

Once again, not beginners, and the class isn't a foundation for entering the world of multipitch. I'm just creating a curriculum for more advanced students who progress through the earlier content (basically an SPI equivalent) more quickly. If time allows the class to progress that far, student will already have experience with leading on gear, and all of the self rescue content covered in the SPI course. 

David Kerkeslager · · New Paltz, NY · Joined Jan 2017 · Points: 124
SW Marlatt wrote:

It should be obvious that you want to use this, or your pully method, with a very strong, stout steel biner, since there is a possiblity of loading it in weird ways.

Is there any reason a belay biner (designed to prevent cross-loading) couldn't be used for this? There are a bunch out there (here or here are two different styles).

I'd also suggest a second TR that you tie into occasionally, using a clove or loose 8-loop.

The current method I use is two strands, one device on each strand. I don't use backup knots because I feel two strands, two devices, etc. is redundant enough. Everything is doubled.

For people who use a single device on a single strand with backup knots, do you tie the backup knots in the same strand? How, given the strand has to be weighted a bit? Or, do you have a second strand? Doesn't a second strand defeat the purpose (at that point, you might as well have a second device so you don't have to stop to tie knots).

Brocky · · Unknown Hometown · Joined Jun 2016 · Points: 0

Where are you going to place the Mini with the three eyes of the Marlatt?

Guideline #1: Don't be a jerk.

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