Proposal to Reduce Blake's Hitch Friction Damage

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18 years 4 months ago - 18 years 4 months ago #123301 by jimk123
The purpose of this entry is to discuss the Spider Rappel and to present it in a novel application for a descent on a dynamic climbing line system. The Spider Rappel is a self-belayed descending system with the benefits of reducing Blake’s Hitch friction damage, minimizing the load pressure to lower the knot, and providing a smoother descent. In the simplest terms, it transfers your weight from the Blake’s Hitch to a descending device. The hitch serves to lock off the descending device until your hand moves the knot down. Though the mechanics of descending with a Blake’s Hitch remain unchanged, you can’t ascend with this configuration. However, there are two extreme descending circumstances that would warrant its use: 1) partner rescue 2) anticipated rapid exit of the tree. In general usage, it could be employed following the apex of any climb for the purpose of reducing friction damage to the rope on descent.

The Spider Rappel is cited in only a few climbing publications as a technique that eliminates the safety concerns found with the conventional rappel and the traditional self-belayed rappel systems . The presentation of it here for a dynamic climbing line system is for your evaluation and feedback on a “low and slow” basis. It’s unknown if this adaptation to a dynamic climbing line system has been employed or published. Because the dynamic climbing line system is self-belayed, the safety risk of trying this is minimal. It’s more of a question if this is practical for tree climbing. Your feedback is welcomed.

Publications on the Spider Rappel describe its use on a static line application. In a nutshell, the configuration is the reverse order of the self-belayed rappel. The rappel device is connected to the climber with an extended loop, placing the final attachment to the rope well above head height. The friction hitch (Prusik in this application) is shortened and placed beneath the rappel device – at chest height. Hence, this is the reverse of how things are taught. For those in possession of Jepson’s “The Tree Climber’s Companion” 2nd edition, regard the Figure-8 Descent figure on page 65 and imagine the reversal of the figure-8 and the Prusik knot locations. There are several benefits to this “spider” configuration. Descending devices are pinch points. They will eat hair, shirts, gloves and the fingers within. Placing the descending device above the climber’s head eliminates that. Also, the Prusik knot can lock-up when substantially loaded. Prusiks have melted under rapid descent conditions when positioned above the descending device, where the load is the heaviest. When employed in the “spider” configuration, the Prusik doesn’t lock up and friction concerns are minimized. Because the Spider Rappel moves the climber’s weight from the friction knot to the rappel device, it’s regarded as a rappel configuration for a partner rescue. Moreover, your partner is attached directly to the rappel device, and thus the additional weight is on the device, not your harness system.

Having described what a published Spider Rappel configuration looks like, the core of this entry is concerned with adapting the “spider” configuration to the dynamic climbing line system for tree climbing applications. The modifications are simple. Begin with your usual doubled rope over a tree crotch system, connected by a Blake’s Hitch (Jepson page 53, 83). Using an extended loop from your harness, attach the descending device to a place on the rope above your head - on the running end of the climbing line. If you attach it to the working end, it hangs there and provides does nothing. The descending device could be a Munter Hitch on a pear shaped double locked carabiner (Jepson page 81) or a standard figure-8. The true advantage of this “spider” configuration is to minimize rope wear. Thus the figure-8 would be preferred over the Munter Hitch.

My evaluation on a dynamic climbing line system (Jepson page 64) indicated that the “spider” configuration on a descent reduced the load on the Blake’s Hitch while holding the climbing position steady. Your experience, evaluation and feedback will be the final judge if the benefits of reduced rope wear are worth the effort of using this system. For sure, we want to highlight any perceived weaknesses.

As a final comment, evaluation of the Spider Rappel technique in general would be interesting on the merit that that it has the potential to replace the traditional self-belayed rappel technique.

Regards,
JimK

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18 years 4 months ago - 18 years 4 months ago #123302 by jmaher
Most of my climbs are solo wilderness climbs. When climbing solo in remote areas I am a bit more cautious than when climbing a tame tree in the city park. Because of this I have begun using a system similar to this that I learned from climbing friend and fellow climber Bob Wray this past autumn.

The system that I am using for descent on a double rope system involves clipping a mini-rack to the delta on my New Tribe harness and running my "down rope" through this descending device. I keep one hand on the down rope beneath the descending device and place my other hand on the Blakes hitch and pull it down.

Once my load is on the rack, rather than on the Blakes hitch, I will loosen the knot slightly to reduce friction within the knot and begin my descent while keeping slack in my climbing bridge. This reduces friction within the Blakes hitch and allows a smoother and more speedy descent than could be done on the Blakes hitch alone.

In addition to reducing friction within the Blakes hitch the system provides a safety back-up to the rappel rack. If I were to completely release the rope with both hands, the Blakes hitch would set itself and protect me from a fall without the problems that arise when the same thing happens on a standard SRT rappel. I have tried this several times and it has never failed to bring my descent to a halt.

While I am using a four bar mini-rack, any standard descending device would work in its place. I have tried doing this with a Petzl Grigri, but I have found that in order to descend efficiently, I need three hands---one to mind the Blakes hitch, one to operate the control handle on the Grigri, and another hand to hang onto the down rope.

Bob Wray is the only other climber I know who is using this system. When I saw it for the first time I was immediately impressed with the safety features that it offered to me as a solo wilderness climber. I now use it regularly when I climb alone.

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18 years 4 months ago - 18 years 4 months ago #123303 by jimk123
As an example of why this system needs your evaluation, I discovered a flaw with the above “spider” configuration on the DRT. Under certain the conditions, the descending device can advance down on the Blake’s Hitch, disabling the entire system. Imagine a 140 pound climber with 230 pound partner in a rescue. There’s a chance of the descending device being pulled into Blake’s Hitch. In this configuration the descending device is on an extension from the harness and has a range of movement independent of the Blake’s Hitch position.

This problem is resolved by anchoring the descending device into the working end above and out of reach of the Blake’s Hitch. The simplest configuration would be a carabiner attached to the working end with a Clove hitch. The same carabiner is then used in a Munter Hitch with the running end. The result is a configuration that takes the load off the Blake’s Hitch, reducing friction damage to the rope. There’s a gain in efficiency with this modified set-up. The carabiner on the working end can be anchored in position before the ascent. With one quick Munter Hitch to the running end, the “spider” descent system is in place. In a similar fashion, it can be easily removed from the running end for the next ascent.

The objective here is to reduce friction wear induced by the Blake’s Hitch and to extend the safe working life of your rope. Hopefully this “spider” modification fulfills that objective and adds control to the descent process. Your “low and slow” test results are welcomed. It will be interesting to hear about other variations to the configuration. Consider what the possible dynamics are with a climber under 80 pounds. Would the Blake’s Hitch set in this proposed “spider” configuration where weights are low? The mechanics of the system are unchanged; the distribution of weight on the rope is different.

In response to jmaher, do you see any issues on attaching the rappel device to the working end versus the delta on the harness?


Regards,
JimK

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18 years 4 months ago - 18 years 4 months ago #123304 by Tom Dunlap
This problem is resolved by anchoring the descending device into the working end above and out of reach of the Blake’s Hitch. The simplest configuration would be a carabiner attached to the working end with a Clove hitch

Help me here, I'm having a thick-headed moment. What do you mean by the "working end" of the rope? In a DdRT system one end is on the ground, the running edn, and the other comes down from your TIP to the saddle, becoming the workng end.

I've thought about this a little now. Do you advise using the end tail of the rope that comes out of the climbing hitch?

I have some comments about your setup but 'll wait until I have a clear vision in my head about your setup.

Have you done any reading about "backing up rappels" ? There have been many studies about the system. The problem with one of the parts releasing the other part is one of the biggest issues with a backup. A proper backup needs to be rigged so that it can never interfere with the primary device.

Instead of a backup, consider using a Petzl I'd. The I'd is rated as a two person load device. Have you used one? They are really nice! Don't get bogged down on the cost, lets talk about function first.

Tom

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18 years 4 months ago - 18 years 4 months ago #123305 by icabod
I've used an 8 below my blakes for several years when doing solo climbs, or after a long climb and my hands aren't working as well as I'd like.

The system is as Joe described. It works very well.

Abour the spider system I would only have a concern that an 8 above my head would mot be tended well and might get girth hitched. I've seen this happen to the careless while on rap, and it is not easy to resolve, though with a blakes below climbing back up to get to the problem would be somewhat easier.

Only problem I've had using the 8 on descent is the wicked twist I get in my Yale XTC. It dosen't twist in the bag when I'm putting it away, but just as soon as I redeploy the thing kinks. Not fun.

Climb Safe!

Icabod

Cam "Icabod" Taylor

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18 years 4 months ago - 18 years 4 months ago #123306 by jmaher
Like Tom, I am a bit confused about what we are talking about here. On my DRT system I refer to the rope passing through the Blakes hitch and on down to the ground as the "down rope". That terminology comes from hanging out with Abe Winters. Is this what we are tying the descending device to? If so, I am having a very hard time trying to visualize what is going on here. Since we don't seem to have an established terminology that we are all agreed on please describe in more detail what we are talking about. I'm very interested in any systems that will reduce the risk factor inherent in solo wilderness climbing.

Cam, I have tried the figure eight descender also and I changed over to the rack quickly because of the twist factor that you are talking about.

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18 years 4 months ago - 18 years 4 months ago #123307 by jimk123
Replied by jimk123 on topic First Attempt at posting a diagram

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18 years 4 months ago - 18 years 4 months ago #123308 by Tom Dunlap
http://storrick.cnchost.com/VerticalDevicesPage/Misc/RappelSafetyPost.html

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18 years 4 months ago - 18 years 4 months ago #123313 by Tom Dunlap
Too often people think that a rap backup will work all of the time. It really isn't a 100% redundant system. Cloee though, it its designed properly. The most critical issue is making sure that neither part interferes with each other. In that case, the whole works collapses.

I think that adding a tool to take some of the load on a long rap is a good idea. When I climb with a hitch and I want to do a fast, long rap, I use an HMS biner attached to my hip d-ring below my hitch. The Munter is my primary and the cllimbing hitch is the backup. Me left hand is above the hitch and the right hand controls the MUnter. Since the left has to grab and the right has to slip, if my brain ever got inot overload one or the other will work since they are opposing. The normal response to panic is to grab tighter. I hope that this setup would work until my brain gets control of the situation.

In a rescue situation I don't think that your setup is the best. It takes too many hands to operate. Another issue is the lack of testing with two person loads. When I teach AR I prefer to not see the rescue load come onto one system. My preference is to have two parallel systems with a connection between the two.

Good discussion!

Tom

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18 years 4 months ago - 18 years 4 months ago #123314 by jimk123
Replied by jimk123 on topic Just to Summarize the Discussion
The purpose of this entry is to summarize the discussion at this point. The operative word throughout our exchange has been controlled descent. The underlying question is what method of descent and what application of technique establishes the greatest margin of safety? In relation to the DRT set with a Blake’s Hitch, the experienced climbers are using a descending device beneath this friction knot for the purpose of reducing friction. A consequence is a smoother descent. The worse thing that can happen to the Blake’s Hitch is over-heating of the knot due to the friction build-up during a fast descent. The result is rope damage. Though there are documented reports of Prusiks disintegrating on uncontrolled rappels, this is less likely to happen with the Blake’s Hitch for three reasons: 1) the resistance of the rope passing through the tree crotch diminishes speed. 2) these are polyester ropes with a higher melting point. 3) The Blake’s Hitch uses a larger diameter rope. The documented Prusik failures were on static rope systems where speed builds more quickly, and the failed ropes were made of nylon with a smaller diameter.

In “The Tree Climber’s Companion” beginning with page 64, Jepson is very disciplined to never mention the word rappel when describing the process of descending from a tree. Every description emphasizes controlled descent. Even the figure-8 is described as a descending device, not a rappel device. This wise choice of wording creates distance from the use of a tree descent as an adventure sport.

Thus, the concern of the tree climber continues to be how to make a descent absolutely safe. Though the Blake’s Hitch has a proven reliability for descent, climbers are working to reduce friction on the knot by establishing a back-up to it. The benefit is ease of control and reduced rope damage. Finally, personal judgment in a descent has the ultimate control on the outcome of events.

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18 years 4 months ago - 18 years 4 months ago #123315 by jimk123
The purpose of this entry is to highlight the discussions on the development of a “spider” configuration for descent in a DRT system using a Blake’s Hitch. Because the “spider” configuration places the descending device above the back-up knot, these are the aspects to consider: 1) it’s not a standardized practice 2) most descending devices require slack for installation 3) a descending device can be drawn into the lower knot if not protected 4) the descending device is placed higher from the harness.

The experienced climbers are achieving the benefits of reduced knot friction by attaching a descending device beneath the Blake’s Hitch. They’re using the traditional descent configuration: the back-up knot is above the descending device. The traditional configuration uses two hands to control the descent. One hand is working to release the upper knot. The other hand is controlling rope into the descending device (see Jepson page 65 for a diagram). When control of this traditional descending device is released, all the weight of the climber is transferred solely to the Blake’s Hitch –as designed.

In the “spider” configuration, only one hand is needed to control the descent. That control hand is on the Blake’s Hitch underneath the descending device, and it requires very little effort to slide the knot down. When hands are off the “spider” descent system, the climber’s weight remains largely on the descending device with only a small fraction of the weight returning to the Blake’s Hitch. Hence, less force on moving the knot down is needed. Otherwise, the mechanics of descending on the Blake’s Hitch are the same.

How is the descending device controlled in the “spider” configuration? The “spider” configuration operates on the same principle as the Fireman’s Belay or ground belay. In “The Tree Climber’s Companion” on page 64, Jepson describes a ground belay as a ground person pulling down on the rope. The tension in the rope stops the climber’s descending device. In the “spider” configuration, the Blake’s Knot is literally a hand pulling down on the rope. Like the ground belay, the Blake’s Knot creates enough tension to arrest the descent.

Much thanks to the feedback generated thus far on this topic. It brought forth discussions on techniques and preferences. Especially thanks to sawmill1 for being so thorough with his evaluation and establishing adaptations. As a reminder, a diagram of the “spider” configuration was posted a few entries ago. Remember to go “slow and low” until this is recognized as a standard practice.

Regards,
JimK

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18 years 3 months ago - 18 years 3 months ago #123481 by jimk123
The purpose of this entry is to provide the passage from Jepson 2nd Edition "Tree Climber's Companion" that echoes the voice of the experienced climbers on this topic of reducing hitch friction damage on a descent in a DRT.

p. 82

"Helpful Hint: Heat damage to the cord used to tie the friction hitch can be prevented during a descent on a dynamic climbing line system by first releasing and slightly loosening the hitch and using one of the following methods: 1) descend on a loosely formed foot lock on the climbing line: 2) descend on a Munter hitch tied to a pear-shaped locking carabiner attached to the saddle at a point below the friction hitch (a leg strap works well). Both methods are effective with any of the friction hitches used as a self belay."

Thanks for the sharing and productive input. The voice of the experienced climbers rang out clear on this topic.

Regards,
JimK

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18 years 3 months ago - 18 years 3 months ago #123483 by redpanda
"line: 2) descend on a Munter hitch tied to a pear-shaped locking carabiner attached to the saddle at a point below the friction hitch (a leg strap works well). Both methods are effective "


If you are using a flipflop 2tailed symmetrical lanyard (both ends of the rope used as separate Ddrt rigs), using a munter hitch will accumulate serious twistage in the system between your two ends.

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18 years 2 months ago - 18 years 2 months ago #123577 by jimk123
Replied by jimk123 on topic Time for a New Thread?
Sawmill1,

I've been using my figure-8 descending device positioned as a belay stitch plate in the Spider Rappel. The benefit is less twisting of the rope, which is commonly found with the standard figure-8 connection. In this altered configuration, a bight of rope is pulled through the figure-8 device. Then a carabiner is clipped through the bight. The carabiner is attached to the working side of the dDRT.

I'd like to propose that you start a new topic on this and post your pic above. Clearly I made this thread lengthy because I felt the need to clarify details on an unpublished application. I saw the need for caution.

Because it's the start of the climbing season, I believe your brief entry and photo would capture the interest of others to give it a try. More importantly, it would be good to gain their feedback.

Regards,
JimK

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18 years 2 months ago - 18 years 2 months ago #123578 by Tom Dunlap
Since I work off an SRT system my friction issues are doubled. I'm in the process of working on a hitch configuration that will work for SRT in the tree.

When I am ready to come out of the tree, I realized tonight, that I've been using the spider rap. I take my webbing sling and double it through the sliding d on my saddle. Then I clip in an ISC Mongoose biner. This puts the 'goose a few inches above my hitch fof the descent from the ground. The heat is in the biner not the hitch.

Tom

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