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Jay Wood
Trad climber
Fairfax, CA
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May 20, 2010 - 12:24pm PT
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EDK w/ 9.8, 7.8mm ropes after Royal Arches rappel.
Very slight wear where 7.8 comes out of knot
No knot rolling
Insignificant knot creeping down from rap rings
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HighTraverse
Trad climber
Bay Area
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May 20, 2010 - 11:39pm PT
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Always test your rap with full body weight before disconnecting your personal anchor.
An easy precaution to forget or ignore. But ignore at your own risk.
This isn't just about testing the anchor which you might be certain is bombproof.
It saves you from stepping back without your brake device secured to your harness. Which I almost did once. Would have certainly killed me.
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david.yount
climber
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May 21, 2010 - 09:22pm PT
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Autoblock and Autolock are similar, yes. But are they the same? No, they are not.
Petzl Grigri, Trango Cinch, these are autolocking belay (rap) devices. Through their cam design they progressively pinch the rope as the rope travels sufficiently fast through the device.
A friction hitch tied to rappel ropes below the primary rappel device is an autoblocking hitch. I commonly see this rigging referred to as an autobloc. I’m not sure if the exact hitch used in indicated, but most everyone chooses to use a hitch that would be a Hedden or a Klemheist if they took the terminal bight and thread it thru the beginning bight. I do believe the exact hitch is indicated, but I have not searched for citing or references. Klemheist, Bachman, Hedden, Prusik, Clove, Garda, Munter these are all Hitches.
Kong Gigi, Petzl Reverso 3, Black Diamond ATC Guide, these belay / rappel devices can be rigged in autoblocking mode for belaying climber(s) following a pitch.
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As rgold already shared, I remember a study I think was conducted by some from of national caving group interested in safety, they determined that a friction hitch was useless in preventing rappelling off the end of a rope(s). The volunteers, every one of them very experienced caver, only one person was successful, after several attempts, to let go of the friction hitch with their other hand when their braking hand felt the ends of the ropes go through.
Neither friction hitch rigging will help prevent rapping off the ends of the rope(s), whether fashioned above the primary rap device or fashioned below the primary rap device. But if your fancy is a hitch that is up rope of the primary rap device then consider the Klemheist Hitch. It has far superior sliding and braking characteristics than the Prusik Hitch.
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If you want to prevent rapping off the end(s) then tie a stopper knot at the end of the rope. Typically a double overhand is used in each rope. If you are rapping on a 7mm you might consider a larger knot profile than the double overhand. If using a 6mm line then you need to consider a larger profile stopper knot than the double overhand.
And, unless you saddlebag your line(s) every time you rap with knots in the end(s), then there is a risk of an end being whipped by wind, up and over, and the stopper knot jamming in a crack. And that crack may be nearly impossible to reach; you can’t climb up to it, you cannot ascend your ropes back to the rap station and then rap down and over to the jam because the traverse angle is too flat.
If using two ropes tie a stopper knot near the end of each line, separately. As you rappel, often twists will be introduced into each line. These twists will be ushered to the ends. If the ends are free to move then most of these twists will exit the lines. Never tie the two ropes together, you risk massive twisting and knots. This is not trivial; you do want to think about how to prevent your ropes from twisting and forming random knots upon each other.
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A carabiner brake rigged up rope from the primary rap device is far more comfortable then redirecting the brake lines thru a biner on the leg loop where now you need to raise the brake ropes to create more friction.
A carabiner brake has at minimum 3 biners. The attachment biner is recommended to be a locker. The frame biner is recommended to be a locker; and should really never be a wire gate non-locker. The brake bar biner may be most any style, but if it’s a large HMS shape it might not ride with stability. Or if it's a smaller biner than the frame biner then it may be more than challenging to rig it.
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When rapping on two ropes using a Munter Hitch I run both ropes through a single large knot. I’ve tried using a separate biner for each line. I found the single biner and single knot worked better. Though, the details escape me. If using 2 biners they both must be on your harness (or belay loop). You can’t place 1 biner on a sling because unless you have arms 4-feet long you won’t be able to generate sufficient friction on that elevated biner because to rappel on a Munter Hitch you need to raise the brake line vertically above the biner.
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david.yount
climber
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May 21, 2010 - 09:24pm PT
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I wanted to share my somewhat extended personal experience with using a very large washer as a blocking device to keep the joining knot between a thick rope and a very thin rope from jamming into rap rings, it also prevents pulling the joining knot through rap rings. But, I advise do not use a washer for this purpose.
Some words within this thread (not direct quotes):
The washer is simply a way to enlarge the effective outer diameter of the knot, so that it will not pass through the ring.
If I was rappelling all the way down the Nose from the top, and I knew rings were in place, I might take a (2" outer diameter) washer. It does have the advantage of preventing any part of a knot from going through the ring, and it can't be "untied".
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My story:
I wanted the blocker washer system to work. It seemed ingenious and simple. I used it on many outings one year, involving dozens of rappels. I tried very thin metal washers (hard to find washers that are thin but also that large diameter), I tried washers with sufficiently small inner diameters that somewhat gripped the thick rope they were threaded on. I carried and experimented with several washers.
When you pull the rope, there is a chance the washer will slide off the end of the rope, in one of several ways. It served its purpose, you were kept safe while rappelling. But now you may be faced with additional rappels but you have lost your washer. The only solution is to carry as many washers as there are expected rappels.This is not a light solution; these washers have a lot of heft to them.
The most common way I have personally experienced washers sliding off the end of the thick rappel rope is when the washer sticks or jams against something as I’m pulling the thin line. The washer can get stuck or jammed quite lightly, but just enough that it sits still while I am pulling on the thin line and the thick line is pulling thru the fixed washer. If I am aware of this then I give a hearty flick to the pull rope to attempt to unstick the washer. But sometimes I cannot know the washer is fixed, it’s out of sight. It’s stuck, I don’t know that, I keep pulling the thin rope. The thick rope pulls thru. When the washer is fixed, rarely will it remain fixed, rarely will it remain on the mountain, rarely will it be lost with me never seeing it again. This happened to me once. One time the washer evidently got stuck and the thick rope pulled thru. I got the thick rope pulled down, but the washer was missing, it never came down. The other times the washer got stuck it also became unstuck. Sometimes it became unstuck for no reasonable ascertainable by me. Sometimes it became unstuck when the thick rope was free falling from it’s own weight. However the washer became unstuck I’ll tell you that it’s position on the thick line was close enough to the free end of the falling thick rope that often the washer that was stuck and then became unstuck is now dangerously close to sliding off the end of the thick rope. If my testing of this blocking washer system had occurred on vertical rock with no ledges I’m sure that the washer, when it became stuck and then unstuck, would have more often that not, ultimately slid off the end of the thick rope. The less than vertical rock and ledgey nature of the alpine routes I was climbing prevented the free end of the thick line from hanging vertically in space. If the thick line had hung down a vertical rock face after pulling, then the washer could easily slide down the vertical thick line, and the washer would slide off the end and the washer would free fall to the ground. By the way, that could make a dangerous projectile.
Well, I came to a direct and simple solution to the washer sliding off the rope. I would tie an overhand knot in the rap rope. Here was my updated system, beginning at the end of the rap rope. The end of the rap rope is tied to the pull line. Then there is a big washer. This washer prevents the joining knot from jamming into the rap rings, it prevents the joining knot from going thru the rap rings. Then there is an overhand knot. This knot secures the washer on the rap rope. Now there’s no way the washer will come off the rap rope.
Two problems sprung up. First was that overhand could partially jam in the rap rings. If the rap rings were sufficiently small (Metolius and another type I forget) andn the rap rope was sufficiently thick, then the overhand would partially jam in the rings. This jam would make it difficult to pull out when yanking on the thin line. But the real problem was far worse.
Further, the washer can jam or stick in suck as way to prevent the thick rap rope from being pulled further. The presence of the washer can jam your rap rope. When I never yet used this system, but just thought about it, I didn’t think the washer could be the cause of a jammed rope. I thought, hey, the washer is metal and metal slides across rock so easily, and the washer is round, and round things roll they don’t get stuck. I never foresaw a reasonable risk that the washer could ultimately jam my rope.
The washer can jam in a constricting crack the same way a round rock jams in a constricting crack. And the washer can jam in a vertical orientation which causes sufficient retention / friction on the rope that the rope cannot be pulled through the fixed washer. And if you use an overhand knot to captures the washer so that it can’t slide off the end of the rap rope, then this very same overhand will be the knot that fixes your rope when the washer changes basic nature from a safety device to a piece of pro in a crack.
I guess I’ll leave the washers on my bench in my garage, they’re not for rock climbing.
That being said, when I rappel using a thicker rope (like a 10mm single rope) and a much thinner rope (like a twin rope) or a thin pull line (7mm or 6mm accessory cord) I don’t enjoy using the heavily canyoneering tested rigging of a carabiner block (best to tie the clove hitch on the spine of the carabiner). I do use the carabiner block while canyoneering; it’s a standard for single line rappelling, and all of the anchors are equipped with Rapide Screw Links / Quick Links. Though, in the recent 3 years I’ve gotten into “ghosting” newer canyons so no webbing and Quick Links are left behind; nothing is left behind of our rappels in these canyons.
When I rappel on different sized lines I join them with a flat overhand. I then take the tail of the thinner line and tie an overhand around the thicker line. I squish this right up against the primary knot. I believe there were some tests, though likely not nearly enough, on this exact rigging? I always put the thick line through the anchors. I rap on both lines using a tuber device, like an Omega Pacific SBG-II. And then I rig a carabiner brake on the thin line. This carabiner brake is rigged up rope from my primary rap device.
I’ve used this exact system on 10mm main rope and using any one of 3 thinner lines: 6mm cord, 7mm cord or 7.4mm twin climbing rope. I’ve logged over 50 full length rappels on this system and never had any rope creepage. The extra friction offered by the carabiner brake on the thin line allowed me to rappel comfortably, I did not need to apply extra hand gripping force to the thinner line. The thin line did not creep upward. The joining knot did not creep into the rap rings.
But I gave up on 6mm pull lines. Always tangling itself, tangling in the main line, tangling on bushes, tangling on rock features, and wind causes havoc. As well, they wear out fast! First I got 65 meters of 6mm, and eventually the sheath looked hashed. So I bought another 6mm 65 meters long. When that sheath / cord wore out I switched to 7mm. Oh! Pulling was much less crappy with a 7mm compared with a 6mm. And my buddy’s 5mm I only agreed to use once, one day of rapping with his 5mm line and I told him I would never use that 5mm again; pulling is ridiculously stretchy and painful on the hands. But the 7mm still was not enjoyable. It tangled in all the same ways and was horrible in the wind. So I moved up to one of my 7.4mm Twin ropes. Behavior was better and I could use it to climb on by doubling it up.
Ultimately, I got a pair of Half Ropes 8.4mm in 1998 and that’s all I climb on. It’s been 12 years of no fooling around. Two ropes for increased safety in falls over sharp edges. Two ropes to easily mitigate rope drag on wandering alpine and crag routes. Two ropes to increase safety for the follower on traversing sections that are followed by a vertical section. Two ropes for full length rappels. Two ropes for increased safety in case rockfall cuts one rope.
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Clint Cummins
Trad climber
SF Bay area, CA
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May 23, 2010 - 11:25pm PT
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Thanks, Jay - it looks good.
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janeclimber
Ice climber
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May 25, 2010 - 02:08pm PT
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Hey, David,
Could you please elaborate on the carabiner brake you mentioned in your earlier post? It would be super nice if you can post a photo of your set up. Thanks!-Jane
"When I rappel on different sized lines I join them with a flat overhand. I then take the tail of the thinner line and tie an overhand around the thicker line. I squish this right up against the primary knot. I believe there were some tests, though likely not nearly enough, on this exact rigging? I always put the thick line through the anchors. I rap on both lines using a tuber device, like an Omega Pacific SBG-II. And then I rig a carabiner brake on the thin line. This carabiner brake is rigged up rope from my primary rap device."
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david.yount
climber
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May 26, 2010 - 04:57am PT
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Jane, both the thin line and the thick line are rigged into my rappel device. Ask if this is not clear. My right hand is my brake hand, it holds both ropes and controls my rate of descent. I also clip a 2-foot sling to my belay / rappel loop on my harness. I clip a carabiner brake to this sling. The carabiner brake is rigged onto the thin line. The carabiner brake rides on the thin rope about 1-foot vertically above my rappel device.
The carabiner brake creates a mild amount of friction on the thin rope. In my experience I have found that this additional friction on the thin rope prevents the thin rope from slipping through the rappel device faster than the thick rope. The carabiner brake prevents the thin rope from creeping relative to the thick rope. My brake hand holds on to the 2 ropes normally and adjusts rate of descent normally. I don't pay special attention to grabbing the thin rope with greater force than the thick rope.
I hope this helps; I'm not the type to create demonstrations, take photos, and then post the photos.
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clifff
Mountain climber
golden, rollin hills of California
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Here's a super way to tie an EDK - the Double Overhand Knot _ check crasic's post:
http://www.supertopo.com/climbers-forum/1904819/Rappelling-knot-for-different-diameter-ropes
It's about a million times better than the simple overhand knot of the traditional EDK. If you examine it carefully you can see that it can be tied 2 different ways. The same topology but the working ends are switched. I don't know which is best.
photo - crasic
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