QC Lab: Autoblock Misuse

Lately I’ve been getting quite a few questions on the use of the Black Diamond ATC-Guide and/or similar “autoblock”-style belay devices—and another installment of QC with KP was born. I’ve seen some curious/scary autoblock uses/misuses out there and I had the boys in the QA lab test a couple of the setups I’ve seen, which were:

a) Incorrectly using a standard belay device as an autoblock device.
b) Using multiple biners as the “brake bar” in order to make taking in rope easier.

1. INCORRECTLY USING A STANDARD BELAY DEVICE AS AN AUTOBLOCK DEVICE

An autoblock-type belay device is awesome for belaying up one or two people on a multi-pitch route. When used correctly (utilizing a SOLID anchor, threaded correctly, always having your brake hand on the rope, etc) it is easy to take in rope and lock one or both strands should the seconding climber(s) happen to fall. However, I think the recent popularity in these devices has caused some confusion. A few weeks ago I was at Red Rocks on a super classic (read: crowded) route belaying my partner as he led upward. A climber below us joined me at the belay ledge and set up his belay system by equalizing the two-bolt anchor with a cordelette (the tie-in point was at chest height) and used a standard ATC device as an autoblock. I politely suggested that the belay setup wasn’t ideal as the belayer would need to raise their arm up above their chest (see photo) in order to lock off the climber, and they may not be able to hold the fall. The climber assured me that they “do this all the time” and that the seconding climber wouldn’t fall anyway because the climbing was “so easy.”


Incorrectly setting up a standard belay device off the anchor

Now whether this was a case of not understanding exactly how an autoblock device works, I’m not sure. I hope that it’s obvious to most people reading this that when using a standard belay device as described above it DOES NOT LOCK automatically if a second falls, and is VERY DIFFICULT to hold the climber by hand if he/she were to weight the rope. When using a standard belay device to bring up a second, I always belay off my harness’ belay loop, with the rope running through the anchor as a directional—that way if the seconding climber were to fall, the load is on the anchor. Some people belay off the harness straight down to the climber, but in the case of a fall, the belayer is now being yanked off the ledge and being pulled in two directions (the belayer is tied off to the anchor, but the pull from the fallen climber is downwards).

The correct setup of an autoblock device is shown below.


Correctly using an autoblock device off the anchor

The full instructions for the Black Diamond ATC-Guide can be read in  here in a PDF or watch the How-To Video on the ATC-Guide page for more information.

2. USING MULITPLE BINERS AS THE “BRAKE BAR” IN ORDER TO MAKE TAKING IN ROPE EASIER

I’ve had a few people write me claiming that, while using an autoblock device such as the ATC-Guide, they get pumped taking in rope when belaying their seconding climber up. It’s true that pulling up fat ropes (i.e. 10.5 mm and greater) has increased friction and therefore requires more effort than pulling up skinny cords. So other than not using such a fat rope, what are the options to make life a little easier? Well, I’ve had several people claim that they use multiple carabiners as the brake bar to help save the pump, but they’re worried about the potential loss of locking ability should their seconding climber fall. So I asked one of the members of the crack-crew of QA engineers here at Black Diamond to run a few quick, unofficial tests using two of our most popular models of locking carabiners, the RockLock (rounder cross section) and the VaporLock (flatter cross section). Here are the results:

Take-Up Force

Take-Up Force

In the testing we did, using multiple (two) biners actually INCREASES the amount of force required to take rope in.

• I believe this is because though the radius of the rope going over at the top of the device is larger, the radius at the bottom, where the rope pinches, is tighter. As well, I think multiple biners are assisting in forcing the rope harder into the grooves of the device, therefore causing more friction and thus more force required to take up rope.
• What the data also showed is something that is pretty intuitive and many have noticed and realized in the field: the shape of a biner’s cross section had an impact on the amount of take-up force required. (i.e. round cross section biner = easier to take rope in; flat cross section biner = harder to take rope in).

Holding Force

Holding Force

We found, once again in the limited testing we did, that using two biners actually INCREASES the amount of holding force.

• Once again, for the same reasoning, though the radius the rope takes at the top of the setup is larger and you would think reduces the amount of holding force, the multiple biners cause the radius at the bottom of the setup, where it clamps on itself in the device, to be tighter and therefore INCREASES the holding force.
• And once again, the data showed that flatter cross section biners had a greater holding force than rounder cross section biners.

What is the ultimate solution? You need to find a balance that works for the given situation. I’m usually climbing on anywhere from two 8.1s, to a single 9.1 mm, 9.7 mm or even a 10.2 mm. I typically use a VaporLock (flatter cross section) when using skinnier ropes, and a RockLock (rounder cross section) when using fatter ropes.

Again, this is pretty rough stuff; as always don’t take it as the Gospel. More in-depth testing would need to be performed to come to any concrete conclusions. I’m sure there’s a point where more biners would reduce the take-up force and reduce the clamping force. Is it three biners? (No, because we tested that…) Could it be four or five? Not sure, as we didn’t take it that far. And it goes without saying that I’m not a climbing guide and I don’t even play one on TV. If you want official instruction get it from a qualified, certified instructor.

Climb safe out there,

KP

Recent Talk (1)

• Jamie
  15 Jul 2009, 7:43PM

  Hi, sorry if I'm being dumb, I was shown how to set up a belay from the top a couple of weeks ago (i'm very new to this). The way I was shown was to set up my anchors coming in to me, and to belay the seconder of my harness. Are you saying that this isn't the best way to do it. I understand everything you mention about the dangers of autoblocking with the incorrect belay but I don't quite understand what you mean by using the rope as a directional in this sentence: "I always belay off my harness’ belay loop, with the rope running through the anchor as a directional". Would it be possible for you to clarify this to me? Thanks.

• Martin
  16 Jul 2009, 1:43PM

  He means that he's actually facing the anchor and the rope goes from his belay device (which is setup totally normally) through a piece on the anchor (the 'redirect piece') and then down to the climber. If the second falls you get pulled into the anchor instead of being pulled down by the climber and held in place by your attachment to the anchor.

• Kolin Powick
  16 Jul 2009, 4:02PM

  Jamie --
  
  Thanks for your question. I would recommend reading John Long's highly informative book "How to Rock Climb". On page 146, the book goes into excellent detail on this belay method and others. Be safe out there.
  
  -- KP

• Jamie
  18 Jul 2009, 8:44AM

  Hey thanks guys, I appreciate the answers, I'm pretty sure I understand what you mean, but I'll certainly try to track down that book as well. Sounds like it will be really useful. Thanks again.

• rj
  19 Jul 2009, 7:47AM

  COMMENT
  Kevin,
  
  I find your 2nd photo to explain how to set it up properly to be very confusing.
  
  http://www.blackdiamondequipment.com/uploads/black-diamond/images/autoblock2.jpg
  
  You describe a set up of connecting the device to your harness, but the photo does not show such a set up and at the resolution shown appears to be only subtly different than what not to do. Both appear visually to have the device somehow connected directly to the anchor point, even though your description makes it clear that your intention is to show a belay device connected to the belay loop of the harness with the rope running thru the anchor as a directional.
  
  I think it would be a service to BD customers if you replaced the "how to do it correctly" photo with one that better illustrates what you mean (e.g. put on a harness, clip in your belay loop, and show in a replacement photo what you really recommend for people to do).

• Rolf
  22 Jul 2009, 5:15AM

  COMMENT: thnx for this very informative post! But could you please put in higher res photo's? Especially the second one, displaying the correct belay, is hard to see (and figure out).
  Thnx.

• Rolf
  22 Jul 2009, 7:08AM

  COMMENT: Thank you for this very informative post! Could you however please display higher res photo's? Especially the one displaying the correct set up for use of an autoblock device is hard to figure out, and enlarging it blures the whole picture.
  Thnx,
  
  Rolf

• BD crew
  28 Jul 2009, 4:06PM

  Rolf --
  
  We have uploaded new higher res photos. There's also an excellent how-to video at http://www.blackdiamondequipment.com/en-us/journal/climb/video/howto-video-using-an-atc-guide that shows in detail the proper way to set up and belay with a ATC-Guide.

• Rolf
  31 Jul 2009, 1:08AM

  Thank you very much!

• Bryan
  29 Aug 2009, 11:49AM

  Three things:
  I have been testing and experimenting with what I think is a cool solution to lowering and then belaying a climber back up (i.e. Ouray Ice Park top managed belay) with an ATC Guide. I call it the autolock pass-through munter. There is a link to a drawing and image at: http://www.mscd.edu/~cra/oa/innovation/ropes.htm. It keeps the system closed during transition from lower to belay with no additional intervention. Would love your feedback.
  Second thing is - you all use "autoblock" while we have been using "auto lock" or "autolock". Is there a fine point of distinction between these terms or are they interchangeable?
  Great information above - thanks!

• Karsten Delap
  31 Aug 2009, 4:07PM

  I usually just use one extra locker to flip the auto locking device over into a redirected plate. I clip metal to metal with these lockers. The locker the rope runs through is never opened. This also gives me a carabiner of distance so that the redirect stays in the breaking plane.