Belaying directly off the anchor on slabby terrain

The user manual for the Petzl Reverso says not to use it in autolocking mode in a situation where the carabiner the rope runs around cannot move freely. This makes sense to me because the device needs to be able to rotate freely to ensure that the load strand clamps down on the brake strand, independent of the direction of loading. This seems extremely unlikely to actually cause failure under most circumstances, but it is not obvious to me that it is a negligible risk. If that advice is followed stringently, it seems there are many anchor configurations where belaying off the anchor is not appropriate for the reason that the carabiner the rope is running through will touch the rock. This never seems to come up in discussions of when to belay off the anchor...is there some reason I can't think of why this is definitely OK under some circumstances? Have there been accidents because of this?

I don't worry aboutit, but than again I normally just redirect off my harness, since it is easier to feed slack, and give tension, etc.

Yes there have been accidents when auto blocks failed to lock. It is not about the biner rotating as John mentioned above. But anything that could prevent the device from aligning with the direction of loading could prevent it from locking. Slabby terrain or not, anything that interferes with the free movement of the device could prevent it from locking.

If you have the slightest doubt, keep your hand on the brake side strand for the entire pitch.

Can't you just flip it over?

No. It's not just about the biner anyway. Anything that prevents it from free movement could be a problem.

I'm sure it doesn't make much difference either way. I love petzl diagrams in their catalogs. I think we could all agree that whether or not its safer, it's definitely cleaner and better for gear in the long run.

I use my ATC guide belaying off the anchors on slab all the time. I don't see any way that it could reorient in a way to drop a climber no matter how much swing the climber took. You essentially have to invert the whole rig for significant slack to pay out.

If this is unreasonably dangerous, I'd like to know.

how many times are you at an anchor on slabby terrain where the device is running right on the rock with the potential to not orient in the direction of fall?

On slab i'm usually clipped in and leaning back on my feet which pulls the master point out slightly from the rock, preventing this i guess. I have yet to encounter a scenario in which my autoasist device hasn't functioned properly due to the nature of how steep the rock is

how many times are you at an anchor on slabby terrain where the device is running right on the rock with the potential to not orient in the direction of fall?

On slab i'm usually clipped in and leaning back on my feet which pulls the master point out slightly from the rock, preventing this i guess. I have yet to encounter a scenario in which my autoasist device hasn't functioned properly due to the nature of how steep the rock is

Petzel needs to warn about this scenario although an actual failure is unlikely. They do warm about an even more likely scenario which I witnessed right in front of me. If the last piece of lead protection below the belay is off to one side, the anchor must be able to move freely in that direction. If it hangs up on something IT WIIL NOT LOCK.

Another scenario that they warm about is similar to the one I just mentioned but with two followers. If the first follower falls after passing the last piece of protection but has not reached the anchor yet and falls he will be pulling down on the device. Now. If the second follower falls, the device WIIL NOT be able to orient properly to lock his rope. He will zip to the ground. Not good.

Greg D wrote:Yes there have been accidents when auto blocks failed to lock. It is not about the biner rotating as John mentioned above. But anything that could prevent the device from aligning with the direction of loading could prevent it from locking. Slabby terrain or not, anything that interferes with the free movement of the device could prevent it from locking. If you have the slightest doubt, keep your hand on the brake side strand for the entire pitch.

can you give some accident citation/report links for the reverso/guide with the biner being blocked against the rock, not the ones where people tried to lower improperly?

i use autobloc alot on slab and have never had any issue ... even if the biner is touching the rock on slab, in a normal anchor setup it will move/rotate just fine as there no weight pressing down on it ... i can see where it might be an issue if it stuck against a rock feature, but thats easy enough to avoid when setting up the anchor

one thing to note is that the petzl method for ascending a rope with a gri gri shows the biner in a position that could easily be "blocked" ... of course they recommend you keep you hand on the rope

petzl catalog 2011

petzl.com/files/all/en/acti…

;)

bearbreeder wrote: can you give some accident citation/report links for the reverso/guide with the biner being blocked against the rock

No. As I said in my first post, I don't believe this would prevent the device from locking.

As far as the party of three scenario I mention above, I can't give you a link but I could give you a phone number. A friend of mine fell 40 feet when the device did not lock because it was not able to orient to the direction of pull because it was hung up on the slab. She was lucky. Only two badly sprained ankles. Could have been much worse.

Greg D wrote: No. As I said in my first post, I don't believe this would prevent the device from locking. As far as the party of three scenario I mention above, I can't give you a link but I could give you a phone number. A friend of mine fell 40 feet when the device did not lock because it was not able to orient to the direction of pull because it was hung up on the slab. She was lucky. Only two badly sprained ankles. Could have been much worse.

i can see the party of 3 happening ... petzl warns explicitly that the difference in the fall angle could cause the failure to lock of one of the strands

petzl reverso 4 instructions

the thing to remember with these devices is that they work by the climber strand pressing into the break strand, if they cant then down the climber goes !!!

for the smart anyways, simply pressing the biner upwards or downwards wont do anything ... which is why you cant give slack with a smart by pumping the biner like you do with a reverso/guide ... but what you DO need to watch out for is the handle getting caught on a feature

alpine smart thin version on 8mm phoenix

earlier this season i remember going some moderate 5.10 where my partner belayed me up with a gri gri .. the top of the climb at the anchors was slabby and my partner was belaying me direct ... the problem was that the grigri was oriented so that the cam was pressing into the rock ... its a good thing ive never fallen on that climb !!!

a polite word with my partner who didnt have as much experience belaying on multi, and he will never do it again ...

the problem i see over and over again is people using these devices ... guides. reversos, smarts, even normal ATCs and munters ... on multi not knowing their limitations, reading the instructions, or practicing problem situations ...

if i had a dollar for every time someone doesnt know how to tie off a munter/ATC, doesnt know how to lower off a guide/reverso, doesnt know how to even belay properly with a grigri ... id be rich

autoblock is an absolutely wonderful tool, especially in areas of rockfall ... but people have to know and practice how to use it and its limitations

;)

I avoid the whole issue by always belaying with a gri grioff my harness with a re-direct. Makes swinging leads a lot smoother, too.

Greg D wrote:No. It's not just about the biner anyway. Anything that prevents it from free movement could be a problem.

I meant flip over the belay device, not the biner. That way the biner that holds the rope in the device is away from the rock but the rope would be against the rock. As I recall the newest Reverso has the ring that it hangs from perpendicular to the plane formed by the rope entering and exiting the device (unlike the ATC-Guide where the ring is parallel to the ropes).

Bill Czajkowski wrote: I meant flip over the belay device, not the biner. That way the biner that holds the rope in the device is away from the rock but the rope would be against the rock).

I know what you meant. As I said before, it's not about the biner.