I can understand alerting people to the issue. At the same time, shoe-horning in the word "shock load" for every fall appears disingenuous.

You're missing the point and clearly haven't read my responses.

You're missing the point and clearly haven't read my responses. We're talking about the anchor, not the climber.

I made the analogy to hiking down hill. Every one of us has experienced the shock loading on our knees from a long downhill trek. There's nothing ballistic about those gravity loads, but they're clearly more damaging than simply holding up our static weight - enough so that they can destroy knees over time.

Standing with locked knees is an alpine technique called Alpine lock-stepping or the Mountaineer's rest step - this allows the joints to recover from the shock-loading of down stepping by maintaining a static load for a moment.

If this is common sense language in hiking, it should be just as commonsensical in climbing.

If you look up SERENE anchors, you'll find these two websites:

The American Alpine Institute
http://alpineinstitute.blogspot.com/2008/05/popular-anchor-acronyms.html

"No Extention" means that if one piece fails, the anchor will not shockload other parts of the system."

Gaining Elevation: Climbing and Mountaineering Resources
http://www.gainingelevation.com/content/sereneernest-anchors

" No Extension - Anchors should be built so that if one or more of the components fail the remaining components won't be shock loaded."

Danger!!!!!! Triaxial loading!!!!!!!!1

I am putting together my first TR kit. In the past I have always done my anchors by slinging two bomber trees with webbing long enough to almost meet. Then I connect the two pieces of webbing with biners to a sling acting as a sliding x.

Would it be fine to use two slings instead of one? I was just thinking that everything in the system is backed up except for the sling. Having two slings put together would make the system more redundant, but would it create any unnecessary friction possibly messing with the sliding x?

Thanks!
Dave

Not if you tie two individual pieces of webbing into a joined knot before you clip the locking 'biners into them.

Good call on inserting the warning.

I want to make a Reel Rock contest video where the characters only speak in quotes taken directly from this website. This would be one of them.

I am putting together my first TR kit. In the past I have always done my anchors by slinging two bomber trees with webbing long enough to almost meet. Then I connect the two pieces of webbing with biners to a sling acting as a sliding x.

Would it be fine to use two slings instead of one? I was just thinking that everything in the system is backed up except for the sling. Having two slings put together would make the system more redundant, but would it create any unnecessary friction possibly messing with the sliding x?

Thanks!
Dave

That was actually a bit of a joking reference to this thread, where rescueman's concern over triaxial loading in TR anchors degenerated into ten pages of poop flinging.

Don't kid yourself. Unless you keep the belay tight to the climber at every moment, then any fall is a shock load.

Even a fall on a perfectly tight belay imparts double the climber's weight on the rope and about 1.67x that on the anchor.

I want to make a Reel Rock contest video where the characters only speak in quotes taken directly from this website. This would be one of them.

Even a fall on a perfectly tight belay imparts double the climber's weight on the rope and about 1.67x that on the anchor.

Never does the rope experience more than the weight of the climber in this situation! How could it since there is nothing heavier than 200 lbs hanging on it?

That's your assumption and is incorrect. Not a lot I can do about that.

As to those who decry the sliding X, I want to see a show of hands of those who have blown out a top rope anchor?

All the sensible responders here have stated that a sliding X is unnecessary and may be problematic.

The core of my initial response was:"Unless you're planning to use one anchor for multiple routes or climb far off-route, a fixed focused multi-point anchor is safer than a sliding X. Use the KISS principle and don't over complicate a simple top rope anchor."

But some bozos here cherry-picked my use of the term shock load and hijacked the thread rather than focusing on our points of agreement: Keep it simple and safe.

Here's the kind of unanticipated consequence that can occur with such a system with just a couple of foolish errors.


Fatal Climbing Accident
Happy Hour Crag, Boulder Canyon Happy Hour Crag, Boulder Canyon, April 20, 2000

The upper anchor system, set up for a “top-rope, bottom belay” on Dementia, failed while a climber was being lowered, resulting in the death of the climber. Both the climber (victim) and partner reportedly had years of active experience at 5thclass climbing.
• The anchor system was rigged by the climber using webbing purchased by the climber the day before—specifically for this climb. The knots in this webbing were tied by the climber at the anchor just prior to the climb.
• The climber had reportedly put his weight on the belay rope, and thus on the anchor, during the climb.
• The anchor system failed as the climber was being lowered. The climber fell 60 ft. and was fatally injured.

[image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=5946;[/image]

[image]http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=5947;[/image]

It's dumbfounding that people today demand "scientific proof" for a practice that common sense would require. But common sense is, perhaps, the least common sense today.

Part of the SERENE principle (that is generally accepted) for any kind of climbing anchor is "no extension". A self-equalizing anchor allows extension upon failure of a single leg, which results in dynamic loading and shifting of the remainder of the system.

And, by the way, some climbers routinely top rope on static line, and webbing is a good deal more static than static line, which has up to 6% stretch at 10% of MBS.

The trees might, in fact, be "bomber" and 4,000 MBS webbing is more than strong enough, but webbing abrades and cuts very easily at an edge and there have been fatalities when climbers have used brand new webbing with taped joints from the manufacturer's spool. Improperly tied knots can slip apart. In other words, shit happens.

If one leg of the anchor should (for any reason) fail, then a sliding X would allow both sudden extension and a re-orientation of the remaining leg over the rock edge, potentially causing rapid abrasion and cutting.

Others here have advocated the same general principle: KISS. Don't complicate what should be a simple anchor system. The more pieces of gear, the more connections and - particularly - the more potential for sudden extension and abrasion, the more potential for failure.

KISS: Keep It Simple & Safe.

I don't make assumptions ...

Uh huh.

But some bozos here cherry-picked my use of the term shock load and hijacked the thread ...

Seems you've done your share such as "half a fishermans" versus the terms you prefer.