Redundancy. It’s the “R” in every climbing anchor acronym from SERENE to ERNEST. Everyone who builds climbing anchors is at least familiar with the concept. But I often see confusion among new climbers, and it breaks down into two questions: Why do we make some things redundant while ignoring others? And how much redundancy is enough?
What is redundancy?
Let’s start with a brief introduction to the idea of redundancy in climbing anchors. John Long and Bob Gaines summed it up well in their classic book Climbing Anchors: “Redundancy demands that anchor systems be constructed of multiple components—from the primary placements, to the slings and carabiners we use in rigging the placements together—so that if any one component fails, the anchor will not fail.” The key point is that every point of the anchor system should be redundant—from the primary placements all the way to the master point—so that if any part of the anchor fails, either by breaking, coming undone, losing attachment to the anchor point, etc., the anchor itself will still work.
Check out: Best climbing packs 2021
How important is redundancy in a climbing anchor?
Climbing Anchors cites a NASA study to show the rate of failure in a given system and how redundancy affect it:
“It’s instructional to understand what NASA discovered in a study of redundant systems:
- Assume that one leg of your anchor has a failure potential of one in a thousand
- It follows that two equal legs would have a failure rate of one in a million (1,000 x 1,000)
- Three legs would slightly increase the reliability
- Four and up make practically no difference”
Since most of us plan on doing at least a thousand climbs in our lives, it’s  much better to have a climbing anchor with a potential failure rate of 1 in 1,000,000  than 1 in 1000.
RELATED: The Different Types of Climbing Explained
Why don’t we make ropes and harnesses redundant?
A common question many people have about redundancy is “If redundancy is so important, why don’t climbers use two ropes or two harnesses?” There are two basic answers. First, this equipment has innate redundancy built into it. Climbing rope is made of multiple strands of twisted rope wrapped in a sheath and a harness has multiple tie-in points, making it redundant. Second, ropes and climbing harnesses are reliable in a way that anchors aren’t, since they’re made in a controlled environment to specific standards. On the other hand, a “system” (e.g. an anchor) is inherently less reliable, since it’s created in an unpredictable environment where decisions are often made with incomplete data. As Curt Shannon says in Climbing Anchors:
“Boeing 747 aircraft do not have two left wings in spite of the fact that if a single, non-redundant left wing comes off, everyone on board will die. Same thing with use of a single rope. The point being that it is possible to design an element of a mechanism (such as a wing, or a rope) to a standard of quality where a lack of redundancy is a moot issue.” (emphasis mine)
The issue with climbing anchors is that we can’t guarantee the “standard of quality” of our primary placements or a stable environment. When we use things like cams, trees, bolts, boulders, etc. there are some good and reliable ways of telling if these things are safe, but we’re still making assumptions and educated guesses. And this is where redundancy saves us. Climbing Anchors again:
“Climbing anchors…are routinely fashioned in junk rock by people who little understand the gear or rigging techniques and have no experience in judging critical issues like direction of loading and fall factors. To help compensate for these variables, we foster a mindset and tender a criteria (redundancy) suggesting that you double up whatever you can, whenever you can.”
Read More: “How to Choose a Climbing Rope.”
2 common ways people unknowingly fail at redundancy
Fostering a mindset that encourages redundancy is critically important. Yet it’s still easy to get redundancy wrong. Let’s look at the two main ways people fail to properly apply the redundancy principle: 1. expecting redundancy to make up for bad primary placements, and 2. falsely assuming redundancy.
1. Bad Primary Placements
Redundancy can’t make up for a lack of strong primary placements. For example, you would feel good about making a climbing anchor of three bolts and equalizing the direction of pull. But the security redundancy usually provides becomes shaky when the primary placements are poor, for example if the bolts were rusty. Recall the NASA study mentioned before—the power is in having two or more placements that each have a very small chance of failure (like 1 in 1000). If your placements are poor, the odds of failure could go down to 1 in 100 or even 1 in 10, so redundancy doesn’t improve your odds that much. Even having more than one primary placement is problematic: perfect equalization is impossible, so one placement will inevitably be holding more weight, making it more failure-prone. And if that placement fails, the other placements can experience “shock loading”, putting immense pressure on the remaining placements and making them more prone to fail as well.
Want more climbing content? Check out our Climbing page
2. Falsely Assuming Redundancy
The second common mistake is assuming multiple carabiners, knots, or placements automatically means redundancy.  If you don’t fully understand systematic redundancy what you end up with is a partly redundant anchor that still has a weak point that isn’t redundant. Let’s look at 3 real-life examples.
Learn More: 15 Best Climbing Podcasts
Example 1:
I saw this anchor recently at a popular route atop Goat Rock in Castle Rock State Park:
This climbing anchor consists of one cordelette (neon green) tied around a large horn, then two locking carabiners, a sling with an overhand knot, then another sling girth hitched to the first sling. Then the blue sling ends at a master point with three non-lockers:
The redundancy issues are immediately clear. Â Starting from the top of the anchor:
- A single cordelette off of a single anchor point (the large rock horn) is completely non-redundant.
- Neither pieces of webbing below are redundant.
- In the red webbing, there’s a useless overhand knot that might have been an attempt at redundancy, but it provides no redundancy.
- Ignoring the girth-hitched webbing on webbing (why not use one of the lockers?), the master point isn’t redundant.
So while it seems like the builder of this climbing anchor may have been familiar with some redundancy concepts, they weren’t applied in a systematic way that made the entire anchor redundant. Any one leg failing would cause complete anchor failure. The only truly redundant parts—the carabiners—are also the least likely to fail!
Check out: 26 Best Climbing Instagram Accounts Everyone Should Follow
Example 2:
This one was sent by my brother, who saw it outside Asheville, NC. The climbing anchor consists of two slings, doubled over with a carabiner between them. I’m guessing the person felt that doubling the slings over somehow either made them stronger or redundant, though it does neither. But they could have actually created redundancy either by separating the slings and tieing them full-length side-by-side, or leaving the slings doubled over and tying a knot in both of them!
Example 3:
The entire climbing anchor is above. Again, the only redundant part of the entire anchor is the locking carabiners. Other than that it is one tree and one piece of webbing. At the very least the climber could have wrapped the webbing around the tree only twice, pulled both strands and tied a knot. This would have made the webbing redundant and the anchor much safer.
Conclusion
The goal of any climbing anchor is security. Redundancy is a critical component of any secure anchor system because it provides a margin of error that protects us against unpredictable environments in which we climb. Climbers should make sure they thoroughly understand redundancy and apply it to every anchor system they build.
If you enjoyed this article, make sure to check out our other How-To Guides, or you might also like:
