Understanding redundancy versus equalization.
UNDERSTAND THE PRINCIPLES BEHIND REDUNDANCY AND EQUALIZATION
When it comes to building belay anchors, many climbers confuse the terms redundancy and equalization. Redundancy means avoiding a single point of failure by having duplicate pieces of ( ideally) equal quality— if one piece fails, the other will take the load. Meanwhile, equalization means that the load is spread over multiple pieces of reliable or, often, potentially dubious quality. The two principles work together. Ideally, all anchors should be SERENE: Secure, Efficient, Redundant, and Equalized with No Extension—i.e., shockloading—if a piece pops. The key is understanding the quality of the pieces. Typically, after equalizing three bomber pieces, you’re ready to belay. We can waste time adding extra pieces that may be needed on the next lead by not realizing we have three solid, redundant pieces. Yet we put ourselves at risk if gear is suspect and un-equalized.
Two beefy bolts typically comprise sport anchors. When properly installed, bolts rarely fail. However, material defects or manufacturing errors can cause a bolt or hanger to break. In Yosemite in the 1970s, a batch of poorly manufactured Rawl split-shaft bolts started breaking, some even below body weight.
This is why redundancy matters. Having two bolts and accompanying hardware greatly reduces the risk that should one piece fail, the whole anchor will blow. Because each bolt, by itself, is theoretically strong enough, there is no immediate need to equalize forces. However, if one bolt breaks, having them equalized limits extension on the remaining bolt. This is why you see equalized lengths of chain or rings on anchors. These anchors present the best of both worlds: They’re both equalized and redundant.
When you have an anchor with one good and one bad bolt, since you lack redundancy, equalize the two with slings or a cordelette.
An anchor needs equalization when none of the anchor points can singlehandedly hold the forces generated. This is more common in traditional, multi-pitch climbing. If you can find bomber gear, then your primary concern, before you focus on equalization, should be redundancy. But if the gear (or bolts) is suspect, then spread the load.
There are many ways to minimize extension; the main concern is to reduce shockloading should one or more pieces fail. Most climbers use a cordelette: 15–20 feet of 7mm cord. With practice, you can master tying the cordelette ( see
sidebar) into the anchor points. You can also tie a quadalette ( see climbing.com/quad). And you can use slings, though it’s important to individually tension the slings to avoid extension.
How you construct the anchor can also help with equalization. If the rock is good, it’s best to keep the pieces close together in the vertical axis—for easier equalization, and reducing potential extension and significant changes to the angle of the load. Even if you have to spread the pieces out horizontally, placing them as close together (assuming reliable rock/placement quality) as possible will help with equalization and with minimizing extension.
BRUCE HILDENBRAND splits his time between the Bay Area, Boulder, and Europe. He is a prolific rebolter in both California and Colorado.