Un­der­stand­ing re­dun­dancy ver­sus equal­iza­tion.

Climbing - - CONTENTS - BY BRUCE HILDENBRAND

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.

BOLTED AN­CHORS

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.

TRAD AN­CHORS

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.

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