All anchors should be evaluated based on their adherence to the principles identified in the well-known SRENE acronym.
Solid: Each individual component should be sound and solid to the greatest possible extent.
Redundant: The U.S. Navy Seals have a saying: “Two is one, and one is none.” This old adage is particularly germane to building anchors. Make sure there is at least two (or more) of each component in the system.
Equalized: The load must be as equally distributed among the anchor points as possible.
No Extension: The possibility that failure of one of the anchors in the system will suddenly cause the overall anchor to extend, and thus shock load the remaining anchor points must be eradicated.
Basic top rope anchors are built using trees, chockstones, bolts, belay poles, or a combination thereof. When evaluating each anchor point, remember they must be as solid as possible.
Trees – Any tree used for building a top rope anchor should be alive, have a strong and sturdy root system, and be 6” or more in diameter. The general rule is: The bigger, the better.
Chockstones – Chockstones should be solid, free from structural cracks, immobile, and of great weight and size. If there is any chance that the chockstone could slide off the edge of the cliff or break apart, do not use it under any circumstances!
Bolts – Only use bolts that are 3/8” or larger (not the old ¼” buttonheads), that are solidly and fully driven into the rock, and free from rust. Also, check to make sure that the rock surrounding the anchor appears solid and secure. Evaluating the condition of bolts is a difficult thing to learn, but if the bolts and hangars look free of rust, solid, secure, and of the appropriate size, it is usually safe to use them, provided there is more than one bolt. If there is any question whatsoever as to the quality of the bolts or their hangars, DO NOT USE THEM. One of the benefits of top-roping is that you do not have to trust your life to any gear that appears anything less than 100% solid. If you are retreating off of an alpine multi-pitch climb in a storm, you may have to use whatever is available to you. This is never the case in setting up a top-rope. If there is any question, find another place to climb! It is also important to note that just because a crag is popular and you know many people who have climbed there, does not mean that the condition of the fixed protection (or bolts) doesn’t change over time. Weather, inappropriate use of bolts by other parties, natural decay of the rock, etc means that the quality of the bolts can and will change over time. Always use your best judgment and never hesitate to just say No! Notice that while the hardware on the bolt in Figure A is a little bit rusty, the bolt is newish, is fully driven, is 3/8” or larger, and has been driven into solid rock. This is likely worthy of use. The bolt in Figure B however is a rusted out, old ¼” buttonhead relic that will most likely grant the fool who uses it an express trip to the emergency room. Never use these old buttonheads under any circumstances whatsoever. It is better to free solo (climb sans ropes) than to weight a rope on these coffin nails.
Figure A
Figure B
Belay Poles – Belay poles, like bolts, must be solidly driven into the rock and in no way loose or movable. Make sure the rock surrounding the placement has not become cracked or broken, and that the belay pole is relatively free from rust or cracking.
Let’s take a closer look at the SRENE system.
Solid – You should ask yourself the following questions (and more) when determining how solid the individual anchor points are: Are the bolts in good condition, fully driven into solid and stable rock, free from obvious rusting and wear? Are the hangers tightly fastened or are they loose and spinning? Inspect each bolt carefully. Are the trees being used in a system alive, of sufficient thickness, and with a large and sturdy root system? Are belay poles fully driven and free from rust or other damange? Have the belay poles been fully driven into solid and stable rock? Are chockstones solid, immobile, and capable of withstanding large forces? Are all knots tied off correctly and the slings/webbing in good condition and free from abrasions and UV damage? Are all carabiners in good working condition with the gates tightly screwed shut? Inspect these factors very closely. After all, your life depends on it.
Redundant – Is there more than one bolt (or other anchor point)? Is the rope connected to the anchor with two locking carabiners with gates in opposition? Are you using two slings to rig your anchor? If you see some hot shot building an anchor with a single sling or carabiner, don’t think, ‘Wow, what I’m doing must be overkill.” Instead, say to yourself, ‘I hope he or she doesn’t get killed.’
Equalized – The anchor points should be as close to evenly sharing the load as possible. This is accomplished in a variety of ways depending on the situation, but it almost always come down to the angle at which the webbing or cordelette connects the rope to the anchor points, and the direction of the force being applied to the anchor (i.e. straight down or diagonal). Any angle larger than 60 degrees is likely to be dangerous. Aim for 45 degree angles or less. (See Figure A below.) If you need to decrease the degree at which the anchor is connected to the rope, then simply extend your webbing or cordelette. The longer the webbing extends from the anchor points, the smaller the resulting angle. If the direction of force can be predicted, then static equalization should be sufficient. This means that if the route follows a line of ascent that is directly below the anchor, then the anchor can be built without a self-equalizing or sliding knot. A common example would be three bolts connected with cordolette and a master point tied off in the predicted direction of force. If using bolts or belay poles, self equalized anchors can be built such that changes in direction of force do not change the amount of load being distributed to each anchor point. This particularly important component of the SRENE system will be explained in much greater detail later in this series as we confront various sample anchor building challenges.
Angle => Force on Each Anchor
0 degrees 50%
60 degrees 58%
90 degrees 71%
120 degrees 100%
150 degrees 193%
170 degrees 573%
No Extension – The possibility that failure of one of the anchors in the system will suddenly cause the overall anchor to extend, and thus shock load the remaining anchor points, must be eradicated. This can be accomplished in a variety of ways, including an extension limiting knot or through the use of static equalization as is the case when building anchors with the use of cordolette.
Discloures & Disclaimers: The author is not a certified climbing guide or instructor and the above post represents only what the author believes to be clear and accurate information. There is no warranty that this information is accurate or up to date, and the author and BayAreaClimbing.com assume no liability whatsoever in the event that climbers misinterpret or otherwise come to harm after reading the above information. Climbing is inherently dangerous. Climb at your own risk.
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