Jonathon asked, "have you ever used the 12-point system?"
"The 12-point system?" I asked. "What's that?"
Jonathon explained that it's a system used to evaluate student anchors. The goal is for the powerpoint in each anchor to have a value of twelve. The value is provided by individual pieces. A good cam or a good stopper is worth four-points. So if you have three good cams or good stoppers, you have a value of 12 at the powerpoint.
I have used the 12-point system to teach anchor construction ever since that original conversation. I find that students understand this complex topic far more effectively when it is laid out before them in this way. Following is a breakdown of the 12-point evaluative system:
- --A four-point piece is bomber. It should be able to hold a substantial fall.
- --A three-point piece is pretty good. It should be able to hold a short fall. An example might be taking a fall with your feet at the piece.
- --A two-point piece isn't very good. It will hold a fall with your waist at the piece.
- --A one-point piece is essentially aid gear. It will hold bodyweight, but is unlikely to hold a fall.
- --A large cam, 1" or more -- 4 points
- --A small cam, less than 1" -- 3 points
- --Micro cams -- 2 points
- --A large nut, a Stopper size 8 or greater -- 4 points
- --A medium nut, Stopper 4-7 -- 3 points
- --A small nut -- 1-2 points depending on size and rock quality
- --A very large tree with a good root base -- 12 points
- --A very large boulder that doesn't move and is on stable terrain -- 12 points
- --A good bolt -- 6 points
You should only build your body into a 12-point anchor if you need to do so for speed on a very big objective, or you cannot build a system that meets or exceeds 12-points. When you belay off your body it is difficult to escape the belay if anything went wrong...and if you're anchor is terrible, then a belay escape isn't really an option anyway.
There is only one magic bullet when it comes to building a good anchor, and that's experience. The concept of a 12-point anchor will provide you with a good foundation for anchor building, but to really feel confident, you're going to have to build a lot of anchors...
--Jason D. Martin