14. Snow Anchors – Equalization
In this video we look at how to equalize snow anchors.
Building snow anchors follows many of the same principles as building rock anchors. The force placed on snow anchors tends to be less than on rock. The exception to this would be haul systems for crevasse rescue.
When building anchors there are many acronyms used as a checklist to make sure your anchor is relatively safe and acceptable.
SRENEA is one acronym:
S stands for Solid – meaning the individual components are solid and well placed. For snow this means that you have good snow and your picket or T trench points in the correct pull direction.
R stands for Redundant – snow anchors are different from rock anchors in this regard. It may be necessary to back up (and make redundant) an anchor that will be used for crevasse rescue, or for climbing steep pitches of snow. However, since snow anchors are time consuming to build and the forces involved in a fall often less than on rock, we sometimes accept a non-redundant, single point anchor.
E stands for Equalized – meaning if I apply a force to the master point, then force is evenly distributed among the individual components. It is important to note that equalization must be FIXED in snow anchors because if the equalization shifts, as in a sliding X, the pull will be out of alignment with the T shape of the picket (or V shape, in the case of a midclip picket), and the anchor will slice through the snow. The primary way snow anchors fail is in shear. Shear is where a sharp object slices through the snow. The second way they fail is in compression.
NE stands for No Extensions – this means that, if one component fails, it will not shock load the remaining pieces in the larger system.
A stands for Angle – We want to keep the vector angle as low as possible. For snow and ice anchors, we are able to minimize this angle by placing our anchors in series, if we need multiple snow pickets or T trenches to create a confidence-inspiring snow anchor.
For snow anchors, one or two pieces may be adequate. For ice anchors where there may be solar melt-out, there are times where 3-4 screws are advisable—especially if people will be using the anchors for a top rope which tends to put the greatest force on the anchors due to cyclical loading.
Many of these anchor concepts can be reviewed in our videos on “Building Traditional Anchors”.
However, please watch our videos on individual snow anchors for a deeper understanding of alpine techniques.
We hope you found this video helpful. Feel free to comment below with questions or thoughts!
Please remember, climbing is inherently dangerous. Climb at your own risk.