Saturday, 30 April 2011

GLACIERS & CREVASSES: PART ZWEI! (Solo retrievable loop-systems)

Whereas the first offering in "Blog-1" could be considered when making a crossing alone when time is limited, this second series of techniques could be useful when a crevasse is readily apparent and there is a very real danger of a fall that requires self-rescue. The Sack-drag in Blog 1 used no positive anchor system. The following techniques not only demonstrate anchors but also demonstrate the retrievability of all equipment once a solo crevasse crossing has been safely made.
I designed these systems many years ago so that they could be used either independently or in union with the Sack-drag system in Blog-1. As usual, all the equipment required is "alpine standard", though its use as depicted may be considered by some to be unorthodox.

Rope loop anchor system, using hip belt

As I have explained in many previous blogs, much of my overall soloing rope technique is based on "rope loop" systems. These are just simple variations on a retrievable protective system that I use on narrow, exposed ridgelines in poor conditions. Being essentially a very lazy solo climber, I try to develop very simple, multi-purpose rope work that requires as little thought and effort to execute and retrieve as possible.

Diagram of above system for wet glacier.

Even though I find wide hip-belts useful for this sort of thing, I can't stand the bloody things on any sack smaller than 60 litres. There just isn't any point. Big, bulky, restrictive, uncomfortable -- bring back the good old waist strap, I say!!
This system gives a good 25 - 30 metres (depending on rope length) to effect a crevasse crossing. The self-belay and arrester devices are a personal choice - I use either a reversed shunt on a dynamic rope sling, lark's-footed to my harness, or a dynamic sling "classic Prusik" around a doubled rope.

Feeding rope from rope-bag through the shunt. If at this point the climber should fall, the shunt will arrest the fall.

It is important to add that neither the shunt not the Prusik are made for shock-loading, but every system I devise is tested at our local climbing-wall at least 6 times at factor 2, and so far none have failed me.

Second option: Shunt is replaced by a Classic Prusik from a dynamic sling connected direct to harness.

Once the crossing has been safely made, the knot in the rope bag is undone and the rope is retrieved by a slow steady pull on the side connected to the sack. The inertia of the sack's weight easily dislodges and retrieves the entire anchor system. You then simply continue to steadily pull until the equipment arrives at your feet, and the remaining rope's end is pulled through the vacated anchor point.

It is critical that the retrieval be slow, firm and steady. Pulling quickly can cause the rope to "throw a knot", which can easily jam at the vacated anchor point.
One of the other options of an anchor uses multiple "Abalakovs" on hard, "dry glacier" ice. Note:The first option can also work on a hard ice bollard without a hip-belt addition.

The anchor system can only be as good as the compaction and quality of the ice it is constructed in. Make a thorough assessment, and test your anchors before trusting them to a fall.
I always liked the idea of a simple "ice core" drill on the end of an alpine axe instead of the usual spike. It's a very simple modification which would do both jobs and enable one to bore out good-diameter Abalakovs in hard dry-glacier ice. I suppose someone will think of it one day, and incorporate it into an axe-handle. Even the longest ice-screws are not really up to the task as Abalakov anchor-drills.

Good climbing,