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Tech Tip: Video "Occam releasable anchor"

Discussion in 'Tech Tips and Gear' started by Nic Barth, May 7, 2013.

  1. Nic Barth

    Nic Barth

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    I came across this a few weeks ago and was curious to hear some opinions.

    It is an anchor designed for a system where you are using bolt/ring or sling/link that will remain in the canyon. It says it was specifically designed for "descents with unknown rappel lengths." While most situations would work best with the traditional knot/biner block, I am intrigued by this system for drops with bad rub points or abrasion. This system is somewhat unique in that the descending rope does not need to be pulled through the anchor which means potentially less than half the amount of abrasion on the rope than with a traditional pull?

    Very easy to set up, use, and probably hard to screw up. I just tried it in the backyard about a dozen times- it worked effectively every time. It was a little finicky a couple of the times but I suspect a bit more rope weight would make it work smoother. I am keen to try it out in the real world anyway.

  2. Jimmy Olsson

    Jimmy Olsson

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    Wow, smart trick! Never seen that before. Interesting!
  3. Mike MacPhee

    Mike MacPhee

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    Cool idea, but I'm not sure anything is ideal for "descents with unknown rappel lengths." Beta (if available), a LONG rope, and several backup plans are probably the best armaments against such an instance.

    I really like the fiddlestick, as it releases both the pull cord and the rap line, so the total pull length is even less than the above system.

    As with all things, proper training, experience, and implementation are critical.
  4. Jimmy Olsson

    Jimmy Olsson

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    Mike: You seems to have experience of the Fiddlestick.

    Just a thought about the fiddlestick... Isn't it a little bit unstable? It can move/slide out if you get slack on the rope, right? So, isn't there a quite big risk that it might slide out of the rope if you for an example steps on a stone or something during rappelling and slack occurs?
  5. Mike MacPhee

    Mike MacPhee

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    As I said above, proper training is necessary to use this and any canyoneering tool safely. In general - no, the fiddlestick won't just fall out if the rappel line is unweighted. There is a danger that the pull cord could pull the fiddlestick out if appropriate force is applied. That said, the more weight applied to the anchor, the tighter the knot will cinch down on the fiddlestick, so this is very unlikely during rappel.

    Read through the link I posted above to Tom's Tech Tip for the Fiddlestick (also linked here), as it does a very good job of describing the usage of this tool. The best practice would be to back up the system with a carabiner for everyone but the last rappeller to minimize any risk associated with using the fiddlestick.
    ratagonia likes this.
  6. Jake Freimanis

    Jake Freimanis Ours is a quiet fear

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    Although I feel like toggling has effectively made the need for this style of anchor obsolete I thought I'd share 3 things we found from a bit of real world testing.

    First, I wouldn't agree with "probably hard to screw up" we had about a 1 in 10 failure rate and it took a while to figure out what was happening. There is a subtle difference with the direction and side the pullcord can be threaded through to make this work.

    Secondly, this anchor seems to be highly dependent on the geometry of the carabiner. We tried a number of different wiregate carabiners and few worked. The common BD neutrino wiregate was the only carabiner I had that worked. For this to work best both the spine and gate need to be relatively straight and not bent.

    Last, we tried this on a very sloped rappel and found that if there's enough friction to negate rope-weight one person may need to be pulling lightly on the rap side for this to work correctly. This then made it more difficult for the thin pullcord to lift the weight of everything. We had a 2mm dyneema line and we needed to use a munter on a carabiner to be able to pull hard enough on such a thin line.

    Again, this technique seems to be pretty much obsolete at the moment. Maybe it'll come in handy one day as more canyoneering systems develop so I figured I'd fling this information into the internet in case it's ever useful.
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