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Simpsonā€™s Pot - Anchors Rope wear

Ian P

Administrator
Staff member
Hi

On a recent trip through, I noticed rope wear on some of the existing anchors.
This week I had another trip through with Sam A to have a proper look. (No blood was spilt šŸ˜‚)

A number of anchors showed significant signs of wear, some of these are on short pitches (4m) although the ones on Slit Pot are possibly the most worn.

(It also became apparent that all 5 anchors on Slit Pot require replacement due to either been worn or loose)

We replaced a couple of the worn anchors and Sam has done a detailed analysis of them and produced his findings on a very nice technical document. (Attached)

The anchor team are in discussion to decide on a plan.

Thanks to Sam for his company, valuable experience and input, it is very much appreciated.

Ian

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Attachments

That's not bad for 32 years use. It's probably worth photographing (or measuring) the new anchors at regular intervals to compare wear rates (over years rather than weeks!)
 
That's not bad for 32 years use. It's probably worth photographing (or measuring) the new anchors at regular intervals to compare wear rates (over years rather than weeks!)

This was a potential ā€œsolutionā€, discussed, what would be really nice to know (but difficult to ascertain) is how long it has been popular as a pull through trip. I guess it wasnā€™t really popular 32 years ago, whereas now I guess (no evidence) it is the most popular method of descent nowadays.

Another factor I wondered about was if the modern trend towards thinner ropes has any significant effect?
 
Bolt Products make anchors in 6mm and 8mm stainless. The ones installed in UK caves are the 8mm variants. I would guess the DMM anchors are also 8mm steel. Given that the 6mm anchors are perfectly safe and strong enough, that suggests 2mm of wear should probably be fine... Certainly I personally wouldn't have concern about the integrity of the metal on those anchors (I would rate the risk of them pulling out as probably thousands of times more likely, which is probably still a lot less likely than the rock failing). I'm not sure what the thickness of the steel in an IC anchor is and whether it is equally resistant to wear, but I'd guess it's broadly similar.

Climbers know that top-roping through resin anchors absolutely destroys them in popular areas, hence why this is generally 'forbidden' (in as much as anything is forbidden in climbing). Fortunately, cavers are only pulling unloaded ropes through the anchors so much reduced wear (but then increased again by muddy gritty caving ropes, admittedly).
 
Seems an "open and shut case" to me?

Add a 10mm stainless maillion to each anchor and shove a big dollop of marine JB weld in the maillon barrel then krank it down tight with a pair of spanners (necessitates cutting it to remove, but prevents magpies making off with them).

Check them again in another 32 years šŸ˜‰
 
Pigs tails (as per picture) are very commonly installed on sport climbing routes on Portland specifically to reduce wear on the bolts. Very easy to use and obviously easily replaced. Ideal for pull throughs. Used as an alternative to chain & ring and (not that it's relevant to caving) can be used without untying and rethreading. Obviously requires 1 per bolt.
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I'd be interested to see exactly how the pull-through wear on the Slit Pot anchors compares to the wear on the anchors on the shorter pitches near Storm Pot. A longer pitch not only increases the length of rope to pull through, but presumably makes that rope heavier so it would wear the anchor more? Saying that, Slit Pot has two routes and a complete alternative route via Swinsto Great Aven, so perhaps the traffic there has been spread more over the years compared to the other pitches which might compensate for the additional wear of a longer pitch.

I can't think of many other northern pots where pull-through wear to the anchors might be noticable.
  • Heron Pot is just very short pitches.
  • Pool Sink probably isn't visited enough.
  • Walrus Pot at Top Sink, but nowhere near the same volume of traffic as Swinsto/Simpsons.
  • Calf Holes entrance, but do people pull through there given that it's usually novice trips?
  • Lost Johns', but probably not enough people have pulled-through.
So in that respect, Simpson/Swinsto are probably fairly unique in their volume of traffic and pull-through frequency.

I assume that hypothetically the IC anchor should wear at the same rate, as presumably it is the same grade of metal? Or is this an unknown and something we are only going to find out over the coming several years?

Either way, is this not a supporting arguement for the chain/ring system for the small number of longer pitches that are very frequently used for pull-through? As per the maillion/pigs tails options presented above, the ring can be replaced if becoming worn without needing to replace the anchors. Or is replacing the anchors every 30ish years something we are just happy to accept? The IC anchors can usually be extracted to allow the hole to be re-used (this was one of the conservation benefits of this anchor), but there's never absolute certainty.

Irrespective of the above, a massive thank you to Ian and Sam (who are also two of CNCC's most active anchor installers) for the efforts you are putting in to keep our anchors safe, and research potential issues such as this and come up with solutions.
 
I assume that hypothetically the IC anchor should wear at the same rate, as presumably it is the same grade of metal? Or is this an unknown and something we are only going to find out over the coming several years?
One factor Im not sure about is the effect of the different radius on the anchors.
DMM. 7mm radius
IC. 3mm radius

Probably something for someone who paid more attention at school than me šŸ¤¦
 
Smaller radius on the anchor means that the pressure of the rope is on a smaller area, so will wear faster, until the corner is rounded off to a bigger radius. A small radius also stresses the rope significantly; I would much prefer to pull through on a ring or maillon than directly through an IC anchor. A ring will suffer least wear as it can be rotated to spread the wear all round the circumference, the wear on a maillon is concentrated at the end.
 
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