Author Topic: Resin bonded anchors  (Read 1762 times)

Offline MarkS

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Re: Resin bonded anchors
« Reply #25 on: May 17, 2021, 09:10:03 am »
In some ways I didn't phrase my last post very well. Inevitably on the approach to a pitch there is a variation from no/minimal risk of injury if you fall, to almost certain death if you fall. Anchors obviously need to appear near the start of this, probably with the first vaguely near "minimal risk" and the second vaguely near "moderate risk", although these are extremely subjective.

In quite a few cases the risk is minimal to none until you are on the pitch itself, which was certainly the case in Marble Sink where we placed virtually no anchors before any pitch heads because it's all but impossible to fall down any of them until you are on them! I suspect the rationale for Quaking was much the same. With that in mind, I was surprised to see a comment above suggesting there should always be an anchor before a pitch head.

If anyone has concerns about any anchors (or lack of) on routes in northern England (some sensible suggestions above) then pass them on to the CNCC. If approved at a meeting, they will be added to the list and addressed when installers get round to them.

Offline Cantclimbtom

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Re: Resin bonded anchors
« Reply #26 on: May 17, 2021, 11:03:23 am »
...I buy a 200m reel of rope about every year to rotate the stock....
minor digression, I am seeing both 10.5mm and 11mm semi-static (Low Stretch Kernmantle) on 200m reels made by Southern Ropes (well respected manufacturer in South Africa, although almost unknown in UK, CE certified, Cert of conformity) that is designed for Industrial and Cave, usually about £175 a reel. Search ebay for  "LSK  10.5" for example. Hope that helps
Edit, bought a 60m offcut recently and happy with it.
Expert in incompetent tomfoolery

Offline mikem

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Re: Resin bonded anchors
« Reply #27 on: May 17, 2021, 12:13:28 pm »
Although spits were massively more prone to failure, they at least had the advantage that it was relatively easy to inspect their condition. Resin bolts will start to fail at some (probably far distant) time in the future & we also owe it to those cavers to come to provide protection against that.

In positions where the failure of a single rebelay would endanger the participant (swinging the rope into sharp edges, or them into walls or falling water mass), then two bolts would seem to be preferable (potentially by including a single intermediate rebelay, rather than Y hang - depending on options available & noting that, if the lower bolt fails, a short rebelay has a much greater shock load than a Y hang).

It's great having single hang big pitches, but in popular caves the option to break it into multiple rebelays allows the entire group to keep moving.

I'm quite happy to rig off the odd loose resin bolt, as long as it's not pulling in line with the placement, & it's not the quality of the rock that's the cause.

Natural anchors are great, but if the rope is loaded (especially if the caver has to swing around below them), then they may end up cutting into the rock, so metalwork may still be a better option - from a conservation point of view.
« Last Edit: May 17, 2021, 12:43:46 pm by mikem »

Offline Badlad

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Re: Resin bonded anchors
« Reply #28 on: May 17, 2021, 12:21:00 pm »
There are some very interesting points in this discussion although not necessarily answering the OP's questions (sorry Sam).  Clearly there are differing views with many specific points being subjective and dependent on circumstance. 

What I don't really get is how some would insist on two resin anchors even before there is a risk of a fall and yet everyone seems happy to rely on a single rope for the whole descent.  I am fairly sure that the likelihood of failure of the resin bonded anchors is much lower than the likelihood of failure of the rope - so why aren't people using two ropes and 100% redundancy in the whole system rather than just 100% redundancy in the bombproof anchors?

Offline mikem

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Re: Resin bonded anchors
« Reply #29 on: May 17, 2021, 12:41:07 pm »
Because the rope is something you have control over (how you look after it & how you rig), but the bolts aren't.

Pretty sure that modern rope failures are almost as rare as bolts (& quite often will be caused by issues with the bolts, or poor use of them). This does ignore the more common problems of clutch & plummet, or melting through the sheath on long abseils, but they are not really failures of the rope.

Long term, anchors are not 100%!

& when cavers tried double ropes more people got hung up, causing exhaustion & requiring rescue...
« Last Edit: May 17, 2021, 12:52:10 pm by mikem »

Offline Ian Ball

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Re: Resin bonded anchors
« Reply #30 on: May 17, 2021, 01:03:23 pm »
Quote So initial questions I ask myself in this order:

  1 Is there a suitable natural belay?
  2 Is there a suitable natural belay that can be improved with a hammer (normally knocking sharp edge off a flake or similar)?
  3 Can I drill a hole?
  4 If the above can’t be done placement of anchor/s should be as few and high as possible to enable a safe approach, descent and ascent of a pitch.
[/color]

a. Now can these principles be retrospectively applied to a cave that has resin bonded anchors already installed under the BCA scheme, or should something different be used?


YES, perhaps you could treat a sound resin anchor as a natural in the above order?  I would say that a sound natural slightly out of the best placement is better than an extra bolt and so a sound resin anchor slightly out of the best place is better than another one going in as well.  If it were to come lose in the future, it can be improved then.

B, C, D

Only if it removes an unacceptable risk when used as intended

e. Can/should anchors be placed to make it easier to pull through, there are already anchors that allow a safe approach for hard rigging but aren’t great for pulling through?

Yes, I think it is a good idea.  Also perhaps different technology such as those rings in Giants to both identify as pull through bolts?

f. If an anchor or series of anchors are loose can they be removed, assuming the original anchor placement wasn't damaged when removing them. Then place new anchors in better location i.e. higher up?

If we say a loose anchor is a bad anchor then they should be removed and the pitch approached as a new installation

g. If an anchor or series of anchors aren't loose can they be removed. Then place new anchors in better location i.e. higher up?

Only if it removes an unacceptable risk when used as intended.

h. I assume no one has issue with the removal and replacement in the same location of a loose resin bonded anchor?

correct

i. Can/should resin bonded anchors be added to existing traverse or route to make it easier more user friendly?

Yes, originally I was against this, but thinking about Rachels post about struggling to rig safely because bolts are too far apart means that they are not really doing what they are intended to do.

j. Is there a point at which resin bonded anchors should no longer be installed?

Where there is danger of damaging the rock for the other bolts perhaps?


Single v double anchors is for another page I think

Offline mikem

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Re: Resin bonded anchors
« Reply #31 on: May 17, 2021, 01:28:58 pm »
Maybe a better term of reference should be that, for long term rigging, there are two anchors before you are relying on the rope in a fall arrest situation (but again this point is different for different people).

Particularly those fixing CNCC bolts need to consider that what is an easy reach for a 6 footer, may require someone who is only 5ft tall to put themselves in a dangerous position, or can be impossible.

If nothing is changed in a cave then it is everyone's responsibility to look after themselves, if you are fixing bolts for others to follow, then you have a duty of care towards future cavers (& then there's a whole spectrum of possibilities in between those positions).
« Last Edit: May 17, 2021, 01:46:04 pm by mikem »

Offline Ian P

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Re: Resin bonded anchors
« Reply #32 on: May 17, 2021, 02:13:45 pm »
As a bit of background and hopefully to get back on track with Sams very useful post.

The issue of adding extra anchors to existing routes was discussed at a recent CNCC anchor installer meeting.
Some of the scenarios discussed there (and previous to the meeting) were anchors at start of a traverse, extra anchors on exposed traverses, anchors to get a better dry hang etc.
My view was that a fresh look (and check) of the most popular caves to see if any extra work was needed to bring them up to a consistent and “current” standard.

Would I personally trust a single resin anchor ?   Yes.
Would I tell someone its OK to use a single resin anchor ?  No

We don’t need to make caving more difficult  / dangerous by the anchor provision.

The CNCC are an “official” caving organisation, any activities it carries out should be considered “best practice”.

On the introduction sheet attached to the topos it states “ For resin anchors you must understand the importance of belaying your rope to multiple anchors, including full traverse ropes leading to pitches”.
The anchors the CNCC provide must allow for this. Alternatively agree that this is not required and remove that wording from the topos.

The CNCC needs to take a position that is mindful of cavers of all abilities and when providing anchor installations has standards and a policy that would stand up to scrutiny at the highest level which I guess (in the absolute worst case) would
ultimately be the coroner’s court.

Obviously all the above are just my personal thoughts.

Thanks for the valuablef and informative responses  :clap2:

Ian


Offline mikem

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Re: Resin bonded anchors
« Reply #33 on: May 17, 2021, 03:06:10 pm »
(On a vaguely related note, I preferred the older rigging topos that included individual pitch heights, rather than just total rope length, as it makes pairing up what I actually have available easier - when they are too short to do the whole thing)

Offline andrewmc

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Re: Resin bonded anchors
« Reply #34 on: May 17, 2021, 03:49:07 pm »
Cavers that are happy with 'more' risk can just skip some bolts and save themselves some gear and rope.
Those cavers who choose 'less' risk, are bringing a group down, are (for whatever reason) more likely to slip can't suddenly produce new anchors if not enough were put in in the first place.

So the bolting should always be a little bit conservative with regard to risk so that the 'average' view isn't imposed on the slightly more cautious where that caution is quite reasonable (like not relying on a single anchor to protect a possible fall). Bolt for everyone (well, almost everyone) :)

Offline topcat

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Re: Resin bonded anchors
« Reply #35 on: May 17, 2021, 08:20:34 pm »

In quite a few cases the risk is minimal to none until you are on the pitch itself, which was certainly the case in Marble Sink where we placed virtually no anchors before any pitch heads because it's all but impossible to fall down any of them until you are on them! I suspect the rationale for Quaking was much the same. With that in mind, I was surprised to see a comment above suggesting there should always be an anchor before a pitch head.


This is often the case in tight caves.  I have been on pitch heads that your worst enemy couldn't kick you down :)
However, a back up bolt / lead inrope is damn useful.  Not for safety as such, but as an aid to getting out.!

 

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