Author Topic: Resin bonded anchors  (Read 1761 times)

Offline s_allshorn

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Resin bonded anchors
« on: May 14, 2021, 03:39:38 pm »
I ask these question as I fear I may have pulled through into a minimalist anchor placement echo chamber that might not reflect how cavers expect anchors to be installed.

Generally, I work to a set of principles for anchor installations for new caves (caves where there are currently no resin bonded anchors) to ensure minimum placements to enable a safe descent, aiming to avoid hazards (water, loose rock etc as much as possible).

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.

So if you can safely and comfortably approach a pitch head where there are no natural belays this would require two anchors. A short but exposed traverse or rift would have two anchors back from the start going out to two further anchors to descend a pitch. Assuming of course there are no natural belays.

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?

b. An example might be there aren't two anchors at the start of a traverse, should/can one be added?

c. If there is a better or drier hang to be obtained further out should more anchors be placed to use it?

d. If there aren’t two anchors to initially go out over a drop or an anchor was installed potentially only as a hand line and has always been treated as such, can/should one be added?

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?

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?

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?

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

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

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

I would invite replies from as broad a range of experiences as possible. If you don't wish to reply to this post feel free to PM me.

Offline PeteHall

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Re: Resin bonded anchors
« Reply #1 on: May 14, 2021, 03:57:38 pm »
A further question I have been considering is this:

If a safe route already exists, is it ok to install new anchors to provide an alternative route purely for sport caving (eg. a more interesting descent or a high level traverse when a passage can be followed at low level).

Offline langcliffe

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Re: Resin bonded anchors
« Reply #2 on: May 14, 2021, 04:17:11 pm »
In general, Sam, I love your anchor-placement style. I think that the Dome Alternative is the apotheosis of minimalist but safe anchor placement.

A few comments:

1. You say "So if you can safely and comfortably approach a pitch head where there are no natural belays this would require two anchors. " I am a little confused by this - do you mean just anchors for the Y-hang? If so, IMHO there should always an anchor at least a couple of metres from the pitch head. I was once a little disconcerted when I got to the top of a small and easy pitch in Flood Entrance, and there wasn't a traverse line to clip into.

2. Two anchors at the start of a traverse: I think that this depends on the risk involved of getting to the second anchor.

3. Better / drier hangs: I think that a better / drier hang does justify additional bolts. I always get a bit cross with the hang on the second pitch of the Rowten Gully Route. Life would be much easier/drier if the hang was further along the rift.

4. "If there aren’t two anchors to initially go out over a drop" - I do not like relying on one anchor. A couple of places spring to mind: the rebelay on the Notts entrance pitch, the rebelay on the ledge on the Marble Steps gully route (although I think one actually pulled out from there), and the entrance to Sell Gill wet route.

5. I think that for the obvious popular pull-through routes, additional anchors ought to be placed if the hard-rigging bolts are awkward to use. I can't, however, think of any examples. Possible an additional higher bolt at Simpson's Slit Pot alternative?

6. If anchors need to be replaced, I have no objection to the line being improved with anchors being placed away from the original, providing that the old line was tidied up at the same time. I think that whilst we are all grateful for all the hard work that the original installers put into placing the routes, times and standards have moved on.

Offline Fjell

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Re: Resin bonded anchors
« Reply #3 on: May 14, 2021, 05:26:59 pm »
A natural or drilled thread as a single belay for the start of a traverse line is probably the most comfortable.

One thing that occurs for me is a need for “balance” in a route. There is little point creating an amazing rig to avoid water if a pitch before or after it is far more flood prone. An example of this is Meregill. What is currently called the 4th pitch is pretty nasty at the top in conditions I would not say were very wet. The route in the rift overhead has not been rebolted. I aborted a ttip at that point last winter. It would be easy to have a bit of an epic at that point if water levels rose when you were below it. The previous pitches are an orgy of traverse bolts (with simpler rigs for dry conditions) It is out of balance.

Online Badlad

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Re: Resin bonded anchors
« Reply #4 on: May 15, 2021, 09:43:41 am »
I think there has been a tendency to over install anchors on the grounds of safety so I am all for a minimum amount to meet the need.  Whatever is done it will not suit all riggers whose preferences might be more, less, higher, lower, etc. but i think it is up to the installers themselves to set out guidelines to avoid proliferation.

There is a conservation requirement at pitch heads as well as safety.  Endless peppering with shiny anchors can take away some of the pleasure of the sport.  The risk of catastrophic resin bonded anchor failure is extremely minimal.  Using two anchors where there is real exposure or danger for the rigger eliminates almost completely that tiny risk.  Other risks and dangers are far more prominent such as the human factor where better training, experience and knowledge are a much bigger factor in safety.

For me, in most situations, if you have a traverse line anchor, whether resin or natural it is not a necessity, on safety grounds, to have two anchors over the pitch head.  A Y hang is far more about the position of the rope rather than a necessity of safety. 

Extrapolate these comments to answer the rest of your questions but basically I would support your minimalist approach.




Offline Rachel

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Re: Resin bonded anchors
« Reply #5 on: May 15, 2021, 09:13:12 pm »
I do wish that people installing anchors made it a bit easier for us short people. Minimal and high for a 6ft person can be impossible/far too exciting for someone nearer the ground.

One example is the start of the traverse in Jingling. The only way I can get to the first bolt is to hold my cowstail in my right hand, put my right toe on a small knobble, then jump out at the bolt in a death defying leap. An extra bolt between the end of the gully and the start of the traverse would probably be considered unnecessary by most cavers but it would stop me and other shorties having to boil wash their caving pants afterwards.

Offline andrewmc

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Re: Resin bonded anchors
« Reply #6 on: May 15, 2021, 10:57:47 pm »
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?

You should always finish with 'satisfactory' anchors (by whatever reasonable criteria you decide to use). If the existing resin anchors are not satisfactory, then they should be fixed.

Quote
b. An example might be there aren't two anchors at the start of a traverse, should/can one be added?

Yes. Forcing people to rely on a single anchor is obviously not good. If you are going to bother sticking a load of anchors in a wall, it should allow you to rig a system that is 'safe enough' from start to finish, and I think most people would agree that a system relying on a single anchor (at a point where a fall is possible) fails that test.

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c. If there is a better or drier hang to be obtained further out should more anchors be placed to use it?

Potentially, if doing so improves the overall route. For example, if every other pitch is death anyway in the wet, a single drier pitch is unlikely to help - but a drier pitch in an otherwise dry cave can be extremely useful. Rigging that is so much harder than the rest just to get a few feet further out is just unlikely to be used (although as a counterexample the traverse in Yordas is actually really good fun despite all being a bit unnecessary). If the newer route means the rigging is safer, or less likely for people to get hung up, then that is an improvement in safety (e.g. the fat person alternative for Slit Pot in Simpson's probably prevents a lot of callouts!)

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d. If there aren’t two anchors to initially go out over a drop or an anchor was installed potentially only as a hand line and has always been treated as such, can/should one be added?

Handlines should be on two anchors. The chance of failure may be lower, but the consequences are often no less catastrophic than on an SRT route. If the current anchors do not allow 'safe' rigging that does not requires commitment to a single anchor, just fix it.

Quote
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?

Potentially - anchors are there for cavers to use, after all, and if 90% of cavers pull through then providing anchors for that is likely to be reasonable BUT that would be a judgement call based on the usage of the cave rather than a hard and fast rule.

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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?

Given that the empty hole can be filled with resin and covered in mud, I see no reason to be bound by the past; but a judgment call for the installer.

Quote
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?

I think this is probably rare? If the anchors are adequate, then just leave them. If they are inadequate, supplement them with additional anchors as required. Then, if the old anchors are entirely redundant, then they could be removed for conservation reasons - but usually I suspect they can just be left.

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

Assuming the rock is still sound and the anchor placement provides for safe rigging, no problem.

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

Anchors are there for cavers to use. If existing anchors are extremely difficult to use, then potentially, yes. E.g. as already described, getting to the first Jingling traverse bolt requires climbing up slime above the last anchor... But not everything has to be easy; just safe.

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

When the job is done - when the anchors provide what is needed, which should _always_ be allowing rigging where you never have to rely on one anchor (where a fall is possible), but beyond that it will depend on the purposes of the anchor and the specifics of the cave itself.

I also think the entrance rebelay in Notts Pot is not OK. The middle entrance of Yordas is quite sketchy given the massive distance between the first and second bolt. There are many others, and I've seen a few places where the 'missing' bolt has been added later! :)

Offline Cripplecreeker

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Re: Resin bonded anchors
« Reply #7 on: May 15, 2021, 11:42:11 pm »
I’m probably in the minority, but I’m more than happy to rig off a single resin anchor. Having redundancy in this part of the system (but no other) seems like a hang-up from the days of spits, rather than a necessary safety precaution.

Offline Cantclimbtom

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Re: Resin bonded anchors
« Reply #8 on: May 16, 2021, 08:42:33 am »
Just for hypothetical fun, based on no real situation...

Is drilling say... a 30cm deep  hole to make a thread, more or less leaving-a-trace than placing an 8.5cm deep (and notched) glue in.

I feel that the thread is somehow cleaner and less impacting although it's a far bigger hole and will grow a bit of in situ kit before long, so my gut feel is probably illogical.

Again, not the purest of ethics but if the rock colour and a popular resin happened to match very closely, does that make moving or adding anchors more acceptable as you can hide empty holes better?
Expert in incompetent tomfoolery

Offline zzzzzzed

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Re: Resin bonded anchors
« Reply #9 on: May 16, 2021, 08:53:25 am »
I’m probably in the minority, but I’m more than happy to rig off a single resin anchor. Having redundancy in this part of the system (but no other) seems like a hang-up from the days of spits, rather than a necessary safety precaution.
Me too.  A single resin bolt below the crux of a difficult sports climb can take dozens of falls a day for years without failing.

Offline Pete K

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Re: Resin bonded anchors
« Reply #10 on: May 16, 2021, 08:57:11 am »
I install and test anchors as part of my work, as well as doing it for the DCA, and to come back on that point from Cripplecreeker - anchors of all types fail from time to time. I've a bag of them upstairs. It is a 100% necessary precaution to have 2 good anchors before you reach the edge IMO. It is what we do as standard in Derbyshire (and of course we also proof-test our anchors to 6kN too).

I don't see any benefit to leaving single anchors in place. It's not like if you install a second one nearby it suddenly becomes an ecological disaster. What is worse - 2 little steel eyes in the wall or the (remote) possibility of a failure leading to injury or death and all the subsequent footfall and litter created by that situation? Yes, one anchor might be fine forever, but what if it is not....?

I was going to write a proper reply to the OP, but I agree pretty much word for word with andrewmc's comments above, so will simply second that!

Offline Pete K

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Re: Resin bonded anchors
« Reply #11 on: May 16, 2021, 09:01:27 am »
I’m probably in the minority, but I’m more than happy to rig off a single resin anchor. Having redundancy in this part of the system (but no other) seems like a hang-up from the days of spits, rather than a necessary safety precaution.
Me too.  A single resin bolt below the crux of a difficult sports climb can take dozens of falls a day for years without failing.
Because it is not receiving a huge load as the rope is designed to absorb most of the impact. Also, if it does fail, there is the next runner below to catch you. Unless you're near the floor then the 'redundancy' of the next anchor down saves you if the top one pops.
The rope and anchor systems here are not really comparable.

Offline Pete K

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Re: Resin bonded anchors
« Reply #12 on: May 16, 2021, 09:03:56 am »
Just for hypothetical fun, based on no real situation...

Is drilling say... a 30cm deep  hole to make a thread, more or less leaving-a-trace than placing an 8.5cm deep (and notched) glue in.

I've done this several times to complement / remove the need for other anchors. If the rock is good then a thread is likely to be bomber forever.

Offline zzzzzzed

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Re: Resin bonded anchors
« Reply #13 on: May 16, 2021, 09:49:42 am »
I’m probably in the minority, but I’m more than happy to rig off a single resin anchor. Having redundancy in this part of the system (but no other) seems like a hang-up from the days of spits, rather than a necessary safety precaution.
Me too.  A single resin bolt below the crux of a difficult sports climb can take dozens of falls a day for years without failing.
Because it is not receiving a huge load as the rope is designed to absorb most of the impact. Also, if it does fail, there is the next runner below to catch you. Unless you're near the floor then the 'redundancy' of the next anchor down saves you if the top one pops.
The rope and anchor systems here are not really comparable.
Yes, you’re right but a falling sports climber still applies a greater force to a bolt than an abseiling caver.  Obviously two bolts are better, partly because they will usually hold the rope away from the rock and prevent rubbing.

I’ve had to abseil off bits of cord threaded into ice holes (abalakov threaders) with water pouring out of the hole, knots jammed in cracks and ancient rusty pitons on sea cliffs so a single resin bolt feels like the Rolls Royce of anchors in comparison.

It’s interesting the differing attitudes to risk between cavers and climbers.  I’ve seen cavers go over the top backing up abseils and adjusting knots for ages only to watch the same person walk up a wet mud slope above a fatally high drop in wellies with no protection half an hour later.

Offline Cripplecreeker

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Re: Resin bonded anchors
« Reply #14 on: May 16, 2021, 10:20:30 am »
I install and test anchors as part of my work, as well as doing it for the DCA, and to come back on that point from Cripplecreeker - anchors of all types fail from time to time. I've a bag of them upstairs. It is a 100% necessary precaution to have 2 good anchors before you reach the edge IMO. It is what we do as standard in Derbyshire (and of course we also proof-test our anchors to 6kN too).

Hi Pete,

I install and test anchors for work too. Personally, I’m happy that the risk of a resin anchor which doesn’t have any visible movement pulling out of the wall is next to zero (I’ll happily reconsider if there’s evidence to the contrary).

I’m not sure that ‘over-bolting’ is really a problem from a conservation point of view, but it does seem like a waste of resources to have twice as many bolts installed in a cave as is really required. Again personally, I really enjoy a minimalist style of bolting/rigging. Having bolts everywhere slightly detracts from the enjoyment of a lot of caves for me.

Offline cavetroll

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Re: Resin bonded anchors
« Reply #15 on: May 16, 2021, 11:09:50 am »
For me, starting a traverse with a single bolt is exactly the same as abseiling the main pitch from a single bolt. The risk is the same, if it fails, you fall down the pitch. Why do we accept it on the much more dangerous approach to the pitch, than on the pitch itself?

Traverses and single-bolt rebelays are probably the thing that make me the most nervous with rigging and beginners. Somewhere like Marble Steps, a lovely cave, has some awful laterally spaced single-bolt rebelays, where if they did fail you'd break a lot of bones even if you didn't snap the rope.

There isn't (to my mind) a logical argument against using two bolts in most circumstances, unless as Sam's excellent set of insightful questions above suggest, there is a suitable natural alternative.

It's perhaps still a feature of caving that some quantity of cavers take pride in how knackered their kit is and how gnarly the gnarliest thing they've ever abseiled off is. Two bolts make it safer UNLESS your harness is from the 60's and your descender has been used to open 4 kegs of beer the night before.. in which case your perspective may well be different.

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Re: Resin bonded anchors
« Reply #16 on: May 16, 2021, 04:13:31 pm »
Where are the accidents that have occurred from properly installed resin bonded anchors failing?  Where are these accidents reported?  Even the so called 'failed' or loose anchors have still taken huge forces to pull out.  I just don't see where concerns over resin bonded anchor failures are coming from?

I do see that there might be concerns over flooding and rock falls as they have caused accidents.  I'm also aware of accidents from the old 'clutch and plummet' of a popular descending device, some fatal.  However, even though there are much safer devices available, such as the ID, I don't see any move to persuade cavers to adopt these safer devices.

Insisting on two bomb proof anchors at the start of a traverse in case one fails doesn't seem to be based on any evidence that failure of this type is a problem.  It only seems based on older, inadequate anchor failures of the past.

If also minded of a common mode failure type issue which can negate a doubling up anyway (should you be concerned of such things).  One of the more likely occurrences of an anchor failure is not the anchor itself but the substrate it is positioned in.  If that fails, ie the rock falls off the wall, then it is just as likely that two anchors will fail as the one.

Above all consider the likelihood of failure of a resin bonded anchor, especially when you've done your visual inspection before using it and go on from there.

Offline Ian Ball

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Re: Resin bonded anchors
« Reply #17 on: May 16, 2021, 05:19:13 pm »
I don't really think I know enough about it all to have too great an opinion, but my general feeling is that anything man made should be the last resort but should be installed in a way that it won't need adding to.

Offline topcat

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Re: Resin bonded anchors
« Reply #18 on: May 16, 2021, 06:19:36 pm »
Maybe the issue in people's mind isn't so much the single resin bonded anchor so much as the single krab or rusty maillon from the club store.  You don't know how many time it has been dropped down deep pitches! :)

Offline Mark Wright

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Re: Resin bonded anchors
« Reply #19 on: May 16, 2021, 06:58:36 pm »
As Badlad asks above, where is the evidence of correctly installed resin bonded anchors failing catastrophically in normal use, or indeed carabiners or Maillons failing.

There’s certainly no evidence of it happening in the rope access industry where they are used significantly more regularly than in caves. Nearly all the fatalities in that industry are caused by ropes failing due to running over sharp edges and the back-up system not working.

From a Likelihood x Severity Risk Matrix Risk Assessment point of view the failure of a single anchor would still be considered a Low level of risk.

Yes, if the single anchor point failed you may well fall and die so the Severity of the consequences would score a 5, but as there is no evidence of them ever failing catastrophically the Likelihood would score a 1.

The Risk Factor can be reduced further by simply being extra careful not to shock load the system, or alternatively, wrapping yourself in a ball of cotton wool.

Mark



« Last Edit: May 16, 2021, 07:13:44 pm by Mark Wright »

Offline Fjell

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Re: Resin bonded anchors
« Reply #20 on: May 16, 2021, 09:26:17 pm »
As Badlad asks above, where is the evidence of correctly installed resin bonded anchors failing catastrophically in normal use, or indeed carabiners or Maillons failing.

There’s certainly no evidence of it happening in the rope access industry where they are used significantly more regularly than in caves. Nearly all the fatalities in that industry are caused by ropes failing due to running over sharp edges and the back-up system not working.

From a Likelihood x Severity Risk Matrix Risk Assessment point of view the failure of a single anchor would still be considered a Low level of risk.

Yes, if the single anchor point failed you may well fall and die so the Severity of the consequences would score a 5, but as there is no evidence of them ever failing catastrophically the Likelihood would score a 1.

The Risk Factor can be reduced further by simply being extra careful not to shock load the system, or alternatively, wrapping yourself in a ball of cotton wool.

Mark

A fatality is always in the ALARP region so you are obliged to take all reasonable (and often unreasonable) measures to reduce the probability. Using two belays in a single-rope situation is not only plainly within the realms of reasonable, it is in every manual.

For me it is extremely simple - I am not going to expose my wife or friends to easily avoidable risks.

Legally you are just toast if there was an incident, and I am not sure insurance would stand up to it either. I imagine it would be childs play to portray as gross negligence - and widows, orphans and lawyers gotta eat.

I buy a 200m reel of rope about every year to rotate the stock, and have pretty much fixed on using 10mm in the Dales given you need about 250m at most, and usually much less. That 10mm Teufelberger is pretty good value, so what excuse do I have? When used with P bolts I am intensely relaxed and even chillaxed about gear failure. I am less sanguine about flooding given that sort of thing has happened to me, let alone "in the industry".

Then again, the "once in a million years" top event has also happened to me - it just proves you don't know about the unknown unknowns etc. Only the paranoid survive.

Offline MarkS

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Re: Resin bonded anchors
« Reply #21 on: May 16, 2021, 09:48:22 pm »
In general I think that a (sensibly) minimalist approach is absolutely the right one. Sam, I don't think you are in an echo chamber at all.

While I was installing resin anchors in Mayday Hole yesterday I was pondering the school of thought about 1 vs. 2 anchors to start a traverse, but I think it's an illogical question in most situations. More often than not there is not a spacious and immediate drop down a pitch i.e. it is not black and white as to where a rope is needed or not needed on the approach to a pitch.

Putting 2 anchors at the start of a traverse because "a rope should always be connected to 2 anchors" is a bit odd given that it's subjective as to where a rope is even needed at all. Viewed another way, moving 1 of your 2 initial anchors back from the danger makes a route safer than starting a traverse with 2 adjacent because it gives 1 anchor rather than no anchors on the approach (and I suppose also reduces the risk of substrate failure affecting both).

Anyway, as has been stated above, it's all pretty academic given the failure rate of resin anchors.

Offline andrewmc

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Re: Resin bonded anchors
« Reply #22 on: May 17, 2021, 12:04:48 am »
Putting 2 anchors at the start of a traverse because "a rope should always be connected to 2 anchors" is a bit odd given that it's subjective as to where a rope is even needed at all. Viewed another way, moving 1 of your 2 initial anchors back from the danger makes a route safer than starting a traverse with 2 adjacent because it gives 1 anchor rather than no anchors on the approach (and I suppose also reduces the risk of substrate failure affecting both).

Which is why I said you should never have to rely on a single anchor _where a fall is possible_. So if the first two anchors are far enough back, all is well. And as you say, putting that first anchor further back reduces the chance of shared rock failure.

Rock failure or installation failure is, I agree, far more likely than anchor failure itself.

Basically, if you are going to bother bolting it in the first place, why not do a good job of it? An extra anchor is going to make no real difference from a conservation point of view.

Offline alastairgott

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Re: Resin bonded anchors
« Reply #23 on: May 17, 2021, 12:08:21 am »
wrapping yourself in a ball of cotton wool.

(Off topic :chair: ) but Apparently cotton wool makes a good firefighter when mixed with Vaseline (petroleum jelly) :blink:   :dig:




Offline Pete K

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Re: Resin bonded anchors
« Reply #24 on: May 17, 2021, 05:59:00 am »
Ensuring that you are past 2 anchors before being exposed to the drop, whether they are 2 together or 1 after the other, was what I meant. Not religiously starting with Y anchor each time. On a recent bolting project we have installed 2 anchors like a sideways Y hang at the traverse start because you are exposed to a slippery and substantial drop shortly after. On another project we placed a single anchors in the approach and then another just before the drop, so at the point you are at risk you have 2 anchors in the system.
I don't think the anchor is going to fall out the wall, I've pulled enough out to know how strong even loose ones are, but they do come out in the lump of rock they were placed in sometimes. We can do a 100% by the book job of installing in natural stone, and still see a failure in the anchor linked to the substrate letting go. Rare to be sure, but take a look in Pearl Chamber in Knotlow.

I don't disagree with the opinion that a single resin anchor is highly unlikely to fail, but I do prefer to be certain that 2 definitely won't.

 

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