More force testing on 5:1 systems

This post follows up on some initial testing done on 5:1 mechanical advantage systems used to tension tyrolean crossings done a few months ago. I suggest anyone who has not read that report catch up with it here before reading on as I don’t explain everything again here.

For this batch of testing I used the same site but rigged things using metal strops instead of rope loops. This would act more like the solid bolt anchors used underground and would nearly eliminate false readings from knots tightening.

I used 2 types of readily available Type A rope

  • 11mm Mammut Performance semi-static
  • 10mm Beal Antipodes / Industrie

The tests were repeated with 3 different progress capture devices

  • Brand new Petzl Stop (rigged both fully and half threaded)
  • 10 year old worn Petzl Stop fully rigged
  • Brand new Petzl RIG

I created a 5:1 system on 10m section of rope using a Petzl Ascension jammer, Petzl Tandem pulley and a Petzl Partner pulley. These are all items that would likely be used by leaders underground or of similar type. No big rescue pulleys or prussics.
I pulled all of the tests on my own with un-gloved hands. I weight approx. 90kg and pulled as hard as I could using just hand grip.
The final tension in the line was estimated by hanging off it and the force on the jammer ascertained using a Rock Exotica Enforcer load cell measuring in kN.

11mm rope

New Petzl Stop – fully rigged
2.06kN
2.10kN
New Petzl Stop – half rigged
1.96kN
2.04kN
Old Petzl Stop – fully rigged
2.04kN
2.04kN
Petzl RIG – belay mode
1.94kN
2.08kN

10mm Rope

New Petzl Stop – fully rigged
1.88kN
1.88kN
New Petzl Stop – half rigged
1.70kN
1.82kN
Old Petzl Stop – fully rigged
1.98kN
1.92kN
Petzl RIG – belay mode
1.78kN
1.80kN

There clearly was a drop off in force required to tension a 10mm system over the 11mm system, although only small. The fully rigged Petzl Stops required the highest force to tension although the old Stop in the 10mm test oddly required more than the new one (*see foot note).

I took the highest force generating configuration and added some more people to the pulling end.

11mm rope with a fully threaded brand new Petzl Stop

2 smaller adults pulling
2.00kN
2.22kN
2.34kN

2 small adults & myself pulling
3.56kN
3.24kN
3.54kN

I think it is entirely possible to exceed the 4kN figure if 3 large and/or strong adults were to be pulling on a 5:1 tensioning system. Both ropes used were clean and supple, with a dusty rope friction would again increase and coupled with some less efficient pulleys might tip the force higher still. I think that it is still appropriate to give out the advice that no more than 2 people are used to tension 5:1 systems, perhaps 3 if using youths or very small adults but certainly no more. The force required to damage a rope at the teeth of the jammer is rather large, especially on 11mm rope, but repeated tensioning on the same spot in the rope may, over time, lead to degredation of the rope.

The best advice I can give is to echo what is already taught at LCMLA and CIC:

  • Keep your pulling ratios at 5:1 or lower and don’t exceed 10 men equivalent pulling power. i.e. 3:1 with 3 pulling or 5:1 with 2 pulling.
  • Keep ropes clean and supple.
  • Use only Type A ropes compatible with your choice of progress capture device.
  • Thick ropes are stronger and stretch less but require more force to initially tension.
  • Thinner ropes are strong enough but stretch a little more and require less force to initially tension.
  • Where very high tension systems are required consider doubling up on ropes and using a non-toothed rope clamp like a prussic or Petzl Shunt / Rescuecender.
A final thought. It is only a short period that the tension is applied to the rope via the teeth of a jammer in these set ups. It is the resultant tension and forces in use that are just as, if not more important to keep an eye on. Tensions in tyroleans can easily exceed 2.00kN, the maximum load Petzl advise for a Stop descender. Consider all components carefully and practice safely before using for real.
* Having given this some thought I believe that I can explain the added friction for this configuration. Over its life, the older Stop has been used for many miles of 10mm rope, wearing the alloy bobbin into a matching profile. Now there is a larger contact area between the alloy and the rope when compared to the brand new Stop. The larger contact area requires more friction to overcome and hence the greater force required to pull the rope through.
2 Stops

Review – Petzl Club, semi-static rope

I had an email about a month ago from Shaun at Hitch n Hike. He’d been sent a 70m sample rope from Petzl to evaluate and once it came out of the box and he saw the colour, he knew who to call.

20151215-0000 Club 10mm pt1This rope was a 70m coil, sold in an un-shrunk condition. Rather uniquely I think, Petzl will be supplying this rope with an additional 10% of length over the advertised sale length. This is to ensure that the shrunk length is not shorter than the labelled length. So if you buy 70m, you receive 77m.
20151215-0000 Club 10mm pt2There are no sold prices advertised as yet but a conversation with Shaun indicates that this rope will come in a little below the similarly spec’d Beal Antipodes 10mm which is so popular as a caving rope.
We opted to reduce the 70m length to a 25m and 45m, both of which were of course 10% longer pre-shrink due to the generous measuring of the manufacturer.
I washed and shrank the rope before allowing it to dry naturally as per usual preparation methods.Petzl Type A rope

The rope is a fierce shade of orange and in the hand feels supple and easily knotable. This characteristic made for pleasant use and did not deteriorate with a month’s heavy use. It was used in SRT rigging and group management with Italian Hitches and was easy to use in all knotting applications.
The feel is quite like a floating rope as seen in throw lines, sort of hollow. Although a normal kern-mantle construction, the rope would compress down flatter as it moved over karabiners and more importantly, through a Petzl Stop. I don’t have a brand new Stop but it could not be described as heavily worn. The rope crept through the Stop in most applications, including haul and belay. I did have the opportunity to abseil using a Petzl Pirana canyoning descender and found it was a really nice abseil. I suspect this rope has been designed more with those type of descenders in mind.
The rope gets pretty heavy when wet but the water does not adversely affect the handling, certainly no more than any other. It’s been dragged through mud, slate dust and water and still cleans up well.
The rope packs into tackle bags well due to its suppleness but it this does cause a problem for SRT. It does not push well through ascenders and requires some manual feeding at times when a stiffer rope would be pulling through on it’s own.
It does feel quite heavy for it’s size. I’m sure on paper it won’t be much different from Beal or Mammut equivalents but to me it felt heavier than most of my other ropes of similar lengths.

Over the last month the rope has been used as an SRT line, Level 1 handline and belay rope, a ladder lifeline and as a hauling line for rescue. It has been used by me, friends, other instructors and course students.

I like this rope. It is nice to handle, bright and has a good feel. I won’t be purchasing this line for SRT, it is not the right rope for that. I think this is a rope designed for canyoning, where descents are done on figure eights and not generally assisted breaking descenders like Stops. I’d own a few lengths for group work through. It’s nice handling and tough feel would make it a pleasant Level 1 rope. In summary, this is nice stuff but perhaps not as an SRT caver’s rope.

Can you cut rope with a household jet washer?

After the last blog post where I tried to compare washing a caving rope in a washing machine to jet washing I thought I’d try to see how much damage I could do to a rope with a jet washer.

This photo was from the previous test where I exposed the rope to a full power, fine jet for approximately 30 seconds.OLYMPUS DIGITAL CAMERAI could not see any evidence to say that the rope had been damaged by the jet wash exclusively. The longer fibres shown here could have been the result of the already cut fibres in the sheath (short cut sections showing) being forced out from under another braid. Of course, the damage may be down to the jet wash alone. I think the only real way to progress with this test is to take a piece of brand new rope and jet wash it. I don’t have any laying about right now so I did some more testing with the leftover Beal Antipodes 9mm from the previous testing.

I split the rope down into various grades, from single bundles to cotton size filaments.Anatomy of a ropeI hypothesis that the worst case scenario is a rope being jet washed up against a solid surface whilst under moderate tension. The tension would keep the rope in the jet longer and the solid backing would provide a surface for the fibres to be crushed against or even abraded. It had occurred to me the damage could come from the power of the jet rubbing the rope against a course material.
The backing for this test was a piece of porcelain tile, almost completely smooth to the touch. The tile sat between the rope fibre and the wood in the test device I knocked up.Test assembly v1I tested each size of bundle on both full power and the normal setting that I use for washing. Both jet setting were fired at point blank range into the fibres for 60 seconds. This test was repeated at least twice for each sample after it was checked close up.
This sample had been washed on high power/very tight jet for 120 seconds. The jet was directed at the same area of the sample for all the test time. For scale, the fibre here is about size of that very tough cotton used for stitching canvas and kit bags together.One strand

The fibre bundles became so small that I could easily break them in my hands. This one was no bigger than a piece of cotton.Cotton thinkI figured that if my jet wash could not cut through a piece of sample that was thin enough to break easily with my hands then I did not need to progress onto smaller samples.

Conclusion?

As before, I need to state that this back garden test does not give a statistically sound result and as such only serves to show what occurred in this one instance of testing.

I could not get my jet washer to cut any size of sample on this test. In both high power/confined and low power/wide spread modes, I saw no damage to the rope fibres. No doubt individual filaments of the fibres may well cut very easily but they break with the slightest of effort in the hands anyway so I doubt the value of that observation. The cotton size sample was the smallest test size and even that could be broken by hand with little effort.
It is also worth noting that this experiment was done on a 7 year old rope that had seen high use in very abrasive environments over its life.

Challenge

I’d really like for other cavers to go out and try this experiment for themselves. Take a small piece of old or new semi-static caving rope and split it down to various sample sizes. Use a domestic jet washer / pressure washer on it’s highest setting and see if you can cut or damage the sample. For consistency, do it in 60 second, point blank range bursts.
Let me know via the contact address on my website or via the thread on UKCaving what happens. Failures to cut are just as important as actual cuts, so let me know either way.

Thoughts on jet washing caving ropes

I thought I’d ponder a little bit about the ‘myth’ of jet washers and caving ropes. I say myth because it appears that there is no real test data out there in the caving community. Recent caving forum discussions about jet washing happened to coincide with an associate company requesting we don’t use jet washers on their kit earlier this week and the two events spurred me to type something up.

Disclaimer – This is not a scientific, empirical experiment and you should always follow the care instructions of the equipment manufacturer.

I have used all sorts of methods for washing ropes over the years and most of my older ropes have been subjected to each at one time or another. Some times a rope may simply get dunked in the stream by the cave, other times I see fit to pull it through my home made rope washer but, more often than not, I get the jet wash on them.
The jet wash is always set to its lowest power and widest spray pattern. I’ve caused real damage to wood and clothing before by using the jet wash on full power so I am cautious. Some site this as the reason you should never use a jet wash on ropes. I agree. If you don’t know how to wash with a jet wash don’t do it. That, and if you don’t know how to operate your washing machine and it ends up on a boil wash, you probably shouldn’t put your ropes in there either.
This Beal 9mm got a super fine jet of water for about 30 seconds at point blank range in a test today. Damaged Rope

Apart from being incredibly clean for a 7 year old rope, you can clearly see the elongated sheath fibres. I’m not convinced the jet wash cut any fibres, more that it simply forced the already cut and abraded fibres out from under the other braids. The core was not exposed. I’d not want to do this to my ropes ever but I would call it far from ‘cut’ or ‘shredded’ as some anecdotal tales from the web recall.

Moving on. The rope I chose to retire was a Beal Antipodes 9mm semi-static that I purchased in 2007. The rope was one of my main users for 3 years as a 40m before being cut into 2 shorter lengths for cave leading handlines and general Italian Hitch duties. For the last 2 years it has languished unloved in the shed and has been the subject of much abuse in non life-critical applications. It’s probably not been washed for a year but before that it saw regular jet washing and stream dunking.

I cut the length in half and removed a control sample from either piece. The two 1m control sections came from the very end of the rope, where it was marked, and roughly half way along the 20m length respectively. I single daisy-chained one 10m length and double daisy-chained the other.

Test rope setup

The 2 longer lengths were soaked in cold water for 10 minutes as a pre-treatment.

As this was happening I cut open the 2 control lengths for a comparison.

End of rope section:Mid rope inner sheathEnd reel control Mid rope section: OLYMPUS DIGITAL CAMERAMid rope inner

The 2 samples looked very similar and I’m happy to say, despite years of being jet washed, were relatively clean and un-abraded inside. The fluffing you see was caused by the cut into the rope.

I dropped one of the test lengths in the washing machine. I set it to ‘delicate’ on a cold wash with no spin after first running a rinse cycle to clear any detergent. It had a 62 minute wash time.
While this was going on I jet washed the other test length in the same manner I do all my ropes. The process took approximately 5 minutes and once complete the rope was allowed to drip dry until the washing machine had completed it’s cycle.

After washing After washing

In both photos the washing machine cleaned rope is at the top and the jet washed one at the bottom.
I think it’s clear to see from the photos, and certainly was in real life, that the jet washed rope was far cleaner than the machine washed rope. It also had a much suppler feel and was more knotable over all. Remember the ropes have been identically treated until this very last wash in this test.ComparissonThe rope on the left is the machine washed and the one on the right has been jet washed.

It is hard to draw conclusions from the comparison here as this is only one wash cycle. The jet wash seemed to get the better results in terms of appearance and suppleness but the internals of the ropes looked very similar.
The one thing that I do take from this test is that despite the differences in the test washing, all the samples from this rope did not show any appreciable abrading of internal fibres from grit ingress. The anti jet wash argument is that the force of the water pushes grit into the core, causing damage. What I observe here is that this is an incorrect assumption as the 4 sections of visible inner on this very old, well used and heavily jet washed rope show no signs of damage by internal abrasion.

My theory is that the jet washing forces the grit and mud through the core and out the other side of the rope, as opposed to moving it into the core and it magically stopping there. I always clean my ropes after each trip. Perhaps they simply do not stay dirty long enough for the grit that does enter the core to be damaging. The outer sheath shows far more wear and damage than any of the internal structures of the rope.

I continue to believe that regular low-power jet washing does no harm to my ropes. I do know that some manufactures do not suggest using a jet wash on ropes and you should make your own choice with reference to the manufacturer’s guidelines. I will continue to cut open ropes as they are retired and will update this blog should my opinions or observations change. Meanwhile, if there is anyone out there prepared to take this subject up for a dissertation or just for interest then get in touch!

Gleistein GeoStatic NE 9mm rope – 18 months use

It’s now March 2014, about a year and a half after I bought my first length of the Gleistein Geostatic 9mm rope.
The 31m length I bought was soaked at home and measured to 32m, no doubt down to Shaun at Hitch N Hike’s generous measuring style!
I labelled it up as a 30m and went about using it.
I re-measured it today and it came in just over 29m, a shrink of 3m since initial cutting, approx. 9%. So it seems, just like any other rope, once it’s cut you still need to factor in about 10% for shrinkage over the life of the rope. I’m still happy because there was no noticeable shrinkage after cutting and soaking when first purchased in Sept 2012.

I have a 21m length bought about a year ago that has just re-measured to 19m. This length has had a hard life already, it is my traveling rope on cave leading work and has been dragged through numerous Italian hitches whist being covered in grit and the particularly abrasive mud in Peak Cavern’s trade routes. It has done a good job at sawing through my alloy krabs but the rope itself is still in excellent condition. There is some light fluffing on the sheath comparable with some of my far less used ropes and the colour, like the 29m length, has faded into a more pastel orange. It still handles extremely well, clearly not as supple as when new but a massive improvement over the 2-3 yr old Mammut 9mm I have, which is more akin to wire cable now.

My cleaning regime for all my semi-static ropes is simple and it gets done after every trip. For clean trips it is just a spray with the hose or a dunk in clean water to remove particles from the surface. More often than not it gets a low power jet wash (controversial I know!). Never force dried, only hung in a spare room or over the bath.

I’ve got 3 lengths now, each bought about 6 months apart and will continue to purchase this rope as my current ones approach retirement.
In another year and a half, when this rope is no longer in service I’ll do a final post mortem report. I’d also like to send a few samples to be tested by the BCA and Bob Mehew to see what toll the hard life has taken on it.

Gleistein is still available at Hitch N Hike as cut lengths or entire reels: http://www.hitchnhike.co.uk/acatalog/gleistein-9mm-geostatic-ne.html

The initial blog post is here: http://www.peakinstruction.com/blog/first-look-at-gleistein-geostatic-ne-9mm-semi-static-rope/

Conclusions on the use of the BotB

So, the footage has circulated, tests have been done and reports and statements have been published. Where are we on BotBs?

I echo the BCA advice that the BotB is safe to use provided that a cowstail is always clipped into both loops. I will continue to use the knot in my range of personal and professional tools. I think that the knowledge of this method of failure has been there since the BotB came into use, I do think that a number of people were shocked as to the extent of the failure when they saw it. This knee-jerk away from the BotB has calmed down as people have looked into the evidence and scenarios of failure.
Hopefully enough information is out there now to allow cavers to make their own choices on knot application.

A concern may crop up for some riggers where they are leading less experienced cavers or those who simply do no know about the single loop issue. The rigger may descend the pitch and those following could inadvertently clip a single loop placing them at risk of this failure. This scenario perhaps would benefit from the use of a knot that won’t fail if a caver clips a single loop – However the advice to clip both loops does not change.

What if you don’t want to use BotBs?

Well, a number of suggestions have been put forward.
The Fig 8 ‘Bunny Ears’ / Double Fig 8 on the Bight is the most common knot but lacks the ease of adjustment and untying that the BotB has.
The Fusion (Karash) Knot is simple enought to tie but is a struggle to dress on stiff rope and has zero history in UK caving prior to a few months ago.
Alpine Butterflys or Caver’s Butterflys can provide a good Y-hang but an overhand knot would need to be introduced to one of the loops to give a central rescue point.
The Double Bowline on the Bight is one extra twist from the BotB. It adjusts, ties, unties and looks like a BotB, meaning it is easier to use and spot mistakes for existing BotB users.

The choice is down to the individual rigger. The evidence is out there for you to see.

Warning – correct use of Bowline on the Bight Knots

BCA’s Training and Equipment & Techniques Committees would like to highlight the importance of ALWAYS clipping a cowstail through BOTH loops of a Bowline on the Bight knot. Although this has been taught for years by BCA instructors, it appears
that many cavers are not aware of the importance.

The problem is that in a fall the knot can slip in such a way that the rope going down the pitch can actually run all the way back through the knot. This means that a caver falling
at a pitch head with their cowstail clipped into only ONE of the two loops could
potentially plummet all the way to the bottom of the pitch. This cannot happen
if they are clipped into BOTH loops.

A useful tip is for the rigger to leave an HMS karabiner clipped between the two loops to make it easier for the rest of the party to clip in and it is always worth remembering that two cowstails are preferable to one.

From here: http://www.british-caving.org.uk/?page=150

The report from drop tests at BPC on the 30th Jan 2013 is here: http://british-caving.org.uk/equipment/Initial%20results%20from%20a%20Preliminary%20Investigation%20into%20Y%20hang%20knots.pdf

UKCaving discussion here: http://ukcaving.com/board/index.php?topic=14602.msg191183;topicseen#new

2nd round of testing on the Bowline-on-the-Bight knot

Thinking that 2 heads were better than one I set out today with a good friend and colleague, Jez Parr. Jez in another CIC holder with many years of experience. He was also my mentor through the CIC scheme and the ideal person to bounce ideas off.

Our first stop was local gear shop and purveyor of lovely shiny things, Hitch N Hike. We purchased 5 metre lengths of all the most commonly used semi-static rope they had, in both 9 & 10mm.

The test was set up identically to the ones done previously on the 8th Jan. We had a mock Y-hang arrangement that allowed us to position the test ropes at varying heights and angles as well as a solid bar from which to rig a secure dynamic safety back-up for ourselves.
The aim of the first testing done previously was to identify the main contributing factors that caused the failure in the Bowline-on-the-Bight, or BotB. This was achieved and we could generate failures almost 100% of the time. This test is written up in the last blog post.
Today’s testing was all about trying to get a failure in a normal use environment with normal conditions. All the tests we did were on knots that has been tied, dressed and set as we would and have done thousands of times underground. We were not wanting to tie sloppy knots, we wanted to see if it would fail when it was done well.

Results:

For every test of every rope in every combination of orientations we tried, so long as the cowstail was attached through both loops of the knot there were no failures. This was as expected and ties in with the best practice advice that has been taught for years with the use of the BotB – ALWAYS CLIP BOTH LOOPS.

For tests carried out where we dropped onto a single loop – the one formed from the traverse line or stopper knot, we could also generate no failures. However this is outside the intended use of the knot so little time was spent investigating that scenario.

When connected to the Bowline-on-the-Bight with a cowstail attached to the single loop formed by the pitch rope we were able to generate failures in knots that were tied and dressed correctly that had been hand tightened or on occasion body weight tightened.

Below are a pair of images showing slip through the knot. Note the blue mark.
BotB test 3

BotB test 4

A second set of test images:

BotB test 1OLYMPUS DIGITAL CAMERA

For a YouTube film of 3 of today’s tests see here: http://youtu.be/Kpd7RF1ybgI

For the previous test film see here: http://youtu.be/-5-YbRxceiY

Conclusions:

The Bowline-on-the-Bight can fail when you are clipped into a single loop and the knot is dressed correctly and tightened. The failures we generated included ones where we both agreed that we had tied a perfectly acceptable BotB before testing.
Although we can identify many modes in which we could not get a failure to occur, the fact that one can occur in normal* use is very worrying.

* normal use if you only use one loop to attach your cowstails as is against the best advice – always clip through both loops!

So now what?

Cavers should draw their own conclusions from these tests or indeed conduct their own perhaps.
I believe that it is still appropriate to teach the Bowline-on-the-Bight as one of the standard knots for caving alongside the information about how to use it safely and the consequence of misuse.
I will copy this information to the British Caving Association for review. It is not my place to advise on caving policy for the UK.

I have been offered the chance to use a rope tester to look at potential replacements for the BotB. The test will give us a chance to see how a replacement compares with the existing methods in terms of strength and durability.
The French’s preferred option – the Fusion Knot, which has also been called the Karash Knot, is high on the list of contenders but I feel that a similar knot to the BotB would be more easily absorbed by the caving community. Both myself and Jez think a closer look at the Double-Bowline tied on the Bight may give a very good alternative. We’re calling it a D-BoB, or Double Bowline-on-the-Bight, until we can establish its correct name.

Testing a method of failure with a Bowline-on-the-Bight knot

A recent video clip has come to light on UKCaving Forum from the French Caving School which identifies a method of failure for the Bowline-on-the-Bight knot. The School’s film shows a failure that could lead to serious injury or even death when clipped into only one arm of the Y-hang.
I have not seen or heard of any occasions where this failure has happened in the U.K. and have certainly not seen it with my own eyes until today’s tests. It is rare for such a statement to come in regards to such a well used technique so I had to investigate.
We made use of the excellent training facility at Pindale Farm in the Peak District and the not so excellent weather.

Background:
The Bowline-on-the-Bight or ‘BotB’ knot is widely used and taught as a preferred knot for most SRT rigging applications involving Y-hangs and SRT. The knot has certain shock absorbing and self equalising properties that make it a good choice. These traits form one side of a double edged sword, the other side being the knot is easy to undo and therefore easier to loosen in use. It is this property of the Bowline knot family that can lead to slipping failures like the one we are looking into here.
For anyone who does not know the BotB knot, I will not explain it here as there is a wealth of literature and information on them online. Spend 5 mins Googling or pick up a copy of a UK caving manual.

The Failure:
The problem occurs when a caver is clipped into one arm of the Y-hang formed by a BotB. The two arms are formed from different parts of the knot, one coming from the pitch rope up into the knot, twisting round and emerging to form a loop and the other from the traverse line or on occasion a stopper knot.
Being clipped solely into the arm formed from the pitch rope can cause the rope to pull through and effectively untie the knot when loaded by the caver. If on a straight pitch with no other attachment the caver could fall to the floor. Even with a re-belay or end of rope knot present to stop the rope being pulled totally up the slip can still occur. I ruined a length of rope today, wearing through the sheath on a slip of less that 2 metres.

Observations:
We managed to work through a set of differing conditions and factors to arrive at a scenario where we could generate an almost 100% failure rate. We used the same rope throughout the tests, although the knot was tied in different sections to prevent too much damage to the same area.
The rope was a 5 year old length of 10.0mm semi-static rope widely used by cavers. We also tested a length of smaller diameter rope from another brand with similar results. The rope was stiff but could still form and hold a knot well.
We varied the knot for each test in the following ways:

  • Dressed correctly or not
  • Tightened or not
  • Evenly loaded or not
  • Clipped into left or right arm
  • Clipped into both arms
  • 10 & 9mm rope tested
  • Wet and dry

In the outdoor world we use a accident analogy called the ‘Lemons’. If you imagine a slot machine is your work and the tumblers and their ‘fruits’ are the chance of events happening, the lemons are the poor practice, bad judgement or bad events.
As a lemon appears on a tumbler it is usually outweighed by a good fruit, i.e. a bad thing/poor practice is safeguarded by the other good practices along with it and the chance of an accident is low.
When all the lemons come up on a line together we have a series of poor decisions or events that collectively form a chain of events and choices which dramatically increase the chance of having an accident.
It is this analogy that I think fits perfectly with this method of failure in the BotB.

When the following conditions were met we experienced a near 100% failure rate.

  • Wet rope (very high rate of failure on dry too)
  • Knot not fully tightened
  • Y-hang arms not equally loaded – specifically the one formed by the pitch rope
  • Caver only being clipped to the loop formed by the pitch rope
  • A dynamic fall similar to someone slipping on the lip of a pitch
  • Knot recently tied – i.e. first person down after rigging.

It is worth noting that we did have other failures with different test conditions but on a far smaller percentage of tests. The loose arm being the common factor in all of our testing.

Bowline-on-the-Bight test – YouTube

Best Practice:
We teach what is known as best practice. This ideal of coaching changes and we are constantly evolving our advice. This is one of the reasons I went and did these tests today, to ensure that what I did was still the best it could be.
Current best practice advice for SRT, rigging and progression where relevant to this article is as follows:

  • Rope used should be of good condition and supple enough to hold a knot well
  • The rigging should be tight and all knots dressed correctly and tightened down before use
  • Y-hangs should be loaded equally
  • The caver should always have their cowstails clipped into both arms of Y-hangs (you’ll notice we use larger krabs than most for this reason)

Conclusions:
We experienced no test where a failure occurred when all of the best practice conditions above were met.
Failures did occur in other tests, the chance was lower unless all of the ‘Lemon’ factors were involved.
I suggest that anyone with genuine concerns seek advice and, of course, under no circumstances should you use a technique that is unfamiliar to you. Get trained, get experienced, get informed.

First Look at Gleistein GeoStatic NE 9mm semi-static rope

Here is a quick set of initial observations on Gleistein GeoStatic NE semi-static rope. A full write up will follow in the future.

So, a few weeks ago I was chatting to a caving friend of mine who has turned outdoor gear importer/supplier and was told about a new type of semi-static rope available in the U.K. The reason this particular rope caught my attention was down to it’s specs, the sheet described a 9mm rope with full Type A certification and a strength exceeding that of Beal 10mm Antipodese, I had to get some!
The rope in question has just landed at Hitch n Hike in the Peak District and I ran down there today after work to collect a length for testing. What I’ve got here is just a few initial observations for the interested caver.

Length:
I was aiming for a 30 metre length after shrinkage so was expecting to be buying around 34m today. An examination of the GeoStatic data sheet showed a shrinkage of only 0.7%, thats 70cm in 100m! The rope must be pre-shrunk before being placed on reels to get a figure that low. I opted for 32m to be on the safe side.

Edit – It’s now March 2014, a year and a half after buying. I’ve just re-measured this rope and it is just over 29m, a shrink of 3m since purchase. This is a shrink of about 9% in longer term use. For comparison I also re-measured a length of Beal Spelenium Gold which had shrunk from 32m to 27m over its 3 year life so far, 15.6% shrinkage from the cut length.

Handling & appearance:
You are in no doubt that it is a 9mm rope, a coil of 31m looks like it could fit in a handbag, a significant size reduction on the Mammut Performance semi-static I generally use. It handles like a supple dynamic half rope, bending almost flat as you make a teardrop in your hand and not feeling at all stiff as you turn it to form knots.
The rope is apparently manuractured in a number of different main colours, all with a common single white line woven spirally. The colour currently available from Hitch n Hike is orange, so would not look out of place underground alongside the current Mammut orange rope (+double black fleck). Other colours like blue may result in people asking if you are using dynamic rope!
The single white band corresponds with the generally accepted method of identifying 9mm ropes with a single line of flecks – Beal use a single line of red and black and Mammut a single black line.

Preparation for use:
As with all new ropes, the first thing I do is soak them in a bucket of water. This serves a duel purpose, allowing the rope to shrink and washing any residue of the manufacturing process off (that slippy white liquid). The shrinkage I will measure and report back on. The rope appears to have been pre washed and shrunk because after one hour there has been no discolouration to the water. The rope’s colour changes to a nice dark shade of orange once wetted, a small point but you’d easily be able to tell if it was dry.

Next step:
I will leave the rope to soak over night and hang to dry tomorrow. I will measure the length to the nearest half metre and mark it up with gear tape.
I’ll be using the rope as much as possible in the coming weeks to get a real feel for it. After a dozen or so uses I’ll remeasure it and report on any further shrinkage.

I’ll put up a more in depth reveiw of the rope after I’ve used it a bit more, but for now the manufacturer’s site is here and the Hitch n Hike site is here.

Specs:
Gleistein GeoStatic NE 9mm
4% stretch
0.7% shrinkage
39/61 sheath to core ratio
27kN breaking strength (epic)
54g per metre