BCRA/BCA Drop Test Results

[SamT]

My google foo seems weak - cant find any results online anywhere.

Are there any results published online..

Its in an answer to the following posted on a climbing forum regarding lower offs/belays at the top of routes - usually round a tree/boulder -

What is the evidence of static rope (nylon kernmantle) decaying in this way?
Obviously sharp edges pose problematic for fabric ropes but nylon kernmantle ropes are very, very durable with respect to UV, water (in static situations), etc., etc.
Generally mould or rot will occur on organic matter that has got into in-situ fabrics but I've not seen evidence that this will meaningfully damage a 10mm static.

Which is a bit of an alarming post if people have this impression.  Or maybe they're right.
Though to be fair they backed it up with..

My post was a "call for evidence". Preferably not hear-say.
UIAA standard 101 / Ropes states: "It is sensible to avoid strong light and extended exposure to UV rays, although there are no known
instances of a rope failing due to UV degradation, since the core is protected from UV by the sheath."

Would be good to point them in the direction of some results that old static rope, thats been in the dark for years, away from organic matter, can still snap at low loads.  (or not).

 

[SamT]

Further more - are there any comments from the high access boys - Wardy/Mark etc about static left 'insitu' and UV degradation etc.

 

[Bob Mehew]

There has been some testing on used ropes and yes they do degrade when left underground.  Some of the work was put up on the web but it has now been lost following the loss of the web sites.  (The Way Back machine will show up one piece of work from the previous BCA web site as on 11/8/20.)  Simple conclusion - caving deteriorates rope much faster than climbing.  (My thought was it was due to washing out the oils in the rope.)  Worked has ceased since:
        a) I resigned from the post of BCA Rope Test Officer early this year,
        b) the mobile rig is back with BCA, and
        c) regrettably the Bradford rig was demolished when they took down their old garage. 

PS - anyone want to take the topic over?

 

[mikem]

Modern ropes that are left in the sun don't tend to:

I took a piece of rope used as a sling off a cliff facing directly into the sun in Sicily placed 28 years earlier on the FA. It was completely white (inside the knot it was original orange) and you could rub the sheath off with your fingers. On the tester tied as a loop it failed at 1860kg.
The 1" tubular tape from the same route (it was littered with junk) wasn't strong enough to hold the strain guage which weighs 5kg

https://www.mountainproject.com/forum/topic/116742325/damage-to-rope-from-sun

https://rockclimbing.com/forum/Climbing_Information_C2/The_Lab_F69/What_does_UV_radiation_do_to_rope_P2541570/

https://rockclimbing.com/forum/Climbing_Information_C2/Gear_Heads_F40/the_effects_of_age_and_UV_radiation_on_climbing_ropes_P64589/

Most of the problems in caves / mines are due to the chemicals dissolved in the water. However, more fixed ropes snap in the US due to rodents chewing them in the darker recesses...

 

[Cantclimbtom]

Although not answering your question, be aware that there is overlap with this and others' anecdotal testing on "The Internet" such as

https://www.youtube.com/watch?v=wynF9Yvx4ng

https://www.youtube.com/watch?v=KGB-natWgys

etc

 

[SamT]

Thanks guys.. plenty to go on there.

 

[mikem]

Cantclimbtom's links repeated, so you can see what they are:

(Those are zeppelin knots; rope left underground for 40 years is half as strong & "soft shackles")

Another possible factor is that wet climbing ropes are only 30% strength of dry ones (dry coatings improved this to 50 & 80% depending on the treatment), not sure if this is also true of semi-static, to same extent, as it's only the dynamic quality that is tested:

 

[mikem]

2019 drop testing old semi-static (last spent c.20 years outdoors - no problem, except trying to bend it!):

 

[mikem]

The rope was, however, on a rope course, so minimal contact with dirt - I imagine on most cliffs (& definitely underground) grit & mud being washed into the material makes more of a difference...

 

[Eds]

It is the core that gets the bulk of the damage and protects the sheath BUT it is the sheath that your ascenders or descender grip onto. So, a degraded sheath on a rope sling isn't too bad compared to ascending or descending a rope with a degraded sheath.

 

[Badlad]

Does anyone remember the rope that went up Victoria Aven in Peak Cavern. The bottom section of it lay on the mud bank just by the Mucky Ducks exposed to flood water. The rope had been in there a long time and had originated as a retired DCRO rope. About 20 years old if i remember correctly. There was a lot of concerns about using it at the time. I took a sample from the bottom section to Lyon and tested it. I forget the exact figure but it broke at about 1800kg on a pull test. It was a 3000kg rope when new so considering the knots used in the pull test would have reduced the strength by around 30% it showed a very reasonable loss of strength over the years in situ in all that mud.

Following that test I took a newer but used rope access 11mm rope up the aven to replace it. On close inspection as i ascended the 80m aven I realised that the insitu rope was in better condition that the one I was going to replace it with. Taking into account the test results of the bottom section I decided to leave it in and took my replacement out again. I used it several times after that to climb into various seldom visited leads at the top. Ropes are generally speaking stronger than you think.

 

[mikem]

Yes, the bigger danger in those situations is that the end of the rope is being washed around in the water & wearing against the rock further up!

A loop will also be twice (approx.) as strong as a single strand. Has any pull testing of wet ropes been done in the past?

 

[Bob Mehew]

For what it is worth, some while ago I tested a piece of 11mm SRT rope removed from Avalanche Pot in Gapping Gill along with a similar aged rope with limited use. The history of the Avalanche Pot rope is a bit unclear but I am confident it spent some 6 or 7 years in use as a club rope, followed by some 17 years in the aven followed by 4 years in storage before being tested. The Avalanche Pot rope survived on average just under 2 drops whilst the limited use rope survived over 4 drops. Brand new, I would expect the rope to have survived well in excess of 20 drops.

I had one rope sample placed as a hand line whose end was located just above water level. The sheath was rubbed through after one flood which caught the rope end and vigorously rubbed it on a rock higher up. On the same theme, you may not recall a sample I was given from Bitch Pitch which was cored within 12 uses, see Descent 221, August 2011 p28-9.

Most of my testing was done with wet ropes (soaked for 2 plus hours) and yes they are weaker than dry ropes.

 

[Ian P]

Some more information from the ever informative “How not 2” house

Do WET climbing ropes break weaker???

The rumor is that wet ropes are significantly weaker. The instructions that come with the rope say that it is dangerous. Climbing magazine advises not to use a wet rope. UIAA supposedly got 3 falls instead of 7 like normal, before it broke. What are we supposed to think and do when we end up...

www.hownot2.com

 

[mikem]

Hmm, not sure we can draw many conclusions from that (How Not 2): the dummy only weighed 6 stone with 15ft drop & most of the loadings only increased slightly with each test - suggesting that it was just knots being tighter the second time. Mammut used 12.6 stone & 15 metres...

 

[mikem]

Actually, Bob has pointed out that both drop tests were done over the same distance, just with different masses (16m seems to be the height of the rig)

 

[mikem]

Have just thought of a possible explanation - is the load absorbed into the rope in two dimensions or three? Can't find any testing using different weights over same range of drops, but the rope stretches vertically & compresses horizontally (in 2d), so is peak load proportional to the mass, or √ of, or ? It probably isn't any of these, as smaller mass means less dynamism is required of rope...