Care of harness, slings and rope
- Thread starter JB
- Start date
Bob Mehew
Well-known member
Dep said:
Re mass, it is 100 kg at the moment. Some research a year or so ago suggested the mass should go up since working people are carrying more gear these days (as well as being larger).
I can test the cows tails for you with the BCA Rope Test Rig, though before any one else asks, I am way behind on testing a load of samples from Hidden Earth 06. Look at http://british-caving.org.uk/?page=87 for details. Several clubs have set up simple test rigs, Craven and Wessex come to mind. Bradford is home to a deluxe version under Dave Elliot's care.
C
cucc Paul
Guest
Begs the question how many tackle sacks can you hang off your harness safely while doing SRT and where is the point at which you should start hauling them up seperatly. Trip to Rhinos a few months back when it was tripple rigged I ended up carrying one sack for bits (metal work mainly) and hauling an additional 6 (mainly full of wet rope). If that was all on my harness it must have been near 150/160kg I would have thought well above the test limits.
M
MSD
Guest
I change my harness/cowstails/safety fairly regularly. Not all at the same time, but whenever something looks worn or feels a bit old. I don't religiously change things at fixed intervals, party because the amount of caving I do is quite variable from year to year.
It's very rare for a harness to break. Either it must have been very worn, or something unlucky happened when he fell.
Mark
It's very rare for a harness to break. Either it must have been very worn, or something unlucky happened when he fell.
Mark
M
MSD
Guest
Fall factors.....
A fall factor is defined as the height of a fall divided by the length of rope you fall on to.
However, a definition is not necessarily an explanation. Try this for size:
When you fall, you gain speed, i.e. you gain energy. If you fall onto a rope, the idea is that the rope will stop you, i.e. you lose that energy again. The energy must go somewhere and it goes into stretching the rope. The capacity for a piece of rope to absorb that energy is proportional to its length. This means that a small fall (small energy) onto a long rope (lots of capcity to absorb energy) is OK, but a big fall (lots of energy) onto a short rope (little capacity to absorb energy) is bad news.
It may not be entirely obvious why a long rope can absorb more energy than a short one. It has to do with the fact that a piece of rope will get X% longer when you subject it to a force (it doesn't matter what X is). That's known as Hooke's law. So the change in length of a long rope will be much more than a short rope for a given force. The energy absorbed by a system is equal to force x distance (that's easy to understand, pushing a car 10 meters is ok, but pushing it a kilometer would be absolutely knackering, as would be pushing a 44 ton truck 10m). So if the distance is much more, you can absorb a lot more energy.
This is all very simplified and before anybody complains I know that perfectly well. I could set it all down in equations but I don't think that would help much. Since rope doesn't even obey Hookes law exactly, "correct" equations would be extremely complicated and of no use to anybody.
Mark
A fall factor is defined as the height of a fall divided by the length of rope you fall on to.
However, a definition is not necessarily an explanation. Try this for size:
When you fall, you gain speed, i.e. you gain energy. If you fall onto a rope, the idea is that the rope will stop you, i.e. you lose that energy again. The energy must go somewhere and it goes into stretching the rope. The capacity for a piece of rope to absorb that energy is proportional to its length. This means that a small fall (small energy) onto a long rope (lots of capcity to absorb energy) is OK, but a big fall (lots of energy) onto a short rope (little capacity to absorb energy) is bad news.
It may not be entirely obvious why a long rope can absorb more energy than a short one. It has to do with the fact that a piece of rope will get X% longer when you subject it to a force (it doesn't matter what X is). That's known as Hooke's law. So the change in length of a long rope will be much more than a short rope for a given force. The energy absorbed by a system is equal to force x distance (that's easy to understand, pushing a car 10 meters is ok, but pushing it a kilometer would be absolutely knackering, as would be pushing a 44 ton truck 10m). So if the distance is much more, you can absorb a lot more energy.
This is all very simplified and before anybody complains I know that perfectly well. I could set it all down in equations but I don't think that would help much. Since rope doesn't even obey Hookes law exactly, "correct" equations would be extremely complicated and of no use to anybody.
Mark
V
Vance
Guest
Dep said:
I disagree with this as we quite often expose ourselves to greater than FF1, and this is considered correct rigging. Excluding the obvious example of lead climbing up a shaft, the most common example (IMHO) of being exposed to greater than FF1 is on traverse lines where you have to go higher than them to proceed. I know that the traverse line will take some of the energy from the fall but it's easily possible on a horizontal line to fall twice the length of your cow's tail, an FF2 fall. That's why we use dynamic rope on our cow's tails (and should use it to attach to your upper ascender if you regularly use it to provide you with safety while you run around.) Of course, in an ideal world all traverse lines would be at head height and we'd never have to go above them.
But that leads on to another situation where we expose ourselves to even greater fall factors. How many times have people seen traverse lines snaking off down slopes over pitch heads to an immediate rebelay? A perfect example of the former for me is the rock bridge in Alum Pot. A fall from there will see you snaking down a five metre slope to fall on a half metre cow's tale. Even taking into account the traverse line rope taking some of the energy (which wouldn't be a lot as you'll only stop when you hit an anchor point placing most of the load on your cow's tale) that's a hefty fall factor.
Space Doubt Caver
Active member
How long do you soak a new 10.5mm rope before using it?
cap n chris
Well-known member
You do not need to soak modern ropes prior to use.
cavingbiker
Active member
The BPC hasn't had a test rig for a few years, it was returned when the club replaced the building where it was housed.
What's changed exactly?
Pete K
Well-known member
This has been covered on a very recent thread on here. Also, this thread is from 2007!
In short, it's no bad thing to soak ropes and might still be a good idea to get the last of the white lubricant off before use in a wet cave, but the user instructions don't ask you to do it for any of the types of ropes I have purchased recently for caving or work at height.
In short, it's no bad thing to soak ropes and might still be a good idea to get the last of the white lubricant off before use in a wet cave, but the user instructions don't ask you to do it for any of the types of ropes I have purchased recently for caving or work at height.
cap n chris
Well-known member
Improvements.
Space Doubt Caver
Active member
I've always soaked ropes over the years because back in the day it was always considered good practice, but I never put any thought into why we do it, I remember someone saying "It is so the rope doesn't shrink while caving" but I'm not 100% sure of why, I soak new ropes because it's a thing I've always been advised to do.
I didn't know there was any lubricant on the rope, but that does explain the water going a creamy colour.
Cantclimbtom
Well-known member
I double up or quadruple up the rope (depending on length), chain the rope (aka "daisy chain" or "chain sinnet") and put in a washing machine with no detergent, on cold quick wash, when Mrs cantclimbtom is not around. The last factor is essential for the safety of the rope user 
Edit, not sure of accuracy, but the traditional wisdom of soak all ropes, seems to be changed to [only] soak semi static ropes. No idea of the truth to that but that's what I do...
Edit2, maybe the lubricant is good for dynamic properties but unhelpful when you want it static?
Edit, not sure of accuracy, but the traditional wisdom of soak all ropes, seems to be changed to [only] soak semi static ropes. No idea of the truth to that but that's what I do...
Edit2, maybe the lubricant is good for dynamic properties but unhelpful when you want it static?
Last edited:
Space Doubt Caver
Active member
put in a washing machine with no detergent, on cold quick wash, when Mrs cantclimbtom is not around. The last factor is essential for the safety of the rope user
Many years ago when I was first getting into SRT we kept noticing that ropes that 'should' be perfectly adequate for a given pitch weren't, which was quite puzzling (and sometimes very annoying). One day I took a new rope to Long Kin East but we changed our minds about what we were going to do and left this particular rope at the entrance to the pot, where it got very wet while nicely hanked up. Anyway, we later hung up this rope as it was to dry out, and when it was dry we noticed that the hank was very tightly wound – in fact we had the devil of a job undoing the rope, as it was so tight. When we had managed to do so, we measured it and found that it had shrunk by quite a lot – as I say, this was a long time ago, so I can't remember the details, but it must have shrunk by somewhere between 5 and 10% to have such an effect on the coil's tightness.
So we started to pre-soak and thereby shrink every new rope.
Still not sure what's changed with the ropes themselves, even with capnchris' oh so helpful reply. Seems the user instructions have changed though.
I prepared 200m of Courses Courant Equirial (however you spell it) about 10 years ago. Plenty of white lubricant came out in the soak and there was 10% shrinkage. I prepared 200m of Petzl club recently, with negligible shrinkage so that may have changed, unless it's rope specific. But judging by the colour of the water during soaking, the most lubricant I've experienced with any rope, came out of it! Not sure if I've ever abseiled on a new rope that hadn't been pre-soaked to remove the lubricant so not sure how much difference it makes.
Another question would be what, if any, affect the lubricant may have on aquatic life in caves, if it hasn't been removed by pre-soaking?
So even if ropes don't generally shrink anymore(?), if the lubricant affects abseiling control and/or it's not good for cave life, then pre-soaking still sounds like a good idea, even if the manufacturers' instructions make no mention of it.
Space Doubt Caver
Active member
That is a very good point,
