Making cowstails.. Rope age question

[pwhole]

Thanks for the info guys. I'll buy some new rope. Just seems a shame to have a nearly immaculate rope going to waste. Ah well.

You could spend an afternoon with Lily Ardor (what a wonderful name). It might not be as soft and gentle as hers, but might make a good changing 'rug'

[Mike Hopley]

Even 'heavy loadings' will take up the 'slack' in the knots and increase the peak force seen by your body.

Sure, but by how much?

You could make the same argument about anything. Even a single use of a rope will make it weaker, therefore replace all your ropes after every trip. Also replace your harness.

My cowstails are pretty tight even when new, because I want secure knots, and I don't want them to change length more than needed. Relaxing the knots could easily take 10 -- 30 minutes even with a spanner.

I've never met anyone who actually does this, and I think it's unnecessary perfectionism. Focus on things that make a relevant difference.

[Kenilworth]

Obviously you're insane. Your safety connectors are your principal life saving PPE. Price for your life?

Not picking on Chris specifically since several people have made a similar comment, and since it always gets made every time these topics come up, but this is a bad argument. The money cost has nothing to do with anything. Is the cost of shiny new cowstails the appropriate money value of a life? 

I personally like to use things that will work, if I have them, rather than get more things. If a piece of safety equipment is safe enough, it does not need to be safer. We could increase potential safety factors (and cost) indefinitely with zero practical improvement.

There should be data available to answer the original question. I have read a lot of pull and drop test data on ropes and knots of various types and ages. Anymore I perform my own testing if I'm in doubt, which was interesting in the case of my hand sewn harness made from old van seat belts, or the emergency harness idea utilizing a cord through the crotch of some blue jeans.

[benshannon]

Exactly, it wasn't a "I don't want to spend money" question. More, that I have a rope that I don't use anymore because my climbing partner moved away and now I am bouldering almost exclusively and thought I could repurpose the rope for cows tails as I assumed they would take less force than a fall. I didn't realise this thread would incite such emotions in some people

[cavemanmike]

you should'nt be falling on your cowstails anyway so an old(ish) climbing rope would be ok in my eyes.

[mikem]

The problem is that there isn't any empirical data, because so many factors are involved. Bob's chart is as near as you can get to an answer, but as Mike Hopley suggests, secure knots is more important than badly tied ones "coz you relaxed them a bit too much"...

[Bob Mehew]

... secure knots is more important than badly tied ones "coz you relaxed them a bit too much"...

Again this is slightly misrepresenting what I mean by relaxing a knot.  In the two sets of 3 0.1FF drops shown, the samples extended by 3 and 5cm which came out of the knots.  In the five sets of 3 FF1.0 drops it was 16cm, that is the cows tail lengthened from 37cm to 53cm!  I predict more will come out if I had kept going as it is only when the peak forces are up around 10kN does the overall sample length stop extending.  (Sorry I am not in a position to do that test as yet.)  To spell out the point I am trying to make:

after a trip, unpick the knot so that you can move each part of the rope within the knot with respect to the bit next to it and then retension it as normal. 

There is no need to completely untie the knot and I am not suggesting you leave the knot not tensioned.  I am also assuming you have enough of a tail on the knot so it won't pull out because of a drop.

What I am asking you to do is to return each knot to the same condition it was before you went caving.  It is that simple.  That way you better protect your back.

[Chocolate fireguard]

It does seem a shame to throw the rope away, but I assume you are only thinking about getting one set of cowstails from it and dumping the rest?
If it was my rope and I was as confident of its past history as you are then I would use it for cowstails.

I remember seeing some of my old 9mm semi static pitch rope, with perhaps 10 years hard use and another 5 years in a bag in the cellar, drop tested (probably FF1 80kg) and surviving at least 1 drop.
So you could cut the rest of your rope into 10 or 15m lengths for use on those short pitches or handline climbs that sometimes use up and waste longer ropes, and where the extra bounce isn't excessive.

Or you could compromise, buy new cowstails and use the whole rope for that.

[Cripplecreeker]

I’m not sure that empirical data is really required. In the millions of hours that have now been spent by users of rope cows tails (for caving and industry), is there any instances of people being injured because their cows tails had lost/reduced their shock absorbing capacity? Not that I know of. In the very long list of things that can kill/injure you caving, this has got to be pretty much at the bottom. It’s good practice to undo the knots in your cowstails occasionally to check for damage though.

To me, the key questions are: was the rope in a fit condition to be used for cows tails before it went into storage? And, was it stored well (not too hot, no possibility of chemical contamination). If the answer to both is yes, then why not?

Ropes deteriorate through use rather than age:

https://www.theuiaa.org/documents/safety/About_Ageing_of_Climbing_Ropes.pdf

[mikem]

The empirical data is mainly required to cut down the online arguments that benshannon was commenting on!

Very few people have actually experienced a proper fall onto cowstails, as we do our best to avoid it.

[Cripplecreeker]

  I’m not sure anything will cut down the number of arguments on UK caving. Who would have thought the number of entrances to a cave in South Wales could cause so many posts.

[caving_fox]

It does seem a shame to throw the rope away, but I assume you are only thinking about getting one set of cowstails from it and dumping the rest?
If it was my rope and I was as confident of its past history as you are then I would use it for cowstails.

I remember seeing some of my old 9mm semi static pitch rope, with perhaps 10 years hard use and another 5 years in a bag in the cellar, drop tested (probably FF1 80kg) and surviving at least 1 drop.
So you could cut the rest of your rope into 10 or 15m lengths for use on those short pitches or handline climbs that sometimes use up and waste longer ropes, and where the extra bounce isn't excessive.

Or you could compromise, buy new cowstails and use the whole rope for that.

I've often seen this sort of advice and I've never really understood it. My old rope feels dangerous, so I'll make it shorter and then it'll be fine because a 10m pitch doesn't feel as bad. If there's even the slightest chance that a rope would fail on a 30m pitch, then it's the same chance on a 10m pitch? And I don't want to fall 'even' 5m!

Handline is perhaps a different use case but even there the rope will be supporting my whole bodyweight.

[mikem]

Modern ropes don't just break. It's a climbing rope, which may have lost some of its elasticity, so no longer as good to take a lead fall on (which is also what cowstails have to deal with) - it will still stretch on long pitches, which is annoying when prussiking, but less noticeable over short distances. Even if your anchor fails there is no way you will create a factor 2 fall on standard SRT, whereas it is possible to get more than that on a cowstail.

[Ian Ball]

If you're total bodyweight is on a handline you must be dangling no?

To be honest I really think that age is not a barrier to rope strength.  It is made of nylon which is hardy stuff.  Ropes used to be 3 years use, then 5 years use, now 5 years storage and 10 years use, ever increasing safety as datasets are compiled giving a greater proof of longevity?  A brand new never used rope left in the sun will scare me more than an old rope I'd looked after.  An old rope someone else had looked after for my cowstails I wouldn't be keen on.

With regard to using old rope for a short pitch.  My personal view is that it 'feels' less risky but also that cutting an old rope down is more to remove damage sections and the ends where the majority of the knotting happens rather than saying a short pitch is less dangerous than a long one.

[mikem]

If you're on one marginal foothold, then the majority of your weight can be (whilst you're stepping the other foot up) - it still ain't gonna break under these sorts of forces!

Age just means the cumulative effects of UV etc are likely to be greater.

& the short lengths was more about reducing the bounce, because it's a dynamic rope.

[andrewmc]

If the exact details of forces on cowstails with tight knots/loose knots/rope diameter etc. were that critical, then rather than arguing about small differences we should just be using shock-absorbing lanyards.

But we don't, because we don't need to, and it's a faff.

[mikem]

Bob's chart on previous page shows that for factor 1 & 1.25 falls on both short or long cowstails, the third drop hits about 1.5 times the peak force of the first drop, so it is significant, but we don't know how much of that is due to tightening of the knots & how much to damage of the internal structure of the rope. Fortunately it's very rare to actually subject a cowstail to a "clean" drop in use.