Spelegyca - yay or nay?

[damo8604]

Been looking at getting some Spelegyca cowstails, whats the general consensus on using these as cowstails? Petzl website states that these are 'useful for passing re-belays whilst caving' but are they fit for purpose?

 

[Pete K]

IMO Nay.

1. Can't adjust the lengths so they won't be as efficient as they could be.

2. Cost vs. dynamic rope.

3. Yes they have the proper EN mark but they still impart a significantly higher impact force to your body than equivalent dynamic cowstails with tightening knots.

Again, IMO.

 

[Antwan]

What Pete says

 

[Fulk]

Have a look at the NSS Cavechat.org (The US version of this).

 

[Bottlebank]

Have a look at the BCA's test results. To save time, I think they came bottom of the list.

 

[Alkapton]

Real cavers make their own.

That's because they know how to tie and untie knots.

If you cannot untie - or at least slacken - the knots in your cowstails THROW THEM AWAY.

 

[Fulk]

If you cannot untie - or at least slacken - the knots in your cowstails THROW THEM AWAY.

Why?

 

[Pete K]

Because the largest part of a set of cowtails' ability to absorb shock is down to the knots tightening as the fall is held, the 50/60cm of dynamic rope does little in comparison.
Crack off your barrel knots after each trip or if they're really stubborn, wiggle the krab out and the knot will come apart. Permanent knots in ropes will weaken the rope, even if untied eventually. If the rope still holds dents and kinks when unknotted, chuck it and get a new set.

 

[cap n chris]

Nay. Many reasons. All been covered elsewhere in lots of other threads.

 

[Fulk]

Permanent knots in ropes will weaken the rope

By how much? It seems to be accepted that simply thing a knot in a rope reduces its putative strength by ~30%, so by how much extra does leaving a permanent knot weaken it? Suppose it's another 10% . . . . well, the residual strength of a knot that would break under a load of, say, 25 kN would be ~15 kN . . . . more than adequate for the average caver, I'd say. Even if the strength is reduced to a mere 50% . . . well, that strikes me as being adequate.

Also, I seem to remember reading a remark by Bob Mehew (??) somewhere or other that in-situ ropes are best left with knots permanently tied.

 

[Alkapton]

I don't know the details - I don't need to.  Cowstails are short.  Shorter the rope the more shock has to be taken by the knot.    In a fall factor 1 fall on cowstails (easy to do if you slip at pitch head etc.) very very little force is taken by the standing part of the cows tail, the cavers body and harness will no doubt take most of the shock, but the knots take a lot, if the knots are loose they can take much more of the shock.    If you fall on the rope you are climbing it will be much longer so able to absorb more shock (but also there will be more shock to absob)

I owe my life to a cowstail, many many others do also.

Their condition is more important than the condition of the rope you are climbing on - they get much more abuse - eg in crawls, getting snagged on sticky out bits of cave, grit and abrasive stuff WILL build up in the knots.

I always kept mine so loose that in wet cave the knots are nearly undoing themselves.  I always check the knots are dressed neatly at pitch heads.  If they are dressed neatly they will have maximum shock absorption.

 

[cap n chris]

If you are in the habit of falling onto your cowstails then you definitely do NOT want to own a spelegyca. As this thread appears to be going off at a significant tangent maybe it's worthwhile doing a poll to find out how many people have actually fallen onto cowstails. Me, never. Done a few trips too so would have thought it might have happened so far, if it's as common as people think it is.

 

[Ed W]

I understand the reasons behind the idea to slacken cowstails knots, but I do question the usefulness in practice.  If I recall correctly the advice to slacken the knots is relatively recent (last few years), is there any evidence that anyone has suffered a shock related injury when falling on a cowstail in a cave (short of being wilfully stupid like falling from above the traverse line so as to get a FF1+), where a slacker knot would have made the difference?  I would suggest that in most cases the cave should be rigged in such a way that FF1 should be difficult to achieve in the first place.

I would be far more worried about the possibility that the knot was insecure just when you needed it, which I would suggest would be a definite risk in the case where the knot is so slack it is constantly untying itself throughout the trip.  Equally how much slack is really left in the knots after half a dozen free hanging rebelays?  I seem to recall similar advice about 20 years ago to include shock absorbing knots into rebelay loops.  Eventually the received wisdom seemed to morph from "everyone should use them" through "they might help" through to "their effect is so unpredictable that they should not be used and the cave rigged in such a way that potential shock loads are minimised".

Perhaps I am just getting old and grumpy...

 

[Pete K]

Permanent knots in ropes will weaken the rope

By how much? It seems to be accepted that simply thing a knot in a rope reduces its putative strength by ~30%, so by how much extra does leaving a permanent knot weaken it? Suppose it's another 10% . . . . well, the residual strength of a knot that would break under a load of, say, 25 kN would be ~15 kN . . . . more than adequate for the average caver, I'd say. Even if the strength is reduced to a mere 50% . . . well, that strikes me as being adequate.

Also, I seem to remember reading a remark by Bob Mehew (??) somewhere or other that in-situ ropes are best left with knots permanently tied.

I agree that the safety margin in modern equipment is very good and allows these differences to occur between people's kit whilst remaining adequate. I also choose to factor in my own safety margin by using best possible practice and so far I'm still alive, I'm not a fan of adequate, especially as my advice goes to people who pay me for it as it is my job. I don't lose sleep by replacing my cowstails often or spending a few seconds loosening the knots off after a trip. No one is saying the tape type cowstails are not fit for purpose, they are tested to be so. I just believe that the rope ones are far better.
The advice re. Permanent knots is concerning the long term distortion of the fibres in the core. A knot left in a rope for a considerable time is okay. However, if you untie that knot sometime later and reuse the rope for another purpose, say that bit is now a straight section of an in situ pitch, that section will still remain deformed and will not share the load so well across the fibres and hence be a weak point in the rope. In that respect a permanent knot should be left in and not untied after a considerable time and reused.

 

[Fulk]

I'm with Ed W on this ? and no Ed, you aren't getting old and grumpy. I think (personal, subjective opinion) that there is an element of paranoia creeping in here. I started dabbling in SRT in the early 70s (1970s, that is  ), and for 40-odd ears I've used 'permanently-tied' cows-tails (albeit changed quite frequently), and I have no reason to change my approach.

 

[SamT]

is there any evidence that anyone has suffered a shock related injury when falling on a cowstail in a cave (short of being wilfully stupid like falling from above the traverse line so as to get a FF1+),

Only anecdotal - i.e. someone was stood on some scaffold working on a shaft top lid, cows tail round scaffold at feet, slipped, and put his back out quite badly.

where a slacker knot would have made the difference

who knows, but I bet given a choice, he'd have gone for a slightly slackened knot over a jammed up tight one.

 

[damo8604]

I have never fallen on my cowstails but it's the one bit of kit I change quite regularly, in fact I bought some more a couple of weeks ago.....

Loose knots  I understand the logic behind it but I don't think I would trust them at the top of a 40' pitch, I remember looking at my barrel knots last week thinking "maybe I should have bought a bit longer rope" as I was hanging off the side of the porch as there isn't much of a tail left!

I'll give the spelegyca a miss then, it's just I have an unhealthy compulsion to buy shiny things!

 

[Cave_Troll]

personally i'm more worried about having to remember to check every time i might load them that the loose knot is still actually tied.

 

[Pete K]

I have never fallen on my cowstails but it's the one bit of kit I change quite regularly, in fact I bought some more a couple of weeks ago.....

Loose knots  I understand the logic behind it but I don't think I would trust them at the top of a 40' pitch, I remember looking at my barrel knots last week thinking "maybe I should have bought a bit longer rope" as I was hanging off the side of the porch as there isn't much of a tail left!

I'll give the spelegyca a miss then, it's just I have an unhealthy compulsion to buy shiny things!

Loose in the context of my replies is entirely the wrong word, my apologies. What I mean is a knot that is tied and dressed correctly and that has been tightened by hand and has not had a body load applied to it. I've never had a well dressed knot with enough tail come undone. Hope that clarifies it for everyone.

 

[Cartwright26]

Ive used both these and dynamic rope, the beauty of them are they are easy to maintain and they stay the same length, these are a little short but work well, the issue i have and the reason i changed over is that the fall factor if i were to end up shock loading via a traverse etc as i cant imagine shock loading on a rebelay that this impact may have severe effects on my body as i cant imagine that even though the stiching is designed to unstitch to give some stretch this would compare to dynamic which has a more fluid action. Also having rope cowstail mean that you can undo it all and fully inspect the rope and krabs for damage. Hope this helps a little