Cow tails options - What do you do?

[Tommy]

I am wondering what other people use for their cows tails and why?

Since starting a couple of years ago I have used a piece of 10mm dynamic rope with a fig 8 ~2/3rds of the way down and two screwgates in captive barrel knots at the ends, creating a short and long, the fig 8 goes straight on to my central mallion.

This appears to be the most common method with those I cave with, with some having the slight variation of a longer 'long' shortened with an alpine/overhand partway down, clipped into the end crab, giving a super long, long and short. If that makes any sense.

I've seen someone use a quickdraw dogbone as a short, and a mate in the pub informed us all enthusiastically that he's bought a Petzl Connect Adjust - nifty looking bit of kit, although I haven't read into the specs and testing for fall performance etc.

Any ideas and discussion much appreciated. For what it's worth my own caving has not been limited by the basic setup, but I always like to know what's out there.

 

[Simon Wilson]

Cows tails again? It must be a wind up.

This should end all discussion on the subject.

Link for translation of French report on cows tails is http://british-caving.org.uk/wiki3/lib/exe/fetch.php?media=rope_testing:lanyard_tests_v6.pdf, thanks to Damian for doing it.

The French report ends with this:-
"From the point of view of shock absorption, Cow's Tails made from dynamic rope and knots at both ends achieve the best results. The effect of the diameter and of the weave of the rope on this shock load is not significant. Furthermore, the results are similar for knots that are well tied and knots that are badly tied, that is when the ropes cross over each other, and also whether they have been pre-tightened or not. This method also allows the lengths of the Cow's Tails to be adapted to the size of the user. Figures of Eight Knots, Overhand Knots or Clove Hitches can be used at the harness end. At the other end, a Figure of Eight Knot or an Overhand Knot and also a Barrel Knot can be connected to the karabiner. The Barrel Knot is being increasingly used by cavers and has the advantage of holding the karabiner in place. It is, in effect, completely secure and furthermore is the knot that provides the best results in both the static and dynamic tests."

So you can use any climbing rope and tie it with any of the usual knots and it'll be about as good as you can get but the majority seem to use an overhand and two barrel knots.

 

[JasonC]

After seeing it suggested somewhere here, I tried having two overhand knots in the middle, both attached to the central maillon, forming a short loop.  Into this is clipped a third crab, making a super-short cowstail.
Cons: it makes the maillon more cluttered
Pros: Occasionally, say on a slack traverse line, clipping this on gives an enhanced feeling of security
I quite like it but I wouldn't argue it's significantly better than the standard set-up.

 

[Mark Wright]

The so called Barrel Knot is in fact a Scaffold Knot. A Barrel Knot is used for joining ropes together and is a very different knot altogether. 

The Scaffold knot can be tied with either a double twist (most common) or a triple twist. Testing carried out by Lyon Equipment on behalf of the HSE back in 2001 confirmed the double twisted version to be the best energy absorbing knot when compared with a Fig. 8 or 9.

The triple twisted version (not tested by Lyon Equipment in 2001) offers even more energy absorption. I use a double twisted Scaffold Knot on the end of my long cow's tail and the triple twisted version on the end of my short cow's tail. The short cow's tail generally has more load applied than the long one as this is what you would normally use for passing re-belays and is easier to untie after loading. I use an overhand knot in the middle as this is a better energy absorber than e.g. a Fig. 8, and uses less rope.

The Scaffold Knot gets its name from when it was used to attach a hangman's noose to a hangman's scaffold, which is where modern scaffolding gets its name. The end of the noose rope is thrown over the hangman's scaffold, tied, and then snugged up on the scaffold. The noose is then tied in the other end with different numbers of twists depending on whether it was a man or a woman being hanged.

The method described by JasonC is commonly used in industry but, as he mentions, it is a bit of a clutter on the ventral attachment point on the harness.

Shaun Puckering showed me an interesting way of shortening the long cow's tail. The cow's tails are rigged as described above but with the addition of a short length of 6mm accessory cord tied with a Prussik knot around the rope and attached to the ventral attachment point on the harness. This allows unlimited adjustment of the length of the long cow's tail for different applications.

I use a Petzl Connect Adjust for aid climbing and it is brilliant, though a little on the expensive side for general caving use.

Mark

 

[Simon Wilson]

http://www.irata.org/safety_notices/Safety%20Bulletin%208%20%20Dangerous%20knot.pdf

 

[GT]

Ouch!

 

[Mark Wright]

All knots are potentially dangerous if incorrectly tied.

Mark

 

[Bob Mehew]

The barrel knot is claimed to have a significant advantage in that it grips the crab so keeping the crab in the correct orientation for clipping into what ever.  Fig 8, overhand or what ever other knots do not provide that grip.  Some people developed elastic band type devices to achieve it but then that had the downside that the band will hide dirt and retain moisture etc.

 

[Fulk]

My experience of these 'rubber bands' is that they don't hide dirt and retain moisture etc.

 

[Geoff R1]

ARRRRRR  Cowtails still being discussed after all these years (smile) !!!!!!
IMHO use a barrel knot and only a barrel knot to connect cowtail and krab.

Dirt or moisture is not the issue for me and never will be.
Much more important is the fact that a loose loop type of knot (e.g.  Fig 8 loop) AND a rubber retainer to hold the loop in place risks the cowtail and krab being attached to each other BY ONLY THIS THIN BIT OF RUBBER  ... if one part of the rope loop ever elongates through use and slips over the krabs gate.
Personally I for sure dont want to risk this (smile)

 

[Fulk]

Apologies if I'm being stupid, but I don't know what you mean by:

if one part of the rope loop ever elongates through use and slips over the krabs gate.

Would you mind explaining?

 

[SamT]

Apologies if I'm being stupid, but I don't know what you mean by:

if one part of the rope loop ever elongates through use and slips over the krabs gate.

Would you mind explaining?

I think its along the lines of this..

https://vimeo.com/29836772

It caused the fatality of an up and coming young climber .

http://www.climbing.com/news/the-quickdraws-that-led-to-tito-traversa-death/

 

[Geoff R1]

SamT yes, your UKC safety video shows a wrong 'set up' from the start (assembled wrong or comes out of rucksack wrong)  but the result is the same ...

If you have a long loop in the Fig 8 knot attaching the cowtail krab AND you use a rubber retainer, its all nicely attached ... and safe. 

Now just move one section of the Fig 8 loop thought the Krabs gate AND its apparently STILL ATTACHED  ... BUT the krab is held to the cowtail ONLY by the thin rubber retainer ... just as shown in your video. 

OK, perhaps when the Fig 8 loop was originally tied it was nice and small and with small risk of this happening, but as the cowtail is loaded during caving and the knots tighten further, the loop enlarges and the risk increases.  Then it takes just one 'event'

IIRC there was at least one reported caving accident due to this and one near situation of a light girl. 
Perhaps others have a better memory 

Hence why I use Barrel Knots   

 

[jonnyrocketboots]

So what if someone asks a question that has been asked before?
I've probably asked several on here that no doubt more experienced cavers have answered before.
And I've been grateful for their reply even tho they may be repeating themselves!
Coach and Encourage guys!

 

[andrewmcleod]

The triple twisted version (not tested by Lyon Equipment in 2001) offers even more energy absorption. I use a double twisted Scaffold Knot on the end of my long cow's tail and the triple twisted version on the end of my short cow's tail.

The triple offering more energy absorption is interesting but surely you want the most energy absorption on your long cowstail as this is where you can take the longest falls? I recognize that fall factors are important but I would much rather take a 50cm FF1 fall than a 1m FF1 fall. If you take a fall where the energy absorption in the knots saves you from injury it is probably time for a new cowstail.

 

[global_s]

So from this thread I've learnt that I should actually be calling barrel knots, scaffold knots.

If using independent cows tails is there any reason I shouldn't use a scaffold knot to connect it to the central mailion rather the a fig 8/overhand?

 

[damian]

If using independent cows tails is there any reason I shouldn't use a scaffold knot to connect it to the central mailion rather the a fig 8/overhand?

Be aware that, if you do, you might well find it hard to take the cowstails off the Central Maillon between trips ... if it's a steel maillon, left like this it's highly likely to rust. Alternatively, if they do come off, then you'll need to retie them each outing.

 

[global_s]

Be aware that, if you do, you might well find it hard to take the cowstails off the Central Maillon between trips ... if it's a steel maillon, left like this it's highly likely to rust. Alternatively, if they do come off, then you'll need to retie them each outing.

Thank you. I'll stick to a fig 8 then.

 

[Bob Mehew]

If using independent cows tails is there any reason I shouldn't use a scaffold knot to connect it to the central mailion rather the a fig 8/overhand?

In addition to Damion's comments, the knot is asymmetric so if you fall on one end you get a different response to falling on the other end.  I have not done any tests to see if there is a difference but my expectation is it will.

 

[Mark Wright]

The triple twisted version (not tested by Lyon Equipment in 2001) offers even more energy absorption. I use a double twisted Scaffold Knot on the end of my long cow's tail and the triple twisted version on the end of my short cow's tail.

The triple offering more energy absorption is interesting but surely you want the most energy absorption on your long cowstail as this is where you can take the longest falls? I recognize that fall factors are important but I would much rather take a 50cm FF1 fall than a 1m FF1 fall. If you take a fall where the energy absorption in the knots saves you from injury it is probably time for a new cowstail.

I'm comfortable with the energy absorbing capabilities of a double twisted scaffold knot, as I said, the main reason I use a triple twisted version is that they are easier to untie after loading and the short cow's tail is the only one you really ever hang on.

Mark