Cowstails

[verticaver]

Wow, what a great thread. If anyone is interested in the idea of the sewn cowstails, I've found a similiar product available right here in the US sold by a canyoneering gear company, selling it under the Singing Rock name:

http://www.wildernessadventures.com/sto ... ductId=148



Plus, at $16.95, it's the cheapest sewn cowstails I've ever found, MUCH cheaper then the Beal version.

I understand many of you feel that having a knot reduces the peak impact force to the body better then a sewn termination and I'm not going to argue that point, it's just a personal choice I guess. I've done industrial rope access work for a few years and I've had a triple pair of the sewn Petzl Jane lanyards for a long time and they have worked great. It's slowly becoming a trend in industrial rope access to avoid knots whenever possible and move towards sewn terminations in recent years due to their superior strength and reliability, nearly achieving original strength of the rope instead of the loss which results from tying a knot.

There are so many other shock absorbing elements in the system that the actual "true"impact forces to the body should be tolerable even at or above 9kN. If I'm not mistaken, somewhere in Apline Caving Techniques, in the chapter on light rigging, they state that the human body can tolerate upto 12kN. The slight stretch in the rope, the tightening of the anchor knots, potential pendelum effects, splaying of the butt fat by the harness straps at the moment of impact, etc, these all factor into a reduction of those peak forces. I've read some discussion of rating cowstails for more then a factor 1 fall and I'm suprised because the implicit idea of how cowstails are designed to interface the caver to the rope system have always dictated that they never be exposed to forces over a factor 1. If you are putting yourself in a position to apply more then a fall factor of 1 to your gear then you are bound to have a problem somewhere, whether your cowstails break, your bolt breaks, or something else breaks. It'd simply be a matter of personal good conduct to avoid allowing yourself to be in a situation where your tails might take more then a factor 1 fall.

I mention this so that if some cavers want a pair of tails with a sewn connection, they can get one for even less then the Petzl Spelegyca. Singing Rock has been a reputable harness maker for a while now and they appear to have beefed this set up pretty well. I just ordered a pair and expect them within the next week or two.

Good thread folks, keep it coming!

[graveleye]

No way to adjust the length of that is there?

[Scott McCrea]

The Singing Rock Lanyard V comes in three different sizes. The 10/17 inch version would probably make better cows tails than the 10/30 inch version. They also make a 40/40 inch.

[hunter]

These look nice but it is worth noting that they appear to be static and that the instructions say "The middle loop is attached to the harness with carabiners and energy-absorbing device". To my mind this would be better with dynamic rope.

Hunter

[Carl Amundson]

Nice, but I will continue to make my own out of dynamic rope.
It is cheap and easy ( and I'm all about cheap and easy )

[verticaver]

The Singing Rock Lanyard V comes in three different sizes. The 10/17 inch version would probably make better cows tails than the 10/30 inch version. They also make a 40/40 inch.

Hey Scott,

I just recieved my 10/30 inch set and immediately compared them to my petzl tails. The short leg is about an inch shorter and the long leg is a couple inches longer. They are built pretty stout. I'm going to use them and I'll make another post after I've tested them in the field to let you all know how I like them compared to the Petzl tails.

To answer the other question, nope, no way to adjust them.

[fuzzy-hair-man]

I understand many of you feel that having a knot reduces the peak impact force to the body better then a sewn termination and I'm not going to argue that point, it's just a personal choice I guess. I've done industrial rope access work for a few years and I've had a triple pair of the sewn Petzl Jane lanyards for a long time and they have worked great. It's slowly becoming a trend in industrial rope access to avoid knots whenever possible and move towards sewn terminations in recent years due to their superior strength and reliability, nearly achieving original strength of the rope instead of the loss which results from tying a knot.

Why do you need that extra strength? they did static tests in that French cowstails report and the lowest scoring test is 8.01 for a previously shock loaded cowstail in 8mm rope! Cowstails are for dynamic loads/falls if one of your selection criteria is strength then IMO your'e applying the wrong selection criteria the only static pull a cowstail should see is your own body weight (or perhaps 2 people if you were doing a pickoff). I don't know how knotted cowstails are not reliable indeed the same report tests badly tied and badly positioned barrell knots as well as non preloaded barrell knots and finds there is no significant degradation in performance. I'd say the benefits in terms of cost, adjustability, and performance make knotted cowstails a clear winner against sewn cowstails. The only cons I can see is that knotted cowstails might not be as neat or look as pretty and use knots so they might be more prone to wear at the knots, the first is not really a practical issue as far as I'm concerned the second is more than offset by the fact that knotted cowstails are cheap and a length of dynamic rope is easy to find making them cheap and easy to replace regularly, which you should be doing knotted or not.

There are so many other shock absorbing elements in the system that the actual "true"impact forces to the body should be tolerable even at or above 9kN. If I'm not mistaken, somewhere in Alpine Caving Techniques, in the chapter on light rigging, they state that the human body can tolerate upto 12kN.

According the same report the european standard is 12kN, I'd say this is where Alpine Caving Techniques got it from. Incidently according to the same report the Petzl spelegyca gives ~15kN peak force off a fall factor 1 with both sides connected, that's dangerous!!! I think after you had absorbed a peak force of 12kN you wouldn't be in good shape and possibly need rescuing away. I'd much rather avoid that sort of fall.

The slight stretch in the rope, the tightening of the anchor knots, potential pendelum effects, splaying of the butt fat by the harness straps at the moment of impact, etc, these all factor into a reduction of those peak forces.

OK, so you arrive at a rebelay, the anchor is a bolt into the rock you clip into the carabiner, the only shock absorbing components I can see are your cowstails, your harness and you.

I've read some discussion of rating cowstails for more then a factor 1 fall and I'm suprised because the implicit idea of how cowstails are designed to interface the caver to the rope system have always dictated that they never be exposed to forces over a factor 1. If you are putting yourself in a position to apply more then a fall factor of 1 to your gear then you are bound to have a problem somewhere, whether your cowstails break, your bolt breaks, or something else breaks. It'd simply be a matter of personal good conduct to avoid allowing yourself to be in a situation where your tails might take more then a factor 1 fall.

You're right people shouldn't get into a situation where a fall factor 2 is easily possible, however it can happen and sometimes through no fault of the user (bad luck) so I'd rather have some cowstails which give me the best chance to survive a fall factor 2. If your cowstails generate higher peak loads as sewn cowstails do, you're more likely to pull that bolt or whatever else your connected to... the dynamic performance of your cowstails helps protect all the components in the system by reducing the peak loads.

In the end I guess I can't see any compelling reason to use sewn cowstails and I can see several good reasons not to use them, being safety, adjustability (which I feel effects safety, bad length cowstails being more likely to result in hang ups and other stuff ups*) and the last being cost.

*I adjust my cowstails to within an inch so you can't tell me that Singing Rocks 3 lengths of cowstails satisfy my needs, indeed cowstail lengths IMO should differ from person to person with their relative body lengths so the chances of a sewn cowstail having both cowstails length being the right seem very slim.

[Bill Putnam]

Those of you who are still fans of sewn cows tails and lanyards for caving really should read the report. It doesn't matter how we "feel" about knots versus sewn terminations or rope versus webbing. The data tell the story and prove the point.

Cowstail Test Report - English Version PDF

If you can't bear to read the explantion of the tests and the tables of results, here's the crux:

Conslusion

Cow's Tails currently on the market that are entirely manufactured, whether they be single or
double, symmetrical or non-symmetrical, are not appropriate for either caving or work on ropes. In
particular, Cow's Tails made from sewn tapes, in widespread use by cavers and rope workers, can
pose a real risk. The tests have, in effect, shown that a Fall Factor 1 shock load could exceed 15 kN
(test 6) when the recognised maximum for work equipment according to the European Standards is
set at 6 kN.

However, it is possible to use manufactured goods by linking them to the harness with a knot to
specifically perform a shock absorbing role and thereby serving to keep the shock load for a Fall
Factor 1 fall within acceptable bounds. Different manufacturers offer lengths of dynamic rope with
pre sewn ends. With a 150cm Cow’s Tail, it is therefore quite easy to make a pair of nonsymmetrical
Cow's Tail, which is ideal for both caving and rope work. It can be joined directly to the
harness tie-in point with a Figure of Eight Knot, an Overhand Knot or a Clove Hitch.

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 pretightened
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.

One of the lessons from this series of tests is that the theory behind Fall Factors inadequately
explains how shock loads are absorbed by Cow' Tails. In particular it is the knots that absorb the
greater part of the energy from a fall and in various identical set-ups, it has been demonstrated that
the shock loads are inversely proportional to the fall factors (see p. 3213). Despite this we should
continue to teach that cavers should not position themselves above their anchor point when using
Cow's tails; fortunately this is a situation which is quite easy to identify. The tests carried out in less
favourable conditions gave shock loads well in excess of those that can be sustained by the human
body. Tests also showed that heavily used Cow's tails can break on the first fall.

Finally it is regrettable that the most recent laws and particularly article R 233-13-20 of the Fair
Labour Standards Act (added by decree on 1st September 2004) are not based on shock loads and
the limit of 6 kN. It requires that “[…] the protection of workers must be assured by means of an
appropriate Fall Protection system which does not allow a free fall of more than one metre or
limiting in the same way the effects of a fall from a greater height.”; Yet these tests indicate that a
fall of less than one metre can create a shock load above 15 kN.

In fall protection, the emphasis is on reducing the shock load on the anchor and on your body, without adding so much stretch that you hit something before the fall is arrested. As noted above, tensile strength is almost irrelevant, as any cows tail made from appropriately sized modern caving or climbing rope or webbing will be at least as strong as your body, your harness, your carabiners, or your anchor, unless damaged or otherwised compromised, in which case you should not be using it. This is particularly important to understand when considering lanyards and cows tails, as the use of a short one with carabiners at the ends can, in the most severe case, result in fall factors greater than 2. If that does not make sense to you, see pages 5-7, and paticularly page 7.

[Bob Thrun]

The Association of Mountaineering Instructors has posted a sample coppy of their magazine. AMI News, online. This particular issue has a few tests of lanyards with different fall factors, starting page 18. The graphs are of amazing poor quality. All that is readable are the large numbers giving the peak force. The issue may be downloaded from: www.ami.org.uk/b_editor/client_resource ... une-08.pdf

Bob Thrun