Amount of rope needed for Cowstails

[Subpopulus Hibernia]

Anyone got an idea of how much dynamic rope I'd need for a set of cows tails? I want to just go into the local outdoor shop and order a length and then not have to trim off the extra length with a knife heated on the hob. Cos I don't have a gas hob - but that's a different problem.

Or is this literally a 'how long is a piece of string' question?

 

[MJenkinson]

At a guess, 1m for your long, 0.5m for your short, 0.5m per knot - 2.5m????????????

 

[Fulk]

Well, I'm afraid it all depends ? how long do your want your safety-cords to be? I favour a very short, short cow's tail (almost as short as I can physically make it) on the ground that I like to be held in very close to the rebelay when passing one when descending; others say 'How can you cope with such a short cow's tail?' Yes, sure, it can sometimes cause problems on, say, a high traverse line, but I reckon you've got to compromise somewhere.

Then again, what sort of knots do you favour? I suspect that there's not much you can reliably do apart from buying a bit of over-length rope and finding some method of cutting it later (maybe go back to your local outdoor shop and use their rope-cutter?).

 

[Mattrees]

Or is this literally a 'how long is a piece of string' question?

Afraid so; my arms may be longer than yours, I make three turns in my fishermans, I may like my short shorter than yours, even different rope diameters will tie differently.

That said, I have just untied a set of cowstails and measured them at 2.6m. I think the tails are a little long so 2.5m sounds reasonable.

The solution suggested here looked good but I haven't used it myself: http://ukcaving.com/board/index.php?

 

[mikem]

Link takes me back to the home page...

Mike

 

[Mattrees]

So it does, sorry. Try this: http://ukcaving.com/board/index.php?topic=20674.0

 

[Pitlamp]

I'm tall; I like my long and short cows tails very long and very short respectively.
I take considerable care over tying the three knots such they they're as small a volume as possible (factoring in packability in minimal space). I'm assuming, like me, you're using a single piece of rope for both cows tails?

I've always found 2 metres of dynamic rope to be adequate, provided care is taken with knot tying.

But I'm just an ordinary potholer - ask someone who really knows rope, such as Mark Wright.

 

[pwhole]

I use exactly 3.5m, which gives me a short (about 30cm), a long (about 60cm), and a very short loop between them of about 15cm, with a snaplock krab on that for passing (most) rebelays. Overhand knots on the central maillion, and three-turn barrel knots on the krabs with a 5cm stub. The downside of this method is there are two knots on the maillon, but the upside is you have three cowstails instead of two, and the very short one is also very handy for traverses, Tyroleans, aid-climbing, etc. Also the three-turn barrel knots give you plenty of shock-absorbency if you're flinging yourself about a lot, as I tend to do. Just remember to work them open after every trip and rinse them out thoroughly.

 

[Mark Wright]

As many have already mentioned, it is a personal choice and depends on what you might be using them for. Cow's tails set-up for general caving might be very different to cow's tails set-up for aid climbing.

There is loads of information on the web about what the best cow's tail length might be but about a 2.5m total length to make a traditional long and a short should cover most scenarios.

Have a look at Al Warild's Vertical book;

http://www.cavediggers.com/vertical/1PERSON.pdf

Mark

 

[Disgusted from Cornwall.]

None, use tape.

 

[Rachel]

Well, I'm afraid it all depends ? how long do your want your safety-cords to be? I favour a very short, short cow's tail (almost as short as I can physically make it) on the ground that I like to be held in very close to the rebelay when passing one when descending; others say 'How can you cope with such a short cow's tail?' Yes, sure, it can sometimes cause problems on, say, a high traverse line, but I reckon you've got to compromise somewhere.

I had the same problem for years - wanting to be close to rebelays but being short enough for that to cause problems reaching traverse lines. I eventually solved it by tying a butterfly knot about 1/4 of the way along my long cowstail, so I have one long/short one and one medium one. In answer to the original question, my set up takes 2.5m of rope, but I imagine most people would need a bit more as nearly everyone seems to have longer arms than me.

 

[JasonC]

I eventually solved it by tying a butterfly knot about 1/4 of the way along my long cowstail, so I have one long/short one and one medium one.

I like that idea, Rachel!  Currently I have a set-up similar to pwhole's (long, short and tiny in the middle) but it is a bit crowded on the D-maillon.  Might try that next time I can be arsed playing with it

 

[Fulk]

Disgusted from Cornwall:

None, use tape.

Why?

 

[Mike Hopley]

You can always* shorten a cowstail by clipping your Croll to it. This is adjustable between "full length" and "ridiculously short".

Sometimes this makes awkward maneuvers easier, such as too-tight rebelays or tension traverses. It's also an easy way to position yourself just below the casualty in a mid-rope rescue.

So if you like a super-short cowstail for rebelays on the way down, one option would be to use your Croll to shorten it. Then on the way up, you have a longer cowstail, and also for traverses if desired. This might require rearranging your kit on the harness maillon so that the Croll and cowstails are next to each other (which could affect other maneuvers like changeovers). I have not tested this idea myself!

* Except when your Croll is already in use, obviously.

 

[aricooperdavis]

You can always* shorten a cowstail by clipping your Croll to it.

Is that really safe? You don't want to fall on a Croll as it can tear through the sheath of a rope, and that's the last thing you want to happen to your cowstail!

 

[Tommy]

You can always* shorten a cowstail by clipping your Croll to it.

Is that really safe? You don't want to fall on a Croll as it can tear through the sheath of a rope, and that's the last thing you want to happen to your cowstail!

I think it's one of those things Ari, yes it's not ideal and bombproof, but if you understand the risk and act accordingly, overall it may be a better solution than a silly long cowstail. Accordingly meaning never have any slack in the line, being hyper sure of your footing, make sure you rigged well, and so on.

I've heard of people doing the same with Shunts or Prussic loops to make an adjustable cowstail, this is safer as they are untoothed, I tried with a shunt but it was too bulky on my harness. 'KISS'. I have not personally seen fall test data for Shunts and Prussics, but it will be out there somewhere. I believe a Shunt will slip at ~4kN on static 10mm rope, although don't quote me on that. That means it might act as a shock absober, assuming it doesn't fail in some way.

The Alpine Butterfly method seems to be pretty good. :

Tommy

 

[Mike Hopley]

Is that really safe? You don't want to fall on a Croll as it can tear through the sheath of a rope, and that's the last thing you want to happen to your cowstail!

That's a good question. I would say it's no more dangerous than the many situations you might use an ascender for protection.

In the situations I might use it (rescue, tension traverses...), it's a non-issue. But if you kept it for the whole trip down, then it could increase the risk in some situations.

Say you have a badly rigged (or badly bolted) traverse, with too much slack or just too low down. So you could have a rather heavy fall (maybe more than factor one). In this case, falling onto an ascender could be bad.

So yes, I think you could make a good argument that it's not smart to keep your cowstail in the Croll the whole way down the cave, even if you find it convenient.

In the specific case of passing rebelays? If the rebelay fails, you're in essentially the same situation as you would be coming up: falling onto your Croll. And you would expect a low fall factor anyway, with the rope above absorbing the impact. So I think that's okay.

Still, perhaps the best option is to get used to passing rebelays with a "long" short cowstail, rather than a super-short one. Personally, I don't "get" why a very short cowstail is that useful here. You still have to stand up (almost) the same amount to free your cowstail, regardless of its length. Maybe someone could explain it to me?

 

[Badlad]

I did some tests on using a chest ascender to shorten a cowstail once.  The situation I replicated was on a bolted aid climb where the person might stand up and allow slack into the cowstail with the croll attached.  As if slipping out of etriers or off a ledge for example.  The tests were 80kg dummy, Fall Factor one, onto 300mm of cowstail, ie a 600mm fall.

The results of the first drop was to make a small chink in the sheath.  However, the cowstail knots were hand tight and much of the force would have been absorbed by the knots.  A second test onto the now very tight knots ripped the sheath most of the way around the core.

Many cavers have over-tight cowstail knots so this sort of damage is possible.  The general advice is to retie cowstails occasionally to prevent over-tightening and also not to get into a situation where a dynamic fall is possible onto an toothed ascender.  The test shows that even a short fall can do damage and if other parts of the system are poorly rigged or maintained who knows what could happen, however lets face it, it would have to be extreme to kill you.

 

[Mike Hopley]

A second test onto the now very tight knots ripped the sheath most of the way around the core.

It's worth noting that the previous FF1 will result in much tighter knots than could ever occur as a result of normal caving.

After a significant fall, cowstails should not be retied but replaced. You could try retying them purely for getting out the cave (then they go in the bin), but this will be difficult (perhaps impossible).

An alternative could be to use the end of a caving rope to make new emergency cowstails. It's not as good as climbing rope, but still probably better than your FF1-tightened cowstail.

...and also not to get into a situation where a dynamic fall is possible onto an toothed ascender.

Yes; on reflection, this means it's probably a bad idea to keep your cowstail clipped into your Croll constantly on the way down. I still see no problem using it situationally, such as at a rebelay.

For bolt climbing, one might be even better off with cowstails that incorporate an energy absorber.

 

[aricooperdavis]

I think it's one of those things Ari, yes it's not ideal and bombproof, but if you understand the risk and act accordingly, overall it may be a better solution than a silly long cowstail. Accordingly meaning never have any slack in the line, being hyper sure of your footing, make sure you rigged well, and so on.

That makes sense, and as posters below you say it would be more of a one-off use than a habit that you get into a lot. I'm not sure that I would use the option to influence my cows-tails lengths though, since I would ideally avoid the risk of falling on my Croll. Handy to know about these things though just in case you need it; thanks.