Cow tails options - What do you do?

[pwhole]

I slipped on an over-ambitious traverse once, after climbing higher than I should have relative to the anchors, and dropped a good 80cm onto my long cowstail as I was unclipping the short one - it was a triple-twisted knot, and it didn't hurt as much as I expected, but that may have just been lucky. However, the knot was jammed seriously tight after that, and I couldn't loosen it all later, even after soaking, so I figured that was a good time to get some new ones. But now I religiously loosen the knots when I get home, and so far, it's working fine, and the rope is also less damaged than it used to be when I didn't do this - they may even last longer as a result.

 

[andrewmcleod]

I slipped on an over-ambitious traverse once, after climbing higher than I should have relative to the anchors, and dropped a good 80cm onto my long cowstail as I was unclipping the short one - it was a triple-twisted knot, and it didn't hurt as much as I expected, but that may have just been lucky. However, the knot was jammed seriously tight after that, and I couldn't loosen it all later, even after soaking, so I figured that was a good time to get some new ones. But now I religiously loosen the knots when I get home, and so far, it's working fine, and the rope is also less damaged than it used to be when I didn't do this - they may even last longer as a result.

Some energy will also have been absorbed in the traverse line (if you were clipped onto a traverse line, not into an anchor).

 

[caving_fox]

Don't do what I did on Saturday and hit yourself in the face with one. My tooth will never be the same.

 

[Tommy]

Thank you all for your replies, in particular Mark for your broader discussion and historic tidbits - much appreciated. Apologies for my lack of involvement in the thread I have been away clipping bolts in Costa Blanca (above ground, for my sins).

Mark, you suggest using a prussic loop from the central mallion to achieve a level of adjustability. Forgive me, I suspect I am visualising this setup incorrectly (see attachment), so do correct me if I am wrong about the following:

In a situation where the long cowstail is shortened by this method, if the caver were to fall, I visualise the load through the prussic loop posing the hazard of damaging the cowstail rope. Are prussics tolerant of hard, dynamic loads? I'd be interested in any literature you have on this. Again this relates to my lack of knowledge regarding falls onto the Connect Adjust.

Simon, scoffing at a technical question being asked, though it may be for the umpteenth time, certainly isn't an educational and supportive opening gambit, even if you did go on to redeem the credibility of your posts with some informative content. Thank you for the PDF showing an incorrectly tied scaffold (nee-barrel) knot; that's going to induce all kinds of paranoia.

 

[Simon Wilson]

You're right and I apologize. However, I have said before that there is far too much of an obsession with cowstails. There are far more problematical SRT safety issues to worry about - such as wear of ascenders. Spits? arghhhhh!!! Don't go near them if you can avoid it.

This forum has a good search facility.

 

[Simon Wilson]

If you're a climber retire a 9mm climbing rope early and you will have all the cows tails and deviation cords you will need for the rest of your caving career.

 

[Tommy]

If you're a climber retire a 9mm climbing rope early...

Personally I'd rather use my climbing ropes until the end of their working life and also spend ~?5 on a short length of 9mm than having to retire an ~?80 rope at say, 4 instead of 5 years of climbing use.

I'd rather not lose out on 1/5th of ?80 (?16), for the sake of a single years worth of safe usable life from 60 metres worth of cowstails, my cowstail 'burn rate' is significantly lower than what would be cost effective here. But I do appreciate the nod towards frugality.

Keep in mind the climbing rope will be already be fairly ragged from gritstone and sharp bubbly volcanic stuff, lowering off sport routes, abbing in the fells and so on before it's even seen the kind of mud and abuse caving would subject it to.

New rope = peace of mind.

 

[Simon Wilson]

OK but it makes superb deviation cords.

 

[Tommy]

OK but it makes superb deviation cords.

I prefer old shoelace and spaghetti myself

 

[Mark Wright]

Thank you all for your replies, in particular Mark for your broader discussion and historic tidbits - much appreciated. Apologies for my lack of involvement in the thread I have been away clipping bolts in Costa Blanca (above ground, for my sins).

Mark, you suggest using a prussic loop from the central mallion to achieve a level of adjustability. Forgive me, I suspect I am visualising this setup incorrectly (see attachment), so do correct me if I am wrong about the following:

In a situation where the long cowstail is shortened by this method, if the caver were to fall, I visualise the load through the prussic loop posing the hazard of damaging the cowstail rope. Are prussics tolerant of hard, dynamic loads? I'd be interested in any literature you have on this. Again this relates to my lack of knowledge regarding falls onto the Connect Adjust.

Tommy,

Your visualisation of how the cow's tail and prussik knot is set up is correct.

I don't have any literature on it but the company Troll used to rig tensioned lines up with prussik knots for mountain rescue purposes back in the 80's and early 90's. They used to slip at around 6kN. If you did take a fall onto it there is a possibility it would glaze the cow's tail rope but you would probably want to replace the cow's tail rope if you did take a significant fall. With correct use there shouldn't be any possibility of anything greater than a FF1 fall.

Mark

 

[Madness]

Does anyone use sothing like a Kong KISA on their cowstails?

If you did you'd need to form a 'Y' of rope, the arms of the 'Y' being the cowstails and the tail of the 'Y' going through the KISA.

What yould be the best knot for joining the rope to create this confirguration, a figure 8?

 

[JoshW]

I was under the impression on the Kong KISA that it attached straight to your D ring by a carabiner. with a straight rope going through to form both the long and short cowstails?

anyone with one correct me if i'm wrong though!

 

[PaulW]

Like Josh I understand it threads through from long to short cows tail.  With different threading patterns through it for 9 or 10mm rope

 

[Madness]

I was under the impression on the Kong KISA that it attached straight to your D ring by a carabiner. with a straight rope going through to form both the long and short cowstails?

anyone with one correct me if i'm wrong though!

The KISA would be on the D-Maillon. If you just have a rope threaded through the KISA with each end being a cowstail, if you fall whilst both cowstails are clipped in then the amount of rope slippage through the KISA is limited. Or am I getting it completely wrong?

 

[PaulW]

https://starlessriver.com/shop/cowstails_footloops/kong_kisa

And yes attach to D-maillion

 

[JoshW]

yes the slippage would be limited. would just slip until both "long" and "short" were tight. I think the idea is that it takes a big fall factor for it to thread back through though?

 

[Tommy]

Thanks again Mark, as an experiment I will change my current set up to incorporate a Shunt in the place of the Prusik knot, I assume slippage at 3kN and a longish cowstail should be okay (I already have the Shunt and often carry it caving anyway for some reason).

I'd looked at the Kong Kisa previously. It makes sense to have the 'Y' setup you suggest Madness, falling with both cowstails clipped or only the long cowstail doesn't seem like there would be much shock absorption as JoshW says.

In fact this can be seen in the Kong usage manual (http://www.kong.it/en/2-products/items/f8-ferrata-kit/p326-kisa), which suggests the impact force will be reduced down to around 5-6kN instead of 13kN for an 80kg test mass falling 5m, with and without the device respectively (page 20). The snipping attached below is from page 60 and shows a Via Ferrata lanyard/cowstail pair meeting in a Y shape with the leg of the Y being a rope passed through the Kisa. This image implies having a rather long 'leg' of rope (5m as per the test?) and coiling it neatly after setting the length on the lanyard side of the Kisa, 3-5cm. This coil has a limiting knot or sewn loop at the end of the rope connected to a karabiner to prevent a fall off the end in a worst case, I'd imagine something like icy or wet rope.

This is inferred from a quick peruse of the manual on my 30 minute lunch break, so take it with a pinch of salt.

 

[Bob Mehew]

I did try out a King Kong on the rope test rig but the rope pulled out of the device.  I can't quickly find the peak force from that try. 

Sorry but on a quick read I am unclear as to what you want to achieve and don't have time to sit and ponder.  If you want to send me a sketch of your desired set up, I could at some stage test it out on the instrumented rope test rig.

The highest force I measured using 0.375m and 0.75m length 10mm dynamic rope samples with Fig 8 knots was under 6kN.  So you should get an impact of much under 6kN provided the knot was relaxed before hand (only subject to your body weight), given your body is not made of steel (excepting Superman of course).

 

[Mark Wright]

Thanks again Mark, as an experiment I will change my current set up to incorporate a Shunt in the place of the Prusik knot, I assume slippage at 3kN and a longish cowstail should be okay (I already have the Shunt and often carry it caving anyway for some reason).

You need to be very careful with Shunts as they can actually start to slip at around 2.25kN and you don't have to fall very far to generate those sorts of forces. Shunts obviously need somewhere to slip to so be very careful to ensure they can. If the slippage is hindered in any way they could break. The rope will likely pop out of the device as the side opens at around 4kN - 4.5kN!!!!

As far as the often mentioned 6kN forces allowable on a body (in a work situation) are concerned, don't be under any illusion that this won't hurt, I can assure you it will really hurt.

I have to agree with Simon about too much emphasis being put on cow's tail configurations. Simple is usually the best. Introducing all sorts of additional equipment into the cow's tail system is just introducing something else that can go wrong.

The Kisa system is designed primarily for use on a via ferrata where Fall Factors of up to FF5 are possible. If you only take a small fall, as would be the case in a normal caving situation, its unlikely to slip at all. In these cases a knot is probably the best energy absorber, so long as you regularly re-tie them or slacken them off between trips.

Mark

 

[Tommy]

"Introducing all sorts of additional equipment into the cow's tail system is just introducing something else that can go wrong."

Very true, I set this up on my harness and it looked a bit silly. The Shunt was too close to the rest of the gear for my liking.

"You need to be very careful with Shunts as they can actually start to slip at around 2.25kN...If the slippage is hindered in any way they could break. The rope will likely pop out of the device as the side opens at around 4kN - 4.5kN!!!!"

And if I needed more reason to steer clear for now then that aught to do it...

"In these cases a knot is probably the best energy absorber, so long as you regularly re-tie them or slacken them off between trips."

This is a habit I have yet to form, but will endeavour to do so from now onwards, thank you for the reminder.

Hi Bob, I'm not trying to achieve anything in particular (for now), just enjoying thinking and playing with gear really.

"If you want to send me a sketch of your desired set up, I could at some stage test it out on the instrumented rope test rig."

We've exchanged a couple of emails before about a project Henry pointed me towards, although I never got round to getting it going any further with you. It would be good to have a dabble with the test rig sometime, would that be at all possible? I'm based in Sheffield but have wheels and the occasional free weekend.

Thanks again for the discussion folks.