Rescue knife: yes or no?

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Kosta
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Rescue knife: yes or no?

Post by Kosta » 31 Aug 2018, 09:11

Hi,
I've long been a supporter of carrying a knife with me during abseils and making sure I'm able to access and open it with only one hand so I can cut myself loose in case I get stuck by some hair in my descender or if the self belay catches in a precarious situation where I don't want to muck around with getting my prusiks out.

I had it happen a couple of times, that I got a little bit of hair caught in my descender (one time it happened in a small water fall) and I was very glad that I could simply cut it off in a few seconds and continue with my descent. So I wouldn't want to miss my knife on me.

I recently came across an article by Richard Delaney where he argues against the usefulness of a knife during abseils:
https://www.ropelab.com.au/rescue-knife/. He argues, that in almost all situations, there are better methods and that operating with a knife near rope is too dangerous. He considers the situations where he would use it quite contrived and unlikely.

What do you guys think about knifes? Is it useful or not? And should we teach people to carry one or not bother?



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Re: Rescue knife: yes or no?

Post by Bayjam » 31 Aug 2018, 15:54

I've only recently started carrying an emergency knife for that "one in a lifetime" issue that might arise. I hope to never use it. But I also don't recommend others in the group take one.. We don't need multiple knives flying around particularly less experienced canyoners. I can see the benefits and the dangers, so it must be treated with utmost respect

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Re: Rescue knife: yes or no?

Post by LachlanB » 01 Sep 2018, 15:42

I always carry a knife for abseiling activities in the field. Richard's article might be right about other options. But if you don't have a knife, the backup option to cut the hair/rope/cord/whatever isn't available. At least it gives me a way to get a casualty off rope relatively quickly. The idea of harness hang syndrome scares me- there might only be 10min to get someone off rope.

But my knife doesn't live on my harness; rather I'll keep it in my pack, which'll generally either be on my back or dangling just below me. I figure that's a good compromise between quick access and having more junk on my harness. The pliers that come with my knife are very useful too, for opening jammed krabs and the like.

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Re: Rescue knife: yes or no?

Post by tom_brennan » 06 Sep 2018, 13:10

I've never carried one. I can see Richard's points. However, I can also still see value in carrying one.

It's just that reaching for the knife when you're around a loaded rope should be the last resort, not the first.

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Re: Rescue knife: yes or no?

Post by T2 » 07 Sep 2018, 12:26

Interesting thoughts and an interesting read.

I've always carried a knife on my harness -- or felt guilty about it if I left it at home. It's always been one of those things that is "good to have", but probably provides more psychological security than practical benefit. But I totally agree about the use of a knife near a loaded rope being a last resort.

Personally, I have never used mine while on rope. In fact, the only time my knife has been used in anger was earlier this year in Tassie. The least experienced member of our group managed to get a knot in the rope caught in his descender. I got prusiks up to him so he could remove his descender to clear the knot which had become caught in the device. By the time he was ready to continue, cold fingers and fatigue saw him unable to release the prusik. I sent my knife up to him so he could cut the cord. He didn't need to cut near the abseiling rope, so it was low risk. It wasn't the most ideal option, but in a situation where someone is in the spray of an 80m waterfall with limited communications and no easy way for someone more experienced to get up or down to him, it was an option I was glad was available to us.

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Re: Rescue knife: yes or no?

Post by Paul G » 07 Sep 2018, 21:33

Seems to me that carrying one but being thoroughly aware that it's a risk and last resort is OK. I used one in a recent rescue where we came across someone from another party who had been hanging for nearly an hour - having got them attached to a top belay the priority seemed to be getting them down asap and getting medical assistance, not setting up prussics and unweighting the jammed device, so we just cut the other rope and lowered.

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Re: Rescue knife: yes or no?

Post by LachlanB » 07 Sep 2018, 22:22

Paul G wrote:
07 Sep 2018, 21:33
Seems to me that carrying one but being thoroughly aware that it's a risk and last resort is OK. I used one in a recent rescue where we came across someone from another party who had been hanging for nearly an hour - having got them attached to a top belay the priority seemed to be getting them down asap and getting medical assistance, not setting up prussics and unweighting the jammed device, so we just cut the other rope and lowered.
Wow, that sounds like it would have been a rather confronting situation to come across. :o
Mind if I ask what had happened?

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Re: Rescue knife: yes or no?

Post by T2 » 08 Sep 2018, 13:02

LachlanB wrote:
07 Sep 2018, 22:22
Wow, that sounds like it would have been a rather confronting situation to come across. :o
Mind if I ask what had happened?
Lachlan, Paul has just posted the details of this rescue he was part of here: viewtopic.php?f=14&t=148

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Re: Rescue knife: yes or no?

Post by LachlanB » 08 Sep 2018, 21:36

*facepalm* Didn't see that, hidden down the bottom. Thanks for pointing it out.

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Re: Rescue knife: yes or no?

Post by Kosta » 10 Sep 2018, 11:21

It seems, that the main concern about a knife is less its usefulness but the potential danger of inadvertently cutting the rope.

I might do some testing with an old piece of rope to see how fast it actually gets cut through.

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Re: Rescue knife: yes or no?

Post by Kosta » 16 Sep 2018, 09:35

Yesterday, at T2's fiddle stick introduction, we managed to do a couple tests for cutting a loaded rope.

We did three tests:

1) Cutting it as you would deliberately cut a rope. The knife went through easily. I needed two cuts, but if the first one was a bit more determined, I'm sure one would have done the job.

2) I just thrashed onto the rope at various angles to see what happens if you hit the rope but nor full on. The rope did get clear damage from the start, but it took a few hits until the rope actually broke.

3) I hit the rope with the blade full on. The rope goes through with a single solid hit. In the video, you see me hit it three times. The first one, I basically missed the rope. The second hit went half through. The third hit went full through, but at a slightly different spot. So the rope was effectively severed with a single hit.

So yes, you do want to be careful when using a knife near a loaded rope. But it seems, that in order to cut the rope with one blow, it still needs to be a strong(ish) and well angled cut or hit. It doesn't fully go through on first touch. Thus, I don't think I'd completely dismiss the option of cutting something in an emergency, but I'd definitely consider the risk of accidentally damaging an essential rope in the course.

Other lessons learned: a harness keeps you in a sitting position. Thus, if you are hanging and then land on your feet, you are off balance and fall over...



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Re: Rescue knife: yes or no?

Post by LachlanB » 16 Sep 2018, 12:27

Interesting. I didn't expect the results to be quite so dramatic. Thanks for the experiment! :)

The first test in the video was the most concerning to me as it looked like the most accurate representation of, say, cutting hair free from a jammed descender, mishandling the knife and hitting the rope. What diameter rope were you using?

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Re: Rescue knife: yes or no?

Post by Kosta » 16 Sep 2018, 13:27

I'm not 100% sure what type of rope it was and what history it had. It was an old piece that T2 had lying around. But looking at it, I'd say it's 9 mm, probably a Tendon static.

The knife was a Petzl Spatha like the one in this picture:
Image

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Re: Rescue knife: yes or no?

Post by T2 » 16 Sep 2018, 20:58

I think that rope probably was a 9mm Tendon, but I don't actually remember its origins. It certainly wasn't a particularly thin rope, nor was it particularly worn or abraded, so those factors definitely didn't play a part in how easily it cut.

Even knowing that loaded ropes cut easily, I was still surprised by just how easily it sliced. For me, the big lesson from that is that if you absolutely do need to use a knife near a loaded rope, do so carefully, aiming the blade along side or away from the rope. The knife rubbing alongside the rope did very little damage by comparison to even a soft impact straight on.

Having done this experiment, the next one I'm now keen to see is how easily a loaded rope can be cut when sliding sideways across a sharp edge. Seeing how easily the blade could cut the rope, it really does reinforce the need to be careful when abseiling to ensure you don't go to the side and get swung back across. Likewise, jumping over an edge so the rope hits it sharply also seems particularly risky to me know. Just another reason to make sure you abseil in a deliberate, careful, intelligent manner to remove the potential risk posed by sharp rocks.

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Re: Rescue knife: yes or no?

Post by Bron » 17 Sep 2018, 21:01

I was quite surprised at just how easily the loaded rope was cut. I'd always heard that it was easy, but still expected it to be a bit more difficult than that. I still think having a knife reasonably accessible in the group is a good idea - certainly was glad we had one on the one occasion we needed it. This does serve as a good reminder though that if you do need to use a knife on a loaded rope - do so mindfully. Just having the piece of mind to turn the knife around and cut away from the rope rather than towards it would not take much time, but could prevent a cut rope and its aftermath

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Re: Rescue knife: yes or no?

Post by tom_brennan » 21 Sep 2018, 09:00

Good to see some live testing. I'm happy that no-one ended up impaled by a knife!

Having sliced a lot of cord under moderate tension, I was more surprised at the resistance of the rope in the video. Though once it started to go, it went explosively!

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Re: Rescue knife: yes or no?

Post by Kosta » 28 Jan 2019, 21:51

So... I was on a canyoning trip recently where we had a bit of a mishap that I thought might be worth sharing in this context.

We were doing a 20 m drop. I went first. Due to an oversight of the trip leader at the top, the person going down second carried the safety rope that should have stayed at the top. And as if it was planned, the third person coming down who was relatively inexperienced got her hair stuck. It was a smallish strand of hair that has escaped her helmet near her temple.

Luckily, she was relatively close to the end with her feet maybe 1.5 m off the ground - too much to be able to actually get to her easily to assist her hands on, but just low enough to be able to pass things to her.

Option 1: rescue from the top - the trip leader comes down on the safety rope and ties prusiks for the stuck person so she can take the weight of her descender: not possible because the safety rope was at the bottom.

Option 2: give her prusiks and let her tie them herself: good luck teaching someone to tie and use prusiks in such a situation.

Option 3: prusik up myself. Takes quite a while and I would probably need several sets of prusiks. After all, while I'm below her, I am still loading the rope, so it's impossible to unload the descender. So I would have to pass her descender and then set up prusiks for her. Or come from below and set up prusiks for her and then go back down. Or come from below and cut her hair. I've never tried any of this and I only had three prusik loops on me (the other guy might have had some as well though, not sure). In any case, it's a lot of mucking around.

Option 4: pass her a knife and explain to her to be very careful with the rope and watch her every move while cutting the strands of hair off.


Option 4 seemed the most reasonable here. It was quick to implement and the danger of cutting the rope small because I was able to watch her and she was close to the ground anyway. It worked.

I just thought I share this as an example of a successful use of the knife.

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Re: Rescue knife: yes or no?

Post by Vertical_Wookiee » 20 Feb 2019, 20:46

T2 wrote:
16 Sep 2018, 20:58
Having done this experiment, the next one I'm now keen to see is how easily a loaded rope can be cut when sliding sideways across a sharp edge. Seeing how easily the blade could cut the rope, it really does reinforce the need to be careful when abseiling to ensure you don't go to the side and get swung back across. Likewise, jumping over an edge so the rope hits it sharply also seems particularly risky to me know. Just another reason to make sure you abseil in a deliberate, careful, intelligent manner to remove the potential risk posed by sharp rocks.
It's remarkably easy to core shot 9mm nylon rope. So much so I wonder why people aren't more aware of it. Ropes just seem to 'get damaged' without people usually seeing when or specifically how.

When I demonstrate how easy it is to damage a single strand of rope with 80kg hanging on it over a blunt rock edge my course participants are usually pretty flabbergasted!

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