Author Topic: Dyneema shock/safety cords  (Read 3001 times)

Offline Duncan Price

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Re: Dyneema shock/safety cords
« Reply #25 on: June 12, 2018, 03:01:08 pm »
I use a loop of cord to attach my top ascender to my sit harness - it serves all the uses described above and can also be re-purposed into a Prussik loop in case I need a third ascender or have lost one of the others. [I was given this advice 20-odd years ago when I attended a SRT workshop by my local grotto when living in the US - in fact the training started off by teaching us to climb a rope using Prussik knots only rather than mechanical ascenders].

Another "safety item" is the link connecting my top ascender to my footloops and safety loop which is a 12 mm delta maillon that can be exchanged with the D on my sit harness if I mislay it.  Both are alloy and weigh next to nothing.

A final tweak is my foot loop - a loop of cord with a knot in the middle. Normally one or both feet go in the bottom loop but I can step up into the loop formed by the knot to gain height at a re-belay a bit like etriers.

Offline Fulk

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Re: Dyneema shock/safety cords
« Reply #26 on: June 12, 2018, 11:11:03 pm »
Hi Duncan, these comments are made in a genuine spirit of enquiry; I am not trying to wind you up, take the piss or criticize you . . . but realistically, how likely is it that you should ‘mislay’ your ∂-maillon (without simultaneously ‘mislaying’ your harness)? Does it not ‘live’ on your harness? You see, I find that if I have a large-diameter ‘connector’ on my hand-jammer, it makes it somewhat more difficult to get the thing on the rope, so I use a 9-mm MR.

And presumably your using a loop of cord doesn’t make it more likely to get snagged up as you progress through a cave (otherwise you wouldn’t use it)?

As far as I’m concerned, I’ve been using SRT for quite a long time now, but I’m always open to suggestions as to how to improve my set-up – so please take my remarks in this context – i.e. a willingness to look at the way other people do things and maybe learn from them.

Still, we’re all different . . . vive la différence. :)

Offline cavemanmike

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Re: Dyneema shock/safety cords
« Reply #27 on: June 13, 2018, 08:32:25 am »
Call me an old fuddy duddy but I stil use one length of rope  for my foot loop and safety ,as in foot loop fig eight at correct hight, length of rope at arms length.fig eight on harness end  :confused: :confused:

Offline JasonC

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Re: Dyneema shock/safety cords
« Reply #28 on: June 13, 2018, 09:06:50 am »
Like Caveman Mike, I keep my SRT kit simple, to match its user, but I was intrigued by this:

A final tweak is my foot loop - a loop of cord with a knot in the middle. Normally one or both feet go in the bottom loop but I can step up into the loop formed by the knot to gain height at a re-belay a bit like etriers.

- as I can see the upper loop could come in handy for knot passes as well as over-tightly rigged rebelays etc.  Is this what you meant, Duncan?

Offline caving_fox

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Re: Dyneema shock/safety cords
« Reply #29 on: June 13, 2018, 09:09:08 am »
Coincidentally This (a FB video sorry)
came up in my feed today, showing how a croll can self open mid pitch (Irata lvl 2 training course!). It seems especially problematic when there's a lot of bulk (the rope access set-up has two oval krabs at the jammer) at the hand jammer -
Quote
Another "safety item" is the link connecting my top ascender to my footloops and safety loop which is a 12 mm delta maillon
- but even without that, at least two of my dozen or so caving facebook friends have had it happen to them.

If this happens mid pitch, your weight is on the hand jammer, standing in the footloop. If you lose balance here (flailing around in shock for instance) the only thing preventing a fall is your safety link!
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Offline Duncan Price

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Re: Dyneema shock/safety cords
« Reply #30 on: June 13, 2018, 09:25:35 am »
. . . but realistically, how likely is it that you should ‘mislay’ your ∂-maillon (without simultaneously ‘mislaying’ your harness)? Does it not ‘live’ on your harness? You see, I find that if I have a large-diameter ‘connector’ on my hand-jammer, it makes it somewhat more difficult to get the thing on the rope, so I use a 9-mm MR.

I've known other people turn up without a maillon (or equivalent) for their SRT harness having taken their SRT kit apart to clean it.  This tip was given to me by the guy who taught me SRT over 30 years ago and I guess based upon personal experience.  Since my top ascender is a Petzl simple then the D-maillon makes a good hand-stop.

And presumably your using a loop of cord doesn’t make it more likely to get snagged up as you progress through a cave (otherwise you wouldn’t use it)?

I've never had to use it in anger but it has never caused me grief.  Seemed like a good idea when it was presented to me.  Keeping the foot-loops and safety loop separate works for me as I replace my foot loops more often than my safety loop.

Like Caveman Mike, I keep my SRT kit simple, to match its user, but I was intrigued by this:

A final tweak is my foot loop - a loop of cord with a knot in the middle. Normally one or both feet go in the bottom loop but I can step up into the loop formed by the knot to gain height at a re-belay a bit like etriers.

- as I can see the upper loop could come in handy for knot passes as well as over-tightly rigged rebelays etc.  Is this what you meant, Duncan?
[

Exactly - this is one trick that I came up with myself and has been useful on numerous occasions.

Offline Fulk

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Re: Dyneema shock/safety cords
« Reply #31 on: June 13, 2018, 10:15:39 am »
Thanks Duncan – it makes sense now.

Offline aricooperdavis

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Re: Dyneema shock/safety cords
« Reply #32 on: June 13, 2018, 12:33:51 pm »
A final tweak is my foot loop - a loop of cord with a knot in the middle. Normally one or both feet go in the bottom loop but I can step up into the loop formed by the knot to gain height at a re-belay a bit like etriers.

Nice idea. The only major downside I can see to that is that it must be quite difficult to get that length just right?

Offline Duncan Price

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Re: Dyneema shock/safety cords
« Reply #33 on: June 13, 2018, 04:16:42 pm »
A final tweak is my foot loop - a loop of cord with a knot in the middle. Normally one or both feet go in the bottom loop but I can step up into the loop formed by the knot to gain height at a re-belay a bit like etriers.

Nice idea. The only major downside I can see to that is that it must be quite difficult to get that length just right?

I think I discovered it by accident my foot loop was too long so I tied a knot in the middle of it to make it shorter then put one foot in the knot one day in order to gain height at an awkward re-belay.  Looking at my SRT kit which I've just washed from last night's grovel, the loop is made by doubling the rope, tying a fig 8 so far down and then joining the ends twice as far down using a double fisherman's which is the end where your foot/feet goes in.  When I replace my foot loops I use the old one as a template.

Offline cavemanmike

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Re: Dyneema shock/safety cords
« Reply #34 on: June 13, 2018, 07:30:37 pm »
As regards to re-belays I just stand in my pantin to gain any height I might need. Keep your kit simple

Offline marysboy

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Re: Dyneema shock/safety cords
« Reply #35 on: June 14, 2018, 10:11:01 am »
As regards to re-belays I just stand in my pantin to gain any height I might need. Keep your kit simple
those already using the petzl method of clipping jammer with a cowstail have the option of clipping the footloop into the cowstail crab and standing in the loop just created. pantin not required. (keep kit simple?)

Offline Fulk

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Re: Dyneema shock/safety cords
« Reply #36 on: June 14, 2018, 10:17:50 am »
You can gain a useful bit of height (ca. 20 cm) by converting a standard footloop to a lark's head-type loop.

Offline ah147

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Re: Dyneema shock/safety cords
« Reply #37 on: June 14, 2018, 03:38:09 pm »
I took over FF1 fall once onto a daisy chain.

It really, really, really, hurt.

I had a really big padded harness on but also had a tonne of weight attached to me.

I wouldn’t recommend trying it in a caving harness.


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Re: Dyneema shock/safety cords
« Reply #38 on: June 14, 2018, 04:37:08 pm »
Did you stack it in Cresta run, P8?

Offline MJenkinson

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Re: Dyneema shock/safety cords
« Reply #39 on: June 14, 2018, 05:20:33 pm »
Those of you using your long cowstail as your safety link to your hand ascender..

1. Hows the footloop attached to the ascender; maillon, carabiner or just a knot?
2. Do you have a locking carabiner on your cowstail?
3. When you clip your carabiner into the ascender, do you put it through the "other" carabiner or maillon or into the ascender itself?

I ask as I was playing about with this the other week and made a footloop out of some tape I had lying about with a maillon connecting it to the ascender.

My only note is that its possible to twist my cowstail carabiner and force it to unclip from the maillon.  I don't like the idea of switching to a locking carabiner on my cowstail so I guess its just a question of likelihood of this happening/ risk.

Offline topcat

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Re: Dyneema shock/safety cords
« Reply #40 on: June 14, 2018, 07:29:44 pm »

My only note is that its possible to twist my cowstail carabiner and force it to unclip from the maillon.  I don't like the idea of switching to a locking carabiner on my cowstail so I guess its just a question of likelihood of this happening/ risk.

A screw gate not screwed up is a snap.  I've come across this aversion to cowstail screw gates before, but don't understand it.  Use it as a snap if you must, but at least if you feel the need of the extra security, it is there for you.  Assuming you maintain it of course.

Offline Fulk

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Re: Dyneema shock/safety cords
« Reply #41 on: June 14, 2018, 08:08:39 pm »
Agreed, topcat; I've always used screwgates on my cow's tails; most of the time the don't get screwed up, but on rare occasions the extra security they afford makes it worthwhile (in my eyes).

Offline GT

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Re: Dyneema shock/safety cords
« Reply #42 on: June 14, 2018, 09:27:05 pm »
As previously said, for me Marks nailed this.

I really question why people use dynamic rope to their hand jammer, any dynamic loading on a toothed jammer is likely to severely damage the rope.

In my mind putting a section of dynamic rope into the system gives people a false sense of security in that the dynamic properties of the rope will reduce a load on the jammer in the event of a fall and may protect the rope. In my (simple!) mind it's easier to park that idea and use 5-6mm accessory cord and not even consider using a toothed jammer in a situation that could result in dynamic loading.

Offline ah147

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Re: Dyneema shock/safety cords
« Reply #43 on: June 14, 2018, 10:01:41 pm »
Did you stack it in Cresta run, P8?

No. The Nose on El Cap.


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Offline marysboy

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Re: Dyneema shock/safety cords
« Reply #44 on: June 14, 2018, 10:29:24 pm »
Those of you using your long cowstail as your safety link to your hand ascender..

1. Hows the footloop attached to the ascender; maillon, carabiner or just a knot?
2. Do you have a locking carabiner on your cowstail?
3. When you clip your carabiner into the ascender, do you put it through the "other" carabiner or maillon or into the ascender itself?

I ask as I was playing about with this the other week and made a footloop out of some tape I had lying about with a maillon connecting it to the ascender.

My only note is that its possible to twist my cowstail carabiner and force it to unclip from the maillon.  I don't like the idea of switching to a locking carabiner on my cowstail so I guess its just a question of likelihood of this happening/ risk.
Since you ask... standard pair of inglesport cowstails tied with a fig-8 and two snapgate keynose crabs each on a double fishermans knot with long tails. either crab clipped to main lower eyehole on old-style petzl basic jammer (or upper pair of holes and also around the rope for sloping lines). separate footloop tied in 25mm tubular tape with small overhand loop at top connected to smallest lower hole on petzl basic using a small steel delta maillon. the small deta maillon is not part of the fall load path. the cowstail crab clips the jammer directly, and not via any other crab or maillon partly for the reason you describe.

clearly as this thread has highlighted my chosen kit setup has positives and negatives and like everything else it is a compromise of many factors. just happens that its a compromise that im happy with.

Offline marysboy

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Re: Dyneema shock/safety cords
« Reply #45 on: June 14, 2018, 11:20:42 pm »
I really question why people use dynamic rope to their hand jammer, any dynamic loading on a toothed jammer is likely to severely damage the rope.
since you really question it i will form a response to this and your other points. i use dynamic rope on my hand jammer to reduce the dynamic loading on my toothed jammer compared to static rope, and thereby reduce the liklihood of rope damage or parting in an unplanned fall onto that jammer/rope combo. i understand there is a hazard of damaging the rope and i choose an accepted method to reduce that loading. i do not believe that 'any' dynamic loading is likely to severely damage the rope as you say. if that were the case there would be a lot more stories of broken ropes but this seems to be exceptionally rare.
Quote
In my mind putting a section of dynamic rope into the system gives people a false sense of security in that the dynamic properties of the rope will reduce a load on the jammer in the event of a fall and may protect the rope.
studies shared above show that dynamic rope *does* reduce the load in the event of a fall. it makes sense to me that this would help protect the rope. by the way i am not advocating using jammers in a planned way to catch big falls and like most people i really don't want to fall onto a jammer. but, slips on to jammers do happen in the real world and there is a very easy way of mitigating some of that risk with the method described. i don't think its a false sense of security but a considered approach to mitigating foreseeable hazards.
Quote
In my (simple!) mind it's easier to park that idea and use 5-6mm accessory cord and not even consider using a toothed jammer in a situation that could result in dynamic loading.
it seems you choose to dismiss the manufacturers instructions and put greater reliance on your own vigilance with an accepted increase in risk of human error that your non-standard use requires. thats a trade off you choose to make and i'm not forcing you to adopt any given system.

but there are foreseeable circumstances of dynamic loading onto a toothed jammer with the conventional setup that are somewhat outside of the users control. e.g. imagine prussiking up towards a bolt rebelay and when nearly there, the bolt fails, dropping you until the backup bolt takes the weight. could that occur with your setup and do you use toothed jammers? i believe it's worth considering.

further, imagine ascending a sloping traverse line that might be quite long. in that situation i would consider using a jammer on the sloping line with the aim of arresting any fall if i slip. would you consider that? likely the alternative would be clip the sloping traverse line with a cowstail and accept a zipline fall down to the next traverse anchor, and whatever uncomfortable landing might wait there. which is safer?

all the above assumes 'dynamic' load to mean any sudden loading of a rope that was previously slack, usually in an unplanned way. if you have a different understanding of dynamic fall to me then please share.
« Last Edit: June 14, 2018, 11:34:33 pm by marysboy »

Offline Fulk

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Re: Dyneema shock/safety cords
« Reply #46 on: June 14, 2018, 11:26:34 pm »
GT:
Quote
In my (simple!) mind it's easier to park that idea and use 5-6mm accessory cord and not even consider using a toothed jammer in a situation that could result in dynamic loading.

So would you like to describe the set-up you use for prusiking?

Offline marysboy

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Re: Dyneema shock/safety cords
« Reply #47 on: June 15, 2018, 08:53:50 am »
In my mind putting a section of dynamic rope into the system gives people a false sense of security in that the dynamic properties of the rope will reduce a load on the jammer in the event of a fall and may protect the rope.
studies shared above show that dynamic rope *does* reduce the load in the event of a fall. it makes sense to me that this would help protect the rope. by the way i am not advocating using jammers in a planned way to catch big falls and like most people i really don't want to fall onto a jammer. but, slips on to jammers do happen in the real world and there is a very easy way of mitigating some of that risk with the method described. i don't think its a false sense of security but a considered approach to mitigating foreseeable hazards.
this aspect of my recent post:- "...a considered approach to mitigating foreseeable hazards" is too general and i would prefer to be read "a considered approach to mitigating a foreseeable hazard"

i think it is important to explicitly qualify this as being a specific mitigation to the consequence of a fall onto the handjammer safety cord (i.e. keeping us on the topic raised by the OP and the issue i was responding to in GT's post).

more generally this thread has prompted me to think again and in great detail about how my kit is assembled and used. other people's input has been very useful to this. cheers everyone  :beer2:

Offline andrewmc

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Re: Dyneema shock/safety cords
« Reply #48 on: June 15, 2018, 08:54:42 am »
As previously said, for me Marks nailed this.

I really question why people use dynamic rope to their hand jammer, any dynamic loading on a toothed jammer is likely to severely damage the rope.

In my mind putting a section of dynamic rope into the system gives people a false sense of security in that the dynamic properties of the rope will reduce a load on the jammer in the event of a fall and may protect the rope. In my (simple!) mind it's easier to park that idea and use 5-6mm accessory cord and not even consider using a toothed jammer in a situation that could result in dynamic loading.

To some degree I agree with you (and used to use a bit of the Beal 5.5mm dyneema core stuff for my 'safety' cord. Any fall which is more than a few metres below an anchor is fine anyway as the rope will take the load. But tests show that a FF2 onto cowstails tied with dynamic rope tied with appropriate knots (barrel knots and Fig 8) come in around the 6kN mark, while sewn lanyards are terrible and using static rope bumps the load up slightly. 4-6kN is about also the rope-tearing threshold. So I think it's not completely unreasonable to say the following:
 1) It is probably very difficult to tear a sheath taking a FF1 fall onto an ascender connected by a dynamic rope cowstail
 2) This is probably not true for a truly static lanyard.

So possibly it's not an entirely false sense of security - I now use a standard dynamic safety cord. Falling onto an ascender remains a bad idea.

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Re: Dyneema shock/safety cords
« Reply #49 on: June 15, 2018, 12:05:22 pm »
I switched to using my long cowstail as an attachment point for my hand jammer some time ago and have not looked back since. This is combined with an adjustable petzl dyneema footloop. When not ascending or rigging I keep my ascending gear on a gear loop out of the way. I have never dropped a hand jammer despite being prone to this kind of fecklessness. this reduces clutter on my harness and saves weight: perfect.

Regarding falling onto jammers: early in my alpine caving career in Austria I was rigging a traverse line with my hand jammer (at the time on a separate static safety cord) and a short cowstail clipped into a progression knot as protection. I was crossing a big rock bridge and as I crossed it collapsed, leading me to swing around 5m into the opposing wall. the hand jammer was not hanging loose, and consequently did not take a big force (less than ff1). the short cowstail did not come tight. Thus the jammer was the only thing protecting me at the time. As long as you use your jammers properly (ie without the chance of a dynamic shock load) then I see no reason why a jammer shouldn't be used as protection in these instances rather than just an aid to progression as seems to have been suggested. Obviously its a good idea to back it up. However, if the jammer had damaged the rope in my case then the back-up would have been rendered void anyway as the damaged section of rope would have been above the back-up. Something to think about.

This leads onto another point: what do people think is the best way of protecting a traverse such as this without using a descender, which is sub-optimal in a number of ways (takes ages, uses a lot of excess rope, clumsy)? If bolting a new traverse (no P bolts to clip into) which is very exposed (ie few useful foot and handholds), I generally use my jammer on my short cowstail as a positioning tool backed up by my long cowstail (screwgate) clipped to a knot above the jammer (to avoid the situation I outlined above). If there are truly no real holds, I would use a skyhook for positioning, but then this has to go on a cowstail or other attachment point. this is where carrying an extra attachment point comes in handy. Obviously you can clip the previous bolt and just reach out sideways from there, but then you would end up using a shit load of bolts on a traverse line, especially if you have short arms like me.
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