UKBouldering.com
the shizzle => equipment => Topic started by: User deactivated. on July 17, 2023, 11:07:56 am
-
A new route I've been headpointing on a semi-static (10mm Petzl Club) involves a huge dyno which I haven't been able to latch yet and therefore have repeatedly been taking quite a lob onto the rope. I'm using a grigri to self-belay which i'm well aware is far from the safest way of doing things, but I do have my pads laid out quite a way below... At the end of my session, it was extremely worrying to find a part of my rope that was out of view in this state:
(https://i.ibb.co/3C2vYPm/IMG-20230717-095652.jpg)
The damage was somewhere over the top of the route, around 5m from the end of the 30m rope. Unfortunately, I can't just cut this 5m off as I can feel that the sheathing has come loose from the core for another 10-15m down the length of the rope. This was a new rope with no prior damage and I was using two rope protectors in the obvious rub points. Could this have occurred due to:
1. falling hard repeatedly onto the static rope (not enough to hurt though - there's still some stretch); or
2. must it have been rubbing somewhere?
On the info provided so far, I would be leaning towards 2, but now for the weird part...
I've had 2 sessions previously on this route on a different rope (another Petzl club that was old and a bit frayed in places but still usable). After the first session, I didn't notice any damage, but I don't think I'd realised 'the move' was a dyno until right near the end. During the second session, the same rope damage occurred but to a lesser extent because it was in a spot that was visible and I soon stopped climbing on it. In this instance, the rope definitely wasn't rubbing where the damage occurred, but I can't guarantee that there wasn't any previous damage in that spot.
This makes me lean towards number 1. If this is the case, would the best way to resolve it be to make the anchor with a static and then climb on a dynamic?
-
Interesting! One for Dan at the BMC.
Like you say the obvious thought is abrasion. I’ve had a couple of occasions while equipping solo or TR solo where’ve got to the top to discover abrasion damage despite having thought I’d protected the rope (or occasions where I didn’t bother protecting because I thought I could get away with it and didn’t..).
But the info about repeated dyno’s, and there being no obvious abrasion point, makes me wonder if you exceeded the limitations of the rope’s dynamic strength. To pass EN1891 dynamic test for low-stretch ropes, the rope must hold a minimum of 5 factor 1 falls with a 100kg mass (type A rope) or 80kg mass (type B rope).
Your’s is a type A rope.
How many falls, how far, how much rope out between you and the top, and what do you weigh?
-
Cheers for info Pete.
Yesterday, on the new rope I probably had around 15-20 attempts at the dyno. I have to climb into it to get established, so there's a little bit of slack before I even attempt the jump, then I'm jumping as hard as I possibly can to make the distance, so the fall is probably around 2m I would guess. Between myself and the anchor i'm not sure but would expect it to be in the range of 10-15m (sorry that's quite big range). Currently, I am a svelte 80kg, although probably more like 82-83kg mid day, fed and watered with clothes and a harness on.
Another thing I just noted is that there doesn't appear to be any damage to the exposed strands, possibly further indication that it wasn't due to rubbing?
-
It will have been due to rubbing. Sheaths simply don't fail mid-rope due to loading unless already badly damaged.
The relationship between loading and a rope's resistance to abrasion is not linear, at all. So most likely at the peak impact force of you landing the fall, when the rope was at it's maximum load and stretch, you had contact with an unprotected sharp. It could be quite small, and wouldn't need to be an acute angle. It is often quite hard to anticipate how the belay takes the peak load unless you can watch it take the fall.
I'd suggest changing your rigging so there are multiple strands between the belay and the bit of rope you can see (i.e. where a lower-off would be). This will share the loads, reducing stretch, reducing the likelihood of rope damage and add redundancy if damage does occur. And increase your rope protection measures obvs.
-
Wont have stopped this, but ive started rigging my rigging rope as id normally do and have it come down to a metre or so from the edge of crag. Couple of knots in the end, then clips two rope access wire strops (ones with plastic coating) into the knots and hang over edge. Couple of krabs in this then your rope for working attached to that. You should now, ideally be able to see knots.
Also ive started using a rescucender instead of a shunt. Much better imho.
-
The damage was somewhere over the top of the route, around 5m from the end of the 30m rope.
:o
I recall reading a Yosemite accident report that suggested fixed ropes are particularly vulnerable to abrasion around 5-7m from an anchor. The context was a climber jumaring a fixed-rope but working a route involves a similar repeated bounce on the rope, sawing it as it stretches and relaxes. The rope touched the rock at around 5m but there was no edge to speak of and the climber judged it safe enough with disastrous consequences. The report suggested at shorter distances the rope moves less relative to the rock; at longer distances the abrasion is spread over more of the rope.
I have no idea if any of this is true, if it also applies to semi-static ropes, or even if I have remembered the report correctly.
-
Yeah that's true - there's a sweet spot where there is enough stretch to cause movement but not enough to spread it over the rope. Granite typically has plenty of tiny crystals that can do damage in such circumstances.
Edelrid have done some very good research in recent years (https://edelrid.com/gb-en/knowledge/knowledge-base/cut-resistance-of-ropes) which highlights the importance of applied load.
The overall conclusion here is simple and quite obvious. In order to increase the overall safety regarding cut resistance of a given rope system, one should try to reduce the weight that is applied within the system before looking for any other solutions
-
Firstly, I can't imagine the thoughts you had seeing your rope in that state topping out/walking round to the top!
Secondly:
1. falling hard repeatedly onto the static rope (not enough to hurt though - there's still some stretch); or
2. must it have been rubbing somewhere?
As JB said and Duncan explained in his post, it's option 2. If you can drop it off/send it to Dan at BMC HQ in Didsbury we can have a look at it for you?
-
Photo isn't great but there looks to be obvious abrasion damage to the sheath adjacent to the failure point.
-
The main takeaway I've learned from this is that, judging from your photo, climbing is still very much a middle class sport.
-
I'm not sure how the bag came into my posession, it's actually quite embarassing. I'm an Aldi shopper and can't recall ever visiting a Waitrose! Whilst i'm a homeowner and work as an engineer, I grew up in Doncaster as the son of a coal miner, my mates are plumbers and the theatre sounds fucking boring.
-
:lol: