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Top roping joined ropes

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 JStearn 18 Oct 2020

I am planning to top rope ice at this crag:

 https://climbinggeorgia.wordpress.com/2012/03/29/ice-climbing-in-ateni-valley/

The route is 60m with anchors at the top and the site above suggests taking 2x60s. In some of the pictures it is clear the belayer is on the ground and the ropes are presumably tied together. I could belay from above on a single 60 or set a (screw) anchor halfway but I would prefer to belay from the ground. Am I right to be concerned about the amount of rope stretch on 120m of rope (i.e. enough to catch a crampon)? Any other issues to consider with this setup? The knot shouldn't be a problem as it won't need to be passed.

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 spenser 18 Oct 2020
In reply to JStearn:

The rope stretch is going to be pretty substantial if they come off low down the pitch. I'd certainly far rather be being belayed from above rather than below. 

The knot joining the ropes is also rather weaker than the rope itself.

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 Rick Graham 18 Oct 2020
In reply to spenser:

A well tied knot isn't an issue .

The % stretch under bodyweight is included in the rope tests but any percentage of 120m is going to be a problem .

Edit . Typical static stretch for half rope is 7%, or 8.4 metres over 120m! Hence the advice of getting the stretch out of a long top rope by loading it from a safe position near the ground before setting off up the pitch.

Post edited at 19:48
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 deepsoup 18 Oct 2020
In reply to JStearn:

Do you know any sea cliff climbing heroes (or cavers) with a 120m static (semi-static, LSK, whatever you want to call it) rope they could lend you?  The rope stretch would probably still be quite substantial, but significantly more manageable I would think.

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 GrahamD 18 Oct 2020
In reply to JStearn:

Rope stretch isn't the only potential problem.  120m of rope is going to be heavy !

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 JStearn 18 Oct 2020

Can I use the figure for static elongation (8% for a Beal Joker, so ~9.6m stretch near the bottom of the route. Seems huge?) I'm reluctant to set the anchor half way as I am planning to introduce some indoor climbers to ice so will want to leave the ropes set up all day and there is no way to inspect the integrity of the anchor easily throughout the day by the looks of the photos (not sure on the crag's aspect). The locals seem to toprope happily enough but in my experience, that is no guarantee of safety here!

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In reply to JStearn:

Can't see any reason why you couldn't have one low stretch "static" rope joined to one dynamic if that was all that was available.. Half the stretch and progressively less as height gained if the dynamic was being taken in by the belayer.

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 smithg 19 Oct 2020
In reply to JStearn:

It'll be fine, so long as the belayer works hard to keep as much tension as possible in the rope.

Before the climber sets off, the belayer gets the rope as tight as they can and lock off. They both try to sit down with their weight on the rope. If this results in them sitting on the floor, it's not tight enough, they need to take in the extra stretch as they stand back up. Repeat until they're both able to hang side by side just off the ground.

Now as the climber starts to climb, the belayer has to haul with their full weight on the rope as they're taking in, to keep the tension. The higher the climber goes, the less rope in play so the easier it gets.

The climber should climb slowly enough to allow the belayer to keep up and in case of a fall, should try to sit back into space to avoid catching a crampon. 

Pre-climbing/abseiling the line and placing a couple of long runners on the climber's rope could prevent a long swing if they do come off low down and aren't exactly in line with the anchors.

Edit: The belayer really needs to be heavier than the climber, maybe have an extra person hang off the back of their harness to help.

Post edited at 22:58
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In reply to smithg:

That would be a supremely unpleasant experience for the climber.

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In reply to JStearn:

>  I'm reluctant to set the anchor half way as I am planning to introduce some indoor climbers to ice so will want to leave the ropes set up all day and there is no way to inspect the integrity of the anchor easily throughout the day by the looks of the photos

If your top anchor is bomber just extend that halfway down the crag with a static rope to a suitable point to use as your toprope anchor. This assumes the static won't get worn by repeated rubbing on the same spot. Maybe use two lengths of rope down the crag.  I'd consider using a different crag / line, if this is a novice scenario you need to be able to communicate with the climber easily and that's not possible when they're 30m or more away.

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 deepsoup 20 Oct 2020
In reply to Toerag:

> If your top anchor is bomber just extend that halfway down the crag with a static rope to a suitable point to use as your toprope anchor.

I'm not entirely sure if this is a serious suggestion.  So just in case it is - I feel I should point out that I'm pretty sure this is a terrible idea!

Static rope, the kind you can buy in a climbing or caving shop anyway (to EN1981) is not static. 

Of course no rope is completely static, every material stretches at least a bit, so there's a little bit of stretch even in a rope made of kevlar, dyneema or steel.  But a "static rope" is actually designed to stretch a bit, and because the standard specifies a maximum allowable impact force in a similar sort of way to the standard for a dynamic rope, it won't meet the standard if it's not stretchy enough. 

'Static' rope is actually stretchy enough to use for top-roping in just about any scenario you can think of (certainly this one!) as long as you don't allow ludicrous amounts of slack to build up.  (ie: As long as you don't start to introduce a fall-factor comparable to leading.)

In practice I believe the elastic elongation of a 'static' rope (such as caused by a top-roped climber weighting a tight rope with no serious impact from a fall) is about half that of a dynamic rope.  (Somebody please correct me if I'm wrong about that - don't have a copy of either standard or numbers to hand right now.)  If the OP wants to about halve the amount of rope stretch compared to a dynamic rope, it could be done by using a 'static' rope instead.

Now, think about Hooke's Law.  For loads that are low compared to the strength of the rope, as you would hope to be the case in a top-roping situation, the ropes are more or less entirely elastic and more or less obey Hooke's Law.  The amount of stretch is proportional to the length of the rope and also to the load put on the rope.

30m is a long way to extend the anchor - that's a lot of rope.  If the climber falls, the load on the 'anchor' rope is more than the load on the climbing rope, potentially up to twice as much, because it has both climber and belayer hanging off it.  For every inch the 'anchor' rope stretches, the climber drops two inches because the anchor has moved an inch closer to the ground and also an inch closer to the belayer.  So the bottom line is that extending the anchor half way down the crag with 'static' rope will quite probably increase the distance the climber will drop on 'rope stretch', not decrease it.

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In reply to deepsoup:

> I'm not entirely sure if this is a serious suggestion.  So just in case it is - I feel I should point out that I'm pretty sure this is a terrible idea!

Always point stuff out when considering safety, and thanks for doing so!

> 30m is a long way to extend the anchor - that's a lot of rope.  If the climber falls, the load on the 'anchor' rope is more than the load on the climbing rope, potentially up to twice as much, because it has both climber and belayer hanging off it.  For every inch the 'anchor' rope stretches, the climber drops two inches because the anchor has moved an inch closer to the ground and also an inch closer to the belayer.  So the bottom line is that extending the anchor half way down the crag with 'static' rope will quite probably increase the distance the climber will drop on 'rope stretch', not decrease it.

I'd not considered that and I've run the maths and you're right - the 'moving pulley' effect adds a significant multiplier. If we assume static stretches 4% on bodyweight..... but bodyweight is doubled so it stretches 8%, then we have the following drops when the climber falls off from the following heights on a 30m pitch length:-

Fall off height      Extended static fall with 60m dynamic   Full 120m dynamic bottom rope fall

5m                       9.4m                                     9.2m

10m                    9.2m                                      8.8m

15m                    9m                                          8.4m

20m                   8.8m                                        8m

25m                  8.6m                                         7.6m

So the climber needs to be 5-10m up before they'll avoid hitting the ground. The most important point is that the climber is looking at an unacceptably long fall whatever method is used.

If we use statics everywhere we get the following fall lengths:-

5m               8.3                                              4.6

10m             8.2                                              4.4

15m             8.1                                             4.2

20m           8                                                  4

25m             7.9m                                            3.8

Which is still bad even in the best case. Probably better to avoid bottom-roping a 30m pitch completely, or making a good multi-screw belay at 30m backed up from the bomber belay to prevent a catastrophe.

Post edited at 17:26
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In reply to Toerag:

> If your top anchor is bomber just extend that halfway down the crag with a static rope to a suitable point to use as your toprope anchor. This assumes the static won't get worn by repeated rubbing on the same spot. Maybe use two lengths of rope down the crag.   <

FWIW I remember abseiling most of the length of a 150'  dynamic half rope to a ledge on Castell Helen. To avoid leaving gear on the final shorter abseil to the bottom I tied a fig8 on bight as high as possible on the half rope, clipped the middle of the single climbing rope to it and abbed to the bottom. Despite previously leaning back and putting as much weight as possible on the system there was an "exciting" freefall sensation as I dropped probably 3 metres+ when I first left the ledge. I weighed about 67kg.

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In reply to deepsoup:

> Do you know any sea cliff climbing heroes (or cavers) with a 120m static (semi-static, LSK, whatever you want to call it) rope they could lend you?  The rope stretch would probably still be quite substantial, but significantly more manageable I would think. <

Possibly some people here, including me, may be forgetting that if there's a big joining knot stopping the rope from the belayer passing through the top krab then there is only a max of 60m of rope to stretch above the climber. In fact if one had a 120m rope it might be worth tying a big knot in the middle to halve the potential stretch.

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In reply to oldie:

That was a daft post on my part, past my bedtime. Once the knot comes against the top krab the climber is back on the ground and it will obviously be the stretch in all the rope between belayer and climber that will be involved.

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 smithg 21 Oct 2020
In reply to Toerag:

Nah, it’s not that bad, just feels like you’re getting a little upwards assistance

It’s less unpleasant than decking out.

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 JimR 21 Oct 2020
In reply to JStearn:

Anyone who has fallen off initial moves when seconding a long pitch on two halves will understand the amount of stretch on two halves in parallel never mind in series 😀 

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In reply to GrahamD:

> Rope stretch isn't the only potential problem.  120m of rope is going to be heavy !

Only what a team would take up to the route anyway (a 60m rope each)

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In reply to JStearn:

Not going to be a problem but keep the climber on tight for the first few moves.

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 GrahamD 21 Oct 2020
In reply to DubyaJamesDubya:

> Only what a team would take up to the route anyway (a 60m rope each)

That's true, although 60m pitches are rare.  I was thinking more about the manhandling of the ropes for rigging.

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 Jamie Wakeham 21 Oct 2020
In reply to JStearn:

If these are indoor climbers having their first go at ice, they are going to fall off.  The idea of novices flailing about with pointy things whilst they drop many metres of rope stretch is not a good one.

If I was going to rig this, I'd get hold of a pair of 50m (semi)static ropes.  I'd abseil 45m down the pitch, place a huge nest of ice screws, equalise them all, and then back this up to the bomber tree anchors with the two abseil ropes.

I'd then bottom rope the remaining 15m pitch with a 60m rope, doubled over.  This reduces their stretch in a fall, and also gives you redundancy for when they stick an axe through one of the strands.

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In reply to GrahamD:

> That's true, although 60m pitches are rare.  I was thinking more about the manhandling of the ropes for rigging.

I assumed the guy would lead it on a pair then set the ropes at the top and ab off. I guess that may not be the case. Either way, if he's going to top rope the climb he will need that amount of rope.

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In reply to JStearn:

Nutty suggestion for fun only. If one had to minimize rope stretch it might be possible to place a screw at, say, 15m and use a progress capture method to limit any early stretch caused by a hanging climber to a maximum of 15m of rope below the anchor. Certainly not appropriate for a novice, who would have to sort things out if the setup jammed, or when they couldn't be lowered back down if they couldn't reach the intermediate anchor. 
 I've little experience of these things but I've just tried in minature with a French prussik from the "screw" on the "climber's" rope side plus the slot of a belay tube to prevent the prusik gripping as the rope is taken in above the climber. It worked, but I can't envision if any problems would arise with 120m of rope etc.
 

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 Cobra_Head 23 Oct 2020
In reply to Toerag:

> That would be a supremely unpleasant experience for the climber.


Not as bad as hitting the floor, surely?

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