/ rope for rjukan

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jas wood - on 07 Dec 2006
chaps,
50 mtr single or 70 mtr single ?
please don,t say 60 as cannot justify another rope (to the missus!)
understand some routes involve abseil decents.
jas
Geoffrey Michaels on 07 Dec 2006 - 88-105-7-185.dynamic.dsl.as9105.com
In reply to jas wood:

Get 2x 60 metre half ropes.
Oli - on 07 Dec 2006
In reply to jas wood: I would take doubles if you have them, but if not 70m single as you can ab further with it doubled.
jas wood - on 07 Dec 2006
In reply to Donald M:
dont use half ropes (personal preference)
jas
Geoffrey Michaels on 07 Dec 2006 - 88-105-7-185.dynamic.dsl.as9105.com
In reply to jas wood:

oh well, enjoy a lot of abseiling and rope hassle then.
TWINKLETOES - on 07 Dec 2006
In reply to jas wood: Time to change your preference then. 1/2 its got to be, it gives you a lot more flexibility :o)
stone monkey - on 07 Dec 2006
In reply to jas wood: What happens when your second chops through your one and only rope...?

Use doubles.
jas wood - on 07 Dec 2006
In reply to jas wood:
you use halves i do not and know and understand the consequences.
i carry a 70 mtr lenght of cord which i can use for ab if i need to and what complications can i experience on ICE that would be simpler with half ropes ?
wasn,t starting a debate of single versus halves as it,s been done to death !
jas
David Hooper - on 07 Dec 2006
In reply to jas wood: For ice - 2 x 60m skinnys (less shock load on screws etc if you fall & have done a lot of multi -abs at Rjukan) BUT if you only want to climb on 1 rope then surely it has to be a 70m - good for longer sports as well apparently.
mick taylor - on 08 Dec 2006
In reply to jas wood:

''what complications can i experience on ICE that would be simpler with half ropes ? ''

Howdy jas

Do you want a list?

My mate managed to slice clean through one of our double ropes - total fluke - i just flicked the rope at the same time as he swung his pick.

I now use a 60 m and a 58.5 m rope.

Ta, Mick
styman on 08 Dec 2006 - host81-159-237-44.range81-159.btcentralplus.com
In reply to jas wood:
> (In reply to jas wood)
> you use halves i do not and know and understand the consequences.

I don't think that you understand the consequences that well at all. The impact force transmitted to your gear by a single rope is much higher than with a half rope and especially more so than with a skinny half rope like an iceline. If your gear is a less than perfect ice screw then you want to put as less force on it as possible and using one single rope is not the way to do it. Then as already pointed out you can put an axe or crampon through your rope and you have no back up and as for uncoiling 70m of ab cord at the top of every route let alone having to carry it with you in the first place, what a total faff.

Climbing ice on a single rope is dumb. No debate

Geoffrey Michaels on 08 Dec 2006 - 84-12-78-38.dyn.gotadsl.co.uk
In reply to jas wood:

If you don't want the answer why ask the question?
Will1 - on 08 Dec 2006
In reply to jas wood: Depends which routes you're climbing, generally for Rjukan a 50m single will be fine if you are using a 55m cord for abs. You'll just have to extend the odd runner a bit more than usual in the odd situation.
Will1 - on 08 Dec 2006
In reply to styman: Seem to remember this from a different thread. Impact forces for a single rope are tested with an 80kg load, halves are tested with a 55kg load, hence the difference in impact force presented by manufacturers. What would be the impact force of a half rope tested with 80kg? I'll hazard a guess that it'll be about the same as a single. Of course the ropes are used differently and this is represented by the test. There are ways to reduce the impact force on protection using Screamers or placing two pieces, one above the other in ice, and equalizing them. Now consider that a well placed screw in good ice will hold at least 10KN and a 20m factor 2 fall will generate 9KN. Basically single ropes are not inaproprite for ice climbing.
Also I have never heard of someone cutting their rope with an axe or crampon, just the odd burr on the sheath.
Mark L on 08 Dec 2006 - tritium.st-and.ac.uk [wwwcache.st-and.ac.uk]
In reply to Donald M:

> If you don't want the answer why ask the question?

Perhaps he wanted the answer to his question rather than what you thought it should be. He asked whether a 50 or 70m single rope would be best, he even explicitly stated that he wasn't considering any other options.

Geoffrey Michaels on 08 Dec 2006 - 84-12-78-38.dyn.gotadsl.co.uk
In reply to Mark L:

Ok 70 metre one then.

I hear that out of the Austin Allegro or the Austin Princess, not considering any other options obviously, the Princess would be the best if you were entering the Paris-Dakar Rally.
styman on 08 Dec 2006 - host81-159-237-44.range81-159.btcentralplus.com
In reply to Will1: Sorry Will but you don't know what you are talking about. A half rope will always transmit less force as it is thinner and will therefore stretch more to absorb more of the energy of a fall. The impact force of an 80kg weight on a half rope would be lower than on a single rope but you'd only get a fraction of the number of recorded falls. As for putting two ices screws together and equalising them, sounds great but have you ever tried it on vertical ice whilst hanging off one tool? As for screamers, yes they definately work, but will be alot better on a half rope. The whole point of using a screamer is to reduce impact forces so if that is the aim you should be using half ropes not singles.
TRip - on 08 Dec 2006
In reply to Donald M: donald how skinny are oyur skinny ropes?
Geoffrey Michaels on 08 Dec 2006 - 84-12-78-38.dyn.gotadsl.co.uk
In reply to Tom Ripley:

I've got a mammut one I think. I know it's orange and is 60 metres long. 8.5mil I think.
mick taylor - on 08 Dec 2006
In reply to styman:

Howdy styman

Spot on

Ta, Mick
ads.ukclimbing.com
Will1 - on 08 Dec 2006
In reply to styman: I just copid this from a thread on rockclimbing.com ;
I just finished a series of drops on half ropes with 80kg at the request of Will Gadd.

Rope A. 80kg-7.35kN, 55kg-5.39kN, published with 55kg-4.85kN
Rope B. 80kg-8.15kN, 55kg-6.23kN, published with 55kg-6.3kN
Rope C. 80kg-8.23kN, 55kg-6.25kN, published with 55kg-6.5kN
Rope D. 80kg-9.22kN, 55kg-5.88kN, published with 55kg-6.1kN

These drops were conducted without the regulation conditioning but complied with all other requirements and procedures. Relative humidity was 42%, temperature was 20ļC for 48 hours. I also listed the published numbers from each manufacturer; I used ropes from 3 different ones.

http://www.rockclimbing.com/cgi-bin/forum/gforum.cgi?post=1394069;sb=post_latest_reply;so=ASC;forum_...

And again from Jim

It's not as simple as it sounds. A skinny rope does not generally stretch more. The construction of a skinny rope is different than a fat one. Because a fat rope has so much more mass than a skinny one it has to be designed differently so it won't give too high an impact. Skinny ropes have the opposite challenge, more or less. Half ropes are drop tested with 55kg but are tested for static elongation with 80kg so they still have to offer a high resistance per mass.
Manufacturers do all kinds of things to manipulate the properties of the rope so it's not just a matter of diameter or mass, although that does come into play.
styman on 08 Dec 2006 - host81-159-237-44.range81-159.btcentralplus.com
In reply to Will1: Interesting figures although the poster hasn't concluded why they get the high figures. I would have thought it would be because the skinny rope would 'bottom out'under the force of an 80kg factor 2 fall and therefore create a high force. The replication of an 80kg factor 2 lead fall is pretty unlikely in the world outside of a test lab though and it doesn't change the fact that a falling climber will create less impact on a half rope than a single rope. A skinny rope does 'generally' stretch more than a fatter rope.
Will1 - on 08 Dec 2006
In reply to Will1: I will re do my guess and say that it's not actually the same, just substantially higher force that that quoted for a 55KG load. So I was wrong. I haven't actually seen any data on this before. This as you say unlikely outside the lab for sure. and personel experience tells me that half ropes do stretch more that single ropes.
Mark L on 08 Dec 2006 - tritium.st-and.ac.uk [woodstock.st-and.ac.uk]
In reply to styman:
> A half rope will always transmit less force as it is thinner and will therefore stretch more to absorb more of the energy of a fall.

A stretchy rope does not 'absorb energy'; it reduces peak force. The energy in both cases will be the same.

Incidently, there seems to be an assumption that a screw might fail due to a high impact force, and that more sustained but lower forces (i.e. from a stretchy rope) will not produce the same effect. Does anyone know how true this is?
Will1 - on 08 Dec 2006
In reply to styman: Having checked the Mammut data for single ropes these figures are actually higher than those of a new single rope. Are you surmising that the ropes have reached there elastic limit in these tests?
However I don't still don't think that a single rope is inappropriate for ice climbing, at least not unless it is WI5 where placing gear becomes a real strain and the route may not be straight up.
styman on 08 Dec 2006 - host81-159-237-44.range81-159.btcentralplus.com
In reply to Mark L: A stretchy rope does absorb energy and by doing so creates a lower peak force! If no energy was absorbed by the rope then all impact forces for a given weight would be the same regardless of the rope used!
Mark L on 08 Dec 2006 - tritium.st-and.ac.uk [wwwcache.st-and.ac.uk]
In reply to styman:

Sorry, that was meant to read "A stretchy rope does not 'absorb more energy'".

In each case, the kinetic energy of the falling climber is equal, thus both ropes 'absorb' the same amount of energy. If the rope is stretchy, the force is lower, but over a greater period. If the rope is low stretch, the force is higher, but for a shorter time. In both cases the work done is the same.
jas wood - on 08 Dec 2006
In reply to styman: your opinion and not mine.
and when i say i understand the consequences i mean i understand the consequences-nobody will come up with anything i haven,t considered.

jas wood - on 08 Dec 2006
In reply to Donald M: "the question" as you put it was 50 single or 70 single! no mention of half ropes.
jas
jas wood - on 08 Dec 2006
In reply to mick taylor:
re-''what complications can i experience on ICE that would be simpler with half ropes ? ''
the reply was maybe not worded correctly !
it was a reply meant for the chap mentioning "rope hassle" and not the senario,s like you mentioned "severed rope".
jas

Will1 - on 08 Dec 2006
In reply to jas wood: Think they mean the extra coiling and pulling through that a 70m will involved.
Anonymous on 08 Dec 2006 - cpc4-midd5-0-0-cust892.midd.cable.ntl.com
In reply to Will1: coiling on route or in sac ?
on route-the coiling in my opinion/limited experience(with halves) is worse than a single.
in the sac- yes it is a big old lump of rope BUT one of us stows rack one has rope - usually me that gets the cack end of the stick with the rope!
also with complex pitches it,s quite easy to use the single doubled as a 35 mtr half (if thats the right word!)

jas @ brothers
Will1 - on 08 Dec 2006
In reply to Anonymous: Think it's more the length of a 70 as opposed to a 60 or 50. If your pitch is 25m, or your moving round from climb to climb it gets a bit tedious thatís all. 50m is fine for Rjukan.
styman on 09 Dec 2006 - host81-158-145-183.range81-158.btcentralplus.com
In reply to Mark L:
> (In reply to styman)
>
> Sorry, that was meant to read "A stretchy rope does not 'absorb more energy'".
>
> In each case, the kinetic energy of the falling climber is equal, thus both ropes 'absorb' the same amount of energy. If the rope is stretchy, the force is lower, but over a greater period. If the rope is low stretch, the force is higher, but for a shorter time. In both cases the work done is the same.

Not quite. The work done is not the same, the lower force over a longer period reduces the impact reaching the protection. The single rope stops you quicker with a higher impact force due to less stretch. The reason the half rope has a lower impact for longer is because the rope is stretching for a longer period. A karabiner can hold weight to its limit indefinately so low impact over a long period creates no problems. As soon as you take it over its limit for just a second it may well break so trying to say 'in both cases the work done is the same makes no sense whatsoever.
Will1 - on 09 Dec 2006
In reply to styman: You seem very knowledgeable for a bloke who didn't know that single and half ropes are tested with different loads?
styman on 09 Dec 2006 - host81-158-145-183.range81-158.btcentralplus.com
In reply to Will1: Where have I said that I didn't know the weights used in the drop tests?
Will1 - on 09 Dec 2006
In reply to styman:
Ok, you didnít actually say that but you left that impression. When I said that reason the figures for impact force were different was because they were tested with different weights you said I didnít know what I was talking about. You also said that the a half rope tested with 80kg would produce a lower impact force, which is wrong.
Mark L on 10 Dec 2006 - bhpc-mel2.st-and.ac.uk
In reply to styman:

> As soon as you take it over its limit for just a second it may well break so trying to say 'in both cases the work done is the same makes no sense whatsoever.

Neither does that post! You do understand the difference between work and force don't you? Obviously high force is bad and snaps things, which is why ropes stretch. However, a stretchy and non stretchy rope still need to do the same amount of work to stop a falling climber even if one does have a much higher force. Look up 'conservation of energy' if you need more info.

Will1 - on 10 Dec 2006
In reply to styman: Half ropes stretch more because of the way they are designed, they also stretch more easily not reducing the speed of a climber as quickly and not absorbing the energy from a fall as quickly. This means that if you fell on a half rope you would fall further and faster than on a single rope. The results above show that when the ropes stopped you the peak force would still be similar to that of a single rope.
In practice however half should be used in pairs (except in some alpine situations) and the second rope in the pair would come into play as you fell reducing the impact forces on each piece of gear.
Like mark says both ropes still have to stop a climber falling the same distance at the same speed, so in both cases the work done is the same.

Ďdoesn't change the fact that a falling climber will create less impact on a half rope than a single rope.í This statement is wrong, see above.
ĎThe impact force transmitted to your gear by a single rope is much higher than with a half rope and especially more so than with a skinny half rope like an icelineí So is this one.
ĎA half rope will always transmit less force as it is thinner and will therefore stretch more to absorb more of the energy of a fallí And this, it has to absorb the same amount of energy.
ĎTransmit forceí????

Iím convinced you donít know what youíre on about.
styman on 10 Dec 2006 - host217-42-141-225.range217-42.btcentralplus.com
In reply to Will1: OK Will you must be right. All rope manufacturers recommend single ropes for ice climbing as they work exactly the same as half ropes. Right?
ads.ukclimbing.com
Will1 - on 10 Dec 2006
In reply to styman: Apologies Styman for being so rude in my earlier post. Having been flamed by you I have been looking for info to back up my assumption and found this, see below;

http://gravsports.blogspot.com/2006/11/single-and-half-rope-impact-forces_30.html

If itís good enough for him itís good enough for me but like he says there are more questions.
Anonymous on 11 Dec 2006 - 193.128.75.178 whois?
In reply to Will1:
you have been doing your home work will i,m impressed 8/10 for good work !
jas@work
Robbie H - on 02 Feb 2007
In reply to styman:

No, they recommend half ropes because it generates 200/300% more sales ;-)
BorisB on 02 Feb 2007 -
In reply to jas wood: Most def at least a 60 for gausta, dont worry about chopping through it, my mate put an axe clen through his and it survived.

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