/ rope for rjukan
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.
Get 2x 60 metre half ropes.
dont use half ropes (personal preference)
oh well, enjoy a lot of abseiling and rope hassle then.
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 !
''what complications can i experience on ICE that would be simpler with half ropes ? ''
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.
> 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
If you don't want the answer why ask the question?
Also I have never heard of someone cutting their rope with an axe or crampon, just the odd burr on the sheath.
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.
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.
I've got a mammut one I think. I know it's orange and is 60 metres long. 8.5mil I think.
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.
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.
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?
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.
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.
and when i say i understand the consequences i mean i understand the consequences-nobody will come up with anything i haven,t considered.
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".
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
> 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.
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.
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.
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.
Iím convinced you donít know what youíre on about.
If itís good enough for him itís good enough for me but like he says there are more questions.
you have been doing your home work will i,m impressed 8/10 for good work !
No, they recommend half ropes because it generates 200/300% more sales ;-)
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