Using thin-ish 70m single rope as halfrope?

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immortality
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Using thin-ish 70m single rope as halfrope?

Postby immortality » Thu May 09, 2013 4:21 pm

The thought popped into my mind. If you're doing multi-pitch climbs with pitches no longer than say 30m, that would preferably require half ropes, but you only have a single 70m, could one just tie in both ends and use the 1 single rope as an effective half rope setup?

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brianweaver
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Re: Using thin-ish 70m single rope as halfrope?

Postby brianweaver » Thu May 09, 2013 4:37 pm

You can do this, however, it makes it hard to differential between left and right ropes, ie: it is easier to to make a mess of your clips and create extra drag in the process.

I have done this before for short climbs in the Kloofs but it often creates a lot of problems. One of which is bailing off a multipitch, you double the number of abseils to get to the ground. If you nick the one side of your single, your entire rope will be compromised. A lot of times you can link pitches when you have 60m of rope but obviously can't with a single 70m rope.
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immortality
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Re: Using thin-ish 70m single rope as halfrope?

Postby immortality » Fri May 10, 2013 10:22 am

Shot for the tip. It maketh sense.. Still a possibility though if needs be.

zabullet
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Re: Using thin-ish 70m single rope as halfrope?

Postby zabullet » Fri May 10, 2013 10:59 am

With a very quick look on the internet I can't find any reference material, but I seem to remember that you should *not* do it for the following reason.

Essentially all the ropes are designed to carefully balance stretch and impact force. The longer it takes to slow you down the less force the gear and your body will experience. The extreme of this is a static rope which largely stops you instantly, essentially breaking you in half as you upper body snaps over.

Now this is the part that I stand to be corrected on, but take an example to the extreme, tie 5 or 10 single ropes to you and take a fall, you'll slow down a lot faster; increasing your impact force. My understanding is that single, half and twin ropes carefully balance the equation given their specific uses.

There are ropes that are certified for all 3 uses e.g. http://www.mammut.ch/en/productDetail/2 ... enity.html

I'd say only use your rope as it is certified.....that being said I've used a single rope as a half....and it all becomes largely irrelevant if you don't fall ;)

zb.

immortality
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Re: Using thin-ish 70m single rope as halfrope?

Postby immortality » Fri May 10, 2013 11:39 am

Ja that does make sense.

Just randomly comparing The Mammut Genesis 8.5mm(half) and the Serenity 8.9mm(single). Their impact forces are 5.6kN and 8.9kN respectively. Quite a difference, so it would be a bad idea then.

Thanks guys.

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lelikegogga
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Re: Using thin-ish 70m single rope as halfrope?

Postby lelikegogga » Fri May 10, 2013 12:18 pm

I think the impact force thing only becomes a problem when you clip both ropes through the same point(s). Doing this will also effectively eliminating the very reason (in this case reducing rope drag) for using two ropes.

Note that impact force also becomes a factor on routes with sketchy/marginal/micro gear. But a whole other story, and I'm no expert. I suspect you can lower the impact force better with dynamic-ninja-belaying-tactics than with just using a different rope.
That said, the difference between 5.6kN and 8.9kN is nogals significant.

zabullet
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Re: Using thin-ish 70m single rope as halfrope?

Postby zabullet » Fri May 10, 2013 6:23 pm

lelikegogga wrote:I think the impact force thing only becomes a problem when you clip both ropes through the same point(s).


Probably......but not unheard of when climbing on half ropes.

zb.

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mountainmailorder
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Re: Using thin-ish 70m single rope as halfrope?

Postby mountainmailorder » Fri May 10, 2013 8:03 pm

I often climb shorter trad pitches (< 30m) with one half rope, folded in two. works just fine.
advantages:
1/ less rope to carry up to the climb.
2/ less rope to pull through. at the end of the pitch you save yourself from pulling the extra 30m+. that saves a lot of time and energy.

minor disadvantages:
1/ keeping red and red apart. but a seasoned trad climber will look more at which rope runs left and right and the color matters less.
2/ if you are abseiling in or out then you are limited to 30m.

this thing does tend to annoy my belayer more than me because i keep yelling "clipping red".

half and single ropes have very different fall factor tests. technically a single used as a half rope is 100% OK technically. some skinny single rope manufacturers e.g. Mammut and Beal explicitly promote their single as being a half rope too.

- Robert

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Re: Using thin-ish 70m single rope as halfrope?

Postby zabullet » Mon May 13, 2013 8:35 am

mountainmailorder wrote:technically a single used as a half rope is 100% OK technically.


This is where I think you you're wrong. Technically it isn't OK unless it carries the half and/or the twin markings.

mountainmailorder wrote:some skinny single rope manufacturers e.g. Mammut and Beal explicitly promote their single as being a half rope too.


The vast majority of their single ropes are *not* marketed as half or twin....I think for each brand they only have 1 that is marketed this way.

9.1mm Joker caries the single, half and twin designation (http://bealplanet.com/sport/anglais/corde-joker.php)

while the marginally thicker

9.4mm Stinger III caries only the single designation (http://bealplanet.com/sport/anglais/corde-stinger.php)

In fact the marketing on the Joker explicitly states "first thin rope on the market to meet the requirements for all three standards for dynamic ropes".

As I've stated I've happily climbed trad on 2 single ropes, but I'd be amiss to say that was the correct usage of the rope because it wasn't tested and certified for that use.

zb.

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Re: Using thin-ish 70m single rope as halfrope?

Postby Old Smelly » Tue May 14, 2013 10:21 am

Sometimes I think one can overdo the technicallity of these things...

You say that you shouldn't use two singles together when climbing double rope technique but using logic one then has to address two questions;

When they climb trad in the USA on a single rope is this any different to climbing double rope technique in SA with two singles? If it is what is the difference? the way they place their gear? The weather? The rock?

Surely when they fall onto trad gear on a single rope the impact force is the same as sport? or are they doing it all wrong? I doubt it as Black Diamond etc. are making the gear for them.

Ok so what about two singles used in a double rope system? I doubt that when you fall that you will load both ropes equally. Nine times out of ten you will load one rope & the other will not become involved unless the gear on the first one pulls...

What am I saying? Basically even on a double rope system most of the time when you fall it will behave exactly like a single rope system. So why would you use doubles then...because they can be lighter but give two ropes to cut instead of one, you can arrange them to give less drag, bring up 2 seconds & abseil double the distance...

Sorry I think the impact force thing is almost entirely a red herring...
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Re: Using thin-ish 70m single rope as halfrope?

Postby Nic Le Maitre » Tue May 14, 2013 10:44 am

Here are the actual standards: http://bealplanet.com/sport/anglais/savoir.php
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Old Smelly
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Re: Using thin-ish 70m single rope as halfrope?

Postby Old Smelly » Tue May 14, 2013 12:21 pm

No question about the required standards for rope manufacturers or the fact that half ropes are specialised, that's logical & to be expected. Half ropes do the job they are designed for admirably.

The question was whether singles could be used instead of half ropes...& I do not think that the manufacturers specs or the UIAA standards contest this. I liked the explanation about the static rope & how it would break you in half...the best explanation about the impact force...better for your anchors if you lower the impact force...

Still beyond all that & back to reality...do you fall onto both ropes or one?

What happens in USA, do they experience less gravity? Single rope trad is well accepted there...you don't see climbers wailing about the impact forces...

The same reality for everyone is that most of the time you fall onto one rope...whether it is a single or a half rope...

So notwithstanding that half ropes are better designed for double rope climbing...I still contend that one can climb safely on two singles, with no real difference apart from the fact that you may load the anchor with a higher instantaneous force...the real advantages are as listed above...longer abseils etc.
Really, its not that bad...I think it's my shoes...

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Re: Using thin-ish 70m single rope as halfrope?

Postby Nic Le Maitre » Tue May 14, 2013 12:58 pm

In the US, many of the routes are straight enough that two ropes are not required to reduce rope drag and therefore you can use just one rope easily. However, half ropes are not rated (or recommended) for use on their own and so people then use a single rope.

Single ropes will produce higher impact forces on both you and on the gear that you are falling on to. These forces are never high enough to injure you or to break the gear you are climbing, they might be enough to pull out a marginal piece that might have held had you used a double rope system. Using two single ropes will increase the impact forces further.

It is also worth noting that "static rope" is a misnomer, it is more correctly called "low stretch". Low stretch rope stretches about 10% of its length while dymanic (or high stretch) rope stretches about 30-40% of its length. Only cables and (some) webbings are truly static.

For a long time I used Beal Jokers as my trad, sport and ice ropes. They were ok for everything, not good at anything. Too fast wearing for a sport rope, too heavy for trad and ice. Jack of all trades, master of none. If you can afford it, get dedicated ropes for each activity.
Happy climbing
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Old Smelly
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Re: Using thin-ish 70m single rope as halfrope?

Postby Old Smelly » Tue May 14, 2013 1:54 pm

Nicely put Nic!

Still want to know how the two singles will put more impact force on to you then one in real life (i.e. where the two ropes are not clipped into 2 pieces of gear that are at the same height & distance from the climber - a scenario that could happen if you stuck two pieces of gear in the same rail but is otherwise unlikely).

I am not disagreeing with you on terms of there being a chance of greater impact force, just observing that it is very unlikely for this to be meaningful for most trad climbers on a day to day basis.
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