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Abram
Trad climber
Golden, CO
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Aug 16, 2013 - 05:11pm PT
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In response to your question number one, no, 1/2 ropes cannot be used as twin ropes. I believe a company made one that works for both but I could be wrong... But the vast majority are labeled either 1/2 or twin for a reason.
With 1/2 ropes you'll be caught on only one rope, so they're less dynamic, and more like a single rope. If you clipped 1/2 ropes as twins, with both running through one piece so you're falling on both ropes simultaneously, you'd be generating a higher force than intended. Twin ropes are more dynamic, because they both catch your fall, rather than just one catching you.
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rockermike
Trad climber
Berkeley
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Aug 16, 2013 - 05:12pm PT
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Im no expert of dual rope systems, but I guess, under 8.0 you would want one of the special small rope belay/repel devices. That or wear gloves. ha
and no, not all 1/2 ropes are intended to be used as twins. Some are labled as usable for either system. I think the theory is that two 1/2 ropes would put too much stress on the pro. Then again, I{m not one to follow rules, so who am I to speak. I happen to have both one twin, and one 1/2. use them together at times. still alive. :)
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clockclimb
Trad climber
Orem, Utah
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Aug 16, 2013 - 11:01pm PT
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I'm also a bit of a rulebreaker. When I use 1/2 ropes I only clip one of them for the first few pieces of protection. As the fall factor reduces further up I go ahead and clip both of them unless I need to reduce rope drag.
Read the manufacturers recommendations for your autoblock device. The Black Diamond Guide covers 7.7mm - 11mm. The Reverso 4 covers 7.5mm - 11mm. I've never had trouble catching falls with 1/2 ropes.
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dgbryan
Mountain climber
Hong Kong
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Aug 16, 2013 - 11:39pm PT
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Can't really commnet on the ropes you mention.
It seems like quite a few of the Mammuts are rated for 1/2 and twin use, and I bought a set of Phoenix 8s back in June, used for 6 weeks in the Alps on a variety of rock.
These seemed very skinny when new, a lot less so after a couple of weeks. Seemed to knot (themselves) a little more easily than other ropes I have used. THey also show a little more superficial abrasion than I would have expected for the use.
We used them with a Mammut belay device, but I think they'd be fine with BD ATCs.
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rgold
Trad climber
Poughkeepsie, NY
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Aug 16, 2013 - 11:53pm PT
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I've been using half ropes almost exclusively for somewhere between 20 and 30 years.
The PMI is rated as both a twin and a half rope; the Beal and Bluewater are rated as half ropes only. The fact that the latter two ropes are not rated as half ropes probably means that their UIAA impact ratings when used together are too high, so you shouldn't use them as twins.
But there is no good reason to use half ropes as twins anyway, whether or not they are rated for such use. If you want twin ropes for full-length rappels and perhaps the extra cut protection, then buy twin ropes, which will be thinner and lighter. I think people who use halves as twins are afraid of using half ropes as they are intended to be used. If you are in that group, then don't get half ropes. If you aren't in that group, forget about using halves as twins.
There are a few considerations about diameter. Ropes in the 8.5mm range are workhorse ropes that should give excellent wear. Ropes in the 8mm range are lighter but will not last as long. Look at the percentage of the rope that is sheath; the higher sheath percentages will wear better in terms of abrasion. If you fall a lot, then the lower sheath percentages (higher core percentages) will last longer. I've also found that sub-8.5's seem more prone to tangling.
As for belaying and rappelling, there seem to be different experiences out there. My personal take is that you will have trouble holding a serious fall with a low-friction system on 8.1's. Others say no (but I don't really believe them). I'd recommend using an assisted locking device for all half ropes, and more strongly for 8.1's. The best such device for the slightly more intricate technique of half-rope belaying is the Climbing Technology Alpine Up.
Speaking of slightly more intricate technique, you lose a number of half rope advantages if the belayer doesn't properly manage the system. You need to be efficient at more or less simultaneously taking in one strand while paying out the other, for example. (An important trick: watch the ropes directly in front of you and you'll know immediately how to keep them adjusted. If you spend all your time looking up at the leader, you won't know what rope to pay out when the time comes and will probably end up paying out both, negating one of the important half rope advantages.)
My recommendation, especially for your first set, would be to get one of the choices in the 8.5mm range rather than the 8mm range, unless your goals require the lightest possible set-up and you are ok with a shorter rope lifetime.
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lubbockclimber
Trad climber
lubbock,tx
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Aug 17, 2013 - 02:32am PT
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The pmi halfs are good ropes really light and handle great
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Degaine
climber
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Aug 17, 2013 - 04:37am PT
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Rgold’s post provides a lot of good info.
Here’s my take/advice.
I’ve used doubles almost exclusively for multi-pitch routes for the last 14 years.
I highly recommend the Beal Cobra 8.6mm. I’m on my second or third pair, and the setup works great. At 8.6 each rope is light enough, and it wears well (as rgold stated “a workhorse” for this size diameter) and belays fine (in my experience) with an ATC guide or Reverso, with or without gloves.
I weigh around 62kg, and I’ve caught long and short falls just fine with the Cobras with partners who outweighed me by 20kg.
As stated, on trad gear best clip each rope individually (that’s what half ropes are rated for). It does take time to get used to, but belaying with half ropes is not that complicated. You do, as rgold states, need to be a very aware belayer, especially in terms of rope management. As I write that, I would add that you need to also be aware as a leader to avoid crisscrossing the ropes as you clip.
I’ve also climbed with 7.7 twin ropes, which means you can clip like climbing with a single rope. However, we both had Reversinos (don’t know if Petzl still makes them) and we had one pair of gloves for two for belaying the leader. Super light for the approach as each rope weighs next to nothing.
Other elements to add:
*I’ve found the dry treatment for the Cobra to work well and last long. I live in an area where I do a lot of glacier approaches. I also occasionally have been caught in a t-storm on rappel. Never had a problem with the ropes swelling.
*I’m okay with glacier walking or even doing easy to moderate high-mountain ridge climbing with a single strand of a double (half) rope setup. The Cobras work well for this. However this is not recommended by the mfctr.
I’ve also climbed a great deal with both the Beal Joker and Millet’s triple norm rated ropes. These are nice for alpine climbing / mountaineering as you have a single strand that can do anything. If memory serves these are in the 9.2 to 9.7mm range. These are great when you know that you either won’t have any rappels, or the rappels will be a short 15m to 20m along a ridgeline traverse.
Hope that helps.
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rgold
Trad climber
Poughkeepsie, NY
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Aug 17, 2013 - 09:11am PT
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The OP mentioned two half ropes that are not rated as twins as far as I can tell, so you can't compare the impact forces for those ropes, used as twins, with other single ropes. Presumably, if those forces were within the UIAA standards for twins, the ropes would also be rated as twins, and they are not. So I'd be cautious about generalizing about ropes that are rated for both uses to ropes that are not.
By the way, some conversations I've had with people in the rope industry suggest that the dual ratings did not occur by design as a response to perceived European usage, but rather more or less by accident as a byproduct of more effective design and manufacturing techniques. In other words, the manufacturers started testing their ropes according to standards they hadn't designed the ropes to meet and were pleasantly surprised to find the ropes met those standards as well. Perhaps someone with authoritative knowledge will have something to say about this.
The trouble with using half ropes as twins is you get something way heavier than a single rope with all the friction drawbacks that come with a single rope, so I still don't get why anyone would choose the worst of both worlds. When I use half ropes with a follower on each rope to form a quicker party of three, I still mostly use half rope technique. Sometimes, when traverses are involved, this would put one of the two followers in a bad position; in that case I'll either clip two ropes to one piece, usually with separate slings however, or else have whoever the leading second is clip the following second's rope to pieces after the leading second's rope is removed.
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Rock!...oopsie.
Trad climber
the pitch above you
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Aug 17, 2013 - 09:54am PT
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or else have whoever the leading second is clip the following second's rope to pieces after the leading second's rope is removed.
With my friends I find that when we do this team of three technique whoever the leading second is generally does this to the last guy just to make him carry all the gear, hehe.
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Degaine
climber
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Aug 17, 2013 - 10:06am PT
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The Europeans to which everyone is referring - or rather those who climb regularly in the Alps - frequently clip both strands of a double (half) rope setup because most of the multi-pitch routes they climb are bolted (nice shiny bolts or glue-ins).
Do not confuse bolted with sport routes (although there are plenty of those) as most climbs put up by the Remy brothers or Michel Piola were put up on lead and sometimes with frequent 6 to 7 meter runouts (hardly sport).
European climbers with any mountain experience will use double rope technique (clipping each strand individually) when on trad routes (pitons or placing gear).
My educated guess for testing as twins is as rgold stated: manufacturers looking for hard stats regarding how their customers were actually using the ropes in the field.
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Gilwad
climber
Frozen In Somewhere
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Aug 17, 2013 - 10:11am PT
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The half rope impact force tests are done with a completely different and much lighter weight test than the single rope fall tests. In real-world testing done at Sterling and other places rope diameter is not directly linked to impact forces. Half ropes tested with the same weight as single ropes often end up with higher impact forces. I don't weigh half as much while climbing on half ropes, but that's what the test weight is for half ropes.
You really don't want to clip two half ropes (or twins) into difference pieces and then both into one carabiner. In a fall the two strands will run at really different rates, which may lead to one rope cutting or seriously damaging the other. Either clip both into all pieces (twin) or independently.
I basically never climb on twin or half ropes, they are more of a pain and the ass and heavier, and I don't like the high impact forces twins generate (remember, different test...). I do use them in the winter alpine for "easy" terrain with long pitches that will require extensive rappelling, which is kinda rare terrain as most "easy" terrain is better done in short fast pitches or soloed.
Finally, remember that twins and halves generally stretch a LOT when loaded individually by a real human. I see people belaying seconds on individual strands and worry--until the second is about 30 feet off the deck he's going to smash hard if the full rope is out, they stretch like mad in general. If I have two seconds I tend to use two proper single ropes.
More info on rope tests here: http://willgadd.com/single-and-half-rope-impact-forces-data/
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