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asdf
Feb 15, 2007, 5:57 AM
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Anyone know if there is any issue with using a 10.5 (single rope) and a 9 (double rope) as a pair alternating clipping of ropes? Is there an issue with the differing dynamic character of the ropes if they are not clipped into the same protection?
Reason for post is that I have a 10.5 for cragging and will be doing some multipitch this summer and want to have double ropes (in case of self rescue/rapping needs). If I can get away with buying just one 9mm rope this summer than I do not mind carrying the extra weight of the 10.5. If there is a safety issue I will obviously buy the pair of 1/2 ropes.
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chalkfree
Feb 15, 2007, 6:10 AM
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odds are you'll never fall in a fashion to weight both of them at once, which is the only situation where the less strechy rope could cause problems.
I'd do it without a second thought.
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vegastradguy
Feb 15, 2007, 6:35 AM
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the short answer is- no, you cannot use them as doubles.
the longer answer is- doubles are designed to be clipped separately, but between you and the first piece on a multipitch, they are one rope. that is, if you fall before you clip your first piece, you're falling on both ropes- and double ropes are rated for this sort of fall. fall on a 10.5 and a 9 and you're increasing the impact force on the system drastically. so, in theory, the way you clip double ropes would tempt you to use a single with a skinny double, the truth is that the overall safety of the system is compromised if you are using a single rope in a double system.
however, if you want to get a 9mm double, it'll do as a nice trail line and a lead line in a pinch- as good a backup as you can have without actually having a double rope system.
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kevinheiss
Feb 15, 2007, 12:29 PM
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As everyone else said, NO would be the anwser.
If you want to carry a second rope with you, do so but just have it follow you from behind but don't clip it in.
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lemon_boy
Feb 15, 2007, 5:30 PM
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man, you kids sure aren't creative.
you can indeed use them as doubles, even on multi-pitch routes. you don't seriously think we didn't use them back before the new age sensitive skinny ropes were developed do you?
on multi-pitch, or other similar situations, have the belayer feed out quite a bit of extra slack rope on the fat rope. clip your skinny rope into the first piece. the reason for this is, if you pitch before the first piece you will be hucking straight onto the anchor. if you have a bunch of extra slack in the fat rope, it won't come tight and increase the load on the anchor. the skinny rope should be effectively less stiff than the fat rope (in general, there are exceptions to this), and will hopefully be the lesser of 2 evilson your anchor.
now using them as twins, on the other hand. no.
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jp_sucks
Feb 15, 2007, 5:36 PM
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Or you can get an 8mm static line as your second rope and leave it in your pack until needed for the raps.
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gimpster93101
Feb 15, 2007, 5:49 PM
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I was just in Red Rocks this weekend and somebody mentioned that they liked to pack along a 60m piece of 8mm static rope while multi-pitching, purely for use as a 2nd rope on double rope raps.
Is this legit? Can I tie my 9.8mm dynamic lead rope to a 8mm static line and set up a safe double rope rap in a multi-pitch situation?
If so, why doesn't everybody do this? It seems like it would be way cheaper than buying two dynamic ropes...
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lemon_boy
Feb 15, 2007, 6:04 PM
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i don't like bringing the static along because it isn't nearly as versatile. if you run into a situation where you want to lead on doubles (red rocks, gunks, desert towers, and eldo come to mind) a static isn't going to be much help. also, if something happens to your lead rope (this has happened to me twice), it is nice to have a second rope that you can lead on. this is also why i don't like twins, there isn't enough margin to realistically keep going if you're planning on leading hard on a single twin.
in terms of economics, i would rather spend a little more up front for something that i am going to use infinitely more.
not saying statics don't have their place, just not as useful for free climbing.
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jeremy11
Feb 15, 2007, 6:30 PM
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I've used 2 10.2s as doubles for single pitch. a factor 2 on both ropes is of course not possible, you'd hit the ground   . for multipitch, I'd go on a case-by case for the pitch if you need to feed out slack on the bigger rope before the first clip. that said, I prefer to lead on a single when possible/practical. there are other ways of getting the second rope to the top
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unrooted
Feb 15, 2007, 6:39 PM
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I borrowed my roommates 8mil while I was in the wind rivers this summer, it was great, it fits easily into a small pack, and rapping was fine, it can be a bitch to pull though because it is so damn small.
I will definately try to do the same everytime I go somewhere with a big approach, light is right.
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bandycoot
Feb 15, 2007, 6:57 PM
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gimpster93101 wrote: I was just in Red Rocks this weekend and somebody mentioned that they liked to pack along a 60m piece of 8mm static rope while multi-pitching, purely for use as a 2nd rope on double rope raps. Is this legit? Can I tie my 9.8mm dynamic lead rope to a 8mm static line and set up a safe double rope rap in a multi-pitch situation? If so, why doesn't everybody do this? It seems like it would be way cheaper than buying two dynamic ropes...
Everybody doesn't do this because it is situation dependent. I do it often as do many people I know. It isn't necessarily cheaper because I think that a 60 8mm static line (at least from beal at REI) runs about $110. From what I've read, you can tie two different diameter ropes together with the overhand knot (EDK) for rapelling. Leave long tails. I've never had a problem with this. Keep the knot on the anchor so you have to pull the thin line if there is a large difference in friction/size between ropes.
Josh
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pastprime
Feb 15, 2007, 6:58 PM
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Most of the ropes sold and UIAA certified for use as double ropes are 9mm.
When you are alternating clips you are only on one rope at a time, so it doesn't matter if the dynamic characteristics are different.
If both ropes are clipped in parallel, as twin ropes, there are some possible scenes, where one rope is stretching more than the other, that can create rubbing of the sheaths, so different sized ropes shouldn't be used that way.
Using two different sized ropes as doubles has been very common in Europe for decades.
If you fall on two single rated ropes, the impact force does get higher, but does not go up to dangerous levels. You would think it would double, but it doesn't. The reason is that the impact force of a rope is not a linear curve. The early part of the curve is softer than the later part, and when using two ropes you are doubling the forces from a softer part of the curve.
Think about it: If it weren't this way, it would not be safe for a 90 pound climber to use a rope designed to be ok for a 180 pound climber.
Don't have time to look for a link now, but I would ask those who want to argue to not just give and opinion, because this is one of those questions that comes up over and over and the answer is always the same.
(This post was edited by pastprime on Feb 15, 2007, 7:20 PM)
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brent_e
Feb 15, 2007, 7:08 PM
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vegastradguy wrote: the short answer is- no, you cannot use them as doubles. the longer answer is- doubles are designed to be clipped separately, but between you and the first piece on a multipitch, they are one rope. that is, if you fall before you clip your first piece, you're falling on both ropes- and double ropes are rated for this sort of fall. fall on a 10.5 and a 9 and you're increasing the impact force on the system drastically. so, in theory, the way you clip double ropes would tempt you to use a single with a skinny double, the truth is that the overall safety of the system is compromised if you are using a single rope in a double system. however, if you want to get a 9mm double, it'll do as a nice trail line and a lead line in a pinch- as good a backup as you can have without actually having a double rope system.
Hey John,
the high fall factor on a multipitch belay can be avoided by only using 1 rope until a piece is clipped.
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Dillbag
Feb 15, 2007, 7:16 PM
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pastprime wrote: I don't know where the naysayers in some of the above posts are coming from...When you are alternating clips you are only on one rope at a time, so it doesn't matter if the dynamic characteristics are different.
The "naysayers" were pointing out a specific scenario of leaving the belay on a multi-pitch climb and falling prior to placing any gear... In this situation the impact force would be higher on the belay due to the "beefier" rope and could have potentially disastrous consequences.
As has been pointed out several times, this scenario can be mitigated by paying out enough slack that the "beefy" rope would not be weighted...
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reno
Feb 16, 2007, 12:39 AM
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Simplify:
If you only need the rope for double rope raps, then climb on the 10.5 single, and coil/carry the other.
I wouldn't use the two different ropes as doubles like you mention. Just borrowing trouble at that point.
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vegastradguy
Feb 16, 2007, 2:55 AM
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brent_e wrote: vegastradguy wrote: the short answer is- no, you cannot use them as doubles. the longer answer is- doubles are designed to be clipped separately, but between you and the first piece on a multipitch, they are one rope. that is, if you fall before you clip your first piece, you're falling on both ropes- and double ropes are rated for this sort of fall. fall on a 10.5 and a 9 and you're increasing the impact force on the system drastically. so, in theory, the way you clip double ropes would tempt you to use a single with a skinny double, the truth is that the overall safety of the system is compromised if you are using a single rope in a double system. however, if you want to get a 9mm double, it'll do as a nice trail line and a lead line in a pinch- as good a backup as you can have without actually having a double rope system. Hey John, the high fall factor on a multipitch belay can be avoided by only using 1 rope until a piece is clipped.
sure it can- of course this requires the party to be aware of this fact on every single pitch and do something special at the start of every pitch in order to avoid the danger. this seems like a huge waste of time, not to mention risky if you find yourself having to do it in the dark, in the rain, when you've bonked, or are injured, etc, etc....
is it unrealistic to do it that way- no. is it too much work for too little gain- yes.
just trail a rope- why even bother with using it as a double?
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phillygoat
Feb 16, 2007, 3:18 AM
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Sterlingjim wrote in another thread:
In reply to: I have to confess a pet peeve of mine. Officially speaking double ropes do not exist. There are half ropes and twin ropes. The definitions and functions of each are different. So when talking about double ropes it is important to understand which type is being discussed.
Although I haven't had a use for them yet, the subject interests me because, obviously, it's climbing related. But I must say it's confusing to follow due to the fact that these terms (twin, double, half) are frequently used interchangeably on this site. Personally, I'm inclined to take Jim's word on the matter...
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sterlingjim
Feb 16, 2007, 3:19 AM
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Dillbag wrote: The "naysayers" were pointing out a specific scenario of leaving the belay on a multi-pitch climb and falling prior to placing any gear... In this situation the impact force would be higher on the belay due to the "beefier" rope and could have potentially disastrous consequences.
You need to read this thread.
http://www.rockclimbing.com/...;;page=unread#unread
(This post was edited by sterlingjim on Feb 16, 2007, 3:21 AM)
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brent_e
Feb 16, 2007, 7:23 AM
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vegastradguy wrote: brent_e wrote: vegastradguy wrote: the short answer is- no, you cannot use them as doubles. the longer answer is- doubles are designed to be clipped separately, but between you and the first piece on a multipitch, they are one rope. that is, if you fall before you clip your first piece, you're falling on both ropes- and double ropes are rated for this sort of fall. fall on a 10.5 and a 9 and you're increasing the impact force on the system drastically. so, in theory, the way you clip double ropes would tempt you to use a single with a skinny double, the truth is that the overall safety of the system is compromised if you are using a single rope in a double system. however, if you want to get a 9mm double, it'll do as a nice trail line and a lead line in a pinch- as good a backup as you can have without actually having a double rope system. Hey John, the high fall factor on a multipitch belay can be avoided by only using 1 rope until a piece is clipped. sure it can- of course this requires the party to be aware of this fact on every single pitch and do something special at the start of every pitch in order to avoid the danger. this seems like a huge waste of time, not to mention risky if you find yourself having to do it in the dark, in the rain, when you've bonked, or are injured, etc, etc.... is it unrealistic to do it that way- no. is it too much work for too little gain- yes. just trail a rope- why even bother with using it as a double?
Understandable.
Thanks for discussing.
Brent
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scrapedape
Feb 16, 2007, 4:20 PM
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A much more relevant quote from sterlingjim, from the thread he linked. I have taken the liberty of quoting directly here, since I suspect many wouldn't bother to look at the thread he linked.
sterlingjim wrote: 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 20ºC for 48 hours. I also listed the published numbers from each manufacturer; I used ropes from 3 different ones.
It looks like half ropes give you roughly comparable impact forces to singles when tested in the single rope 80-kg drop test.
Given that, it appears to me that the risk of higher impact force on a multipitch isn't a real concern, and you can use a single in half-rope style if you want to.
The only possible caveat I can think of is that thicker ropes might slip through your belay device less than thinner ropes, increasing the braking force in that way. Not sure how much of an issue that is.
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moof
Feb 16, 2007, 5:57 PM
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You can go as light as a 7mm as a pure second rap line. Safe working load is 150 lbs, but as long as your'e doing a double rope rappel it'll never have your full weight. Also be careful with your choice of joining knots when the sizes are so different. I do a double EDK, but your mileage may vary.
I've even climbed with a guy who went as skinny as a 6mm, but used it only as a pull line, ie he always passed the fat rope through the rap rings and let the knot jam up against them. This added a lot of extra cluster as we had to pull the whole rig before starting the threading process. Also, not all rap rings are created equal...
Also be warned that skinny ropes like 6, 7, or 8mm really like to whip in the wind, and are much more perilous in places like red rocks where knobs and such abound. Probably best to stack the skinny one in a pack to feed out as you rap if there is worry about windage, but it can still turn into cluster during the pull.
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