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blueeyedclimber


Aug 31, 2005, 6:01 AM
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Using singles as doubles?
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I would like to practice double rope technique, but do not have half(double) ropes. Aside from the extra weight, i can not think of any reason not to use them (for now). I hate trailing ropes and would like to practice this so that I can add it to my bag of tricks. Enlighten me, if I am missing something.

JOSH


vegastradguy


Aug 31, 2005, 6:10 AM
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just dont clip 'em to the same piece...i think thats about all that would be worrisome.

oh, and until you clip your first bomber piece on a pitch, make sure your belayer only has his hand on one of the lines, this will prevent you from being caught by two single lines in the event of a factor 2 fall...


onbelay_osu


Aug 31, 2005, 9:31 AM
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Re: Using singles as doubles? [In reply to]
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In reply to:
just dont clip 'em to the same piece...i think thats about all that would be worrisome.

oh, and until you clip your first bomber piece on a pitch, make sure your belayer only has his hand on one of the lines, this will prevent you from being caught by two single lines in the event of a factor 2 fall...

okay so when belaying a double line you are only belaying one line at a time??????


jt512


Aug 31, 2005, 9:37 AM
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In reply to:
just dont clip 'em to the same piece...i think thats about all that would be worrisome.

oh, and until you clip your first bomber piece on a pitch, make sure your belayer only has his hand on one of the lines, this will prevent you from being caught by two single lines in the event of a factor 2 fall...

Maybe clip one rope through the anchor.

To clarify VTG's point, you must avoid falling onto two singles clipped into the same piece, as the impact force will be dangerously high.

-Jay


microbarn


Aug 31, 2005, 10:06 AM
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In reply to:
just dont clip 'em to the same piece...i think thats about all that would be worrisome.

oh, and until you clip your first bomber piece on a pitch, make sure your belayer only has his hand on one of the lines, this will prevent you from being caught by two single lines in the event of a factor 2 fall...

okay so when belaying a double line you are only belaying one line at a time??????

no, you belay both. He is making a statement for an exception to the rule. Check out what I made bold. Notice the word "until".

With that being said. I like jt512's idea of clipping one rope through the anchor. That should eliminate the need for the exception if you are willing to allow the anchor to take the direct force.


aikibujin


Aug 31, 2005, 10:55 AM
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Re: Using singles as doubles? [In reply to]
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In reply to:
just dont clip 'em to the same piece...i think thats about all that would be worrisome.

Along the same line of thought: don't place two pieces even with each other and clip the ropes to them separately. If you must place two pieces even with each other, only clip one of the ropes to both pieces and sling appropriately.

When I'm climbing on doubles, if I'm about to go into a hard section, or if I'm looking at a long runout, I often like to place two pieces pretty close to each other and clip the doubles separately into each piece, so in effect I have a two-piece anchor to fall on. This does put a higher impact force on the climber, even though it lowers the impact force on the gear and the rope. It's not a concern when using doubles. But when using singles in this fashion, you might be subjecting your body to a harder fall than necessary. More worrisome in a high FF fall after a long runout.


blueeyedclimber


Sep 2, 2005, 1:29 PM
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In reply to:
To clarify VTG's point, you must avoid falling onto two singles clipped into the same piece, as the impact force will be dangerously high.

-Jay

The impact force will be higher on the piece, the climber, or both?


brutusofwyde


Sep 2, 2005, 1:47 PM
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yes.


blueeyedclimber


Sep 2, 2005, 1:59 PM
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Is the weight much of an issue when leading on two singles? I know the longer the pitch, the more of an issue it would be, but just how much are we talking?

Josh


vegastradguy


Sep 2, 2005, 2:56 PM
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not that much. i've led on a single and trailed a single...never really bothered me unless rope drag was serious on the lead line and/or the trail line was dragging as well due to a turn around a corner or something....

(that said, i prolly wouldnt want to do a Grade IV or V with two single lines, as i suspect the weight would start to take its toll at that point.)


jt512


Sep 2, 2005, 3:13 PM
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In reply to:
In reply to:
To clarify VTG's point, you must avoid falling onto two singles clipped into the same piece, as the impact force will be dangerously high.

-Jay

The impact force will be higher on the piece, the climber, or both?

It'll be higher on the piece (which may be the belay anchor!), the climber, and the belayer.

-Jay


blueeyedclimber


Sep 3, 2005, 11:07 AM
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To clarify VTG's point, you must avoid falling onto two singles clipped into the same piece, as the impact force will be dangerously high.

-Jay

The impact force will be higher on the piece, the climber, or both?

It'll be higher on the piece (which may be the belay anchor!), the climber, and the belayer.

-Jay

Gotcha! Would it make sense to only belay on one rope for a couple pieces, including the anchor?

Josh


jt512


Sep 3, 2005, 11:39 AM
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To clarify VTG's point, you must avoid falling onto two singles clipped into the same piece, as the impact force will be dangerously high.

-Jay

The impact force will be higher on the piece, the climber, or both?

It'll be higher on the piece (which may be the belay anchor!), the climber, and the belayer.

-Jay

Gotcha! Would it make sense to only belay on one rope for a couple pieces, including the anchor?

Josh

When you say to belay on one rope, are you referring to vegastradguy's suggestion that, in addition to the leader only using one rope for the first piece (or two), that the belayer only controls that one rope for the first piece or two? I don't like the idea. There seem to be too many opportunities for the team to make a mistake: the leader can clip the wrong rope; the belayer can brake with the wrong rope; the belayer can forget to go to standard double technique after the second piece, as planned; etc. If you are going to use single ropes as doubles, so far, I think my idea of clipping one rope thru the anchor is the safest solution. Your anchor should be unquestioningly bomber to do this because clipping the rope thru the anchor increases the impact force on it by about 65%. If the anchor isn't absolutely trustworthy then you should not use singles as doubles because it would put you in a lose-lose situation: you shouldn't clip one rope thru the anchor and you can't risk a double-rope fall onto it.

Frankly, I think the best solution is to go ahead and buy your doubles and practice with them on a couple of easy routes.

-Jay


vegastradguy


Sep 3, 2005, 8:22 PM
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Frankly, I think the best solution is to go ahead and buy your doubles and practice with them on a couple of easy routes.

or go find someone with doubles willing to show you the ropes. but yeah, i have to agree...actually practicing with singles poses some very real danger, and now that i think about it as an actual event happening, you're best off buying a set instead of practicing.

(my initial post was me thinking more on a theoretical line...like, could it be done- which it can, but, as jt pointed out, there may be too many variables for it to be practical).


Partner cracklover


Sep 6, 2005, 9:55 PM
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I think you're fine. I climb using doubles technique on one half and one thin single (9.2).

As has been said already, just make sure you're never looking at a fall where both ropes will catch you using the same upper piece. This is a very easy problem to avoid. By the way - you should avoid this with doubles too. Only twins are designed for it.

Have fun!

GO


jt512


Sep 7, 2005, 11:07 AM
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By the way - you should avoid this with doubles too. Only twins are designed for it.

Can you document that? It is a common practice to clip both double ropes into the same piece at the start of a pitch.

-Jay


Partner cracklover


Sep 7, 2005, 12:16 PM
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By the way - you should avoid this with doubles too. Only twins are designed for it.

Can you document that? It is a common practice to clip both double ropes into the same piece at the start of a pitch.

-Jay

I'll look into it when I have a few minutes to spare, but my understanding is that all UIAA certified ropes are certified as either single, half, or twin. Only twin ropes are designed and tested to be clipped together into one piece. Mind you, it's possible that some ropes may be certified as passing the requirements of a twin and of a half, or of a single and of a half.

GO


climbingaggie03


Sep 7, 2005, 12:43 PM
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I might be wrong on this, but I thought that there were only 2 classes for ropes from the UIAA, Single and double/twin and that using them as double or twin was personal preference.


Partner devkrev


Sep 7, 2005, 12:55 PM
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from the horses mouth


lewisiarediviva


Sep 7, 2005, 1:02 PM
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I was to the understanding, that you could use doubles as twins, but never use twins as doubles.

I just don't understand twins at all.


Partner cracklover


Sep 7, 2005, 2:36 PM
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I might be wrong on this, but I thought that there were only 2 classes for ropes from the UIAA, Single and double/twin and that using them as double or twin was personal preference.

You are mistaken. Okay, here's just one source:

From https://commerce5.the-information-age.com/Bluewater/Uploaded/Downloads/727200514235.pdf

In reply to:
SINGLE ROPE - for use in a single strand as a link in the safety chain.
HALF ROPE - for use together with another rope of the same type in a half rope system.
TWIN ROPE - use in pairs and parallel within a twin rope system.

Note - there are some ropes that are certified as both Half and Twin. (E.g. page 15 of http://www.singingrock.cz/Data/files/SINGING_katalog_EN_5.pdf )

And some that are certified as both Single and Half (e.g. http://www.bluewaterropes.com/home/usechart.asp )

But most are certified as only Twin or Half (e.g. http://www.bluewaterropes.com/home/usechart.asp
http://www.mammut.ch/mammut/images/ropes/overview_e.jpg (all of mammut's twins and halfs)
http://www.bdel.com/gear/detail/ice_twin_detail.php#compare (all of Beal's twins and halfs)

JT512 - all certification tests for EN 892 (upon which the UIAA requirements are set) are done with a single strand of SINGLE, a single strand of HALF, and two strands of TWIN. There are lots of references to this online, but to get the actual EN 892 text costs around $150. I'm sorry, I don't have that kind of chump change lying around. If you can find a pirate copy on the web - more power to you - I've got to get back to work!

GO


jt512


Sep 7, 2005, 3:23 PM
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In reply to:
In reply to:
I might be wrong on this, but I thought that there were only 2 classes for ropes from the UIAA, Single and double/twin and that using them as double or twin was personal preference.

You are mistaken. Okay, here's just one source:

From https://commerce5.the-information-age.com/Bluewater/Uploaded/Downloads/727200514235.pdf

In reply to:
SINGLE ROPE - for use in a single strand as a link in the safety chain.
HALF ROPE - for use together with another rope of the same type in a half rope system.
TWIN ROPE - use in pairs and parallel within a twin rope system.

Note - there are some ropes that are certified as both Half and Twin. (E.g. page 15 of http://www.singingrock.cz/Data/files/SINGING_katalog_EN_5.pdf )

And some that are certified as both Single and Half (e.g. http://www.bluewaterropes.com/home/usechart.asp )

But most are certified as only Twin or Half (e.g. http://www.bluewaterropes.com/home/usechart.asp
http://www.mammut.ch/mammut/images/ropes/overview_e.jpg (all of mammut's twins and halfs)
http://www.bdel.com/gear/detail/ice_twin_detail.php#compare (all of Beal's twins and halfs)

JT512 - all certification tests for EN 892 (upon which the UIAA requirements are set) are done with a single strand of SINGLE, a single strand of HALF, and two strands of TWIN. There are lots of references to this online, but to get the actual EN 892 text costs around $150. I'm sorry, I don't have that kind of chump change lying around. If you can find a pirate copy on the web - more power to you - I've got to get back to work!

GO

None of this really implies that doubles (halves) can't be clipped together. Clearly, twins aren't intended to be strong enough to be clipped separately.

-Jay


brutusofwyde


Sep 7, 2005, 5:20 PM
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In reply to:
none of this really implies that doubles (halves) can't be clipped together. Clearly, twins aren't intended to be strong enough to be clipped separately.

-Jay

And, generally, when those half ropes which are not certified as twins are clipped together, they exceed the maximum impact force of the UIAA test, and thus fail the test for certification as twin ropes (peak force less than or equal to 12 Kn.)

Clearly, there are advantages and disadvantages to clipping half ropes to the same piece. Folks who do not know what those tradeoffs are, should not be climbing on half ropes.

There is currently one rope on the market that I know of that meets the certification requirements for all 3 classes of rope: Single, Half, and Twin. This is the Beal Joker.

Brutus of Wyde
Old Climbers' Home
Oakland, California


aikibujin


Sep 7, 2005, 7:55 PM
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And, generally, when those half ropes which are not certified as twins are clipped together, they exceed the maximum impact force of the UIAA test, and thus fail the test for certification as twin ropes (peak force less than or equal to 12 Kn.)

This is interesting. How did you arrive at this conclusion? The reason I ask is because this is important for me to know. When I'm going into a hard section of looking at a long runout, I often like to place two pieces evenly or very close to each other, and clip my doubles separately to each piece. If the pieces are even, in a fall the pieces share the force, but both strand of doubles catches the climber, so the impact force on the climber is basically the same as if I had clipped both ropes to the same piece. I will have to re-think this practice if it results in greater than 12kN impact force in a high FF fall.

The only other time I've seen someone quantifying the impact force when clipping two ropes together is rgold in this thread:
In reply to:
The "hard catch" resulting from clipping both strands can be quantified; the sum of the tensions in both ropes will be the square root of 2 times the tension that would have resulted had only a single strand caught the fall. Since the square root of 2 is approximately 1.4, clipping both strands will result in loads to the system that are 40% higher than the loads imposed by a single strand.

Of course, I'm not a math professor, and I cannot found any actual tests done to measure the impact force of doubles used as twins. So I'll assume rgold is right.

To see if I'm in danger of high impact forces in a fall when I'm clipping my doubles to the same piece, I ran some quick calculation for the ropes I use - a set of Beal Verdons, with a impact force of 5.3kN. But doubles are tested with 55kg of weight (which is a fact that annoys me to no end). So I had to find out its impact force with a 80kg weight. Using the equation given on Beal's Impact Force site, I solved for Young’s Modulus of my rope, which is 11712. Plugging this number back in the equation with 80kg of weight in a FF2 fall, I get 6.9kN as the impact force. 40% higher of 6.9kN is 9.66kN, so if rgold is right, this is still within the 12kN limit.

Of course, ropes don't always behave according to equations, their construction also plays a big part in the picture. That's why only Beal is able to make a rope that's single, double, and twin certified. The Beal Joker's impact force when used as twins (9.5kN) is only 16% higher than its impact force when used as a single (8.2kN). So I think rgold's caculation of 40% is probably pretty close to the real world.

In reply to:
Clearly, there are advantages and disadvantages to clipping half ropes to the same piece. Folks who do not know what those tradeoffs are, should not be climbing on half ropes.

I agree. Just because doubles are only tested on a single strand doesn't mean there is never a situation where you should clip them both to the same piece. To say you must clip them separately because the UIAA only tested them in a single strand, is like saying that we all must go on a diet, because UIAA only tested doubles with 55kg of weight (121 lbs).


Partner cracklover


Sep 7, 2005, 9:23 PM
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To say you must clip them separately because the UIAA only tested them in a single strand, is like saying that we all must go on a diet, because UIAA only tested doubles with 55kg of weight (121 lbs).

I didn't say you *must* do this or *mustn't* do that. I said they weren't designed to do so. And to put that back in context, the point I was making here:

In reply to:
make sure you're never looking at a fall where both {single} ropes will catch you using the same upper piece. This is a very easy problem to avoid. By the way - you should avoid this with doubles too. Only twins are designed for it.

is that the force that your upper piece will feel from two single or two double ropes putting a peak force on it at the same time, may be higher than you think - just beware!

Not to take things too far off topic, but one of the things I ran into in my search for the EU standards was the accident report for Goran Kropp's death. Quite clearly, one of the contributing factors was that the rope that was used was old and not very stretchy. After the first piece pulled because it was badly placed, the biner on the second piece broke because the impact force was very high - higher than it could have been if it had been a new rope. Somehow the rope didn't have the stretch that was expected of it - perhaps from many falls on climbs they'd done that day, or perhaps from extensive toproping and/or rappeling in the life of the rope.

My point is that when you put two ropes on the same piece, you're effectively doubling the diameter of the rope catching you - raising the peak impact force on that piece. And Goran Kropp's accident shows us (as if we didn't already know this) that ripping pieces can be very, very bad.

GO

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