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Chockstone Forum - Trip Reports

Tells Us About Your Latest Trip!

 Page 2 of 3. Messages 1 to 20 | 21 to 40 | 41 to 55
Author
Mild Peril - Rated PG
egosan
11/05/2010
12:21:18 PM
On 11/05/2010 mikllaw wrote:
>One isssue with using them as twins then double (i.e. having them both
>clipped into the same biner, then having only one clipped into a higher
>draw) is that you could get one rope rubbing/melting over another where
>they are both clipped together.
>
>

Aye, some double ropes are rated as twins as well. If they are not rated as twin you should not clip both in the same biner. The two issues being friction and impact force.
f_ladou
11/05/2010
2:54:38 PM
On 11/05/2010 pmonks wrote:
>I think this has been discussed in other threads, but I never clip both
>ropes into the same runner, regardless of which direction I'm headed.
>In those rare situations where I do want to clip both ropes into the same
>piece of protection I'll put two runners on the bolt / gear and then clip
>each rope into its own runner. [...]

First many thanks Peter for taking the time to explain: this is much appreciated. On the next climb, I'll sure think differently.

For a couple of years now I brushed aside conflicting definitions/viewpoints on twin ropes versus double ropes. In fact, I do not even know if my current double ropes are indeed double or twin! Also, I never thought about Michael's point re rubbing/melting but that's certainly valid if stretch is uneven (any reported case?).

Can anyone point me to a decent link or resources re clipping techniques? Perhaps, as Peter mentioned, even in this forum?


ajfclark
11/05/2010
2:56:08 PM
http://www.chockstone.org/techtips/tworopes.htm

One thing not mentioned in there is tying in. If I had a green and a blue rope, I'd flake them side by side and note which was on which side (say green on the left, blue on the right). When I tied in, I'd face the cliff and tie the green through my harness to the left of my belay loop and the blue to the right.

Likewise, as a belayer, facing the cliff, the right rope will go through the right side of my belay device, the left rope through the left.

For whatever reason this process seems to help me keep everything untwisted. Maybe I'm just a little special and need the extra help (or a little OCD)?
mikllaw
11/05/2010
5:10:55 PM
we were so wedded to doubles int he dark ages that I once saw (and heard!) animal fall off the roof at Ball's head in Sydney Harbour and get the rope burbn from hell as he fell into the V of the 2 ropes. Long healing cracking puss filled burn and lots of rum

ajfclark
11/05/2010
5:28:04 PM
On 11/05/2010 mikllaw wrote:
>we were so wedded to doubles int he dark ages that I once saw (and heard!) animal fall off the roof at Ball's head in Sydney Harbour and get the rope burbn from hell as he fell into the V of the 2 ropes. Long healing cracking puss filled burn and lots of rum

Where you typed burbn rather than burn... Is it a coincidence that it's bourbon sans the letter o?
olbert
11/05/2010
6:01:27 PM
On 11/05/2010 egosan wrote:
>Aye, some double ropes are rated as twins as well. If they are not rated
>as twin you should not clip both in the same biner. The two issues being
>friction and impact force.

As I understand it you should never ever chop and change between twin/double clipping styles on the same pitch as during a fall the ropes will take different loads, stretch a different amounts and rub against each other under load - bad!!

As I understand it the reason that using doubles as twins is bad is because the impact forces generated during the fall are greatly increased. Im wondering if this would be a major problem if the following conditions are met -
1) It is a sport route - practically no chance of top piece of protection ripping
2) There is zero chance of a factor 2 fall - ie single pitch or if belayer is significantly below anchor point and the lead rope runs through the anchor point
3)Belayer performs a dynamic belay (optional)

I believe that the impact on the individual half ropes would be no more using them as twins then doubles as although the total impact force may be higher it should be evenly distributed over both ropes. Each rope would therefore only take a reasonable amount of impact force.

I am really truly interested to find out if I am completely wrong here though I would like to understand why! (ie I dont want answers of "my doubles came with explicit instructions not to use them as twins therefore you are wrong").
olbert
11/05/2010
6:04:30 PM
So basically, if I went to Nowra and only had a set of doubles would it be reasonably 'safe' to treat them as twins?
egosan
11/05/2010
6:11:18 PM
Why would you subject your kidneys other bits to the higher forces? Nothing wrong with using the doubles as doubles on sport anchors.
olbert
11/05/2010
6:16:36 PM
On 11/05/2010 egosan wrote:
>Why would you subject your kidneys other bits to the higher forces? Nothing
>wrong with using the doubles as doubles on sport anchors.
True, but this is a hypothetical, that's not the point.
mikllaw
12/05/2010
8:19:50 AM
I think the impact question is relevant to a factor 2 type situation, where the belay is basically locked up (grigria nd fat rope?). In most real cases there's a lot of slip in the belay and lift of the belayer. One subtle difference between singles and twins is that twins supply a lot more surface area and braking force. using as doubles where one rope might be doing all the catching is a much more slippery option.

So I'm happy to use my free facebook 9mm ropes as doubles or twins (and sometimes even as singles), and let twins slip a bit if you're holding a factor 2

IdratherbeclimbingM9
13/05/2010
12:26:06 PM


Classic snarfu! and probably why belayer took the pic, as f_ladou would never have known (aside from experiencing bad rope drag at the time), without it.
... ~> Leader is saying (?) "Oy mate, don't come up here, as the rope won't let you go any further!"
Heh, heh, heh. ☺


On 11/05/2010 mikl wrote:
>One isssue with using them as twins then double (i.e. having them both clipped into the same biner, then having only one clipped into a higher draw) is that you could get one rope rubbing/melting over another where they are both clipped together.

On 11/05/2010 ajfclark wrote:
>Could that also be a concern if you got them twisted as in the above photo?

Definitely!
The minimum result would be a glazed sheath in the event of a good fall.
The worst could be like the rope-jump fellow who died as a result of one crossing another(?) during his last jump.

If the DNA twisting was chronic and the fall small and soon after the twisting, then it would probably just lock off the rope as a twist on the nearest krab; ... but then you run the risk of that krab partially opening due the twist against the gate, and the open gate causing tear/ripping of the sheath.

ajfclark
13/05/2010
12:36:36 PM
So in short it's A Very Bad Thingtm.
One Day Hero
13/05/2010
4:13:56 PM
On 13/05/2010 ajfclark wrote:
>So in short it's A Very Bad Thing

It's not a very bad thing in terms of getting injured, it is a very bad thing in terms of trying to enjoy a climb whilst towing an elephant!

There is no problem with twin clipping doubles since, by definition, once you clip them into something you can't factor 2. Also, if you do factor 2, both ropes will be catching it anyway (nothing clipped, climber falls past belayer....think about it)

On straight up bolted pitches, twin clipping is the easiest way to avoid DNA. On wandery or dogleg pitches maintaining a left rope and right rope is the go (try and look to the next bit of gear before deciding which rope to clip to this bit of gear)

By the way, that photo is the coolest example of badly managed doubles I've ever seen!
Welcome to planet drag, sucker!
technogeekery
14/05/2010
12:53:07 PM
"There is no problem with twin clipping doubles..."

Unless they are rated as both twin/double, I don't think its a good idea to twin clip doubles. Apart from rope on rope wear potential mentioned already, doubles are designed to be used individually - falling on both of them together in one piece is going to have a much greater loading on you and the pro than if they were being used properly. If you've got a straight-up route and you must use doubles rather than a single or twins, just clip alternate pro with each rope - has the added benefit of having less slack out on one rope during the clip. If you are worried about a big fall onto the first piece, maybe consider finding another piece of pro (or using another draw on the same bolt) and clipping both ropes seperately.

My $0.02.

I agree that the pic could be a textbook example of how not to use doubles lol. I've had some pretty clusterf&%$ in my time with doubles too...
Olbert
14/05/2010
1:09:42 PM
On 14/05/2010 technogeekery wrote:
>"There is no problem with twin clipping doubles..."
>
>Unless they are rated as both twin/double, I don't think its a good idea
>to twin clip doubles. Apart from rope on rope wear potential mentioned
>already,
Not if they are clipped solely as twins for a particular pitch. How would one move more then the other? The length of rope out is the same for both ropes.

>doubles are designed to be used individually - falling on both
>of them together in one piece is going to have a much greater loading on
>you and the pro than if they were being used properly.
Well..if you are doing a trad route this is a valid point. If you are doing a sport route as this thread is about then if a bolt might fail from that then I aint trusting that bolt!!
I have fallen on doubles as twins and I did not notice the difference between that and a normal fall on a single. Of course a fall on a normal double would be much longer and the difference noticable.

> If you've got a
>straight-up route and you must use doubles rather than a single or twins,
>just clip alternate pro with each rope - has the added benefit of having
>less slack out on one rope during the clip. If you are worried about a
>big fall onto the first piece, maybe consider finding another piece of
>pro (or using another draw on the same bolt) and clipping both ropes seperately.
Hang on, so if you are worried about a fall onto the first bolt, then clip another draw and clip the second rope in. That would mean that a fall would be caught by both ropes and so you would get a "greater loading on you and your pro". Whats the difference between that and clipping both ropes into the same piece of pro?
There is presumably the same length of rope out and so there will be no slippage between them. (Of course if you use the doubles for separate pieces of pro subsequently then there will be slippage.)

It is impossible to create a worse factor 2 fall scenario if you clip this way as for a factor 2 fall to occur, by definition, you cannot have clipped any pro. So if you factor 2 fall it is irrelavent if you planned to use the ropes as twins or doubles as you havent clipped anything yet.

In some situations its a lot easier/quicker/simpler to do verticle pitches with double ropes as twins. I still dont see the harm in using doubles as twins as long as you do so for the entirity of a pitch.

Olbert
14/05/2010
1:20:41 PM
On 14/05/2010 technogeekery wrote:
>"There is no problem with twin clipping doubles..."

Of course Im not attempting to change your attitude. Im sure you will continue to use doubles as doubles and never as twins, and that is fine. I have no problem with that.

I am just trying to find out whether there is a reasonable reason not to use doubles as twins as this is a practice I have done and probably will do again. I truly want to know if there are examples of accidents because of this or good theoretical reasons not to do it.
mikllaw
14/05/2010
1:42:08 PM
there is a small potential problem if you have a big fall onto bad gear and a totally locked off belay, with the belayer lashed to the spot also:- the impact force will be higher on the doubles (used as twins) than the twins.
But if the gear is bad, you should be slipping the ropes, if it's not bad it doesn't matter.
If the fall is onto a belay they act as twins either way, and you better hope the belay slips and the anchors hold.
technogeekery
17/05/2010
5:49:24 PM
Hi Olbert

I'm not going to be too dogmatic about this or put myself up as an expert by any means. Obviously do your own research and draw your own conclusions, and then go for whatever satisfies you. I only really chipped in here because a) the picture in the thread made me laugh and remember my own misadventures with half-rope techniques, and b) my own understanding is that clipping pro with both half-ropes is sub-optimal for the 2 reasons I mentioned. Don't get me wrong, I don't think you are going to die if you clip both half ropes onto a piece of pro with the same draw, and then take a good fall on it - but I do think you increase the risk unecessarily.

1) Ropes running over each other are potentially hazardous. Your point is probably valid, if it is pretty much straight up climbing, and you clip everything together, and its bolted climbing, you are probably sweet from the aspect of melting ropes. I come from a trad background where those circumstances very seldom come together, and just hate having rope on rope anywhere in the system.

2) Increased maximum force. I guess there are 2 aspects to this - force on the pro, and force on the climber. I'm no expert, and I haven't been able to find anything definitive on this online / from the manufacturers, so I stand to be corrected. But if I remember right, the UIAA deems 12kN to be the max force a climbing rope may exert on a climber. Half ropes are stretchier than singles of course - here are some typical figures from the manufacturer:

Sterling Kosmos Evolution 10.2 single - Max force 8.8Kn
Sterling Kosmos Duetto 8.8 double/half - Max force 6.1Kn

But if you use two Duettos clipped to the same piece of pro, what is the force exerted on the climber? Could it be double the rating - ie 12kN? I don't know the answer, and I can't find reliable test results online. I doubt its double, but its certainly higher, perhaps considerably higher. Will that increase the possibility of you getting hurt by the fall?

And on the pro, where the forces are what, double the force on the climber side? For trad, limiting this force is critical, and I feel much the same way about bolts (I'm chicken). Michael makes good points about belaying skills which considerably reduce real-world loadings. You make points about bolts that should be strong enough to trust, but maybe its my trad background, I just don't trust bolts all that much.

Sure you are unlikely to pull the piece or break your back - but why increase the risks?

Anyway, here in Japan I'm mostly doing bolted sport routes (thats what is out there, mostly) and enjoying the simplicity of single rope technique on a beefy 10.2, and clipping bolts. And when I'm back in the groove and doing my favourite trad/mixed multipitch again, I'll be doing it on something like the Beal Joker, which is certified for single, double/half AND twin use. Impact forces are about 8kN (single), 5.7kN (double/half) and 9.2kN (twin), mostly using it in double mode and happy to use it in single or twin mode if I ever need to.
alex_f
18/05/2010
11:28:22 AM
>Impact forces are about 8kN (single), 5.7kN (double/half) and 9.2kN
>(twin), mostly using it in double mode and happy to use it in single or
>twin mode if I ever need to.

That answers your question. The double-rope rating is for a 55kg load on one strand, the single-rope rating for an 80kg load on one strand and the twin-rope rating for an 80kg load on two strands. I.e. the impact force will increase from 8kN to 9.2kN if two ropes are clipped into the same piece of pro instead of only one rope.
mikllaw
18/05/2010
12:05:00 PM
On 18/05/2010 alex_f wrote:
I.e. the impact force
>will increase from 8kN to 9.2kN if two ropes are clipped into the same
>piece of pro instead of only one rope.

This is a bit "academic", these forces only occur if you are tied off to the belay and not simply belayed. Most belay devices slip at about 3kN

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There are 55 messages in this topic.

 

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