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tradguy
Nov 26, 2002, 9:31 PM
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It was suggested in another thread that using double ropes (~9 mm) in twin fashion (ie clipping both ropes to all the pieces of pro) could be bad, due to higher impact force exerted to gear and/or climber from a lead fall. Is this a legitimate concern? Does anyone have any experience with this, or know of manufacturer's literature saying whether this is an ok practice or not?
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mountainmonkey
Nov 26, 2002, 10:08 PM
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http://www.usmga.net/guidelines/guidelinesropes.htm
"Typically half ropes should not both be clipped to the same piece of protection, as this has the potential to generate dangerously high impact forces in the event of a leader fall."
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tradguy
Nov 26, 2002, 10:43 PM
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My question about that statement is whether it's "dangerously high" due to the effects on the climber's body, or the possibility of pulling out gear. I guess I'm curious if it would be equally bad to twin lead with double ropes on a sport route, or if it's just a concern of pulling your pro.
[ This Message was edited by: tradguy on 2002-11-26 14:47 ]
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mountainmonkey
Nov 26, 2002, 10:55 PM
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Are you willing to risk your life by disregarding what manufacturers specify?
Why would you want to "twin lead with double ropes" in the first place?
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newland
Nov 26, 2002, 11:10 PM
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The distances you fall in sport climbs are small. don't worry about the impact force.
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jt512
Nov 27, 2002, 4:08 AM
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Quote:The distances you fall in sport climbs are small. don't worry about the impact force.
Uh, last time I checked, impact force was proportional to fall factor -- the ratio of the distance falling to the amount of rope out -- not to the distance fallen itself.
-Jay
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tradklime
Nov 27, 2002, 5:02 AM
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I will clip both half ropes when I have a bomber piece and the rope travel is fairly even. The concern is with the impact force on the piece.
Another concern with half ropes is that they are skinny and less resiliant against being cut, if one gets cut, you are falling to your next clipped piece. Also, they are tested and rated based on 55kg rather than 80 kg. They are not realy designed for a high fall factor fall on a single line.
It kind of comes down to the circumstance and a balance of the various considerations. One of the reasons half ropes aren't for the inexperienced.
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awsclimber
Nov 27, 2002, 5:09 AM
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I always understood that the main problem w/ twins is that they must be equally dynamic because even the slightest diffence in stretch will create friction between the two ropes, and friction between two pieces of nylon very quickly can melt them apart.
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pbjosh
Nov 27, 2002, 8:32 AM
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Given the price of half ropes vs. singles, I wouldn't use them where I could use a single. I also wouldn't use them like twins. Even twins exert a reasonably high force on gear so I won't use them in a lot situations... Twins really excel at Red Rocks 'cause they're lighter than doubles and you can make your long rappels very easily. I am personally not a big fan of the "single + 7mm rap line" method... Halves really excel for ice climbing or wandering trad routes. Singles excel whenever you can get away with just using a single
josh
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tradguy
Nov 27, 2002, 7:00 PM
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Quote:Are you willing to risk your life by disregarding what manufacturers specify?
Of course not. However, the passage you quoted earlier said " Typically half ropes should not both be clipped to the same piece of protection." typically. To me this implies that there are instances when it would be ok or acceptable to do so. All I'm saying is that the article was a bit vague.
Quote:Why would you want to "twin lead with double ropes" in the first place?
The thought occured to me from a different thread discussing methods to avoid a messy hanging belay at the top of a long (ie 150 ft) single pitch sport route. My thought was that a person could lead it with doubles, clipping both ropes to every piece, and then pull one up out of the draws and through the anchor after he got to the top and then rap down, cleaning draws along the way. They would then have a top-rope set up for the second to climb. The reason for considering doubles rather than using single and trailing a second rope is that I have a 100m x 9mm bi-color rope that I tie into the middle at the color change and use for double-rope leading. The resulting top-rope then has no knots to pass through the belay.
Clear as mud, huh? Well, it sounded good in theory, but with the idea of higher impact forces doesn't really sound the greatest.
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mountainmonkey
Nov 27, 2002, 8:29 PM
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The 'typically' thing was posted directly from the website and they say when it might be ok to do that. I don't think they want to say it is ok all the time because every situation where you would use it would produce different results. Sometimes it is ok, other times it could be disasterous. A good knowledge of the system involved is needed to evaluate an determine if it is ok for a given situation.
From the system you propose, you will still be ok clipping every other piece as you would with normal double rope system - then just pull one through the draws. It won't be very practical to do it if it is overhanging most of the way - but in that case you are better off leading anyway. If you are not going to be falling frequently while leading the route (and there is NO rope cut potential or high fall factors), you can just use one double rope, but you won't see that reccomended by the manufacturer either.
The only question I have is: How are you going to rap on one line and still have it set up for a toprope at the same time? I have some ideas but I would like to hear yours.
Another note: If you pull one rope through the draws and the other is stationary, there is a potential to melt the sill rope with the moving one.
[ This Message was edited by: mountainmonkey on 2002-11-27 12:31 ]
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tradguy
Nov 27, 2002, 8:49 PM
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I was thinking of this in a mostly vertical, perhaps very slightly overhanging situation. To be honest, I didn't have any particular route or area in mind, it was just a theoretical pondering (see - strange things happen when work gets boring).
I understand what you are saying about the rope friction issue. I thought about that, but again, with a basically vertical route, I think the motion of the rope in a horizontal plane that would be induced by pulling the rope UP would be sufficient to ensure separation from the other strange, and thus not damage the sheath. Besides, it would be tough to pull it up fast enough for long enough time to do any damage.
My intent on rapping would be to double rope rap, but since you asked, here's the 3 most feasible methods I can think of:
1.) have belayer tie off the strand running through the draws (ie anchor to tree or boulder with sling clipped to figure 8 on a bite), and single line rap. not really preferred, but would work ok.
2.) have belayer lower me after threading the anchors (if I were doing this, I would leave slings and biners of my own at the top so as not to put undue wear on the rap anchors, and have the last climber retrieve them.)
3.) Rap like normal, and pause momentarily to remove the draws on the way down with my other hand.
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mountainmonkey
Nov 27, 2002, 9:16 PM
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that makes sense
Another thing I would like to mention about using double ropes on sport climbs is that a very good belayer can feed one rope while keeping you tight to your previous bolt - then you don't have a loop of slack out while clipping. If it is very hard, you can even have two belayers - very low rope drag, no short roping, low rope weight when clipping, no loop of slack when clipping, and the belayer is even redundant - HA!
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tradklime
Nov 27, 2002, 10:36 PM
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I have used a similar technique on difficult cracks where placing gear is strenuous and I wanted to work the moves.
While hanging on one piece and one rope you can place gear above your head and clip the other rope into it. Helps with the head games of working a crux, if your next piece is within reach. This technique will obviously eat up gear, and holds (jams/ finger locks) for that matter, but has come in handy in the right circumstance.
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brutusofwyde
Dec 1, 2002, 6:25 AM
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Some of the newer, thinner half ropes are designed such that they can be used with either twin or half rope technique.
Often when using half ropes, especially when the protection is sparse, I will clip both ropes into a single bomber piece, using different carabiners for each rope to prevent the rope-on-rope friction.
Any piece less than bomber gets a screamer, regardless of the shock-absorbtion characteristics of the rope I'm using.
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coclimber26
Dec 1, 2002, 3:11 PM
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The manufacturer says this is dangerous and twins should be treated as a single rope being clipped into the same pro and not alternated...I don't know any better so I will trust the manufacturers
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brutusofwyde
Dec 1, 2002, 8:30 PM
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> The manufacturer says this is dangerous
to what does "this" refer? Using screamers on marginal pieces? clipping in both half ropes to a bomber piece before long runouts? Using halfropes in twin configuration, with screamers on anthing that isn't bomber pro? or using twins in half rope configuration (which I never suggested)?
Beal iceline is 8.1 mm and can be used in half-rope configuration. If you don't believe me check their website.
> and twins should be treated as a single
> rope being clipped into the same pro and
> not alternated...
Never said otherwise.
> I don't know any better so I will trust
> the manufacturers
I'll make my own choices based on all available information at hand.
Brutus
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raybo
Dec 3, 2002, 11:22 PM
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If you are leading with double ropes, clipping each strand into alternate protection, and you fall, isn't all of your weight caught by the last single strand that you clipped? How is this different from just leading with the single strand?
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tradklime
Dec 4, 2002, 4:18 AM
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Depending on how spaced your placements are, your other rope may take some of the fall. If it does not and the first rope breaks, your second one is there to catch you.
That is really part of the argument for clipping both ropes into one bomber piece, especially if your last piece is far below or none existant.
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brutusofwyde
Dec 11, 2002, 2:06 AM
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Just double checked and the Beal Ice Line (8.1mm) is indeed rated for use as EITHER a twin rope or as a double rope. HTH.
Brutus
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