Daisy chaining your climbing rope

Ken Noyce wrote:

Since you are so sure, please explain to me why.

Probability of failure increases and it can fail at lower forces.  

rockklimber wrote:

Probability of failure increases and it can fail at lower forces.  

Yes it can fail at lower forces, no probability of failure does not increase because the forces required for it to fail are still way beyond the forces that are possible in climbing.

Ken Noyce wrote:

Yes it can fail at lower forces, no probability of failure does not increase because the forces required for it to fail are still way beyond the forces that are possible in climbing.

While you two are having a pissing contest, maybe keep the context of the OP in mind: 

"It came about as we were hi-lift jacking out a 8,000 lb truck with about 25 daisy chain loops added to the towline.  I felt fairly uncomfortable with having so many loops with that much strain, and as we were getting the truck unstuck the towline (rated to 7k lbs) nearly snapped."

Marc801 C wrote:

While you two are having a pissing contest, maybe keep the context of the OP in mind: 

Marc,  Yes, this is what got the OP thinking about the question, but the question was specifically a hypothetical question about your climbing rope, and not about the incident that got the OP thinking about it.

Ken Noyce wrote:

Yes it can fail at lower forces, no probability of failure does not increase because the forces required for it to fail are still way beyond the forces that are possible in climbing.

Probability is dependent on the number of possible failures.  And if you read the OP again the forces they are generating are much higher than the forces that are possible in climbing.   

Marc801 C wrote:

While you two are having a pissing contest, maybe keep the context of the OP in mind: 

I was.  That's why I kept responding.  He was thinking about climbing forces.  I was responding to the actual situation described in the OP.  

Saw this and wondered aloud why the "old timers" did this and left this:

https://www.mountainproject.com/photo/111260423

g7634ppom wrote:

A question came up at work today, and I won't give away all the hypothetical, but it boiled down to this question: If you were to daisy chain your climbing rope (I've never had to and don't intend to - again, it's a hypothetical), would that weaken the rope in any way, especially in any progressive sense (more daisy chain "loops" = an increasingly weaker rope)?

I'll just leave this here as the OP's actual question, along with the fact that having multiple zero probability scenarios for failure still results in a probability of zero.

Ken Noyce wrote:

I'll just leave this here as the OP's actual question, along with the fact that having multiple zero probability scenarios for failure still results in a probability of zero.

They later added why the question came up.  You were answering the hypothetical.  I was responding to the actual scenario which brought up the OP.   I still say the probability is not zero, but it is so small to most people who dont understand or work with statistics that it is essentially zero.  .  

To be clear, I think everyone is talking about this structure:
https://en.wikipedia.org/wiki/Chain_sinnet

Where we ~triple the cross-sectional area, though do indeed add a lot of bends.

Suppose our chaining did weaken the rope by 30% as someone above suggested, we have 3x more strands to share the load. In our thought experiment we might thus reasonably guess that the resultant strength is ~2x stronger than the single strand.

That makes intuitive sense to me, a daisy chained rope is a whole lot of nylon per square meter, looking at the thing it has more meat than a single stranded rope.

Of course, this is ignoring the termination points of a daisy chain, where it resumes being a single strand again.

Whilst sitting in my armchair, I daisy chained a bit of polyester thread, with a strength of around 10-11N, the resultant broke at 27N (connected it to the scales via wrapping 5 times around a rod and finishing with half hitches, it broke mid chain). It's a terribly weak and flawed bit of empiricism, but it supports my intuition.

Obviously the correct answer to this question is for someone to have connected a bunch of daisy chained climbing ropes to a load cell and came back with the results, any other means of deriving an answer risks disagreeing with reality. In less words, this thread has a bit of uninformed shit in it, my post included.

Roy Suggett wrote:

Saw this and wondered aloud why the "old timers" did this and left this:

https://www.mountainproject.com/photo/111260423

I'd guess some of these things were running through their mind:
- How can I hang a rope such that its a useful aid to people ascending/descending
- Knots make it easier to hold, and with different length strands in between will create space to get your foot/hand in (eg: https://cdn-files.apstatic.com/climb/106929557_medium_1494151802.jpg)
- Two strands will last longer

^^^  yeah, but why leave it hanging there with the old army surplus angles sticking so far out?  I presumed they planned on coming back soon and never did.  The puzzler for me was the time and skill to set up the rope like this juxtaposed against the "apparent" lack of planning.  Who knows...a storm, an injury, no judgement here, shit happens when putting up a line.  I know how I feel when someone complains about the direction, distance between bolts, etc., and knows nothing about the circumstances/situation when the line was going up not to mention the hard work.  So kudos to them and their daisy chaining skills.  I wish I knew who they were to give them credit on that route.