Daisy chaining your climbing rope

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)?

The hypothetical started when talking about towing stuck trucks bled into the vein of more climbing-specific materials.

If by 'daisy-chaining' you mean making it loop back on itself in short loops for the entire length of the rope then I do it all the time just before I throw them in the washing machine.

Oh I mean specifically under load.  As in Knot "X" weakens the rope by "X"% when under load.

I would think that if you were to load a daisy chained rope would be weakened the same amount as most any girth or hitch weakens a rope. However, I also can't think of a single situation where you would load a daisy chained rope.

Yah, neither can I.  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.  

g7634ppom wrote:

Yah, neither can I.  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.  

Tow straps for stuck vehicles should be rated to 20K lbs minimum. Even a self extraction winch should be rated to at least 2x vehicle weight.

Why was the rope Daisy chained?  Every "chain" weakens the rope about 30% at the bends.  

i think with static ropes in boating it has been used to add a dynamic absorption element. not 100% sure if that’s a typical use case or not.

Of course any knot weakens the rope to some degree. But there is no theoretical difference in strength between a rope with one knot and a rope with 30. More daisy chain loops does not equal a weaker rope.

rockklimber wrote:

Why was the rope Daisy chained?  Every "chain" weakens the rope about 30% at the bends.  

It's not additive.

Marc801 C wrote:

It's not additive.

exactly,  each knot or bend in the rope will weaken the rope at the point where the rope makes the bend, so there will be more weak points in the rope, but each weak point will be roughly the same strength as every other weak spot, so adding daisy chain loops won't make the overall strength of the rope any less than a single daisy chain loop would make it.

Marc801 C wrote:

It's not additive.

I never said it was additive.  It is weaker at each and every bend.  Meaning there are multiple weak points.  

Ken Noyce wrote:

exactly,  each knot or bend in the rope will weaken the rope at the point where the rope makes the bend, so there will be more weak points in the rope, but each weak point will be roughly the same strength as every other weak spot, so adding daisy chain loops won't make the overall strength of the rope any less than a single daisy chain loop would make it.

But it creates many more potential points of failure.  

rockklimber wrote:

But it creates many more potential points of failure.  

Sure, but that is no worse than a single potential point of failure due to a single knot.  The rope will break at the weakest point once the load exceeds the strength at that point.  Having multiple equivalently weak points doesn't decrease the safety of the rope or increase the probability of failure at a given load.

Ken Noyce wrote:

Having multiple equivalently weak points doesn't decrease the safety of the rope or increase the probability of failure at a given load.

However, you could argue that any given type of knot will decrease the strength of a rope by 20-30%; the exact amount depending on the intricacies of how it is tied/dressed. The more knots you tie, the more likely it is that one of them is going to be the worst case scenario knot and you'll end up on the higher end of the range (in this case 30%).

Ken Noyce wrote:

Sure, but that is no worse than a single potential point of failure due to a single knot.  The rope will break at the weakest point once the load exceeds the strength at that point.  Having multiple equivalently weak points doesn't decrease the safety of the rope or increase the probability of failure at a given load.

Unfortunatelty we dont live in an ideal world.  Theoretically, If the rope was brand new then each chain would be roughly the same strength.  But used ropes  have frayed fibers, sharp dirt crystals embedded, ppl stepping on them, UV exposure, etc which creates weak spots.  

My previous comment still stands.  

rockklimber wrote:

Unfortunatelty we dont live in an ideal world.  Theoretically, If the rope was brand new then each chain would be roughly the same strength.  But used ropes  have frayed fibers, sharp dirt crystals embedded, ppl stepping on them, UV exposure, etc which creates weak spots.  

My previous comment still stands.  

Sure it still stands, but it still doesn't matter.

Ken Noyce wrote:

Sure it still stands, but it still doesn't matter.

It does to those who have a little knowledge and common sense.  

rockklimber wrote:

It does to those who have a little knowledge and common sense.  

Nope, it doesn't.

Ken Noyce wrote:

Nope, it doesn't.

Yes.  It does.  

rockklimber wrote:

Yes.  It does.  

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