Friday, December 17, 2010

Ropes & Redundancy

In tests Black Diamond did on older ropes, they found significant weakness at the ends.

“The first test we did was a piece from one of the totally worn-out ends. It broke at around 6 kN—and NOT at the knot.
Yowsa, I had just been whipping all over the place on that cord—and it broke at 6 kN, and NOT at the knot—scary stuff. Though the sporto falls I was taking were super soft (my wife was belaying and is light, and I am fat)—chances are the tension seen in the rope wasn’t anywhere near 6 kN, but if I had gotten slammed hard, low to the ground, etc??? It’s definitely possible to see these kinds of loads in the field.”

Read the whole thing. A commenter on that post made a great point:

Isn't this an excellent argument for us to transition to a Twin or Half rope system?  I have designed mechanical systems for aircraft and from an engineering standpoint I would never be able to justify this in a system.  Yet, I continue to dangle myself from a single rope on a regular basis.  We are so careful building redundancy into our anchors but still have a single point of failure with our ropes.  I would really be interested in the failure rate comparison between half/twin/single rope systems. Would you fly in a plane when you are not sure about the structural integrity of the wing?”


wed wing won said...

i agree, any system is only as strong as it's weakest link (which is usually me)

richard said...

Yeah, but you're pretty neat.