Wednesday, January 06, 2010

Retire Those Ropes

Black Diamond's QC guy, Kolin Powick, has published some scary test results on a rope he had just decided to retire—and those results prompted him to test other old but still-maybe-OK ropes around the BD office. One of the working ends of Powick's trusty 9.4mm broke at just 6 kN of force, and not at the knot. (A figure-eight knot reduces the strength of a rope by around 25 to 30 percent.) That figure compares to a range of around 13 to 16 kN for the new 9.4mm he tested. In subsequent tests, other ropes broke at less than 7 kN—the kinds of forces that can be generated by a short slamming fall. Picture a cliff with an overhang at the bottom and a crux move at the first or second bolt—a very common scenario.

Sure, we all know ropes need to be retired when they start to look old and worn, right? But it's so tempting to hang onto a rope for just a few more pitches. Particularly for sport climbers, Powick's tests should serve as a real-world warning: Sport climbers beat the hell out of the ends of their ropes through repeated falls, hanging, and winching, and sport routes are more likely than most climbs to have crux moves close to the belayer. It's a double whammy.

Bottom line: A hard, unsentimental look at your rope, combined with your personal knowledge of how much work it has seen, is the best guideline for deciding when to retire your cord. Don't be cheap: If it looks bad, it ain't safe.

4 comments:

Craciun said...

so then, the bowline is better than the 8 for tying in?

Clyde said...

Static pulls on dynamic rope don't mean much so this report is pretty much irrelevant. The real question that BD didn't address is how the old rope would handle a drop test. I'd wager that same rope would have still withstood 3 UIAA drops without any problem. Sure it was likely a 6-fall rope when new but it's a very brutal test and surviving 3 in a row would still be fine. A careful examination of your sheath about fifteen feet from each end tells you the most about rope condition.

Clayton said...

According to Sterling, the 8 generates less force than the Bowline:

http://www.sterlingrope.com/media/document/techmanual.pdf

Kim Graves said...

Another reason to use doubles.