Came across this on the DMM website. Drop tests of 11mm Spectra vs 16mm nylon both with and without overhands in the slings. Quite a few of the tests snap the slings. Granted we don't usually take factor 1 or 2 falls onto static slings (does FF even apply to static?, I guess so) but it still makes you think...

www.dmmclimbing.com/news.asp?nid=293&ngroup=1

There's a link in the article to a video of the tests. Cool vid.

Clayton

Very interesting and informative video. Thanks for posting.

Agree. Interesting stuff. That's why I posted this thread: www.mountainproject.com/v/general_climbing/dmm_video__dyneem>>>

:)

1 - That's a correct thought to get into. No, ff should not apply to static systems.

2 - What does this test make you think about? In other words, what about this test makes it exaggerate a result when applied to a real world situation?

Try this thought -- keep the slings only, don't introduce the rope. Why would the result be exaggerated from the DMM test as compared to a climber on the wall?

The basic thought is that when you move to a static system, the FF does not correctly indicate how severe a fall can be.

When you're climbing, it's a good ballpark to measure rope in service, protection intervals, etc; you can take a fairly large fall away from the anchor, and not really translate much force as the rope will take it, along with you and the belayer. You'll get a fairly linear result chart using the same rope & climber, changing FF -- it works pretty well with a dynamic rope. If you counterbalance, run a dynamic belay, or both, even less force will result.

With a static system, what matters mass acceleration to a sudden deceleration; also mass composition as well as amount & fall distance. Why does this not matter with those small anchor tie-in falls? You simply don't fall enough distance and your body takes the hit. Not saying it probably won't hurt like hell, it will; but failure -- what you need are more like 2-3 meter static drops, then components start failing (provided fatigue in materials hasn't already been measurable). With a static system, think of everything as FF 2.0 -- then rely more the distance of the fall and what kind of a mass you're dropping; maybe that would help better.


But the same, don't get me wrong, I'm not belaying any leader with the potential using static slack for my tie-in -- I'm using the dynamic rope and keeping myself taught to the anchor; I mean you'll get jacked otherwise, but the thoughts discussed here are about system integrity and measuring how severe the small fall would be.


Think of an aid climber, they aren't blowing the team off the wall everytime they forget to keep the climbing rope as their main catch and land on their daisy to that single nut. It still hurts like hell, but things aren't exploding (like I said, unless you already have fatigue -- or the placement/rock is sketch).

I saw tons of this kind of stuff BITD with Bouchard/ Wild Things. The results, true are not applicable to real loads, but sobering the same.
Anything CAN break, but in reality, gear is pretty strong.

Okay, I see what you mean now. Thanks.

The knotted nylon actually absorbed more force in fall factor one than a strait sewn nylon sling. Would multiple knots absorb enough force to create a poor man's via ferrata style load limiting anchor? I would be interested to see how much impact force is absorbed by 10 or 12 knots.

I really like the video.

I would like to see that done for a daisy chain (nylon and Dynema) and the metolius PAS. My guess they would both break on a FF2 and the daisy would break on a FF1.

A daisy should have the same strength as an open loop of the same material, no? Maybe more because you have to rip each loop before you can rip the final bar tack.

Still, I never use a daisy for a belay anchor. And if I do clip in with one, I never clip one of the intermediate loops and the end simultaneously...if that one intermediate loop goes your no longer attached to anything!

believe it or knot, the thoughts of the anchor tie-in were dropped; and stuff failed at short falls, especially the PAS; -- so you think wtf, this tie-in sux.

But really, it makes sense, if everything is static, something will fail with measurable sudden deceleration -- the energy has to go somewhere; then the thought of the mass composition comes in and wavelength to energy. That's why these results come in way high and you see stuff fail as compared to what climbers are going to actually encounter.

The trouble is people take the small fall that doesn't really measure to very much and think it will translate to blowing apart a good load distributing anchor or a climber's tie in. Which isn't accurate when you're out climbing unless something like perceived solid pro is actually marginal pro, it's rigged at bad angles, or you've got a tie-in that is improper/poor condition such as 2-loop short clipping a daisy with the same biner.


Overall, if you have equipment in good order/no measurable fatigue, with good protection placements, distributing at good angles, you really need to have the 2-3 meter static drops to see system failures, which will be the knot or biner on the mainline, the anchors are actually testing better than the mainline. But this won't prevent injury to you, this is just system integrity.

Using a dynamic rope (in good condition as well) and your attentive belayer, you basically solve your injury problems that come from energy as long as you don't hit anything on the way down.

Mark asked, "what does this test make you think about?"... aid climbing and better ways to transfer weight and get onto the top piece (when suspect) without risking the 2 - 4 foot static fall onto the previous piece. Seems like the answer is to leave the rope clipped to the last and clip one daisy into the top piece with the ladder while step testing and then unclip the lower piece daisy (leave the step if still useful) until you are fully onto the high piece and then move up the lower step. but then again, I'm still an aid newB so I might find out the error of my ways while whipping before too long :) live and learn.