3

Climbing uses specific elastic ropes that absorb the shock from the fall.

I wonder if using static ropes + shock absorber (tear webbing) would achieve the same safety?

P.S.

There are other problems on static ropes, like knot on static rope reduces its strength more than on dynamic rope, and some other problems.

And of course after the first fall you would have to stop climbing, because absorber will be destroyed.

Improve this question
2
  • 3
    One obvious difference is that the elasticity of dynamic rope is uniform - so the more rope that is paid out, the more elongation occurs to keep the forces on the faller pretty much constant for a given fall-factor (in fact, this is exactly why the concept of fall factor is useful).
    – Toby Speight
    Commented Jun 1 at 16:43
  • 4
    Plus - you just ripped your absorber - now what? Could be a bad situation.
    – Jon Custer
    Commented Jun 1 at 18:00

3 Answers 3

Reset to default
5

I do not think this is the same or even comparable. First let us get the obvious out of the way... a dozen shock absorbers are going to kill your budget, and it is a one use item. Once you fall, your shock absorber is broken and has to be replaced.

But regarding the behavior in an actual fall, this is not the same as a ferrata fall or rope access for which the shock absorbers are designed. In a ferrata or rope access, you are attached to a point and fall only onto your absorber. In your case, the absorber protects the topmost quick draw, but you are still attached to a dynamic rope running through that quick draw.
This means that your belayer is getting a pretty hard yank before the absorber has had the time to rip and absorb energy. This creates the problem that the belayer will hit something, but even if we assume there is enough free space, it will definitely not feel the same for the belayer. For the climber, breaking will mostly happen by friction between the rope and quick draws, which will probably make for a pretty long fall, making it likely that the belayer is pulled into the first quick draw and increasing the potential for a ground fall.

Please not that the whole scenario can play out very differently with regard to a number of factors:

  • not all static ropes are created equal, there is semi-static ropes and extremely-static ones. Differences in stretch might seem small, but physics tells us that increasing stretch = breaking distance but just a small bit, we will shave off a lot on the peak force
  • fall factors will play a huge role here
  • friction plays a role. If there is a lot of friction, it de facto increases the fall factor
  • the belay device is likely to have huge influence, something like a Grigri will make things static while an ATC will help making things dynamic
Improve this answer
2

There is at least one major difference between a static rope and shock absorber and a dynamic rope.

At sports climbing with a dynamic rope, falling is more or less a normal use-case. Especially when you climb at higher levels, you will fall frequently.

An industrial climber using a static rope and shock absorber, typically never falls in his entire (work-)life.

Usually when a sports climber falls, then the belayer will just abseil him. However, when you fall into a shock absorber then you may have to call some kind of rescue services. Of course, you have variants in any direction, but let's stick to the defaults.

Just use the equipment for actions for which they are designed.

Improve this answer
1
  • Thanks, I was guessing so. I don't do actual climbing, it's more for safety harness or rappel, falls should be a rare case.
    – Alex Craft
    Commented Jun 14 at 6:43
1

The best answer is unfortunately that you'll find out once you fall.

In theory, a shock absorber of proper dimensions would serve the same purpose as a dynamic rope. After all, that is the concept used both for via ferrata systems and for professional rope access use. The problem is that you must consider the whole system. What is the peak force applied to bolts (or other protection), carabiners and so on? How does the rope (not intended for this use) work in a belay device? If you are climbing a route with fixed protection (bolts), those are (hopefully) placed with the behaviour of dynamic rope systems in mind. Static rope plus shock absorber will behave differently. Will it matter? No way of knowing without testing.

All in all, while it might work, it would mean replacing a system where the risks, though not negligable, are well known with an untested one with yourself as the guinea pig.

Improve this answer
2
  • The shock absorber protects not only climber, but the whole systems - ropes, belays, anchors etc. So, it should be same as with dynamic rope. As you mentioned - the rope access jobs use it all the time.
    – Alex Craft
    Commented Jun 3 at 9:08
  • 4
    @AlexCraft A shock absorber certainly reduces peak force on the entire system, much like a dynamic rope. But not in the same manner. The forces at each point, once friction is considered, will not be the same using a SA at the end of a static rope as using a dynamic rope where extension is distributed across it's entire length. Given a dynamic rope and a SA that extends by the same length, some points will feel a higher load using SA, some using dynamic rope. Will it matter in practice? Who knows.
    – Guran
    Commented Jun 4 at 7:57

Not the answer you're looking for? Browse other questions tagged or ask your own question.