Do Screamers Work?

Here's to hoping Eric doesn't need similar reassurances when dating or marrying. Those numbers are equally hard to come by and reliable / reproducible testing methodologies are very difficult with women. I personally struck gold in the wife department twenty-one years ago, but then there's almost nothing I can't get right on the third or fourth try...

I believe two screamers in parallel might provide sufficient tear resistance to prevent an increase in peak force on protection in the scenario in question. And if not two, then three or more would be enough (as a trivial case, the tear resistance could be greater than the protection strength).

Perhaps in general, when placing a screamer on a lead anchor, one should aim to use the most screamers that will together have tearing strength less than the strength of the anchor.

Eric Moss wrote:I believe two screamers in parallel might provide sufficient tear resistance to prevent an increase in peak force on protection in the scenario in question. And if not two, then three or more would be enough (as a trivial case, the tear resistance could be greater than the protection strength). Perhaps in general, when placing a screamer on a lead anchor, one should aim to use the most screamers that will together have tearing strength less than the strength of the anchor.

Might as well not use them at all rather than do that for any placement with any marginal aspects to it at all. And, personally in my use of screamers, I'm typically much less interested in peak load and way more in how and over how much time a placement gets loaded given most pro needs to 'seat' as part of the process.

Somehow I can't shake the impression you're way overthinking most aspects of trad protection with regard to attempts to apply math to the whole affair. Math can inform design, execution and testing in manufacturing, but out on the rock it's of little real value compared to intuition and common sense. And people have somehow been climbing without it for like, well, forever.

Healyje wrote: Might as well not use them at all rather than do that for any placement with any marginal aspects to it at all.

This is the same as saying that screamers don't work, which is obviously untrue.

You think I'm over-analyzing? Let me correct you: I'm analyzing, you are not analyzing.

Healyje wrote: Might as well not use them at all rather than do that for any placement with any marginal aspects to it at all.

As with everything screamer related, putting two in parallel would be scenario dependent. If you're clipping a #1 nut rated for 2kN, it's not a good idea. If you're clipping a fixed pin out of the belay on El Cap, it might be advantageous.

The activation force of two in parallel would be about 4kN which is still less than the rating of any piece designed to stop a lead fall. The UIAA minimums for cams are 2kN for aid and 5kN for free climbing/ lead pro. If you're using something rated for less than 5kN to actually keep you off the deck, you're really playing against the odds. If the gear is truly that bad, maybe it's better to reconsider whether it's a good idea to climb the route in the first place.

20 kN wrote: If the gear is truly that bad, maybe it's better to reconsider whether it's a good idea to climb the route in the first place.

That is my how I approach trad climbing. Although the list of climbs I want to do but I'm too scared to do is getting bigger everyday.

20 kN wrote:If you're using something rated for less than 5kN to actually keep you off the deck, you're really playing against the odds. If the gear is truly that bad, maybe it's better to reconsider whether it's a good idea to climb the route in the first place.

Did you just describe modern A4+ and A5?

Eric Moss wrote: This is the same as saying that screamers don't work, which is obviously untrue. You think I'm over-analyzing? Let me correct you: I'm analyzing, you are not analyzing.

You stated you "believe", that´s not analysing.
I´m with Joe here, you ARE overthinking it all and in reality anyone who f*cks about fitting two screamers to a marginal piece instead of just climbing further deserves what they will get. Marginal pieces are just that and you can´t calculate how strong they are, they are phsycological crutches not real protection.
Screamers work to a limited extent in particular circumstances, they don´t work in others.

Jim Titt wrote: You stated you "believe", that´s not analysing.

It's called a hypothesis, Jim. Get with the program.

Eric Moss wrote: It's called a hypothesis, Jim. Get with the program.

You know what you do with a hypothesis? You test it. Now get with the program.

Eric Moss wrote: It's called a hypothesis, Jim. Get with the program.

A belief is not a hypothesis.
At this point I'm compelled to wonder - what is the point of your various posts/threads trying to quantify safety for things that really don't lend themselves to that analysis? Are you really going to stop mid-pitch and calculate how you can eke out an extra 0.2kN from the piece you're placing?

Eric Moss wrote: It's called a hypothesis, Jim. Get with the program.

I´d call it a wild guess.

20 kN wrote: As with everything screamer related, putting two in parallel would be scenario dependent.

A piece which can sustain two screamers in parallel, doesn't need screamers.

Healyje wrote: A piece which can sustain two screamers in parallel, doesn't need screamers.

Not necessarily. Consider a small stopper or pin that's placed out of the belay. It might hold, maybe, 7kN. Say this theoretical small piece was a placement 10' off the belay and it was the last solid piece before 30' of hard aid with no good gear in sight. Taking a fall in the middle or end of this theoretical hard aid section would cause a fall factor of over 1, which would be enough to snap a piece rated for 7kN. Placing a single screamer wouldn't do enough with a fall that large and a fall factor that high, and so placing two would probably be more advantageous in that situation.

Screamers are a fixed solution in a variable world, which is why they arnt that useful. For a screamer to truly be useful in all situations, you need to be able to adjust the activation force and energy dissipation level. If the fall factor and fall distance is too high and the activation force too low, it wont reduce the peak load, and it can actually increase the peak load. On the other hand, if the activation force is too high, they wont work on marginal placements. That's the problem. They are only truly useful in a limited range of scenarios, all of which involve small lead falls with low amounts of energy, but people tend to market them as being universally useful for any placement which you dont trust fully, no matter how big of a fall you might take on it.

I stand by the 'doesn't need it in the first place' statement and there's just no scenario or use-case I can imagine where two screamers in parallel would have any utility whatsoever and I've blown through a lot of screamers and am pretty good at finding novel ways to use them.

In the end it's just another ROI / risk-reward deal not unlike the decision to stay and mess with a finicky placement or just climb on and hope for something better - I fail to see any real benefit in this use-case and this again strikes me as a case of way over-thinking things.

I try to keep things simple and fast once I leave the ground despite the fact that I use a lot of what some might consider 'intricate' and / or marginal pro. But even in those instances I'm constantly weighing the ROI, making relatively snap judgments of worth, and trying to so as far ahead as I can. Placement have to justify themselves in my mind and I either get an quick intuitive buzz to that effect or I don't. If I do, then I have the skills to execute reasonably fast and will blow on by if not.

My point being it's not necessarily just about the technicality of an individual placement out of context from the entirety of the endeavor, it's a matter of contribution - what does a placement contribute to the overall rope system and is it worth it in that context while the clock is burning down. In that context, any piece that can sustain two parallel screamers is already way good enough for me.

In a nutshell, the problem I have with all this kind of physics / engineering thinking is it just has little to no utility on lead and the technical minutiae of any given kind of pro is similarly worthless at the sharp end when I'm staying out of my head and operating intuitively. And any time I've felt I was in my head to that degree my second foot has never left the ground and I've just split the crag and done something else more amenable to that mindset.

P.S.

20 kN wrote:For a screamer to truly be useful in all situations, you need to be able to adjust the activation force and energy dissipation level.

I agree and that's why I always have a razor blade around when I anticipate using them and variously pre-slice them to adjust the activation curve on marginal gear, but that again requires a good intuitive feel for what you're doing.

Healyje wrote:there's just no scenario or use-case I can imagine where two screamers in parallel would have any utility whatsoever

See 20KN's post above. He/she is correct that there are indeed scenarios where two screamers in parallel should be used.

It is not true, however, that screamers only work in small falls. Dan Osman used screamers in his rope jumps.

Eric Moss wrote: It is not true, however, that screamers only work in small falls. Dan Osman used screamers in his rope jumps.

Well they will deploy in any fall large enough to trigger them, but whether they "work" I supposed depends on what your goals are. Screamers only remove a fixed amount of energy from the fall. However, the amount of energy in any scenario is of a variable nature. Every step you take above your last piece increases the amount of energy that needs to be displaced should you fall until you put your next piece in. It's easy to see how this works with some roundabout example math.

A standard screamer probably removes somewhere around 1000J of energy, and adds maybe a few hundred as a result of extension. So we will call it a net removal of 700J. If you're only a few feet past the last piece, you fall and say your system needs to displace 2500J of energy, your screamer will remove about 28% or so from the system. On the other hand, if you're a few body lengths above the last piece and fall creating say 18,000J of energy, the same screamer will still only be able to remove 700J (possibly even less because screamer dont respond as well to very fast tearing of the stitches), or just under 4%. Whether that's worth it to you or not is your decision, but most people would call that ineffective, especially a considering a dynamic belay can reduce the impact force by several times that. The other issue is the amount of energy a screamer adds to the system depends on the fall factor. The higher the fall factor, the more the screamer will add to the system as a result of extension.

Maybe I just need to take my 550Hz load cell out to the crag and take some whips on some screamers and a control, then post the graphs to MP. That might help give some more detail into the issue. If anyone wants to send me some, I'll test them. I have four I can throw in for testing.

Maybe Dan Osman isn't really the best example to cite for screamer effectiveness...

If Alex Honnold used screamers to butter his bread, would that mean screamers aid digestion?

Eric Moss wrote:It is not true, however, that screamers only work in small falls. Dan Osman used screamers in his rope jumps.

As part of a highly calculated, extremely complex anchoring system that has no relevance to real world climbing.

20 kN wrote: The higher the fall factor, the more the screamer will add to the system as a result of extension.

I think this is half true. I think extension in itself adds the same amount of energy regardless of the fall (assuming equal extension). I think the reason screamers end up being counterproductive at a point is not because of this additional energy from extension, but rather because the action of the screamer undermines the dynamic belay. In other words, because the screamer is softening the fall, it deprives the belayer the opportunity to soften the fall.

It would be awesome if you did some tests and I'd love to see the results!