Do Screamers Work?

I've dated a few screamers. They worked out great!

For multi pitch ice climbing I carry 1-2 screamers. I place 1 screamer on the first ice screw off the belay, as the BD article states you get the most benefit from the screamer when there is not much rope in service as in right off a belay. As you have more rope in service the effectiveness of the screamer decreases as the rope is going to dissipate the force to a point that a screamer does very little. I do sometimes carry a 2nd screamer that I use on a stubby screw or marginal gear as more of a hail mary as it probably does very little unless it is low on a pitch with not a lot of rope out.

I doubt anybody can find a case where a screamer increases peak force on protection.

Scott McMahon wrote:I've dated a few screamers. They worked out great!

Funny comment, but that shit gets old after a while.

Rick Blair wrote: Funny comment, but that shit gets old after a while.

What you don't like levity? It's only Wednesday brother.

Scott McMahon wrote: What you don't like levity? It's only Wednesday brother.

I was talking about the screamer.

Eric Moss wrote:I doubt anybody can find a case where a screamer increases peak force on protection.

The CAI tests found that some of the time.

Eric Moss wrote:I doubt anybody can find a case where a screamer increases peak force on protection.

You may doubt or believe what you wish but people have. Smart people with a lifetimes experiemce testing equipment. We did as well:-)

Eric Moss wrote:I don't see how fall speed affects activation force. It's not as if the screamer gets shock-loaded.

However they are suprisingly speed sensitive. Most things are. The reasons why are complicated but well identified.

Where?

Eric Moss wrote:Where?

Padua

I mean, in what publication are these factors identified?

Jim and other science guys out there, I have a related question.

If the deceleration was smoother in nature, would it help? I'm thinking a trampoline spring or section of really heavy bungee cord (with a long sling to provide a maximum extension distance).

It's certainly not as practical as using a sewn screamer. The question is, would it produce better (or worse) peak loads?

Eric Moss wrote:Perhaps dampen is a better word. Screamers don't significantly change fall energy into heat/light/sound or kinetic energy, which is what I would consider energy dissipation.

Damping, by its very definition, changes kinetic energy into "other" energy (usually heat). Damping is energy dissipation, that's its entire purpose.

I understand you have good intentions, but your understanding of the topic seems sufficiently lacking to warrant some constraint with regard to commenting on it.

Kyle Tarry wrote: Damping, by its very definition, changes kinetic energy into "other" energy (usually heat). Damping is energy dissipation, that's its entire purpose. I understand you have good intentions, but your understanding of the topic seems sufficiently lacking to warrant some constraint with regard to commenting on it.

When should one use a screamer? When should one not use a screamer? Where should one place the screamer? Why?

Eric Moss wrote: When should one use a screamer? When should one not use a screamer? Where should one place the screamer? Why?

I don't know the answer to these questions. But after watching you get schooled in this thread, and in the thread about stoppers in horizontal cracks, I know that you don't know the answers either.

That is why I ask. Welcome to the conversation.

"When should one use a screamer? When should one not use a screamer? Where should one place the screamer? Why?"

Well, I don't know anything about it, but there seems to be a pretty consistent set of answers to these questions from the people who sound like they know what they're talking about:

1. use a screamer when you anticipate a short fall, even if it's high fall factor, but don't expect it to make a huge difference to the maximum impact force. Don't use it if you can't afford to fall the extra distance (say ledge/ground in the way).

2. don't use one for a long fall, regardless of fall factor.

3. To zeroth order, one can consider a screamer to remove a certain amount of energy from the fall before the fall is caught normally after the screamer has finished ripping. A short fall (regardless of fall factor) results in a small amount of kinetic energy, so the screamer can hope to absorb a substantial fraction of it. The energy of a climber in a long fall is high enough that the screamer will not absorb a substantial fraction of it. Furthermore, apparently it has been shown in testing that a screamer rips under a smaller force if it is loaded at high speed. If it rips at a force less than twice the weight of the climber (ignoring friction), then the climber continues to speed up as the screamer rips, meaning that the ultimate impact force will be higher. In no case in testing, did it make a very big difference one way or the other. Obviously there is more to consider than just the maximum impact force - if having a screamer causes you to deck on a ledge before you get caught, that sucks.

Eric Moss wrote:That is why I ask. Welcome to the conversation.

Bullcrap. I've been watching your posts for three days, ever since you arrived. You make grand pronouncements like "entirely untrue," and "you're wrong about everything else" to some of the most knowledgable posters around. You deploy technical jargon you barely understand. Then you get schooled. You're not just trying to learn; you're arguing from ignorance.

Eric Moss wrote:Screamers don't dissipate energy, they increase the time that the anchor imparts skyward force on the system, thus decreasing kinetic energy of the fall.

Eric Moss wrote:Screamers don't significantly change fall energy into heat/light/sound or kinetic energy, which is what I would consider energy dissipation.

Eric Moss wrote:The answer is: yes, if in doubt, use a screamer. Addressing the consideration that a screamer could be counterproductive: it is possible to build a screamer that would be counterproductive if it cannot do work (F*d) greater than the additional energy of the extra fall distance (an example would be a screamer that unravels under body weight), but obviously screamers are stronger than this so that they are productive.

Eric Moss wrote:Entirely untrue.

But then...a sudden change!

Eric Moss wrote: That's a good point. Hadn't thought of that.

Eric Moss wrote:I guess the screamer does dissipate energy to the earth, so I was wrong to avoid that terminology. Anyway, assuming the energy absorbing capability of a screamer is only on par with the energy added by lowering the anchor point, brenta has pointed out that rope will be on the climber side that would otherwise be on the belayer side. Isn't this a better situation because the rope can stretch more?

But...

Eric Moss wrote:I doubt anybody can find a case where a screamer increases peak force on protection.

rgold wrote: The CAI tests found that some of the time.

And from another thread...

Eric Moss wrote:You're right. It is secant. You're wrong about everything else.

Eric Moss wrote:You say the force calculator should use the ideal spring model, but not use static elongation. This seems contradictory. Also, you're not addressing the worst case scenario here. Are you seriously endorsing this stopper configuration as a general practice?

Eric Moss wrote:I realize now that peak force on the anchor only occurs after the rope has finished stretching. This implies that the force on the anchor and the friction between the cables will gradually build, allowing for the tension in each strand to equalize. Given that there is length in the stands to equalize tension and barring binding that would prevent equalization, I think rgold's estimate will prove to be quite accurate. Thank you, rgold.

Try not to be so damn sure about things you don't know anything about.

Eric Moss wrote: When should one use a screamer? When should one not use a screamer? Where should one place the screamer? Why?

The behavior of screamers is pretty well documented, in the BD report and elsewhere. As per that report, they can reduce the peak force ~20%, depending on the situation. So, use them in similar situations, where you think that ~20% reduction in fall force will be beneficial. One can't enumerate the exact situations when this is, but questionable pieces of protection and relatively short falls seems to be the right context.

I do not intend to get engaged in a discussion about when to use screamers, because it has already been discussed ad nauseam, here and elsewhere. I was simply pointing out that you don't seem to understand the very terms you were using while debating with others. As I said, "your understanding of the topic seems sufficiently lacking to warrant some constraint with regard to commenting on it."