A_Little_Off_Route Posted December 10, 2004 Share Posted December 10, 2004 I've been thinking about this idea for a while but can't seem to wrap my brain around the exact physics of it. It seems like a really good idea but I defer to y'all now. Imagine you are anchored to the ground belaying your partner (a solid 5.9 leader) on lead up a 5.12C above you because he is "Off_Route". You have a locking biner with your stich plate, grigri, ATC etc clipped to your belay loop as normal. Your parner flirts with a fall above... My idea is: instead of clipping your atc through a locker straight to your belay loop what about clipping it to one end of a screamer and the other end to your belay loop via another locking biner. My theory is that as your parner takes a whipper and you brake the belay the screamer would activate and absorb 2-5kn of the fall. My question is: does absorbing 2-5kn at the belay translate to a useful reduction is forces at the top protection piece (which is really where we want to reduce forces). I know that a belayer jumping up can reduce forces in a fall, and I figure this would be simmilar, but I never really undestood how that worked. If it works it would be a way to make every belay safer by only adding one screamer instead of one at each piece as is traditionially done. The big problem I see is as it activates your belay plate is now 12" further from your loop. A non issue for gri-gri users but might be an issue for more traditional belay plates. What do you think? A_Little_Off_Route Quote Link to comment Share on other sites More sharing options...
DavidHiers Posted December 10, 2004 Share Posted December 10, 2004 Sure, it'll work. Since F=ma, and a has units of distance/time^2, stretching out the time for the system to stop the fall always reduces the impact load. Mobile belayer and running out a bit of rope will add time, just like a screamer. Imagine the limiting case of stopping the fall in infinite time. You'd kill the leader, but you'd never pull the top piece! I suppose the perfect device would be some kind of smart brake that would (1) instantly activate and (2) gently slow the fall over the maximum distance permitted by the situation, slowing decelerating the leader to a graceful stop at exactly ground level. There may be practical considerations that make it a Very Bad Idea, but the theory is sound. Quote Link to comment Share on other sites More sharing options...
Dru Posted December 10, 2004 Share Posted December 10, 2004 The vibes from the screamer ripping may be enough to either cause you to let go of the belay, or cause an auto locker like a GriGri to not lock. Not to mention the sudden ripping as your device moves away from you. I think it is silly. Quote Link to comment Share on other sites More sharing options...
cracked Posted December 10, 2004 Share Posted December 10, 2004 If a screams rips at 2kN, it won't rip on a typical fall. I weigh about 1kN, and am rarely yanked up when a partner falls. So typical force on a belayer is significantly less than 2-5kN. Quote Link to comment Share on other sites More sharing options...
Squid Posted December 10, 2004 Share Posted December 10, 2004 (edited) I'm trying to visualize this (stopping a whipper with a grigri tethered to a screamer), and the only image I get is the grigri taking out my remaining teeth. ..and as Cracked points out, I can't imagine what situation would generate those kind of forces on the belay device (factor 2 falls only?) but then again, I'm a pessimist. Edited December 10, 2004 by Squid Quote Link to comment Share on other sites More sharing options...
ketch Posted December 10, 2004 Share Posted December 10, 2004 Cracked, you can't weigh a Kn one is mass and the other is force. But you are right about the force. By the time a force of the fall is translated through the top beiner and the other protection, the belayer doesn't see a large force (sometimes). I have had leaders fall on ropes with a heinous rope path where I barely felt the fall. I don't think that a screamer would help unless the path was real clean, and even then it would be of limited assistance. Quote Link to comment Share on other sites More sharing options...
Alpinfox Posted December 10, 2004 Share Posted December 10, 2004 These things would allow the force to be more distributed to multiple pieces of gear and the belayer. They cost $25 each though. The only screamer I rock climb with is Squid. Fun armchair speculation problem though. Quote Link to comment Share on other sites More sharing options...
cracked Posted December 10, 2004 Share Posted December 10, 2004 Cracked, you can't weigh a Kn one is mass and the other is force. But you are right about the force. By the time a force of the fall is translated through the top beiner and the other protection, the belayer doesn't see a large force (sometimes). I have had leaders fall on ropes with a heinous rope path where I barely felt the fall. I don't think that a screamer would help unless the path was real clean, and even then it would be of limited assistance. Weight is a force. W=m*g. High school physics anyone? I weigh 0.947795596kN. I once gave ashw_justin a few feet of inadvertent penalty slack because when his skinny ass dropped on the rope it felt like he was pulling up slack. Quote Link to comment Share on other sites More sharing options...
Alpinfox Posted December 10, 2004 Share Posted December 10, 2004 I weigh 0.947795596kN. That is only true assuming you are at some point in the earth's gravitation field where g = 9.8m/s*s which is just an AVERAGE after all. Cracked, with one of those roller-biners and a few dozen bottle rockets strapped to your fat ass you might get jerked off the ground when belaying someone. Wouldn't that be a treat? Quote Link to comment Share on other sites More sharing options...
cracked Posted December 10, 2004 Share Posted December 10, 2004 Go pick on someone your own size (RuMR maybe?), Pax. We don't want anyone getting hurt. Quote Link to comment Share on other sites More sharing options...
Alpinfox Posted December 10, 2004 Share Posted December 10, 2004 As someone said recently, "I kid because I love". Peace to the big boys. p.s. Hey Off_Route, Welcome to cascadesprayers.com! Quote Link to comment Share on other sites More sharing options...
cracked Posted December 10, 2004 Share Posted December 10, 2004 Quote Link to comment Share on other sites More sharing options...
bigwalling Posted December 10, 2004 Share Posted December 10, 2004 Forget this shit, seems like a real bad idea! I've used a screamer at the belay when I solo, seams like a good idea when the belay sucks. Quote Link to comment Share on other sites More sharing options...
RuMR Posted December 10, 2004 Share Posted December 10, 2004 If a screams rips at 2kN, it won't rip on a typical fall. I weigh about 1kN, and am rarely yanked up when a partner falls. So typical force on a belayer is significantly less than 2-5kN. Liar...you are at least 2 metric tons...this has been an established fact for well over a year now...piggie piggie Quote Link to comment Share on other sites More sharing options...
treknclime Posted December 10, 2004 Share Posted December 10, 2004 What does Yates say about it?? Could be the indirect force of the releasing bar tacks ("if" the force is strong enough), could cause stuff to walkout, release, reposition, or ?? Maybe mid-way pro would drop out, leaving only the top one? Wonder if some testing has been done to test out the idea?? Quote Link to comment Share on other sites More sharing options...
Dru Posted December 10, 2004 Share Posted December 10, 2004 They don't bar-tack them anymore. Bar-tacked Screamers sucked, but they were only sewn that way in the early to mid 90s. Quote Link to comment Share on other sites More sharing options...
cracked Posted December 10, 2004 Share Posted December 10, 2004 If a screams rips at 2kN, it won't rip on a typical fall. I weigh about 1kN, and am rarely yanked up when a partner falls. So typical force on a belayer is significantly less than 2-5kN. Liar...you are at least 2 metric tons...this has been an established fact for well over a year now...piggie piggie Don't hate me because I'm perfect, Rudy. Quote Link to comment Share on other sites More sharing options...
RuMR Posted December 10, 2004 Share Posted December 10, 2004 yeah...perfectly round Quote Link to comment Share on other sites More sharing options...
Jason_Martin Posted December 14, 2004 Share Posted December 14, 2004 The best thing to do is to use your equipment properly. In other words, don't mess around with manufacturer recommendations. Use things the way they were designed to be used. Belay off of your belay loop with a belay device and all will be well... Jason Quote Link to comment Share on other sites More sharing options...
chucK Posted January 3, 2005 Share Posted January 3, 2005 If you're using a dynamic rope, then you won't need a screamer attached to your belay device. Quote Link to comment Share on other sites More sharing options...
JosephH Posted January 3, 2005 Share Posted January 3, 2005 They don't bar-tack them anymore. Bar-tacked Screamers sucked, but they were only sewn that way in the early to mid 90s. Yeah, they are stitched along the length now. We used Air Voyagers in the mid 80's and on one climb called the Wizard at Crow Hill we blew out a whole bunch of them taking wingers off of it onto either an original #1 Friend or before that a circle of equalized brassies. The bar tacks typically blew pretty violently so we'd diagonally and progressively pre-slice the first 5-6 of them insure equalization would have a chance to occur on the web of brassies. Our falls typically blew between 14-20 bars. When roped soloing you should always have one at your [belay] anchor, but I can't think of anytime it would be necessary, desirable, or a good idea to have one between you and your belay device - it would just add a lot of unpredictability to the belay. As I said, they tend to go off loud and fast. Quote Link to comment Share on other sites More sharing options...
nomad Posted January 12, 2005 Share Posted January 12, 2005 The best thing to do is to use your equipment properly. ... don't mess around with manufacturer recommendations. Use things the way they were designed to be used. Oh come on, where's the fun in that. I will continue to proudly open my beer with a biners and self arrest with my nut tool. Quote Link to comment Share on other sites More sharing options...
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