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stymingersfink
Jun 26, 2008, 4:23 AM
Post #26 of 39
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skelterjohn wrote: In reply to: You're on the right track. It's not that the gear would take 2x the force. The force will be the same but what most people overlook is the effect of time. The force generated by a falling object remains constant. For climbers the relevant change is in the dissipation of those forces. That's to say that when a climber is arrested in half the time, the PEAK impact force is raised, although TOTAL impact force will remain constant. You are confusing force and energy. The total energy that needs to be dissipated depends only on fall distance. The longer the distance between where the gear catches you and stops you, the less the average force is. F = E*d. No, you forgot about the mass of the falling object. 100kg falling 10meters would generate far less "total energy that heed to be dissipated" than 200kg falling the same distance. Let's not argue physics here though. They do enough of that in the Lab.
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dingus
Jun 26, 2008, 4:36 AM
Post #27 of 39
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mtnfr34k wrote: dingus wrote: I have 8.1 doubles rated as twins and have almost always clipped them as twins. They're kinda way stretchy in double mode. But twin mode is so much less hassle, for the leader and belayer (and rope management in general) DMT Off-topic, but who made those ropes? I'm looking for a pair of ropes that I can use as twins most of the time but as doubles when rope-drag is an issue. Thanks Chris Mine are Black Diamond. Hold on lemme go look: Sorry the end taks are soiled and unreadable. There gettin up there in age now. I've only used em for mountaineering and ice climbing so they don't see consistent use all year long. I'm not sure who made BD ropes - PMI maybe? I think this rope is the grandchild of the ones I have: http://www.justropes.com/.../item.asp?itemid=132 and here's one slightly thicker, still dual rated and on sale to boot [urlhttp://www.justropes.com/shop/item.asp?itemid=134 DMT
(This post was edited by dingus on Jun 26, 2008, 4:48 AM)
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paulraphael
Jun 27, 2008, 4:32 PM
Post #28 of 39
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Most double ropes made today are rated to be used as twins. I was skeptical of the practice; common sense suggested it would double the impact force. But my common sense was wrong; calculations done by people in the Lab show that impact force is increased by much less than 100% when you fall on two ropes instead of one. Drop tests (reported on Will Gadd's blog, I think) bear this out. To be extra safe, follow the manufacturer's recommendations. But if you're not sure what those are, add 50% or so to the impact force rating of your half ropes and see if the number's still acceptable. In most cases the actcual increase should be even less than that.
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pipsqueekspire
Jun 30, 2008, 4:48 AM
Post #29 of 39
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I actually called BD about the 8.1 Beal ropess use as twins. I saw it said on the website that they were rated for both. But I wanted to double check since the marking was clearly a double rope. So I called and they said "Oops- let me delete that right away- they are rated ONLY as doubles." SOOOO...... the real question is why did you buy doubles? If you dont trust them to hold you why did you get them?? More importantly I use doubles to alpine and ice climb- Alpine for the light weight full length raps and meandering routes and protection from rockfall. Why carry screamers if you have a low impact rope RIGHT ON YOUR HARNESS!!! Ice climbing for the LOW IMPACT on a screw. Are you clipping bolts with your doubles and yelling for a "soft catch"?? Just a thought pip
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stymingersfink
Jun 30, 2008, 12:06 PM
Post #30 of 39
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pipsqueekspire wrote: I actually called BD about the 8.1 Beal ropess use as twins. I saw it said on the website that they were rated for both. But I wanted to double check since the marking was clearly a double rope. So I called and they said "Oops- let me delete that right away- they are rated ONLY as doubles." SOOOO...... the real question is why did you buy doubles? If you dont trust them to hold you why did you get them?? More importantly I use doubles to alpine and ice climb- Alpine for the light weight full length raps and meandering routes and protection from rockfall. Why carry screamers if you have a low impact rope RIGHT ON YOUR HARNESS!!! Ice climbing for the LOW IMPACT on a screw. Are you clipping bolts with your doubles and yelling for a "soft catch"?? Just a thought pip I climb a fair amount of ice in the winter, using the Beal icelines whenever a rope is necessary. I rarely if ever utilize screamers, in fact if any are to be used they are the ones from my partners rack, as mine sit in my stash of aid climbing gear. Occasionally, when the ice is crap, I might feel the need to use the screamers, but for the most part I clip my ice screws with sport draws, relying on skill to not fall and super stretchy ropes in the unlikely event that skill fails me. On the one occasion I've caught a fall taken while climbing ice, it was plenty soft, even for the 30 footer it was, caught on a single 8.1mm iceline. Luckily it was on vertical ice, so no damage to the leader, other than a bruised ego.
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dingus
Jun 30, 2008, 2:59 PM
Post #31 of 39
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pipsqueekspire wrote: I actually called BD about the 8.1 Beal ropess use as twins. I saw it said on the website that they were rated for both. But I wanted to double check since the marking was clearly a double rope. So I called and they said "Oops- let me delete that right away- they are rated ONLY as doubles." SOOOO...... the real question is why did you buy doubles? If you dont trust them to hold you why did you get them?? More importantly I use doubles to alpine and ice climb- Alpine for the light weight full length raps and meandering routes and protection from rockfall. Why carry screamers if you have a low impact rope RIGHT ON YOUR HARNESS!!! Ice climbing for the LOW IMPACT on a screw. Are you clipping bolts with your doubles and yelling for a "soft catch"?? Just a thought pip I already said why I bought them. I already said I clip them as twins the vast majority of the time. I've been using an 8.1 doubles config for more than a decade. The ones I bought were rated as doubles/twins. I've fallen on them numerous times. They work for me just fine. I use screamers as I see fit. Feel free to do whatever your heart desires. Have a great life. DMT
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pipsqueekspire
Jul 1, 2008, 2:34 AM
Post #32 of 39
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Sillly Dingus- you have the correct ropes for this..... the OP was asking about DOUBLES used as TWINS. Silly climbers can't read... have a nice day. Just a thought -pip
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stymingersfink
Jul 1, 2008, 3:13 AM
Post #33 of 39
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pipsqueekspire wrote: Sillly Dingus- you have the correct ropes for this..... the OP was asking about DOUBLES used as TWINS. Silly climbers can't read... have a nice day. Just a thought -pip Speak for yourself. He was giving a first-hand account of his use of doubles as twins.
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pipsqueekspire
Jul 1, 2008, 3:48 AM
Post #34 of 39
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dingus wrote: The ones I bought were rated as doubles/twins. Silly climbers can't read- yet again.......
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bradley3297
Jul 1, 2008, 4:44 AM
Post #35 of 39
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Registered: May 5, 2008
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AMEN> GOD DAMN> retard advice i swear.only use twin ropes for twin system. asking for trouble otherwise
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stymingersfink
Jul 1, 2008, 6:10 AM
Post #36 of 39
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bradley3297 wrote: AMEN> GOD DAMN> retard advice i swear.only use twin ropes for twin system. asking for trouble otherwise mostly agreed, though if Dingus says he's been using a doubles-->twin system for quite some time with no major fuck-ups, I'll take it as gospel that it CAN be done safely, as long as you ain't a donny (which in most cases is not the case). MARK IT ZERO!
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dingus
Jul 1, 2008, 6:30 AM
Post #37 of 39
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Yall best heed your sticker warnings and your labels. That's the best advice I can give you. I gave the appropriate links to the OP. There really isn't anything to add. DMT
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healyje
Jul 1, 2008, 9:28 AM
Post #38 of 39
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Except maybe that there's a lot of damn panty knotting going on. The only three hard and fast rules I have about such matters is: a) Don't use twins as doubles (unless dual rated as doubles) b) Don't use a double as a single (unless dual rated as a single) c) Don't use singles as twins (unless dual rated as twins) Beyond that, over the years I've used and fallen on all manner, kinds, and sizes of single-rated ropes used as doubles and twins from 11's down to 9.8's and even combos such as 9.8/10.2 and 10/11. Is it worth making sure your pro is either solid or screamered? Sometimes. Sometimes I don't care. Sometimes in FA territory where the rock fall potential is very high, or the rock is really sharp, I just want beefier ropes used as doubles or twins and I don't care the fall is going to be harder, or even possibly hurt a bit - oh well, at least I'll stop. Maybe I'll beef or double up a placement under these circumstance, often I won't as my normal placements are usually pretty bomb this many years on. Sometimes I go out the other way and pre-slice screamers on an angle for a more gradual loading profile on really marginal gear that would normally only be considered aid placements. But typically those placements are marginel regardless if the ropes are being used within perfectly within manufacturer's parameters. All in all, I consider discussions like this to be occuring within the margins of gear that's so good these days as to border on 'over engineered' (not that it's really possible to do when talking about some of today's ultralite gear, however). But from an old guys perspective, it's really a nitpicking, 'tempest-in-a-teapot' sort of discussion. And Dingus has been mangled in enough interesting and unique ways on and off rock, and climbed with Brutus long enough, to where when he tells a story I always find it's worth listening too. As another old guy we don't always see eye-to-eye on everything, but I always listen and consider what he (and Brutus) have to say. I often learn something new that way or at least gain a different perspective on the issue. And even if I don't end up agreeing on the particular point under discussion, that new perspective can come in handy down the road in another context altogether.
(This post was edited by healyje on Jul 24, 2008, 6:39 PM)
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sungam
Jul 1, 2008, 11:20 AM
Post #39 of 39
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pipsqueekspire wrote: Silly climbers can't read- yet again....... Don't know who you are, and havn't read your other posts, but you piss me off already. Just thought I'd give you the heads up.
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