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flyinglow
Jun 21, 2006, 8:29 PM
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Registered: Dec 11, 2005
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I am looking for information on the effects of climber weight on impact force.
I weigh around 210 lbs. Climbing mulitpitch, with a trad rack and some water, the weight falling on the rope could be as much as 240 lbs(~109kg). This is considerably more than the 80kg uiaa test.
Has anybody seen any relevant studies or hard numbers regarding forces on the anchor, particularly in high factor falls with heavy climbers?
I figure any climbing rope is likely to hold at least one factor 2 fall with my bodyweight, but i don't have any idea how many more it would take to fail the system. I know that ff2 falls are uncommon, and i'm not really planning on taking any, but it would be nice to know that the rope would actually stop me.
I currently own a mammut flash 10.5, and a beal booster 9.7 rope.
I'm not trying to be paranoid, just interested in applicable numbers for the worst case scenario in my situation.
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flyinglow
Jun 22, 2006, 5:03 AM
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Thanks, adatesman
the beal page has an equation to calculate impact force with a variable for climber weight.
Yikes my algebra is rusty...
If i've got it right the numbers i'm coming up with are somewhat reassuring though. On a rope with uiaa impact force of 9kn, adjusted for my bodyweight (worst case scenario) i'm still only getting an impact force around 10.67kn. (I used the table provided with the equation to calculate K)
I may go up to an 8mm cordelette though, as i've heard 7mm nylon is only rated for ~10kn(single strand) in some cases.
using my thinner rope as another example, the force was considerably lower, but i don't think it would take many falls, as i think it was only rated at 6-7 uiaa falls with 80kg. at 109kg, who knows...
I'd still like to get some hard numbers on the effects of weight on # of test falls held. If anybody has more infomation or comments to add they're welcomed.
--disclaimer: i'm not a mathematician, and it's been years since i took a math class, so my numbers may or may not be accurate at all.
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overlord
Jun 22, 2006, 7:02 AM
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"worse case scenario" is a factor 2 fall (meaning you fall twice the lenght of the rope before it starts to catch you) and you probably wont experience it ever. even factor 1 is pretty rare, and uiaa is factor 1.8 or something acroas a kinda thin rounded edge.
if youre worried, get a beffy rope, like 10.5 or 11mm and youll be fine.
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knudenoggin
Jun 28, 2006, 5:26 AM
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BINGO!!
I was about to respond with some quotes from (a paper copy of) that, which in
a slightly modified (?) form was presented by PMI at the Int.Tech.Rescue
Symposium in Nov.'99 (so it reads).
*knudeNoggin*
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majid_sabet
Jun 28, 2006, 6:46 AM
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I do not know what to say, I just spend few days in a classroom looking at things falling apart (rope/sling/anchor). they were using a 100 Kg weight and the result were some thing you do not wish to know.
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muslmutt
Jun 28, 2006, 11:30 AM
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I weigh 207 right now and have had similar concerns. Although my concerns differ in that they do not question the rope so much as that trad gear. Not always the gear per se, but also the rock around it as well.
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chadnsc
Jun 28, 2006, 12:56 PM
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You don't have anything to worry about. I weigh 230 pounds and have never had any problems with impact forces. Although a few of my belayers are not longer able to father children. . .
Actually those links regarding impact forces are quite interesting, thanks for posting them.
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flyinglow
Jun 28, 2006, 2:41 PM
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Registered: Dec 11, 2005
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In reply to: I do not know what to say, I just spend few days in a classroom looking at things falling apart (rope/sling/anchor). they were using a 100 Kg weight and the result were some thing you do not wish to know.
Actually I would like to know. I would rather know the kinds of situations to avoid than have them crop up unexpectedly.
Do you have any of the numbers(fall factor, weight, test circumstances, etc)
What kind of rope were you using?
How many falls were held before failure?
Were you able to record peak force at failure?
In reply to: if youre worried, get a beffy rope, like 10.5 or 11mm and youll be fine.
Actually, right now I'm leaning toward the thinner ropes, as they reduce the impact forces and consequently the chances of anchor failure. But I'm still looking for numbers of test falls held with heavier weights. If the thinner ropes will still hold a reasonable number of falls, then it should be *safer* to use a rope with lower impact force.
So far, we've gotten some really useful numbers on impact force, but no failure points (# falls held) for heavier weight.
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