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catbirdseat

"Reeling In" a Falling Leader

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Actually, Robmcdan is correct. The formula holds for both static and dynamic ropes. Which makes sense considering FF is not a measure of the force on the rope, but a *relative* indication of the force of falls of different lengths given the same rope and climber. In deriving the formula for the maximum force in a fall, the factors containing the rope stretch cancel out. Then you are left with factors containing a bunch of constant stuff -weight of the climber, properties of the rope - and the fall factor. The terms of the fall factor are the only things the leader has control of (by when/where he places gear) - all the other things are constant - which is why the FF is a useful measure.

 

Also, it has been stated several times in this thread that reeling increases the fall factor. This is not exactly correct. In fact, for fall factors < 1, reeling will decrease the FF. For fall factors = 0, reeling has no effect on the fall factor. For fall factors > 1, reeling will increase the fall factor (so Dru's post is correct, just incomplete). Go ahead, do the math.

 

fruit.gif : mathdance :

 

Also, note there is a difference between 'reeling' and back-pedaling (running downhill) wrt calculating FF. If you back-pedal, you are not shortening the total amount of rope absorbing the fall - to do this you actually need to pull rope through the ATC (as in 'reeling'). Of course, you still increase the force on the rope when you run, as you now have two masses falling downhill that the rope must bring to a stop.

 

rockband.gif

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Also, note there is a difference between 'reeling' and back-pedaling (running downhill) wrt calculating FF. If you back-pedal, you are not shortening the total amount of rope absorbing the fall - to do this you actually need to pull rope through the ATC (as in 'reeling'). Of course, you still increase the force on the rope when you run, as you now have two masses falling downhill that the rope must bring to a stop.

 

rockband.gif

By back pedalling, I am assuming you refer to the belayer. Sure it increases forces, but the idea is to prevent the leader from getting shredded on a slab fall. The forces aren't that great to begin with.

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Is anyone else getting mildly aroused by all this math talk?

 

Thanks Archenemy, I was worried I might be the only one. tongue.gif

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peas in a pod, I tell you, peas in a pod.

 

 

 

 

I have a little question too.

I've had a belayer tighten the rope up after I tell him I am in a sketchy spot (on TR of course). Anyone else admit to doing that? It is kind of like "pre-reeling" a falling loser, but it makes me feel better. Am I the only one on this?

 

(please show work in math proofs to get full credit for your answer)

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