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Rappel trick - Save a cam?


Blake

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I read of a trick to rappel from a cam, then get that cam back. Only works with U-stem models. Hitch a prusik to your rope next to the cam, and connect the prusik to the cam's trigger. Make sure there is copious amounts of slack. Pull your rope after you rappel, and you will pull the cam trigger, and your cam. Seems sketchy but theoretically possible. Anyone try it?

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Yes, this is right up there with the magic-ice-screw-retrieval-trick (prusik on rope, then coil around screw as it turns in, rap, then pull rope and spin screw out). I suppose if I had a multipitch route to descend and only a single screw or cam, I might consider it if no other options existed. Otherwise, as Ireneo said, "neat trick" and "rap" should never be in the same sentence.

Is your life worth $80?

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I wonder how fast a cam is going when it's fallen 60m?

 

distance fallen = 60m = A(t)(t)/2 where a = 9.8m/sec2, t = seconds falling.

 

solving, t = 3.5 seconds.

 

v = a(t) where v is velocity

 

ergo v = 34.3 m/sec or about 100 feet per second. Fast.

 

Geek_em8.gif

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I think I'd be less concerned about the cam and more concerned about the biner. The biner is stiff all around and is probably going to take hard impacts all the way down. The cam has lots of springy/bendy stuff. It'd have to impact in just the right orientation for it to take the same hard impact.

 

Guys in Yosemite make a business collecting pro at the bottom of cliffs and peddling it at Camp 4. I might buy a cam for cheap cheap, but I don't think I'd buy a biner.

Edited by Toast
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did someone actually pull this off, and have they ever heard of a v-thread

 

Taking an ice class, one instructor showed us this setup. The other instructor then (wisely) stepped in and called him an idiot for even thinking about it, let alone teaching it in a class.

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I read the same thing about getting t-slotted ice axes or pickets back via a prussick. Hmmmm..

option #1 (the more likely option)=it doesn't work and you gotta jug

option #2 = it does work and you have heavy sharp things falling towards you at 9.8 meters/second.

 

pretty sweet!

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Lowering off of one piece is also a bad idea.

 

I think I heard somewhere that lowering puts more force on the anchor than rappelling. Maybe one of the physics experts can elucidate it for us.

 

As memory serves you lowering increases the force on the anchor by a factor of 1.6 (when compared to a simple rap).

Rapping has 1/2 your bodyweight on each strand.

Lowering has your bodyweight on each of the strands (roughly).

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