Rappel trick - Save a cam?

[Dru]

Lower off a nut and leave it for the

[forrest_m]

the 1.6 is an average based on the friction between various parts of the system in a "typical" setup. YMMV - overhanging sport climb, probably pretty close to the "ideal" of 2. lowering from the top of mountaineers dome with the rope running across 50' of low angle slab? anchor would be lucky to feel even 1 (i.e. bodyweight of the climber)

[dylan_taylor]

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).

 

Lowering creates a pulley effect on the anchor only if it is redirected. Lowering a person from a device on a belay anchor and rapelling off the anchor put the exact same force on the anchor, provided no one bounces around. Lowering off of a sketchy anchor is actually a decent technique as long as that anchor is backed up by another. Then it can be removed once it passes the guinea pig test.

[crazyjizzy]

Lowering creates a pulley effect on the anchor only if it is redirected. Lowering a person from a device on a belay anchor and rapelling off the anchor put the exact same force on the anchor, provided no one bounces around. Lowering off of a sketchy anchor is actually a decent technique as long as that anchor is backed up by another. Then it can be removed once it passes the guinea pig test.

 

"Most" lowering scenerios do involve a re-direction of the rope. I guess that you could argue that lowering directly from the device loads the anchor the same as a rapell. But how about the lowerer? And I have found that lowering in said manner often results in a jerky ride. I think the arguement is getting parsed way too much here.

[Jason_Martin]

I tried this trick about three years ago after completing a first ascent in Red Rock Canyon. I was climbing with a beginner level climber at the time.

 

During the descent we came to a spot where there really was no way to rappel without leaving a cam. There was a ten foot overhung drop. It was impossible to downclimb. I subsequently lowered my partner off of a complete anchor and then rigged a single TCU with the rope and a prusik cord. The rappel went smoothly and I was able to retrieve the cam.

 

I don't think that I'd be psyched to use this technique in any other circumstances. The whole situation concerned me from beginning to end. If the cam didn't pull correctly, I would have to reascend the rope to retrieve it. This "double jeporady" element of the technique scared me.

 

At the time I decided that the potential fall was short and that the consequences would be low enough for me to risk it. I would most likely still get hurt, but at the time I felt that it was worth the risk. Now three years later I still haven't reused the trick...this is a testament to how sketchy I thought it was when I did it.

 

Jason