Rappelling with an ATC on a single rope

rgold wrote:

Test # 2 Our mass of 175 lbs. was attached to the SMC stainless steel rack that was rigged with 4 bars and raised to a height of 115 ft. After the release of the test mass the belayer was unable to stop or slow the mass and it impacted the ground.

Test # 6 Our mass of 150 lbs. was attached to the SMC stainless steel rack that was rigged with 4 bars and raised to a height of 200 ft. After the release of the test mass the belayer was unable to stop or slow the mass and it impacted the ground.

Since we are doing advanced copy and paste:

For all of the tests the 11 mm PMI pit rope (Max Wear) was anchored 700 ft above at the catwalk, came down to the ground and was revved through a change of direction pulley that ran horizontally to our belayer 50 ft away. 

It’s a real “stretch” to compare this to normal climbing. 

Greg D wrote: It’s a real “stretch” to compare this to normal climbing. 

And it would be an even bigger stretch to say the summary cautions do not apply to normal climbing.

Greg D wrote:

Since we are doing advanced copy and paste:

For all of the tests the 11 mm PMI pit rope (Max Wear) was anchored 700 ft above at the catwalk, came down to the ground and was revved through a change of direction pulley that ran horizontally to our belayer 50 ft away. 
It’s a real “stretch” to compare this to normal climbing. 

They used the setup to test drops from cimbing-relevant heights.  Certainly these tests aren't exactly like ordinary climbing situations.  I don't think the pulley redirection changes much but having all that rope above the start of the trial has some effect; not sure what it might be.  The fact that belayers were completely unable to control the descent ought to at least give ordinary climbers, many of who, as far as I can tell, have tested the situation just once with the rappeller a few feet away, just a little bit of pause eh?  In any case, I think I've suggested an effective work-around that doesn't take any more time and effort, but of course my only test was once with a rappeller at the very top of a ~150 foot rap.

Continue on but dang, talk about thread drift!    

Break bar racks look to have different applications than tubular belay devices.

Six bars appear to be sold  for rescue applications.  

The rope passing over a single bar looks to encounter far less friction than one passing through a tubular belay device hence the need for four or six bars.

Rgold, Pavel and Lawry make sold points on the limits of the fireman’s belay which have nothing to do with of one can actually arrest and falling rappeller with a fireman’s.   The fireman is far below and unable to smoothly control the descent and a belay from above has safety benefits in an alpine setting where the top belayer has more control. 

Taking those points as given, is the idea that one could not arrest a falling rappeller using an ATC with a fireman’s but could arrest a falling leader with the same device.  

Mu is reduced when surfaces are sliding.

There are fewer carabiners in a rappel than in a typical leader fall and as long as there is one piece in the leaders rope is bent Over a carabiner 180 degrees or close to it.  

Those factors make this position seem plausible. But it really comes down to the friction created by the tubular belay device.  

In particular, a hanging midway rappel station where a jump catch is difficult seems like a spot for extra caution. As well as an improvised belay device like a carabiner break bar probably requires extra care. 

No kidding!  I'm certainly done with the digession!

Mark Hudon wrote: Continue on but dang, talk about thread drift!    

.... busted by the OP.

Twisting Richard’s words a little here ... perhaps then it is criminal of the experienced to not almost always send the inexperienced first on one strand with independent belay from above.  Edit: strike “almost always”; replace with often.

The inexperienced can then mostly safely learn to deal with many of the challenges of going first in addition to learning to add friction before it is needed on a single strand ... perhaps the hard way.

Pre-requisites: competent at ascending; mechanically adept at avoiding injury by pendulum; enough daylight left; probably a few other things I am missing.

Hmmmm. All those always resorting to fireman’s with their beginners are doubly criminal. ;)

Well. Seems to this gumby the drift is headed rather charmingly close to the bigger picture in the original post: practice this shit, including a fireman's belay.

The end. :-)

How many inexperienced people die rappelling their first time a year?

How many of you "hurr durr 40 years experience" have friends or know people who've climbed for 20+ years and still rap off the end of their damn rope.......

rgold wrote:

They used the setup to test drops from cimbing-relevant heights.  Certainly these tests aren't exactly like ordinary climbing situations.  I don't think the pulley redirection changes much but having all that rope above the start of the trial has some effect; not sure what it might be.  The fact that belayers were completely unable to control the descent ought to at least give ordinary climbers, many of who, as far as I can tell, have tested the situation just once with the rappeller a few feet away, just a little bit of pause eh?  In any case, I think I've suggested an effective work-around that doesn't take any more time and effort, but of course my only test was once with a rappeller at the very top of a ~150 foot rap.

Well, with all due respect, despite all the copying and pasting from an article I already read, I am still not convinced these test are relevant for typical climber scenarios.  You are welcome to find them relevant.  

In the meantime, I will continue to do my own tests with real climbers, typical devices and scenarios, and (hold your breath) beginners.  I know, right.  Down right reckless.  I've been doing the fireman's for more than two decades with 100% success.  It is always tested at the start and I always demonstrate to my beginners how it works.  They cannot move until I release tension.  Of course, this should only be done on raps with good visual and voice contact for beginners.  But, that should be obvious.  All slack needs to be removed for it to be effective. That should be obvious, too.  As always, good judgement should be observed.  If a jump take is needed, I serious mistake was already made.  Have you really every needed this?