Deleted Megajul Thread

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Messages 1 - 7 of total 7 in this topic
rgold

Trad climber
Poughkeepsie, NY
Topic Author's Original Post - Jul 29, 2014 - 07:43pm PT
The OP (don't recall name) deleted all his posts. What remains if anyone is interested is here: http://www.supertopo.com/climbing/thread.php?topic_id=2457383&msg=2457398#msg2457398

Of course, you can't reply to it any more unless you put your post in this thread.
klk

Trad climber
cali
Jul 29, 2014 - 09:19pm PT
yeah, that's bogus. i normally don't care if a thread gets deleted. but this is truly lame.

rich, you said:

I've held one real factor-2 fall on a climb and a whole bunch of factor 1.8 falls with weights with a hip belay, so I know for sure it works even in these very extreme situations.

i might be able to say the same, but that was years ago with 11mm ropes that had none of the kind of processing and coating that we have now. i'm less optimistic about hip belays with the new teflon floss-- so i would add that caveat (unless one of those falls you caught by hand was on a mammut revelation or similar.)

sorry the thread is gone-- jim's stuff is usually good
rgold

Trad climber
Poughkeepsie, NY
Topic Author's Reply - Jul 29, 2014 - 09:29pm PT
Yes, you're right, I don't know either if a hip belay would work so well with a thin slippery rope.

I've held a factor~1.8 or so fall with a Reverso 3 (I think; not the 4) on a single 8.5mm strand of a pair of Mammut Genesis half ropes, so the gadgets can work too. I was wearing gloves (almost always do) and there was a very small amount of rope slippage (perhaps a foot) that would have given me burns had I been bare-handed.
blahblah

Gym climber
Boulder
Jul 29, 2014 - 09:50pm PT
rgold, thanks for your comment in the deleted thread about the Revero manual instructing to belay through the anchor on multipitch (if I understand it correctly), and for acknowledging that the ATC manual doesn't seem to have such a warning. I suppose it's caveat emptor for using belay devices for multipitch belaying.

Just so it doesn't seem like I'm always contradicting you, I fully support your safety message for belayers to wear gloves, I almost always wear them and plead with my partners to do so, but get about as much traction as I do with most of my other comments here.

It is strange that people who read about climber after climber gettting dropped by a belayer who is burning his/her hands still don't wear gloves, but I guess to most people, belay accidents are the type of thing that only happens to the other guy.
Dingus McGee

Social climber
Laramie
Jul 30, 2014 - 05:45am PT
Rgold,

the graphs you show of these devices in the deleted post illustrate how incorrectly our intuition can be about how these devices perform under higher loading i.e. the right hand side of the graph. The Megajul clearly has a very flat curve meaning disproportional higher resistance is needed to hold a modest load increase.

Once I was in a body recovery mission and was the person managing the restraining rope for six people carrying the body bag/frame down a steep talus field. For the friction device I chose what was the first of these ATC like devices that had teeth like grooves and was then the "best" on the current market.

Soon into the lowering I begin to see that the device under these modest to high loads did not perform anywhere near the linear performance I had assumed it would give. Lowering them took all the restraining force I could muster and they had not got to the steepest portion of the descent. Fortunately, I had anchored to a large tree and could wrap the rope around the tree. I knew wrapping the rope around the tree would give exponential decay per wrap in the needed resistance. Soon I had the load under easy control.
mike m

Trad climber
black hills
Jul 30, 2014 - 08:49am PT
Keep it simple and hold on when needed always seemed like a good idea. That is why I think Trad climbing is obviously the best style because you are not constantly having to hold on to the rope with someone hanging on it. You are obviously scared that you may die so you do not hang or fall. In fact four points of contact is recommended.
rgold

Trad climber
Poughkeepsie, NY
Topic Author's Reply - Jul 30, 2014 - 09:08am PT
the graphs you show of these devices in the deleted post illustrate how incorrectly our intuition can be about how these devices perform under higher loading i.e. the right hand side of the graph. The Megajul clearly has a very flat curve meaning disproportional higher resistance is needed to hold a modest load increase.

Quoted for emphasis! It is natural to think a device that locks under low loads will provide more assistance than conventional plates in handling very high loads, but Jim's tests suggest otherwise, dramatically otherwise in some cases.

Many people have already and will continue to argue that the high-load scenarios are extremely rare and the locking behavior for most normal situations is well worth the trade-off. As in many things in climbing, the decision involves balancing various risks and probabilities and there is no one-size-fits-all answer.

The one thing I would suggest is that it is even more important than usual to use gloves with an assisted locking device in multipitch climbing, because in a high-impact situation it appears that it will provide less help than an ATC-XP and so the likelihood of the rope running through the device and your hands is greater than with conventional plates.

An interesting and so far unexplored corollary is that the assisted locking devices, which are suspected of creating higher anchor loads than conventional plates, may not do that for big impacts because they actually slip more!
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