|
Post by gregggagliardi on Sept 5, 2013 9:25:54 GMT -8
Courtesy of Will Gadd on his recent post on the dangers of clipping the belay anchor as the first piece of protection I found this eye-opening 2005 IFMGA technical commission report on fixed point belays. I think this is well worth reading by rope leads who are belayed by basic students and other less experienced climbers. I also think consideration should be given to including this new information in Freedom 9. The existence of important information such as this within the guiding community only reinforces my belief that we need as much AMGA/IFMGA input into Freedom 9 as we can get. Here is the link www.outdoorlink.org/research-papers/part-5-belaying-lowres.pdf
|
|
|
Post by jasonmartin on Sept 6, 2013 14:42:28 GMT -8
Here's a great video on this subject: We've experimented with this a lot at AAI. It works well with bolts or ice screws but probably shouldn't be used with trad anchors unless they are completely and totally multi-directional. The biggest problem is the location of the belay point. If it's too high up, it's hard to bring in slack. Additionally, we found that using a GriGri to belay is difficult and puts more force on the climber when he takes a leader fall. When we belay off our bodies and somebody takes a leader fall, the movement of the body up, decreases the force on the climber. When we use other styles of belay, like a munter or a tube style device, there's a little rope slippage, so it doesn't hit the climber as hard. All that said, we did our experiments at a sport crag, with about twenty feet of rope out. So there wasn't that much stretch in the system. Jason
|
|
|
Post by jimnelson on Sept 7, 2013 16:32:03 GMT -8
Very interesting. A significant change from current/previous methods.
|
|
|
Post by gregggagliardi on Sept 9, 2013 8:25:26 GMT -8
How about a cordelette or equalette, tied or supplemented with a low leg on a really strong piece (or two) to resist an upward pull? How much force is felt at the belay anchor, and on the climber, assuming a FF 1.5 fall and 175lb climber using an autoblocking or tube style belay device? Using a GriGri or Cinch? In other words, how much force would the upward fall resisting leg need to hold to be safe?
|
|
|
Post by jasonmartin on Sept 9, 2013 9:08:25 GMT -8
Unfortunately, I don't know. We haven't experimented with it enough.
The AMGA is starting to teach this in the Ice Instructor Course. It still a pretty new technique for American Guides.
Thanks,
Jason
|
|
|
Post by gregggagliardi on Sept 9, 2013 11:54:54 GMT -8
I went back and re-read Mark Houston's paper (link in my first email). I found some data on upward pull forces. I am wondering if the tests conducted by Chris Semmel need to be replicated in a more systematic way (different ropes, different belay devices, greater range of FF, different kinds of pro and use of load limiting devices).
Semmel's estimate of the upward pull force (2- 2.5 Kn) suggests that a Screamer attached to the piece resisting the upward pull in the system might be a useful addition.
One possibility would be to attach an upward pull piece with screamer separately clipped directly to the belayer's belay loop, independent of the rest of the belay anchor. If effective this could work to accomplish the same thing as a fixed point belay with the more conventional belay off the harness when the belayer is tied into a cordelette/equalette anchor.
An additional advantage to fixed point anchoring against an upward pull is rescuing a fallen leader. It is a lot easier to tie off and escape the belay off of a fixed point than one that has violently shifted upwards 1 to 2 meters. This may not be much of an issue for guides since they don't expect to fall let alone have to be rescued by a client. However it might be important for recreational climbers who are often belayed by inexperienced belayers; i.e., first year intermediate rope leads who are commonly belayed by first year basic climbing students.
|
|
|
Post by gregggagliardi on Sept 19, 2013 10:16:50 GMT -8
Here is an interesting video on an application of the Alpine Up belay device (belaying a leader off an anchor in click up mode). The relevant section of the video (Fast forward to find it) shows a leader belayed off a common multi-point anchor set-up. It could be set-up on a fixed point anchor. Would setting it up one way (traditional) versus another (fixed point) make a difference in terms of the force on the top anchor? Either way there would be little or no force on lifting the belayer off his or her stance.
|
|