Bridge Day : Saturday

Discuss vertical caving, equipment, & techniques. Also visit the NSS Vertical Section.

Moderator: Tim White

Re: Bridge Day : Saturday

Postby Marduke » Oct 18, 2011 10:24 am

That's why our team uses long rope belay techniques, not short rope. Of course short rope bottom belay techniques don't work well for long ropes!!

Our belayers all wear a harness and QAS, and have an quick escape route which is downhill fast, so that if a rappeller goes out of control you can quickly get a full 300-400lbs of belay, which is MUCH more than you can achieve by simply pulling down on the rope.
Warning: Don't use this forum! Only armchair cavers and trolls reside here.
Marduke
NSS Hall Of Fame Poster
 
Posts: 373
Joined: Jul 8, 2008 8:16 am
Location: An alternate, non-sucky forum
  

Re: Bridge Day : Saturday

Postby Cody JW » Oct 18, 2011 11:44 am

Thanks for the post John. I figured someone had tested this at one time or another. . I see this test understood that it is not a good idea for the belay person to be right at the bottom of the rope, I sure would not want to be. It was not clear to me if the belayer was using a QAS, they mentioned the importance of grip.
Last edited by Cody JW on Oct 18, 2011 11:54 am, edited 1 time in total.
It only takes one person to surrender a dog to a kill shelter ,but it takes many to rescue it.
User avatar
Cody JW
NSS Hall Of Fame Poster
 
Posts: 905
Joined: Oct 24, 2007 10:16 am
Location: Indianapolis In. USA
Name: Jeff Cody
NSS #: 23961
  

Re: Bridge Day : Saturday

Postby DeanWiseman » Oct 18, 2011 11:53 am

I think part of the failure of weighted rope to work well for belay purposes is that weight applied in the direction of the rope's "fall line" is ultimately absorbed by stretch, and it's just hard to stretch rope to where it will stretch no more... and ever more so with long ropes.

So the big advantage with J-belay, or belay techniques where you're changing the angle of incidence of the rope,is that they force the rope to take a path that engages the rack/friction device more--either a more circuitous route or more surface contact with the bottom bar, or both. Secondly--and I think the wingsuit guy sort of makes this point--that any momentum which is shifted from the direction of gravity is momentum that can be dispersed more slowly and (hopefully) safely: You roll across the ground rather than crater into it.

-Dean
Image
User avatar
DeanWiseman
NSS Hall Of Fame Poster
 
Posts: 322
Joined: Jan 23, 2007 4:39 pm
Location: Indianapolis, Indiana
NSS #: 32690
Primary Grotto Affiliation: Central Indiana Grotto
  

Re: Bridge Day : Saturday

Postby Cody JW » Oct 18, 2011 11:58 am

DeanWiseman wrote:I think part of the failure of weighted rope to work well for belay purposes is that weight applied in the direction of the rope's "fall line" is ultimately absorbed by stretch, and it's just hard to stretch rope to where it will stretch no more... and ever more so with long ropes.

So the big advantage with J-belay, or belay techniques where you're changing the angle of incidence of the rope,is that they force the rope to take a path that engages the rack/friction device more--either a more circuitous route or more surface contact with the bottom bar, or both. Secondly--and I think the wingsuit guy sort of makes this point--that any momentum which is shifted from the direction of gravity is momentum that can be dispersed more slowly and (hopefully) safely: You roll across the ground rather than crater into

-Dean
It has been some time since I was there and I do not remember the exact nature of the ground below. How feasible is it for multiple teams to use a J- Belay at the bridge?? Is there enough elevation change to make this feasible ??
It only takes one person to surrender a dog to a kill shelter ,but it takes many to rescue it.
User avatar
Cody JW
NSS Hall Of Fame Poster
 
Posts: 905
Joined: Oct 24, 2007 10:16 am
Location: Indianapolis In. USA
Name: Jeff Cody
NSS #: 23961
  

Re: Bridge Day : Saturday

Postby Marduke » Oct 18, 2011 12:12 pm

Cody JW wrote: It has been some time since I was there and I do not remember the exact nature of the ground below. How feasible is it for multiple teams to use a J- Belay at the bridge?? Is there enough elevation change to make this feasible ??


Most of the rig points are on uneven ground where a J-Belay is feasible, except for those lines directly at the railroad tracks. Probably 2/3 of the landings are on a good slope.

I think the biggest problem for Bridge Day in particular is 3/4 of the belayers I see on the various teams don't know any belay technique other than "grab the rope and pull down with your bare hands", which is woefully inadequate.
Warning: Don't use this forum! Only armchair cavers and trolls reside here.
Marduke
NSS Hall Of Fame Poster
 
Posts: 373
Joined: Jul 8, 2008 8:16 am
Location: An alternate, non-sucky forum
  

Re: Bridge Day : Saturday

Postby self-deleted_user » Oct 18, 2011 12:21 pm

There is a lot of elevation change at the bottom of the bridge. It took me 10 min to climb up through the briars to rope 16! Now ok part of that was trying to get a path through the briars but it was basically an angle you'd climb a ladder at on a slick muddy slope trying (in vein) to not get puncture wounded haha. I should have taken a photo from my path I spotted to run down, about a 35deg downgrade for 10-15 feet and then after that a 10 ft dropoff to jump and more downhill after that. If you are on the railroad track area (flat) there is a lot of distance you can run and you can still get downhill to the shrubary between the tracks and the river itself. A lot of that whole side is really steep.

Of the teams I saw "belaying" we were the only ones not just hands-on-rope though. *shrugs* It is definitely feasible for everyone ground-wise if they so chose. Even if one of the few on-track spots, there is a lot of length to run to get angle change on the rope, and the next downhill section is not far at all, it drops right off again after the 15-20 ft width cleared and mostly flat where the tracks are.
Self-deleted due to large troll population on the forum, and absence of moderation.
self-deleted_user
NSS Hall Of Fame Poster
 
Posts: 1408
Joined: Aug 6, 2010 8:33 pm
Location: Offline, in real life, with real cavers.
  

Re: Bridge Day : Saturday

Postby Chads93GT » Oct 18, 2011 1:36 pm

I can't imagine most teams being able to run very far at all. The tree canopy is very dense, so I guess you could run them into the tree branches to break their fall if someone got out of control.
User avatar
Chads93GT
NSS Hall Of Fame Poster
 
Posts: 2293
Joined: Jun 24, 2008 1:27 pm
Location: Missouri
  

Re: Bridge Day : Saturday

Postby DeanWiseman » Oct 18, 2011 2:18 pm

Sungura wrote:Of the teams I saw "belaying" we were the only ones not just hands-on-rope though. *shrugs*



Well... OBVIOUSLY... you didn't see me. :big grin: I had that ascender on there at all times. I always like to wait until the guy following me squirmed before I'd redirect him off trees, but that's just my mean streak. :laughing:

Admittedly, I've not seen a true out-of-control rappel, but I can say that in many cases, I find that the further down the rope the rappeller is, the more effective the "re-direct J" (maybe not a true J) technique is. It's almost as if you're using the rappeller's weight as a form of mechanical advantage; Like a good running back, you have to wait for the play to set up before you pick your moment. No book would ever publish that... but it's something I've noticed.


-Dean
Image
User avatar
DeanWiseman
NSS Hall Of Fame Poster
 
Posts: 322
Joined: Jan 23, 2007 4:39 pm
Location: Indianapolis, Indiana
NSS #: 32690
Primary Grotto Affiliation: Central Indiana Grotto
  

Re: Bridge Day : Saturday

Postby self-deleted_user » Oct 18, 2011 2:44 pm

We were lucky with a tree-clear spot on 16 just needed a bit of guiding close to the ground to not land in the briars.

I have my photos up, rather than fuss with posting them here, just go here to my flickr set for them.

http://www.flickr.com/photos/sunguramy/ ... 800448419/
Self-deleted due to large troll population on the forum, and absence of moderation.
self-deleted_user
NSS Hall Of Fame Poster
 
Posts: 1408
Joined: Aug 6, 2010 8:33 pm
Location: Offline, in real life, with real cavers.
  

Re: Bridge Day : Saturday

Postby DeanWiseman » Oct 18, 2011 2:51 pm

Sungura wrote:We were lucky with a tree-clear spot on 16 just needed a bit of guiding close to the ground to not land in the briars.



Yeah... I think our team was 16 (maybe 18) my first year... it was cool because it was the one treeless spot almost anywhere down from the tracks back then.

Your photos look really good! I saw some of them on FB just a second ago. :kewl:

-Dean
Image
User avatar
DeanWiseman
NSS Hall Of Fame Poster
 
Posts: 322
Joined: Jan 23, 2007 4:39 pm
Location: Indianapolis, Indiana
NSS #: 32690
Primary Grotto Affiliation: Central Indiana Grotto
  

Re: Bridge Day : Saturday

Postby VACaver » Nov 2, 2011 11:02 am

It was my first as a participant and I only did two drops, but Bridge Day was GREAT!

What a beautiful day it was, too.

Looking forward to next year.
User avatar
VACaver
NSS Hall Of Fame Poster
 
Posts: 282
Joined: Sep 25, 2005 5:31 pm
Location: SW Virginia
Name: Patrick
  

Previous

Return to On Rope!

Who is online

Users browsing this forum: No registered users