Petzl Basic Modification

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

Moderator: Tim White

Postby hank moon » May 15, 2006 12:11 pm

hunter wrote:Hey Hank, Kind of delayed but thanks for the photo posts, that gives me a good idea of what was done.


You are welcome. :-)

hunter wrote:can anyone (Hank?) say for sure if that is an approved way to use the gri-gri?


Not approved. :shock:

hank
User avatar
hank moon
NSS Hall Of Fame Poster
 
Posts: 610
Joined: Sep 7, 2005 9:52 am
Location: Salt Lake City
  

Postby NZcaver » May 15, 2006 5:03 pm

hunter wrote:...Although the stop doesn't have quite the area for trapping debris it does seem possible that something similar could occur...

I was thinking of that little space formed between the flat surfaces on the top of the lower bollard, and the bottom of the upper one. The edge of that surface on the lower bollard is what crimps the rope against the upper bollard - and I was wondering if it could have the potential to trap a sharp rock. But it's true, your brake (non-handle) hand does naturally "clean" the rope as you descend.

I was just batting around a wild theory, that's all. :wink: Sorry for veering off-topic... :oops:
Last edited by NZcaver on May 15, 2006 5:23 pm, edited 1 time in total.
User avatar
NZcaver
Global Moderator
 
Posts: 6367
Joined: Sep 7, 2005 2:05 am
Location: Anchorage, Alaska
Name: Jansen
NSS #: 50665RL
  

Postby potholer » May 15, 2006 5:23 pm

The channel between the cam is basically straight - debris getting on the lower edge of the channel (the upper edge of the lower cam) would seem likely to go right through and then be pulled round the curving lower cam face.
Possibly there's a slightly greater chance of something getting caught in the vague wedge-shaped are round the reinforcing pin on the upper cam, but would have to have been dragged round the top cam first.
Still it'd be worth bearing in mind for odd belay operation where there was debris around.

I wonder, would caving rope with its generally tighter weave and relatively thicker sheath be any more resistant to debris-damage - would anything sharp be more likely to get embedded in the rope and pulled through a device?
potholer
NSS Hall Of Fame Poster
 
Posts: 381
Joined: Nov 9, 2005 7:29 am
Location: UK
  

Postby hunter » May 15, 2006 5:47 pm

NZCaver, makes sense to me although it seems like a long shot from there to cutting the rope. Of course I would have said the same thing for a gri-gri. I am still really amazed by that report!
On a more mundane note this could provide a reasonable argument for higher rope wear with a stop than a rack....

Hunter
hunter
NSS Hall Of Fame Poster
 
Posts: 395
Joined: Sep 9, 2005 9:47 am
Location: New Mexico
  

Postby NZcaver » May 15, 2006 6:54 pm

hunter wrote:On a more mundane note this could provide a reasonable argument for higher rope wear with a stop than a rack....

But are we talking aluminum or stainless bars...? :tonguecheek:
User avatar
NZcaver
Global Moderator
 
Posts: 6367
Joined: Sep 7, 2005 2:05 am
Location: Anchorage, Alaska
Name: Jansen
NSS #: 50665RL
  

Postby Scott McCrea » May 17, 2006 2:39 pm

I added better pictures to my post. It's the first post in this thread.
Scott McCrea
SWAYGO
User avatar
Scott McCrea
Global Moderator
 
Posts: 3198
Joined: Sep 5, 2005 3:07 pm
Location: Asheville, NC USA
NSS #: 40839RL
Primary Grotto Affiliation: Flittermouse Grotto
  

Postby Dwight Livingston » Jul 11, 2006 6:22 pm

(. . . moved to this thread)

This past Sunday morning, climbing out of the entance pit of Hellhole, I found my Croll had misbehaved, just as described in the previous posts. I had stopped in the upper section of the pit, standing on a ledge and leaning forward against the wall. After a short breather, I raised my foot loops, stood, and tried to sit. The croll didn't grab, so I shifted my weight, trying to help it catch. When that didn't work, I looked down and saw the Croll latched open. My first thought was "Hey, that does really happen." So I closed it and continued out.

I wasn't aware of it happening, but I expect that I dragged the croll against the wall, and that action latched it open. Good thing to avoid.
User avatar
Dwight Livingston
NSS Hall Of Fame Poster
 
Posts: 323
Joined: Sep 6, 2005 7:17 am
NSS #: 27411
Primary Grotto Affiliation: Baltimore Grotto
  

Postby NZcaver » Jul 11, 2006 6:36 pm

(...also moved over to this thread from http://www.caves.org/phpBB2/viewtopic.p ... 4&start=39 ...)

Dwight wrote:...I looked down and saw the Croll latched open. My first thought was "Hey, that does really happen." So I closed it and continued out.

I wasn't aware of it happening, but I expect that I dragged the croll against the wall, and that action latched it open. Good thing to avoid.

Dwight - thanks for sharing this! :-) If you don't mind, I have a few questions about the incident.

In your opinion as a vertical caver, how much do you think the safety catch on your Croll contributed to this happening - versus your technique? I don't mean to imply you did anything wrong, just that sliding up the rock - accidentally of course - with any cammed ascender could cause problems. Do you now feel this safety catch design is entirely at fault, making your Croll a useless liability? Or do you feel this is a 50/50 design/technique issue, or perhaps you have a different analysis?

You comments about this seem very calm. Did you feel the same way when it actually happened? I'm interested to compare your thoughts with previous comments on a similar incident, mentioned earlier in this thread. In that situation, the unexpected disconnecting of one ascender (leaving only one other gripping the rope) was emotionally described as being "life threatening". Did you feel the same way when it happened to you?

Thanks! :grin:
User avatar
NZcaver
Global Moderator
 
Posts: 6367
Joined: Sep 7, 2005 2:05 am
Location: Anchorage, Alaska
Name: Jansen
NSS #: 50665RL
  

Postby fuzzy-hair-man » Jul 12, 2006 1:18 am

The catch on my Croll coming undone doesn't really keep me up at night.

I generally try to turn 90 degrees to the wall so my side (generally left hand side is against the rock) and this pushes the rope away from the wall and makes it easier to progress. Granted it is not always possible, otherwise I tend to use my toes and or knees to push away from the wall. Once I have stood up the croll might be against the wall but it is not moving by then. This means my croll is not sliding up beside the rock. I can also drop one foot out of the foot loop to help fend off the wall.

I'm sort of thinking the Croll releasing is likely a problem for rope-walkers and not froggers :question: Froggers will tend to bring thier knees up more and as a result push away from the wall, by the time the Croll is close to the wall again the upwards movement has just about run out.... :kewl:
User avatar
fuzzy-hair-man
NSS Hall Of Fame Poster
 
Posts: 955
Joined: Apr 6, 2006 2:09 am
Location: Canberra, Australia
Primary Grotto Affiliation: NUCC
  

Postby potholer » Jul 12, 2006 3:42 am

I'm sort of thinking the Croll releasing is likely a problem for rope-walkers and not froggers...


I think that's pretty much it - when frogging, the body usually ends up at least slightly 'crouched', and even when against a wall and with the body most straightened-out, it's hard to see how a Croll could get closer than a few inches away from the wall.
Possibly frogging in a *very* tight pitch there's a chance of disengagement due to rock, but I don't recall experiencing that.

The only times I have had a Croll disconnection has been in a hybrid frog-ropewalking rig, basically the addition of a fixed foot-jammer to a regular frog rig, and I'm not *sure* I've had that happen to any design other than a very old one.
Even then, the key to the disconnection was having something (in my case, the footloop knot at the hand-jammer) slightly fouling the Croll safety catch at the point when the Croll was about to move upwards - anything catching once the Croll was significantly moving wouldn't have been a problem, since the catch would then have been 'locked' against the frame by the cam.
The precise same problem wouldn't be nearly as likely with a frog system, since the knot would only likely approach the Croll when the Croll was moving upwards normally, fully cam-down, and not susceptible to accidental opening.
potholer
NSS Hall Of Fame Poster
 
Posts: 381
Joined: Nov 9, 2005 7:29 am
Location: UK
  

Postby Dwight Livingston » Jul 12, 2006 9:05 am

NZcaver wrote:In your opinion as a vertical caver, how much do you think the safety catch on your Croll contributed to this happening - versus your technique? I don't mean to imply you did anything wrong, just that sliding up the rock - accidentally of course - with any cammed ascender could cause problems. Do you now feel this safety catch design is entirely at fault, making your Croll a useless liability? Or do you feel this is a 50/50 design/technique issue, or perhaps you have a different analysis?


I expect I can avoid doing it again, though it'd be nice if the Croll latch design made it less likely to happen. I'll be more aware of it now, particularly when I have one foot out of my footloop. If I'd had both feet it my single footloop, I don't see how I'd be able to slide my chest against the wall.

I expect you could design or modify some of this problem out of the Croll.

NZcaver wrote:You comments about this seem very calm. Did you feel the same way when it actually happened? I'm interested to compare your thoughts with previous comments on a similar incident, mentioned earlier in this thread. In that situation, the unexpected disconnecting of one ascender (leaving only one other gripping the rope) was emotionally described as being "life threatening". Did you feel the same way when it happened to you?


I'm timid about being on rope, but somehow incidents like this don't change my state of mind much while it's happening. Once in Stevens Gap I started down on four bars, tried to add a bar, and found myself on three instead. Same kind of reaction - think "Okay, this is how you kill yourself," then fix it, continue down.
User avatar
Dwight Livingston
NSS Hall Of Fame Poster
 
Posts: 323
Joined: Sep 6, 2005 7:17 am
NSS #: 27411
Primary Grotto Affiliation: Baltimore Grotto
  

Postby Dwight Livingston » Jul 12, 2006 9:19 am

fuzzy-hair-man wrote:I'm sort of thinking the Croll releasing is likely a problem for rope-walkers and not froggers :question: Froggers will tend to bring thier knees up more and as a result push away from the wall, by the time the Croll is close to the wall again the upwards movement has just about run out.... :kewl:


I agree when the pitch is vertical, but I think where there is some slope froggers must take care their Croll does not contact the wall.
User avatar
Dwight Livingston
NSS Hall Of Fame Poster
 
Posts: 323
Joined: Sep 6, 2005 7:17 am
NSS #: 27411
Primary Grotto Affiliation: Baltimore Grotto
  

Postby Tubo Longo » Jul 12, 2006 2:18 pm

Dwight, I assume you're a frogger, right? What puzzle me, in incident like your, is the fact that the cam, to be fully opened, needs not only to be pulled downward but side way too. I have been able to reproduce this kind of opening on the carpet at home, but I see it a bit more difficult on rope, unless someone - as potholer pointed out - is in a very tight pit, sort of a vertical crawl indeed. Which is not what you reported. It might be that some other piece of gear might have interacted with the cam while you resumed climbing for the ledge? And if so, what? :question:

Also, I don't see the problem of having a foot out of the foot loop: it should indeed help you staying away (i.e. rubbing) from the rock and have a better overall balance, isn't it? I means, to me is the only valid point to climb with a single foot: I use the other to stay clear of the wall and have a better overall climbing, instead than rubbing myself on the wall and having a miserable climbing tech. (while may be even dislodging some rocks to be sent as gracious gift to my buddies waiting below..)
Tubo Longo
Prolific Poster
 
Posts: 196
Joined: Apr 25, 2006 3:09 pm
Location: near Tacoma, WA
Name: Renato
NSS #: ex 29271
Primary Grotto Affiliation: CGEB SAG CAI of Trieste [Italy]
  

Postby Dwight Livingston » Jul 12, 2006 9:13 pm

Tubo Longo wrote:Dwight, I assume you're a frogger, right? . . . It might be that some other piece of gear might have interacted with the cam while you resumed climbing for the ledge? And if so, what? :question:


Frog, yes, without Pantene. I don't believe other equipment was involved, nor would it be necessary. And not a tight pit at all, but a place with a slight slope, allowing me to lean against the wall slightly, just for a moment. An avoidable act, if you take care to.

Tubo Longo wrote:Also, I don't see the problem of having a foot out of the foot loop:


It is not necessarily a problem, but it does allow one to raise up without sticking one's knees straight ahead. I think if you play around with it, you'll find it easier to drag your chest against the wall when you have a foot out. Not that you'd want to. I am suggesting that it is a time to take more care to avoid dragging the Croll along the wall.
User avatar
Dwight Livingston
NSS Hall Of Fame Poster
 
Posts: 323
Joined: Sep 6, 2005 7:17 am
NSS #: 27411
Primary Grotto Affiliation: Baltimore Grotto
  

Petzl ascenders coming off rope

Postby caverd » Jul 20, 2006 6:07 pm

The Petzl ascenders coming off rope issue does not have to be linked to draging the ascender against any rigid surface such as rock. As I've posted previously in one of these threads about this subject, I personally saw a climber have two of the newer Petzl ascenders come off rope THREE times each within 5 minutes. I was climbing right below him the entire time. We were not even close to any rock when this happened. His system is a rope walker. I saw nothing that made me believe there was any outside influence on the ascenders (could I have missed something....sure).

Has anyone experienced this with the older designs of the Petzl Croll and/or Basic? None of my caving group using the older designs has ever experienced this type of failure.
User avatar
caverd
Occasional Poster
 
Posts: 46
Joined: Sep 19, 2005 7:00 am
Location: Evansville, IN
  

PreviousNext

Return to On Rope!

Who is online

Users browsing this forum: No registered users

cron