|
majid_sabet
Jul 3, 2009, 7:06 AM
Post #1 of 26
(7238 views)
Shortcut
Registered: Dec 13, 2002
Posts: 8390
|
IMO, the Purcell prussic is among the top safest climbing software to attach in case of falling on an anchor .
what you think ?
|
|
|
|
|
nikmit
Jul 3, 2009, 8:59 AM
Post #2 of 26
(7202 views)
Shortcut
Registered: Feb 10, 2009
Posts: 55
|
Prussic- climbing SOFTWARE?!? WTF ?!? 
The best way to attach to anchor IMHO is to attach with the climbing rope:
Pros: 1. It’s dynamic- it CAN take falls with 1+ factor(I’ve seen that nonsense) and in case of fall it softens the load on the anchor.
2. Reduces the bulk on the harness.
Cons: None that I can think of.
|
|
|
|
|
swaghole
Jul 3, 2009, 11:15 AM
Post #3 of 26
(7186 views)
Shortcut
Registered: Sep 20, 2006
Posts: 371
|
nikmit wrote: Prussic- climbing SOFTWARE?!? WTF ?!? The best way to attach to anchor IMHO is to attach with the climbing rope: Pros: 1. It’s dynamic- it CAN take falls with 1+ factor(I’ve seen that nonsense) and in case of fall it softens the load on the anchor. 2. Reduces the bulk on the harness. Cons: None that I can think of.
Using the climbing rope isn't always the best way to tie in to the anchor in all situations but it should definitely be part of a climber's bag of tricks. Having a personal anchor you can clip quickly (sling, daisy chain, purcell, 8mm cord, etc...) is a good way to stay safe, speed things up and make your rappels safer.
Personally, I hate the daisy chain...
|
|
|
|
|
socalclimber
Jul 3, 2009, 11:34 AM
Post #4 of 26
(7181 views)
Shortcut
Registered: Nov 27, 2001
Posts: 2437
|
Frankly I don't think either is the "best" or "safest" way. I prefer to use a clove hitch backed up with a figure 8. Simple, clean, quick to rig, and easy to adjust.
I really dislike cluster fuckage at the belay, and all tha extra crap isn't necessary.
|
|
|
|
|
nikmit
Jul 3, 2009, 12:06 PM
Post #5 of 26
(7167 views)
Shortcut
Registered: Feb 10, 2009
Posts: 55
|
In reply to: Using the climbing rope isn't always the best way to tie in to the anchor in all situations but it should definitely be part of a climber's bag of tricks. Having a personal anchor you can clip quickly (sling, daisy chain, purcell, 8mm cord, etc...) is a good way to stay safe, speed things up and make your rappels safer..
True, but in those situations when you need to use a sling you can always grab one out of the rack, add a locker attach it to your harness and you're good to go. For me there is no need the sling/daisy to be always on my harness.
|
|
|
|
|
Aunor
Jul 3, 2009, 12:33 PM
Post #6 of 26
(7148 views)
Shortcut
Registered: Jun 18, 2008
Posts: 39
|
Attach in with the rope, still when I am climbing with someone less experienced I put a PAS on them. Hard to screw that up.
Having said that, majid_sabet is asking if a Purcell prussic is among the top safest in cases of falling on an anchor.
I would have to say attach in with the rope is the safest in cases of falling on an anchor.... debating over 2rd, 3rd and 4th place, when second place is a distant second? Not much value in that.
|
|
|
|
|
acorneau
Jul 3, 2009, 1:17 PM
Post #7 of 26
(7127 views)
Shortcut
Registered: Feb 6, 2008
Posts: 2889
|
I'm pretty sure we went through this discussion just a few months ago, but...
I have been using a Purcell prussic for a couple of years now. As far as non-rope tethers they are a superior system over daisy chains and PAS-style tethers.
For multi-pitch climbs I usually tether in temporarily with the Purcell, then put together the anchor and clove in with the rope.
|
|
|
|
|
moose_droppings
Jul 3, 2009, 3:13 PM
Post #8 of 26
(7085 views)
Shortcut
Registered: Jun 7, 2005
Posts: 3371
|
Yep, I'll tether to the anchor most of the time with my purcell prusik, sometimes I'll use the rope, depends.
|
|
|
|
|
Tipton
Jul 3, 2009, 4:36 PM
Post #9 of 26
(7048 views)
Shortcut
Registered: Jul 12, 2007
Posts: 272
|
Purcell's are also great for rap anchors. It's nice being able to adjust my stance while I wait on my partner to get to rap and pull the rope.
|
|
|
|
|
binrat
Jul 3, 2009, 5:04 PM
Post #10 of 26
(7032 views)
Shortcut
Registered: Jul 27, 2006
Posts: 1155
|
Hmm,
Purcell prussic vs a aid climbing gear......
Purcell, I've been using off / on for 10 years now.
binrat
|
|
|
|
|
ski.ninja
Jul 3, 2009, 6:52 PM
Post #11 of 26
(6996 views)
Shortcut
Registered: Oct 8, 2008
Posts: 123
|
How about something like this? http://www.mec.ca/...;bmUID=1246646668714 The Beal Dynaconnexion. It's a sewn dynamic sling with multiple clip in points for snug belay stations and/or rap extension, plus it's been drop tested.
# Extremely strong 2200kg breaking load.
# Factor 1 falls impact force: 6.2 kN.
# Factor 1 falls rating: 20.
# Factor 2 falls impact force: 9.5 kN.
# Factor 2 falls rating: 15.
# Length is 80cm.
(This post was edited by ski.ninja on Jul 4, 2009, 8:32 AM)
|
|
|
|
|
jsj7051
Jul 3, 2009, 8:17 PM
Post #12 of 26
(6967 views)
Shortcut
Registered: May 31, 2007
Posts: 114
|
Not sure what a Purcell Prussic is , and the Beal product looks interesting . I have a multi-loop PAS and I use it or the rope , depending on the situation. I would not use a Daisy . The Pas makes it fast and easy for multi-pitch rapps.
Can someone explain a Purcell. Thanks
ski.ninja wrote: How about something like this? The Beal Dynaconnexion. It's a sewn dynamic sling with multiple clip in points for snug belay stations and/or rap extension, plus it's been drop tested. [image]http://www.bealplanet.com/portail-2006/img/produits/DYNA_CONNEXION_PUB.jpg[/image] |
|
|
|
|
Tipton
Jul 3, 2009, 9:29 PM
Post #13 of 26
(6941 views)
Shortcut
Registered: Jul 12, 2007
Posts: 272
|
The Beal thingy looks about as useful as a regular sling to me. I can throw overhands in a regular sling to accomplish the same level of adjustment that the Beal thingy has. The only added benefit is that it is more dynamic. As far as I can tell, the Beal thingy has no advantage over tying in with the rope, plus the disadvantage of not being easy to clove.
Also, Purcells have been tested, the results are in this thread somewhere:http://www.canyoneering.net/...php?t=700&page=6.
I'm not advocating tying in with the purcell instead of the rope, but it is definitely a useful tool if you're going to be carrying prussic cords anyway.
|
|
|
|
|
majid_sabet
Jul 3, 2009, 11:22 PM
Post #14 of 26
(6922 views)
Shortcut
Registered: Dec 13, 2002
Posts: 8390
|
ski.ninja wrote: How about something like this? The Beal Dynaconnexion. It's a sewn dynamic sling with multiple clip in points for snug belay stations and/or rap extension, plus it's been drop tested. [image]http://www.bealplanet.com/portail-2006/img/produits/DYNA_CONNEXION_PUB.jpg[/image]
is that thing adjustable like Purcell ?
|
|
|
|
|
hafilax
Jul 3, 2009, 11:40 PM
Post #15 of 26
(6917 views)
Shortcut
Registered: Dec 12, 2007
Posts: 3025
|
majid_sabet wrote: ski.ninja wrote: How about something like this? The Beal Dynaconnexion. It's a sewn dynamic sling with multiple clip in points for snug belay stations and/or rap extension, plus it's been drop tested. [image]http://www.bealplanet.com/portail-2006/img/produits/DYNA_CONNEXION_PUB.jpg[/image] is that thing adjustable like Purcell ? 
|
|
|
|
|
I_do
Jul 4, 2009, 3:23 AM
Post #16 of 26
(6889 views)
Shortcut
Registered: Mar 2, 2008
Posts: 1232
|
majid_sabet wrote: IMO, the Purcell prussic is among the top safest climbing software to attach in case of falling on an anchor . what you think ?
I think you shouldn't fall on an anchor and shouldn't advocate the use of daisies as personal safety's on the internet is what i think. Other then that, use the rope if you might fall on the anchor.
|
|
|
|
|
rgold
Jul 4, 2009, 3:25 AM
Post #17 of 26
(6889 views)
Shortcut
Registered: Dec 3, 2002
Posts: 1804
|
A lot of these discussions seem to me to confuse materials, construction, and function.
It seems from such tests as we have that anything made of high-strength, low elongation material will break under a factor-two fall and will generally develop unacceptably high tensions even at lower fall factors.
I don't think there is much reason to believe that a purcell prussik tether made of such materials will be any safer than any of the other systems. Purcell prussik "superiority" is a function of the fact that it is typically tied with dynamic cord, that's all. Perhaps the knot will slip under load and absorb some energy too, but I'm not aware of any test that indicates such slippage occurs or suggests that it is effective in absorbing energy.
So there is nothing in the design of a purcell prussik that make it preferable. And there are definite drawbacks in terms of convenience: a purcell prussik has a significantly smaller range of adjustment than a daisy---essentially you have a range from full-length to half length, nothing shorter. Adjustment in some circumstances can be extremely difficult---for example, you can't shorten a purcell prussik with one hand unless it is clipped in and partially tensioned.
The real comparison ought to be between a purcell prussik and the Sterling Chain Reactor, which is also made of dynamic material and won't break under a factor-2 fall. In this comparison, I think the Chain Reactor wins because of the quickness and ease of one-handed adjustment in both directions under all conditions and because of the additional range available.
The one advantage of a purcell prussik is that you can untie it and use it as rappel material. That's what I did with mine, and I never went back.
|
|
|
|
|
bill413
Jul 4, 2009, 4:01 AM
Post #18 of 26
(6879 views)
Shortcut
Registered: Oct 19, 2004
Posts: 5674
|
rgold wrote: A lot of these discussions seem to me to confuse materials, construction, and function.
I think this applies to a great number of discussions about climbing equipemnt & techniques (not only here on RC.com).
In reply to: It seems from such tests as we have that anything made of high-strength, low elongation material will break under a factor-two fall and will generally develop unacceptably high tensions even at lower fall factors.
Not surprising, but apparently too frequently forgotten.
As usual, superb writing on all points.
|
|
|
|
|
ski.ninja
Jul 4, 2009, 8:41 AM
Post #19 of 26
(6848 views)
Shortcut
Registered: Oct 8, 2008
Posts: 123
|
Did you get one? I've seen them hanging on the rack at the Broadway MEC and it's on my wish list. Used to use a couple of daisys for work, they're all retired now. I'll probably send two along to Aric for testing. One was an Onsight and the other a BD. For the record, I worked through 1 1/2 rows of bartack in three months on one pocket of the BD just with bodyweight.
|
|
|
|
|
acorneau
Jul 4, 2009, 2:23 PM
Post #20 of 26
(6817 views)
Shortcut
Registered: Feb 6, 2008
Posts: 2889
|
rgold wrote: Purcell prussik "superiority" is a function of the fact that it is typically tied with dynamic cord, that's all. Perhaps the knot will slip under load and absorb some energy too, but I'm not aware of any test that indicates such slippage occurs or suggests that it is effective in absorbing energy.
I'm not sure if you're considering normal accessory cord as "dynamic", but most folks I know would consider it more static.
According to this study...
http://www.caves.org/...yardsPartII-2006.pdf
... all of the 64 sampled Purcell prussic hitches slipped ~20 to 30 centimeters to dissipate the energy.
In reply to: In this comparison, I think the Chain Reactor wins because of the quickness and ease of one-handed adjustment in both directions under all conditions and because of the additional range available.
However, you can't adjust a CR without either unlocking and opening up the biner or using a second biner. A Pucell can be adjusted without having to open the carabiner.
|
|
|
|
|
vegastradguy
Jul 4, 2009, 3:22 PM
Post #21 of 26
(6805 views)
Shortcut
Registered: Aug 28, 2002
Posts: 5919
|
acorneau wrote: I'm not sure if you're considering normal accessory cord as "dynamic", but most folks I know would consider it more static.
normal accessory cord is considered more dynamic than static in this situation because it is made of nylon and there for stretches somewhat, despite being considered closer to static cord (static rope, btw, does stretch, just not enough to be safe).
in this discussion, 'static' material is dyneema, which doesnt stretch at all when loaded, unlike nylon which does (like the chain reactor v the PAS). anything made of nylon is somewhat dynamic, as opposed to dyneema which really isnt.
In reply to: However, you can't adjust a CR without either unlocking and opening up the biner or using a second biner. A Pucell can be adjusted without having to open the carabiner.
sortof. you can always clip another loop with a separate carabiner before unclipping the loop @ anchor (which i'll do occasionally, depending on whats going on).
(This post was edited by vegastradguy on Jul 4, 2009, 4:38 PM)
|
|
|
|
|
rgold
Jul 4, 2009, 4:10 PM
Post #22 of 26
(6795 views)
Shortcut
Registered: Dec 3, 2002
Posts: 1804
|
There are no comments in the write-up claiming that slippage results in energy absorbtion. The data is not particularly conclusive: in the factor-2 falls, longer slippage does correspond to lower peak loads, but a doubling of the slip distance from 17 cm to 38.5 cm corresponds to a reduction in peak load of about 1.4 kN, a 13% reduction for a 100% increase in elongation.
The factor-1 results are even less clear, with a 6.5 cm elongation resulting in a lower peak load than two 10 cm elongations and doing almost as well as one of the 12 cm elongations.
The knots in the test were first tightened under body weight, something that probably won't happen much of the time in climbing applications. One would expect less energy absorbtion in such cases.
In principle, the slipping of the knot under tension will absorb fall energy. How much depends on how much resistance the knot provides, and how that resistance changes as the knot slides. In practice, I don't see any evidence so far that knot slippage is a reliably significant source of energy absorbtion in the purcell prussik.
As for adjusting the Chain Reactor, the "correct" method is to use a second biner. I find it most convenient to clip this to the locking biner at the end of of the daisy.
|
|
|
|
|
knudenoggin
Jul 5, 2009, 3:39 AM
Post #23 of 26
(6740 views)
Shortcut
Registered: May 6, 2004
Posts: 596
|
rgold wrote: There are no comments in the write-up claiming that slippage results in energy absorbtion. The data is not particularly conclusive: ...
There is more to it than that, too: slippage under such loads screams
to me HEAT, and a big "OW" from the rope -- might you lower BOTH
the peak impact force and the breaking strength of the material?
Earlier you said that hi-mod stuff breaks under FF2 loads: not sure where
you get this, as I'm reminded of Kolin's testing of the infamous "Girth Hitch"
in webbing, and breaks there came only after holding a UIAA fall or two.
Moyer found a Sterling Vectran cord to not endure even a single UIAA fall,
but the other stuff he & Harmston tested in their paper held.
*kN*
|
|
|
|
|
majid_sabet
Jul 5, 2009, 3:26 PM
Post #24 of 26
(6708 views)
Shortcut
Registered: Dec 13, 2002
Posts: 8390
|
knudenoggin wrote: rgold wrote: There are no comments in the write-up claiming that slippage results in energy absorbtion. The data is not particularly conclusive: ... There is more to it than that, too: slippage under such loads screams to me HEAT, and a big "OW" from the rope -- might you lower BOTH the peak impact force and the breaking strength of the material? Earlier you said that hi-mod stuff breaks under FF2 loads: not sure where you get this, as I'm reminded of Kolin's testing of the infamous "Girth Hitch" in webbing, and breaks there came only after holding a UIAA fall or two. Moyer found a Sterling Vectran cord to not endure even a single UIAA fall, but the other stuff he & Harmston tested in their paper held. *kN*
Here are some images from drop test and how prussic loops interact with moving rope . The moving stance from the initial gripping to full stop is been marked.
double prussic vs static rope
Purcell prussic vs it's own 7mm cord
(This post was edited by majid_sabet on Jul 5, 2009, 3:28 PM)
|
|
|
|
|
vegastradguy
Jul 5, 2009, 4:01 PM
Post #25 of 26
(6698 views)
Shortcut
Registered: Aug 28, 2002
Posts: 5919
|
knudenoggin wrote: Earlier you said that hi-mod stuff breaks under FF2 loads: not sure where you get this, as I'm reminded of Kolin's testing of the infamous "Girth Hitch" in webbing, and breaks there came only after holding a UIAA fall or two. Moyer found a Sterling Vectran cord to not endure even a single UIAA fall, but the other stuff he & Harmston tested in their paper held. *kN*
Sterling Rope did some testing (and some other folks did as well, but the names escape me) and found that dyneema chains like the PAS tend to fail under FF2 loads due to their real lack of any stretch. I also believe that dyneema in general's lack of stretch makes it somewhat vulnerable to failure under sudden high loads (despite its ridiculous slow pull strength).
|
|
|
|
|
|
1
