Emergency backup ascenders, Petzl Tibloc?

[NZcaver]

IMHO, I like having gear that serves multiple purposes. Since I don’t cave with bottled beverages (biners will work as a church key if you do) I have never considered carrying a tiblock over soft rigging (prussic, bachman, etc) for emergency ascending.

Here’s why.

1. Short prussic cords or webbing loops serve well as leashes to carry ropes, clip rock hammers, hand drills, etc.

2. Longer accessory cord loops (like cordellete (sp?)) or lengths of webbing can be used to improvise rigging when needed.

3. Longer accessory cord loops or lengths of webbing can be used to rig hand lines when needed without sacrificing a rope required for another drop.

4. Longer accessory cord loops or lengths of webbing can be used with biners to rig up a quick and dirty small party crack & crevice rescue system.

Should I go on with the potential uses of longer accessory cord loops or lengths of webbing?

All perfectly valid comments - no argument about that.

Remember - Prusik cords and mechanical ascenders (including the Tibloc) need not be mutually exclusive. You can carry both, if you wish. (I do.) I believe the intent of fuzzy-hair-man's original post was to debate the pros and cons of each. And as previously discussed, there are situations where a Tibloc may work better than a Prusik, as well as vice-versa.

[NZcaver]

I just re-read my recent posts, and they make me sound like I'm on a one-man crusade against the Prusik knot!

Sorry. My intention is not to discredit the Prusik. I regularly use them in rigging/haul systems quite happily. I'm just trying to dispel that myth about Prusiks being totally reliable in all circumstances.

Carry on...

[hunter]

IMHO, I like having gear that serves multiple purposes. Since I don’t cave with bottled beverages (biners will work as a church key if you do) I have never considered carrying a tiblock over soft rigging (prussic, bachman, etc) for emergency ascending.

Here’s why.

1. Short prussic cords or webbing loops serve well as leashes to carry ropes, clip rock hammers, hand drills, etc.

2. Longer accessory cord loops (like cordellete (sp?)) or lengths of webbing can be used to improvise rigging when needed.

3. Longer accessory cord loops or lengths of webbing can be used to rig hand lines when needed without sacrificing a rope required for another drop.

4. Longer accessory cord loops or lengths of webbing can be used with biners to rig up a quick and dirty small party crack & crevice rescue system.

Should I go on with the potential uses of longer accessory cord loops or lengths of webbing?

Been away awhile, I though this thread had stopped...

I agree with the above and always carry prussik cord for pretty much these reasons,
although as I stated somewhere way back I do sometimes carry a tibloc as a backup ascendor, mainly because I am faster with it than with a prussik. My earlier comments were more that, given a prussik and a tibloc sitting next to each other as I setup my z rig I would choose the prussik because of my personal worries about the potential damage to the rope.

I just confirmed this story with a very credible eyewitness. Prusiks can strip the sheath from ropes. The NCRC has proved this in controlled testing - and no, unfortunately I still don't have any photos of it. Again, the issue goes back to the particular types, diameters, and conditions of the ropes and Prusik cords being used. Plus we are (of course) talking about significant loads being applied before damage occurs

.

Hey NZ,
I don't suppose you could enlighten us on the specifics? Maybe I should be carrying a different diameter and type of cord. I'm curious, is spectra one of the bad types?

James

[NZcaver]

I don't suppose you could enlighten us on the specifics? Maybe I should be carrying a different diameter and type of cord. I'm curious, is spectra one of the bad types?

PLEASE don't use Spectra for Prusiks! Yes, it's one of the bad types.

As I understand, Spectra is way too hard (rigid) to use for Prusiks. They slip easily, making them very awkward to use. And if you do get them to set - then subject them to a shock load or other large force - they'll probably cause significant damage to the rope. [Edit - replaced "break" with "damage" to pacify Hank]

I'm sorry, I still don't have the specifics on the testing I mentioned. Not very helpful, am I? The rope used was almost certainly an 11mm PMI. I'm just guessing, but I suspect the Prusiks in question might have been a little too thin and/or too rigid to handle the type of load applied. As I recall, the increasing (static) load caused the Prusik to grip tighter (as usual), but rather than doing the limited-slip thing it finally stripped the sheath.

However - keep this in perspective. That testing was meant to duplicate rescue loads in exceptional circumstances. If you carry 6mm Prusik cord (like I do) for personal use and single-person (static) loads, you should be fine on 11mm rope. Plus if you ever need to use them on thinner ropes (like 9 or 10mm), they should work well - where an 8mm Prusik cord might slip too easily.

You could always try some testing of your own. All you need is a little spare rope and cord, some steel rigging hardware, pulleys, a dynamometer (optional), a vehicle with a winch, and some big trees. Fun!

[NZcaver]

On the subject of Tiblocs... check out this video clip I stumbled across on YouTube.

Superbot in a Vertical Rope Climb

[hank moon]

As I understand, Spectra is way too hard (rigid) to use for Prusiks. They slip easily, making them very awkward to use. And if you do get them to set - then subject them to a shock load or other large force - they'll probably break the rope.

Huh? How is a Prusik gonna break the rope? Do tell!

[NZcaver]

As I understand, Spectra is way too hard (rigid) to use for Prusiks. They slip easily, making them very awkward to use. And if you do get them to set - then subject them to a shock load or other large force - they'll probably break the rope.

Huh? How is a Prusik gonna break the rope? Do tell!

Hank, I made that post a year ago.

Read back in the thread, where I talked about destruction testing Prusiks tied in small diameter cord. The sheath was damaged/stripped on the rope, proving that Prusiks are NOT fail-safe under all conditions. You even replied:

Prusiks can cause coreshots, but I have not seen this happen outside of severe drop tests conducted with rescue loads.

Near as I can recall (it HAS been a whole year, after all) I was meaning under these extreme conditions, using a small diameter Spectra cord Prusik could conceivably cause the rope to fail. That is all.

Did you enjoy watching that video in my link?

[fuzzy-hair-man]

As I understand, Spectra is way too hard (rigid) to use for Prusiks. They slip easily, making them very awkward to use. And if you do get them to set - then subject them to a shock load or other large force - they'll probably break the rope.

Huh? How is a Prusik gonna break the rope? Do tell!

I guess it depends which rope?

I don't know about breaking the rope but everything I've seen on Spectra/Dyneema cord has said not to use it for prussik loops because of it's 'slippy' nature and because it melts at a lower temperature than other rope materials and the prussik after slipping will melt and presumably break the prussik at lower forces than a prussik in regular accessory cord.

Beal:

100% dyneema accessory cord particularly suited to making foot loops and secondary anchors for caving. Never use to make self-locking knots (Melting point : 145 C)

Later they recommend thier 5.5mm dyneema for prussik loops but the 5.5mm seemsto have a regular sheath (Apparantly pure dyneema doesn't take a dye so is white) which I presume they hope you aren't going to melt through.

To make a sling we recommend the double fisherman’s knot, except for Dyneema cord, which requires a triple fisherman’s knot. For prusik loops we recommend the use of our 7mm accessory cord, or our 5.5mm Dyneema. Because Dyneema is very slippy, cords made from it present sheath slippage. For this reason they must not be used as the second line during abseil descents.

[hank moon]

Read back in the thread, where I talked about destruction testing Prusiks tied in small diameter cord. The sheath was damaged/stripped on the rope, proving that Prusiks are NOT fail-safe under all conditions.

ok, but let's make a distinction between "break the rope" and "break the sheath" The latter is preferred by most!

Did you enjoy watching that video in my link?

yah, talk about emergency use!

[NZcaver]

ok, but let's make a distinction between "break the rope" and "break the sheath" The latter is preferred by most!

My earlier post has now been edited, and this travesty is no more.

[John Lovaas]

Did you enjoy watching that video in my link?

yah, talk about emergency use!

Boy, I thought the climbing robot was neat, then I saw this video next to it-

http://www.youtube.com/watch?v=vr-RrpBDrDw

Talk about emergency ascending! ;-)

And as an on-topic item, I've been using a Tibloc as a third ascender. I Frog, and use my handled ascender as the QAS when I approach the lip for a rappel.

The thing that struck me about the Tibloc when I first saw it was its thinness- I've come up to super undercut lips before where the rope is absolutely flush against the rock above me, and working the upper ascender- or my "regular" QAS- up any distance could be a nightmare. The edge of the Tibloc is so thin, I can wiggle it under the pinned rope with very little difficulty, and get my attachment above the lip without anywhere near the cussing and swearing that is usually required.

Don't try this at home, or in a cave.

[wyandottecaver]

I have also read that spectra also has the unfortunate characteristic of "powdering" = disentigrate under severe shock loads. It also degrades rapidly which is why most bulletproof vests made of spectra style fibers get replaced regularly.

Prussiks can strip a sheath under very very high loads but they dont cut the rope itself like some mechanical cams.

Tblocs are a great backup, but unless you file the front teeth they are murder on ropes.

[NZcaver]

Tblocs are a great backup, but unless you file the front teeth they are murder on ropes.

It depends on how carefully you "set" the Tibloc each time. I would be cautious about filing the front teeth. This isn't to say it's necessarily a bad idea, just that you might need them if ever faced with an icy rope or some other difficult operating condition.

[wyandottecaver]

I should clarify that I dont file the front teeth away, just dull them a great deal. As for icy ropes, thats what my pee bottle is for :P J/k urine is BAD for rope.