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Scott McCrea
12-27-04 10:10 PM
Hot Knife Through Butter
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Recently, I did some testing to see how hard or easy it is to cut loaded rope.
Here's what I came up with: http://www.swaygogear.com/hotknife/
Enjoy. :)
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Ralph E. Powers
12-28-04 12:17 AM
Watchword of the Year... BE CAREFUL!
It certainly doesn't take much does it.
I've had to cut webbing with rescue weight on it but being CAREFUL to ensure I was cutting ONLY the webbing and NOT the rope we were on.
In the dark of the pit, probably tired, cold, wet, whatever, these conditions can impair judgement and thus a person needs to be sure of exactly what they're doing so not to suddenly drop because there isn't no second chance.
Redundant back-ups and safeties to the max if the decision to cut the rope comes into play.
Yeah fun stuff to watch and damn ed-yew-kay-sun-nall
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Faraway Ern
12-28-04 08:05 PM
Rope is like butter...at times
Â
Scott,
Thanks for sharing that great bit of info on the rope cutting. At the Vertical Section meetings, they used to show that in real life and it really makes a believer out of you. They'd ask for a few volunteers from the audience and you'd put three or four guys/gals on each end of a piece of BlueWater or PMI...or whatever, and then the demonstrator would casually walk up to the line and ask if they were really pulling on the rope. "Yep!" usually was the answer and then, he'd put his blade down on the center and all of the volunteers would go flying backwards, so...as Ralph mentioned, Be Aware! Be safe! Oh, yeah....BE CAREFUL! And, have a great caving experience in '05. ;)
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charliedog1965
03-03-05 09:59 PM
Very thought-provoking test you did on loaded rope. I have always tried to be sure to use rope guards when rappelling, due to seeing tests like this.
have you ever tried (or seen someone try) to cut a rope with a sharp edged rock?
That would drive the point home even more.
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Squirrel Girl
03-04-05 06:03 AM
Quote: Originally Posted by charliedog1965
have you ever tried (or seen someone try) to cut a rope with a sharp edged rock?
I just re-watched the video Scott and his buddies made, and the last demonstration was with a sharp rock. It took something like 14 rubs with a sharp rock to cut the rope. Let's see. If one step is about 8", then in about 9' of pit, you'd have cut the rope. Conditions vary, so that would be a rule of thumb based on the one example. It could be much better or much worse.
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charliedog1965
03-04-05 01:27 PM
oops!
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[QUOTE=Squirrel Girl]I just re-watched the video Scott and his buddies made, and the last demonstration was with a sharp rock.
I guess I didn't scroll down far enough. Great demonstation.
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RescueMan
03-04-05 11:04 PM
Quote: Originally Posted by Ralph E. Powers
In the dark of the pit, probably tired, cold, wet, whatever, these conditions can impair judgement and thus a person needs to be sure of exactly what they're doing ... if the decision to cut the rope comes into play.
There's a "teachable moment" story, I think in an early edition of Setnika's Wilderness Search & Rescue.
A couple of climbers on the Nose of El Capitan are rappeling back down after an epic 2000' climb. After several hot, exhausting rappels, they're down to about 1000' and the first on that pitch gets his t-shirt caught in his rappel device. He places a tiny brass micro-nut in a hairline crack just to keep him from spinning on the rope while he pulls out his knife and hacks away at his shirt.
Suddenly, to his horror, he sees the doubled climbing rope he's rapping on go springing up away from him and he finds himself dangling 1000' above the desert on a nut the size of a shirt button.
The rope is now too short for his partner to rap down to him, and there's no decent anchors anyway at that point to set up another rap station. So they do what anyone in that situation would do - SCREAMED AT THE TOP OF THEIR LUNGS until other climbers noticed them and set up a rescue.
They lived to tell the tale. But I doubt they were ever again so quick to open a knife anywhere near a loaded rope.
- Robert
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#12 Â
03-09-05, 04:00 PM
CaveStar
Guys dropping a new crack out here in mid-state (Washington State) area, sides of pit turn out to be a bit unstable, good-sized rock drops, nearly whacks caver on head, hits rope further down where rope touches wall of pit as wall deviates from straight; rock nearly cuts through rope. Fortunately, caver realizes something has happened (other than his own near-death experience), hauls up rope, sees damage, ties it out. So everybody gets to pass a knot.
So, yeah, these ropes are far from invulnerable. And it's this kind of stuff that really makes me not love skinny rope.
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#13 Â
03-09-05, 05:52 PM
ian mckenzie
Calgary, Canada
Your not-love is shared by lots of other cavers. On the flip-side, alpine-rigged skinny rope seldom (tempted to say 'never') touches the rock, and rope cannot be cut by falling rock unless it is lying against a hard surface (as in your example). Nor can it be cut by saw or bounce action if it does not touch.
Becoming comfortable with skinny rope goes hand-in-hand with becoming comfortable with a different style or ethic of rigging.
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#14 Â
03-09-05, 06:36 PM
Cheryl Jones
Virginia
After looking at Scott McCrea's knife through butter tests on his Web page, I'm amazed that over the decades of SRT that we haven't had (any? more?) caver deaths and injuries due to cut ropes.
Anyone know of a caver who has had his/her rope severly cut or cut through from abrasion or a knife?
__________________
Cheryl Jones
NSS Director
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 #15 Â
03-09-05, 06:51 PM
Squirrel Girl
Go "Beyond the Deep"
Quote: Originally Posted by Cheryl Jones
Anyone know of a caver who has had his/her rope severly cut or cut through from abrasion or a knife?
I, personally, had my rope cut clear through the sheath at Dante's Descent. About 200' off the deck the rope rubbed up against basalt and cut the sheath.
Dave Harrison walks with a cane (and has other health problems) after falling 45' or so at a grotto practice session near Denver. It had been raining, and his poncho got caught in his rack. He used a knife to cut the poncho and he took a quick trip to the ground. That happened in the early 80s or earlier.
__________________
Barbara Anne am Ende
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 #16 Â
03-09-05, 07:04 PM
Ralph E. Powers
Quote: Originally Posted by Cheryl Jones
Anyone know of a caver who has had his/her rope severly cut or cut through from abrasion or a knife?
I have a couple of experiences where rope rub has worn through the sheath completely or partially. These were unforseen rub-points in the sense that you hang the rope and it's okay, rappel down it, and it's still okay, then start ascending up and hey!, woah, yowza... weird how that works sometimes.
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 #17 Â
03-09-05, 08:59 PM
kd4goc
Tim White / Moderator
Not a cave…but the first time I visited Whiteside Mountain, NC in the mid-80’s to rappel and climb the 750ft. free drop of granite we had an occurrence of abrasion. Less than 200 feet from the top the rope touches the wall at a lip that requires a pad. As the first climber prepared to ascend the rope the wind whipped the rope off of the pad. He climbed not knowing this until he reached the breakover and saw that the sheath had been completely abraded away as well as some core strands of PMI Maxi-Wear. He tied-out the cut with a knot, wrapped the rope in the pad before I climbed. Berta and I routinely do this climb now, but have made custom pads in case of high winds.
In 1990 a caver climbing out of the 310 foot pit of Mega Well, AL fell to his death after the rope cut. Twenty feet from the lip the rope lays against a wall/ledge for 4 feet then is free. The rope he was using was of unknown European make, bought in Mexico. One caver ascended the rope before the 2nd climber, climbing with a frog system fell when the rope failed. The 10mm rope was rigged IRT, no rebelay.
Be safe,
Tim White <>< NSS 26949 RE FE
Editor, Nylon Highway
-------------------------------------
Southeastern Region Coordinator-
National Cave Rescue Commission, NSS
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 #18 Â
03-10-05, 07:01 PM
RescueMan
Quote: Originally Posted by kd4goc
The 10mm rope was rigged IRT, no rebelay.
There's an acronym I'm not familiar with. I don't suppose IRT means Interstate Rapid Transit? Or do you mean SRT?
- Robert
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 #19 Â
03-10-05, 07:48 PM
ian mckenzie
Calgary, Canada
"Indestructible Rope Technique", a/k/a SRD, "Sling a Rope Down".
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 #20 Â
03-10-05, 07:49 PM
pacaver
I think it means Indestructible Rope Technique, i.e. get a thick, strong rope and don't worry too much about padding, rebelays, etc.
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mgmills
03-10-05 07:52 PM
Maybe it is a regional -TAG- terminology
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IRT = Indestructable Rope Technique
Wrap the tree and throw it down the hole.
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daisy
03-10-05 08:58 PM
yikes!
Â
Great movie! That rock was scary!
I was on a trip years ago to an open air 250' pit when a rope almost got cut by rock abrasion. It was sheer luck the climber wasn't killed. The lip of the pit is sandstone (very abrasize). We had two ropes in the pit, both padded. However, one pad had a hole in it -- I recall some discussion about the holey ropepad as we were rigging, and the consensus was "oh it's fine, just make sure the last one down makes sure the rope's not on the hole". Everyone rappelled down. One person who wasn't caving that day stayed up at the top of the pit. One climber started climbing on a frog system (very bouncy). The rope evidently shifted so it was resting right over the hole in the ropepad. The person at the top of the pit wandered over to check on everyone's progress and noticed that the rope was rubbing right on the rough sandstone lip through the hole in the pad -- and the rope was getting very fuzzy! She yelled at the climber to stop and finally managed to communicate that the climber needed to get off the rope. The climber got off rope (I think she changed over to the other rope). The sheath was completely abraded and strands of the core had been abraded.
So there's another good lesson for proper padding techniques! I've been pretty fanatical about proper padding ever since that experience.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
RescueMan
03-11-05 06:54 PM
Quote: Originally Posted by daisy
We had two ropes in the pit, both padded. However, one pad had a hole in it ... and the rope was rubbing right on the rough sandstone lip through the hole in the pad.
Too many stories about ropes shifting off of rope pads. To be safe, use a velcro-closure, wrap-around rope protector like this:
You can also improvise with a piece of old canvas fire hose, though these need to be slipped over the end of the rope before tying off.
- Robert
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ian mckenzie
03-11-05 10:35 PM
We use those velcro'd tubes up here, but the knot in the cord is along the side rather than at the top so you can make a prussik knot to attach them to the rope. You could use the cord to attach the tube to the rock if the rope is bending over an edge. Others I've seen have an oversized alligator clip so that you can attach-detach it from the rope quickly, which makes them much easier to pass.
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Ralph E. Powers
03-11-05 10:50 PM
Quote: Originally Posted by ian mckenzie
We use those velcro'd tubes up here, but the knot in the cord is along the side rather than at the top so you can make a prussik knot to attach them to the rope. You could use the cord to attach the tube to the rock if the rope is bending over an edge. Others I've seen have an oversized alligator clip so that you can attach-detach it from the rope quickly, which makes them much easier to pass.
Those velcro-ed tubes ARE good but sometimes can be a pain to get on/off rope, I use them where-ever the rope touches the rock above the attachment point and below the anchor.
I do use the medium sized black binder clips which grip the rope just so without crushing it, also I use wide pieces of low shag carpeting (office and apartment types) dispite someone's hue and cry over the fact that it's nylon rubbing on nylon... there's not that much movement on the rope to be that much of a problem. I've never seen any immediate (or long term) damage to either rope or "pad" doing this. I'll also use old demin pants legs for padding as well. I tend to blow holes in the knees of most of my jeans so I have a continual supply.
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Ralph E. Powers
03-11-05 10:51 PM
Quote: Originally Posted by mgmills
IRT = Indestructable Rope Technique
Wrap the tree and throw it down the hole.
We do that too here, only we've learned that it's best to thread a long piece of tubular webbing over the rope to protect the bark on the tree... just another method of conservation here. :good:
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madratdan
03-12-05 09:19 AM
Quote: Originally Posted by Ralph E. Powers
We do that too here, only we've learned that it's best to thread a long piece of tubular webbing over the rope to protect the bark on the tree... just another method of conservation here. :good:
We use old fire hose. If you check with the local fire dept. you may be able to talk them into giving you some. We also put it on all of our permanently placed hand lines and repel ropes. My girlfriend split some 4" and sewed velcro to it so you can wrap it around a rope. I then added a grommet and a prussick to help keep it in place and make it easy to pass and reset it. Fire hose makes the best rope pads.................
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Ralph E. Powers
03-12-05 01:53 PM
Quote: Originally Posted by madratdan
We use old fire hose. If you check with the local fire dept. you may be able to talk them into giving you some. We also put it on all of our permanently placed hand lines and repel ropes. My girlfriend split some 4" and sewed velcro to it so you can wrap it around a rope. I then added a grommet and a prussick to help keep it in place and make it easy to pass and reset it. Fire hose makes the best rope pads.................
Totally agreed... now if the stuff wasn't so heavy.
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