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cracklover
Feb 25, 2011, 6:28 PM
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sp115 wrote: cracklover wrote: ...Anyway, you're still missing the point. Webbing may be better, but it can still get sliced if it moves around under tension. Yup, and I'm not convinced it is better than rope. (see the last reply to this post on the other site) http://www.mountainproject.com/...06990414#a_106990769
Wow, thanks for that link! Pretty definitive, I'd say!
GO
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taydude
Feb 25, 2011, 6:35 PM
Post #27 of 45
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sungam wrote: qwert wrote: While redundancy is generally a good thing, there are time when it simply is not neccessary, or will not work. And i would dare to say that 2ft trees are one of those cases. What do you guess will happen when one of the big trees you anchored to will fail? A few tonnes of wood will fall down towards the earth or the cliff side. I havent yet calculated it or measured it, but falling trees produce quite a lot of force. I have managed to knock over other trees with a falling tree, or to simply completely unroot them, so i guess there is a lot of force involved. And even if your backup tree and the conncetion to it withstands the other trees fall, try to imagine what will happen if said tree still connected to the other tree swipes over the cliffside. Again, i havent calculated it, but i imagine a bloody smear all over the cliff, that once was a climber ... qwert The translation sucks a little but here is a report of some Norwegian climbers that ripped one of the trees in their anchor. They weren't 2-footers but pretty sizable (at least a foot). Carnage. http://www.ClimbNorway.blogspot.com/2008/april/23/zeefernfailen
That was.... tricky... 
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ClimbSoHigh
Feb 25, 2011, 7:25 PM
Post #28 of 45
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Thanks SP!
This is an eye opener to me, as I was taught otherwise. I have heard from multiple climbers that webbing distributes the force better than rope, but this is not true according to this test. http://www.xmission.com/~tmoyer/testing/Qualifying_a_Rescue_Rope.pdf.
I stand corrected, and will inform my partners who taught me this. I wish I left in my original post that I had only learned this and have not seen any lab tests to support it. Now I have and am shocked at the severity of the results.
The conclusion of the report for thoese too lazy to read it is.. "The test results for webbing make very clear what we have known for a long time. For rock anchors, if there is any possibility that an anchor could shift when it is loaded, webbing should not be used. If it is used on rock, edges should be well padded."
The test performed though was testing webbing vs different 7/16 static lines which is clearly far superior. I would assume the 3/8 is also clearly supperior based on the strengh ratings specs, but I wonder how the test results would work with a similar rated cord say 8mm acc cord vs 1" tubular which are comperativly rated. The linked forum claims that the webbing is still significantly weaker than 8 mm cord but the test that was cited only compares 7/16 static ropes with 1" tubular webbing. The webbing did however last up to 1800 lbs of force for the dead weight cut test.
Thank you for the informative post. I tried to do a quick seach for tests between 8mm cord and 1" webbing and did not get anything, so I am taking the lazy way out and asking if anyone here knows of one? The physics of webbing dispersing the load over the entire inch compared to 1 small point still makes sense to me but I could still be very wrong.
I think I might go destroy some old 8mm cord and webbing for my own amusement and to see for myself. One thing I do know is that webbing is very popular for TR anchors and 8mm cord used as a single strand is not, so maybe the physics still holds true about the force distribution...
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sp115
Feb 25, 2011, 7:37 PM
Post #29 of 45
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cracklover wrote: sp115 wrote: cracklover wrote: ...Anyway, you're still missing the point. Webbing may be better, but it can still get sliced if it moves around under tension. Yup, and I'm not convinced it is better than rope. (see the last reply to this post on the other site) http://www.mountainproject.com/...06990414#a_106990769Wow, thanks for that link! Pretty definitive, I'd say! GO
Yeah, and completely counter to what I had been taught and heard repeated for years.
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sherpa79
Feb 25, 2011, 8:32 PM
Post #30 of 45
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patmay81 wrote: in a top rope scenario your anchor is holding the climber and belayers weight. you should not by any means anchor to a fallen tree. look for a bfr, cracks for pro, etc. Assume the tree weighs 1,000 lb (probably more, maybe less). I can personally move that much weight (rolling, dragging etc.) take into account that most cliffs have a slope at the top, you get gravity contributing. If you find a dead tree lodged in a crevace or crack (acting like a chock), I'd be comfortable with that, but no free lying trees. Its not a matter of weight, but possition and security of your BFT/BFR/BFA.
I wasn't suggesting using a fallen tree perse, just a thought experiment as to the types of forces involved. I was suggesting thinking moreso than any anchoring practice. Allthough, building a deadman anchor is a common skill in canyoneering and in snow. A thousand pound weight on the ground is nothing but, depending of course on its position, as you pointed out. I work as a professional arborist, with about 75% of my time on the climbing side of things. Believe me, I have plenty of experience moving heavy A$$ wood around  as well as dealing with the types of forces a tree can and can't take.
I will say, though, that a 2 inch tree is pretty small for a solitary TR anchor. Especially at any cliff line I've ever been to. Will it fail, maybe not, but as previously mentioned the depth of soil, species, and even the amount of rain recently can make a difference in small trees that are poorly rooted (as they can often be) right at a cliff's edge. I've partially uprooted stuff that big just by pulling on it while climbing through it. But, I've also slung 2" stuff along the way and felt confident in it.
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esander4
Feb 25, 2011, 8:40 PM
Post #31 of 45
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Cprosser16 wrote: Would it be safe enough to set up one tree anchor that is well made on an excellent tree and extended over the edge of the cliff? In reply to: I know not to place the rope over the edge In reply to: I know you were talking about the anchor part of the system. Your drawing was unnecessary, it did not contribute to teaching me. I knew about the set up already
Why ask if you already knew?
In reply to: In the OP I just needed to know if using multiple trees was necessary.
And cracklover answered your question.
In reply to: I know how to make the anchors
No, you don't. Period.
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Cprosser16
Feb 27, 2011, 4:47 PM
Post #32 of 45
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First off, I see now there has been some confusion. Cracklover, you and I are talking about two different ropes, when talking about the anchor system you drew. I was talking about the climbing rope. I know not to have the climbing rope bent over the edge of the cliff in anyway. The anchor system I know is supposed to be extended over the edge for this very reason, but to keep the anchor WEBBING (not rope, therein lies the confusion) from abrading or slicing I am using rugs (large rugs) over the area that the webbing could move in. Although I don't suspect the webbing to move at all, the climbs I wish to climb are all fairly centered below the trees I am going to be use. The cliff too has no chance of slicing the webbing or rope. It is not so much a definite edge as it is an ever increasing slope the closer you get the the "edge".
Another thing, I know what you meant by your drawing and how you thought it would help, but the reason it didn't is because as I stated earlier, there are not any trees at the angle, or any angle close to that, in the area. At least none that would be good for anchoring. The area has about 10 good sized trees and 10 smaller trees with hundreds of saplings interspersed. I thank you for the drawing and the information, but what you have said does not apply to my specific situation.
As for esander4, who are you to say that I don't know how? I have made anchors before, just not with a single tree as the sole anchor. I have had someone who has 15+ years of climbing experience check my anchors when he taught me how to make them. We both used them to climb with. I know what I am doing. Period.
I have all the information that I originally asked for plus some, thanks to all those who ACTUALLY contributed.
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USnavy
Feb 28, 2011, 7:41 AM
Post #33 of 45
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cracklover wrote: Don't take this lightly. One swinging fall could mean curtains. It's very easy to cut a rope under tension. Edited to add the following quote from a guy who makes ropes at Sterling. This is in regards to the "sharp edge test" used to certify some ropes: In reply to: After the edge standard was introduced I did a bunch of tests using an actual piece of broken granite as the edge. Even with a fall factor WAAAYYYY below 0.5 none of the certified ropes held. Later I resorted to simply lowering the 80kg onto the rope without dropping. Once the rope was fully loaded with the mass I allowed the rope to roll slightly across the edge. Again none of the ropes held. <snip> The broken piece of granite was pretty damned sharp but I could easily walk up to any granite cliff and find edges that are sharper. GO
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JimTitt
Feb 28, 2011, 8:22 AM
Post #34 of 45
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We have been setting up working ropes for years over the sharpest sea-eroded limestone you can possibly ever imagine, a length of 6mm flexible stainless cable with swaged eyes is the answer.
Or if itīs not too extreme I use a cloth covered lifting strop- they are cheap, robust and tested over sharp edges under load.
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j_ung
Feb 28, 2011, 8:53 PM
Post #36 of 45
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cracklover wrote: Ugh... typical half-assed responses. One big tree is plenty strong enough. Your problem is that if the route wanders, you will be scraping the TR anchor rope or webbing all over the place. If the lip of the clifftop has any sharp edges, your anchor rope will certainly get hung up on it. Much better to do something like this:  The blue line is the anchor material, the red is the climbing rope. The small tree is what's known as a "directional". If you set it up right the little tree won't have to hold much force (a little less than half) but it will keep the anchor material from moving around over the clifftop. Cheers, GO
I don't normally find such a directional to be necessary. I look for a good notch or irregularity at the lip to do the exact same job. Also, it's worth noting that your directional can't be some twig sticking out of the ground (that's hyperbole for all the literal people out there). It has to be a fully functional anchor point, or you may just create more problems than you solve.
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qwert
Mar 1, 2011, 8:29 PM
Post #37 of 45
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JimTitt wrote: Or if itīs not too extreme I use a cloth covered lifting strop- they are cheap, robust and tested over sharp edges under load.
I assume strop = strap
And then? cloth covered?
I think i know what you could mean, but i cant really make sense of your description.
qwert
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JimTitt
Mar 1, 2011, 10:24 PM
Post #38 of 45
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They are the continous loop slings (thatīs a strop) rather than the lifting straps with eyes in the end used for general lifting and stuff and are covered in coarse canvas with the working load stamped on it. Inside are the cores.
They sell them in OBI amongst other places, about 5 for a 1000kg rated one and they are robust as hell!
Jim
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Adk
Mar 3, 2011, 12:01 AM
Post #40 of 45
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Great find !!!
Yet not conclusive as stated due to the number of variables. It's a general guide and a good one at that. It's a good read.
Since white pine failure was just below the 5" mark and these tests were performed on southern grown species, yes Kentucky is south, in the north I'd be willing to bet that the shift would be closer to at least an inch less for the hardwood species.
Let's be honest, white pine is going to bend that 10 degrees just about anywhere.
This is one report that I will be passing on!
Thanks
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JimTitt
Mar 3, 2011, 6:23 PM
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Looks like in the lifting industry they are called "round slings" which is fair enough I guess.
Plenty of examples on this link http://www.liftsafesolutions.co.uk/id75.html
Jim
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alexv54
Mar 10, 2011, 1:43 PM
Post #43 of 45
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i have been looking online for weeks if it was possible to use these as top rope anchors, as i'll be buying two for slacklining and i was hoping they could double duty for me. thanks!
what would be the best way to rig this up off a tree?
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JimTitt
Mar 10, 2011, 3:55 PM
Post #44 of 45
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Good for slacklining as they protect the tree well but Iīm not sure Iīd carry them around just for tying to tree, I just tie the rigging rope around with a bowline or a normal sling.
Jim
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