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Terry2124
Apr 15, 2009, 6:53 PM
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diebetes wrote: Terry2124 wrote: diebetes wrote: shockabuku wrote: Terry2124 wrote: rocknice2 wrote: This would be better if the loop around the tree was bigger and the knots were fig8's. Most important this is only 1/2 or 1/3 of bomber anchor. Don't rely on any one sling or biner in your anchor setups.......REDUNDANCY is key I agree, fig 8 doesn't weaken a rope as much as a water knot. Make sure to have redundancy It's (clearly) not a rope, it's webbing. A water knot is the appropriate choice for webbing. Glad I'm not the only one who thinks this. From what I see on the pics he is not joining the ends together. I know its webbing and you can still use a fig 8 on webbing. Water knots have a bit of slippage. http://en.wikipedia.org/wiki/Water_knot In the end the point is having redundancy. No matter what the knot if something fails it equals doom. ***Redundancy*** You can also tie a BFK in webbing; just because you CAN do something does not mean that you SHOULD. Take some webbing and tie two knots- a retraced figure 8 and a water knot, and tell me that the water knot doesn't make more sense.
Look at the picture and then use your brain and think about it. Whatever knot can work. What is wrong with the pic is no redundancy ( back up in case webbing breaks )
You are just so focused on the knot used that you don't see the big picture of the actual anchor system. Why not double the webbing or even tie both ends using water knot then its like a sling, then tie a knot at the tree and biner, this way its like 2 slings are there and therefore if a section gets cut the anchor will not fail.
Get passed the actual knot. Majid indicated using a. V. Which would also be better.
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kachoong
Apr 15, 2009, 6:58 PM
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majid_sabet wrote: acorneau wrote: TimothyMark wrote: I should clarify - I wouldn't climb on that as my only anchor. The setup that we used had 2 trees, and 2 lengths of webbing. Each piece of webbing was tied off like the picture indicates (retraced overhand). Assuming there is little chance of the webbing cutting over a sharp edge, then I'd say you're good to go. 1" webbing is good for about 4,000 lbs. single strand. Water knot/overhand reduces the ultimate strength by ~30-35%, so you're good for ~2500 lbs. (~11kN) per anchor. 2 of these anchors gives you roughly 5,000 lbs. (~22kN) of strength (assuming your angle between the two is less than 60 degrees or so). All rough numbers, but you get my point. no he is not good for 2500 lbs at 10:1 safety factor, his rig in a good day is rated to 250 lbs max
I don't think the OP was suggesting using this for rescue purposes nor making sure it was within SAR guidelines.... besides... this is the beginners forum, no?
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kachoong
Apr 15, 2009, 7:02 PM
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jfitzpat wrote: acorneau wrote: Assuming there is little chance of the webbing cutting over a sharp edge, then I'd say you're good to go. Doubled up, I'd agree. I prefer static line, it's more durable and harder to sever. Also, I'd still prefer more 'v' at the tree (less force on the knot) and I would clip both biners through both runs of webbing (seperate, they tend to 'saw' back and forth on the edge as you belay and the climber moves side to side). But even without those tweaks, I'd top rope on a redundant version.
I like to use static line also... and do three wraps of the tree with the end tied in an eight and clipped to the load strand with a locker.
...and of course equalized with at least another tree with the same setup.
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Factor2
Apr 15, 2009, 7:13 PM
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majid_sabet wrote: no he is not good for 2500 lbs at 10:1 safety factor, his rig in a good day is rated to 250 lbs max
and then if you use a 20:1 safety factor It's only good for 125 pounds. Dear god, that's not even my body weight. None of us should be climbing on these
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kennoyce
Apr 15, 2009, 7:19 PM
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In reply to: no he is not good for 2500 lbs at 10:1 safety factor, his rig in a good day is rated to 250 lbs max
you're totally right majid, but I'd like you to name even one piece of climbing gear that is not strictly rescue oriented that has a 10:1 safety factor for even a short lead fall.
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diebetes
Apr 15, 2009, 7:38 PM
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Terry2124 wrote: diebetes wrote: Terry2124 wrote: diebetes wrote: shockabuku wrote: Terry2124 wrote: rocknice2 wrote: This would be better if the loop around the tree was bigger and the knots were fig8's. Most important this is only 1/2 or 1/3 of bomber anchor. Don't rely on any one sling or biner in your anchor setups.......REDUNDANCY is key I agree, fig 8 doesn't weaken a rope as much as a water knot. Make sure to have redundancy It's (clearly) not a rope, it's webbing. A water knot is the appropriate choice for webbing. Glad I'm not the only one who thinks this. From what I see on the pics he is not joining the ends together. I know its webbing and you can still use a fig 8 on webbing. Water knots have a bit of slippage. http://en.wikipedia.org/wiki/Water_knot In the end the point is having redundancy. No matter what the knot if something fails it equals doom. ***Redundancy*** You can also tie a BFK in webbing; just because you CAN do something does not mean that you SHOULD. Take some webbing and tie two knots- a retraced figure 8 and a water knot, and tell me that the water knot doesn't make more sense. Look at the picture and then use your brain and think about it. Whatever knot can work. What is wrong with the pic is no redundancy ( back up in case webbing breaks ) You are just so focused on the knot used that you don't see the big picture of the actual anchor system. Why not double the webbing or even tie both ends using water knot then its like a sling, then tie a knot at the tree and biner, this way its like 2 slings are there and therefore if a section gets cut the anchor will not fail. Get passed the actual knot. Majid indicated using a. V. Which would also be better.
You tell me to think about the big picture, then you say ignore the knot. The knot is part of the system isn't it?
The reason I am concerned with the knot is for more than just ascetic reasons- the more bends in the material, the weaker the knot. That, and water knots are easier to tie, assuming you know both knots well. I've never read any literature on materials and knots that even suggested using a figure 8 on webbing.
It's a shame that because of your argument you can't reply to this. I mean, get over the knot.
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Terry2124
Apr 15, 2009, 8:31 PM
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diebetes wrote: Terry2124 wrote: diebetes wrote: Terry2124 wrote: diebetes wrote: shockabuku wrote: Terry2124 wrote: rocknice2 wrote: This would be better if the loop around the tree was bigger and the knots were fig8's. Most important this is only 1/2 or 1/3 of bomber anchor. Don't rely on any one sling or biner in your anchor setups.......REDUNDANCY is key I agree, fig 8 doesn't weaken a rope as much as a water knot. Make sure to have redundancy It's (clearly) not a rope, it's webbing. A water knot is the appropriate choice for webbing. Glad I'm not the only one who thinks this. From what I see on the pics he is not joining the ends together. I know its webbing and you can still use a fig 8 on webbing. Water knots have a bit of slippage. http://en.wikipedia.org/wiki/Water_knot In the end the point is having redundancy. No matter what the knot if something fails it equals doom. ***Redundancy*** You can also tie a BFK in webbing; just because you CAN do something does not mean that you SHOULD. Take some webbing and tie two knots- a retraced figure 8 and a water knot, and tell me that the water knot doesn't make more sense. Look at the picture and then use your brain and think about it. Whatever knot can work. What is wrong with the pic is no redundancy ( back up in case webbing breaks ) You are just so focused on the knot used that you don't see the big picture of the actual anchor system. Why not double the webbing or even tie both ends using water knot then its like a sling, then tie a knot at the tree and biner, this way its like 2 slings are there and therefore if a section gets cut the anchor will not fail. Get passed the actual knot. Majid indicated using a. V. Which would also be better. You tell me to think about the big picture, then you say ignore the knot. The knot is part of the system isn't it? The reason I am concerned with the knot is for more than just ascetic reasons- the more bends in the material, the weaker the knot. That, and water knots are easier to tie, assuming you know both knots well. I've never read any literature on materials and knots that even suggested using a figure 8 on webbing. It's a shame that because of your argument you can't reply to this. I mean, get over the knot.
Well looks like I just replied to this!
Don't you find it strange that you only talk about the knot and nothing else, no redundancy, no doubling up, no extra webbing, the actual structure of the anchor...........
I do see you like to tie easy knots, I bet your running shoes have velcro straps.
Shoo troll, you have not given any constructive information as how to make this anchor more safe.
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uni_jim
Apr 15, 2009, 8:45 PM
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calm down children. You can play nicely can't you?
in rope, a figure eight on a bight is preferred, but an overhand on a bight can do the same job. In webbing, an overhand/water/other variation of the same knot is preferred, but a figure eight can do the same job.
now go back to your pudding.
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Lazlo
Apr 15, 2009, 9:06 PM
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uni_jim wrote: calm down children. You can play nicely can't you? in rope, a figure eight on a bight is preferred, but an overhand on a bight can do the same job. In webbing, an overhand/water/other variation of the same knot is preferred, but a figure eight can do the same job. now go back to your pudding.
Mmm. Puddin'.
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Factor2
Apr 15, 2009, 9:16 PM
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Terry2124 wrote: diebetes wrote: Terry2124 wrote: diebetes wrote: Terry2124 wrote: diebetes wrote: shockabuku wrote: Terry2124 wrote: rocknice2 wrote: This would be better if the loop around the tree was bigger and the knots were fig8's. Most important this is only 1/2 or 1/3 of bomber anchor. Don't rely on any one sling or biner in your anchor setups.......REDUNDANCY is key I agree, fig 8 doesn't weaken a rope as much as a water knot. Make sure to have redundancy It's (clearly) not a rope, it's webbing. A water knot is the appropriate choice for webbing. Glad I'm not the only one who thinks this. From what I see on the pics he is not joining the ends together. I know its webbing and you can still use a fig 8 on webbing. Water knots have a bit of slippage. http://en.wikipedia.org/wiki/Water_knot In the end the point is having redundancy. No matter what the knot if something fails it equals doom. ***Redundancy*** You can also tie a BFK in webbing; just because you CAN do something does not mean that you SHOULD. Take some webbing and tie two knots- a retraced figure 8 and a water knot, and tell me that the water knot doesn't make more sense. Look at the picture and then use your brain and think about it. Whatever knot can work. What is wrong with the pic is no redundancy ( back up in case webbing breaks ) You are just so focused on the knot used that you don't see the big picture of the actual anchor system. Why not double the webbing or even tie both ends using water knot then its like a sling, then tie a knot at the tree and biner, this way its like 2 slings are there and therefore if a section gets cut the anchor will not fail. Get passed the actual knot. Majid indicated using a. V. Which would also be better. You tell me to think about the big picture, then you say ignore the knot. The knot is part of the system isn't it? The reason I am concerned with the knot is for more than just ascetic reasons- the more bends in the material, the weaker the knot. That, and water knots are easier to tie, assuming you know both knots well. I've never read any literature on materials and knots that even suggested using a figure 8 on webbing. It's a shame that because of your argument you can't reply to this. I mean, get over the knot. Well looks like I just replied to this! Don't you find it strange that you only talk about the knot and nothing else, no redundancy, no doubling up, no extra webbing, the actual structure of the anchor........... I do see you like to tie easy knots, I bet your running shoes have velcro straps. Shoo troll, you have not given any constructive information as how to make this anchor more safe.
you know, if you hadn't been so busy advocating the wrong knot to use, you might have noticed that the OP posted this
In reply to: I should clarify - I wouldn't climb on that as my only anchor. The setup that we used had 2 trees, and 2 lengths of webbing. Each piece of webbing was tied off like the picture indicates (retraced overhand). Those aren't my photos, they're just the only photos that I could find illustrating this setup.
This thereby ends the need for redundancy discussions, leaving the knot free to be discussed.
Repetition helps kids learn
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majid_sabet
Apr 15, 2009, 9:34 PM
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kennoyce wrote: In reply to: no he is not good for 2500 lbs at 10:1 safety factor, his rig in a good day is rated to 250 lbs max you're totally right majid, but I'd like you to name even one piece of climbing gear that is not strictly rescue oriented that has a 10:1 safety factor for even a short lead fall.
if you want to teach a new climber on how to rig an anchor then you have to provide them with whatever is the best. rigging a half as* cord around a tree with a Mickey mouse knot that is to close to the biner's gate is not a good way to help a n00b.
This is how people learn a wrong thing and that is why they fall to their death and die cause they keep following a Mickey mouse recommendations by other so called “experienced" climbers.
Do it right, build it safe and climb in comfort.
10:1 safety factor
20 KN anchor or better
proper edge protection
proper sling and knot
proper biner
BFA
And so fort
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diebetes
Apr 15, 2009, 9:39 PM
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Factor2 wrote: Terry2124 wrote: diebetes wrote: Terry2124 wrote: diebetes wrote: Terry2124 wrote: diebetes wrote: shockabuku wrote: Terry2124 wrote: rocknice2 wrote: This would be better if the loop around the tree was bigger and the knots were fig8's. Most important this is only 1/2 or 1/3 of bomber anchor. Don't rely on any one sling or biner in your anchor setups.......REDUNDANCY is key I agree, fig 8 doesn't weaken a rope as much as a water knot. Make sure to have redundancy It's (clearly) not a rope, it's webbing. A water knot is the appropriate choice for webbing. Glad I'm not the only one who thinks this. From what I see on the pics he is not joining the ends together. I know its webbing and you can still use a fig 8 on webbing. Water knots have a bit of slippage. http://en.wikipedia.org/wiki/Water_knot In the end the point is having redundancy. No matter what the knot if something fails it equals doom. ***Redundancy*** You can also tie a BFK in webbing; just because you CAN do something does not mean that you SHOULD. Take some webbing and tie two knots- a retraced figure 8 and a water knot, and tell me that the water knot doesn't make more sense. Look at the picture and then use your brain and think about it. Whatever knot can work. What is wrong with the pic is no redundancy ( back up in case webbing breaks ) You are just so focused on the knot used that you don't see the big picture of the actual anchor system. Why not double the webbing or even tie both ends using water knot then its like a sling, then tie a knot at the tree and biner, this way its like 2 slings are there and therefore if a section gets cut the anchor will not fail. Get passed the actual knot. Majid indicated using a. V. Which would also be better. You tell me to think about the big picture, then you say ignore the knot. The knot is part of the system isn't it? The reason I am concerned with the knot is for more than just ascetic reasons- the more bends in the material, the weaker the knot. That, and water knots are easier to tie, assuming you know both knots well. I've never read any literature on materials and knots that even suggested using a figure 8 on webbing. It's a shame that because of your argument you can't reply to this. I mean, get over the knot. Well looks like I just replied to this! Don't you find it strange that you only talk about the knot and nothing else, no redundancy, no doubling up, no extra webbing, the actual structure of the anchor........... I do see you like to tie easy knots, I bet your running shoes have velcro straps. Shoo troll, you have not given any constructive information as how to make this anchor more safe. you know, if you hadn't been so busy advocating the wrong knot to use, you might have noticed that the OP posted this In reply to: I should clarify - I wouldn't climb on that as my only anchor. The setup that we used had 2 trees, and 2 lengths of webbing. Each piece of webbing was tied off like the picture indicates (retraced overhand). Those aren't my photos, they're just the only photos that I could find illustrating this setup. This thereby ends the need for redundancy discussions, leaving the knot free to be discussed. Repetition helps kids learn
Huh...
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rocknice2
Apr 15, 2009, 11:18 PM
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majid_sabet wrote: acorneau wrote: TimothyMark wrote: I should clarify - I wouldn't climb on that as my only anchor. The setup that we used had 2 trees, and 2 lengths of webbing. Each piece of webbing was tied off like the picture indicates (retraced overhand). Assuming there is little chance of the webbing cutting over a sharp edge, then I'd say you're good to go. 1" webbing is good for about 4,000 lbs. single strand. Water knot/overhand reduces the ultimate strength by ~30-35%, so you're good for ~2500 lbs. (~11kN) per anchor. 2 of these anchors gives you roughly 5,000 lbs. (~22kN) of strength (assuming your angle between the two is less than 60 degrees or so). All rough numbers, but you get my point. no he is not good for 2500 lbs at 10:1 safety factor, his rig in a good day is rated to 250 lbs max
If he uses 2 sling then @ 10:1 he's safe to 500lbs.
even @ 250 lbs that's about what the largest male climber I've ever met weighs.
10:1 is way overkill safe, 5:1 is considered safe.
There is no question that the sling is strong enough to hold the largest of asses.
Nevertheless shit happens like abrasion, edge cut, psycho squirrels, etc, etc.
We as climber don't calculate what an anchor can hold in terms of Lbs or Kn because the gear is all rated to hold.
We calculate in terms of redundancy and this is 2:1 or 3:1 to be safe
If OP is setting this up regularly then a static line is very desirable.
(This post was edited by rocknice2 on Apr 15, 2009, 11:31 PM)
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majid_sabet
Apr 16, 2009, 4:47 AM
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rocknice2 wrote: majid_sabet wrote: acorneau wrote: TimothyMark wrote: I should clarify - I wouldn't climb on that as my only anchor. The setup that we used had 2 trees, and 2 lengths of webbing. Each piece of webbing was tied off like the picture indicates (retraced overhand). Assuming there is little chance of the webbing cutting over a sharp edge, then I'd say you're good to go. 1" webbing is good for about 4,000 lbs. single strand. Water knot/overhand reduces the ultimate strength by ~30-35%, so you're good for ~2500 lbs. (~11kN) per anchor. 2 of these anchors gives you roughly 5,000 lbs. (~22kN) of strength (assuming your angle between the two is less than 60 degrees or so). All rough numbers, but you get my point. no he is not good for 2500 lbs at 10:1 safety factor, his rig in a good day is rated to 250 lbs max If he uses 2 sling then @ 10:1 he's safe to 500lbs. even @ 250 lbs that's about what the largest male climber I've ever met weighs. 10:1 is way overkill safe, 5:1 is considered safe. There is no question that the sling is strong enough to hold the largest of asses. Nevertheless shit happens like abrasion, edge cut, psycho squirrels, etc, etc. We as climber don't calculate what an anchor can hold in terms of Lbs or Kn because the gear is all rated to hold. We calculate in terms of redundancy and this is 2:1 or 3:1 to be safe If OP is setting this up regularly then a static line is very desirable.
one think you need to remember is that you should always build an anchor for the worse situation. worse situation is when climber A raps down and gets banged by a rock and now hangs in mid air with his gri gri and climber B raps down on climber's A anchor to save him but then he shock load the entire system on his daisy while trying to lower climber A. That is when you go above 250 lbs. or safety factor of 10:1
(This post was edited by majid_sabet on Apr 16, 2009, 6:21 AM)
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james481
Apr 16, 2009, 5:43 AM
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I love how you jump to these conclusions (like the anchor would have ripped had the climber not decked at JT) without any reason for doing so (just like you did in that recent helmet thread, and countless others). I understand that you're a rescue guy, and, as such, it's ingrained into you that you should build titanically strong anchors for those types of situations. The fact is, we're talking about a top rope anchor here, and if you find yourself in a situation where you have two climbers hanging on such an anchor, and one "shock loads it with his daisy", then several mistakes not related to the anchor have already been made. True, in a perfect world, we would build all our anchors so that they could hang a dump truck and five climbers with strength to spare, but that's just not how things work in the world outside of rescue.
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bill413
Apr 16, 2009, 1:33 PM
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majid_sabet wrote: one think you need to remember is that you should always build an anchor for the worse situation. worse situation is when climber A raps down and gets banged by a rock and now hangs in mid air with his gri gri and climber B raps down on climber's A anchor to save him but then he shock load the entire system on his daisy while trying to lower climber A. That is when you go above 250 lbs. or safety factor of 10:1
And climber A (and B) were rapping why?
And, how did climber B get onto the rope to rap when climber A was weighting it? Let alone be able to move with what is essentially a full fireman's belay on the line.
"On his daisy" - ummm...how did that get introduced to the system?
Just some questions about the scenario.
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jamincan
Apr 17, 2009, 12:57 AM
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bill413 wrote: majid_sabet wrote: one think you need to remember is that you should always build an anchor for the worse situation. worse situation is when climber A raps down and gets banged by a rock and now hangs in mid air with his gri gri and climber B raps down on climber's A anchor to save him but then he shock load the entire system on his daisy while trying to lower climber A. That is when you go above 250 lbs. or safety factor of 10:1 And climber A (and B) were rapping why? And, how did climber B get onto the rope to rap when climber A was weighting it? Let alone be able to move with what is essentially a full fireman's belay on the line. "On his daisy" - ummm...how did that get introduced to the system? Just some questions about the scenario.
I think he meant that Climber B setup a rap on a separate rope, but using the same anchor. I have no idea why they would be rapping on a top rope either.
I have used a similar setup to the OP several times. I doubled up so that anchor was off two separate trees and I left a larger V and left longer tails on the water knots. It is quite useful in certain situations. In this particular case, I was setting up a top rope at Rattlesnake Pt. You are not allowed to sling the cedars, which are the predominate clifftop vegetation. This means that on many routes, you have to use quite a bit of webbing, even using this method, to setup a top rope, as you have to be more selective with the trees. Fortunately, the Conservation Authority has started a program to bolt the anchors for the top of routes, and this will no longer be an issue in the future.
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rocknice2
Apr 17, 2009, 2:38 AM
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One spectra sling achieves your 10 to 1 safety factor.
again it's quantitative redundancy that is needed, it's not a question of qualitative.
Although the quality of pro needs to be good too.
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knudenoggin
Apr 17, 2009, 3:43 AM
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The most redundancy we're seeing in this discussion is the gratuitous
copying of prior posts, to add all of one more line or few
--we saw it the first time, and if it was good, might've read
it over for thought; if not, repeating it won't help anyway.
Fac tor2 wrote:
Terry2124 wrote:
diebetes wrote:
Terry2124 wrote:
diebetes wrote:
Terry2124 wrote:
diebetes wrote:
shockabuku wrote:
Terry2124 wrote:
rocknice2 wrote:
{{{> yadda-yadda: score a point for me, please! <}}}
On the knots:
(1) Note that the Overhand & Fi g.8 eyeknots in webbing can be oriented
so that the mainline lies exterior or interior (the ones in the OP
lie interior). My best surmise is that this orientation is if at
all less secure and maybe weaker--but testing hasn't been very good
in knotting, so we don't have anything to go by. (In The Lab,
an interior break is shown for the Water Knot, in ONE sample;
but then so too is a "blue tape breaks again" failure, so ... .)
Tying the Overhand EK in the bight is easy to orient either way;
but tying it by tracing is more difficult to tie with the end lying
interior (as, well, one must work inside of the traced Overhand).
(2) Quoting Wikipedia's brief blurb about slippage on cyclic loading
is going nowhere because:
(2a) it concerns the Water knot (in tape), an ends-joining knot,
not an eyeknot (which is loaded on 2-vs.-1 strands, not 1-vs.-1);
(2b) it reports ONE test done for ONE particular material
(Tom privately showed to me a follow-up test done in HMPE tape and
1" tubular: the latter did NOT slip; neither slipped after bearing
significant load; the other testers conjectured that stiffness in
the material might make the knot vulnerable to slippage (which might
indicate a difference between new vs. aged 1" tubular, e.g..)
The slippage only occurred at lowish loading, not if the knot had
been loaded more heavily. --more a concern for rap than TR anchors.
(2c)NB: It was the EXTERIOR end--only--that slipped (hence my devising
the "Symmetric Water Knot for Tape", tested & not-so-well depicted
in a thread in The Lab (it should be/look SYMMETRIC--both ends
lying interior).)
(3) There are conflicting results for strength of Fig.8 vs. Overhand
in rope ; but seldom can you learn what the exact orientation
of the knots at test are (interior/exterior, and so on).
E.g., the CMC Rope Rescue Manual gives TWO cases of Fig.8, both in
rope and tape--"with a bight", "rewoven": there's a 4 %-pt difference
in tape (1 %pt for rope; avg. of 5 tests). Now, who would even THINK
to consider the tying method relevant? --unless its relevance is
called out explicitly in how it affects the final geometry
(such as with an Overhand EK in tape tied by tracing most likely
putting the mainline interior) !? But there it is,
and not only in CMC's book but also Dave Richards's testing
(just 3 ropes; minor diff.s).
*kN*
[edited to enumerate 1-2(abc)-3 vs 1-3(ab)-4 (oops)]
(This post was edited by knudenoggin on Apr 17, 2009, 2:44 PM)
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bill413
Apr 17, 2009, 12:21 PM
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knudenoggin wrote: (3a) it concerns the Water knot (in tape), an ends-joining knot, not an eyeknot (which is loaded on 2 vs. 1 strands, not 1 vs. 1); (3b) it reports ONE test done for ONE particular material
I'll add another data point for the Water knot slipping in 1 inch tubular webbing under cycling loads, but with low loading.
(N.B. I usually try & cut the quotes down to relevant size.  I do sometimes worry that I might be changing the meaning of a statement, and try to be good about that.)
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rtwilli4
Apr 17, 2009, 4:13 PM
Post #46 of 61
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Registered: Feb 14, 2008
Posts: 1867
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I would TR on it, but I wouldn't teach one of my clients that it was a good anchor.
Also, remember that water knots do slip and a fatty bouncing around on TR is a good way to get them to slip. I would at least back up the knots and would definitely not leave it as a permanent anchor.
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desertwanderer81
Apr 17, 2009, 4:47 PM
Post #47 of 61
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Registered: Sep 5, 2007
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majid_sabet wrote: acorneau wrote: TimothyMark wrote: I should clarify - I wouldn't climb on that as my only anchor. The setup that we used had 2 trees, and 2 lengths of webbing. Each piece of webbing was tied off like the picture indicates (retraced overhand). Assuming there is little chance of the webbing cutting over a sharp edge, then I'd say you're good to go. 1" webbing is good for about 4,000 lbs. single strand. Water knot/overhand reduces the ultimate strength by ~30-35%, so you're good for ~2500 lbs. (~11kN) per anchor. 2 of these anchors gives you roughly 5,000 lbs. (~22kN) of strength (assuming your angle between the two is less than 60 degrees or so). All rough numbers, but you get my point. no he is not good for 2500 lbs at 10:1 safety factor, his rig in a good day is rated to 250 lbs max
My god, will you please stop spreading around this steaming pile of misinformation???
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geargeek13
Dec 2, 2009, 9:05 PM
Post #48 of 61
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Registered: Dec 2, 2009
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A climber weighing 250 pounds hanging (not even falling) in a "sling shot top rope" will exert 500 pounds of force on the anchor above. Remember to keep 250 pounds from falling the belayer must also pull 250 pounds on the belay side of the rope. 250+250=500. (it is basically a 2:1 pulley!) If you were belaying from the top, directly off the anchor, a 250 pound object would exert 250 pounds on the anchor. If the person falls more than a few feet, they will generate even more force.
I prefer using webbing in a complete closed loop. yes you will use more webbing, but it is considerably stronger, it is more professional (There is a reason all prestiched webbing is in a loop!), and it lessens the stress on the knot. Pick up any rock climbing manual and you will see all webbing (even 1" tubular) tied in a complete loop. Experienced climbers do calculate (or at least understand) the forces an anchor or any piece of climbing gear can hold as not all climbing equipment is created equal.
At the very least, you need to add another leg to the anchor for redundancy purposes.
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