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dingus


Nov 10, 2009, 9:52 AM
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Re: [johnwesely] An anchor to analyze [In reply to]
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johnwesely wrote:
hansundfritz wrote:
bennydh wrote:
...and what does it mean to fail anyway... death maybe, but death is a new beginning; you can come back as an eagle... or a dragon!

Sounds like something a belayer should never shout up as encouragement to the cruxed-out leader.

I was climbing an R/X rated route once, and about half way up, my belayer yelled up, "If you fall here you are seriously going to die". I yelled back down, "I know that, but thanks for breaking my concentration". He knew from the outset that there was no pro on the route.

I want to know if I am leading and I feel compelled to tell, if partner is leading, when the X-threshold is crossed.

DMT


dugl33


Nov 10, 2009, 9:57 AM
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Re: [kachoong] An anchor to analyze [In reply to]
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kachoong wrote:
dugl33 wrote:
4.) gear is old -- old style .75 camalot, rigid stem friend.

dugl33 wrote:
Finally the load swings to the .75 old school camalot, which, despite its apparantly bomber appearance, also pulls, with no apparent benefit from the load already reduced by the failure of the upper pieces.

Why you hatez on the U-stem? Whyz? I have one and use it in anchors.

Got nUtthin bUt lUv for the U stems!





Of course, zee U stems are semi retired...



Yet if I really needed three in a given size...



I wouldn't hesitate to pull the u-stems out of the misc. extra crap bag, put it on the rack, climb above it, and lob onto it ... yippee.

Of course, if its the only thing keeping me off the deck, I'd go for the newer one first.

Cool
Attachments: u_stems.JPG (113 KB)
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johnwesely


Nov 10, 2009, 10:05 AM
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Re: [dugl33] An anchor to analyze [In reply to]
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The U stem Camalots have to be the ugliest cams ever made. That probably has something to do with the stigma.


johnwesely


Nov 10, 2009, 10:09 AM
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Re: [dingus] An anchor to analyze [In reply to]
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dingus wrote:

I want to know if I am leading and I feel compelled to tell, if partner is leading, when the X-threshold is crossed.

DMT

It usually distracts me and breaks my focus, but I usually try to avoid routes like that unless I can climb then with a swarm of yellow jackets in my face.


dingus


Nov 10, 2009, 10:10 AM
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Re: [johnwesely] An anchor to analyze [In reply to]
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Well if you know what you're about I can respect that! Sometimes a bloke gets into those things unawares though....

Cheers
DMT


johnwesely


Nov 10, 2009, 10:14 AM
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Re: [dingus] An anchor to analyze [In reply to]
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dingus wrote:
Well if you know what you're about I can respect that! Sometimes a bloke gets into those things unawares though....

Cheers
DMT

That is when it is nice to pretend you are not in those situations.


kachoong


Nov 10, 2009, 10:35 AM
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Re: [johnwesely] An anchor to analyze [In reply to]
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johnwesely wrote:
dingus wrote:

I want to know if I am leading and I feel compelled to tell, if partner is leading, when the X-threshold is crossed.

DMT

It usually distracts me and breaks my focus, but I usually try to avoid routes like that unless I can climb then with a swarm of yellow jackets in my face.

Heh... litmus yellow jacket test.


evanwish


Nov 10, 2009, 10:58 AM
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Re: [jt512] An anchor to analyze [In reply to]
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jt512 wrote:
johnwesely wrote:
The biggest issue is that Jay probably set the thing up himself.

I didn't set the anchor up. It was an actual top rope anchor set up by another climber, as I wrote in the OP.

Jay

you know these types of posts get flamed a lot, but i really like them.



but anyway i'd say does not meet the SRENE standards (if that's what you use)
Solid: probably
Redundant: Only in one crack feature (eh whatever, not bad) and the gates are not in opposition.
Equalized: NO.
Non Extension: it will shock load the biners and especially the one going to the top nut.

someone needs to just go buy some slings


(This post was edited by evanwish on Nov 10, 2009, 11:04 AM)


subantz


Nov 10, 2009, 11:07 AM
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Re: [jt512] An anchor to analyze [In reply to]
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I see two draws clipped together big NO NO. I believe they could be equalized better also. But the quikdraws linked together from the biners. I would have not jumped on that. Also the gates on the rope end are not opposing. So no I give this set up a F for fucked up!


seatbeltpants


Nov 10, 2009, 11:30 AM
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Re: [jt512] An anchor to analyze [In reply to]
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jt512 wrote:
reno wrote:
kylekienitz wrote:
reno wrote:
"What percentage of risk am I, personally, willing to accept?"

Personally I don't see much reason to risk it for TR.

That's the rub, though... Risk WHAT?

Would you accept a TR anchor with a 1% chance of total failure? A 2% chance? 3? Where is your line?

That's the question. There is no answer that fits all.

While risk is a personal matter, you guys are off of what is rationally acceptable by several orders of magnitude. It would be insane to accept a 1% chance of a TR anchor failure. That would more-or-less guarantee that practically every climber who TRs on a regular basis would die or be critically injured due to TR failure during his TR career. For comparison, sport parachutes have a failure rate of about 1/1000, and you carry two of them; so your chances of dying on any given jump are on the order of one chance in 1 million.

Jay

YES.

screw climbing on an anchor that has a 1% chance of blowing - but i'm terrified that some posters seem to have no worries climbing on an anchor that has a 1 in 5 chance of blowing?! russian roulette, anyone?

steve


dugl33


Nov 10, 2009, 12:49 PM
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Re: [subantz] An anchor to analyze [In reply to]
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Acceptable, but not perfect. Equalization not perfect, but no shock loading. And of course, 2 biners, opposed at the master point.



Better (although not really redundant, unless done with two equal sized slings, and 2 biners, opposed, at the master point. Note the knot to limit shock loading extension.




Another good alternative. No shockloading, perfectly equalizing within a reasonable range of pull angles.




(This post was edited by dugl33 on Nov 10, 2009, 12:54 PM)
Attachments: climbing_anchors_unequal_cordellete.jpg (54.5 KB)
  sliding_anchor1.jpg (22.0 KB)
  sliding_anchor2.jpg (16.5 KB)
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glytch


Nov 10, 2009, 1:08 PM
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Re: [dugl33] An anchor to analyze [In reply to]
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dugl33 wrote:
Acceptable, but not perfect. Equalization not perfect, but no shock loading. And of course, 2 biners, opposed at the master point.

[Inline climbing_anchors_unequal_cordellete.jpg]

I don't know where this diagram came from, but, unfortunately, there just isn't anything true about it. The loads on pieces connected via a knotted cordalette are not inversely proportional to their strand lengths.

I don't see the need to rehash the hundreds of pages of discussion rc.com has seen on the topic of equalized (or non-equalized) anchors, but thinking of cordalettes in the way represented by the above diagram is misleading. Cordalettes tied in that way, in the real world, load exactly one piece at a time unless the direction of pull is perfectly, perfectly aligned in such a way as to weight two pieces. Weighting all three simultaneously, is, I reckon, well nigh impossible.


(This post was edited by glytch on Nov 10, 2009, 1:09 PM)


boku


Nov 10, 2009, 2:07 PM
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Re: [glytch] An anchor to analyze [In reply to]
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glytch wrote:
...I don't know where this diagram came from, but, unfortunately, there just isn't anything true about it...

I believe that the diagram came from a later edition of Largo's (John Long's) book on climbing anchors. It is the result of tests of forces distributed through real-world climbing anchors. Largo, I know that there are huge threads about this methodology reassessment, can you please chime in here?

At issue is that everything bends, everything stretches. Nothing, not even diamond or carbon nanotubes, is perfectly stiff. Any mechanical engineer worth their pay knows that the largest, strongest bolt is nothing but a very tightly wound spring.

Given two springs that differ only in length (same materials, same coil OD, same number of coils per inch), the shorter spring is always stiffer (deflects less under the same load) than the longer spring.

In reply to:
...Cordalettes tied in that way, in the real world, load exactly one piece at a time unless the direction of pull is perfectly, perfectly aligned in such a way as to weight two pieces...

Glytch, that statement is true only for completely inelastic cordage. If you have some of that, can you please send it to me or Aric for pull testing?

You can easily replicate the effect demonstrated in the diagram with different lengths of lightweight bungee cord. The shorter pieces of bungee will be stiffer than the longer pieces, and will therefore transmit more force to their respective anchors.

Thanks, Bob "BoKu" K.


(This post was edited by boku on Nov 10, 2009, 2:16 PM)


dugl33


Nov 10, 2009, 2:14 PM
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glytch wrote:
I don't know where this diagram came from, but, unfortunately, there just isn't anything true about it. The loads on pieces connected via a knotted cordalette are not inversely proportional to their strand lengths.

Well, this all getting a bit academic, no doubt, but I believe there was some load testing done with cordelletes which show exactly this tendency.

Under heavy loads, even static cord will stretch some. Longer cord stretches a greater overall distance than shorter cord, with the overall effect being more load is taken on the pieces with the shorter loops.

(put your jugs on 200 feet of rope and pull the slack out until it takes your weight, and compare this to the slack you take out when on 100 feet of rope, if you're bored or whatever)

Yes, we're assuming the load is in line with the resultant vector algebra of the dealy-hoo.

At the end of the day, if the pieces are solid, I'm totally comfortable with the cordellete method. Just thought I'd throw some visuals in the action, as everyone is worked up by the scandalous equalization / redundancy issues of the exhibit.


mojomonkey


Nov 10, 2009, 2:18 PM
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Re: [boku] An anchor to analyze [In reply to]
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That anchor needs a tire.

(This thread made me wonder how Majid is doing...)


glytch


Nov 10, 2009, 2:28 PM
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Re: [boku] An anchor to analyze [In reply to]
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boku wrote:
glytch wrote:
...I don't know where this diagram came from, but, unfortunately, there just isn't anything true about it...

I believe that the diagram came from a later edition of Largo's (John Long's) book on climbing anchors. It is the result of tests of forces distributed through real-world climbing anchors. Largo, I know that there are huge threads about this methodology reassessment, can you please chime in here?

At issue is that everything bends, everything stretches. Nothing, not even diamond or carbon nanotubes, is perfectly stiff. Any mechanical engineer worth their pay knows that the largest, strongest bolt is nothing but a very tightly wound spring.

Given two springs that differ only in length (same materials, same coil OD, same number of coils per inch), the shorter spring is always stiffer (deflects less under the same load) than the longer spring.

You can easily replicate the effect demonstrated in the diagram with different lengths of lightweight bungee cord. The shorter pieces of bungee will be stiffer than the longer pieces, and will therefore transmit more force to their respective anchors.

Thanks, Bob "BoKu" K.

I don't have a copy of the most recent climbing anchors - my understanding was that Largo's most recent tests demonstrated that any static "equalization," in reality, wasn't equalized.

Your point about the ability of any material to stretch/deform is well taken and absolutely correct. The diagram as presented makes sense, in that context, if the loading force is exactly in the direction which loads each strand of the cordalette. My objection centers on those cases in which the the direction of pull does not engage all of the strands at the outset of the fall/whatever. In such a case, any equalization happens only through the stretch of the cordalette, and unless the angle of pull is within a still narrow range, the full force of the fall will be held by the first piece to load. The less stretchy the material, the wider the range of single-piece-taking-the-whole-fall is.

But, I think we're in agreement about this! Thanks for the thoughtful post...


glytch


Nov 10, 2009, 2:36 PM
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Re: [dugl33] An anchor to analyze [In reply to]
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dugl33 wrote:
Yes, we're assuming the load is in line with the resultant vector algebra of the dealy-hoo.

Post timing overlap! The post I just made notes that this is where the issue with a cordalette lies - any load sharing is critically dependent on a combination of stretchy cord and having a load in line with the resultant vector dealy-hoo. Essentially, the cordalette only distributes loads between pieces when loaded at a very specific range of angles.

Like you, I still use knotted cordalettes with some frequency, most often because I have directional pieces which are happiest when pulled in a certain direction... and I believe that bomber pieces are the key to a safe anchor no matter what.

Sorry for the unnecessarily strong reaction to your original post - I thought you were implying that a cordalette dynamically equalizes among pieces, and that's evidently not what you were implying.


dugl33


Nov 10, 2009, 3:13 PM
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Re: [glytch] An anchor to analyze [In reply to]
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glytch wrote:
Sorry for the unnecessarily strong reaction to your original post - I thought you were implying that a cordalette dynamically equalizes among pieces, and that's evidently not what you were implying.

Hey, no worries. This is all in the realm of thought experiments (which sounds more noble than cyberslacking)...

Regarding angles of pull, with a TR anchor 100' above the ground, even standing 10' to one side of the plumb line, the angle between strands is only about 6 degrees when the climber hangs on the rope. The vector load on the anchor's master point being halfway between the top rope strands in this case is therefore, only 3 degrees. So, for most TR, imperfect directional loading is of minor consequence, if the cordellete is simply tied in line with an imaginary plumb line. At least gravity is predictable Cool


(This post was edited by dugl33 on Nov 10, 2009, 3:24 PM)


reno


Nov 10, 2009, 8:25 PM
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Re: [seatbeltpants] An anchor to analyze [In reply to]
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seatbeltpants wrote:
screw climbing on an anchor that has a 1% chance of blowing - but i'm terrified that some posters seem to have no worries climbing on an anchor that has a 1 in 5 chance of blowing?! russian roulette, anyone?

It must be comforting to do all your climbing on rock that is 100% solid, with all the gear you could possibly need to construct an anchor that is 100% safe from any possible chance of failure.

That sort of climbing has nothing in common with the kind of rock/ice/alpine/mountain climbing I've ever seen and done.

Maybe it's just me, but every anchor I've ever seen has potential to fail. Some have more potential than others.


(This post was edited by reno on Nov 10, 2009, 8:28 PM)


the_leech


Nov 10, 2009, 8:36 PM
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Re: [bennydh] An anchor to analyze [In reply to]
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bennydh wrote:

Percentages whaaaa? All this thinking inside the box with narrow minded logic. Why not try to will the safety margins in your favor. If you will the send to happen, and your sending chi is centered, you eliminate all risk.

...and what does it mean to fail anyway... death maybe, but death is a new beginning; you can come back as an eagle... or a dragon!

Eagles are kewl.

Dragons are kewler.

Even dingus's fucking kids would agree.


jt512


Nov 10, 2009, 8:53 PM
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Re: [reno] An anchor to analyze [In reply to]
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reno wrote:
seatbeltpants wrote:
screw climbing on an anchor that has a 1% chance of blowing - but i'm terrified that some posters seem to have no worries climbing on an anchor that has a 1 in 5 chance of blowing?! russian roulette, anyone?

It must be comforting to do all your climbing on rock that is 100% solid, with all the gear you could possibly need to construct an anchor that is 100% safe from any possible chance of failure.

That sort of climbing has nothing in common with the kind of rock/ice/alpine/mountain climbing I've ever seen and done.

Maybe it's just me, but every anchor I've ever seen has potential to fail. Some have more potential than others.

I can count on my fingers the number of times I've climbed on an anchor that at least a 1% chance of failing, and still have 10 fingers left over. I have a feeling you could, too.

Jay


(This post was edited by jt512 on Nov 10, 2009, 8:55 PM)


Partner robdotcalm


Nov 10, 2009, 8:54 PM
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Re: [dugl33] An anchor to analyze [In reply to]
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dugl33 wrote:
kachoong wrote:
dugl33 wrote:
4.) gear is old -- old style .75 camalot, rigid stem friend.

dugl33 wrote:
Finally the load swings to the .75 old school camalot, which, despite its apparantly bomber appearance, also pulls, with no apparent benefit from the load already reduced by the failure of the upper pieces.

Why you hatez on the U-stem? Whyz? I have one and use it in anchors.

Got nUtthin bUt lUv for the U stems!





Of course, zee U stems are semi retired...



Yet if I really needed three in a given size...



I wouldn't hesitate to pull the u-stems out of the misc. extra crap bag, put it on the rack, climb above it, and lob onto it ... yippee.

Of course, if its the only thing keeping me off the deck, I'd go for the newer one first.

Cool

The problem with u-stem Camalots is that they fail below their rated strength. It's not a matter of esthetics.

http://www.rockclimbing.com/...ring=u-stem;#2023370

Cheers,
Rob.calm


dingus


Nov 11, 2009, 10:41 AM
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Re: [seatbeltpants] An anchor to analyze [In reply to]
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seatbeltpants wrote:
jt512 wrote:
reno wrote:
kylekienitz wrote:
reno wrote:
"What percentage of risk am I, personally, willing to accept?"

Personally I don't see much reason to risk it for TR.

That's the rub, though... Risk WHAT?

Would you accept a TR anchor with a 1% chance of total failure? A 2% chance? 3? Where is your line?

That's the question. There is no answer that fits all.

While risk is a personal matter, you guys are off of what is rationally acceptable by several orders of magnitude. It would be insane to accept a 1% chance of a TR anchor failure. That would more-or-less guarantee that practically every climber who TRs on a regular basis would die or be critically injured due to TR failure during his TR career. For comparison, sport parachutes have a failure rate of about 1/1000, and you carry two of them; so your chances of dying on any given jump are on the order of one chance in 1 million.

Jay

YES.

screw climbing on an anchor that has a 1% chance of blowing - but i'm terrified that some posters seem to have no worries climbing on an anchor that has a 1 in 5 chance of blowing?! russian roulette, anyone?

steve

There is no valid number you can assign to that anchor or any other anchor. Probability of failure is a guessing game in the extreme and mostly pointless.

Better to express as a feeling, than a number. Whether its 1 in a hundred or 1 in 10,000 or 1 in a million its really nothing more than a feeling expressed as a number by folks who J delights in pointing out have no real knowledge of stats anyway.

Based on what I see in that pic? That anchor has virtually nil chances of failing, despite all the 'best practices' cited here to convince me otherwise.

Almost no chance at all. What's that... 1 in a million Doc? 1 in ten million???

DMT


dingus


Nov 11, 2009, 10:44 AM
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jt512 wrote:
I can count on my fingers the number of times I've climbed on an anchor that at least a 1% chance of failing, and still have 10 fingers left over. I have a feeling you could, too.

Jay

I'd dare say you've never climbed on any anchor where the probability of failure was more than opinion. Now I would accept your opinion as a matter of faith... and even be willing to stake my life on it (If you tell me your anchor is good I would believe it face value (and still inspect it when I got there hehe)).

But expressing it as a number is just a way of stating opinion, nothing more.

DMT


dugl33


Nov 11, 2009, 10:59 AM
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robdotcalm wrote:
The problem with u-stem Camalots is that they fail below their rated strength. It's not a matter of esthetics.
http://www.rockclimbing.com/...ring=u-stem;#2023370

Cheers,
Rob.calm

First off, thanks for the redirect. I hadn't seen this thread and its pretty interesting stuff...

A few thoughts, though:

First, yes the specific units tested failed below the rated strength. But is this due to:

1.) passage of time and weakening of materials?

2.) different test methodology?
a. different load duration and conditions?
b. different coefficient of friction on the plates?
c. smaller test sample
d. different chosen expansion point (crack width)
e. strain gauge calibration?
d. some other difference...

Not saying the testing is invalid at all, just saying we can't time machine that gear back to the exact same test conditions.

It is interesting to note that some of the units simply slid out, without mechanical failure, yet still held 1000 lbs + before doing so. This is actually reassuring to me. Ultimately it is friction counteracting the load. Metal plate seems slicker than snot compared to the friction of most sandstone or granite.

I have seen people pull gear somewhere around 8 or 9 times. I can't think of a single one of these times where the gear itself was broken upon inspection. Not saying it hasn't happened, just saying I haven't witnessed it.

Of the badly mangled gear I've seen, it held the fall in question, and was usually placed in a funky manner such as perpendicular to the angle of the fall. I guess it had to hold enough force to mangle itself.

Unplaced gear holds precisely 0 KN

9 - 10KN is not an insignificant amount of holding power. Stoppers, I believe, are rated around this level. Something squirrely is going on if you are generating 9 KN on your top rope anchor. Perhaps you are using static line and there is slack in the line when the climber drops?

As mentioned, these pieces for me are on the B team, and spend most of their time on the bench. It is dangerous to put too much faith in any one piece of the chain anyway. The consequences of anchor failure are so severe that most of us face it by being as bomber as possible.

Jay is right, several orders of magnitude to the safe side is appropriate rather than a ludicrous 20% russian roulette anchor. We've mostly all been in dicey situations, realized it was dicey, and did our best not to test our luck by falling on it... but it would be very hard to justify a dicey TR anchor.

camalot info:
http://www.youtube.com/watch?v=_ivM-qoQDlM


(This post was edited by dugl33 on Nov 11, 2009, 5:32 PM)

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