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sarcat
May 24, 2004, 2:31 PM
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I have to agree with philbox. Girth hitches are never to be used in any kind of anchor situation. The bend of the rope around itself reduces it's strength. To keep the 95% rope/webbing strength any 180 deg. redirection must be 4x the diamiter of the rope. Also a girth violates the no angle more than 60 deg. rule. A wrap 3 pull 2 could have worked on the tree and given more length to the anchor (pitch pine argument aside).
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vertical_reality
May 24, 2004, 2:39 PM
Post #52 of 70
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Something else I noticed that I'd correct if I were there was the girth hitch around the tree. It should be rotated counter clockwise to that the load bearing end is tangent with the tree. I don't know how much of a difference it would make but it would decrease the stress on the rope by getting rid of the bend in the loaded end.
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vegastradguy
May 24, 2004, 2:48 PM
Post #53 of 70
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That camalot is a bit shallow for me. I'd probably try one size smaller and try to place it deeper (assuming the crack gets smaller as it goes deeper). I guess it really depends on how solid or crumbly that rock tends to be.
The TCU is impossible to judge, although it does look nice and deep, so...its probably okay.
As for the overhand, like Jay, it's okay for a TR. Its not ideal, and Jay is correct, a clove hitch is a MUCH better choice...not only is it stronger, its also adjustable. Tying a grapevine there is silly....far too much work.
The anchor is okay for TR...not great, not really that good, but okay.
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fitzontherocks
May 24, 2004, 4:01 PM
Post #54 of 70
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Hard to tell, but the power point doesn't seem to go straight down. The direction the anchor could be loaded could cause the cordelette to rub against that very rough ledge, fraying or cutting it.
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luke
May 26, 2004, 7:06 PM
Post #56 of 70
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OK, I understand that the pitch pines are a problem, but otherwise this anchor is fine as far as can be seen in the picture. An EDK is not ideal under those circumstances, it could be improved, but at worst it will roll once or twice (under fairly large loads, even in that kind of cord) and tighten up and lock. That wouldnt happen unless the rest of the anchor failed because there wouldnt be large enough forces involved even to make it roll. I dont like having it inside the biners but it doesnt look like it will open them, in fact quite the opposite. The girth hitch will reduce the strength of the cordalette by 40% or whatever, but that is bluewater titan cord as far as I can see, rated to more than 3000 pounds. Drop it to 60% of its strength and you have 1800 pounds, which is probably stronger than those trees.
It is hard to see the cam placements or to know if the plates can be trusted, but whoever said that the black cam is too small to trust is a bit off. Maybe you meant a different brand (alien??), but that looks like a black metolius to me and if so is the size of a 3/4 camalot. The small metolius cams are grey and purple.
Of course it is fair to say that we can see ways this anchor could be improved, but the only things that might make it unsafe (cam placements, rock strength) are not detectable here.
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qwert
May 27, 2004, 10:04 AM
Post #57 of 70
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The only thing i consider as wrong (apart from the forbidden pines) is the knot in the biner. Apart from this, the knot seems really good. As i see it it is an overhand with long strands comming out of it, so no need to call it death knot :x
From my experience trees of this size will be sufficient for toproping purposes, but i would back it up though (another tree).
qwert
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taino
Jun 10, 2004, 7:16 PM
Post #58 of 70
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I went back last week to build a TR anchor on that same spot, for the same route. Sadly, I didn't have a camera available to take pictures.
Those cams in the original picture were, in fact, most likely undercammed. The two cracks there are MUCH more shallow than I'd suspected, and flared out where the pieces were placed. The lower, black cam looked to be better than the top one.
I ended up making an anchor using a purple tricam placed in active-mode under a huge boulder about 15 feet away for one leg of the anchor, and three other pieces in those cracks - in different places than were shown in the picture. I put in two pieces and connected them with their own mini-cordalette (4'sling, redundant magic x), then a third piece as the last leg. I avoided using the trees completely. To tie all three (four) sections together, I used 40' of static line in a "web-o-lette" configuration - a backed-up fig8-bight at each end clipped into a piece, with the middle run through the third piece and the centers pulled into the classic cordalette anchor configuration. This was extended past the edge and tied into a powerpoint.
Next time, I'll try to have a camera available.
T
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climbfrog
Jun 13, 2004, 7:17 AM
Post #59 of 70
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1. There is a vertical crack above the TCU placement. This would cause the rock to be weaker at this point, and the TCU would just make the rock expand, and possibly break.
2. The #1 Camalot is too shallow, and it looks as though the crack is flairing. Tri-cams would've been better instead of SLCD's.
3. The tree is girth hitched. This will reduce the strength of the cord up to 50%. The knot will reduce the strength a further 30%. There is a knot resting on the biners. You are using 6 mill cord. It's too weak for a TR set-up. 6mill cord has a breaking strength of 800 kilos. Minus the 30% for the knot equals 560 kilos. Now there is a breaking strength of 560kilos left. Minus 50% for the girth hitch equals a breaking strength of 280 kilos. Thats too weak. Tube tape is stronger.
4. I would tied the two trees off seprately, just in case one goes. Pad the trees.
5. The edge the cordelette is resting on, is not protected.
6. The rock doesnt seem to be of the best quality, judging by the small stones imbedded in it.
I would'nt expect too much from this set-up. Sorry man. The whole system would be a bit better if 11mill static line where used. It will be far stronger, and it takes less time to rig.
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coldclimb
Jun 13, 2004, 9:13 AM
Post #61 of 70
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In reply to: 1. There is a vertical crack above the TCU placement. This would cause the rock to be weaker at this point, and the TCU would just make the rock expand, and possibly break. 2. The #1 Camalot is too shallow, and it looks as though the crack is flairing. Tri-cams would've been better instead of SLCD's. 3. The tree is girth hitched. This will reduce the strength of the cord up to 50%. The knot will reduce the strength a further 30%. There is a knot resting on the biners. You are using 6 mill cord. It's too weak for a TR set-up. 6mill cord has a breaking strength of 800 kilos. Minus the 30% for the knot equals 560 kilos. Now there is a breaking strength of 560kilos left. Minus 50% for the girth hitch equals a breaking strength of 280 kilos. Thats too weak. Tube tape is stronger. 4. I would tied the two trees off seprately, just in case one goes. Pad the trees. 5. The edge the cordelette is resting on, is not protected. 6. The rock doesnt seem to be of the best quality, judging by the small stones imbedded in it. I would'nt expect too much from this set-up. Sorry man. The whole system would be a bit better if 11mill static line where used. It will be far stronger, and it takes less time to rig.
:lol: :lol:
Anchor Nazi indeed. :wink:
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hippie_dreams
Jun 13, 2004, 2:17 PM
Post #62 of 70
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I really appreciate these posts. It gives those of us who are newbie's with anchors some experience with what not do. Thanks guys and gals!
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grayzed
Jun 13, 2004, 3:06 PM
Post #64 of 70
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personnally i think the anchor is fine the knot has a pretty long tail and is unlikely to come undone. the tree is relatively safe from damage unless it gets used over and over. but as long as nothing is pulling across the tree I cant see much harm done.
:D
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grayzed
Jun 13, 2004, 3:10 PM
Post #65 of 70
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all though i probably would have set it up differently but I definately have to be honest I would have used the tree.
again I wouldnt of hurt the tree..
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ben87
Jun 13, 2004, 5:26 PM
Post #66 of 70
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"It is hard to see the cam placements or to know if the plates can be trusted, but whoever said that the black cam is too small to trust is a bit off. Maybe you meant a different brand (alien??), but that looks like a black metolius to me and if so is the size of a 3/4 camalot. The small metolius cams are grey and purple."
I'm the one who said this, and you're right -- I was thinking of the black alien. -ben
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knudenoggin
Jun 16, 2004, 3:58 PM
Post #67 of 70
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In reply to: In reply to: you can't tell what knot it is...what, an overhand? Correct - overhand knot, with no backup. Should have been a grapevine; overhand knots like that - silimar to an EDK - have a tendency to roll unless backed up tight to the first knot. T
No, it's not an Offset Overhand: it's a an Offset Fig.8, but in an unusual
*stopper* orientation. Positioned as it is around the 'biners, it's okay;
I'm not sure how vulnerable it is to being moved from that position, though.
As for needing a back-up, no, the EDK properly tied should not, for abseil
(where loads are minimal). Here, the issue was adjusting the length of the
long runner to the trees, and I think that the way to do this was to form a
long runner (grapevine or Fit.8 (NOT Offset!) or Ashley's Bend), and to tie
a Bowline to get the adjustment. Or hitch the runner around the tree
(ignoring, yes, the entire argument against tree use--not a knotting point)
with a Munter (end bight of runner around itself) finished/secured with Two
Half Hitches, 'biner clipped end. Actually, this hitch would be better set on
the 'biners, which is where the user can best make the length adjustment
also.
--knudenoggin
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shakylegs
Jun 16, 2004, 4:43 PM
Post #68 of 70
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In reply to: 6. The rock doesnt seem to be of the best quality, judging by the small stones imbedded in it.
Um, it's called quartzite conglomerate.
Besides that, most of what you said was spot on. However, I use 5mm myself, and have never worried about it.
But, as someone mentioned above, the #1 cam looks shallow.
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knudenoggin
Jun 23, 2004, 10:05 PM
Post #69 of 70
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In reply to: 3. The tree is girth hitched. This will reduce the strength of the cord up to 50%. The knot will reduce the strength a further 30%. There is a knot resting on the biners. You are using 6 mill cord. It's too weak for a TR set-up. 6mill cord has a breaking strength of 800 kilos. Minus the 30% for the knot equals 560 kilos. Now there is a breaking strength of 560kilos left. Minus 50% for the girth hitch equals a breaking strength of 280 kilos. Thats too weak. Tube tape is stronger. ... The whole system would be a bit better if 11mill static line where used. It will be far stronger, and it takes less time to rig.
You don't add the weaknesses of parts of the system to some total: rather, the weakest link
determines the limit. The Girth Hitch would be stronger were the loaded lines led around the tree in a
straight line, rather than pulling so much on the end bight. The strength of the Fig.8 Stopper knot positioned
at the 'biner pair is unknown to me--never seen strengths for stoppers--, but 30% is probably optimistic.
Using your figure of 800k for 6mm, you double that for the paired-rope runner ( = 1600k),
then reduce it by whichever weakness is greatest (let's take 50% as a tie: = 800k).
As for making the anchor with "stronger" material, you might be better off with dynamic stuff,
if doubling it in cordelette arms & runners, esp. over short spans.
--knudenoggin
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climbfrog
Jun 26, 2004, 11:45 PM
Post #70 of 70
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Why would you double 800k for a paired rope runner knude? What happens if a single strand breaks anyhere in that cord? I still think each tree should have been tied off seperately, and with something way beefier than that 6mm cord. And tied off perferrably with something besides a girth hitch.
I am learning from this too by the way.
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