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tradman
Jun 10, 2005, 9:11 AM
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Okay, here's a rigging question for all you anchor experts.
You're climbing at a single-pitch crag, and some members of your group want to top rope a few lines to get their confidence going.
When you get to the top of the crag, there's only one thing to anchor to - a huge boulder, about 10 meters back from the lip. It's easily five feet high and about 20 feet round, so there's no chance of getting a sling around it.
You do however have a spare 60m rope, and as many other bits and pieces as you want, although there are no placements on the boulder. Running the live rope all the way to the boulder results in heinous rope drag anyway.
So here's the question: how would you go about building a top rope from that boulder? Or would you?
Last word: I actually did this at the weekend, I'm simply interested to see what solutions folks come up with.
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erclimb
Jun 10, 2005, 11:41 AM
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I would never use a dynamic line for a toprope anchor...even if there were great placements or the possibility of tying off around the boulder. The dynamic quality of the rope would cause the rope to saw back and forth over the edge of the crag; in your suggested scenario of slinging the rope around the boulder, you would risk damage at several points on the rope.
Of course, I would want my friends to climb; so, I would tie a bowline around the boulder, extend the line to the edge (at maximum stretch), clip in, and give a top belay.
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thetroutscout
Jun 10, 2005, 11:47 AM
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I would but I carry enough webbing (usually) for such situations. I'm guessing you used the rope in some way. So your anchor would have some dynamic properties to it, especially over a longer distance. So remember to protect the anchor rope from the edge so you don't tear up your sheath.
^^ike
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cfnubbler
Jun 10, 2005, 1:28 PM
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Exactly as I would with a static line off of any other beyond question single point anchor (BFT with intact root system, ect.):
2 independent strands secured around the anchor with knots of your choice- bowline, eight, friction wrap, whatever, brought to a redundant power point, positioned to minimize drag and wear on the belay line, and well padded at all potential friction points to minimize abuse of the anchor rope.
I'd also check it fairly frequently to make surfe the dynamic anchor line hasn't shifted off of the padding.
If unable to pad the anchor line sufficiently, I'd arrange a top belay so I could monitor things closely.
-Nubbler
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landgolier
Jun 10, 2005, 1:36 PM
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Top belay and tell the punks they don't get to hangdog.
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paulraphael
Jun 10, 2005, 7:15 PM
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I'm with Nubbler. If you wrapped that boulder twice like a big cordelette (cordelissimo?) you'd have 4 strands of dynamic rope taking the load. having the load shared by 4 strands over such a short distance will barely be dynamic at all.
If you take all the usual precautions (make sure none of the strands are loaded over edges, etc.) it should work perfectly.
If it's a rope that plan to lead on, I would be exra careful with it, and would definitely inspect it for abrasion afterwards. But I'd sooner rig an anchor like this with a lead rope than use one for the toprope itself.
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bluenose
Jun 10, 2005, 7:52 PM
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Noob checking in here, so take this with much salt...
I was buying stuff for my planned TRing. One of the first things was a loooonnnggg piece of 6mm static cord. I figured if the slings weren't long enough I could always fashion something with it. I'd just do a double wrap around the boulder, eight on a bight and clip in for a top belay. Without that, do the same with the climbing rope, maybe another go around or two and bring the power point out close to the edge, clip in and top belay. No nasty edge drag this way.
Noob checking out here.
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paulraphael
Jun 11, 2005, 4:40 AM
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Noob, you're describing making a big cordelette. It would work fine, but in the interests of strength and durability I'd suggest going to 7mm. Especially since you're only talking about two loops around the thing.
One thing to keep in mind is that static cord isn't really static ... it's just less dynamic than climbing rope at a given size. But cord as small as 6mm stretches a lot. I have a pair of rock rings hanging from about 3 feet of 6mm, and i feel it stretching noticeably under half my body weight. 7mm is significantly more robust for what you're talking about.
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bluenose
Jun 11, 2005, 4:29 PM
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Well, I haven't tried weighting it yet so I'll play with it before actually using it. 7mm sounds more comfortable anyway.
Tradman hasn't checked back in to tell what he did though.
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mcfoley
Jun 11, 2005, 5:55 PM
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I would have used a static line or webbing, however, it sounds like you were creative with your anchor building, which is an asset!!!
You never know what you will end up with when building anchors...marginal placements, lack of gear, etc...this dicatates that we all THINK when we are presented with a situation like you were in...Achor building rules apply nor mater what, however there are so many ways to rig...
A lot of people starting out learn the basics of building anchors and try to apply the same identical anchor they were taught, to all situations...leaving them with sketchy anchors... I'm not talking about you per say, but this is pretty common...
Questions for you...
There were no gear placements at the BASE of the boulder???
Was it fused the the rock formation, bad rock, or did you not have any gear?
Could you have built an anchor at the top of the route (before topping out)?
Did you lead it?
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tradman
Jun 13, 2005, 10:36 AM
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Thanks for all the answers!
We did pretty much exactly what nubbler described (thanks mate) - 2 independent strands equalized to one point, protected from abrasion with carry mats. Worked just fine, and a decent solution in light of the fact that the crag is remote enough to require us to camp out overnight at it.
Oh and by the way, do some of you seriously carry upwards of 20 metres of 7mm cord with you when you go cragging? Wow!
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jammer
Jun 13, 2005, 12:27 PM
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I have two 10.5 X 30 meter long static ropes just for this purpose. Don't worry about the weight, it'll build your leg strength as you lug it around. I'd never use a dynamic rope for an anchor (unless it was an emergency, then anything that works goes).
hj
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fallingup
Jun 13, 2005, 1:19 PM
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Since we are on the subject of top-rope anchors, here is another question. I have 30' of 8mm static line and 22' of 1" webbing. If the anchors are far apart, would mixing the 2 different types of cord result in an issue? Assuming of course that they are equalized and have the proper redundancy.
Thanks for the input.
fallingup
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billcoe_
Jun 13, 2005, 7:25 PM
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In reply to: Since we are on the subject of top-rope anchors, here is another question. I have 30' of 8mm static line and 22' of 1" webbing. If the anchors are far apart, would mixing the 2 different types of cord result in an issue? Assuming of course that they are equalized and have the proper redundancy. Thanks for the input. fallingup
Issue: ?
No.
thats my opinion of course, never used those materials together before. You're putting body weight on some high strength items, as long as they are not over a sharp edge, why not?
Bill
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stone_glswrx
Jun 14, 2005, 7:25 PM
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tgreene
Jun 14, 2005, 8:01 PM
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I have a custom made 40' 7/16th sewn sling for such things, so there aren't many situations that I can't handle. I guess if I ever actually needed more, then I could always cut it and use the full 80'... 8^)
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shiggetyshiva
Jun 14, 2005, 8:18 PM
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fallingup,
Mixing static line with webbing on a TR setup *shouldn't* be a problem, provided you've got everything equalized and redundant. Static line stretches only a very small amount (i believe it's like 2%), so for a well-belayed TR "fall" this difference vs. the webbing shouldn't be an issue.
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