SRT rope tied off at natural anchor (tree)

[killian]

I use more of a top rope rock climber set up with webbing and to locking beaners. Is this an no no or acceptable? because i prefer more tie off points then just one but that may be because i use the three or more rule for top rope climbing.

[RescueMan]

I use more of a top rope rock climber set up with webbing and to locking beaners... because i prefer more tie off points then just one but that may be because i use the three or more rule for top rope climbing.

When you say "tie-off points" do you mean independent anchors? Is that what you mean by the "three or more rule"?

If so, then I'm afraid to say that there is no such "rule". A top-rope anchor, like a belay station anchor on lead or a rappel anchor, merely has to be "bomb-proof".

If there is one 12" diameter live well-rooted tree, then that is certainly sufficient for any anchor - recreational or rescue. If you're using artificial pro, particularly in questionable cracks, then three load-sharing anchors are advisable. I've rappeled from multiple bushes clove-hitched together when that was the only available anchor.

The only "rule" is that the anchor has to be safe and reliable.

In that light, if one wants to rig high on a tree near the lip, a way to secure the anchor is with a pre-tensioned backtie, using a non-moving 3:1 MA with a prusik PCD, or a trucker's hitch, and interlaced W3P2 webbing anchors at the high directional.

- Robert

[Stridergdm]

I use more of a top rope rock climber set up with webbing and to locking beaners. Is this an no no or acceptable? because i prefer more tie off points then just one but that may be because i use the three or more rule for top rope climbing.

Is it safe?

Does it work?

Ok, obviously you know #2, since it works for you.

#1... well depends. In some cases it's the ONLY way to rig. A tensionless rig sometimes works great. Sometimes there's no single point that's appropriate.

So it depends. But I'd hazard against over complicating it. For one thing it's more things to fail. For another, it can take longer to setup, when your goal is to cave! And finally it's extra gear to carry.

So is it what you do wrong? Nope, not necessarily.

[chh]

In that light, if one wants to rig high on a tree near the lip, a way to secure the anchor is with a pre-tensioned backtie, using a non-moving 3:1 MA with a prusik PCD, or a trucker's hitch, and interlaced W3P2 webbing anchors at the high directional.

Other than in rescue applications, why on earth would you want to pretension the rope between the anchor and the directional? Seems like a lot of work to me. Rope goes from the directional to the bomber anchor. Or if the tree at the lip is good enough, wrap it and go. Your directional is only going to be as high as you can reach anyway. KISS.

[RescueMan]

Other than in rescue applications, why on earth would you want to pretension the rope between the anchor and the directional? Seems like a lot of work to me.

The KISS principle is what I live by - but it stands for Keep It Simple & Safe.

Trees near or at the lip of a well-used pit or cliff are typically questionable as anchors. The soil is shallow, what soil is there has been thoroughly compacted by use, the roots are limited in depth and spread by the proximity of the ledge, the tree is often half dead.

I've seen such commonly-used anchor trees suddenly uproot. And attaching a rappel line "only as far as you can reach" creates sufficient leverage to achieve this, particularly if you add the torsional stress from a "tensionless" anchor.

A slack "back-up" anchor is no back-up if a primary high anchor point is questionable. In such a case, a pre-tensioned back-tie (if a suitable bombproof anchor is available) not only provides a safe anchor but also changes the load vector at the high directional to something closer to vertical or backwards (rather than forwards over the edge).

Sure, if you have enough rope to simply sling it over a branch of the directional tree and tie it off to the closest bombproof tree, that will perform nearly as well.

- Robert

[Anonymous_Coward]

Other than in rescue applications, why on earth would you want to pretension the rope between the anchor and the directional? Seems like a lot of work to me.

If the backup is not pretensioned, then it is of no use at all. Even if the anchor holds, the shock load could could kill you.

[chh]

Trees near or at the lip of a well-used pit or cliff are typically questionable as anchors. The soil is shallow, what soil is there has been thoroughly compacted by use, the roots are limited in depth and spread by the proximity of the ledge, the tree is often half dead.

I've seen such commonly-used anchor trees suddenly uproot. And attaching a rappel line "only as far as you can reach" creates sufficient leverage to achieve this, particularly if you add the torsional stress from a "tensionless" anchor.

A slack "back-up" anchor is no back-up if a primary high anchor point is questionable. In such a case, a pre-tensioned back-tie (if a suitable bombproof anchor is available) not only provides a safe anchor but also changes the load vector at the high directional to something closer to vertical or backwards (rather than forwards over the edge).

Sure, if you have enough rope to simply sling it over a branch of the directional tree and tie it off to the closest bombproof tree, that will perform nearly as well.

I'm not advocating for slack in the system. I was picturing a redirect scenario. However, I see your point about changing the vector forces on the primary anchor (i.e. the one closest to the drop) with a pre-tensioned back up anchor. This would potentially stabalize an anchor that wanted to fail in a particular direction, like a tree that wants to fall in the hole. However, if you are using a trucker's hitch you already have more than enough rope to just use what is to be your back-tie and then run the rope through a directional at the "questionable" primary anchor, performing nearly as well as a tensioned back-tie and taking far less time and fidgetry. Also, in this case I'd think there would have to be a pretty good reason as to why you are using the directional in the first place and just making it easier to get on rope I don't think necessarily counts. Now, if you were making the back tie with additional materials (other than the rope) and had a prussik progress capture system I wonder if you couldnt just extend the "backup" anchor closer to the drop with all of that stuff or explore some other option. It seems to me that with what you would have to carry to create a pretensioned back up, or the extra rope you would have to use in the MA system you could just walk a little further back and find a bomb proof primary anchor, (i.e. tree - sticking with the original focus of the thread.) Either you've got the rope to do the drop or you don't...

Now, if you were WAY back there and it was impossible to make a straight line with the line connecting the primary anchor and the back-tie, I could see using a MA or truckers hitch (or all of your burly caving buddies) to take as much slack out of the system as possible.

It is possible that I'm still not picturing your back tie well enough though, and the relative distances (both horizontally and vertically) between the two anchors that you have in your mind as a theoretical scenario. Varying these would change the equation a little. But then you get into specifics and "it depends"

[Vertigo]

What about trees that are way too big to fall into the pit? In other words, if the tree fell, it would fall across the pit?

[Scott McCrea]

What about trees that are way too big to fall into the pit? In other words, if the tree fell, it would fall across the pit?

If you survive the shock load and falling debris, then you just have hope the big tree didn't completely cover the entrance trapping you in the cave. Or you could just go ahead and cut it down so you can rig right in the center of the pit.

[chh]

What about trees that are way too big to fall into the pit? In other words, if the tree fell, it would fall across the pit?

....and if nobody is there to hear it, does it make a sound?







sorry, couldn't resist

[RescueMan]

I'd think there would have to be a pretty good reason as to why you are using the directional in the first place and just making it easier to get on rope I don't think necessarily counts.

Making it easier to get on and - more importantly - easier to get back up over the edge is the best possible reason for a high directional. Edge trauma is messy and dangerous, and navigating the lip on ascent can be difficult and ugly.

Now, if you were making the back tie with additional materials (other than the rope) and had a prussik progress capture system I wonder if you couldnt just extend the "backup" anchor closer to the drop with all of that stuff or explore some other option.

You could, but long anchors tend to be messy, may involve rub points and mud, and even with webbing add some stretch to the system.

I use 8mm cord for back-ties (since there are 3 strands to share the load) and webbing for Wrap-3-Pull-2 anchors, which offer strength, cinching, and allow direction changes better than almost any other anchor system. Carrying some webbing and 8mm cord to the pitch head is usually easier than carrying extra 11mm rope.

Now, if you were WAY back there and it was impossible to make a straight line with the line connecting the primary anchor and the back-tie...

If you can't find an in-line secondary anchor, then it's sometimes possible to vector two back-ties to create a focused or floating anchor point where it's needed. Taking a little extra time and effort to build the primary anchor for entering and leaving a pit doesn't seem to me to be excessive, since that's your lifeline back to the world and may see 2-person loads if a pick-off is needed when the party is exhausted on ascent.

It is possible that I'm still not picturing your back tie well enough though

I've tried several times to upload an image without success, even though my files meet the requirements of PostImage.org