SRT rope tied off at natural anchor (tree)

[stephen]

Does anyone have an opinion regarding suitable tie offs for a SRT rope to a natural anchor (tree)? Any problems with a double bowline? Any better alternatives? Thanks.

[Scott McCrea]

A double bowline would work, but there are better, easier, safer and stronger options. By far the most common way to anchor to a tree is with a tensionless hitch. Simply tie a small loop at the end of the rope with a figure 8 on a bight and wrap the end around the tree a few times. Put a locking biner in the loop and clip it back into the rope. Here's some pics:



Here's an animated depiction of the tensionless hitch: LINK

On Rope, suggests that you should only use two wraps with the tensionless hitch and make sure the biner is snugged up to the rope, so the torquing/twisting forces are lessened.

[Tim White]

Click to see larger image.

My preferred method is a tensionless hitch (high strength tie-off). The knot never sees a load, thus maintaining the full strength of the rope.

Please note the NCRC Copyright of this image. Used here for your benefit.

[Scott McCrea]

Thanks Tim, that's a better picture. It shows the two wrap technique and padding wrapped around the tree under the rope to protect the tree.

[Tim White]

There you go again, Scott! :kidding:
You won this time...got you reply up before I did.

[Dwight Livingston]

It seems a 'biner is commonly used in the tensionless hitch, and the examples above all show it. But why the 'biner? Do you leave the figure eight knot in place during storage? Is it in anyway functionally different from tying directly to the main line? Nothing wrong with using a 'biner that I can think of, though I always feel a 'biner is more of a temptation for theft that just a rope. Anyway, I usually just tie to the main line.

Dwight

[Scott McCrea]

...why the 'biner? Do you leave the figure eight knot in place during storage? Is it in anyway functionally different from tying directly to the main line?

You're right. The biner is not necessary. The only real benefit to the biner I can think of is if you want to lower someone with the wraps. It's faster to unclip the biner and clip it to another rope than it is to untie the knot and retie it to another rope.

The other potential issue is the nylon rubbing on nylon thing. I don't think it's a big deal but some don't like it. Using a biner eliminates this issue.

If my rope is in a bag, I leave a fig 8 on a bight on each end. If it's coiled, no knot.

[Tim White]

It seems a 'biner is commonly used in the tensionless hitch, and the examples above all show it. But why the 'biner? Do you leave the figure eight knot in place during storage? Is it in anyway functionally different from tying directly to the main line? Nothing wrong with using a 'biner that I can think of, though I always feel a 'biner is more of a temptation for theft that just a rope. Anyway, I usually just tie to the main line.

Dwight

OK, Dwight you caught me. That is the "official" NCRC / On Rope method. It is not exactly the method I use.
OK, so I admit it... I did say that it was “My preferred method...â€

[Dwight Livingston]

Scott and Tim

Thanks for the replies. I'm glad to know there's no gotcha I wasn't aware of.

Dwight

[GypsumWolf]

Most of the time I forgo the biner and tie a follow thru fig. 8 around the standing line.

So... the nylon on nylon this is ok in this situation? I guess so, because the rope is not rubbing much.

I always have used the carabiner. I probably will do it that way forever.

[mabercrombie]

If you wrap the tree right no weight will ever be put on the knot, it is all distributed through the wraps.

[cavemanjonny]

What about when the tree is really close to the edge of the pit? In the above examples, the standing end of the rope is nearly perpendicular to the tree. What about when the tree is near the edge of the pit such that it drops directly down, nearly parallel to the tree, such as in the nice little picture I drew .

Assuming the tree is stable, what is the best way to rig it, I've found that the rope nearly always pulls against the biner in this configuration. Should you use a wrap-3-pull-2 instead?


[/img]

[hank moon]

What about when the tree is really close to the edge of the pit?

In a recreational caving situation, there is no advantage to using a tensionless tie-off. It's easier to pass the rope once around the tree and tie it off using a bowline or other suitable knot. For frequently-used trees, padding should be used to prolong its life.

[RescueMan]

Thanks Tim, that's a better picture. It shows the two wrap technique and padding wrapped around the tree under the rope to protect the tree.

Actually, I wouldn't consider either of Tim's NCRC versions a tensionless hitch since with just two wraps on a rope pad there would not likely be sufficient friction to keep tension off the knot.

It is the bark of the tree which offers the high level of friction. If the hitch doesn't spin on the tree, it should not harm the bark and should not require padding.

On Rope suggests that you should only use two wraps with the tensionless hitch and make sure the biner is snugged up to the rope, so the torquing/twisting forces are lessened.

To avoid the torque on the tree would require that some of the load be shared by the knot, which makes this anchor a two-wrap girth hitch.

So... the nylon on nylon this is ok in this situation?

There is no rule prohibiting either nylon-on-nylon or metal-on-metal, just some obvious caveats about both. With linked metal, watch out for torquing. Nylon moving against fixed nylon will melt the fixed nylon. If there's either little movement (such as this tie-off) or both rub points are shifting (such as a Munter hitch), there is no problem.

What about when the tree is really close to the edge of the pit?

The danger in your drawing is shallow (possibly exposed or cut) roots and a high attachment point which can lever the tree right out of the ground. Though the rappel start is trickier, I'd generally keep the anchor low on the tree unless it's a bomber tree.

Otherwise, I agree with Hank - KISS (keep it simple and safe). Use a simple bowline, backed up with a double overhand or Yosemite finish.

- Robert

[cavemanjonny]

The danger in your drawing is shallow (possibly exposed or cut) roots and a high attachment point which can lever the tree right out of the ground. Though the rappel start is trickier, I'd generally keep the anchor low on the tree unless it's a bomber tree.

Right, that's why I said I was going to assume the tree was stable, to simplify things.

I'm most curious as to how you would rig the tree, assuming you are constrained to using it. If you rigged extremely low, you would still have the problem of the rope pulling down against the biner (or knot), and you wouldn't be able to get on rope without using a pigtail, which would complicate the rigging that much more.

Again, my question is, assuming the tree is bomber, is it possible to rig it using a tensionless wrap while preventing the rope from weighting the biner (or knot).