Question:
Hi Yann,
Can you help with any advice regarding the right tree? I’m worried about putting the rope too high, as the moment force on the tree will increase. But if I go too low, I’m concerned it could slip up.
Thanks!
My Answer:
Hi Mate!
Your judgment is key here—but it should be an informed one. Here’s a step-by-step guide to help you experiment and find the safest setup:
- Attach Your Rope or Slings:
- Use a couple of wraps around the tree to create friction, similar to how a Prusik works. A clove hitch can be a good option. (see video 1 and 2 for reference)
- Secure the rope with a strong knot, like a double figure-eight on a locking carabiner or a bowline with a backup.
- Start Low:
- Attach the rope where you feel it might be “too low.”
- Rig the rest of your setup, ensuring everything is secure.
- Test the System:
- Safely load the system by putting your weight on it with your feet slightly off the ground.
- Observe whether the knot or wraps on the tree move.
- Adjust and Improve:
- Based on your observations, tweak the setup.
- Add more wraps if needed—especially for slick-bark trees where more friction is necessary.
For better friction, aim for something similar to a Chinese finger trap (see video 3 for reference) effect or the grip of a VT Prusik (see video 4 for reference). A few iterations should lead to a safe and reliable setup.
General Guidelines for Tree Anchors:
- Tree Diameter:
- Minimum 6 inches in diameter.
- Tree Health:
- Ensure the tree is alive and has a healthy, strong root system.
- Attachment Height and Strength:
- Load the tree as low as possible to reduce leverage.
- Remember these approximate strength guidelines:
- 6-inch diameter: Safe when rigged properly.
- 8.5-inch diameter: Twice as strong (allows for higher attachment).
- 12-inch diameter: Four times as strong.
- 14.5-inch diameter: Six times as strong.
- 17-inch diameter: Eight times as strong.
Experimentation and caution are your best tools. Test thoroughly and adapt based on what feels safe for your specific location and conditions.
Anything else you’d like to ask?
Additional Insights from Sebastiaan Verbeke:
After reading this article, Sebastiaan Verbeke shared some fantastic points that can further improve the safety and reliability of tree anchors. Here are his thoughts:
- Load Direction: Consider how the tree will be loaded—in shear or at an angle. Attaching lower on the tree reduces the angle between the tree and the rock, leading to more shear loading and less leverage.
- Sliding Prevention: Position the attachment point below a groove or branch stub to prevent sliding.
- Rope Position: Avoid setups where a fall might cause the rope to cross between the tree and the rock. (If there is a pinch point)
- Impact Force: Lower attachment points increase the amount of rope in the system, reducing impact force.
- Tree Species and Root System: While species isn’t critical, prioritize trees with thick trunks and strong, deep root systems. Be cautious if the tree is on thin, sandy soil or shallow bedrock.
- Knots:
- Sebastiaan recommends avoiding the double figure-eight for this purpose, as it requires pre-measuring the rope length.
- For LRS anchors, he suggests avoiding bowlines or double figure-eights. These can interfere with friction knot tightening.
- His preferred knot: the clove hitch. It’s simple, effective, and minimizes rope usage.
- Tree and Rope Protection: Always use protection to safeguard both the bark and the rope. Be mindful of potential slippage.
Acknowledgment:
Making the climbing community safer is a task we tackle as a group. Huge thanks to Sebastiaan for sharing these excellent ideas, which make the article richer and more comprehensive. Together, we make climbing safer for everyone!
Great examples (one clove, one with just 2 loops, see from 1min to 8min) shown by Joshua Perry and Yann
Example of a friction knot on tree. Be sure to finish it with a more secure knot at the end!
Chinese Finger Trap:
VT Tresse Friction Knot: