So you are out hiking with some buddies, you are looking for the top of a climb or rappel but just can’t seem to find it. You dragged all your gear with you, and really want to get a good run in. So you solve the problem by using a tree as a natural anchor. Easy enough. But is the tree strong enough to hold your body weight as your rappel down? Or will you pull up the roots hand have the whole tree come down on top of you? This is your guide on how to rappel down a tree, as in using a tree as a natural anchor.
There are three things to ask yourself before rigging a tree to rappel down. Is the tree alive, what is the diameter of the tree, and what is the tree’s environment like. If the tree can pass the test, it is safe to use. (If you just want to know how to rig an anchor to rappel down a tree, skip down to the subheading, “How to Rig an Anchor and Rappel down a Tree.” But I’d at least glance over picking a safe tree to rappel down.
Is the Tree Alive?
This one should be a no-brainier. Do not rappel down a tree that is dead. The tree is dry and old and could snap under pressure, sending you down with the tree on top of you. Double whammy. So this may also seem like a no-brainer, but lets talk a little about how to tell if a tree is alive or dead. Obviously if the tree has lush leaves growing on it, it is alive. Look for leaves that are wilting. Wilting leaves are a sign of stress in the tree. Leaves are a good indicator of the overall health of a tree. Obviously, be sure the leaves are the right color for the season. The leaves should not be wilted or have excessive insect damage. There should not be oozing sap. These are sure signs the tree is unhealthy and unstable to rappel down.
But perhaps it is early spring or late fall and it is a little hard to tell which trees are healthy and which ones are dead.
- Check the bark. With the exception of some birch trees, maples, and eucalyptus tress, the bark should not peel.
- Check for fungi growing on the trunk. (Moss is not a fungus.) Fungi is a sign of instability and poor tree health.
- Check for signs of insects. All trees and plants are going to have some bugs on them. But excessive bugs is a sign that the tree is dead. Check for holes in the bark, branches, and leaves. If there are holes all over, move on to the next tree.
What is the Diameter of the Tree’s Trunk?
I’ve heard people using a the rule of thumb, “five and alive.” Meaning the tree’s trunk must have a five inch diameter and be alive in order for the tree to be safe to rappel down. Let’s think about this. Are you going to trust a baby tree with your life? I’ve even seen webbing left behind on a three inch tree. Nope. Not me. I like to look for a big thick, healthy tree. A tree that has a trunk at least 10 inches in diameter. Remember, to find the diameter, you must divide the circumference by 3.14 (pi). So always carry a measuring tape and a calculator. No, I’m kidding. Even I am not that crazy. Just eyeball it. Here are a couple of ways to help you eyeball.
- The “thigh” rule. If the tree trunk is the diameter of your thigh, then its thick enough to rappel down. I have no idea what the average diameter of a thigh is, but it seems like a so.
- Another test I like is the foot test. Is the base of the tree trunk trunk as long as your foot? If it is, then its safe. Now if you have particularly large feet, then obviously the tree can be a little smaller.
- And one last way to help you eyeball, the diameter of the tree should be about the same as your helmet.
If the tree looks healthy and has a think trunk, I do the lean test. Lean up against the tree trunk with your back and put some pressure on it. Does the trunk budge or bend? If you are stronger than the tree, don’t use it. Always look for big healthy trees.
What is the tree environment like?
Here is the last question to ask yourself before you rappel down a tree. Why would the environment matter, you ask. There a couple of reasons. The environment determines root system, and root system can determine strength. Trees in wetter climates like the Pacific Northwest, or the East Coast have a wetter, more humid climate. The roots don’t have to dig for water, and can stay at the surface, making the tree much easier to pull up or blow over. Rappelling down a tree with a thin trunk in a wet climate can be a recipe for disaster. Trees in drier climates are much more reliable.
The wind also plays a factor in a trees root system and strength. I once read a paper, giving trees kN ratings, based off wind loading. The paper can be summed up by saying, a tree that is exposed to more wind has a stronger kN rating. It concludes by saying if the tree is only exposed to light winds, use a tree that is helmet sized or larger. If you are in an area with high seasonal winds, and exposed to wind storms greater than 45 miles per hour, the tree has a higher kN rating, so even smaller trees can be used as anchors.
Always, before your rappel down a tree, use your best judgement. I can talk all day long about which trees are safe to rappel down and which ones are not, but the fact of the matter is, you have to do what you feel is safe. Never do something risky. Its just not worth it. If you’re not sure, just don’t do it. If you think a tree looks strong and can hold you on your rappel, then by all means, go for it, rig an anchor and rappel down a tree.
How to Rig an Anchor and Rappel down a Tree
Now that we have painstakingly picked just the right tree to rappel down, lets talk about HOW to rig an anchor to a tree to rappel down. There are a few ways.
- If you are doing a fairly simple rappel, and you’ll be going back to retrieve your rope, you can do a pretty simple anchor. Tie your rope, around the base of the tree trunk, using a figure-8
follow throughknot, leaving about a three inchtail. Click here to read our article on knots,if you need instructions.
- A very common rig: Use three
seperate1-inch nylon webbing slings. Tie each sling with a water knot around the tree, threaded with two rappellingrings. Thread your rope through the rings.
- Use a
48 inchnylon sling and double it up tied with an overhand knot. Hook up your locking carabiner and lock it into your rope.
- Use a
cordeletteand tie the ends together with a double fisherman’s knot to create a large loop. Double up the cordeletteand wrap it around the tree. Tie a figure 8 loop and clip in your carabiner.
- Now if you need something stronger and will be ascending the rope, start your anchor by wrapping one end of the rope, several times around the tree, about five times should do the trick, and tied with a figure eight loop that is clipped to the load strand of the rope with a locking carabiner. This is the strongest and most preferred way to rappel down a
tree,or rig a tree anchor, as the figure 8 loop knot is not exposed to any pressure. All the pressure is on the tree.
As always, use your best judgement and don’t do anything I wouldn’t do. Enjoy your rappel. If you plan to rappel down a tree, you’re probably enjoying nature and life to it’s fullest. Remember to always check your knots and your gear before you back off the edge. Happy rappelling!