The story behind this is that for weeks, I had been looking for a way to tie up a belay anchor to a tree. I needed something that would be snug to prevent slipping up and down the tree as tension changed and not keep tightening around the tree as tension increased. I first looked at the Girth Hitch. This tightened up to the tree but if tension wasn't maintained, it loosened up and slid up and down the tree. It also got tighter and tighter as tension increased. The other knot I looked at was the No Knot. This is where you just wrap three times around the tree and then tie a water knot to connect the ends. This was better on the tree, but still didn't stay snug when not weighted. I decided to see if I could come up with my own knot to do what I needed. That is when I randomly came up with what I am calling, Ammon's Clef Knot (because it looks like a clef note when tying). It is basically a locking slip knot. If someone else has already come up with this knot, then great they can have the credit, but they really should publicize better because I couldn't find it. Now, before I show you how to tie it, I should tell you that I have not tested it and I have no idea if this affects the strength of the cord or webbing. I'm sure there are some experts out there that could help with this, but that is not me.
Step 1. Start with one end of the rope:
Step 2: Cross the end over the line.
Step 3: Loop the end around the line, back on itself or toward the loop.
Step 4: Loop the end again around the line further up toward the loop.
Step 5: Pull the end down through the first small loop created in step 3. (this is where it looks like a clef note)
Step 6: Pull tight by pulling the end and the diagonal side of the loop.
As the ends of the cord or webbing are pulled, it pulls the knot tighter, keeping it from sliding. To use this in your belay, anchor to a tree do the following:
1. Wrap around the tree three times
2. Tie Ammon's Clef Knot and tighten it to the tree to the desired tension
3. Join the ends together using a Water Knot
At this point, you can clip into the anchor. Ammon's Clef Knot will keep the three wraps from slipping up or down the tree as tension varies. If tightened correctly, it should not tighten any more or less around the tree. The three wraps spread the weight out on the tree preventing damage. The knot doesn't cause any sharp angles so I would think the strength of the cord or webbing is not compromised.