Industrial spansets are the best tools to make a highline equalization. Particularly, for a treeline, or for a highline set up on trees next to a cliff, the anchor is easy to set as you only have to circle the tree with the spanset.
Sometimes though, it happens that we face an adjustment of the spanset – even on the ground – . Too short, you of course add an other spanset. Too, long you need to adjust it.
When the tree’s circumference is smaller than the length of your spanset, the spanset resistance is huge (upper picture) – as the spanset resistance is doubled -, but once you let this anchor with no tension, the spanset is always moving down along the tree. This situation is tiresome when you are trying to rig a treeline alone, as you will have to climb multiple times to the anchors to adjust everything.
The cow hitch on a tree is a very good solution, as the cow hitch maintains the spanset where you set it. The spanset resistance is 80% from its nominal resistance, which is enough considering the safety factor on such spansets. But in this case (lower picture), the remaining spanset length pushes back the webbing from the tree, meaning that the highliner will need to walk on the spanset to reach the tree and the leash may stop too early. A knot on the spanset is of course possible to reduce the length, but would be really hard to untie.
If the tree is small enough, it may be possible to make an extra tour with the spanset before doing the cow hitch, but in some case you will be on this situation : too long in double, too long in cow hitch, too short for an extra tour.
The “adjustable” knot
Take a 2m spanset. It can circle a 2m large tree. Doubled it can circle a 1m large tree. In between 1m and 2m, the adjustable knot is here to adjust your spanset without making a real knot.
Stages 1-2-3
It is simply a “fake” knot on the spanset. At the bottom, you see the spanset doubled. This will absorbe the sling’s extra-length.
Stages 4-5
While sliding up and down the “fake” knot, you can adjust the length. The higher is the knot, the shorter the sling here. It is important to equalize the 2 strands so that the knot works correctly.
Stage 6
Once adjusted, making a cow hitch will have the same advantage than a classical one : the spanset will not slide.
Conclusion
No knots has been done on the sling, it will not be difficult to uninstall. Even though we don’t know the resistance of this knot on a spanset, it seems reasonable to think that it has almost the same resistance than a cow hitch. As an example, on a 2T spanset, there will be a 1,6T working load limit and a 8T breaking load limit, which is barely enough for a highline and even a longline.
We showed this knot in action on a tree to circle, but of course there can be many other ways of using this knot when a spanset is too long. Use it where you want.
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