Before we start this..
Highlining is potentially dangerous. Learning about highlining on the internet is definitely stupid. The methods and equipment shown here are highly experimental. Only do this at home!
Today, I will discuss a hypothetical option for building a highline main anchor purely out of dyneema. The anchor shown is equalizing, non-extending, adjustable and redundant. It’s also easy and quick to install and works in a variety of different situations. Let’s take a quick look:
As you can see in the video, the anchor is based on 2 connection points. Whether that is 2 bolts, boulders, trees or whatever. As long as you can install a metal connector on it, you can use it with this method.
This is the quadwhoopie up close. It has a sliding-x part in the middle with 2 adjustable whoopie style legs and is the heart of this anchor. The quadwhoopie can equalize about 15-30° angles, which is plenty if you use the adjustable legs to roughly equalize before tensioning. If you have a fairly long anchor, the angle is even greater. Now, the quadwhoopie does limit extension if one of the legs fail. At this point, however, I cannot guarantee that the sliding-x is load-bearing with only one leg. It could be possible for the sling to invert the brummel splices, if you are super unlucky.
In this picture you get a better look at the sliding-x part. It’s only 12cm long. This leaves enough room for the line to settle into place during tensioning and still be equalized afterwards. It can also take care of small side-to-side movements (e.g. massive surf-amplitudes). In order to protect the anchor against a single-point or even a quadwhoopie failure, I installed a second whoopie-variation. This time a twin-whoopie.
The twinwhoopie is the intellectual predecessor of the quadwhoopie. It offers another 2 point connection, but does not equalize as well as the quadwhoopie. Therefore it’s used as a backup sling. It is important to not overtighten the twinwhoopie, because that compromises the equalization abilities of the anchor. Snug but not tight. Instead of the twinwhoopie, 2 conventional whoopies could also be used. The twinwhoopie is a little better at equalizing, but really it’s just in the video to show off. 2 normal whoopies are a great choice for a backup as well.
This is what a complete main anchor could look like. You have the quadwhoopie in yellow, the twinwhoopie in red, an additional whoopie with a grey cover that connects to a far-away anchor point and there is a small guying system in white to pin down the anchor at the edge. Once set the quadwhoopie can accomodate small changes to the direction of the load (when you install a tie-down or add more padding), but if you drastically change the load direction, you have to readjust the legs of the quadwhoopie. This can’t be done at more than handtension, so make sure you orient the anchor roughly where you want it before putting some tension on the line.
To point out the obvious:
This rig is extremely easy to abrade and cut. Using 5-6mm dyneema rope is only sensible if you can avoid all possibilities of abrasion. Tons of treepro is not sufficient. This anchor might be used in vertical walls, where the entire rig hangs freely in the air or when your anchor points are far back and you use an A-frame to redirect the line off the ground.
If you intend to splice your own quadwhoopie, you have to be super accurate with the sliding-x. Remember that one part is always longer than the other. I won’t give a detailed splicing tutorial on this, but feel free to make your own variations!
It is possible to use 2 quadwhoopies to equalize a 4-point anchor. This is slightly more involved. Instead, one could create a quad-twinwhoopie with 4 legs that equalizes perfectly between 2 sets of anchor points which are somewhat equalized themselves. If you’re really ambitious with your splicing you can create a 4-point quad²whoopie, but the sliding-x part is always a little messy.
What is shown here is only the main line anchor. You always need an additional backup. I don’t think this is an adequate anchor to use as a master point, because the dyneema is too easily abraded. Strength wise, this anchor should be good for 50kN, given that the Airbow provides a relatively big bending radius. 6mm dyneema single strand ranges in the 40kN area. You can see, that I tied a big knot in all the excess rope of the whoopie slings. If you’re paranoid, you can also do that.
Special thanks to Stephan Chudowski from raed-slacklines for the dyneema!! Without your contribution, this would not have been possible.