Personal Safety System
Before actually connecting the mainline and backup line to the anchors you must remember to install the leash rings and the rest of your Personal Safety System (PSS). The personal safety system is what actually keeps you, the highliner, connected to the highline. In addition to the rings, there is a leash and harness that complete the system. One of the most common yet comical mistake riggers make is to build the entire highline system and forget to install the rings. To combat that, try to work in a few "ring checks" during the rigging process. If you fail to install the rings the first time it just means you have to deconstruct the system a bit and get 'em on there. In this article we will cover the 3 components of the Personal Safety System; leash rings, leash and harness.
As mentioned above, the rings are part of the PSS that is built into the highline. They slide behind you around the webbing, connected to the rest of your PSS. We use drop forged rings with no welds in order to maintain a smooth, consistent surface for the interface between the webbing and PSS. The reason we say no welds is because welds can contain impurities and can corrode over time, especially in salty or corrosive environments. The corrosion can also create burrs that could damage your slackline. The process to make a welded ring is much different than drop forging and does not give the same desirable mechanical properties to the material. Rings used for highline leashes should have a MBS of at least 5,000 lbf.
NEVER USE CARABINERS AS LEASH RINGS; NEVER!!!
Carabiners are not designed for this purpose, they can be cross loaded and break when whippers occur. They can also potentially cut your webbing with the edges of the gate. The first fatality in highlining happened while using carabiners as leash rings. Shortly after the accident, the practice of using forged rings was adopted by most if not all highliners.
Depending on strength and material properties, people tend to use single or double rings for their system. We prefer using doubled rings because it increases the bend radius of the webbing when the rings are loaded. This decreases the stress concentration at the point of contact. Weight is a factor as well. Steel rings weigh more and have more mass than aluminum rings. But aluminum can deform under a much lower load. In most cases, we recommend doubling rings (aluminum or steel) together with some tape. Always inspect your rings for burrs and deformation before and after use.
The highline leash is generally constructed with climbing rope threaded inside tight fitting tubular webbing. This type of leash is advantageous over just a piece of rope for a number of reasons. It is slightly thicker and stiffer making it easier to handle, untie and maintains a more consistent feel as you're walking. Most leashes sold by slackline companies are about 12 ft long to accommodate the figure 8 knots on each end; one going to the rings and the other going to your harness.
When tying your figure 8 knots be sure to leave at least a 10" tail for tying a back up knot; though some choose to tape the tail to the leash at the rings to eliminate the added mass of the second knot. The backup is intended to keep the knot from working itself lose. Also, be sure to finish and dress your knots. This means to make sure every strand is running perfectly as the knot is intended and it has been pulled tight to set everything. Finishing and dressing your knot will also make it easier to untie after repeated whippers. not finishing and dressing will make your knot more likely to work itself lose and that's something we never want to have happen.
The last component to your PSS is the harness. Highliners have adopted climbing harnesses for this purpose. The reason for this is they work perfectly for the application and are already designed with safety in mind. When putting on your harness it is important to do it correctly and follow all safety checks that one would normally follow for putting on a climbing harness. Make sure it is sized well, tighten down the waist-belt and leg loops for a snug fit, be sure the leg loops are not twisted, that all cinching straps are doubled back through their buckles, and monitor for ware and damage over time.
When tying into the leash, tie in with a figure 8 knot in the location you would when rock climbing; at the waits belt and leg loop tie-in points. Do not tie into your belay loop. When tying your figure 8 into your harness follow the same steps you did at the leash rings; 10' minimum tail, finish and dress the knot. Most choose not to tie a backup knot at this point due to the mass being right at your crotch. It can be done for safety but sufficiently finishing and dressing the knot should suffice.