Smart Anchor Building
Highline main anchors never stand alone. You must always create a backup anchor system in the event of a main anchor system failure. A backup anchor usually consists of individually isolating each bolt to the masterpoint and/or creating an entirely separate backup anchor system. This is an aspect of redundancy that should always be kept in mind. Bolt isolation can consist of wrapping webbing, rope or any other suitably strong material between the bolt and the master point. If you have a 3 bolt anchor, you will need to isolate each of the three bolts to the masterpoint. And before calling the anchor good, tie off the tail ends of the webbing to either the masterpoint or a bolt, just in case.
Extending the Anchor
Extending the anchor masterpoint beyond the cliff edge is an important piece of the rigging safety equation. Just like in rock climbing, you do not want your main safety device (ie. the rock climbing rope or slackline webbing in our case) running over any sharp or abrasive surfaces. This can lead to premature failure of the webbing due to abrasion. The simple remedy to this is either extending the anchor beyond the cliff edge or placing an “A-frame” underneath the anchoring material to provide clearance for the webbing. This is where static rope becomes your rigging friend because you can adjust the length of the anchor to the exact condition whereas rigging with spansets, you’re kind of stuck with a fixed length. You can add an additional layer of protection by wrapping at risk webbing with a velcro sleeve or some form of padding.
The biggest takeaway from this article is; Build bomber main and backup anchors! On a well built rig there should be no reason for the backup to ever engage, it is there to protect against unforeseen extraordinary circumstances, but that is exactly when you'll need it.
Make sure you build anchors that effectively share loads and that do not exceed 60 degrees at the outermost bolt angles. When building anchors be sure to fashion them so that they limit the possibility of extension to eliminate the potential for shockloads. And make sure the masterpoint is not going to rub against any rock or object because it could create a potentially dangerous situation.