Highline Bolting Tips
The number and type of bolts one can select are dependent on rock quality, environmental conditions and anchor orientation; among other factors. Corrosion, freeze-thaw, exposure can also be factors when selecting the appropriate bolt. Bolting is a skill in itself and it takes time and patience to find perfect placements, no matter where you're placing bolts. This is especially true in softer rock, semi-sketchy looking rock which require longer bolts for added security. It’s best to use glue-ins for this scenario. Hard, dense rock like granite or forms of sandstone might not need extra long glue-in bolts but placement is still critical. Generally, we recommend 3-4 bolts for highline anchors. More than that is overkill and visually disruptive.
Something we touched on in previous articles is threading rope through the bolt or hanger. Standard rock climbing hangers do not allow for threading due to their sharp and abrupt edges. We recommend against using anything but the strongest stainless steel hangers and bolts if using this style of hardware. Glue-ins on the other hand generally have smooth, round eyes that are ideal for threading.
Listed below are a few styles of bolts in common use:
Glue-ins: Glue in bolts usually feature a smooth metal eye with a round profile. They are very handy, as you can thread static rope and other similar anchor materials directly through them and do not need to carry any metal connectors to connect to the bolts. If using spanset though, you’ll need to bring connectors. These are the BEST of the BEST!
Expansion Bolts: Expansion bolts (commonly used for rock climbing) work by wedging themselves into the rock when tightened and have a hanger fixed to the bolt with a nut and a washer. The hanger itself has sharp edges and it is common to connect these hangers to rope or spansets by using quicklinks or shackles. This is a common bolt used for rock climbing, but please only use the strongest option if these are used.
Chain with threaded Rod: This bolting method also allows for the rope threading. These are an inexpensive alternative that people have been using mainly in the United States. The drawback to these is that they are visually intrusive and can corrode quite rapidly due to the numerous metals types involved. The system consists of a 1/2" x 6" wedge bolt with washers and chain-links attached. We suggest using other options because over the years these bolts are going to be a pain to remove and replace.
If you’re establishing a highline and it is possible to rig it safely on natural anchors like trees, boulders, or similar: that is the way to go, rig natural! If you’re repeating an already established line and not sure what it’s all about, try and contact the FA party and rig it the same way they did. Over development (over bolting) is starting to become a problem in some places. Many areas have ethics when it comes to bolting, especially when it comes to rock climbing areas and official parks of any kind. Be sure to research whatever rules apply to the place you want to set up a highline. Do not place bolts for highlines if they’re not entirely necessary or not permitted. A good way to determine if it’s acceptable to bolt in an area is to get in contact with the management group. Management groups can sometimes be state officials, city parks and rec people or park managers. Generally, if climbing anchors have been placed, there is a precedence for bolting. If placing bolts, try to minimize their visual impact on the rest of the environment. You can paint them the same color as the rock or place rocks over them when not in use.
Padding is always an important component to slacklining. Wherever there is possibility for movement or protruding sharp objects, PAD LIKE MAD. Synthetics like rope, spanset and webbing are very susceptible to abrasion and the last thing you’d want to have happen is have a component fail due to overlooking or ignoring a point of abrasion.
Highline anchors are the most important part of your highline rig. If they are not bomber, the strongest mainline and backup systems will not make any difference. It’s the part of the system that should not fail under any circumstances. There will never be a standard for highline anchors because every line is different and we are interacting with the natural environment. The ways to anchor highlines are as diverse as the gaps they are rigged over. The skillset you need to acquire is just as diverse and you need to think critically about each anchor you build and how it can fail. There is no fixed recipe, you must acquire the ability to think critically about your anchors and make sound decisions based on failure modes, load sharing and many other factors that really only come with experiance.