A proper understanding of footlocking is an excellent addition to a climbing arborist’s repertoire
Footlocking, a method of efficient and speedy ascent into the canopy, has played a role in the tree industry for many years. While the ropes and gear used when footlocking have changed over time, the basic process has remained the same – a case of “if it ain’t broke, don’t fix it.” But the safety requirements around footlocking have evolved to reflect, and hopefully promote, a safer use of this valuable ascent method.
A history lesson
Not that long ago – in fact, within the fading memory banks of more than a few grizzled tree veterans out there – the footlock was performed with no back-up, or unsecured. The climber would ascend his or her line into the canopy attached to the doubled rope only by the strength and dexterity of his or her hands and feet. Should either fade, or the climber simply become exhausted, a quick and painful reminder that gravity was the law was sure to ensue.
This unsecured footlock technique usage even extended to the climbing competitions of the time, with climbers being required to demonstrate an ability to carry out an on-rope rest prior to competing. The idea was that an exhausted climber, or one who found his or her hands and feet growing more clumsy, could slip into the on-rope rest until he or she recovered, and hopefully not slip rapidly toward the unyielding earth.
While unsecured footlocking certainly had a tendency to keep the user’s mind very focused on the task at hand, it also was, and is, a recipe for disaster, soft tissue injuries and orthopedic trauma. Any modern-day climbing arborist using the footlock in the ascent must do so in a secured manner, thus the term “secured footlock.”
Footlocking fysics, or phootlocking physics
The most common method of security or attachment is a length of cordage used to form a variety of hitches around the ascent line, typically a doubled line, then attached to the climber. Modern manufacturers also have developed mechanical devices that can be used to secure the footlock; these methods are becoming more common.
The footlocking technique can be applied in any variety of climbing systems, from single to double rope, and static to dynamic, but its true efficiency is best shown and seen in a static line. Footlocking on a static line, or lines, results in the user ascending at a one-to-one ratio, meaning that all his or her effort results in height gained.
While it may be slightly difficult to conceptualize, footlocking in a dynamic system, where the line is moving during the ascent, means the climber expends less effort due to some mechanical advantage, but has to move twice as much rope, roughly moving 2 feet to ascend 1 foot.
The requirements for the hitch or knot used when secured footlocking are fairly simple; any secure climbing hitch that grips the rope adequately when loaded is acceptable. A wide variety of knots or hitches is used, with more seemingly being developed and promulgated yearly, but the most common is the Prusik.
After the footlocking technique has been practiced and learned into muscle memory, a good footlocker’s body weight is almost never brought to bear on the Prusik or hitch, except in cases of needed rest, repositioning or emergency. The chosen hitch can be formed from a length of cordage tied to itself with appropriate knots into an endless loop, or a spliced/stitched rope tool manufactured specifically for footlocking. The cordage used must, of course, meet the strength requirements for personal/life support in whatever geographical area in which the climber is operating; in the U.S., that’s 5,400 pounds.
In addition, the line used for the hitch should be somewhat smaller than the ascent line to increase its grip when loaded. Climbers using strong enough but extremely small-diameter cordage may find it grips too well when loaded, and is difficult to loosen to continue in the ascent. Should the secured footlock climber choose to use a Prusik, he or she will find forming it on the ascent line is a relatively simple process: The loop or rope tool is passed back through itself three times, forming a six-coil, three-wrap Prusik. Additional wraps/coils will provide more security, but may increase friction, making advancing the hitch difficult.
While there are certainly techniques and tools that can allow a climber to both ascend and descend safely on a static line, the secured footlock hitches/method discussed here is not one of them.
Climbers using the footlock technique on a static line(s), regardless of the hitch securing them to the ascent line, must remember that they’re in a static system. This means their hitch is bearing the load of their entire body weight, instead of the half borne by the hitch in a dynamic system. Thus, the Prusik or chosen secured footlock hitch must be used for ascent only, as an attempt to use it descending may result in an uncontrolled fall due to the change in forces.
This means that users must always have some means of descent with them, and should not count on their dynamic system as this means of descent, as they may need to descend while not in a location where it is possible to switch over safely to a dynamic system. Some common descent devices that can be put into place while hanging on a static line(s) are any of the wide variety of figure eights, Petzl Piranhas, etc.
Footlockers using a single line, with the required training and experience, of course, could certainly use static single-line devices such as the Rope Wrench or Hitchhiker in this application.
The climber’s hands must always remain below the Prusik or hitch, and the length of cordage used should be adjusted accordingly. This practice will prevent the climber from inadvertently grabbing the hitch causing it to release, and leading to an uncontrolled descent in the static system.
Width is bad
A doubled ascent line that is spread apart by being over a branch or through a crotch can cause hitches that are pushed into this spread to fail in a doubled-line static system. The “spread parts of the line will literally push the coils of the hitch apart, reducing their grip. An excellent guideline to avoid advancing the hitch into this spread is to follow a five-to-one ratio; for every 1 inch of branch diameter, keep the hitch 5 inches below the branch.
Additional options to avoid the problem of spread are:
- using friction management devices such as a Friction Saver,
- using the footlock technique on a single line,
- or tying an appropriate mid-line knot, such as the Alpine Butterfly or Blackwater Knot, passing one end of the ascent line through it, and running the Alpine Butterfly up beneath the branch, thereby resulting in a doubled static line with no spread.
Junk and whatnot
Twigs, sticks and even leaves getting between the two parts of the ascent line or into the coils/wraps of the hitch or Prusik may cause it to fail when loaded. Climbers should monitor their hitch during the ascent and remove any debris as soon as possible, as those wee pieces and parts can reduce the grip of the formed hitch on the ascent line.
The secured footlock is certainly a technique that, for most, isn’t picked up “straight out of the box;” and requires a certain amount of focused effort and practice. But once its limitations and advantages are understood, and some effort spent developing the muscle memory required for feet and hand coordination, the secured footlock can provide a safe and efficient highway into the canopy for climbers.
Courtesy of Tree Services Magazine: http://www.treeservicesmagazine.com)