Access on doubled rope with the ZIGZAG
Classic technique that allows the access rope to be left in place, while working in the tree on a second rope. It is suitable for major, long-term projects.
- Carefully read the Instructions for Use used in this technical advice before consulting the advice itself. You must have already read and understood the information in the Instructions for Use to be able to understand this supplementary information.
- Mastering these techniques requires specific training. Work with a professional to confirm your ability to perform these techniques safely and independently before attempting them unsupervised.
- We provide examples of techniques related to your activity. There may be others that we do not describe here.
Note: in this document the name ZIGZAG means either the ZIGZAG or ZIGZAG PLUS models.
There are many access techniques suitable for different work objectives in the tree. The access technique includes a choice of rope installation, and the ascent technique itself.
Two precautions are recommended during access:
- During ascent, the ASCENTREE's cams should be backed up, for example with friction hitches.
- The user must be able to descend in an emergency, without significant change to the equipment setup.
During access, the ZIGZAG's rope is set up in double mode, with a redirect point on the ASCENTREE. Following access, during the work phase, the arborist may choose to use the ZIGZAG either in double mode, or in single mode with CHICANE, and sets up the work rope accordingly.
- The access rope can be used by multiple arborists to ascend into the same tree, for aid and rescue, and possibly for descending.
- The ground person can pass equipment up via the access rope.
- The arborist goes to the top of the tree to install their work rope on a definitive anchor. So they are certain of the primary anchor's suitability for the work.
- Aligning the strands is necessary before access.
- On long ascents, the rope can slip through the ZIGZAG, changing the ergonomics of the ascent.
The work rope must be long enough to return to the ground (doubled) from the top of the access rope and/or the chosen primary anchor point.
To descend, undo the mule knot and operate the ZIGZAG normally. The ASCENTREE stays in place on the rope.
Backing up the ASCENTREE with friction hitches
The type of backup depends on whether the rope is installed with the ends blocked, or not.
a. Doubled rope, ends not blocked
Complete backup with a friction hitch on each strand. The branch isn't choked: the rope can slide on the branch. Warning: approaching the top on a large-diameter branch, the separation of the rope strands can disable the cams, or impede progression.
b. Doubled rope with one strand blocked at the level of the branch
A friction hitch on the blocked strand is enough for a complete backup.