Tree Climbing Systems
Two parts are needed for a arborist climbing system. The first is a progress capture to hold the climber in position on the rope. This can be done either through using a rope to tie a friction hitch or through a mechanical device. Progress captures used for arborist work are designed to also allow the climber to descend the rope without having to be removed and replace with a specialized descent device.
The second part that is needed is a way to advance up the rope. A strong person might use their body to pull themselves up the rope but this is very tiring. To make this easier either a handled ascender connected to a foot loop or a foot ascender is used. A handled ascender attaches to the rope above the progress capture device and the climber stands in the foot loop to move themselves up. A foot ascender attaches directly to the climbers boot and the climber then stands to push themselves up the rope. The progress capture is then allowed to move up the rope and the process is repeated until the climber gets to their desired position in the tree.
MRS and SRS Climbing
Arborist climbing styles can be grouped into two main categories depening on how the rope is setup. They are stationary rope systems (SRS) and moving rope systems (MRS). Both systems have their benefits and drawbacks.
Moving Rope Systems (MRS)
Moving Rope Systems (MRS) is also known as DRT (Double Rope Technique) and DdRT (Doubled Rope Technique). MRS systems are usually the first type of rigging setup taught to beginning climbers. In an MRS system the rope goes over a tree branch, or friction/cambium saver, and moves while climbing into the tree. Since the rope is doubled, the climber only has to lift half of his body weight. The drawback is twice the rope needs to be moved through the system. 20 meters of rope needs to pass through the climbing system to ascend 10 meters into the tree.
Stationary Rope Systems (SRS)
Stationary Rope Systems (SRS) is also known as SRT (Single Rope Technique). In an SRS system the rope is fixed and does not move with the climber. The end of the rope is either tied to an anchor on the ground or in the canopy of the tree. The climber moves along this fixed rope. SRS systems are faster since for every meter of rope that passes through the system the climber ascends a meter. This can be more tiring though since the climber is lifting their entire body weight instead of half like with an MRS system. SRS systems therefore require better technique which requires more practice.