Spar pole rigging is one of the most basic rigging systems, one that most, if not all, tree folk are familiar with. In this system, a trunk with few or no branches left is lowered down under control in manageable pieces to the ground. Although this technique is familiar to many, and seems quite basic in appearance, if not understood and carried out correctly it can lead to less-than-positive, if not catastrophic, outcomes.
While the written word and pictures can illustrate some of the forces involved, methods used and pros/cons of spar pole rigging, this should only be considered an introduction and not sufficient for Johnny B. O’Doughnuts to go scrambling up that white pine towering over the greenhouse ready to bring it down “chunky style.” The use of instructional videos through the “Interweb” or DVDs is highly recommended, hopefully followed up with hands-on field-based instruction in the step-by-step process by experienced climbers and riggers. Spar pole rigging is an excellent, safe and efficient technique to have in that mental toolbox, and an understanding of some of the ins and outs of it provided by this column will help Johnny along the path to rigging success.
When 500 pounds doesn’t mean 500 pounds
Forces in rigging is particularly important when the topic is spar pole rigging. Climbers and crews must always keep in mind that when using this technique the climber is attached to the spar, which also provides the rigging point. Thus, whatever forces are generated by the piece of wood are transmitted to the very thing that is keeping the climber aloft, not to mention the climber’s soft tissue and relatively fragile physiology. At a minimum, a 2-to-1 force factor will be present when spar pole rigging.
In simple terms, this means that if the piece weighs 500 pounds, then 500 pounds of force will be required to keep it aloft or control it, which in turn means the rigging point, typically immediately adjacent to the climber, will experience at least 1,000 pounds of force. Needless to say, this can lead to some interesting rapid movements, resulting in bruises, contusions and fractures, or even catastrophic failure of the entire spar itself.
The farther the piece falls prior to coming under the control of the rigging system, the greater the force is magnified, thus a block set well beneath the piece exponentially increases the forces experienced by the spar and the attached climber. This leads to the safest place for the placement of the rigging point on the spar being immediately below the piece, typically near the climber’s tie-in point, which adds its own complications. The reality of spar pole rigging is that reducing the forces experienced is the prime directive.
Energy flows and is absorbed, it doesn’t disappear
Most experienced spar pole riggers have spent years taking every branch off as they ascend the tree, taking the top out upon reaching it, and then working their way back down lowering pieces off the spar. However, field research/testing and personal experience have shown that leaving branches, where possible, attached to the trunk of the tree being removed significantly lessens the forces experienced at the anchor point high up the trunk. By leaving branches on the trunk during ascent, those branches actually absorb and dampen some of the forces experienced by the trunk during rigging, lessening the forces experienced at the anchor point and trunk movement.
This option won’t be possible on every tree and in every scenario, but when able climbers should attempt to create a “chute” that the pieces of the spar can be lowered down through, thus dramatically lessening the forces the spar and climber will experience during rigging.
When it’s not possible to leave branches to absorb energy, the climber and crew should be aware of the heightened forces that will be generated and either reduce the size of the pieces removed accordingly or take some of the other steps described to absorb the force generated.
Lowering is a required skill
One of the best ways to minimize the forces generated at the rigging point is in the hands of the oft maligned but highly influential branch manager. Two primary factors come into play in this force minimization: rope choice and lowering technique. Climbers and crews that get hung up on the strength of the rigging line without considering its elongation or elasticity are setting themselves up for a trip to the land of bad things.
A rope with extremely high strength but no elasticity does not have the ability to absorb any of the energy generated by the plummeting piece, thus all that force goes into the rigging point, spar and attached climber. Therefore, consider elongation of the rigging line along with strength. In addition, the gradual slowing or deceleration of the piece, as opposed to a sudden stop, will lessen the forces experienced at the rigging point.
Using any of the various lowering devices available, such as the Port-a-Wrap III, GRCS or Hobbs, will result in smoother and more controlled lowering than the traditional “tree wraps.” Experienced ground personnel can certainly accomplish smooth, controlled descents with tree wraps, but the use of lowering devices ensures that the friction level is the same regardless of tree species, and makes the operation more efficient by eliminating the tedious process of going around the tree with the rigging line again and again.
The best climber in the area will have an extremely bad day with a branch manager that is unfamiliar with smoothly slowing a piece during its descent to the ground; and climbers would do well to keep that in mind when verbally abusing ground personnel, as even an experienced branch manager can make a mistake after being yelled at one too many times. Situations will arise where a controlled “run-out” of the piece is not possible, perhaps due to hazards or obstacles beneath it, but the crew and climber must simply recognize this and prepare themselves as well as possible for the forces that will be generated and ensure the spar and climber can endure them.
Read more: 5 Tips for Spar Pole Rigging
When you gotta get away
If a crew is felling trees at ground level, a key component of the felling plan is their escape route, the ability to get away is just as important when aloft. After all, when one is 100 feet up in a Douglas fir spar, simply turning and running is not an option. Climbers must have a way to get quickly, safely and efficiently to the ground should it be required; and spur climbing down is not quick, safe or efficient, nor is it an escape route.
There’s a wide variety of systems, ranging from the simple to the complex, that allow a climber to be tied in to either a single or doubled-line system while on a spar. Climbers should choose the system that works best for them. Once that choice has been made, the system must be used when doing spar pole rigging – personal experience has shown that spur climbing down with an injury or while being attacked by insects is not a viable option, nor is it very pleasant.
Cuttin’ with no chuckin’
A climber aloft is required to be secured by two methods while operating a chain saw, and this requirement becomes even more vital when carrying out spar pole rigging. Typically, the cut being made is quite close to the climber’s system, which is preventing him from experiencing the inevitability, and attendant pain, of gravity. Being secured by two methods gives the climber a backup if something goes a little sideways with the cut and a rope or lanyard gets severed. In addition, the way in which the cut is made can affect forces at the anchor point and spar movement.
The use of a 45-degree notch while aloft will cause maximum pushback on the spar right at the moment of separation. Needless to say, this can lead to the climber performing some interesting “dance moves” high in the air. Climbers familiar and skilled with the open-face notch of 70 to 90 degrees will find it equally useful aloft, but should keep in mind that opening the notch too greatly will cause the piece to pull the spar with it prior to separation, once again leading to dance moves. In most cases, the best degree of opening is one that will allow the piece to separate when horizontal or slightly above horizontal with the ground below.
There is a great deal more involved with spar pole rigging than the basic methods, forces and techniques discussed here, but this discussion does provide an introduction to this useful technique, which can lead to safer and more efficient removals. The addition of spar pole rigging to a tree crews’ toolbox will not only help them get the job done, but make sure that when the top goes down, they’re ready.
Editor’s note: This article was originally published in August 2014 and has been updated.