Teaching, training and understanding the forces generated while rigging trees can be challenging. Even as experienced arborists and professional trainers, we have had the experience of looking into the eyes of rigging trainees and knowing, “They don’t get it!” This was the motivation behind “Feeling Forces,” a strategy that can help improve comprehension while training arborists about the forces generated in tree-rigging operations.

This article is an overview of the motivation behind developing Feeling Forces and several of the key concepts employed in the training. By the end of the article, you will know:

• Adult-learning principles: How and why we apply them during the training.
• Feeling Forces programming and examples of experiential learning to demonstrate fundamental rigging principles and terminology.

Exercise 1 photos a, b & c: “Feeling Forces” is a strategy to teach arborists about the forces generated in tree-rigging operations by having participants feel forces mimicking those they will be putting on a tree. Here, in exercise 1, the participant’s torso and legs represent the trunk of the tree, and the arms are the limbs.

Before we get too far, let’s be clear about what this article is not. It is not intended to imply that Feeling Forces is new and the only way to teach. It also is not meant to be a technical explanation of the forces in rigging. Feeling Forces is just one tool and approach that can be applied to help educate arborists about fundamental rigging principles, and is supplemental to the training you already have.
Development of rigging instruction

In our experience as trainers, we have drawn pictures of trees illustrating rigging operations, used angle-deviation charts and applied equations to evaluate forces at anchors and to explain theoretical force. We have had some success, but also have had trainees nod their heads while saying, “Yeah … we get it … kind of.”

Compression and tension photos a & b: A small stick can withstand a significant amount of force when pushed or compressed from each end (a, top), versus how easily it will snap when bent (b). All photos courtesy of the authors.

One winter day, we found ourselves on a job site with a learner relatively new to rigging. It was too cold for dry-erase markers, and we didn’t have access to the internet to reference any charts, so we picked up a gallon jug of water (mostly frozen), a rope and a pulley to talk about forces. Our learner acted as the tree, and we had them feel the forces of the rigging operation. It was easy to see the “Aha” moment in the learner’s eyes. This let us know we were onto something useful.

Our approach is not novel. We have learned from mentors who have demonstrated different ways to learn through doing and feeling. Using these concepts and an approach of try, learn and improve, we created what we call Feeling Forces, an experiential learning program intended to be flexible and easily digestible to optimize our training time and prioritize our adult learners. Bite-sized portions are prioritized over dumping buckets of information on people. Feeling Forces is a series of short exercises focused on the forces found in climbing and rigging operations.

Adult-learning principles applied
In training, we frequently find ourselves explaining and demonstrating. In our experience, and I am sure in yours as well, this approach is a starting point, especially in the development of practical arborist skills. Explaining and demonstrating has value when illustrating a technique or a process. However, with this approach, we have only started supporting learning, the seed has been planted. For adults, learning occurs when a set of conditions are created. The following are some of the principles that motivate the Feeling Forces programming.

Why, and WIIFM? (what’s in it for me?)
Simply, “If I know the benefits of learning, I am more likely to engage.” Establishing key takeaways (learning objectives) prior to the exercise establishes early buy-in with the learners. Many learners have rigging or climbing experience, and most can recall a close call or an incident when a rigging operation didn’t go well. Failed rigging operations can have a profound impact on your team’s health and safety. This represents an obvious and natural benefit for the learner to engage with rigging-forces education.

Self-directed or internal motivation
Simply, “I learn best when I am motivated to learn about the subject.” The learner may feel, “I am motivated because I could immediately apply the skill, and I can see how it benefits me.” Also, “If learning means I have a marketable skill to support myself, there is a reason for me to learn that skill.” Feeling Forces is intended to improve one’s overall understanding of the impact of rigging on the working platform. We have found most see a natural benefit to this approach and engage in the program and, in turn, seek to apply it.

Exercise 2 photos a, b & c: In exercise 2, a participant supports a load with a pulley. First, the person feels the weight of the piece being pulled straight down by gravity. In 2b and c, tension is added on the other side of the rope and the person feels the piece getting heavier. This is the result of both parts of the rope being under tension.

Problem-solving orientation
Simply, “If I know this will help me solve a problem that I have, I am likely to show interest.” Consider the following questions.

• What potential outcomes exist when I apply force to long lever arms in rigging operations?
• How can I create compression?
• How can I use leverage to my advantage?

We often ask these questions to get participants thinking about different approaches to rigging and climbing. Frequently, participants leave the exercise with some mental pictures of how to solve these problems.

Fundamental rigging principles and Feeling Forces
We have an axiom, or accepted truth, in tree rigging. Tree parts are more stable when the forces applied compress them, as opposed to bending or leveraging them. Consider a pencil or small stick that can withstand a significant amount of force when pushed or compressed from each end and, comparatively, how easily it will snap when bent. Let us illustrate this and some of our programming. (Compression & tension photos a & b)

In Feeling Forces, the participant is the tree. Participants are asked to support a mass, simply a collection of atoms. As illustrated, the mass, or in this case a rope bag, represents a piece of wood being rigged or a climber. While supporting the mass in different configurations, ask, “Do you feel more stable or less stable?” Participants should consider, “If I feel unstable, the tree will also.” Trees, however, cannot stabilize by moving their feet or flexing muscles like the participant. Typically, the participant will feel more stable when the force is not bending or pulling them.

We have found you only need a short piece of rope, a couple of pulleys with slings and a weight with a handle. Before trying any of these exercises, consider the learner and ensure they are not overstraining. Heavy objects are not needed.

Choosing tie-in or rigging points
In our first exercise (Exercise 1 photos a, b & c), the torso and legs of the participant represent the trunk of the tree, and the arms are the limbs. Participants will support the mass as illustrated. Start by suspending the mass on the shoulder (Photo 1a), then progress to holding the mass vertically, with a straight arm (1b). Finally, transition from a vertical orientation toward horizontal (1c).

Within each element illustrated, we find principles that are tied to the experience of the participant. When the participant is supporting the load close to their torso, they feel stable. This represents compression. When the load is being supported away from the torso, we have bending or leverage. This is an important principle. Applying force to a lever arm creates force amplification. In this case, the total weight of the piece hasn’t changed, yet the result is a greater force being felt or applied at the pivot or tree union.

This exercise reinforces the idea of choosing tie-in points (TIPs) or rigging points near the branch union on the central leader, and preferably around vertically oriented limbs.

Tension and forces
In Exercise 2 (Exercise 2 photos a, b and c), we have a participant supporting a load with a pulley. There is a stopper knot near the pulley ensuring the rope does not run freely. In Photo 2a, the person feels the weight of the piece being pulled straight down by gravity. In 2b, we add tension on the other side of the rope and, despite the piece still weighing the same, the person feels the piece getting heavier. This is the result of both parts of the rope being under tension.

Without accounting for friction at the pulley, we have a 2X force amplification being felt by the person. In Photo 2c, we apply even more force amplification by slowly applying the 2X force to a lever arm. In most cases, the person has a very hard time supporting this, and the arms get pulled all the way down. If it were a tree, we would have some explaining to do to the client.

Exercise 3 photos a, b & c: Here we explore the effects of angles in rigging. When both parts of rope are parallel, the force amplification is greatest. As the angle is opened, the force amplification is reduced. But be cautious of the resultant vector!

Rope angles and force amplification
In our third exercise (Exercise 3 photos a, b and c), we begin to explore the effects of angles in rigging. We have a similar starting point (Photo 3a) as illustrated in the Exercise 2 photos. We apply tension, and our participant feels the resulting force downward. Then the facilitator, while maintaining the same tension on the rope, opens the angle (Photo 3b). When a rope used for rigging makes a change in direction over a pulley or a branch, this is referred to as a deviation or redirect. This angle deviation results in the participant feeling the load getting lighter, and they also feel a slight pull in the direction of the facilitator. This pull is referred to as a resulting vector.

Exercise 4, photos a, b & c: Two pulleys may not be as stable as you think. When tension is applied (4b), the participant feels stable at their feet, but they feel their arms being pulled together. Multiple suspension points can work to your advantage or disadvantage depending on how the platform is being loaded.

This theoretical direction of force can be visualized by looking at the direction of the sling on the pulley, or, in this case, the becket on the pinto pulley. This happens to reliably bisect the angle between both parts of the rope. When we open the angle to approximately 120 degrees, the participant will feel approximately the weight of the rope bag. Simply put, angles created by the rope can be used to estimate the direction forces are being applied and reduce force amplification. What direction of force is present in Photo 3c?

If you look at the becket on the pinto, it illustrates the direction of force. This is putting leverage on the participant, making them unstable. They can feel their heels coming off the ground. We use this exercise as a caution regarding securing a lowering device away from the base of the tree without a redirect. The resulting direction of force could create a lever arm on the whole tree! This could cause a failure.

More on angles
Let’s explore angles further. If one pulley is good, two must be … gooder? If you consider Exercise 4 photo a, two pulleys may not be as stable as you think they would be. When tension is applied, as illustrated in Photo 4b, the participant feels stable at their feet, but they feel their arms being pulled together. This illustrates an important principle. Multiple suspension points can either work to your advantage or disadvantage. It all depends on how the platform is being loaded.

In the case of Photo 4c, we make a slight adjustment in the position of the pulleys and ask, “What do you feel?” Typically, the response from the participant indicates the weight feels heavier, but they are able to support the load, as the arms are not being bent or leveraged. This exercise reinforces the strategy of purposely utilizing redirects in the tree to apply compressing forces to limbs.

Expanding the concept
These exercises illustrate just a few examples of rigging concepts that can be experienced in the context of Feeling Forces. Rigging concepts as fundamental as friction and as complex as rigging and climbing highlines can be explored using Feeling Forces. We have been working to include span rigging, double-
whip rigging, speed-line rigging and other rigging techniques in our programming. We look forward to seeing what other ideas folks come up with!

Beyond the basics: This Feeling Forces program demonstration focused on the forces potentially generated in an advanced technique, such as a highline. This demonstration engages many learners simultaneously.

Conclusion
Providing effective training on the forces applied to trees when rigging can reduce the likelihood of arborists causing tree failure. The concepts of tree biomechanics and rigging forces are technical and challenging to teach. Feeling Forces is a tool in the mental toolbox that may help connect valuable information with your learners. Feel free to add it to your next training session and modify it to make it work for you. We have learned and borrowed from others, and hope you will do the same and share!

Corey Shepard, CTSP, is an arborist skills trainer based in Lansdale, Pennsylvania, for the Davey Tree Expert Company, an accredited, 53-year TCIA member company headquartered in Kent, Ohio.

Emmett Shutts Jr., CTSP, is a Connecticut Licensed Arborist and manager of arborist skills training at The Davey Tree Expert Company.

This article is based on the authors’ presentation on the same subject at TCI EXPO ’24 in Baltimore, Maryland.