Now here is an interesting idea in the world of rigging and climbing trees: moment.

Taken right out of Chapter 1 in The Art and Science of Practical Rigging by Peter S. Donzelli and Sharon J. Lilly, “moment is the rotational motion caused by a force acting some distance from a pivot point.” (17).

A swinging climber, a tagline pulling over a high stump.

The pivot point is important to understanding the concept of moment. In the two examples I illustrated (swinging climber, hidden ground), the pivot point is either the climber’s anchor or the hinge on the high stump as it’s falling. The distance from those two pivot points (the rope, essentially, which is the generator of force along with weight) is incredibly crucial to understanding moment as an actual product.

“The value of the moment is the product of the force and the distance from the pivot. Both of these quantities are vectors, so a special product is used. Only the component of the force perpendicular to the distance is used.” (17)

I would like to use my previous two examples, because I think they work well on the level of also furthering this concept of the value of moment. You can feel moment, as both the swinging climber and on the ground tag lining a high stump over. In both scenarios really, we feel moment in the form of exposure (exposure to the vectors in play). Imagine being on a long, extended limb walk, and with every step you get farther away from your anchor, the pivot point, you feel more and more exposed. More anxiety creeps in and the need to either set a redirect or put your lanyard loom like a dark cloud. That, in effect, is moment acting out on your consciousness. Also, to utilize the other scenario, the farther you move away from a high stump, the more force you are able to direct onto the hinge of the tree, and the less exposed you are to the falling wood. Moment is very intricately tied to the feeling of exposure in rigging and working trees. The more control we have over moment, the safer we become.

“Because moment is a product, even a small force can be significant if it is applied at some distance. This is an advantage when pulling over a tree, but it is a liability when climbing or rigging” (17).

Moments can be controlled in many ways. We control moment with mechanical advantage (increasing force), or with an M rig or V rig in a moving rope system (increasing friction and creating a second pivot point). Moment can be mitigated with a drift line, with a GRCS cranking, clicking, a hinge closing and creaking. These are the sounds of moment working itself out.

Tree work is a long string of defining moments, if you think about it. Some resulting windows breaking and side walks shaking, some result in a first place Work Climb finish, and others, a long forgotten divot in time. Moment is everywhere.

It is a sum of forces.

It is interesting to think about breaking down moments, like breaking apart an equation and looking at each variable. When looked at from a granular perspective like this, we can better reach an understanding of the system of forces acting in moment as an exploration of those vectors.

Cease the moment!