Rigging Math, Who Needs it?

Don’t let the title fool you. I realize that understanding the forces involved and having the ability to figure them out is a key aspect of our field. Having these skills will absolutely make you a better rigger and a stronger asset. I have learned to really enjoy doing the math and I encourage everyone to learn it. Lets face it though, a large percentage of working riggers have no idea what the math entails and only have a vague idea, if any, of the physics involved in rigging. The question I have is, is that OK?   How many guys installing shackles on a beam or tying in points on the ground need a full comprehension of the forces involved?

So my next question is, who needs to know what? Should we have a clear distinction in the field between rigging designers and rigging installers, much like what happens in lighting or set departments. My feelings are that if you are designing a rig, even something as seemingly simple as  “a couple straight sticks with some movers”, you should have a fairly deep understanding of the forces involved and the materials you are using. In most simple rigs though, so long as you follow certain “rules of thumb”, complex math will still not be necessary. If you are designing a rig involving a mother grid and/or large dynamic loads, you had better be qualified. So, for the sake of this discussion, lets separate riggers into two groups, rigging designers and rigging installers.

In my personal experience, some of my favorite guys to work with know very little about calculating tensions, calling bridles or some of the other intricacies of the field. What they are good at is hustling up to the steel, rope management, moving quickly through the roof and several other intricacies that cannot be learned from a book. These skills are much more valuable to me as a crew leader or a co-worker and while I appreciate depth in a rigger, the person who takes every course and garners all the knowledge they can manage, but still can’t work efficiently, or possess zero people skills, or have a poor work ethic, or what ever the issue may be, will not be as helpful to the crew.

Once you’ve spent a fair amount of time in the business your skills will start to be assessed. In my eyes, as a general rigging installer, working under a qualified supervisor, there is a fairly short list of requirements.

1. You need to be comfortable in your environment, for some people this takes longer than others and thats OK, I’m all about overcoming fears. Others seem to never get comfortable even after years in the business and this effects your work. You need to be able to move through varying roof structures quickly, you need to able to work with your hands at heights without too much added thought. I’m not a fan of using guys on the ground who are not comfortable in the air but that is just a personal choice. I know there are some very good ground riggers who are afraid of heights. I tend to think that to be really good at either, you need to have experienced both sides. Certainly the most useful riggers are the  people that you can put in any position.

2. You should be familiar with wire rope. Be able to inspect it and recognize when it should be taken out of service. You should know the common color codes and be able to assemble bridle and deadhang components correctly and also understand why they are assembled the way they are. You should know that two ton motors require 1/2” steel and have a general idea why. I like to think you should know the working load of the most common materials we use but , I know a lot of good rigging installers who can’t or won’t retain this information. I’m happy if I can get guys to stop calling 3/4” shackles “the big shackle”.

3. You need to be able to read the floor at least enough to recognize the correct hoist type and build the proper connection. You should also know the proper way to dump a hoist out of the box.

4. You should be able to tie a couple of knots.You need to be able to tie a bowline quickly, every time, even if you can’t see it and especially upside-down. You will also need to be able to tie a hitch that won’t slip when tying off a screen, banner or whatever(I use a modified clove).

5. You should understand that the forces acting on a bridled point can be much greater than you might think. You should be able to recognize a flat bridle and call attention to anything that may be looking flatter than ninety degrees. You should understand that there is a direct relationship between bay size, leg length and tension, and that if you keep your total leg length around two thirds of your bay size, you will be within safe tolerances.

As far as I’m concerned, once you possess these five fairly simple skills, it’s all about attitude. Do people want to work with you? Are you pulling your share of the load? Can you talk and work at the same time? Are you paying attention? These are the characteristics I look for and I try to make sure the people displaying these qualities are rewarded on my crew. Quite honestly I think just the skills listed above carry a lot of riggers quite far in the industry, including supervisory positions.

I also firmly believe that the more you learn, the more you realize how much you don’t know. I encourage everyone to continue learning, and I like the fact that the industry is pushing for education. I just find there are several good assets to whom rigging is just a small part of their lives. I would hate to lose these guys, some of whom have a thirty year history of safe rigging practice, because of a lack of a certification. The industry already has a time tested method of training people on the job by performing the work, this is the method that has produced the best riggers you know. This has been in working practice for many years with the cream generally rising to the top and very little in the way of memorizing formulas.

Now, if you are designing rigging packages, this is another story. I see a lot of companies sending out lighting and audio rigs with no pre planning and an obvious lack of understanding of the physics involved(especially with small audio companies hanging large stacks). I won’t get into what it takes to be a qualified rigging designer in this discussion, but I do feel that is is a different set of skills than are required to actually do the work.If you are interested in developing more depth as a rigger, there are some good books listed here. I welcome your comments. I also have a post further down the same page discussing some of the work methods above.



1 thought on “Rigging Math, Who Needs it?

  1. Very nice post. Some people seem to get an ego when working at height. I also think the person that can just go about his work in a smart way and just be a decent hard worker will always be employable.

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