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.

 

 

Communication is Key

I find it amazing how many ways a person can interpret something as  simple as “Take this, and put it over there”. Getting your point across accurately and briefly can be surprisingly difficult, even face to face. Now, add into the mix, you are 100′ apart during a noisy load in.

Communication amongst your crew is critical, and you should develop a protocol. Sometimes we have radios provided, this makes the job much easier, but still not fool proof. Often the radios are low quality and/or we are not provided enough channels to separate teams. When you are provided radios, it is important to practice good radio etiquette. When someone speaks to you on the radio, it is important to respond. It can be very frustrating giving instructions into the radio, not knowing if the person on the other side is receiving. Either give a quick “copy” into the radio or, if your hands are busy, a simple call down usually works. It is also important to be as brief as possible on the radio, there is often someone else using the same channel, sometimes needing to give a timely instruction.

I find the most useful tool in communicating to be very simple, but often overlooked, PAY ATTENTION! If you are watching the people above you, and the people in the air are watching their ground person, radio communication will be minimal. Learn and use hand signals, I like to tie on a rope and simply, hold out my hand, with a little belly in the rope. The up rigger should see this as a sign to float that leg to apex(waving your hand in a large circular motion is also common). How does he know he is at apex from 100′ away, because you tell him with a large sideways wave of your arm. This is a universal symbol to stop, whether you are pulling a point on the in or letting one in on the load out, you should be watching your ground rigger for that stop signal. Whatever hand signals you decide on, don’t try to be subtle, up riggers usually need to see large movements from far away. Once one leg is at apex, you can tie on and float the other leg if you are sending out a bridle, again, the up riggers need to be looking down and watching the ground rigger as the wire rope and connections pass through their hand, go slow as they check every connection, once the hoist hook is past the ground riggers face, take it away. This is especially important if you use pulley systems in your house, just because you have eight guys on a rope, does not mean the point should fly out once there is a knot tied into the basket, you have to watch the ground and go slow until the hook is clear.

A good team of up riggers will not need to be told where to go point by point, you should be able to read the floor from the steel in most instances, when things are iffy, ask for a laser. If a point is not hitting the mark, you shouldn’t need to be told to slide it, you should be doing your best to spot the point from the beam. As a ground man, you can mostly lead your crew with few words, put your laser, or stand on the next point. If it’s a bridle you can communicate this by holding two hands up like a “Y”, if a deadhang, just hold up one hand. Keep an eye up, you may need to breast something out of the way, you may see something the up guy isn’t seeing. Just because you are not physically doing something doesn’t mean you can be inattentive. If you can’t work and talk to your buddy, then don’t talk to your buddy. Keep one step ahead of the up team, if they see you laying out the next bridle they will know right where to go.

On load outs especially, radio communication should be almost nil, but you have to pay attention. I can’t stand seeing ground guys standing there holding a chain with no one anyone near breaking it. Or up guys tying into points that are not landed when there are motors in boxes. Again, pay attention to what will be coming in next, watch for ropes hanging, keep an eye on what area the up riggers are and conversely the up teams need to watch what the ground riggers are landing first. The most common mistake a see on load outs is bridles coming in unevenly making it very tough for the ground person to control, if you see your leg going slack and getting out of the ground persons control, you need to slow down and match your partner. If you need to stop for some reason, make sure you communicate to your partner to stop, otherwise the chain will move horizontally on the floor creating a hazard. If your chain is whipping all over the place, either on the in or the out, you need to match your partner better.

You will find that if you practice all of these techniques, or develop your own communication protocol. You will be much better prepared for the times you are not provided radios and you will be able to keep the shouting to a minimum.

Building a Strong Crew

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There are a lot of things you can do as a lead rigger to make your job easier, in my opinion the most important one, is surrounding yourself with good people. I was very lucky when I got my job as the lead, the venue brought in Jimmy Mullen and Steve Thonus to help steer me down the right path. Both of these guys have been rigging since I was a kid and taught me some invaluable lessons.

One of the first things Jimmy drove into my head was the importance of having some control over who is on your crew. You want to surround your self with the best players available. I love when I look around the room and there are several guys on my crew who are more experienced than I am. The idea that you need to surround yourself with people who suck to make you look better is just pure backwards thinking. In a perfect world , you, as the lead, will be able to hire your own crew, purely based on talent. Unfortunately , this is usually not the case. Many of us have to deal with union seniority, friends of the Business Agent or foreman, the whiners who always seem to get their way, or whatever else may be the case.

What Jimmy and Steve both expressed to me was that the talented riggers will move on, the slugs are here to stay. You have to do what you can do to limit the slugs on your crew. These people are like a cancer, they will suck the life out of your crew, poor work ethic spreads like a disease. Keep in mind that the good guys on your crew have to pick up the slack for the weak links, this pattern incubates bitterness on your crew. One of the most important things you can do to endear yourself to your crew, is to make an effort to eliminate the weak links. This is no easy task, and sometimes seems impossible, but you have to keep making the effort or things will get complacent.

You also need to recognize the difference between a slug and someone who may just be more of a type B personality, who needs a little push. We often speak of a riggers depth, it’s great to have good, fast, “shackle installers”, but it’s also important to have a core of guys both upstairs and down who understand the theory behind what we do. Encourage education, the International training fund will reimburse most educational costs. It’s also important for you to share information, I invite every body to come learn how to mark the floor. All my information is yours for the asking. I’ve never understood the practice of hoarding information. I like to think that if I get held up, there will be three guys stepping up with a laser and chalk who know the room well. Your crew will respect you more if you show them that you trust them to have your back, just as you should have theirs.

With that said, you also need to be constantly looking for, and recruiting, new talent. You already know who the hard workers are in your local, try to convince these same people who are talented electricians and carpenters to come over to the dark side. I try to actively do rigging and rescue practice sessions, give people a shot to come harness up and pull a point under a no pressure situation. I’ve been very surprised by some of the talented riggers who have become a part of our crew from these training sessions. People that it never would have occurred to you could pull one point, let alone lead a crew through the roof like a champ.

One of my favorite stories to tell is about Ren Cain. Here was a young kid that was afraid to stand on a six foot ladder. He came to one of our practice sessions a couple of years ago, he was walking in the center of the catwalk, white knuckling both hand rails, looking white as a ghost. I basically wrote him off, figuring he just came to say he was here. I went through my usual routine and took several people out and walked them though the routine. At what seemed like the end of the day, I was giving my little wrap up, I see Ren, harnessed up, center of the scoreboard catwalk, bracing himself. I will tell you, I was impressed, this kid was frightened, but looking to overcome it. As someone who was also pretty terrified his first time out, I have an idea what he was feeling. I walked him out and he did what he had to do, slowly and carefully, but he did it. It was a slow learning curve for Ren but now, less than a year later, he’s one of the faster guys on the crew, and he brought his step dad into the mix, one of the guys I had been trying to recruit since the building opened. He has also made several contacts and branched out on his own to become a pretty solid steel climber on some big outdoor gigs.

In my experience, you will always need support from outside locals. I’m always on the look out for the A-players when I’m out working in neighboring locals. There are very few, if any, venues that will support a crew of riggers full time so most of us are willing to travel to rig in different venues. You need to have a long list of good riggers outside of your core crew to insure that when the larger calls come around, you’re not just filling the numbers. When that friend of a friend comes through and all you see is their rope tail dropping in for work all morning, make sure to get that phone number. Production riggers are also a good resource, most of these guys don’t mind pulling a rope when they’re between gigs, gather as many numbers as you can. You also need to do what you can to make the outside guys want to come back. Make sure these are the first guys to get cut when the crew goes down, make the guys who don’t pull their weight stay for trim. Make sure these guys know that you appreciate them coming, you will need them over and over again.

You should be in constant communication with your BA/Call Steward to keep them informed about who’s working out and who isn’t. It’s hard to fill large calls, you need to make it easier on whoever is doing it by providing them a long list of talented riggers. You have to learn to evaluate talent quickly, because once these guys get on the rigging list, it’s tough to keep them off your calls no matter what their skill level.

I think it’s a constant battle to get past the point where 10% of the crew is doing 90% of the work, and maybe even a losing one. But you have to at least make sure that, as the current ten percenters move on to $greener$ pastures, you have young talent ready to step into their shoes.

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Tools of The Trade

(A Guide for Arena Riggers)

 

Ok, you’ve decided that you’re going to take this seriously and you need to tool up. I can’t tell you how many times I’ve seen riggers show up on the call empty handed. If you plan on working at height, you’ll need to purchase an OSHA approved full body harness. The days of riggers climbing scaff in sit harnesses, or strolling out onto the beam with no harness, are gone. There are lots of options,  you will find most guys using Petzl or Yates harnesses, these are great brands and trusted for a reason but, contrary to popular belief, you don’t need to spend $400 on a harness and another $180 on a double lanyard.If you look around at PK Safety you will find an assortment of OSHA compliant full body harnesses at reasonable prices. Personally, I prefer a harness with central and sternal D rings as well as the mandatory dorsal attachment, so that I can comfortably  perform a rescue.

Next on your list is a rope, A rigger without a rope is, well as my mentor Jimmy Mullen would say “what the hell good are you without a rope, you may as well go downstairs and push boxes”. As far as I’m concerned there are only a couple of options, 5/8″(16mm) solid braid multifilament polypropelene or a 5/8″ (16mm) dynamic line, I prefer the latter. As far as length, my standard answer is “20′(7 meters)longer than the roof is tall”, this works as a general rule but there are rooms where a longer rope is necessary if you are running lines to the catwalks.  Some guys will only need one rope but a good rigger is worth their weight in gold and you should plan on getting around. You can get a decent deal on a 600′ (183 meter) spool of rope and cut from that as you start working in different rooms. I like All Line Inc as a supplier.

I see guys pulling points with smaller diameter lines, usually because they prefer to pull points through a small wheel and it won’t accommodate the larger line. These people are making it harder on themselves. By the time your small diameter line passes over the small diameter pulley the added tension you’re creating negates the advantage of the wheel, and the thin diameter line is not easy to grip or friendly on your hands. For the most part, if you’re not dealing with extreme heights or weights, the easiest way to pull is hand over hand, from the beam. When you are in a situation that calls for pulling through a wheel you should use the appropriate tools. Pigeon Mountain Inc has a wide selection of steel pulleys, CMI  also has an assortment of steel pulleys intended for use with 5/8″ (16mm) rope, they also make a rope grab of the appropriate size. I’m also a big fan of the Gibbs ascender in a 5/8″ (16mm) as a rope grab. Put these together with a steel rescue carabiner, a small steel carabiner and a couple RSI omnislings and you have a solid set up for hauling points to the ceiling. I see the Petzl Protraxion in use a lot, I like it in ways but, for me, as stated above, I don’t like to use line within the recommended range for this device, so it doesn’t fit my needs. If you do use the Protraxion you should always use a carabiner in the bottom and top attachment points to prevent unwanted opening.

I also feel a drawstring bag can be very useful for carrying a radio, bottle of water, small tools or anything else you need and don’t want to drop. There are lots of companies that make chalk bags which is a common preference, I prefer the Yates small bolt and tool bagYou will also need some head protection, personally I prefer to use a climbing helmet in the air, and a hardhat on the ground. Whatever your choice make sure its ANSI Z89.1 compliant, most climbing helmets are not.

For me these basic tools cover most arena rigging needs in the air, as you progress in your work you will acquire whatever other odds and ends you find you’ll need to fill out your kit. I’m leaving gloves out of this as I feel it’s a personal choice, I generally don’t wear gloves and if I do I prefer fingerless gloves for handling shackle pins.

If you want to complete your kit you will need a couple of tools to work on the ground. A laser level is a key tool in leading a team though the roof, there are a lot of options and I think I’ve tried them all. Of the easily available choices, I like the Bosch GPL3, the PLS3 is a good deal brighter and I do own one and like it but I find that they don’t hold up to the rigors we put them through. A good ground person will also carry a tape measure on their belt. A distometer is handy to have but certainly not essential for most, in my opinion.

So what’s in your kit….

Marking The Floor

 

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The quickest way to get off on the right foot when a show comes into your venue is to be able to efficiently call bridles. The last thing a production manager or road rigger wants to see is the house rigger looking up, scratching his head or franticly punching numbers into a calculator or phone.

There are several methods to calling bridles and you have to find what works for you. If you’re lucky someone will be willing to pay for you to lay out the show before hand and, with an accurate overlay, you can pre-figure all of your bridles. I developed a spreadsheet to figure loads and leg lengths. That works to an extent, until you find out that you have the wrong plot or the show moved upstage three feet, and the reality is, most times you are not given this time. I see a lot of people using phone applications to figure bridles lately, this could be a great tool if you knew how to use it quickly and efficiently, but I haven’t seen that happening yet. Bridle charts work well if you take the time to set them up correctly. When I first started to make charts I would do a chart for each bay, figuring off of an even bridle and writing down how many inches each added link gives you. Note: You will find that as you add links and your long leg becomes a larger percentage of your bay size, you will get more movement per link.

Eventually I found that I could make one chart from the center of the room out, again using a computer program, the Pythagorean formula or simply estimating you can figure pretty close to what each link will give you. As you hang points in your venue you can adjust your chart as you find how things hang in the real world. I always adjust the long leg unless there are very special circumstances, I would suggest that you start by doing the same, short leg adjustments get tricky quickly.  I have three charts for my room as the bay sizes aren’t consistent from the North end to the South, you may need more charts, in a simple grid you would only need one.

I simplified my chart to approximate every one foot move, link counts in between are easy enough to figure in your head. My chart for the Prudential Center looks like this:

Prudential Center South Side

What you will find is that most road riggers will lay out the room with three tapes. Next to the center tape, most will write every point locations measurement from center(the really nice guys write that # in every point). Now you can simply reference your chart to see that  a point at 43′ from center will need 7 links of deck chain. At this point you should be able to just look up into the bay to determine which leg to add links to.

I’ve found that the next step to really knowing your room is to memorize some key numbers. The first numbers to get into your head are all of your dead hang and even bridle locations. In the chart above; 6’9″, 13’6″, 20’3″, 27, 33’9″, 38’9″, 43’9″, 51’9″, 60’3″. If you know how many inches of movement you get for every link of deck chain, you can figure a lot of points in your head from these key numbers. If someone puts a point on the floor at 14′, I know without any calculations that, in my room, I need to add one link of deck chain to the onstage side of an even bridle to hit the point.

Once you have those numbers down pat, I like to also memorize where a full deck chain hits, in my case 4’6″,9′, 18′, 22’9″, 31’6″ etc… So now any point within a couple feet of center or within a couple feet of the edge of each bay you can figure in your head so long as you know how far you are from center of the room. It may seem like a lot of numbers but I found I was able to commit them to memory pretty quickly. I rarely have any reason to pull out my chart and I think as you get to know your room the goal should be able to walk onto the floor with a tape measure, laser and some wet chalk and mark the floor quickly and accurately, often only needing the chalk. Checking a chart is a pain in the ass.

If I’m in a new room, or need to figure a point in a bay without measuring from center of the room. I find the quickest way to be simply measuring the bay size and marking center of the bay. Make sure you’re measuring from the center of the beam. Next, measure  how far your point is from the center of the bay. Based on the length of your leg and its ratio to the bay size, you should be able to approximate how much movement per link you will get and you can add links appropriately, in my venue I get a little bit more that 5″ of movement for the first link added. If you haven’t read Bridle Dynamics by Fred Breitfelder I highly recommend it. He gives a great perspective on the relationship of your bay size to your leg length and how to approximate link counts. Keep in mind this quote from Plato’s Republic
“The most important part of any work is the beginning”.

Ben Kilmer
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