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Issue #16: July 23, 2015
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Strap In! A Conversation with a Straps Fabricator

By Patti Miller, Aerial Animals

 

We have made and sold over 300 sets of aerial straps. We produced our first set for our daughter in 2012. I didn’t understand why straps or “two pieces of webbing with a bit of stitching” should cost $200-$300. So, I went to REI, bought nylon webbing which I was familiar with from rock climbing for $1 per foot, and my husband used our industrial sail-making sewing machine to make them. I confess that my husband and I are chronic “Do-It-Yourselfers.” In 2001, we bought a sailboat, taught ourselves to sail and proceeded to spend the next five years sailing all the way around with world. During that time, we became experts at DYI. Well, our daughter didn’t care for our straps. So, we began research and development.
 
Straps Materials
The most commonly used straps materials include, tubular nylon, cotton, polyester, aramid fiber (Kevlar) or a combination. Your choice may be influenced by strength ratings, cost, comfort, color selection, length and width options, hand loop size or lack of one, and other factors.
 
What strength do you need? Aerial people talk about Minimum Breaking Strength (MBS) which is the point the equipment fails, and they talk about Working Load Limit (WLL) which is the MBS multiplied by a safety design factor which is determined by the manufacturer. The customary industry standard is a 10:1 ratio because this provides an adequate margin of safety. A 100-lb person would need a 1,000-lb WLL. Another consideration is dynamic load generated as the user moves. We did tests with a 160-lb professional straps performer on one of Ludwig’s portable rigs using a pulley system with static rope. When he did a double-arm roll down with five wraps, the maximum load was only 210 lb. When he did dislocks and other moves trying to generate more load, we briefly saw 462 lb. A reputed rigger reported on Facebook that when he measured a 150-lb performer on straps, the maximum load on the system was 760 lb, a double roll down was 350 lb, and a single arm roll drop fast was 400 lb. His rigging included 3/16" cable run through a series of pulleys to a double brake flying winch. There was 50-70 feet of cable in the run, and applicable cable stretch. Based on this, I am assuming Ludwig’s Portable Aerial Rig absorbed some of the shock. I plan to repeat our tests from an I-beam. Note that you can further soften the impact and reduce the dynamic load using a bungee pack. Too much dynamic load will damage a performer’s shoulders quickly.
 
The stitching used to make the attachment or hand loops and thread choice also affects the overall strap strength. I consulted with an expert hang gliding/parachute harness maker to design a stitch pattern that would give us the strongest possible seams. In destructive tests, our webbing fails before our seams. Our seams have never failed. The “W” pattern provides the integrity. We add a little box around the “W” to provide a finished look and to prevent fraying. The webbing end sometimes frays and the box seam may break as a result, but that is not an integrity issue.
 
While there are many very strong webbings available, strength alone is not the only factor for determining which webbing is best. Nylon is slippery and it hurts and burns. Cotton alone has been known to fail catastrophically without warning. Kevlar cuts and burns. I also found the cover over a core could bunch. I opted for webbing with a synthetic core and cotton cover. This webbing provide good strengths but does not cut into the performers' hands. My webbing manufacturer says the MBS is 2,400 lbs, but after being made into straps, we consistently measure break strength of 1,700 - 1,800 lb. The results were the same for my hand-dyed straps and for straps which were heavily used for over two years. Note that it gradually lost strength. There was no catastrophic failure. Even after the failure as seen in photo, most of the nylon core was still intact and still held a load of 250 lb. We could not get it to snap and break catastrophically.
 
 
I think our MBS and longevity is good, but not great. I wouldn’t want people using a single strap or doing big dynamic drops on my straps without some sort of shock absorber. Rock climbing manufacturers often recommend replacing soft goods after five years. I am still trying to determine a recommended lifetime for our straps. I asked several manufacturers to make stronger custom webbing for me, but they wanted a minimum order of 50,000 feet and also declined when they learned the application was aerial acrobatics. I continue to search for new materials.
 
Dyeing my straps was another adventure. I first used “craft-store” dye and it faded immediately. I next went to Procion dye which reacts and bonds with the cotton, but not the nylon. When I tied to dye large lengths of webbing and then make straps, I had some problems with the nylon shrinking more than the cotton and our straps weren’t consistently the same length. Now, we first make the straps, dye each set individually, dry them to length on a rack under tension, and finally hand stitch the leather chafe guards. This works, but is time consuming. It only takes us about one hour to cut and sew and one hour to dye, but rinsing out the dye can take hours!

  

You can and should wash your Aerial Animals straps. If they have been dyed, they may bleed. So wash separately. Wash them in a bucket with warm water and a detergent like Joy which rinses out more quickly. Rinse several times and hang to dry.
 
Some people use stoppers or “safeties” to cinch the hand loop tighter. These are often made from webbing or leather. I stock “cinches”, but don’t advertise them because I think they are a huge liability in the US for the manufacturer. I don’t want people to rely on these for safety until I do more testing.
 
People want different things. That’s why there are many makers and types of straps. I decided to make a product for people who want a reasonably strong, comfortable strap in fun colors! We do many customizations such as length, hand loops size, adjustable length, leather-covered hand loops, unique colors, multi-colors, hand painted, and more. I didn’t see anyone else filling this niche. Besides the straps vendors you find on the Internet, Climbing Sutra and AMSPEC, Inc. make industrial stunt aerial harnesses and straps.

Straps Rigging
There are aerial straps and aerial straps rigged with winches. Most of us don’t have access to a winch and are limited by ceiling height. Straps rigging can be 30 inches long. In general, it costs more for the shorter rigging. Most people want three swivels, so each hand can spin and the whole body can spin. Popular rigging options are shown in the pictures below.



 
Note from Delbert: If you use quick links (Maillon Rapide), as shown in the photo above, I recommend that you "mouse" the quick link by wrapping electrical tape around the screw coupler and the body (two wraps will do fine) to help ensure that the coupler does not unscrew during use.
 
 


 

I see the first set-up most often. It uses climbing swivels, a bear claw, and either carabiners, quick links or shackles. I like the triangle plate in the second photo because we can make it out of steel, it wears less than the aluminum bear claws, and it looks nicer for performers. The rigging in the third photo eliminates two levels of links. Some people use a delta or triangle instead of the pear-shaped quick link. I was concerned the swivels would bang together, but I know people who like this setup and I don’t hear it when they perform. This configuration seems to be the best value in terms of shorter length and lower cost especially when shackles are substituted for the top and bottom quick links. The fourth configuration, which we call the “Tri-Fly,” uses Rock Exotica Rotator Shackle Swivels and is only 12 inches long. I think it looks nice, especially for professional performers. I am still searching for a swivel with shackles on both ends. Petzel has recently released an open swivel which eliminates all the links and potentially the rigging plate. I haven’t tested it yet, but will. There is a clever locking-triangle plate shown in the FEDEC Straps Manual. I also love the rigging I have seen made from sailing stainless steel hardware. The rigging was compact and pretty, but the weakest link is only rated for 400 lb and it is expensive because it’s stainless. I mostly use Fusion swivels because they are good quality and lower cost than other climbing swivels, although they are a bit bulkier.

Strap Trends
Growth in straps! I am not going to buy 50,000 ft of webbing yet, but straps are growing in popularity!  
Recommended Straps Resources
  • The Fédération Européenne des Ecoles de Cirque professionnelles or FEDEC Instruction Manual 03 Aerial Straps  2012, is a must read for every straps person! It includes history, equipment overviews, and conditioning exercises  http://issuu.com/fedecpro/docs/fedec-sangles-en-web/1?e=12051196/10919560
  • Sanglier Facebook group is a great place to connect with other straps people from around the world, share videos, and ask questions.
  • While the FEDEC book and/or Sanglier FB pages are great resources, straps is not an introductory discipline for people wanting to try aerial, and they absolutely need supervision from a competent straps coach (not a general aerial coach) to train anything beyond basic conditioning. Even experienced aerialists benefit from working directly with a coach to learn the basics of positioning and to have a spotter on hand when learning straps technique, because shoulder damage can happen very fast otherwise.
Back to the beginning, “Why should two pieces of webbing cost $200-$300?” While DIY can work, having done the work to make sure our straps are safe for the way aerialists are using them today and to stay abreast of new trends in usage and the availability and integration of new materials and equipment to continue to make a good and safe product, winds up being a significant investment. I found out that it’s not really just two pieces of webbing in order for it to work well and safely.
 
We're excited to meet the needs of the community - tell us what you want! Please, visit us at our Facebook group, Aerial Animals. You’ll see some of our latest creations including cinch loops verses open loops, metallic painted straps, adjustable-length straps, leather-covered hand loops and more.
 

 

Need to learn rigging math? Check-out my book. You can purchase a special spiral-bound edition at www.SpringKnollPress.com.
 

Delbert L. Hall

ETCP Certified Rigger - Theatre
ETCP Recognized Trainer

 
Copyright © 2015 Delbert L. Hall, LLC, All rights reserved.


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