All About Spansets

Span·sets - A lifting sling made from several wraps of natural polyester fiber which is then covered by a double-wall tubular webbing which is sewn together at the ends. Often refered to as Polyester Round Slings, spansets have many practical uses in various fields involving rigging.

Spansets have been around for a very long time and have typically been used in the industrial rigging market. The slings themselves offer a magnificent strength-to-weight ratio compared to steel slings or chain. The ultra low stretch also plays a big role in their usability. At the working load limit of each spansets, they are only stretching 3% of their length.

Another thing that makes spansets so effective is the way they are constructed. First they take a single strand of natural polyester fiber and wrap it several times around the full length of the spanset, threading it through a double-wall tubular webbing during this process. Then they take the ends of the tubular webbing and stitch them together. The double-wall tubular offers an extremely durable abrasion cover that protects the load bearing fibers within.

Now, how does all of this relate to slacklining? Well, spansets are considered to be the most bomb-proof sling out there for anchoring slacklines. Their high strength-to-weight ratio, supreme strength, ultra-high durability, and extremely low stretch make them superior slings for every type of slackline. Even the weakest of all the spansets out there (read: Purple Spansets) are more than strong enough for even the largest of slacklines.

Alright, enough with the salesman talk, now we can get into the good stuff. How are these slings used in slacklining? What are their limitations? What do all the ratings mean on the slings? I will answer all these questions below.

How are Spansets used in Slacklining?

Spansets are used in many different ways in slacklining. The most common is probably anchoring tricklines and longlines. Both of these forms of slacklining require a TON of force to be put on your line, thus the need for ultra strong anchor slings. The way these slings are rated, we can get nearly double the vertical strength of the slings by simply wrapping them around the tree and connecting the ends with a shackle (more later).

Another way spansets are used for slackline rigging is for highline anchors. Up to 4 bolts can be equalized using the sliding-x configuration (whole other article) with a spansets. Anything beyond 4 bolts becomes too much of a hassle to use spansets.

Basically, anytime that you need an absolutely bomb-proof anchor for your slackline, you should be using spansets.

What Are The Limitations of Spansets?

There are a few drawbacks to using spansets. One is that they are all a set length. When you purchase a spansets, you are asked to choose a length. This length is something that you cannot change about the spanset, it is fixed. That means that if you have an object that is larger than your spanset that you need to wrap, then you will either need to get a bigger spanset, or connect two together with a girth hitch (or some other form of connection). This can be a major drawback if you use a large variety of sized anchors because you will need a large number of spansets to accomodate all these sizes.

Another drawback of spansets is they tend to be quite heavy, especially the larger sized ones. This can be a problem when doing highlines with long approaches. This can be reduced by sticking with the Purple-size Spansets.

What Do the Various Ratings of Spansets Mean?

If you have ever seen a spanset, you probably have noticed that they all have tags sewn onto them with various information about the sling. This information is very important as it contains all the strength properties about the sling. There are a few key things that are missing from these tags that is often overlooked when rigging with spansets.

The basic tag on a spanset will look like this:

The code on the sling refers to the kind of sling that it is. On this partical spanset, OL1 means that it's the purple size spanset. The date refers to the date that the sling was manufactured. The length on the far right refers to the length of the spanset, measured end-to-end (see above). Then the three numbers on the bottom of the tag refer to the strength of the spanset for various rigging situations. The number on the bottom left is the strength for vertical pull. This refers to using the sling end-to-end and pulling streaight along the length of the sling. For us slackliners, this is the least common way we use spansets. The second number refers to the strength of the sling in choker configuration, which is basically a girth hitch. You may use this on a tree where you don't want to have tri-loading on your anchor connection. The third number refers to using the sling in a 90-degree basket configuration. Often times slackliners will refer to wrapping the tree with a spanset as a basket hitch, but this is not entirely true. Wrapping a tree with a spanset and connecting both ends to a shackle or some other connection device creates an angle in the sling. This angle causes increased loads in the legs of the sling, which when added together are larger than the total load at the master-point of the sling. For this reason, the rating is not quite the same as a true basket hitch. Here are a few photos to demonstrate the concept:

	Angles in Degree Factor 90 1.000 85 0.996 80 0.985 75 0.966 70 0.940 65 0.906 60 0.866 55 0.819 50 0.766 45 0.707 40 0.643 35 0.574 30 0.500

This is why it's very important to watch the angles that you are experiencing in your rig when using any sort of sling. The small the angle at the load, the larger the forces are in your sling. Here is a fairly comprehensive chart showing various rigging conditions and the strength of the spanset when used in that configuration:

This concludes our article on spansets, if you have any questions or comments, please ask them below in the comments section and we will do our best to answer in as much detail as possible. Thanks for reading!