Know Your Lines

Courtesy of Performance Designs

Features
Thursday, October 1, 2020

Different line types create confusion among skydivers of all experience levels. What are the different types of lines? What are the pros and cons of each? Which size line is best for you? Which kind of line is on your canopy now? When will you need a reline? So many questions! Get ready for some line knowledge overload.

Line Types

There are four primary line types used for canopies: Dacron, Microline (also known as Spectra), Vectran and high-modulus aramid (HMA).

(Bonus: visit tinyurl.com/linetypes for video explanations by Performance Designs Vice President John LeBlanc!)

So, why do these properties matter and what do they mean for your skydiving?

Dacron‘s elastic properties are more forgiving of an abrupt opening than other line types. That is why Dacron is a popular choice for students, camera flyers or anyone else who wants to minimize the results of a hard opening and is not overly concerned with the addition of more bulk. Dacron is the largest of the line choices and is not a good choice for someone looking to minimize drag or pack volume.

Microline is the most abrasion-resistant of the line types and is less susceptible to wear from desert environments than HMA or Vectran. However, Microline is not as dimensionally stable as other line types, meaning that the canopy’s lines tend to shrink as the canopy is jumped repeatedly. The shrinkage is caused by several factors, including friction created by the slider as it descends during the opening. After several hundred jumps, some of the lines may be a few inches shorter than they were when the canopy was new. This is what we mean when we say a canopy is “out of trim.”

Vectran (including orange-coated Vectran) is very dimensionally stable, meaning it will hold its trim extremely well. This makes it a standard choice on high performance canopies. However, it is more prone to abrasion than Microline, especially in sandy, desert environments.

HMA has similar properties to Vectran, but with smaller pack volume and slightly less drag. It has a softer feel than Vectran and is susceptible to abrasion and snagging, especially in sandy environments.

Line Size (It Matters)

Performance Designs categorize line sizes into four major groups: comp, light, standard and heavy duty. In order to decide which category is best for you, you must first consider several factors, including what size canopy you own, what kind of skydiving you do, if pack volume or drag are concerns for you and how often you are willing to get relines. Each line-size group has its own uses. The pros and cons are outlined in the chart below.

When Do I Need a Reline?

Pop Quiz Time:

If your lines are going to break, it will typically happen:

A| On opening
B| During flight
C| On landing
D| Any of the above

Many of you probably answered “A,” but that’s not entirely correct. In reality, your lines can break on opening, during flight or on landing, so answer D is correct. If you’re flying a faster, high-performance canopy, you are testing and straining your lines throughout each canopy ride. That means that if you have a very worn out lineset, you are putting yourself in a situation where a line could snap and give you an unrecoverable malfunction just a few hundred feet above the ground. If you think that sounds far-fetched, it has happened many times before. To prevent these malfunctions, it is vital that you monitor the conditions of your lines closely and replace them as needed. When inspecting your lines for wear, you should look for a few key things:

1| Broken carriers: Broken carriers can significantly reduce the strength of your lineset and are a sign that the lines are nearing the end of their life. Take special care to inspect around the link loop (near your slinks or hard links) and around the stabilizer above the cascade, as these are high-wear areas that are sometimes overlooked.

2| Line fuzziness: Simply put, if your lines look more like a strip of Velcro than a line, it’s probably time to replace them.

3| Flight characteristics: Aside from the visible condition of your lines, it’s prudent to monitor how your canopy is opening and flying. If you start to notice undesirable flight characteristics, it could be a sign that your lines are going out of trim. This is especially applicable to a Microline or Dacron lineset.

To illustrate how your lines lose strength over time, we took some linesets at various stages of life and submitted them to a series of tensile tests. The results are shown on each photo as a percentage of strength loss. It’s important to note that these lines could have any number of jumps based on the environment and packing area. The “heavy wear” examples could have 200 jumps in a desert or 600-1,000 jumps in a grassy environment with a clean packing area. There is no hard rule about how many jumps a lineset will last. In any case, the heavy-wear samples shown here are well past the point at which they should have been replaced.

We hope this gives you some insight on how to monitor the condition of your lines. If you have any questions about the condition of your lines, ask your manufacturer or your local rigger. The bottom line is that if you find yourself with ragged lines, you should replace them before they snap on a skydive. The money you save on trying to squeeze 10 more jumps out of your lines pales in comparison to the cost of replacing your canopy if you lose it on a cutaway or the cost of medical bills if you snap a line on landing.

About the Author

Performance Designs has designed and manufactured sport parachutes since 1982. Since then, it has introduced cutting-edge developments such as Microline, cross-bracing and zero-porosity fabric, all of which endure as standards in today’s parachute industry. Jumpers can find more information on PD’s products—including the line types available on each of its canopies—at performancedesigns.com.

Getting more granular than linesets or even individual lines, let’s talk about the pieces that make up your lines. Take a look at these ultra-close-up photos of 500 HMA line:

Your line is actually a weave made up of several “carriers” woven together. It’s easy to see carriers with the naked eye, but you can see them closeup in the photo on the right-hand side. The condition of the carriers is often what manufacturers will look at to determine whether a canopy needs a reline.

As we increase the magnification up to four and five times, you can begin to see what makes up the carriers. These individual pieces are called “yarns.”

Here you can see a close-up of a single yarn. We’re getting pretty small now, but we’re not quite at the smallest unit of your line. Yarns are made up of “filaments,” seen running parallel here.

Finally, we get all the way down to an individual filament. For reference, the object on the right side is a bartack needle. These tiny filaments ultimately come together to form the lines that keep you suspended from your canopy thousands of feet from the ground. Pretty neat, huh?