May 16, 2012
What line type should I have on my parachute? This is a question that rarely comes up until someone has already decided on what canopy to buy, but then causes a reason to pause because no one wants to spend that much money and make a wrong decision. But who do you ask? What’s the right answer?
Skydive Spaceland’s Pro Shop has more than 15 years of experience in gear sales and testing, so here’s some information in an effort to help reduce the confusion.
The type of line(s) used in skydiving are mostly derived from the sailing industry and are available in different blends of nylon(s) in many different weaves, the most common being:
These types are available in different weights (tested breaking strengths), sizes, and sometimes colors. They also have some very different properties as we’ll discuss.
Dacron: Many new(er) jumpers have never seen this type of line, except maybe on some brands of tandem canopies. It’s a very large-diameter, white, heavy-feeling line that is very dimensionally stable. This means that over the life of the line type, it doesn’t change very much in length, either through shrinking or stretching. It is a somewhat elastic line type, which doesn’t mean you can use it for bungee jumping! Rather, the weave allows it to stretch a bit on openings but it returns to its original dimensions afterward. It is also sometimes available in black as seen on BASE gear, or red as seen on CRW (canopy relative work) canopies. One of its drawbacks in sport skydiving is the bulk of the line when packed, which causes more room to be needed in the container. It also creates a large amount of drag, reducing the airspeed and the performance of canopies; this drag is especially noticeable on smaller, higher-wingloaded parachutes.
Spectra: This is the most common line type in the skydiving market today, and for good reason. It is a low-bulk, low-drag line that wears very well and is very hard to break. However, it is not very dimensionally stable because it is susceptible to shrinking when heat is applied. With a canopy, heat is applied in the form of friction every time the slider comes down the lines on openings. Since the slider rubs more on the outside and control lines than it does on the center lines, the shrink is often uneven causing the lineset to go out of trim. An out-of-trim lineset causes poorer openings and performance than the parachute is originally designed to have. Even with this characteristic, it is still a great choice for line type because long before the lines get worn enough to break, they are out of trim and the performance has degraded enough that the jumper wants to replace them.
Vectran: This line type was developed and introduced to the industry as an alternative to Spectra, since it is also low-drag and of equal strength while also having the benefit of being heat-stabilized. This means that effectively it doesn’t change in trim over the life of the lineset. This does create a new problem, however, in that the lines will wear out and begin to break BEFORE the performance of the parachute begins to degrade. The solution for this problem is to visually inspect Vectran lines on a very regular basis, which is something that needs to be learned because Vectran lines show wear differently than other line types like Spectra.
HMA: HMA is the buzz word in skydiving these days. It seems to hold everyone’s attention, but why? It’s very low drag, it is very dimensionally stable, and it does not change in trim. It’s very strong and wears well, so it lasts a very long time. So why isn’t every canopy lined with it? It is so small that it’s hard to sew accurately and where it is sewn is a high-wear point. It does show wear in a very different way than most line types, and most importantly it doesn’t cope with damage very well at all. Other line types can get dirty and still last a long time, but HMA’s life is greatly reduced by damage, dirt, and physical wear; thus, it needs to be cared for very well. Additionally there are many weights (breaking strengths) on the market today, but very few are suitable for most sport skydivers, so care must be taken in choosing the HMA you use.
So what’s right for you?
First, not all line types are available on all types of parachutes. The manufacturers have designed and tested their parachutes and released them to the public only with the most successful combinations. Their testing may have shown that a particular combination’s benefits do not outweigh the cons, and do not offer it. This means you should exercise caution and not select third-party manufacturer’s line kits. They may not meet the standards of the manufacturer and if they are made of untested dimensions or materials, this may produce unforeseen problems.
On many entry-level parachutes, the options are Spectra (sometimes called Microline), Dacron, and Vectran. Spectra is possibly the best choice because of its safety record, although Vectran may be a good compromise as long as the jumper is the type who is going to be very hands-on with their equipment. Dacron is rarely chosen since it’s selection is very likely to also require a larger container.
All jumpers should be aware of the expected lifespans of their linesets, and know to check or have checked the condition and trim when openings and performance degrade or visible wear begins to show. Most linesets have a life of between 400 to 600 jumps, but many factors can shorten or lengthen that lifespan. Remember to take care of your parachute, as it takes care of you.