If you’re like most skydivers, you have a troubled history with deployment bags: ’D-Bags’, by their most common (and oh-so-charming) nickname.
This misunderstood bit of fabric—technically, part of your container—is rather precisely sized to nestle snugly into the main tray, and to contain your main parachute in a similarly congenial hug. (That is, if you use one…and, come to find out, not everyone does.)
With all that said: those snuggly metaphors tend to perish on the packing mat. Typically, wrangling the parachute into the D-bag is the act that inspires the most cursing when we’re learning to pack—or when we’re packing a slippery new parachute. The process can feel more like a life lesson in patience and control than a blessed opportunity to set oneself up a good deployment.
Let’s move our focus from the former to the latter, shall we?
In this issue, we’re going to repair our relationship to the D-bags in our lives: specifically, how you can work with your friendly neighborhood D-bag to set the stage for a good deployment.
The first thing to remember is that a “good deployment” always happens in sequential steps: a ‘staged deployment’. The five-stage process always looks like this:
The jumper sets (which is to say: pulls out and releases) the pilot chute.
The pilot chute inflates and the bridle extends, resulting in the removal of the locking pin from its loop.
The D-bag extracts from the container.
The parachute lines separate from the D-bag.
The parachute unfurls from the D-bag, with the slider (fingers crossed) performing its sacred role to modulate the speed of canopy inflation.
With that in mind: how can we help the D-bag along?
Arguably, the first place to start is by addressing step four where it starts: by adjusting the way we secure the lines to the D-bag. Even minor changes here can influence the deployment to a surprising extent. Why? Because the lines need to release in order, smoothly and consistently—in an environment where great forces are being exerted on them—at speed. Luckily for us, this is not impossible.
Most skydivers use either elastic bands (“bungees”), tube stows or a free-stow method to organise the lines on the bag, so let’s look at each in turn.
How to Bungee
Elastic bands for skydiving purpose come in three sizes:
9mm wide by 50mm long: the standard bungee, and the most common size in use. These are typically sized to be wrapped around the line bight twice (or, in other words, “double-stowed.”). A complete wrap around the lines (which is not created using a single stow) is the trick to the even tension that good deployments crave.
9mm wide by 30mm long: “Mini” bungees for canopies with modern lines, not as commonly used. (No need to double-stow these.)
16mm wide by 50mm long: for tandems only, and—even then—not used as often as the standard 9mm x 50mm.
And that brings us to the ever-polarising Tube Stow.
The name “tube stow” (“Tube Stoes” by original branding) refers to the fact that, instead of being flat, as a bungee is, they’re little rings of tubular silicone. They can last for hundreds of jumps.
Personally, I am no fan of tube stows. Here’s why:
The standard 9mmx50mm bungee is used by the vast majority of skydivers for a reason. They are inexpensive and extremely easy to source. The bungees we use are quite specific for skydiving, with a very specific amount of rubber used in their manufacture. Good bungees will hold your lines in place and break easily during the deployment sequence: a key feature that tube stows are designed not to replicate. A bungee that breaks during deployment has potentially prevented a malfunction by not allowing the line stow to lock. Why would you want to, just for a little more convenience on the packing mat, test your luck with a stow that is designed not to break?
If you do insist on using tube stows, hark: the long degradation cycle can fool you, so watch carefully. You can recognise a tube stow that’s past its useful service life by noticeable perishing in the silicone and/or stretching. (If you see this, please don’t be tricked into thinking it’ll be okay for “one more jump” just because your the stow in question has lasted a hundred and still forms a closed loop. Many a reserve ride was born in this way.)
Checking Your Work
All bungeed up? Great. Let’s do a quick inspection.
First, let’s check that you have enough unstowed line between the last stow on the D-bag and the top of the risers.
Exact dimensions vary between manufacturers, but—as a rule—we generally look for around 500mm. As a reference (and a reference only—check it!), the standard riser length is just over 550mm. When in doubt: rather go too long than too short.
Next, let’s check the strength of your stowing. The going theory is that the stows on your pack job should exert 8-12lbs (~5kgs) of tension. How much is that, you may ask? Pretty easy: you should be able to lift the packed, stowed D-bag off the ground without the lines popping out, but not be able to shake it around up there with any vigour.
Finally, look at your line bights—or the “loops,” or the “excess,” if that’s what you learned to call them: in other words, the length of the line that goes out and back through the bungee. I make mine 70mm. Why? Because that is the length of my thumb, so it’s easy to measure and check the important part: that I’ve made all my bights the same length. (If your thumbs are wildly out- or undersized, there’s no shame in that; just go for a bight length of at least 50mm but no more than 75mm.)
One more thing: instead of replacing individual bungees as they break, I make a habit of replacing all the bungees after about ten jumps. This keeps the tension differential between bungees as close as possible, setting the stage properly for a smooth, orderly sequence of pops.
How to Un-bungee
Lastly, let’s talk about the “free stow” method.
Semi-stowless D-bags have seen a huge renaissance over the past couple of years. While there’s an ongoing debate as to whether semi-stowless D-bags give better deployments than standard D-bags, in my opinion, they are much of a muchness. I’ve asked around and that seems to be the consensus.
So: why have a semi-stowless D-bag? I myself have one because I’m—well—lazy. With a semi-stowless, when I do my every-ten-jump bungee replacement, I only have to replace three instead of seven or eight.
It takes a bit of practice to lay your lines neatly into the semi-stowless D-bag pocket. If you struggle with this, ask someone on the packing mat to show you the tekkers.
