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BASE Jumping: Articles: Jumping: Static Line

Static Line

by admin

The use of a static line in BASE allows for jumps from lower than the altitude it would take to deploy a canopy from freefall, even with no delay at all. Experienced jumpers have made static line jumps from sufficiently low altitudes that survival without a parachute, though unlikely over hard ground, is far from impossible.

In a static line jump, the pilot chute is attached somehow to the object by a piece of 80-pound break cord. The cord generally used in BASE has been tested to very tight tolerances; it will hold until a shock of at least 80 pounds is applied, then will break. It therefore holds the pilot chute to the object through the opening of the container, canopy extraction, and deployment of lines. It breaks, freeing the canopy and jumper, at line stretch.

Static line jumps have the disadvantage, relative to a good PCA, that the center cell is always stripped. In practice, this has a significant effect only for the lowest jumps — and even then, it is often inconsequential. Static line jumps have the advantage that they do not require the presence of a second person, which can be helpful when access is difficult or a lot of work, when descent by ground crew would be dangerous, or when for other reasons the jumper would prefer that other people were not involved.

General Considerations

Although the pilot chute plays little or no role in a successful static line jump, a large pilot chute should nevertheless always be attached. In the event of a premature break in the break cord, a large pilot chute will often suffice to deploy the canopy on time. If the break cord goes before the container opens, clearly a bridle without a pilot chute will do nothing. The jumper should also carry a knife to cut the break cord in case he or she can’t jump, but needs to get away after the break cord has been tied.

Early static line jumps, and many modern jumps, were done without the carry-on attachment described below. A number of very acceptable techniques can be used with systems such as that shown on the right; they generally share the disadvantage that they leave gear at the exit point which needs to be either cleaned up after the fact, or left there. More recently, a system has been devised which allows the jumper to take all gear with him, while not presenting a significantly increased risk of hang-up or failure. This system is discussed in the next section.

Carry-on attachments are easy to build. If you can’t build one, you should have no problem finding someone who can build one for you. Accepted techniques for jumping without one exist, but are probably too varied and numerous to discuss in appropriate detail here.

The recommended procedure for a static line jump is largely common to jumps with and without a carry-on attachment:
  1. After the container is closed, pass a rubber band over the PC and slide it up the bridle to the container. You’ll use this later. For best results, use the same rubber band you would use to close your tailgate (and not the black ones!!)
  2. At the exit point, find a suitable place to anchor the static line to. Don’t use a wimpy little strap of steel, find something that doesn’t look like you will pull it off and find yourself doing a 2-way with the chunk of steel that used to be attached to the bridge. Most handrails are good. Give it a tug and make sure it’s as solid as it looks.
  3. Tie the bridle or attachment to the object using a surgeon’s knot in a piece of 80 lb break cord (described below for the carry-on system).
  4. Start s-folding the bridle at the static line attachment point and stop about 24? from the container. Use the rubber band from step 1 to contain the s-fold. Don’t use a double wrap. This stow is not meant to hold anything. The only purpose is to keep the bridle neat and staged while you get into position and exit. The bridle should easily unfold as you fall away from the object.
  5. Ensure that the bridle runs straight from your container to the anchor without passing under or through anything that will prevent it from loading correctly.
  6. Climb into position so that you’re standing next to the SL anchor. Try not to stand off to one side of the anchor, as this may lead to heading problems. As you climb over, watch your attachment; you want it to be free and clear when you’re ready to jump.
  7. Exit with some forward movement so that you clear the object, but don’t huck out there. Minimal forward movement will create less of a pendulum effect on opening and you’ll be able to control the canopy easier if you’re close to the ground.

Always be careful with your rigging. If possible, have somebody check it before you exit. The first static line jump is always a bit of an excercise in faith — if you’re unsure, a SL attachment setup can be easily tested on a balcony with a bridle and a weight.

Carry-on Static Line Attachment

Dexterbase Rigging carry-on S/L attachment

Most carry-on static line attachments are similar to that shown on the left. Their use is straightforward:

  1. Girth hitch the white loop to the bridle/PC junction. Alternatively, the attachment can be tied to the bridle using break cord as shown on the left below.
  2. Pass the red end (away from the white end) over the anchor so that the white line faces away from the object.
  3. Tie the two red ends to the bridle/PC junction with a surgeon’s knot using a piece of 80lb break cord as shown.

Submitted by admin on 2007-06-13 | Last Modified on 2007-06-27

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