Want a Skinny, Light Tag Line on Your Rappel from a Climb? Consider These Risks, First

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In this video, I am using a Dyneema cord that was developed for sailing, but applying it as a tag line for a rappel. For those of you not in the know, a tag line, in climbing, is a line that is used to move material rather than people. It is not designed to take climbing weight and falls. In the case of a rappel, it is used to pull down the rappel line after the rappel is finished. This allows a climber to use the full length of the climbing rope for a rappel, rather than doubling-over the climbing rope, and thus making the rappel only half as long.

The tag line material I am using can be found, here, at 1/8 inch or 3mm thick.

But is it a good idea?

In project management, (of any kind: software development, building roads, whatever), professionals will talk about the “constraint triangle.” Basically, you can pick any two of these three: speed, quality, or cost. If you want to cut the budget, you can build at a high quality but do it slower… or keep the same speed, but lose quality… and so on.

When it comes to climbing gear, I think of things kind of analogously, but we have cheap, light, and robust. We can have light gear, but it will either be not particularly durable or will not be cheap.

Given that the cost of raw materials are not that flexible, what we normally are confronted with is a loss of robustness.

What do I mean by robust? Well, I mean both durable and able to be used for many uses. Why the combination? Well, in climbing, we are under constant force from gravity. The risk of falling at an accelerating rate of thirty-two feet per second per second (the constant rate of acceleration for an object free falling under Earth’s gravity until we hit terminal velocity), is always there. So, that tends to make durable and able for many uses mean something close to the same thing.

Take the skinny tag line. Like I state in the video, it simply doesn’t have a tensile strength that is sufficient to handle climbing fall forces. Basically, if we took a lead fall on it, it may break. Is that a failure of durability or of the wrong use? Well, kind of both, right?

I wouldn’t use the skinny tag line to make an anchor. It’s so thin that a comparatively brief period of rubbing back and forth across rock (compared to a thicker material) could sheer through the line. Is that a durability problem or a misapplication? Well, kind of both, right?

So, when it comes to light gear, I accept the climbing gear version of the constraint triangle. If I go light, and with the price of ultralight materials being pretty much standard across the industry, what I am left with is the durability/limited-application constraint. If I am getting lighter with any piece of gear, I try to be mindful to ask myself what the gear’s limits are. What uses are still proper for the material? More importantly, what uses no longer are appropriate?