Tuesday, March 27, 2012

How To Make Your Own Umbilical Tethers

Last winter I began using the Black Diamond umbilical ice tool tethers on longer routes, and while soloing moderate routes. I found peace of mind in not worrying about dropping my tools. The BD tethers really look slick, and they work well most of the time. However, during one season alone I had at least a half dozen instances where they inadvertently unclipped from my tools. On another occasion I watched a friend fall while leading and break his tethers - the webbing broke where it meets the swivel.

These incidents left me with a few questions about umbilical ice tool tethers. Were they worth using if they were going to unclip themselves at bad times? Was the swivel necessary, and are the edges of the swivel sharp enough to cut webbing? Could I make a tether setup that was similar but stronger, one that I could clip into anchors with occasionally during transitions at belays and rappels?

My friend Michael Wejchert's homemade tether setup had no swivel, used real webbing and attached to his tools with full strength wiregate carabiners. He likes his setup and has used it extensively for soloing around the Northeast.

I decided I would make my own pair this February. Since then I've used them quite a bit. They're strong, secure and hardly every tangle, even though there's no swivel. Here's a short narrative about how you can do this at home for about $20.

What you'll need

  • 12 feet of ½” tubular webbing
  • 12 feet of the thinnest elastic cord you can find
  • 2 lightweight miniature carabiners – Metolius FS Mini or Camp Nano carabiners work well.

How To Make Your Tethers

Make sure the ends of the tubular webbing are open. If you bought the webbing at a climbing shop they probably used a special cutting tool to melt the ends. Carefully slice the ends without cutting yourself, so that the webbing is a long, hollow tube.

Tie a small overhand knot in the end of the bungee cord. Slide this knotted end of the bungee cord inside the webbing. The first few feet will be easy. After that you'll have to “inchworm” the bungee through by sliding the webbing down the bungee periodically.

The barrel knot that will hold the carabiner in
place well

Once you've fished the bungee through the webbing go ahead and tie a barrel knot (half a double fisherman's) around one of your carabiners. This will hold the bungee in place as you begin to shorten the tethers to their proper length. The barrel knot is a good one to use because it will hold the carabiner in place and keep it from spinning or cross-loading.

BD tethers are 20" long

My tethers are 21" long

Begin to slide the webbing down onto the bungee cord. I used my older BD tethers as a template to get the proper length. You'll need to play around a bit here. The relaxed length of the BD tethers, from carabiner to swivel is about 19-20”, when stretched each strand is 45”. If I stretch my arms out, while holding one of the tether strands, it extends from one hand to the start of my other shoulder. I have ridiculously apelike arms, you could probably go a bit shorter.

After you've found the proper length you'll want to tie an overhand on a bight in the webbing/bungee approximately the size of a belay loop. This is where you'll attach the umbilicals to your harness. I chose not to tension this loop, keeping the webbing and bungee relaxed.

The non-elasticized attachment loop, where I girth hitch
to my harness

From the other side of the overhand bight knot you can tension the second strand and make sure it's the same length as your first strand. When I finished there was about 4-5 feet of bungee cord left over.

The nice thing about this little project is that the knots aren't permanent. Play around with the length of the tethers before you trim anything down or decide for certain that you like the configuration. Mine work great and the lack of a swivel has made no difference at all.
I look forward to testing them to get an actual strength rating sometime soon. I'll post that information when I get it.

Here are some other good links about homemade umbilical tethers:


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