Improved Rescue Spider (with Bowline on a Bight)

I've been practicing some self-rescue techniques and working my way through Tyson and Loomis' book Climbing Self Rescue, and I think I've come up with a small but useful improvement on the standard rescue spider.

For those who don't already know, a rescue spider is built from a loop of cordalette and used to rig a tandem rappel that safely and quickly brings two climbers, one of whom might be injured or incapacitated, down a multi-pitch rap. The idea is that at each rappel station, both climbers stay connected to the spider and the tail of the spider is used to clip in with a Munter-Mule-Overhand. Once the rope is pulled, you then set up your rappel using the spider as an extension, then release the MMO to get your weight off the anchor and start rapping.

The method I was taught is to make tie a figure-8 on a bight in your cord loop, which leave you with one long single loop (for the rescuer) and one shorter double loop (for the victim). Here's what that setup looks like, with the MMO tied and the rappel device attached:

Tyson and Loomis note one drawback to this setup: "Its only drawback is that its tether lengths are fixed. It is not as easy as a Purcell to adjust your position relative to your patient once connected." There's another, which is that it takes a decent length of cord to build, because the figure-8 has four strands going through it and the shorter loop ends up doubled. They recommend 20 feet.

Replacing the figure-8 on a bight with a Bowline on a Bight solves both of these problems. The bowline on a bight creates two loops naturally, and as anyone who's used this knot to build an anchor with the climbing rope knows, the length of each loop is adjustable. This makes it much easier to position your patient comfortably in front of you so you're able to support her properly during the rappel. Like any bowline, it's also easier to untie after loading.

Here's what it looks like:



And a close-up, sans rappel device:



Besides allowing for easier adjustment of the tether lengths, this knot takes up a LOT less cordage. I tied these in my rescue cordalette, an 18' length of 6mm cord, using Tyson and Loomis's recommendation of a 1.5' loop for the rescuer and a 1' loop for the victim. The figure-8 version loops took up 64" of doubled cord. Subtract those from Tyson and Loomis's recommendation of a 20' cordalette (a 120" loop) and you get a recommended 56" tail to tie the MMO in.

The bowline on a bight version took up only 38" of doubled cord. That means to get the recommended 56" tail, you only need a 94" loop, or about a 15.5' cordalette. In a real pinch, you could probably get away with 12', which would be impossible with the figure-8 method.

Thoughts? The only disadvantage I can think of is that not all climbers know how to tie a bowline on a bight. That's not an insignificant problem—self-rescue should use well-practiced skills. But for climbers that know the knot well, I think the BOB is a clear winner here. It's worth noting that since there's no tail to work loose, the BOB doesn't share the instability of the regular bowline.

I was just working through rescue spiders today and I like that you are thinking outside of the box. In a rescue situation our level of risk acceptance might have to increase with our available materials but one could argue that one loop of 6mm cord is not redundant or safe enough. When the rescue spider is tied with the figure 8, one side is doubled; you could tie the other end with extra cordage and then tie a redundant knot on that side as well but that makes the spider even more complicated and eats up a ton of cordage.

I personally feel that making a rescue spider with a cordelette is somewhat complicated and eats up a valuable piece of material; have you tried using the end of the rope with one end tied to the victim (either a hard knot or fig 8 on a bight and a locker), threaded through a locker on the anchor, then mmo to the rescuer. You should always have access to one end of the rope and this leaves your cord open for whatever you need. In this situation you would need to use a PAS or sewn sling tether to set up your tandem rappels.

I have never been involved in a real rescue situation but in live practice scenarios, using the end of the rope seemed far more simple and faster.

Thanks for the feedback. I'll have to try your method with the rope. My first impression is that the spider would be a bit quicker and cleaner, but maybe not. I do find it's less of a hassle to rappel with the rope ends hanging below me rather than staying tied in, but that's probably just personal preference.

Personally, I have no problem rapping on a loop of 6mm cord. The stuff I have (PMI) is rated to 7.5 kN, so 15 kN doubled. It wouldn't be my first choice on an anchor that could take a factor 2 fall, but the forces involved in rappelling are pretty low. Redundancy is a higher concern IMO, so I might start to clove hitch the spider to the lockers. That way if one strand gets cut the other will hold. It might also keep them from cross-loading.

Of course, if the strength rating still makes you uncomfortable, you could use a 7mm cordalette.

As far as the ropes hanging below you: as soon as you release the mmo and weight your tandem rappel, you simply unclip the fig 8 on a bight from the victim, retrieve the locker from the anchor, and toss the rope: added bonus you already have a safety knot in the end of your rope.

I personally also have no issue with the 6mm but I think it would all depend on the situation and making approrpriate decisions accordingly.

Many of the self-rescue books out there provide invaluable information, but often involve very complicated and unorthodox techniques that can be duplicated using much easier means. Trying to remember a complicated system that requires extra gear and dozens of steps is not something you want to rely on in an emergency (unless you're SAR and you practice this stuff for a living).

Having been in an actual emergency before, I can tell you the most important thing you need to be concerned with is simplicity and speed. What is the fastest technique that can safely accomplish the mission? Often it's the most simplest one.

I am a big fan of figuring out how to use gear that's part of my standard rack to accomplish the task at hand. I dont like bringing specialized equipment that very likely will not be used, not if I can complete the task with gear I have. What is one piece of gear almost everyone carries on them on multi-pitch routes? Slings. Normally in the form of over the shoulder or in a trad draw. What else? A personal tether of some sort. I would use that gear to extend the rap and just do a standard, extended ATC rap. You can use the slings to step in to unweight the gear if the belay is hanging.

^+1 for 20kn.

Thought about using the end of the rope, in a 'rescue' you want to keep the rope free from the system that you and the victim are on. It's worth the dedication of a cordallette for the gain in flexibility. For this reason it's a good idea to always carry some dedicated rescue cord on a big locker that lives on your harness

Think you might be overthinking it. Tying a rescue spider takes a few seconds once you're proficient at it