14

It seems that the majority of professional arborists favor friction hitches that are tied with a free cord rather than a loop:

This is often tied using an eye to eye hitch cord like this:

enter image description here

This is a Blake's hitch:

Blake's hitch

One can also tie an asymmetrical Prusik without access to the end of the rope using one of these cords. As far as I know none of these are popular among rock climbers.

Some people do not carry any dedicated Prusik loops, relying only on runners, but I have seen enough climbers that do. For those that are carrying Prusik loops why not a single or double eye hitch cord?

I find ascending a rope with a Purcell and a waist Prusik challenging enough. If one of these arborist's hitches works just a bit better why not consider it?

I think it is valuable to know that one can tie a friction hitch using the end of the rope itself (Blake's) even if this wouldn't be a typical application; it's another tool in the toolbox.

Am I forgetting other critical uses for a Prusik loop that an eyed hitch cord cannot perform? Are there other practical reasons to choose a closed Prusik loop over these hitches, or is just a matter of different culture and experience? (Splicing eyes is not a typical climber skill from what I gather.)

  • Do those eyes come pre-made or do arborists make them themselves? To me that's more of a hassle, and I don't trust myself to make one – Chris Mendez Feb 4 '16 at 0:37
  • @Chris You can buy them pre-made but bulk cord of the right type can be spliced as well if one has the tools and know-how. – Mr.Wizard Feb 4 '16 at 0:42
12

The main reasons is simplicity and habituation:
A prusik made from a loop is easily taught and controlled. This is a point that many experienced climber forget about often: When people start they may struggle on the basic knots. So for the first thing to learn a simplicity is more important than functionality. And the prusik is a long established and reliable knot. Safety is good too: Just check the knot before use and add a turn if more friction required.

Why do many people stick with it?
The simplicity is reason again, but the other is simply habituation: It is much easier to simply stick with what you learned, it feels "comfortable". Another important aspect is interoperability: You (almost always) climb with a partner and should control each other, so all the knots must be known to both climbers. So you have to employ the smallest common denominator of knots, which is usually the more basic knots.

Other uses are in mountaineering when on glaciers you use a prusik on the cord and hold the sling with your hand. This can then immediately be used for a preliminary anchor. For climbing I do not see any other uses.

Why not the arbory knots you showed above?
I think this is only for historical reasons: Different knots evolved in these two areas that had probably not significant enough overlap to merge. I can do a prusik without a pretied loop (you just need to secure the free end with e.g. a double fishermans). I learned this for a variation of a pulley in crevasse rescue, but it is simply more complicated: You have to do knots on both ends of the cord while in a loop you can just clip into. Here your point of cords with eyes in them comes into play: I simply never saw such a thing in climbing and as you stated I have no idea about splicing. So I guess definitely a culture thing (a friend of mine is arborist and avid climber, never saw one on him either).

Still many people I climb with do use other friction knots. Some do not carry a pre-tied loop for prusiks with the argument that it can only be used for this single purpose and is thus ineffective. They use slings instead. I often use a longer pretied loop to do a knot we call "Englaender-Prusik" (literally: Englishman's Prusik, heard of it as French Prusik too :P, correctly: autoblock, thanks Mr.Wizard) for which you simply wind the cord some times around the rope and attach both ends to a locking biner: Easier and you cannot drop the cord as one end can always stay in the biner.

  • 1
    Thanks for your answer. A few more questions if you please: (1) Would you ask your arborist friend what he uses and why? (fixed tail, split tail, whatever.) (2) Do you have a reference for the use of a single ended Prusik as you describe? I cannot think of a reason for it to fail but at the same time I like to know that things are well tested before using them myself. (3) The "Englaender-Prusik" sounds like what I know as an autoblock; is it? (4) What do you use as a personal anchor? – Mr.Wizard Feb 1 '16 at 13:27
  • 1
    @Mr.Wizard: (1) will do. (2) Its from the book in German "Bergsport Sommer", K. Winkler, H.P. Brehm, J. Walter (SAC Verlag) but you can find examples searching for "end of the rope prusik" (although sometimes with to me quite strange ways to secure the loose strand). (3) Yes it is, thanks for pointing me toward the correct term. (4) I am not sure I understand right: When climbing: The rope (clove hitched to belay) and abseiling a sling (knot in the middle under which the tuber goes as breaking device). Or did you want to know something else? – imsodin Feb 1 '16 at 15:22
  • Re: (4) No, that is what I wanted. A lot of experienced climbers use the rope itself as a personal anchor but I was taught the use of a Purcell because it also has use in rope ascension / self-rescue. – Mr.Wizard Feb 2 '16 at 22:21
10

A climber and aborist should be superbly proficient in a knot or technique before relying on it. An Arborist will spend 100's of hours a year climbing - much more than average climbers, and has more time to become proficient in complex techniques, and uses them enough the advantages are worth the effort. Most climbers on the other hand will climb a few hours a week at most and will rarely use, and therefore loose proficiency in many knots and techniques that in theory are better if done well. i.e. Doing the 'second (or third) best' way well trumps doing the best way poorly.

Therefore, climbers should initially learn and use one way, ideally that can be used in many situations before thinking about alternates. Once experienced is gained, some look for better ways to do things they do often, but rarely worry about optimising things the don't do much - the reward for the effort (initial and ongoing) is not worth it.

  • 4
    There's also another component that does not allow for a fast change in paradigms: interoperability. When climbing you typically climb with different partners and as a responsible climber you also check other climbers' setups and knots. Now nearly every climber can do an optical check of a figure-9 knot, with a Bulin it gets more complicated and you won't find many who are familiar enough with a double Bulin to tell right away if it was tied correctly. So in doubt you step down to the simplest solution you can expect everybody to be able to work with. – Benedikt Bauer Feb 2 '16 at 14:39
  • @Benedik That's an excellent point. I don't think I've ever seen a figure-9 in the wild however and I am not confident I could check one on sight. Bulin is the same as bowline I am assuming. – Mr.Wizard Feb 2 '16 at 22:24
  • @Mr.Wizard Yes, Bulin=Bowline, and the figure-9 should have been a figure-8 of course... – Benedikt Bauer Feb 4 '16 at 8:27
  • @Benedikt A just-in-case FYI: there is a "figure 9" knot that is supposed to be easy to untie; I've just never actually seen anybody use one. – Mr.Wizard Feb 4 '16 at 8:37
5

Something that occurred to me after asking is that a Prusik is bidirectional, whereas generally the arborist's knots are unidirectional.

I believe the unidirectional knots are easier to both slide up and release, making them superior in a dedicated climbing rig, but their application is limited as well. Following both existing answers emphasizing simplicity and the value of learning one good knot and knowing it on sight it would be poor to teach a unidirectional friction hitch as foundational.

With a unidirectional hitch there is also the small but significant risk of tying it backward and having the knot fail to hold. While this should not happen in a simple ascension system, and it should be apparent soon enough if the knot is not holding, if the hitch is part of a safety system it could potentially be a big problem. Consider for example using the setup in the following diagram taken from What to do when you run out of rope on a sports climb? Is it immediately and unambiguously apparent which way to attach a unidirectional hitch in this application?

Even if it were will one be practiced in tying it in that orientation?

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.