Risk of Yosemite Bowline Knot

Yosemite Bowline knot is one of the most popular variant of Bowline knots used by climbers, notably for the harness tying-in point. However, there is a significant risk for the knot. Basically, a tiny bit of mistying, or even just a bit of wiggle during a course of a day, could cause a serious weakening of the strength of the knot. Here is my video to demonstrate the point — risk of Yosemite Bowline.

Here is the detailed background, followed by some discussion.

The Bowline knot [2018-06016: referring to Asheley's #1 hereafter, unless otherwise mentioned] used to be the most popular knot for climbers for a tying-in point to a harness. Nowadays, a majority of climbers use Figure-of-Eight instead, primarily because Fig-8 is far more foolproof than Bowline. However, there are still a considerable number of climbers who prefer to use Bowline knot or its variants. The Bowline knot (and its variants) have two advantages over Figure-of-Eight, that is, it is easier to untie, which is handy after the knot is heavily loaded (by falls), and is marginally quicker to tie. The major disadvantages are,

  1. Bowline can be undone accidentally, especially in a course of a long day,
  2. Bowline is especially vulnerable for cross-loading,
  3. Bowline is more easily mistied than Figure-of-Eight,
  4. Bowline is more difficult for partners to check (partly because many modern climbers don't know it in the first place),
  5. Bowline is significantly weaker than Figure-of-Eight (the experimental results vary a lot, but as a rule of thumb, Bowline seems to be 10-20% weaker than Figure-of-Eight), though this point is in a vast majority of cases in climbing not a serious concern,
  6. Bowline relies for a part of its strength on an additional stopper knot — in other words, if a stopper knot is not tied (or is undone, as it happens occasionally especially after a prolonged use), it is weaker, and the rope-end may travel through under a high load, even to the point of complete destruction of the knot.
  7. Bowline's stopper knot sits inside the main loop of the knot, and therefore, when it is used as the tie-in point to the harness, the stopper knot touches and catches a harness and/or other things around it all the time, and hence is more likely to get undone than the one with Figure-of-Eight (n.b., Figure-of-Eight knot, unlike Bowline, does not need a stopper knot in the first place for the purpose of extra strength).

Many modern climbers prefer one of its variants to the standard Bowline because they are supposed to address the disadvantages of the Bowline, especially the first one in the above-mentioned list. Note that they all are to some extent more awkward to dress (or set) the knot properly, and hence the caution in tying is still essential. The two most popular variants, apart from Left-hand Bowline (also called Cowboy Bowline, Dutch Marine Bowline, and Winter Bowline, Ashley's #1034½), among climbers are Double-Bowline (Ashley's #1013) and Yosemite Bowline.

Double Bowline has two loops instead of one to thread the (end of the) rope through. It is stronger, and is even easier to untie after the load, than the standard Bowline. However, I do not think it is less likely to come loose than the standard Bowline. Essentially, Double Bowline keeps all the basic principles (and hence cons) of the standard Bowline, but advances some of them. I have heard of a rumour Double-Bowline is pretty popular in Germany as the tie-in knot.

Yosemite Bowline has a follow through of the rope-end via the knot itself. Therefore, when the knot is tightened under a load, it constricts its own tail-end, and so reduces the risk of getting weakened due to lack of (or undone) stopper knot. Personally, I would still recommend you to tie a stopper knot, as I have witnessed the loosened Yosemite Bowline over a course of a day. Also, another advantage is the rope-end is at the outside of the knot and hence is less likely to catch a harness or body, whereas in the standard Bowline or Double Bowline, the rope end and the stopper knot near it touch and catch surrounding things like a harness all the time. Yosemite Bowline seems to be decently popular in the UK and (I guess) US among climbers.

A mention should be given to Edwards Bowline. Edwards Bowline basically adds an extra return to the rope-end to Yosemite Bowline. I have never heard of any quantitative assessment of the knot. However, given its complexity, I guess it is less likely to come undone than even Yosemite Bowline, whereas it is definitely more awkward and slower to tie. I doubt if Edwards Bowline is widely used in the UK, let alone outside (n.b., the name comes from the Cornish climbing legend, the Edwards).

In my blog post a year ago, Cross-loading on knots, I argued Bowline knots are vulnerable to cross-loading, and I also referred to a YouTube video "Yosemite Bowline not safe for climbing" (by "Yosemite Bowline" — seemingly the one-time account), which warns a potential danger of Yosemite Bowline (see also the extensive discussion in the UKC forum).

I have investigated the issue, and presented it in the video in this blog. My conclusion is as follows.

In short, the way Yosemite Bowline rethreads the rope-end in its knot is arguably undoing what Bowline is tied. If Yosemite Bowline is tied correctly and stays as such, there is no such risk. However, if Yosemite Bowline is tied in a (what I call) wrong-handed way, which is akin to the anti-Lapp Knot configuration, then the main Bowline part basically comes undone. The correct and wrong-handed ways are topologically identical, and so by definition they are interchangeable with an external force. In other words, even if Yosemite Bowline is tied correctly first, it can get loose and might transform itself to the wrong-handed configuration over a course of a day of activity by the wearer.

In fact, some argued it is still strong enough even tied wrong-handedly, referring to a single experiment presented in the UKC forum. I am not convinced (a single seemingly non-scientific experiment does not tell much anyway). More importantly, I know well, based on my own experience, even the well-set correct Yosemite Bowline can get loose during a course of a day. After all, Yosemite Bowline is, like any other Bowline variants, more awkward to dress well than the standard Bowline. That means, considering any stopper knots are not reliable for a long term, there is a small chance the rope end may come undone. Once the rope end comes undone, what will happen when loaded is obvious, as demonstrated near the end in my video.

I confess I have been using Yosemite Bowline knot as my harness tying point for well over a decade for indoor or summer single-pitch climbing. The primary reason is it can be untied much more easily than figure-of-eight after taking a fall(s). Falling is a norm especially indoor, and then the ease of untying is a significant advantage, as well as a speedy tying-in, which comes particularly handy in intensive indoor sessions like 4×4. Yosemite Bowline knot has served me well so far.

However, I do not use it during multi-pitch climbing or in winter, because I did notice its tendency to come loose over an extensive period of time, probably after the knot has been rubbed by something surrounding without me noticing. The fact does cast some doubt over its reliability.

I am a strong believer of Murphy's law: Anything that can go wrong will. The tying point of a harness is one of the most fundamental point of safety in climbing and is the most frequently tested one. If I tie in 20 times per week, I will tie in 1000 times per year, and 100,000 times per century (I won't live so long, but it is just for the sake of estimate). That means the acceptable probability of mistying the harness tying-point is smaller than 1 in 10 millions, or 0.00001%.

Now, I don't think Yosemite Bowline is trustable enough for me.



Bowline with Yosemite finish

Your video explaining the failure mode of the Bowline with 'Yosemite finish' is incorrect.

You have completely missed the key underlying issue!

The failure mode is induced by pulling on the tail before the core of the knot has been properly cinched tight.
It has nothing to do with the orientation of the tail as you claim... and your 'wrong-sided' Yosemite Bowline is in fact the correct orientation.

Summary of failure mode:
If you pull (yank) on the tail before the core of the knot is properly cinched tight - the tail will become 'displaced' to a position inside the nipping loop.

This failure mode can be induced in both orientations of the tail.

Mark Gommers

Actuially that is not the point…

masa's picture

Thank you for your comment, Mark. Unfortunately, I don't agree with your point against anti-Lapp Knot configuration – I would appreciate the reference to support your argument, if you could give one – and hence the discussion that follows.

Anyhow, the primary point of the article is that Bowline, including Yosemite Bowline, is much more insecure than Figure-of-Eight, especially in the course of a long day. I agree with you in one point; if it is properly cinched tight, it is OK, but only while that orientation is being kept. A critical problem is that there is no guarantee the condition holds in a course of a long day, and worse, one will forget checking about it, after tying one, on an odd day, sooner or later – it is just a matter of probability…


Quote from Masa:
"I would appreciate the reference to support your argument, if you could give one – and hence the discussion that follows."
Reply: I had given links to various papers on Bowlines and knots in general. Hve you read them yet?

Quote from Masa:
"Anyhow, the primary point of the article is that Bowline, including Yosemite Bowline, is much more insecure than Figure-of-Eight, especially in the course of a long day."
Reply: This statement is factually incorrect. When you use the word 'Bowline' - you need to be very clear as to which 'Bowline' you are actually referring to. There are actually dozens of different 'Bowlines'. In fact, there is a class of structures known as 'secure Bowlines'. Examples of secure Bowlines include: Scotts locked Bowline, EBSB Bowline and Lee's link Bowline; all of which are totally secure and stable.

You are publishing your article to the world via the internet and as such, you need to make sure that the information you convey is accurate (which it is not). Presumably, when you use the word 'Bowline' - you might in fact be referring to #1010 Common Bowline. But it is known that this type of Bowline is not secure - so why base your article on a structure that is already known to be insecure? This doesn't make any scientific sense. If you are trying to compare the #1047 Figure 8 eye knot against 'a' 'Bowline' - you need to compare it to one of the secure Bowlines. For example, if you want to compare particular off-road 4WD (SUV) vehicle against another vehicle, you need to select another 4WD (SUV). It would be invalid to compare against a conventional 2WD car. In effect, this is what you are doing.
Mark Gommers

Double Bowline

I have to add that the Double Bowline (usually called "Bowline on the Bight") is not unsafe and is one of two "official recommended" Knots for tying in in most of Europe. This is because there is NO possibility of getting loose by itself.
Also there is no "wrong side" to do it.
There are documented accidents of every other version of the Bowline (coming loose even if done correctly), but not one of the Double Bowline.

Double bowline isn't the same

Double bowline isn't the same as a bowline on a bight.

The german names "Doppelter Bulin" literal translation is double bowline but is in fact a bowline on a bight, which is one of two tie in knots recommended by the DAV.

Doppelter bulin - double bowline is a false friend...

See also Bowline on a bight wikipedia

Figure 8 versus 'Bowline'

Quote from Masa:
"Nowadays, a majority of climbers use Figure-of-Eight instead, primarily because Fig-8 is far more foolproof than Bowline."

Reply: This statement is factually incorrect - and represents only the opinion of Masa.
Are you aware that climbers also make mistakes tying the #1047 Figure 8 eye knot? Robert Chisnell reported an accident where a climber incorrectly a figure 8 into the harness. Authors seem to ignore certain facts and only choose to report on negative press about 'Bowlines' - presumably because they already have preconceived bias.

Your words 'Figure 8 is far more foolproof than knot XYZ' is a relative concept. As with all knots, practice is key. You are just as likely to make a mistake tying a figure 8 knot than with any other 'Bowline'. Climbers sometimes forget to feed the web belt back through manual locking harness buckles. In response, manufacturers offer self-locking type harness buckles to try to eliminate human error. Same goes with screw-gate carabiners - climbers often forget to lock them - so in response, manufacturers offer self-locking twist-lock style gates.
You could argue that harnesses with self-locking buckles are far more foolproof than harnesses with manual style buckles. But, are we really making a statement about human failings? Should we ban all harnesses with manual buckles that require the person to feed the belt material back through the buckle to lock it? Should we ban screw-gate carabiners?

Interesting post. One

Interesting post. One correction though... The "popular in Germany" bowline is the bowline on a bight (tied by rethreading),which is the only recommended variant by at least one of the German speaking Alpenverein for tieing in (confusingly called a Doppelter Bulin, hence being mixed up with the double bowline). I use this for single pitch sport only and has two advantages: stopper knot on the outside; if the knot did loosen fully, you still end up with a regular bowline with a very long tail. I'm happy with this in a sport context with frequent tieing and untieing.


I note that there are numerous errors in your article.
In the first instance, you prefix the word 'the' with 'Bowline' which in fact should be 'a' type of Bowline (not 'the' Bowline). There are many different types of Bowlines.
If you are going to tie-in with 'a' Bowline - you should select and use one of the inherently secure Bowlines.
The simple #1010 Bowline was never intended for life critical applications - it was discovered hundreds of years ago (likely by sailors) and used on the high seas.
An inherently secure knot is one that does not require any form of 'backup stopper knot' to lock-down the structure.
In other words, if you tie-in using one the inherently secure Bowlines, it is perfectly fine and does not require any form of backup stopper knot.
Inherently secure Bowlines include: EBSB Bowline, Scott's locked Bowline, Lee's link Bowline, Harry Butlers Yosemite Bowline.
Your article is misleading because it zeros in on one particular type of 'Bowline' (the Yosemite Bowline) - which is known to have have certain vulnerabilities. You then mislead the reader into thinking that all 'Bowlines' are somehow unsafe (based on the Yosemite Bowline).
Furthermore, the failure mode you describe in your video is incorrect. The real failure mode is triggered by premature yanking on the tail before the knot core has been properly set. This displaces the tail to a position outside of the nipping loop thus altering the knot structure.
I have written to you before about this - but you choose to ignore my advice.
Why do you ignore the facts?
Do you realize that you are circulating misinformation into the public domain? I think you have a responsibility to correct your content.
Mark Gommers

Incorrect Information

PSA: Incorrect Information

This information is incorrect. Please look over Mark Gommer's comment above on the subject as he a subject expert especially when it comes to knots.

Scotts Locked Bowline

The link you have provided to 'Scotts locked Bowline' and its alleged failure mode is an example of deliberately spreading disinformation into the public internet space.
There is no such failure mode - the original poster on the IGKT website is not a licenced test laboratory or an expert on knot testing. That person simply posted an experience that he was involved with - with a deliberately loosened knot and a deliberately induced snag.
The proposition tendered by that person could apply to any knot - to single out Scotts locked Bowline is non-sensical. For example, that person could also have tied a #1047 Figure 8 knot in a very loose dressing state. Any tie-in knot that is loose - has the potential to fail (obviously).
To commence climbing with a loose tie-in knot strongly implies recklessness and/or incompetence. A competent diligent climber would undertake a partner check BEFORE commencing climbing - to check things such as their tie-in knot. Checking your tie-in knot is a mission critical action because your life depends on it!
You should remove your link to the alleged failure mode of Scotts locked Bowline because it is false.
Scotts locked Bowline is inherently secure and is fit for purpose in climbing applications.

Bowlines (vs. Fig.8(s)) discussion

Before this runs into another venting verbosity from u-no-hoo,
let me less emphatically remark that there are many good ways to tie in, and some of these use variations of the bowline. Of which some might incorporate a fig.8 structure, for security measures. Try this : with the Yosemite Bowline, let the to-be-further-tucked (out through collar) tail *swing wide* so that it crosses the main line, AND THEN instead of tucking it on out through the collar, bring it back sharply through the main "nipping" loop; in this way, this further-tucked tail binds against the main line, helping to keep it snug, and it of course is wrapping around the tail. (A similar tucking is recommended (by me) with that DAV-recommended tie-in.)


One HELLuva lot of bowline confusion would be spared were the proper FRONT side of the knot shown instead of --as has been done since the dark ages-- the back side :: show the side where the main line crosses itself in making that key/bowline-defining loop!! (Google images of "sheet bend", which is bowline-like : that is usually presented from the helpful side; but bowline, almost never.)

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