Hard Is Easy
2 HN recommenders · recommended in 3 months, 2021–2022
17:37 · 626K views · Aug 29, 2020
Hard Is Easy runs experiments to show that a correctly tied figure 8 knot is not hard to untie after loading. He shows how two knots that look similar can behave differently depending on how they are dressed.
Cited in climbing knot threads to counter the claim that figure 8s jam, by showing the correct tying method.
4 comments from Hacker News
This is a great video. A summary for those who don't want to wade through it: The main message is that if the knot is slightly loose, or messy, the strands pinch unevenly in a fall, and it can be really hard to untie (depending on the rope). Most of the video is experiments to show that. The knot only had to be slightly loose to cause problems. The part that surprised me is that there are two different ways to tie the knot that basically look the same. They only differ in which of the two outgoing strands is the one that's loaded. They're both perfectly safe, but one can be a lot harder to untie than the other after a fall. I actually find it hard to end up with the "wrong" version of the knot, but I might just be lucky with what my muscle memory has latched on to. I certainly wasn't taught to watch out for the difference. The difference between the two knots is shown at 13m 24s: this video His demo of one way to get the knot the right way around is at 7m 41s of another long video: [LINK]
Apparently there is a wrong way of tying a figure 8, that leads to a version that is much harder to untie. Personally I've never had issues untying a figure 8, so it might just be that my default way of tying it happened to be the correct way. It's described in this video: this video Skip to 13:20 for the interesting part.
A few adjustments from a rock climber and camper here: 1. When joining identical ropes, the reef knot is adequate for any situation where the sheet bend is adequate. The rolling over and jamming under load described above usually happens when joining different ropes. Deconstructed, the sheet bend consists of a loop in one rope and a bight in the other: you want the loop to be in the 1) thinner or 2) higher-friction of the two cords (in that order of priority). There doesn't seem to be any downside to using the sheet bend over the reef knot in identical ropes (besides perhaps complexity) so I tend to agree with the implication above that the sheet bend is the superior knot. Neither knot is recommended for life support applications. 2. The bowline coming undone under non-continuous load is very real and has resulted in some climber deaths. However, I think the half hitch addition suffers from the same issue--it merely takes longer to come undone this way. A more reliable finishing method is to tie a double overhand in the tail either around the loop (see [1]) or around the standing end (this is common and effective but not my preference for purely aesthetic reasons). The double overhand binds under load, but load will be intercepted by the bowline's turn and the overhand should never come under load. A double bowline will extend the life of your rope by widening the bend that comes under pressure, but isn't appreciably safer in adequately strong ropes. 3. The clove hitch coming
Figure 8 knot is not that hard to untie after a fall, you just have to tie it in a particular way [1]. [1] this video