Hello Richard,
It is good to meet you. Judging from your opening post you are well acquainted with the world of knots and very much understand the functionality of their operation. I am surprised that we have not seen you here before now.
Thank you! I'm really quite novice and wide-eyed at all the knowledge that is shared in a place like this.
The knot you bring to us and somewhat modestly call 'the Ossel knot but with a round turn', is, although only a small change , none the less a fundamental improvement which has eliminated the prime weakness of the Ossel (that it is prone to hold itself open at the key nipping point). Your enhancement functionally separates the gripping loop from the reversal bight and is for me an excellent example of a Nodeologist exercising his skills.
That separation is the main benefit of this knot, as I see it.
As I was experimenting with various structures in surgical tubing, any wrap or bight that passed directly over the standing part tended to get lifted away from the pole as it was loaded, owing to the elasticity of the material.
Take the clove hitch as an example. Imagine that the wrap that holds down the standing part and tail is pinned or glued to the standing part, right where they cross. They are stuck together. Now as you load the knot, the nip is pulled open, and the tail escapes.
This is the general action that I observed in surgical tubing - a combination of sticking and slipping. I have not been able to predict exactly where things stick and slip (and thus can't claim to fully understand it), but it seems that
often, wraps and bights that cross the standing part stick to the standing part as it is loaded. I think tubing may act grippier as it is stretched. In addition, the tail, having little tension on it, tends to spring, slide and/or pop right out of any nip that has been loosened.
Thus in many knots I tied, the standing part grips whatever is involved in a nip, opens it up, and the tail slides or wiggles out.
Even something like a bowline opens up. As the loop is loaded, the little half hitch opens right up, and the tail can slip right out.
From reading other people's feedback on this thread, it seems that some have had different experiences with surgical tubing. Others were able to make several knots to work that I had no success with. Maybe they are just better at fairing up and tightening the knots than I, or perhaps my single length of tubing is not representative of how tubing generally behaves. I'm not sure.
In any case, I came up with the proposed hitch in order to avoid this whole situation. No amount of loading or stretching will open up the nip - something that can be said of surprisingly few hitches that I examined.
This knot is definitely a keeper for me although I will probably use it with two small mods. First I will take the end under both strands of the round turn and second I will slip the end for ease of removal.
I like that - tucking under both passes of the round turn. It does seem to jam a little bit more. I would assume it can only improve the nip, as your experiments bore out.
Well done -- Have you thought of naming it?
I called it the "Fist Hitch" for the few months between discovering it and sharing it here, just because it looks to me like a fist. With the tail tucked under both strands of the round turn as you suggest, it looks even more like a fist.
In structure, it is obviously an Ossel with a round turn. But it doesn't act much like the Ossel, so I'm not sure if just calling it something like a "modified Ossel" is useful.