Frawg - your results are the same as mine using the constrictor arrangement that ZA206 originated. I went from an 8" bury which slipped to a 24" bury which didn't slip. I noticed as you have, that with the 24" bury only a fraction of the bury near the end at which the force is applied was effective. The opposite end was usually loose and ineffective.

I then abandoned this method and adopted carboy's method which applies force to both ends of the constrictor. This makes the full length of the constrictor fully effective and a much shorter length can be used and no back-up half-hitches or any other knot is needed.

That is also why eye splices with a fully buried tail are so effective and are rated at between 97% and 100% of the rated rope strength. With the eye splice and buried tail, the force is applied to both ends of the bury.

Quote Originally Posted by Frawg View Post
Okay, I had my coffee and made another UCR. It actually held without slipping, even with me bouncing a bit in the hammock.

What differed this time was that I made the bury 18" long, a bit under 8 fids for the 7/64 AmSteel I'm using.

So, an 8" bury failed and an 18" bury succeeded. I'll experiment with bury length to find the tipping point.

The idea I alluded to in my previous post was to put the slippery half hitch at the tailing end of the bury, rather than as a stopper at the head end. Though it seems counter-intuitive, I think it ensures that both ends of the bury are initially under tension which, in turn, induces the compression whereby the bury grips the inner line.

It may also be that part of this morning's success with the 18" bury was to 'milk' the length of the bury prior to loading the line, making sure that the bury and the enclosed line made good contact so the constrictor could bite.

There is obviously some threshold length for the bury. I believe that a short bury could still be made to hold by using a hitch at its tail -- slippery half hitch, rolling hitch, sailor's gripping hitch, etc, etc. I'm not sure what the active mechanism is. Perhaps the tailing hitch merely needs to compensate for the friction deficit of the short bury. I lean, though, toward my initial idea -- that the hitch ensures initial tension at both ends of the bury.

Hope that makes sense, but I am open to correction and education.