What knot tightens under pressure and is difficult to untie under tension?

Question

If I made a noose with this knot and lifted a heavy object by putting it inside the noose / knot:

1. the knot should slip and hold the object tightly automatically
2. it should be difficult to untie the knot when it is under pressure due to a heavy object.

Is slip knot good for this? Which other knot works well?

Answer 1

Slip knot will work fine, but if you want a more secure knot then I would probably recommend the Poachers knot. It's essentially a slip knot tied with a double overhand instead of a single.

Answer 2

Despite not being a knot, I think a bale sling meets your requirements. There is little resistance on the hitch meaning it will cinch tight pretty easily and it is difficult to release while loaded. You also might want to look at a barrel hitch (again not a knot). It doesn't cinch tight in the same way and one can remove the object easily even when under load, but the design of the hitch is such that the object is unlikely to simply fall out.

Answer 3

My goto is the buntline hitch. I prefer the slipped variety as the non-slipped version is very difficult to untie after its been heavily loaded. The slipped version works very well and makes everything fall apart with a small tug of the tail.