Thank you very much. the article indicates that, while a properly tied timber hitch is adequately strong, it is not the very strongest knot. Somewhat surprisingly, they did not test the unknotted breaking strength of the ropes they used, and hence did not provide a measure of "efficiency," the percentage decrease in strength that occurs when the rope is knotted.

The article does indicate the importance of a properly tied and dressed knot and that there is a degree of randomness in any lash up,so don't push to the very limit of these numbers!

I would say that probably the very strongest anchor know would be a rewoven figure eight, properly tied and dressed,closely followed by the bowline and its variants. There are more variations of the bowline that there are cross ties on the railroad or stars in the sky.
_________________________
Geezer in Chief