Hi Rosco,
A well wheel - could you describe what this is please? I suspect I know, but I would just as soon not assume. Does it have a rim with any kind of a groove in it such as a sheave would have? As for the load the knot/bend/hitch/splice can carry, that depends on the strength of the line, the ability of the tyer and, of course, the type of knot/bend/hitch/splice. If the knot/bend/hitch/splice reduces the strength of the line by 50% say, then the strength of the line has to be at least 200 pounds SWL or at least 1000 # BS if the line is brand new. Some knots or bends may be stronger than others (here I assume that "strength" refers to ultimate tensile strength at breaking) and some splices may be better suited than others. Question 2 - what is a "tail" , why is it there, how does it fit into the well wheel loop, what is a well wheel loop, and does the sheet of plywood have dimensions (length, width, thickness, density) to it, or even any hole in it? Does the sheet of plywood exist as a single sheet or is it one of several pieces? Is it subject to windage? Lastly, how thick is the line and is it made of a specific material?
Yeah, questions, questions - still, it never hurts to clarify!
Lindsey