Just to prove I have no
idea what I am talking about...........but what the hell.
Would the thrust of a jet will reduce as it gets lower in the water because the "water pressure" (hydrostatic head?) increases with depth? This will subtract from the nozzle pressure. I think it will would have to be quite deep for noticeable reduction.
Cant try a hose at the mo', because it has gone all stiff and the top of the bucket has some sort of hard film on it.
Props sort of cut a thread through the water (hence the term "screw") with the aid of the pressure differential across the blade.
Bigger diameter = more thrust (bigger surface area for Newton's theory to play with), and bigger pitch = more speed (distance per rev).
I am thinking about wood screws here
. A No. 12 will pull something up good and tight but makes the wrist ache. A No. 4 will zip in nice and quick, but if you tighten it too much it will loose grip.
If you skip this reply, I don't blame you.