in theory

[Bill Van Steenwyk]

All other things being equal as you state, what if there was damage of some type in the intake, other internals, or thrust section of the impeller housing that was disturbing the water flow and consequently the speed/efficiency of the water column being expelled. I would think that the interior housings (made of aluminum?) could be very much affected by sand, dirt or other foreign material sucked into the housing along with the intake water, thereby eroding the interior of the housing, the impeller, and otherwise affecting the outflow of the pump, reducing velocity and decreasing speed.

Possible?, I don't know for sure, but it sounds plausible if everything else is exactly equal as has been previously mentioned, especially about the drag of water over a surface.

[50hptiller]

do yall do anything to reduce the amount of aireated (caint spell) water coming off the back of the boat? it seems to me if you could reduce that then you could raise the motor to just before the intake breaks the surface and reduce pump housing drag...also what about a "skid plate" from the back side of the intake to the underside of the pump all the way to the back of the output? do yall run a trim system on the back of the pump?..... dunno just a thought.... i never seen one up close of got to play with one but i sure been looking at em