Just to add to this...
GPM numbers are 100% irrelevant......Let me explain myself....
The amount of flow will dramatically increase and decrease with the amount of horsepower involved. That goes without saying.
But....
The GPM does not really come into play, nor is it easy to measure. The GPM does not move the boat forward. The thrust does...Measured in volume AND velocity, to get there you need pressure.
As the pressure goes up, it is accepted that the flow (GPM) can go down absorbing less horsepower (sounds backwards, but it isn't) .
So the true balance is when you can make peak thrust at peak HP, it is virtually impossible to get it right the first time no matter how hard you try....
Another really warped way to look at this is think about the material taking up space inside the pump....A common thought (which I totally agree with BTW) is that the thinner the impeller and stator vanes are, the more room there is for water, thus the more potential for improved performance.....The fuzzy math comes in when figuring how hard that water is to start and stop the rotational forces and generate axial thrust (think about it) the more water you flow, the more HP you eat up just changing it's direction.
I am from the old school train of thought....Make it smooth, skinny, and strong, then balance it to the gnats ass and it will do everything that is asked of it, but it still has to be cut to get the engine to spin it's desired RPM, otherwise it all goes out the window...
BTW, the term loads better is a farce, I use "stays loaded better", this is due to having less lift built into it, but a better shaped blade/vane...I have done some serious research on this, but never had the scratch to put it into play...
The determination of "faster" is a farce too....just because you can increase the exit velocity, does not mean more speed, sometimes quite the opposite, the volume has to back it up...Without balance, you got squat....
Remember, water is mass, bigger is not always better, but more is always more...
GT
