You can not compare an air prop vs water prop in one medium. Obviously air will load up an air prop much more than a water prop and water will load up an air prop much more than a water prop. I asumed everyone understands this as we experience and feel it in everyday life.

I was basing my comment on the figures listed on the site with one specific motor. The purpose for larger 700 motors on planes is to spin a large air prop at low RPM (usually around 9000RPM or so) to produce maximum static thrust. In fast electric boats we don't need thrust over speed, so we use a smaller water prop with high pitch ratio's vs a large water prop with low pitch ratio's to achieve high RPM(>12 000RPM) in most cases and speed.

I'm not sure why or what you're having a hard time believing. I can place any water, any air prop on one specific motor and say either medium will load up the motor more. Completely depends on what application the motor is best suited for.

Ryan