Prop performance question

[kvam1]

Hello! I have been trying for a long time to find a propeller that works optimally for my boat and engine. Have a Nordic Oceancraft 22 DCO (weight approximantly 1400kg) with 2011 Mercury Verado l6 300hp. Now running Enertia eco 16x19. wot rpm of approx 6100 rpm (engine on max trim) and on a good day makes 48.2 gps knots. Slip about 7%. Good numbers so really happy with it. But also tried a Mirage Plus 14 3/4 X 21, then I only got 44 gps knots, but wot was 6200 rpm, and slip about 28%, so pretty bad numbers here. Anyone have an idea why or what the cause of this is? Does the diameter have that much to say on slip? And with regard to pitch, should I in theory increase the speed with higher pitch? Or am I completely confused here I know that bigger diameter lowers the rpm and vice versa and same with pitch. but I thought these numbers were a bit odd compared to each other

 

[dingbat]

Hello! I have been trying for a long time to find a propeller that works optimally for my boat and engine. Have a Nordic Oceancraft 22 DCO (weight approximantly 1400kg) with 2011 Mercury Verado l6 300hp. Now running Enertia eco 16x19. wot rpm of approx 6100 rpm (engine on max trim) and on a good day makes 48.2 gps knots. Slip about 7%. Good numbers so really happy with it. But also tried a Mirage Plus 14 3/4 X 21, then I only got 44 gps knots, but wot was 6200 rpm, and slip about 28%, so pretty bad numbers here. Anyone have an idea why or what the cause of this is? Does the diameter have that much to say on slip? And with regard to pitch, should I in theory increase the speed with higher pitch? Or am I completely confused here I know that bigger diameter lowers the rpm and vice versa and same with pitch. but I thought these numbers were a bit odd compared to each other

The "rules" only apply to props of the same design.

The Enertia is a pretty heavily cupped prop. All bets are off when comparing props of different designs.

What is a “cupped” propeller and what benefits does it offer?

Propeller cupping provides a lot of benefits with relatively small changes to blade form. Learn everything you need to know from the pros at Michigan Wheel.

www.miwheel.com

 

[kvam1]

The "rules" only apply to props of the same design.

The Enertia is a pretty heavily cupped prop. All bets are off when comparing props of different designs.

What is a “cupped” propeller and what benefits does it offer?

Propeller cupping provides a lot of benefits with relatively small changes to blade form. Learn everything you need to know from the pros at Michigan Wheel.

www.miwheel.com

got it thanks for replying! also have a mirage plus 15 1/4x19, it gives me 45-46 knots and 6500rpm. have not calculated slip on this one.