开云体育

Let do some math.

2500 Max RPM divided by 3.21 = 778.8 RPM at the Prop

8 knots is approx = 9 MPH

9 MPH = 47,520 feet per hour

47,520 feet per hour = 792 ft per minute

792 ft per minute = 778.8 rotations per minute = 1.02 ft per rotation

1.02 ft per rotation is approx = 12 inches per rotation?

12 inches per rotation gives you the minimum pitch assuming that all the rotation of the prop resulted in forward motion of the boat.

Looking at the Easy Prop Table, 24 deg, 11.8" is the most they recommend.

You could go past the recommended to 30 deg, but that is a lot of pitch and at that pitch you may exceed the torque rating of the motor.

?

Can you change the reduction gears?

Depending on what you like to achieve probably? It sounds pretty good to me already. If it was me I would go for as little pitch as possible to try to make the propeller as efficient as possible. But I would be more interested in power to drive into wind and/or waves than try to get the highest speed possible. Would be really interesting to see what it will do with efficiency when you increase the pitch.?