Just was doing some reading up and came across this for newbies

How to Select Impellers


  • Impeller selection used to be based on levels of engine modification. While sheer power remains a guide, other parameters have been found to be equally important. Take into account how and where the craft will be used as well as its physical characteristics.
  • 1. The more horsepower a watercraft has, the higher the impeller's pitch angle can be.
  • 2. If rpm tend to run too high, a higher pitch angle is recommended.
  • 3. Higher pitch angles are recommended for use in cold climates.
  • 4. Higher pitch angles are recommended for top-speed performance but will lower acceleration.
  • 5. Lower pitch angles are recommended for heavier boats.
  • 6. Lower pitch angles are recommended for higher altitudes.
  • 7. Lower pitch angles are recommended for towing.
  • 8. Lower pitch angles are recommended for acceleration performance, but will lower top end.