Impellers, Wear rings & Tools

SOLAS lists a reference guide for your selection of the best possible impellers:

a. If the RPM is too high, then you need to go for a higher pitch.
b. A lower pitch angle of the impeller should be suggested for heavier boat.
c. A lower pitch angle of the impeller is suggested in high altitude area, such as mountains.
d. A higher pitch angle of the impeller is suggested in cold weather areas.
e. A higher pitch angle of the impeller is suggested for top speed performance preference.