when using a prop slip calculator how do you account for a five blade and six blade prop ? second i been told that maximus props are not true pitch. what do i do to account for that ?

blades dont matter when CALCULATING prop slip, it just usually gets better the more blades you have.

prop slip is calculated by propshaft rpm/prop pitch/actual speed.

Many of the Mercury props are not the pitch marked. Nor is a lab finished prop the same pitch as a non lab finished prop. Sometimes the marked pitch and actual pitch can be 2-3" less than what's stamped on the prop.

The only way to know what the true pitch of the prop you are using, would be to have it measured.

It doesn't matter how many motors you have or how many blades the prop has. The slip calculation does not change.

As long as you are using the same model prop you can use the stamped pitch. If you change models and manufacturers then it's nice to have the proper pitch of the prop so you have an accurate slip number for each prop.

Matt