what cutting a props diameter down does? Hopefully in a simple answer.

Well, by reducing diameter you will increase RPM...but there is a fine line as it is directly correlated to thrust.

Julie

I can give a big answer but it will take awhile.

It does all kinds of things besides raise rpm.

Boay attitude, acceleration, slip.

Diameter adjustments affect certain boats more than others. A 1/2 inch will affect F1 tunnel hull alot more than a current model 42 Fountain.