prop pitch

[blackiron]

90 h.p yamaha 1985 what would be the correct pitch for a new prop.21ft boat.thanks

[Scout175]

I have a 1999 C90 and I am using a 13X19 for my 17.5 foot Scout based on the recommendations from the factory. I think it may be over pitched but it brought the RPMs down from 4500 to 4000 at 32 mph.