Help choosing prop for 18' cc with 90hp

[Gboats91]

I have an 18' center console with a 97 90hp johnson outboard. current prop is a 3 blade turning point 13.25x19. The motor only spins up to 4100rpm and about 29mph.

Im looking to try a 15p prop I believe, but im unsure if I can or should change diameter. Does anybody know what the max diameter I could fit on this motor is?

What are some common prop sizes that would work for me? Other manufacturer hubs that fit as well? I would prefer to find some cheaper used props with hubs already for testing purposes.

Also, does anybody know if I have a 13 or 15 spline shaft? I wont be back with the boat until the weekend and id like to source some props by then

 

[Gboats91]

97 Johnson 90 J90ELEUA shaft spline count

I have a 97 Johnson 90 J90ELEUA. I'm looking to change props. Does anybody know if the spline count is 13 or 15 on my motor? I won't be with the boat until the weekend and I would like to source a prop by then. I've seen both listed for this motor. Thanks

 

[GA_Boater]

Merged your 2 prop question threads.

 

[ezmobee]

I run a 14x17 on a 90HP on my 18'

 

[ahicks]

15" sounds small. The 17" would be a much more common size.

 

[Chris1956]

If your tach is accurate, the math says a 15"pitch prop is the right one. Hopefully your tach is accurate, and you have a normal load of fuel, people and gear in the boat when you read the tach.

When you pick the pitch of a prop, the diameter is usually chosen for you.

The prop manufacturer will know how many splines you have. Choose the correct hub for your new prop and enjoy.