prop size

[Frank]

does anyone know what the factory original prop size was on an 87 O'day 322 w/ a yanmar 2gmf20. ?

I just purchased this model and it came w/ a 3 blade prop that the previousowner put on. But I think its the wrong size or pitch because the boat only acheives about 3000 rpm max.

 

[TT]

Prop spec

Michigan Wheel have an on-line site for calculating the correct prop for your boat; you have to supply data abt. the boat ( beam, LWL, disp. etc ) and your engine & reduction gear, shaft size etc. & they'll give you a spec for one of their products. Other manufacturers probably provide the same service.
There are other reasons why your engine won't reach max. RPM : have you checked them out ? If you can do so, contacting the previous owner might be useful.

 

[Frank]

Thanks for the info TT

Thanks for the info found out that the prop may not be my problem after all. Engine will not rev up past 3000 rpm. even in nuetral. Am now suspecting back pressure. clogged exhaust. ?