Yes, I asked myself the same question. I got some old surveys / documentation with my boat and reading them concluded that 19’’ max- prop has been originally installed by the factory. According to the surveys my lugging yanmar always suffered from oversized prop, even with 2.64 gear ratio.These all tie together and it's fairly clear to me that Freedom didn't understand the mathematics behind optimal prop sizing.
I also recall reading this article referred by Geoff in one of his posts , interestingly enough I noticed 2 kinds of vibrations in the shaft: one was kind of acute , constant after 1500 rpm, slightly increasing with rpms and the other one is king of “wobbly” after 2500 rpms which exactly coincided with 95 ft / sec blade tips speed of my orig. 19’’ prop. I can’t say for sure if that was cavitation .. but cutting prop to 17’’ diam. definetly helped
I also replaced the shaft / cutless bearing . I noticed that my shaft has been slightly worn on one side in area of contact with cutless bearing , probably from misbalance in max-prop. While checking around for the new shaft or repair my old shaft found again that price range is quite drastic .. from $400 to $1500 and seems to be not justified by any means.. eventually I found a place called ‘properpitch’ in Delaware. I do not have any affiliation with them. They seems to be quite knowledgeable and friendly , best price, prompt shipping . They have website , price list ..e.t.c. I can recommend them highly.Don't know my shaft dia. but need to replace it anyway - what is the shaft dia. on your F44 c/b?
That is what I found out as well. Mostly there are two types alloys for prop shafts on the market: alloy 22 and alloy 19 . A22 is almost twice more expensive with marginally better material properties. Talking with these guys I understood that for my particular 1 ¼ ‘’ shaft it is just no matter if it A22 or A19 while all the other shops simply insisted on A22 only..