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Old 10-24-2018, 10:54 AM
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ndutton ndutton is offline
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There are factors working against themselves here. I see the benefit of a large diameter prop for good flow exposure in an aperture mount but that means pitch must be reduced to avoid overloading the engine.

Only because they were produced in the thousands, the Catalina 30 may be a reasonable place to start. The factory fixed 2 blade was a 12X7RH which was a little much, produced max RPM of around 2100. Keeping your prop at 13" diameter for the reason mentioned, I suggest a 5" pitch may be really sweet. You might want to research the viability and cost of having a shop repitch your existing prop. For value comparison, Michigan wheel offers a 13X5RH 2 blade sailor prop for roughly $350.00.

Last year I swapped my 12X7 for a 10X8 that resulted in a significant improvement meaning the engine RPM is up in the power curve better and working a little easier.

edit:
I should have asked, direct drive or reduction gear? My comments apply to a direct drive engine.
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Neil
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others

Last edited by ndutton; 10-24-2018 at 07:55 PM.
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