What prop should I be using, it’s an 18ft searay with 185hp, originally came with a 14.25” x 17 pitch. Just bought a 15”x17 pitch and I’m getting a humming noise at 1200 rpm, with smaller prop I could go 40 and be at 4800 rpms, now that I have the 15” I can only go 32 at 4800rpms.
