I just purchased a new prop for my 2016 Evinrude 150HP.  The prop I purchased is a OEM prop from Evinrude and the pitch is exactly what I had on it before.  I was just replacing the old one because it had some minor chips and scraps.  I installed the new one and took it out for the first time this year and at 800-900 rpm I’m getting a whistling/ringing noise and a small shutter.  I returned the prop and put a 2nd new prop on the motor and it is doing the same thing.  What in the world could this be? Before I had it winterized the boat last year it wasn’t making this noise.  Any help would be appreciated, Thanks in advance.