harmonics

[obenton]

I have a 1988 californian. Had a slight vibration after touching a muddy bottom. The marina went overboard - I asked them to check the running gear and check the alignment. The props were sent to a local prop shop. I drove the boat back to our marina and immediately heard a squeal from the port side - very loud at 1000rpm then quiet until 1800 and then gone. Felt the shafts underway and no vibration. The cutlass bearings are a year old. They told me it was a "harmonic" and would disappear. I read this can occur due to differences in the trailing edges of the props. The screech is still there. I would love some advice, OB

 

[Edelweiss]

I had something similar and it turned out to be the shaft packing, which hadn't been adjusted or touched in a year? But for one reason or another it started squealing on one shaft when we left the marina.

The packing nut and shaft weren't even hot, but loosening the nut made it go away. Readjusted the nut and hasn't happened since.