Prop shaft noise

[Bill Conlyn]

2002 DeFever twin prop motor Yacht new to me. After haul/launch for anti fouling paint, both shafts have high pitched squeal up to about 1700 rpms engine speed. Did not have squeal prior to haulout. I mounted the shaft zincs approximately 3-4" foreword main struts and 3" aft of foreward struts. Location of zincs and painting is the only difference from before a-f paint and zinc replacement.
Is there any chance zincs are too close to bearings? I have always put zincs in this location on many boats.

[Rearsteer]

If the cutlass bearings were replaced, this could be it. If not put the zinks where they were and try it. Maybe pull them off and try it. Its a try and see kind of deal. If the boat is on the hard, don't turn the screws dry. This will make noise for sure. Old loose bearings won't make noise, but new ones will.

[Lepke]

The shaft seal packing could be dried out or was adjusted too tight. Not likely the zincs unless installed loose. If the shaft seal has a water line to it, make sure there is flow.
If this happens at low rpm. Try to come up with a stethoscope. If not, a rod/pencil between the ear and hull. Even a long screw driver works. At the dock, one engine at a time, at idle, listen thru the hull over the bearings and near the shaft seal. Try to determine exactly where the sound originates.

[David M]

Sometimes cutlass bearing squeal after a haulout even if not new. In my experience that eventually goes away. New ones almost always squeal for a while.

There should be a little distance between your shaft anodes and your cutlass bearings. Enough to get a little flow through the bearings. I gap mine about an inch.