[C320-list] High pitch whining (singing) noise from shaft above 2800

[Rick Sulewski]

Danny, 
Several years after purchasing our 320 I cleaned up the two bladed prop with some sandpaper before launch and I had apparently induced harmonic prop whine or singing. After filing a flat edge on each blade the whine ceased.
If you closely inspect a new or refurbished prop you may note a flat edge at the end of each blade (90 degrees flat edge vs. the prop face or blade). I was under the impression when I cleaned the prop that making the leading edges of the prop sharper was desirable.....wrong idea because the sharp edge created the harmonic prop whine!  Now, whenever I replace the cutlass bearing (because I had  to remove the prop at that time) I send the prop into the shop to be trued and balanced. Over several hundred hours of motoring increases the chances of at least one or more blades striking any number of objects that could also contribute to a vibration and even prop whine over time.
Rick Sulewski
95' 320 hull #277

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of danny jensen
Sent: Monday, June 19, 2017 4:52 PM
To: C320-List at Catalina320.com
Subject: [C320-list] High pitch whining (singing) noise from shaft above 2800

I have hull 972 with new shaft,strut  and stuffing box about 4 years ago.
Cutlass was replaced about 5 years ago.

When I run above 2800 the singing starts.  Then at 3100 it stops.

I've got GFO standard packing and the noise is not coming from stuffing box. Only happens in gear. It Didin't sound like if was from transmission.

If the prop hits a chunk of kelp, this fixes the problem for a while and I don't hear any singing.

Any clues?

Danny
#972