Squeal from drive line

[Brahmany]

Hi all, Our Catalina has developed a squeal somewhere in the drive line.
The noise is only at certain RPM or sailing in neutral at about 4 to 5 Kn. The Squeal starts under power at 1100 rpm fades out at 1300 and comes back at 2200 to 2500 RPM. (double revs) Cutlass bearing replaced a few months ago and have just replaced the stuffing box packing with GFO still no change. Any ideas. Cheers

[model 10]

2 blade propeller?

[Brahmany]

3 blade Guy. Also uncoupled the shaft from the transmission and ran engine through the rev range with no noise and of course no load. Changed tranny oil. The old oil was spotless with no metal residue. A mate did a dive and reported that the cutlass hadn't moved, the prop was on tight and the anode was secure. Used the screwdriver to ear and cant isolate the noise. Perhaps I might get a stethoscope. Cheers.

[model 10]

So the double frequency thing seems like it would rule out a 3 blade propeller problem. How about your strut? Catalina struts sometimes get wonky, or a bent shaft?. Back off the packing nut a lot, and then run it.

[De.windhoos]

This is weird! See my post Noisy shaft when sailing after installing new engine and new seal - Cruisers & Sailing Forums
Also a Catalina..