Whisteling Sound Between 2800-3200 RPMs

[efiste]

When running my 1987 Catalina 34 Universal M-25XP diesel at about 80-90% of full power (2800-3200 RPMs), I hear a "whistling" coming from underneath the stern cockpit seat. There is no noticeable change in vibration. It does not sound like it is in the locker (although it could be) and it definitely does not sound like it is from the engine compartment. The sound does not occur at any other RPMs (above or below) and occurs on queue every time when within the RPM range. While under sail, I can also replicate the sound when reaching a certain speed. When this occurs, if I "lock" the prop (put the engine in gear), the sound stops. It seems that it must be from either the shaft's cutlass bearing or stuffing box.

1) Thoughts on which?
2) What advise should I heed: Can I operate the season with this situation? What should be avoided?

The boat is now wet without any easy access to have her hauled back out.

Thanks as always,
Eric
1987 Catalina 34 (Hull # 358) - Windbreaker

[shogan50]

It sounds like your prop may singing. A friend just modified the trailing edge of his prop to solve the problem. http://www.hydrocompinc.com/knowledg...Propellers.pdf