Vibration under power

[Mark Nooney]

We own a 1984 Hunter 31. When we are under power there is a vibration
(like a slapping or tapping) noise when the propeller is engaged. The sound seems to be localized in the area of the port quarter berth. I confirmed
that the sound only occurs when when the prop is spinning by revving the engine at dock. The engine is very smooth and is not producing the tapping sound.

So has anybody experienced this? I feel that it could be a couple of things
cutless bearing, shaft alignment, a barnacle on the shaft or prop, or a bent shaft.

What would be the best process for inspection and elimination of the issue?

Any input would be appreciated.
Thanks,
Mark

 

[Keith13315]

I had a vibration not tapping, same model and year boat as you have. I replaced the Cutless bearing and problem solved.
Keith

 

[Mark Nooney]

I take it that is a out of water experience or cn it be done in water?

 

[Jimmy Jenkins]

I just had same issue with my '78 30' with Perkins Perama engine. In my the case the rear engine mounts seem to have settled about 3/8ths of an inch. The tapping noise on my boat was between 800-1000 rpm and was caused by the prop shaft slapping against the bronze shaft log fitting. I raised the back of the motor about 3/8ths inch and everything now smooth and quiet.
Jimmy

 

[betzhunter]

I just had same issue with my '78 30' with Perkins Perama engine. In my the case the rear engine mounts seem to have settled about 3/8ths of an inch. The tapping noise on my boat was between 800-1000 rpm and was caused by the prop shaft slapping against the bronze shaft log fitting. I raised the back of the motor about 3/8ths inch and everything now smooth and quiet.
Jimmy

I agree with Jimmy, our Hunter 34 had a slapping noise when engaged, replaced the motor mounts noise gone.

 

[Keith13315]

Yes the cutless was done out of the water.

 

[gr8_2_av8]

I have the same issue but it runs much smoother in reverse. Any suggestions?

 

[Mark Nooney]

Jimmy,
How did you compesate for the shaft alignment?
Mark

 

[Jimmy Jenkins]

I haven't checked alignment yet. Ran it, in gear at the dock, and shaft log was cool and smooth. I'll check allignment before I do any serious motoring. If I need to a djust, will do it at that time.
Jimmy