Shaft or Prop vibratiion

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Oct 19, 2011
181
Hunter 42 Passage San Diego, CA
You all are my "go to" folks when I run into something I am not familiar with....so here goes with another one.

42 Hunter passage, Yanmar engine, Autostream prop, standard packing gland. I have experienced a vibration when under power for over a year. At lower RPM's it is not significant but when I get to 2200-2400 RPM it about shakes the aft cabin and swim deck off the boat. To the point I am fearful of greater damage if it goes unrepaired. I recently had an engine guy go with me on a sea trial. 2200-2400 RPM shook us to pieces. we took it from there up to almost 4000 RPM and the vibration was almost non-existent once again. I am sure the natural harmonic is reached at the mid 2000's and that is why it shook so badly there. Engine runs smooth as silk as we took it out of gear and ran up and down the RPM range and the thing was sweet. So what to do next? I have called a diver to get him to pull the prop and balance that but I am not sure since the Autostream is fairly new that that is the problem. Advice anyone???
 

Blitz

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Jul 10, 2007
709
Seidelmann 34 Atlantic Highlands, NJ
A diver is a good idea, as well as checking your shaft alignment.

Also, be sure that your transmission is shifting all the way in gear.

On app, so don't know your details (model or year of yanmar) but how old is the boat? Did this come on gradually or just all of a sudden. Was the boat ever chartered? The reason I ask is that if you have a trans like on my 1984 yanmar 3GM it might be that the cone is glazed. (Like brakes on a car that chatter) my solution was a rebuild with the shop removing the glazing solved the problem.

Good luck.
 
Oct 19, 2011
181
Hunter 42 Passage San Diego, CA
A diver is a good idea, as well as checking your shaft alignment.

Also, be sure that your transmission is shifting all the way in gear.

On app, so don't know your details (model or year of yanmar) but how old is the boat? Did this come on gradually or just all of a sudden. Was the boat ever chartered? The reason I ask is that if you have a trans like on my 1984 yanmar 3GM it might be that the cone is glazed. (Like brakes on a car that chatter) my solution was a rebuild with the shop removing the glazing solved the problem.

Good luck.
The boat is 1992 and the Yanmar is a 4JH2-TE. It was never chartered but the vibration has been there for a long time but just recently I was made aware of how bad it is at RPM's where we are trying to make headway in a "no wind" situation. The mechanic said he noted that there is a possibility of a worn drive plate and I am not sure what that is. He said it would not be an issue and to have it changed when I pulled her for bottom paint in a year or so. Sandy
 
Nov 6, 2006
10,093
Hunter 34 Mandeville Louisiana
Also check for a loose Cutless bearing and a bent shaft. Diver with a good straight edge can check for a bend..
 
Oct 19, 2011
181
Hunter 42 Passage San Diego, CA
Also check for a loose Cutless bearing and a bent shaft. Diver with a good straight edge can check for a bend..
I have a diver lined up to check the shaft but had not thought of the cutlass bearing. THANKS for that heads up! Sandy
 
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