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Vibration issue

Discussion in 'Technical Discussion' started by Dan balmer, Jun 24, 2018.

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  1. Dan balmer, Jun 24, 2018
    #1
    Dan balmer

    Dan balmer Member

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    Hello everyone. I’m offshore the other day after 10hrs of slowgoing at night at 8 kts. And when going to cruise speed a vibration hum noise occurred that sounded like a dull roar that shivered thru the boat . I slowed down to idle ,and put each gear in reverse for a few seconds and the n went up to speed again and everything was fine . The survey had revealed that cutlass bearings on the 2 1/2 shafts were worn and were not tight anymore. I noticed that at least 3/16 to 1/4 “ gap when pressuring the shaft up against the bearing top. Anyone have any insights or experience with such things?
  2. Capt Ralph, Jun 24, 2018
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    How old are the bearings?
    How does the shaft contact area look?
  3. Dan balmer, Jun 25, 2018
    #3
    Dan balmer

    Dan balmer Member

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    Capt Ralph. Don’t know age of beatings but suspect there around 10 or more yrs. old. The rig runs incredibly smooth except for the one occasion previously mentioned. There is quite a bit of slop in them and seems to on the bottom if I’m remembering it right.
  4. Dan balmer, Jun 25, 2018
    #4
    Dan balmer

    Dan balmer Member

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    Well when I say on the bottom I’m actually meaning on the top or up and down
  5. Capt Ralph, Jun 25, 2018
    #5
    Capt Ralph

    Capt Ralph Senior Member

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    Around 10 years old, then they had a good life.
    Unless you picked up some trash or just came off a beach grounding, I don't thing going slow did anything.

    A better yard will have the correct tools to remove the bearing from the strut.
    Some boats may have another bearing in the shaft log.
    Depending on the design, the shaft may or may not have to be pulled.
    Inspect the shaft contact area well.

    Smile when you pull out the check book.
  6. Pascal, Jun 25, 2018
    #6
    Pascal

    Pascal Senior Member

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    Sounds to me like you picked up something on one of the wheels or shafts and it cleared itself when you reversed. No big deal. If the boat runs smoothly I wouldn't worry too much about the worn cutlass bearings but wouldn't wait too long to get them done either
  7. Capt J, Jun 25, 2018
    #7
    Capt J

    Capt J Senior Member

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    I think it's a carboned up turbo. I had this happen 10 years ago on a 12v71 TI after doing hull speed all night, made a very strange noise and vibration. After running at cruise for a little bit, it went away. I was on the Great Loop and left out of Fort Lauderdale I went into Brielle (ran at cruise for a few hours) to make it there. We immediately hauled the boat and the running gear was perfect. It subsequently happened again on the same trip.....but only after idling for a long time on the erie canal. It was the turbo on the port engine.
  8. Dan balmer, Jun 25, 2018
    #8
    Dan balmer

    Dan balmer Member

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    I think what happened is I picked up something and didn’t sling it due to slow going and when going up to higher rpm set off a rattle. Whatever was on there easily undid itself when easily reversed and neutraled which was a relief 100 miles offshore! No diving required.
  9. Dan balmer, Jun 25, 2018
    #9
    Dan balmer

    Dan balmer Member

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    Capt j. Thanks for that input on the turbo. If my running gear was perfect I would have to agree. But I know it is sloppy at the bearings so I’m suspecting that first. But who knows? Only time and money will tell. I’m hauling the rig next week for storage for my 6 month return to Connecticut Will change bearings when I return.