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Vibrations during sea trial

Discussion in 'Technical Discussion' started by Beauregard, Oct 13, 2014.

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  1. Beauregard

    Beauregard New Member

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    During a sea trial surveyor stated that he noticed vibration coming from the Starboard shaft above 2,600 RPM, none below that. He suspected a bend shaft or engine mis-alignment.

    A week later the vessel was hauled out and continued part 2 of the survey. This concluded that the shaft was not bent and the cut less was strong. My report states that the propellers need balancing. The owner said that he had a "mechanic look at the shaft and prop" and deemed it to be a loose zinc that slid down the shaft.

    I spoke with the surveyor on this and stated that the zinc would never create this vibration and is in fact the prop. I feel like I am getting jerked around.

    I figure I share this with you for thoughts......
  2. Capt Ralph

    Capt Ralph Senior Member

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    You or your surveyor observed this test with a dial indicator? At a few points on the shaft? Including the shaft end/tip?
    And somebody verified proper set of the prop on taper? While the dial indicator was in use, check prop tip position?
    But wait, there's more...
    Alignment could induce a D bent or whip that needs checking also.
    If it was out of the water and vibration comments were made, then this was the time to check these things and verify properly.

    Slipped zinc,,, may be,,, unlikely if it was a great vibration.
  3. Beauregard

    Beauregard New Member

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    rcrapps, not sure what the surveyor used in determining the shaft's condition. This is out of the report, "Both 1 1/2'' propeller shafts were tight to cutlass and turned true to axis. I noticed a significant amount of vibration. Since the cutlass bearing were tight, and the shafts were turning true (by eye), I believe that its a strong possibility that one or both propellers may need to be balanced".

    I doubt it was the zinc also..
  4. Old Phart

    Old Phart Senior Member

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    I dunno
    So, is this the only boat for sale?

    Next time, get a different surveyor.

    KeepOnTruckingT.jpg
  5. NYCAP123

    NYCAP123 Senior Member

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    " the shafts were turning true (by eye),"
    I think that answers rcrapps question.
    I'd like to have gotten more information. The zinc losening up sounds more like a result than a cause. I used to run a new Bertram with a vibration in the starboard side that we chased under warranty, but never cured.
  6. jhall767

    jhall767 Senior Member

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    You need to require them to cure the vibration prior to closing. Maybe it was the zinc. That's a nice theory but they need to demonstrate that it is cured on a sea trial. No different than an overheating engine.
  7. dsharp

    dsharp Senior Member

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    Do they have a spare set of props that they can put on? A bent prop will do more to cause vibration than alignment.
  8. Capt J

    Capt J Senior Member

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    The Vibration was probably caused by the stringers moving around and hull flexing at cruise causing the alignment to change......You know.....on those newer Bertrams and all......LOL
  9. Marmot

    Marmot Senior Member

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    You can waste a lot of time and money chasing phantoms and following advice from boat drivers. There are a number of possible sources that no one has mentioned such as exhaust resonance, an engine combustion issue, mounts, or some other mechanical source.

    The best way to resolve this is to hire a specialist firm to perform a vibration analysis to collect data that will provide information to help isolate the source, not just the symptom.
  10. NYCAP123

    NYCAP123 Senior Member

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    Although not something a buyer is likely to fork out for, this sounds like good advice for an owner. I'm familiar with firms that do this work on large structures, but wasn't aware of any that do it on boats. Sounds expensive. Any recommendations?
  11. olderboater

    olderboater Senior Member

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    Putting all this together it seems it had this problem during the sea trial, surveyor pointed it out, and he still bought the boat. Would seem now is the time to hire a professional to figure it out before it worsens and/or leads to more damage.
  12. NYCAP123

    NYCAP123 Senior Member

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    Don't think so. Sounds like they're still trying to sell it to him and are trying to excuse a problem the survey brought up. He needs to tell the seller that if it's an easy fix as they say, they should fix it and then they can talk. This could be nothing or it could be a BIG something.
  13. Old Phart

    Old Phart Senior Member

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    I dunno
    SeemsNormalToMe.jpg o_O

    Check posts for http://www.yachtforums.com/index.php?members/beauregard.43483/

    http://www.yachtforums.com/index.ph...tive-maintenance-new-owner.23731/#post-205545

    http://www.yachtforums.com/index.ph...tive-maintenance-new-owner.23731/#post-205550
  14. olderboater

    olderboater Senior Member

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    Not from another thread. "I Just bought a 1989 (37) Silverton with (2) 454 Crusader engines with only 450 hours total. This survey concluded as few "engine must do's" I need to complete in order to preserve continued service throughout the years, and Iam looking for your feedback." I thought as you at first until Old Phart asked "Does this boat also have a bad vibration
    and an obnoxious fume detector?" and he responded "Yes."
  15. NYCAP123

    NYCAP123 Senior Member

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    Sounds like someone needs to combine his threads.:rolleyes:
  16. Old Phart

    Old Phart Senior Member

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    I dunno
    Would help if a Senior Member were to read

    all of a new member's post

    in a Thread (Technical Discussion)

    before adamantly replying, in error. o_O


    You seem to be enjoying some fun learning the new YF website.

    Imagine how much fun someone who joined three (3) days ago

    must be having; trying to learn the rules and the new YF website.


    Would it prove end-of-life to you to simple post an Oops?
  17. NYCAP123

    NYCAP123 Senior Member

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    I re-read back to post #1 in the thread. Sorry I didn't research everything the OP has written on any YF thread. I didn't re-read your 1,284 posts before responding to you either. Sorry. There is life outside of YF to be taken care of. I'm sure the OP understands the advice. He's just in the owner's position rather than a potential buyer's. The recommendation remains the same.
  18. Old Phart

    Old Phart Senior Member

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    I dunno
    All 10 posts.
    Yes, that would be an exhausting task.
    Great advice (recommendation).
    You really believe the prior owner will fix anything, now?

    Here's something of help to you earlier, if you had taken the time to read post # 171 prior to asking the Admin (post 183).
  19. SFS

    SFS Senior Member

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    This gets very tiring.
  20. jhall767

    jhall767 Senior Member

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    x2

    We got it already.