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Marlow 65' seatrial vibration

Discussion in 'Marlow Yacht' started by bayoubud, Mar 8, 2017.

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  1. Capt Ralph

    Capt Ralph Senior Member

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    To much unsupported shaft. (?)
  2. Cowger

    Cowger Member

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    Thanks for this feedback. As I'm trying to learn about this stuff... what's considered to be the proper amount of unsupported shaft? Is this something that could be corrected?
  3. Capt Ralph

    Capt Ralph Senior Member

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    I was just guessing but looking at those massive wheels and the skinny shafts brought this to mind.
    One bearing at the propeller and a floating hub in the engine room could lead to some shaft fling.

    I am not a heavy in this, just know enough to ask.

    Fixing it if I'm close?? Cutting off those ugly bilge keels and installing new struts and bearings correctly placed.

    This may be the reason so many of these boats are for sale.
  4. olderboater

    olderboater Senior Member

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    I'm sure there are ways to correct the problem up to and including rebuilding the hull, but as a practical matter I've never known a Marlow owner with these issues to resolve them. They either live with it or sell the boat.
  5. Cowger

    Cowger Member

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    Got it, thanks. I was thinking to have the shafts removed and shortened, but that was just an uninformed guess that is probably not possible.
  6. boatpoor

    boatpoor Member

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    Based on the photo, you don't have enough shaft to shorten.
  7. Cowger

    Cowger Member

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    Hmm, okay, I'm obviously confused. Too much unsupported shaft... does that mean "unsupported beyond the cutlass bearing" or "unsupported in those vertical fin things"???
  8. Capt J

    Capt J Senior Member

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    I think he means too much unsupported between the shaft log and the strut, which is encompased in those vertical fin things.
  9. Capt Ralph

    Capt Ralph Senior Member

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    Unsupported within those fin things.
    The shaft is not supported inside of those fin things until the cutlass just before the propeller.

    There is a science that spinning shafts cause drag. A whole stabilizer system has been designed on this Magnus Effect principal; spinning shafts or cylinders in the water.

    Some even go so far to seal the shaft way and fill with oil between the struts. Seems like a C F to me.

    I have yet to see any benefits but I am just a mild swamp tech. Others with higher pay scales think it needs to be covered so it is there.
    The additional thoughts to the bilge keel design; Those fin things; helps the directional water flow AND acts like additional keel surface area.
    IMHO;;; B S..
    More wetted surface drag and reducing natural clean water to the props.

    Again, I have to repeat; I am just a mild swamp tech.

    But if it looks like B S, acts like B S, Vibrates like (just) S, then it must be the reason that many very fine Marlow Yachts are for sale cheap, Law suits (buried issues) have been settled and your asking.
  10. Capt J

    Capt J Senior Member

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    Some Sportfish have shaft tubes. They found it adds about 1/2 a knot on a fast custom SF. But adds it's own issues as far as maintenance goes. So they stopped doing it.
  11. Capt Ralph

    Capt Ralph Senior Member

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    Quickly but well stated.
    SFs want every fraction of speed. Just like BuBa on the NASCAR track.
    But when it's not worth the expense (that's a lot), nothing beats swamp logic; KISS .
  12. Cowger

    Cowger Member

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    Ah, I see. Now your comments, and those of OB, make much more sense. If I am considering this boat (and I am), I will need to understand what maintenance is required on the shafts and associated bearings / hardware. Along with how she handles in rough seas, gets up on plane, vibrates, etc...
  13. Capt Ralph

    Capt Ralph Senior Member

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    Not to bash your thoughts and decision making. I do not want that to be the topic. From what we know, we pass on as warnings.
    We all could use some good and real feedback. Sadly, we get little.
    Could you reflect your purchase considerations? Did your trials prove no vibrations? Did your properly seasoned surveyor give you all thumbs up? Please fill us in us on your thoughts and experiences.
    Remember, we all can't push a Marlo, and are always learning. If you find a good ship, then fill us in. I'll be the first in line to help deliver her if you are all smiles.
    ,rc
  14. Capt Ralph

    Capt Ralph Senior Member

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    Again, I'm not a Marlo expert. I hope your surveyors are.
    On the maintenance issues, that is an additional venue I can not explain perfectly. Cutlass bearings and thrust / vibration assemblies have their own maintenance schedules that I can not recite. I do not expect it to exceed our usual thrust shaft routines we are accustomed to on non Marlow designs.
    However, our thrust shaft routines we are accustomed to do not cover the inhearant vibrations the Marlo Yachts seem to have on ;; some, lots, most models..

    Bottom line ;
    Survey very well. Sea trial hard.

    Yes, I know one family that luvs their Marlo. Only one.
    And I luv them also.
  15. Capt J

    Capt J Senior Member

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    If it were me, I wouldn't go any further than you already have. If you're insistent on moving forward, I would pay what I needed to pay to go on a seatrial at cruise speed in a sea, check what vibration there is, go in the engine room and look at the engines and shafts and see if they're smooth or jumping all over. Also a big issue with that boat is the height of the swim platform above the water. If you are at a dock or anchored and a 6" or larger wake heads towards the transom, it has nowhere to go, stuffs underneath the swim platform and the entire boat shudders and water shoots up straight in the air as high as the FB deck and gets the entire aft deck. I witnessed this at Charleston City marina when one was outside of me.
  16. Capt Ralph

    Capt Ralph Senior Member

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    Can you expand? No vents in the back porch??
    That is new to me. That does suck.
    Even my 42 year old (last month) Bert has wave vents in the back porch (platform).
  17. Capt J

    Capt J Senior Member

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    Look at post #86 on Page 5. No vents, the water rolls perfectly under the platform which is enclosed on the sides and has no vents and has nowhere to go and shudders the entire boat and it shoots up 10' high at the edge of the swim platform, sometimes rolls over the swim platform..........I've never seen anything like it. I could see the boat shuddering from across the dock on my boat.
  18. Capt Ralph

    Capt Ralph Senior Member

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    Yes, I notice the angled up area painted in red.
    Did not think about a vent then but now, must be one hell of a compressed sneeze from under that platform.
    F M
  19. Capt Ralph

    Capt Ralph Senior Member

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    Between the two of us, Maxwell House must keep going.
    I pour some hootch in my coffee this late.
    :oops::oops:
  20. Cowger

    Cowger Member

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    CaptJ, I do truly value your inputs and am trying to draw upon your experience. I'm trying to learn, so please forgive me as I continue to ask stupid questions.

    I agree that the view of the stern from this angle makes it look like wakes from behind hit two non-vented pockets:
    2.jpg

    But from this angle, the forward end of these pockets seem to be pretty gently angled downward -- would the wave energy not simply be pushed downward? I'm having trouble envisioning how it would be "sneezed" backwards or upward.
    6.jpg

    Please note that I'm only continuing to consider this boat as many have stated that each Marlow is different and needs to be evaluated on its individual merits and faults. I haven't been on her yet, but am scheduled to do so this Saturday.