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48' Viking w/ 860 MANS - low RPM

Discussion in 'Viking Yacht' started by duke84, Jul 23, 2016.

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  1. duke84, Jul 23, 2016
    #1
    duke84

    duke84 New Member

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    48 Viking with 860 mans only turning up to 2150 @ 29.5 kn. bottom is clean just has some shark skin on wheels. What could be the problem? Mechanics checked out the motors every thing was good.
  2. Capt J, Jul 23, 2016
    #2
    Capt J

    Capt J Senior Member

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    What do you mean by shark skin on the wheels? Any growth on the wheels can cut rpms pretty quickly. What year is the boat, how many hours, how much weight has been added?
  3. duke84, Jul 23, 2016
    #3
    duke84

    duke84 New Member

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    It's an 2004 . No tower,water maker or chipper. Has about 600 gallons of fuel in her. Shark skins I'm not sure what it is but when you rub the wheel it kind of feels like sand paper
  4. duke84, Jul 23, 2016
    #4
    duke84

    duke84 New Member

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    2000 hours
  5. Capt J, Jul 23, 2016
    #5
    Capt J

    Capt J Senior Member

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    Get the wheels as clean as you can with a diver. What you're describing on the wheels could contribute to a 50-100 rpm loss. It's not uncommon for a MAN boat with that age and hours to need the wheels cut a bit. I'd really check out the engines first, fuel pressure, boost pressure, etc. change all fuel filters, clean air filters...... how old are those?
  6. Capt Ralph, Jul 23, 2016
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    Is this a sudden loss of RPM in both engines?
    Clean bottom and fresh fuel filters are a must.
  7. duke84, Jul 23, 2016
    #7
    duke84

    duke84 New Member

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    I was on a sea trial. Not sure if sudden only ran the boat once. But yes both motors
  8. Capt Ralph, Jul 23, 2016
    #8
    Capt Ralph

    Capt Ralph Senior Member

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    So your shopping or selling?
  9. duke84, Jul 23, 2016
    #9
    duke84

    duke84 New Member

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    Shopping
  10. Capt Ralph, Jul 23, 2016
    #10
    Capt Ralph

    Capt Ralph Senior Member

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    So you don't know all the engine & ship history.

    Hopefully it's just a sudden case of dirty filters.
    There can be up to 4 (5) filters per engine.

    If this ship has been over-propped for a long time, you MAY be looking at engine issues in your future.
  11. duke84, Jul 23, 2016
    #11
    duke84

    duke84 New Member

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    It has the same wheels that it came with from the factory.
  12. Capt Ralph, Jul 23, 2016
    #12
    Capt Ralph

    Capt Ralph Senior Member

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    Same props, 2000 hours, 8 years, never in the shop, perfect blades now?

    I've never run aground either;:rolleyes:
  13. Capt Ralph, Jul 23, 2016
    #13
    Capt Ralph

    Capt Ralph Senior Member

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    It's would save some guessing if we knew ALL the fuel filters were services (with correct media) first.
    Inspecting the old filters could be helpful in understanding fuel quality.
  14. TMcG, Jul 23, 2016
    #14
    TMcG

    TMcG New Member

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    I agree, I have a 2003 version and she is very susceptible to dirty racors.
  15. Capt J, Jul 23, 2016
    #15
    Capt J

    Capt J Senior Member

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    Also the Man's like a lot of fuel flow. I ran a 1 year old 52' Cabo express with 1550hp MANs and same deal would only reach about 2175 rpms. The filters were all new, but racor 1000 valved to only 1 racor, when it was valved to both, it would make 2325 rpms.