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Thread: 54 motor yacht

  1. #21

    Re: 54 motor yacht

    Quote Originally Posted by Captain Ralph View Post
    It is nice for some folks to show them selves off well.
    For better or even to embarrass them self,, well.
    It is obvious that you have embarrassed your self with this comment.

    Yes, hull speed calculations are based on beam dimensions and further, where the widest part of the beam is is relation to the wet LOA or water line lenght.
    Every inch of beam makes a difference in hull drag.
    Every bit of hull drag makes a difference in propeller load, horsepower required to move the hull at a stated speed. and the amount of fuel required to produce required horsepower at the same stated speed.

    Every inch of wet surface matters including the density of the water against the surface. More drag at 4 feet vs at 1 foot for similar square inches.

    FI
    * themselves

    I don’t mind that you and Pascal have embarrassed yourselves. The idea that larger engines have no effect on fuel economy is absurd. Drop the same power in a 54MY and 53MY and fuel usage will be very close to the same at hull speed. That’s what we were talking about, wasn’t it?
    Randy Register - Kingston, TN
    www.yachtrelocation.com
    www.Safes4Guns.com
    aka Freebird aka Sparky1
    1965 41DC #93

  2. #22

    Re: 54 motor yacht

    Quote Originally Posted by Westfield 11 View Post
    Maybe that’s why hull speed calculations are never accurate when checked with accurate fuel flow meters? They are just a rough approximation due to factors like beam, draft and wetted surface area among others.
    Fuel flow meters calculate/confirm hull speed?

    Hull speed won’t be the most economical speed to run, it’s just the maximum speed you can run without requiring more power which relates to more fuel.

    Can we talk about rocket science now?
    Randy Register - Kingston, TN
    www.yachtrelocation.com
    www.Safes4Guns.com
    aka Freebird aka Sparky1
    1965 41DC #93

  3. #23

    Re: 54 motor yacht

    Bird, pay attention to your driving. You ARE driving, aren't you?

  4. #24

    Re: 54 motor yacht

    Quote Originally Posted by jim rosenthal View Post
    Bird, pay attention to your driving. You ARE driving, aren't you?
    Dave and Otto are driving at the moment.
    Randy Register - Kingston, TN
    www.yachtrelocation.com
    www.Safes4Guns.com
    aka Freebird aka Sparky1
    1965 41DC #93

  5. #25

    Re: 54 motor yacht

    The 60MY at hull speed of 10 knots with the same engines as the OP. Just imagine how much less fuel we would be burning if our beam were the same as his.
    Attached Images
    Randy Register - Kingston, TN
    www.yachtrelocation.com
    www.Safes4Guns.com
    aka Freebird aka Sparky1
    1965 41DC #93

  6. #26

    Re: 54 motor yacht

    Let me try this one last time.

    8V71 performance data
    http://powerforce.com/PDFs/2Cycle_En...DS_PF8V71T.pdf
    12v71

    http://www.powerforce.com/PDFs/2Cycl...S_PF12V71T.pdf

    Look at the bottom curve, the fuel per HP per hour... at the same RPM the 8v71 and 12v71 requires the same amount of fuel per horsepower. Ex 1300rpm both use 0.4 lbs an hour per BHP. Clearly engine size has no effect on fuel burn if producing the same horsepower.
    Pascal
    Miami, FL
    1970 53 MY #325 Cummins 6CTAs
    2014 26' gaff rigged sloop
    2007 Sandbarhopper 13
    12' Westphal Cat boat

  7. #27

    Re: 54 motor yacht

    Quote Originally Posted by Pascal View Post
    Let me try this one last time.

    8V71 performance data
    http://powerforce.com/PDFs/2Cycle_En...DS_PF8V71T.pdf
    12v71

    http://www.powerforce.com/PDFs/2Cycl...S_PF12V71T.pdf

    Look at the bottom curve, the fuel per HP per hour... at the same RPM the 8v71 and 12v71 requires the same amount of fuel per horsepower. Ex 1300rpm both use 0.4 lbs an hour per BHP. Clearly engine size has no effect on fuel burn if producing the same horsepower.
    Let ME try this again. OP is running 8V92 700HP engines. You said the engines were not the primary factor in a 54 vs 53 fuel consumption and said the extra beam was the culprit.

    Yes, if the 53 and 54 were equipped with the same power, the 53 would get better fuel economy, for all the reasons Captain Obvious pontificated. Even then, I’m guessing the difference between the two would be marginal. I’m sure I don’t have to remind you that Hatteras made the 1510’s because they were located inland. You can argue the point either way, but the 54 was a long awaited improvement over the classic, albeit dated 53.
    Randy Register - Kingston, TN
    www.yachtrelocation.com
    www.Safes4Guns.com
    aka Freebird aka Sparky1
    1965 41DC #93

  8. #28

    Re: 54 motor yacht

    Obviously more beam is an improvement... that s not the point. We re discussing why the wider beam boats burn more fuel at hull speed. You claimed it was due to the larger engines. The fuel burn curves posted above shows engine size is irrelevant as they burn the same fuel per hp. The difference comes from the wider beam
    Pascal
    Miami, FL
    1970 53 MY #325 Cummins 6CTAs
    2014 26' gaff rigged sloop
    2007 Sandbarhopper 13
    12' Westphal Cat boat

  9. #29

    Re: 54 motor yacht

    Post up some GPH numbers from DD on those 8V92’s vs the highest HP 8V71’s available in a 53, then we’ll see.
    Randy Register - Kingston, TN
    www.yachtrelocation.com
    www.Safes4Guns.com
    aka Freebird aka Sparky1
    1965 41DC #93

  10. #30

    Re: 54 motor yacht

    Quote Originally Posted by Freeebird View Post
    Post up some GPH numbers from DD on those 8V92’s vs the highest HP 8V71’s available in a 53, then we’ll see.
    http://www.powerforce.com/PDFs/2Cycl...DS_PF8V92T.pdf
    Pascal
    Miami, FL
    1970 53 MY #325 Cummins 6CTAs
    2014 26' gaff rigged sloop
    2007 Sandbarhopper 13
    12' Westphal Cat boat

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