Best fuel economy

Discussion in 'Announcements & FAQs' started by Forever Mates, Aug 5, 2014.

  1. dpmulvey

    dpmulvey New Member

    Dec 19, 2007
    Homeport: Charles City, VA
    1999/2007 330 Sundancer Hardtop.
    6.2 Merc Horixons
    1.5:1 Velvet Drives

    How did you attach it to the hull bottom?
  2. aerobat77

    aerobat77 Member

    Aug 12, 2014
    2006 240 DA Sundancer
    5.0 MPI / Bravo III
    a typical planing hull with a gas engine will actually reach is best mpg at no wake speed nearly idle ;-)
  3. Creekwood

    Creekwood Well-Known Member GOLD Sponsor

    Apr 26, 2009
    Oakville and Georgian Bay, Ontario
    '97 330 Sundancer, Raymarine C80 suite with radar, Mercury 310 Hypalon w/8hp Yammie 2stk
    2X 454 carbs w/ vDrives
    I know that over 3500 the secondaries re full open, but on my 330, I think that about 3400 they are not fully open and the fuel burn is OK. That puts me right at 29-30 mph (25 knots) I have done reasonably long on plane cruises at that speed and I am quite sure that is the sweet spot. Now I have all chain rode (200ft) which puts a bit more weight up front and levels the boat nicely without much tab. Maybe that is my difference. In any event, I don't worry about fuel usage. Up here in Canada, our season is short. The more it burns, the more I am using it - and that's all good by me.
  4. aerobat77

    aerobat77 Member

    Aug 12, 2014
    2006 240 DA Sundancer
    5.0 MPI / Bravo III
    oh - you are right

    well, you are as a general thumb of rule spot on with your 3500 rpm,s . the exact value may vary a little dependant on the engine installed ( carb , efi , mpi ? ) , the driveratio , proppitch, hulldesign ( what is the minimum speed where the boat is fully on plane ? ) and more. but it starts to be hairsplitting.

    there are two sweet spots : 1) go slow at no wake speed 2) the lowest speed where the boat planes without being forced with full trim tabs etc to do so.

    keep away from transient speeds ( bow up, massive stern wakes) and from going WOT.

    best !
  5. Do Over

    Do Over Member

    Aug 9, 2014
    Lake of the Ozarks
    2002 340DA
    8.1 Horizons
    Missed this thread somehow.......good stuff......not for technical purposes but as a perfect example of how most forum threads on the ol worldwideweb go...generally speaking of course.

    Notice the copious use of .... to represent actually conversation.

    I'm gonna go look at fuel usage tables now :grin:

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