why is my 300 Sundancer going thru some much fuel?????

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by SeasTheDayAz, Jun 28, 2010.

  1. SeasTheDayAz

    SeasTheDayAz New Member

    1
    Jun 28, 2010
    arizona
    300 sundancer da 2005
    raymarine c seriers nav.
    twin 5.0 mercruiser w bravo III drives
    2005 300 Sundancer with twin 5.0's

    We are new at owning a searay and do not understand why the fuel consumption is big. We have several friends that own the same boat and some with bigger engines and do not go thru the fuel we do........and drive more then we do.
    We need some help and advise....
    What could be going on???????
     
  2. Voldad

    Voldad New Member

    104
    Mar 7, 2010
    Knoxville
    2005 280 Sundancer
    Twin 4.3 Alpha 1
    First you are burning a lot of fuel because it's a heavy boat with big engines. What are you calling burning too much fuel? Look at your smart craft gauges and see what the burn rate is. If you've compared those numbers with others - maybe something as simple as trim tabs are down, engine not trimmed right or you are just going too fast. I have an '05 280 Dancer with the twin 4.3's . . .and I'm surprised at my burn rate - 10GPH per engine at 3500RPM's. I usually cruise between 3200 and 3500 - just enough to keep it on plane.
     
  3. Dave S

    Dave S Well-Known Member TECHNICAL Contributor

    Oct 3, 2006
    Upstate South Carolina
    Boatless
    Boatless
    I agree with the comments above.

    Do you know what your burn rate is at any given speed (GPH)? What boat did you own before the 300DA? I know that moving from my 240SD to my 260DA more than doubled my fuel usage and at first it was a bit of a shocker.

    Dave
     
  4. phoenixhotrods

    phoenixhotrods New Member

    72
    Dec 6, 2010
    canada west coast
    1987 searay 270
    2 350, 260 alpha ones
    What do you guys burn trolling,6mph. GPH
     
  5. Presentation

    Presentation Well-Known Member TECHNICAL Contributor

    Oct 3, 2006
    Wisconsin - Winnebago Pool chain of lakes
    280 Sundancer, Westerbeke MPV generator
    twin 5.0's w/BIII drives
    We need some facts and figures to determine if you have an issue.

    We want to help you but with no data we can only offer guesses.

    Do you have a GPS with a trip odometer?

    Please fill, reset your trip odometer, keep GPS on at all times when you are using the boat, fill again and keep track of your miles traveled and fuel consumed.

    Do this a few times in a row then report back.
     
  6. Larry&Leisa

    Larry&Leisa Active Member

    Oct 26, 2006
    Keystone Lake Oklahoma
    1999 330EC
    454's
    You say friends with similar boats and engines are using much less. Are you sure no one is out joy riding in yours when you are away? ( yes it happens.. one of our own here on CSR had someone watching their patterns and figured out they only came down on weekends. The member thought someone was just stealing gas until a slip neighbor happened to see their boat going by in the middle of the week and asked them about it )

    Is their bottom growth? when was it last tuned up?
     
  7. skolbe

    skolbe Active Member

    Oct 3, 2006
    St. Louis, MO
    320 Sundancer, Mercury 310 Sport Inflatable Tohatsu 6HP
    350 Mag V-Drive - Kohler 5ecd
    I have a dock neighbor and friend that says he get great fuel mileage - but in reality they don't - A friend and old dock neighbor says he gets almost 3 miles to the gallon on a 330 Larson. Take what others say with a little skepticism.

    My dad has a 290 Amberjack with 5.0's and Bravo III's and while cruising he get's about 1.5 miles to the gallon. You should be in the same ballpark.
     
  8. Bridog

    Bridog Well-Known Member GOLD Sponsor

    Oct 4, 2006
    Gulf Shores AL / Brick NJ
    2016 19SPX OB
    Mercury 150 4S OB
    For reference....Same boat but with the 350's I average 1.2 MPG.
     
  9. C.W.

    C.W. New Member

    32
    Jul 28, 2010
    Kent Island
    310DA
    T5.0
    I've got the 310DA with twin 5.0 MPI/Bravo IIIs. Expect 1.2-1.5MPG (tailwind vs headwind).
    Some things that I've noticed that lower the MPGs:
    1. Growth on the bottom.
    2. Thermostat staying open (runs cooler, therefore richer)
    3. Using trim tabs while on plane (I'm still a newbie - it's all a learning experience)
    4. Props bent/gouged/wrong (not personally, but you never know when buying used)
     
  10. Dick Whetstone

    Dick Whetstone New Member

    116
    Jul 27, 2010
    South Carolina
    270 Sundancer
    7.4 MPI / Bravo 3
    My 2001 270DA (wide beam 270) with a single 7.4 and Bravo III running at 3500 RPM (30 MPH on the GPS) fully loaded with 100 gallons of fuel, 28 gallons of water, weekend provisions, and 4 passengers (approx 10000 lbs - my guess) consistantly gets 1.8 MPG on a 90 mile ICWW trip. With a larger (heavier) boat and twin 5.0's, you should expect considerably less MPG (IMO).
     
  11. J R Sparky

    J R Sparky New Member

    33
    Jan 2, 2010
    Central Florida
    300 Sundancer 2004, Garmin 4210 Plotter
    Magic Tilt w/ Electric/Hydraulic disc brakes,
    8.5 Zodiac w
    5.0s w/Bravo III Drives
    We'll be on the lake today and I'll make a chart at various RPMS, GPH and MPH. We just finished annual maintenance and bottom/outdrive painting. This will be a nice record for us in the future and give you a snapshot of the same boat/engine combo fuel consumption.
     
  12. J R Sparky

    J R Sparky New Member

    33
    Jan 2, 2010
    Central Florida
    300 Sundancer 2004, Garmin 4210 Plotter
    Magic Tilt w/ Electric/Hydraulic disc brakes,
    8.5 Zodiac w
    5.0s w/Bravo III Drives
    OKay, I have an Excel sheet but don't know how to post it. Can someone give me a hint??? :huh:
     
  13. J R Sparky

    J R Sparky New Member

    33
    Jan 2, 2010
    Central Florida
    300 Sundancer 2004, Garmin 4210 Plotter
    Magic Tilt w/ Electric/Hydraulic disc brakes,
    8.5 Zodiac w
    5.0s w/Bravo III Drives
    So far no one has offered a way to post an Excel spreadsheet, but the guys saying they acheive 1.8 MPG may be stretching things a tad bit. My best cruising efficency is
    app. 1.32 MPG. This is acheived with engine hours at 126 and 128 port and starboard and a relatively even load on the boat, and no wind. THe props have been polished and the bottom paint is new.
     
  14. C.W.

    C.W. New Member

    32
    Jul 28, 2010
    Kent Island
    310DA
    T5.0
    I don't know how to directly link the PDF, but if you search Google for:
    searay.com tst_9.pdf
    and look at the V-drive vs Stern Drive PDF, I think you will see that you're doing just fine MPG wise.
     
  15. swift1

    swift1 New Member

    33
    May 13, 2009
    Puget Sound
    290 Sundancer 1995
    Single 454 Merc/BravoIII
    Hey Sparky,
    Believe the 1.8 MPG figure; I get around 2 MPG lightly loaded in my 290- those of us with single engine and B3 do burn much less than you with (any) twins.
     

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