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  1. #1
    Petty Officer 2nd Class
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    Question How much Miles per Gallon should i get?

    How much miles per gallon should i get with my type boat ,mercruiser 5.7 5500 wot 15x17 prop, regal 233xl 60 gallon tank .what average miles should i be getting with a full tank of gas if my engine is properly tuned ?
    1992 regal ambassador 233xl Mercrusier 5.7 alpha 1 out drive.

  2. #2
    Lieutenant Commander
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    Default Re: How much Miles per Gallon should i get?

    Between 2 and 3 MPG unless you are at idle speed where you could get close to 5 MPG

  3. #3
    Commander 45Auto's Avatar
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    Default Re: How much Miles per Gallon should i get?

    Best you'll see is about 3.5 MPG at optimum cruise speed, which is probably right around 30 MPH on your boat. Averaged over a whole tank (no wake zones, above or below 30 MPH, etc) it will be between 2 and 3 MPG as Mischief says.
    Any opinions expressed above are worth exactly what you paid for them!

  4. #4
    Honorary Moderator Emeritus tashasdaddy's Avatar
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    Default Re: How much Miles per Gallon should i get?

    the reason being, is the motor is running a far more rpms, and an automobile engine, that has a transmisson, average auto engine runs in the neighborhood of 2,000-2,800 rpms.
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  5. #5
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    Default Re: How much Miles per Gallon should i get?

    Quote Originally Posted by tashasdaddy View Post
    the reason being, is the motor is running a far more rpms, and an automobile engine, that has a transmisson, average auto engine runs in the neighborhood of 2,000-2,800 rpms.
    Plus running a boat on a plane is like driving up an endless hill. Most of that fuel goes to making the wake.
    88 Larson Citation DC 175
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  6. #6
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    Default Re: How much Miles per Gallon should i get?

    I don't want to hijack anybody's post, but I think this is on the subject:

    TD,

    I remember you saying something in the past about improved gas mileage. something about cruising speed, increase throttle past where you want to be, then back the throttle off for better performance at that ideal speed...

    i could be way off with my explanation but i think i remember something about that.
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  7. #7
    Chief Petty Officer Woodnaut's Avatar
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    Default Re: How much Miles per Gallon should i get?

    In general, doesn't best fuel economy occur at a speed that is slightly above what is required to get up on a plane? (That is to say, a nice easy cruise at planing speeds is more economical than WOT.)

  8. #8
    Moderator QC's Avatar
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    Default Re: How much Miles per Gallon should i get?

    I think TD was referring to an Outboard rule of thumb. Almost all I/Os seem to have their nest fuel efficiency between 2500 and 3500 RPM. This has VERY LITTLE to do with engine RPM but more to do with hull efficiency. Most prop + gear ratio + horsepower combos just happen to fall into that RPM to achieve the approximately 30 MPH sweet spot that 45 Auto notes above . . .

    There is also no efficiency benefit to exceeding that speed and then slowing down . . . however . . . there is a benefit to slamming the throttle down to get up on plane . . . it happens faster that way

  9. #9
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    Default Re: How much Miles per Gallon should i get?

    Proper trimming is essential to obtain your best fuel rate. The less hull area that is in the water the less friction - better mpg or gpm. Don't confuse this with putting the bow up too high as it will defeat the whole purpose. As QC mentioned get her to planning speed as fast as practicable then throttle back to that sweet spot. A good fuel flow meter will help you a lot. Tabs are nice too!!
    Life may not be the party we hoped for, but while we are here we might as well dance

  10. #10
    Honorary Moderator Emeritus tashasdaddy's Avatar
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    Default Re: How much Miles per Gallon should i get?

    Fratalia17, to answer your question, it is for outboards, to run just under wot. you go to full throttle, then back off just a bit.
    i totally agree with QC and GC on the I/O.
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  11. #11
    Petty Officer 2nd Class
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    Default Re: How much Miles per Gallon should i get?

    Can this Boat take deep ocean also what is a good cruise speed going at a distance of 100 miles?
    1992 regal ambassador 233xl Mercrusier 5.7 alpha 1 out drive.

  12. #12
    Fleet Admiral Gary H NC's Avatar
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    Default Re: How much Miles per Gallon should i get?

    Quote Originally Posted by tigerhack View Post
    Can this Boat take deep ocean also what is a good cruise speed going at a distance of 100 miles?
    I think you would need a much bigger fuel tank to go 100 miles offshore.
    I would never do it in a 22-23 footer unless the weather was perfect,and i had a back up engine,plenty of fuel,EPIRB,Marine radio and all the other safety equiptment needed.

    I looked at some pics of that boat online,It looks pretty big for a 23...
    nice boat!


    1981 ChrisCraft 210 Scorpion K,175 Johnson SeaHorse

  13. #13
    Petty Officer 1st Class
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    Default Re: How much Miles per Gallon should i get?

    That boat is not ment for offshore use. Inshore/ Coastal use only.
    88 Larson Citation DC 175
    165HP 3.7L I4 (470) alpha 1

  14. #14
    Lieutenant Junior Grade marine4003's Avatar
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    Default Re: How much Miles per Gallon should i get?

    Quote Originally Posted by tigerhack View Post
    Can this Boat take deep ocean also what is a good cruise speed going at a distance of 100 miles?
    Why do i get the feeling that this is another one of those ...no matter how much we attempt to dissuade a fellow "boater" they do it anyway...i smell a statistic coming on..... sarcastic ? Yup,Reason = if your naive enough to ask weather or not to try 100 miles offshore in a small boat..then you don't belong on the ocean.
    Nec aspera terrent

  15. #15
    Admiral dingbat's Avatar
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    Default Re: How much Miles per Gallon should i get?

    Quote Originally Posted by tigerhack View Post
    Can this Boat take deep ocean also what is a good cruise speed going at a distance of 100 miles?

    Offshore the rule is 1/3 out, 1/3 back and 1/3 in reserve. With only a 60 gallon tank that limits you to using 20 gallons of fuel heading out.

    I regularly run 35-50 miles offshore to the fishing grounds, troll for 7-8 hours then head back to the dock. Most days I'll burn 60-65 gallons. Then there are the days that we have to slug our way out and back. On those days Iíll burn the contents of the main tank (92 gallons) and be well into the reserve (47 gallons) before we get back to the dock.

    As far as offshore is concerned, it 90% the captain and 10% the boat. Things can go from good to bad in a heart beat and its how the captain deals with the situation that vounts. Not how many motors you have or how big your boat is.

    If you donít have any offshore experience your best to use the buddy system with a couple of other boats. Buddying up is a good practice no matter what your skill level.
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