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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 ?
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.
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.
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.
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.
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.)
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
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!!
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.
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!
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.
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 I?ll 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 don?t 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.
