Fuel Consumption vs. Cruising speed/rpm

luvinlife

My new to me boat is a  2006 270 FV with a Volvo 5.7 with 280 hp. With 3 male adults and half fuel on sea trial she was at 3700 rpms and about 25 mph. With just the admiral and me, we were planing at 3600 at similar speed. Top speed was 37.7 on the GPS. I have no idea on GPH but will get a better idea this summer. 

J3ff

here's the 383 chart.. 

randy56

Simple : I figure $100 to $150 for fuel per weekend.

Willhound

Handymans342 said:

Willhound, where in FL are you headed? Also remember that all those tax dollars goes to subsidies like your health system.

We have friends with property in Largo, the one near Clearwater, not Key Largo. Been going to the Clearwater Beach, St. Pete Beach area for over 25 years. Our favourite is Pass-A-Grille. As far as the gas tax, it's supposed to go towards better roads, but instead the government of the day sometimes decides to put it towards other things that better meet it's re-election goals. The alcohol and tobacco taxes are supposed to go towards health care, which makes sense, but same thing, also gets sidetracked sometimes. All that being said, yes, we are pretty lucky, basic health care is all covered so no complaints. It's not perfect, and I know a big debate in the US right now, but I have to say that overall, it's pretty good. Still pay extra for dental and physio, and most prescriptions, unless really low income, but the basics are covered. And depending on your thoughts on the subject, we can get medical cannabis....the debate is still out on that one....

Dream_Inn

randy56 said:

Simple : I figure $100 to $150 for fuel per weekend.

Well, I use that same number as well, but just for my hourly burn.

randy56

A ben franklin should take me 66 miles, @$3.00 per gal. figuring 2 mpg, if I run more or pull skier's it doubles. Figuring 200 mile range with 100 gal tank. 
Twins equal to double consumption, it's like having two boats. so are you at 1 mpg? with twins. 

Dream_Inn

randy56 said:

A ben franklin should take me 66 miles, @$3.00 per gal. figuring 2 mpg, if I run more or pull skier's it doubles. Figuring 200 mile range with 100 gal tank. 
Twins equal to double consumption, it's like having two boats. so are you at 1 mpg? with twins. 

If it were only that simple.  Weight, width, well, just pure size changes the numbers a bit.  On a really good day going with tide and wind, I may, just may, see 0.9 mpg.  But, typically it is 0.7 and sometimes 0.8 mpg.  Now, that is cruising about 31-33mph, which is moving pretty well for a boat that has a LOA over 42'.  I don't even look at my fuel burn at top speed, which is close to 45mph.

Willhound

So after 3 full seasons I'm reviving this thread to somewhat answer my own question.
I never could find a fuel graph for a 2000 Era FV270 with 5.7L EFI Gen+ but for the last 3 years I've tracked my fuel consumption and hours. My engine isn't VV compatible or I'd have it and I don't have a fuel flow meter. These numbers are an average of all hours run, so everything from idling at the dock to full burn. But most of the time I'm on plane at between 3400RPM/24mph and 3600RPM/27mph where the engine seems happiest and I can easily stay on plane with 2 to 3 adults, full fuel and water and gear. My "seat of the pants" makes me think that this is likely the sweet spot for max GPHvsMPH although I'd be happy to be proven wrong. I have been toying with the idea of running at another 200 RPM or so higher the next couple of tanks to see if it makes a difference better or worse.
My average over the 3 years has been 23.54 LPH or 6.22GPH. Wherever you see Gallons in the attached I've converted to USG, not Imperial. USD figures were converted using an average exchange rate over the last 3 years of $1.30CDN to $1USD. Average fuel cost per hour of $32.55 CDN or $24.54 USD. The first row entry is from the day we picked up the boat and filled it on the way to the lake. That fuel is not included in the averages.
I fill to full every fill up. For better or worse I don't believe in running around half empty and filling up around here is often a hassle so when I fill, I fill.
For all you numbers junkies out there like me.

Handymans342

7$ a gallon? Is that Canadian prices?

Willhound

Handymans342 said:

7$ a gallon? Is that Canadian prices?

Oops. Good catch @Handymans342. It was US gallons but I used the wrong exchange calculation in that column. Fixed now. The cost per hour in USD was correct though. New chart. Average of $3.84 US per gallon based on $1.35 per litre x 3.785 for USG x 0.75 for CDN to USD. There's some decimals not showing also.

Handymans342

Is your money that weak now? LOL

Willhound

Has been for 4 or 5 years. Last time we saw par was when oil was $150 a barrel and you guys were paying through the nose for it.

Black_Diamond

I run in the 30 gph at cruise. Twin 350 MAG MPI. 

Most boats run in the 1 mpg range. Saw a 40’ Formula on Mon with 4x 400R Mercs on the back. 72mph.  Can only imagine the gph at that speed!

Willhound

We have a lot of Formula and Fountain cigarette boats on our lake system. Even a big annual Poker Run. I call them 50 buck boats. As they go by I just keep repeating every second...50 bucks..50 bucks..50 bucks...

reneechris14

I have done the same thing I think I'm at about 10 gph over all will check when at the boat this weekend. Would love to know how many mile over all. You must have done alot more miles then me because Im at 4 boat unit also.

Ian

I recently posted some of my own data capture from VVM as well as a spreadsheet I used