Best possible gas mileage... ????

jjjtronics

jjjtronics

Junior Member
I have plans for a couple of long trips this summer, one of them over 100 miles away, I started asking myself what is my boat`s most fuel efficient speed, and I don`t have an answer. I guess the slowest planing speed will be the best, due to the least achievable drag from water/wind, but that is just a guess.
Has anybody ever figured this one out on a V20 ?
 
you can pick up a flowscan type meter from lowrance for about 125.00 and then with a gps you can do the math easily. my best guess would be about 2-3 mph at best
 
The most fuel efficient speed will not necessarily be the slowest planing speed.
One of those fuel flow meters and a GPS is about the only way to get it real close and not necessarily will the least fuel consumption be the most fuel efficient.
The top numbers is gallons of fuel used per hour, the left side numbers is the speed of the boat, all the other numbers in the chart are miles per gallon.
MPG-1.jpg


And I haven't taken the time to check all of this on my boat yet. So I have no idea what the best speed or rpm is to be the most efficient.
 
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Without a flow meter, the most economical RPM to run is normally around 3600-4000 if your propped to spin up to the high side on your WOT RPM's. A fuel flow meter is the best way to figure it out though. My boat gets about 2 NMPG from 3500-4300, the fuel consumption and speed both go up proportionaltly to each other. At 4300 the fuel burn begins to go up faster than the speed, and at 5400 they come back and almost match each other again. I can get right at 1.8-2 NMPG running flat out on mine, but it isn't very forgiving when you hit a wave at 50.
 
What kind of eng do you have ( I may have missed that?)
I have a 5.7 V/8 on my V 20 cuddy with a 4 barrell carb and I average 3.5+ mph at 3000rpm @ 30mph.

That equals out to a 60gal gas tank at 3.5miles per gal = 210 miles.
:beer:
 
3750-4100 RPM's will probably be your best. I am getting 3.5 mpg at that range of RPM's. Get a floscan and if you can afford it get one that automatically does the gph to mpg conversion (NMEA from GPS) so you can have instant readings. I just got the GFS10 from Garmin to integrate with my GPS440S and absolutely love it.

-Svence
 
csvencer said:
3750-4100 RPM's will probably be your best. I am getting 3.5 mpg at that range of RPM's. Get a floscan and if you can afford it get one that automatically does the gph to mpg conversion (NMEA from GPS) so you can have instant readings. I just got the GFS10 from Garmin to integrate with my GPS440S and absolutely love it.

-Svence
Click to expand...

same thing with the lowrance unit you get the ep10 fuel sender and the small guage then if you upgrade to a bigger gps unit it will work on that.
 
my cuddy had a 175 yamaha got 2 1/2 mpg at about 4500 rpm, 60 gal gas = 150 miles
Remeber the rule 1/3 to go 1/3 to come back and 1/3 for reserve and you will be fine.

If you go 100 miles will you have a gas statioin some were along the line??
 
Thanks ALL for the info.
I get around 2mpg on my 8 mile trip to Icaco Island, 4 miles @ 7knots going in ( upwind ), 22knots coming back ( downwind ).
I have an idea. I will pull a digital fish weighting scale I have somewhere, and do some calculations measuring the weight of the fuel used ( I`m using portable tanks ). That wil give me a fairly exact fuel usage using the weight of one gal of fuel/oil, and combine that to the average speed on that leg from the GPS. I will post the findings.

***I can guess that 2mpg is the rough magic number here.

THANKS FOR THE INFO AGAIN COMRADES.
 
YESSSSSS !!!
I want one of those !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
In my case it will pay for itself in fuel savings, but I need to come up with the "maryjanes"
( slang for $$$ ) in my area.
If I get to sell my Yami, I will be in the dealer next second.
 
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