Fuel consumption calculation

[Sunpacceo]

I need some help determining how much fuel I am burning per hour. My understanding is that my B28 with its original 350' gassers burn rate is approx. 1.2 GPH but I was hoping to dial that it more accurately at all RPM's.

Is my option to install a Fuel Consumption Guage and if so, has anyone done this that could help suggest how?

Thanks gents

[Carl]

Yup, they are called flow meters. As to how they are connected you can look up "Flo-Scan".
They do not make them anymore as many motors now have that option built in, but the info is still online and you will find other manufactures.


In short-

You buy the kit for your motors, based on max fuel usage and whether the motor has a return line.

To install-
- a sensor is plumbed into each fuel line. ( 1 for each motor unless it has a return line then its 2 sensors per motor)

-sensor gets wired to the gauge which does the fancy calculations of what each motor is burning at that time and usually has a "Totalizer" that tabulates the combined consumption.



I think they are great...you can chart RPM, burn, speed and range. They are also great at telling you if a problem is creeping up...one motor burning more fuel. What I thought was real cool...say I'm doing 19knots, I can tweak the throttles a hair keep the 19knots, basically the same rpm but consumption drops a gallon or two. For me that's free money.

[Donmystic1]

If you have a modern Garmin gps they have an accessory that can be added as stated above to your fuel lines.
It reads out on your GPS.
Google Garmin for applications.
I use them and they work great
Don

[mike ohlstein]

My understanding is that my B28 with its original 350' gassers burn rate is approx. 1.2 GPH

Maybe at idle.... But you probably get about 1 MPG at cruise and .5 MPG at WOT (or less).

[Tommy]

What Mean Mike said...........the math was easy on my old 31 gasser: fuel burn was 25 gallons/hour at 25 miles/hour (with clean bottom and light load and calm water and a tail wind).

[Bruce]

A little secret..........

As a former floscan distributor and master installer the way I checked the basic accuracy of the fuel burned on the guage was have the customer top off their tanks.
Knowing the amount of fuel in gallons in the tank/tanks, I would have them run the boat keeping a log of basic idle, high speed and cruise speed times to get an across the board usage under many conditions including nm's run.

After using at least a third of a tank, refill to top off and get that number which would be the fuel burned. From there you can do a number of calculations.

Unless your doing a trip where 1/10th gallon accuracy is needed to make your destination without carrying portable fuel jugs, this gives a pretty good clue.

[Amberjack]

Sunpaccaeo-

If you have your mind set on flow gauges go for it and enjoy them but you don't have to have them to understand your fuel burn. I don't have a flow meter and removed my fuel tank gauge years ago (fuel tank fill gauges can be inaccurate with bad consequences) but still have a very good idea of my fuel burn.

I always fill to full at the fuel dock so I know fuel consumption between fills. The GPS trip meter gives the mileage (there is some technology on board) which provides the average per nautical mile, in my case a consistent 1.65 nm/gal. I also chart the speed vs rpm and have a good idea where the sweet spot is, a surprisingly wide band between about 2600 rpm and 3400 rpm.

It's a basic system but it works and it's foolproof. If I'm on a trip way up in BC away from the fuel docks I'll usually put a dipstick in the tank in the morning before extending further, mostly at my wife's insistence (she's smarter than me), but I've always been right on. Same thing at the fuel dock, I know within 5 gallons what the fill will be. It's old tech but it works for me.

[Tooeez]

I have the Floscan twinscan gauges on my 28 with 350 chevys. They are great--it's a shame they don't make them anymore, because they are great for fine tuning your speed to get the most efficiency--sometimes speeding up 100 or so rpm actually cuts the amount of fuel you are using! In any case, I have found using them that it does not matter what speed I run at (on plane) I get the same nmpg--just over 1 nautical mpg. So if I run at 16 knots I burn about 16 gallons an hour, at 19 knots 19 gph, at 22 knots 22 gph--I won't run the engines at cruise any faster than that. I have seen as good as 1.3 nmph with a light load and fair tide, and as little as .7 nmpg running into the tide with a dirty bottom. You can do a rough check by topping off the tank, keeping track of how many miles you run, and then topping off again. As long as you don't have a lot of idle or slow speed running to through off the calculation I think you will find that it comes out to just about 1 nmpg.

[Tony Meola]

http://www.cruzpro.com/fu60.html

Or you can install one of these which does what Bruce suggested but it does it for you. You just need a good fuel sender.

The Centroid works with the Cruz Pro sand eliminates a lot of the bouncing you get with a float sender.