Bene First 38 fuel consumption

[jgurley]

Just on the chance there's someone here that has a First 38 with the Perkins 4-108M and a Kiwi prop, what fuel consumption should I expect? I've googled things between 2.5 lph to double that.

I'm planning a long-ish trip and my local sailing grounds are a fast moving river so it's hard to take measurements.

Maybe someone can comment on how accurate the gauge is on the 125 liter original steel tank?

 

[Stu Jackson]

Measurements are easy to take because diesels run on hours per gallon (or gallons per hour), not miles per gallon. If you're bucking a headwind or currents, the engine doesn't know that at all (assuming reasonably normal cruising revs, i.e., not WOT for hours on end when you're pushing water against the hull with no increase in speed).

You can figure this out for yourself. Fill your tank, run an hour or two and refill. Should be a starting point. I keep careful track of my fuel fillups over time.

http://c34.org/bbs/index.php/topic,3841.0.html

If the bottom of your tank is narrower than the top, the fuel gauge will not be linear, since it's essentially a float device.

 

[jgurley]

I was hoping to avoid the analysis. I can't motor at cruising throttle very long without dealing with a drawbridge and the fuel dock is quite a ways from my dock, so neither input into the equation is very convenient. I'd guess I'd need more than a hour or two of test to make up for the fueling inaccuracy.

 

[Caboteur]

Fuel consumption

Hello JGURLEY,
Fuel consumption varies! There are many reasons for the variance; the two main ones will be RPM and load.
On a sailboat, load will vary with speed and wind and sea conditions. On my Beneteau 31 with a Yanmar 3YM20, it will vary from 1.0lph (liters per hour) at 2200RPM and windless flat water to 3.0lph at 3200RPM and wind and waves.
My former boat was a 38ft C&C with a Yanmar 3QM30 and would vary from 1.5lph to 3.5lph in similar conditions (the 3QM30 was a lower revving engine).
On a trip, I use 2.0lph as a yardstick for consumption (and carry a 20l fuel can): my 120l reservoir should give me 60 hours of fuel autonomy. Going south in the fall that is nearly 6 days... also time for taking on water and pumpout!
Your 125l tank should give you about 50 hours... also time for water, pumpout and some groceries!
Have a good trip
Pierre

 

[Philip_Oceanis 361]

In general when using "cruising rpm" (75-80% of max) an engine consumes 1lt/hr for every 10hp. I don't mean hp used but I am referring to the engine's horsepower. For instance a 10hp engine needs 1lt/hr, a 20hp engine 2lt/hr and so on. This is a very basic rule.

 

[sinbad51]

I have a Ben First 375 whiich is quite similar to your boat but i have a 3 cylinder Volvo.
I use about 3 LPH. I previously had a ben 430 with the newer 50 hP Perkins. it burned about 5 LPH and that was a heavier boat but newer design. My guess is 5 LPH would be pretty close