nautical miles per gallon, 28 te...

[tomcat rio]

...310 peninsular
...
i don't seem to see a heck of a big difference over the speed/rpm spectrum. (using a gps and a flowscan flow meter)
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i.e.,maybe 1.3nm/g to 1.63 nm/g
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i.e at 8 kts, i'm burning about 5-6 gph (1/33 nm/g)
at 20 kts/ 3400 rpm its burning 14-15 gph or so( 1.33 nmi/g)
best cruise is around 2800-2900, 15-16 kts, 9.5 - 10 gph (1.5-1.6 nmi/gal)
might be that the flow meter reads high at low flow. or maybe that's just the way things is.
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it does make me feel better if i think in statue miles per hour.
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pitch trim can vary speed up to about .7 kts
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not a big deal. i'm just a hopeless number cruncher.
i guess the rice burners do better, but i only spent $15k on the new peninsular this year. got about 85 hours on it... seems to be fine so far.

[DougSea]

Hey Tomcat,

When I first saw your 8 knot figures I thought "Holy Crap! Is he driving a cruise ship? 1/33 of a nautical mile per gallon?"

But no...I'm guessing we have a mis-placed "/"

I'll have to wait until next season when a flowscan and a clean bottom should be part of my boating experience to post some numbers. Got the call from the yard, she was hauled today...so sad.

[Mariner]

You are very lucky then. We have very large differences in economy based on speed.

At idle, we burn less than 1gph and go almost 4 knots. That's 4nm/gal. At max speed, we burn 24gph and go at best 17 knots (empty tanks). That's 0.7nm/gal.

[tomcat rio]

average fuel consumption (actual fuel purchased/ engine hour meter) is 6.87 gph.
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[tomcat rio]

...double checked total fuel consumption/ total hours..
burned 271 gallons in 85 hours. or just about 3.2 gph average.
that would seem to indicate that the flowscan meter is reading quite high.

[johnmurray]

The 3.2 gallons per hour average rate of fuel consumtion reported by tomcat rio roughly matches my experience. My boat is an Albin 30FC with the 315 Yanmar. In this part of the world we measure in litres and my experience over my first full season works out to slightly over a litre per mile per hour. At say, 12 miles per hour that is about 13 litres per hour or about 3.4 US gallons per hour. The engine efficiency in terms of fuel used per mile does not seem to change much regardless of speed.