fuel consumption

[Dave22q]

cruising at 5 kt 1800 RPM on Kubota 37 HP engine I burn about 2 g/hr. I'm curious how other do, especially those with heavy displacement hulls like my Morgan OI 33.

[racer1958]

2 liters an hour?
2 gallons an hour for a < 2 liter engine is a lot.

[wingssail]

Originally Posted by Dave22q

cruising at 5 kt 1800 RPM on Kubota 37 HP engine I burn about 2 g/hr. I'm curious how other do, especially those with heavy displacement hulls like my Morgan OI 33.

Sorry I cannot help you with the heavy displacement comparisons, my boat is 43' and weighs about 18000lbs.

However my 34 hp Yanmar at 1800rpm drives my boat at 5 knots and uses .49 gal per hour.

Another thought, you are driving that OI at over 75% of hull speed. For a hull shpae such as that you might be using a lot more power, however 2 gal/hr still seems very high

[StuM]

Originally Posted by Dave22q

cruising at 5 kt 1800 RPM on Kubota 37 HP engine I burn about 2 g/hr. I'm curious how other do, especially those with heavy displacement hulls like my Morgan OI 33.

That seems very high. A common rule of thumb is 1 gph for every 20HP generated.* You shouldn't be using anywhere near 40HP to push your boat at 5 kn.

* Imperial gallons!. Another one is 0.25 litre per hour per HP.
2 gal = 7.6 l (US gallons) or 9 l (real gallons )


Assuming you are talking about US gallons, that would still be 30HP.

[Sailmonkey]

We’ve got a 15000 boat with a similar hull shape. At 4ish knots were closer to .3gph.

You’ve got something wrong

[Uncle Bob]

32 ft heavy displacement hull, 50 hp Kubota, I achieve around 2.2 litres per hour at 2000 rpm.
I would suggest that you check your figures.

[pcmm]

Originally Posted by Dave22q

cruising at 5 kt 1800 RPM on Kubota 37 HP engine I burn about 2 g/hr. I'm curious how other do, especially those with heavy displacement hulls like my Morgan OI 33.

That seems high, how are you measuring? My 55hp (ish) Yanmar 4Jh2E on my Morgan OI 41 burns 1-1.3g/hr cruising at 6knts. I'm a bit heavier at between 25-27,000lbs displacement
]

[grantmc]

Heavy displacement 51 footer I'm currently sailing has a Ford Lehman 120hp and consumes 1.5 US gallon per hour at cruising speed.
My own 38 footer with a 72hp Mercedes uses 4 litres per hour.

[Nord Sal]

Westerbeke W52 @ 2100 rpm ~ 0.7 gph. 32' 13,000 lbs @ 6kts.