fuel usage

[henryj2]

We have a 1978 Gulf Star 44' with twin original Perkins 254's with approx. 1,500 hours on each. With main and aux. fuel tank we can carry over 700 gals. of diesel fuel. We measure fuel usage by dip stick. On a return from Ensenada to San Diego at an average of about 9 knots it appears we used about 3 gallons per hour running both engines. Is this possible? When I tell people this they look at me like I'm nuts, which I may be but that is the reading I get and it's been about the same on other, shorter, voyages.

 

[Ski in NC]

At 9kts I think 3gph is low. Probably a bit more than that. I would guess 4ph. But Gulfstream are very slick hydrodynamic hulls, so maybe it is 3.

Also Perkins made a 6-354 and a 4-236, so probably not a 254.

 

[Nomad Willy]

If your boat takes 60hp to go 9 knots it's possible.
But more likely w a FD hull. HaHa maybe it is.
Like many you may be counting time running the clock and being at less that cruise throttle. The clock goes at one speed. Little periods of time spent stopping or slowing, warming up the engines ect ect will give you "wonderful" numbers. The time adds up more than most of us think.
Does your stern look more like a Bayliner trailerboat or a sailboat?

Ski didn't Perkins make a 154 or nearly so?

 

[Ski in NC]

Yep, they did make a 154. Maybe that is it.

 

[Nomad Willy]

Ski,
And if it was the same hull form (approx) as the Gulf Star 36 .....
Could easily do 1.5 gph oer engine. But more likely if he was say’in 8 knots.

 

[High Wire]

4 or 6 cyl?

 

[sunchaser]

Henry
Are your tanks cubes or conform to hull sides? If each inch of drawdown is a different volume, is your dipstick calibrated? Also 40 hours per year of use is interesting and less than 150 gallons per year on average.

Nice boat and great efficiency, my questions aside.

 

[henryj2]

Fuel usage

Thank you to those who replied.
The answers to the various questions posed are:
1. It is a 354 turbocharged. Would like to say it was a typo but more of a senior moment, I fear.
2. 6 cylinder.
3. Main tank conforms to hull shape. We also have an axillary tank under the aft deck that was originally (we believe) set up for water but was switched to fuel somewhere prior to our purchase.
4. Nomad Willy could also be correct, sloppy accounting for time under full power could account for part of what seems to me such stingy (although wonderful) fuel usage.
5. We have seen several Gulf Star sail boats with the exact, or nearly so, hull and have been told that was one of designers ideas, to make a hull that could serve either sail or power.

 

[tiltrider1]

44’ hulls don’t do 9 knots with out climbing the bow wave. I would believe those numbers at 8 knots but not at 9. I’m guessing there is some inaccuracies in the data. How did you measure fuel usage? How did you measure speed? How did you measure hours?

 

[henryj2]

Thanks for the comment:
Speed: garmin
Usage: as stated, dip stick
hours: clock
Could well have been 8 knots, note I said "approx. 9 knots" I agree could well have been only 8 or right at it on average. Bash from Ensenada to SD pretty rough and bouncy.

 

[tiltrider1]

Garmin sounds like GPS speed over ground. There are several things that could distort this number. Dip stick is not very accurate. Always Refilling the tanks to a fixed point tells exactly how much fuel was used. The clock doesn’t tell me much. I’m guessing you didn’t use the engine Hobbs meter. The clock on the wall is usually a guess as we rarely look at the clock when we start and stop the engines. It takes a bit of work, a lot of consistency And multiple attempts to zero in on a boats true fuel consumption.

 

[FF]

For boats used inland the usual hassle is many waterways are statute miles , not nautical miles.


5K = 6 Mph so its Ez to confuse 7+K as 9mph.