Fuel consumption on 40' Hunter

Don S/V ILLusion · Apr 19, 2010

Figure 1 gal/hr at a reasonable cruising RPM, slightly more if below 2000 RPM. You can find burn rates vs. RPM at the Yanmarhelp.com site.

Vinny · Apr 19, 2010

Doug,

The burn rate for a 4JHE in a Hunter 40 Legend at 2,700 - 2,800 rpm (which is the correct rpm for this engine) will be about 1 gal per hour. So 6.5 knots average is 7.5 MPH so 700 miles will take the better part of 100 gals of fuel and five days. Unless you can sail most of it or a lot of it depends on the route you will be taking.

Where is the trip to and from? Open ocean? My Hunter 40 came from Ft. Pierce FL to Beaufort NC on the 38 gals in the tank and six 5-gal Gerry cans on deck. Open ocean direct 3.5 days

Just as important as to how much fuel you have is does it have a Racor between the main tank and the engine and do you have a good supply of filters for the Racor and the filter that is on the engine? At least 5 of each. If you are in open ocean the stuff on the bottom and sides of the tank is going to be jarred loose and it will clog the filters.

Capt. Ron you want to chime in here?

captron · Apr 19, 2010

I agree w/ Capt. Vinny, you don't state where this 700 mile trip takes place from where to where?? meaning are you offshore, ICW, a combination of both?? an example of the variables you might encounter offshore trip south to north you could take advantage of the gulf stream and pick up 2/3 knot boost., going the opposite way prevaling winds are starting to switch out out of the SE or SW could be on you nose?? ICW you have tidal currents that will affect you and knock your speed up or down depending on how you catch the current. and as Vinny said take plenty of extra fuel filters for the primary as well as the engine filter. aand if you don't have a Racor primary filter on the boat I would sure put one on before I made the trip. On my delivery from Ft. Lauderdale to (planned New Bern, NC) 2nd day out about 60 miles off the coast of SC an un-forecasted Northeaster blew up (25 to 30 knot's and 12'+ seas for 16 hours) end result was running out of fuel 120 miles offshore of Wrightsville Beach NC (40 gal tank plus 4/ 5gal gerry jugs) and had to get towed in to Wrightsville Beach, NC no problem there, but it added an extra day to our trip as we continued the balance of the trip motoring up the ICW, and trust me it's no fun changing fuel filters in 12'+ seas.
The point being, just be prepared for the worst case scenario, because "if it's going to happen, its going to happen out there!"

Capt. Ron.;

Benny · Apr 19, 2010

About 1 gallon an hour, it is the approximate burn rate for the engine. The boat, wind strength and direction and currents will just determine the speed and range you will have with that burn rate under power.

Benny · Apr 19, 2010

When calculating range it is best done on the water, on course accordying to to the prevalent conditions. A 15% of the fuel in the tank should be considered as a reserve and not used as part of the calculations. Not all the fuel in the tank is usable as a couple of gallons are usually required to prevent the fuel pickup from sucking air. If you are doing a coastal trip you can plan for refueling points but if it is an offshore passage you will need need to carry all the fuel you can and then have a conservation plan.

Graysailor · Apr 21, 2010

I always assume 1 gallon per hour. However, on my trip from San Francisco to La Paz, MX. I was closer to .75 gallons per hour. This was on a '08 Hunter41, 54HP Yanmar. Virtually all downwind and about 22-2400rpm. I was very easy on the engine.

Vinny · Apr 22, 2010

Graysailor said:
Virtually all downwind and about 22-2400rpm. I was very easy on the engine.

Not easy at all. The time on the engine is the time and if at that rpm you did not maintain the internal parts to the proper temp then you were harder than if you would have run at 80% of full throttle. Just a fact.

Fred7825 · Apr 26, 2010

Whoa. Lets see, the guy drives from SF to Mexico @ 2200-2400 rpm and he doesn't get the engine up to "temp"? I don't think so. What fact are you refering to?

waternwaves · Apr 27, 2010

First question........4JHE right? on an 85, not 4JH3. I am asking because the older non turbo engine was just a regular 4JHE

well, my 1985 H40 with that 4JHE (40hp continuous/44 hp 1hr) engine burns about a gallon an hour at cruise.

but my Yanmar Service Manual, Chapter 1, page 1-6, Fig. 4-1 shows 75% cruise at about (30 HP) 3200 rpm. max at 3500 rpm. engine power available. So it looks like the power band 75-80 % cruise is closer to 2800-3000

The 2800 rpm as suggested above is only about 50% prop power and I have not found anywhere in the engine manual where that 50% is the suggested operating range. There just isn;t much load on the engine from most props at 2600

below is a copy of the engine/fuel curves my understanding based on owning a is the max prop has similar prop curve, but the slope of the curve is steeper at the high end (the MAX prop is really a good meaty prop with big bite at the high end). so even though you are showing 2600-2800 rpm with a regular prop you are only going to be getting out about 18 to 20 hp at that rpm, and figure about 15 to 20% more power so maybe 22-24 hp out of a max prop at that lower engine speed. For a standard clean prop from hunter, 75% load doesnt happen till about 3000-3200 rpm depending on how much fouling is on the prop.

Graysailor · Apr 30, 2010

???

Fred7825 said:
Whoa. Lets see, the guy drives from SF to Mexico @ 2200-2400 rpm and he doesn't get the engine up to "temp"? I don't think so. What fact are you refering to?

What is your question? I was running at 75% on the low side and 80% on the high side. Operating temp was fine. Don't have a clue what your referring too.

Graysailor · Apr 30, 2010

I was

Vinny said:
Not easy at all. The time on the engine is the time and if at that rpm you did not maintain the internal parts to the proper temp then you were harder than if you would have run at 80% of full throttle. Just a fact.

Ran at 75% on the low side and 80% on the high side. Engine temp was just fine. Not sure what you are referring too.

Vinny · May 2, 2010

Graysailor said:
Ran at 75% on the low side and 80% on the high side. Engine temp was just fine. Not sure what you are referring too.

Gents,

This has been beat to death on Diesel Form may times. The answers are always the same and they come from some pretty knowledgeable folks. Run a diesel engine at 80% of the max rpm to obtain the correct internal engine temps. Internal does not mean what your gauge is reading, your gauge (of which a stock 40 Legend does not have) is reading the fresh water or raw water temp. Internal is inside the cylinder and the cylinder head. Which we have no way to read. The real temp we should be concerned with is exhaust gas, according to the folks that know but that is a whole other subject.

So run it at 2,000 or 3,400 or what ever floats your boat. I'm just stating the facts as they are for any diesel engine. 80% of max rpm for a 4JHE is 2,800 and at that rpm it will burn somewhere around 1 US Gal an hour depending on how clean the prop and bottom is.