yanmar fuel consumption/efficiency - 420 6CX(M)

[mlsoares]

I have been researching to determine gallons per hour at various speeds found nothing definitive

My engine is a 2001 Yanmar 420 6CX(M) -ETE

My guess is 7 gallons per hour @ 2100RPM

Boat is Albin 31 weight is 12,000 lbs

IS there data to determine?

Thanks

Michael

[Gmschuler]

I am in the process of going through the survey and is would like to know the proforormance specs. The engine is the 2002 Yanmar 420hp. I am very interested is what would be a normal cruising speed and fuel Gphat that speed?

[Chris & Dale]

June 1st, 2012 to today:
1. 160.1 hours using 585.33 gallons = 3.65 gph (wide range of conditions & speeds)
2. Worst gph avg. - 5.85 (Maiden voyage from Annapolis to Southport - hard driving, big currents)
3. Best gph avg. - 1.35 (3 days of King Mackerel fishing going hard to a spot and then at idle, dragging beefy bags)

Overall, I'm very pleased w/my fuel consumption, with a 13 year old Yanmar 300 with 1268 hours, and no engine or transmission problems.

[Gmschuler]

Thank you for the information. I never did find exactly what I was looking for in the way of real time fuel economy, but we did purchase the boat. At this point I do plan to put a FloScan on board. I am still looking at the two options for the Yanmar 6LY2-STE. I will be more than glad to post my results next year when see what It does under different conditions.

Fish on <*}}}}><
Greg

[Gmschuler]

This past winter I put on a FloScan unit. The installation was not too bad after I figured out where to mount the sensors. With diesel there are two sensors, feed and return. I mounted the gauge right nest to my other electronics. The unit works, however the calibration procedure is way more difficult than I expected. The instructions are not clear. There are two sets of DIP switches one for real time consumption and the other for the totalizer (total fuel used). To calibrate the real time use is recommends getting the information from the engine manufacturer as to how many gal per hour the engine should consume at idle. I called the local Yanmar rep and the bottom line is they had no clue. The instructions go onto say idle could be 1200, 1400 or 1800 no load RPM. Again it is hard to set the switches to a value that I don't know what it should be. My only thought is that I am missing a step.
As for the totalizer, the instructions say to run the boat for 20 to 30 hours, then fill it up and see if the meter reading is accurate, if not adjust the switches up or down on a percentage basis. Run the boat again for another 20 to 30 hours and check it against the actual fill up and make more adjustments. At this rate it could take a year to get it calibrated. I guess I thought the unit would just meter the actual usage and display the results, I just didn't see this calibration procedure coming. Eventually I will get the totalizer calibrated, still not sure about the real time usage.
In the mean time I found out that my tachometer was reading 100 RPM low at 1800. This Yanmar is rated at WOT fully loaded at 3300RPM. The best I could get on the tach was 3100 and with the tach not reading correctly it meant I was actually only getting 3000 or less rpm. That of course means the engine is being over loaded and the mechanic recommend rep itching the prop. We had a 24 X 22 non cupped 4 blade. The prop shop ran the numbers through their computer and came up with the optimum 24 X 20" NC 4 blade. So,I had it re-pitched. The results are exactly as you would expect. I now get WOT at 3300 and I lost 2 knots at the top end. Not to happy about that but it is what it is. The engine sounds much better throughout the entire throttle rang, the fuel economy did improve relatively speaking ( uses less fuel per hour, takes longer to get to the destination).
It looks like our normative cruising speed will be 12-13 knots at 2800 rpm at 10-11 GPH. At least that is what I think it will be.
We are heading out on a week long trip. I will have more data when I get back.