28TE fuel usage

[Dave39]

I bought this boat May of this year and usually cruise at 3200rpm. I have the Yanmar 315. On a 5 hour round trip to Block Island I used 58.8 gals for a gph of 11.4. The trip was with full tanks, mostly with the tide, and 2-3 footers.I recently spoke with an owner who had just come back from a long trip and said he ran "around" 3200 and used a little over 7gph. After reading a review of the 28 with actual burn rates, it appears I should be around 2800-2900 rather than 3200. I get over 22mph, but I'd sacrifice some speed for fuel savings. I'd be interested in your feedback for comparison purposes. Thanks.

[tomcat rio]

...so you can monitor real time fuel consumption and trim for best mpg.
once you have a baseline you can mess around with prop pitch diameter.
..
my new peninsular gives me about 15 kts at 2950 rpm at 10-11 gpm.
a gps helps to trim for best speed at a given rpm.
...
i'm not sure its possible to move a 9000 pound boat at 20 for much less than 12 gpm (real time consumption) .

[chiefrcd]

You're about right on where my burn rate is, I have a 99 6lp300 STE which is the same engine, rated a little different. At max cruise at 32/3300 rpms..which is about 21/22 mph...and I'm burning close to 11 gph...drop it just a bit with the rpms and you can drop the fuel burn considerably.

[JackK]

11 gph is a lot higher than my average. I don't have a floscan so I cannot give exact numbers. At 3200 rpm, I cruise between 17 and 18kn and fuel burn is around 7-8 gph.

My consumption will go up considerably if I run at 3500 rpm and 19-20 kn range. I tend not to because of this. A couple of knots isn't worth the extra fuel burn to me.

I keep logs for every trip and all fuel. I'm currently at 442 hrs and average under 6 gph overall.

Jack

[Denis]

Dave39, where are you located?

[digitrade]

I would suggest getting a fuel consumption chart which is on the literature for the 6LP engine. It gives maximum continuous fuel burn vs. engine rpm. My memory tells me at 3200 max continous fuel burn is about 9 gallons per hour.

3200 rpm the 11 plus gallons per hour is out of spec. The idea is that you can get more speed at a given rpm by overpropping but it causes overheating in the engine components and of couse extra strain and wear.

I installed my 3rd new 6LP engine in my 2000 model 28 recently. I normally am loaded very heavily so have less pitch and run at a slower speed than a light 28. But the max fuel consuption chart still holds.

I run at 3400 max cruise and never allow more than 10 gallons per hour. If seas are heavy with an extra heavy load I cut the throttle back to get back in the suggested performance curve.

At 3400 I only run at 15 to 16 knots and normally 9.5 gallons per hour.

I would suggest a flow meter for monitoring fuel consumption and also to tell if there is some problem that suddenly causes extra load on the engine which is otherwise perhaps not noticable.

[fairtide]

Digitrade writes that he has installed his third new Yanmar engine in his 28, so the one in operation is the fourth engine the boat has had. While his travels with the boat are greater than most of us will ever take, I was surprised to see that so many new engines were required since the boat was built in 2000. Questions for Digitrade:
About how many hours of use did you get from those engines and could the engines have been rebuilt rather than changed out?
Did you consider another manufacturer of engines or, as it seems, were you pleased with the service that you got from the Yanmars?

[chiefrcd]

Fairtide, I have not see him post in a long time, but somewhere on another post or another site he posted that he was getting in the 3000hour ish on these engines. I figured at that rate I'd either be in a nursing home or out of boating by the time I make 3000 hours. I'm averaging about 100 hours a year engine time.

[RicM]

Yeah, I seem to remember that he charters and runs huge hours/year. He wouldn't keep putting in Yanmars if he didn't like them.

[Maye Marie]

I have used the Yanmar fuel consumption graphs to determine fuel usage and so far they look to be fairly accurate. I used their flow numbers and my GPS and made up a performance chart for my self.

GPH Knot RPM
1.8 5.8 1200
1.9 6.8 1600
2.3 7.2 1800
2.8 7.9 2000
3.9 8.3 2200
4.5 9.9 2400
5.5 10.5 2600
6.5 12.0 2800
7.9 14.7 3000
9.0 16.7 3200
11.0 18.5 3400
13.3 20.0 3600
16.5 22.0 3800
18.0 24.5 3950

So far this year May Marie has ran for 245 hours. On vacation she logged over 400 nautical miles and we lived aboard her for a week and half.

[mhanna]

I was going to wait till I had a full year of data, but the conversation is open so....
Like Terry I have been tracking speed and fuel usage. The fuel usage from the below comes from the Yanmar specs, speed from GPS and this run was done @ 3/4 fuel, full water, 4 passengers, into a slight wind and lots of gear that built up over the year. Note the top end is ~20kts here. When the boat is lighter (1/2 fuel and me) it gets to 24kts at wot. So this is on the worst case end of the speed specs as far as I am concerned.
I plan on collecting many runs at various loads and will have more data for a better overall picture at the end of the year.
I tend to run about 3200rpm, except when I have nowhere to go and then run much less.

2001 28TE with 315 Yanmar





Matt

[Mariner]

Matt, that is GREAT info.

If you double those GPH numbers, you have a rough approximation of our fuel curve.

[Maye Marie]

Matt
The bigger question how did you get your graph and spread sheet in. I could not do get that dun.

[Mariner]

Terry,

The easiest way to post something like that in the forum is to take a "screen shot" while you have it up on your screen. If you press Alt+PrtScrn, it will capture the image of whatever window you have in the foreground and save it in the clipboard. Similarly, Ctrl+PrtScrn will capture the entire desktop. Then, you can open Microsoft Paint (or any image editing program) and hit Ctrl+V to paste it. From there you can edit and save it. Be sure to save it in .jpg format if you want to upload it here, or else it will take forever for anyone to download it.

[mhanna]

Mariner explained it right, its just a picture.

Matt