Fuel consumption question

[tireman]

Just bought a new Jeanneau 42DS with a 54 hp yanmar. I'm trying to get an idea of fuel rate consumption at different power settings so I can guage my range for trip to home port (plan to motor quite a bit as time is a problem). Boat holds 63 U.S. gallons. I've tried yanmar website and I've been through the Yanmar engine manual but no clues as to what I can expect. Can anybody point me to a source for this information or give me even an estimate of this engines range.

[kd3pc]

I have an older hunter similar in size to your J, with the Yanmar 4JH2 57-65hp depending on who you like.

I use a gallon an hour for budgeting fuel, actual use is closer to .6 gal per hour as I use 2200-2400 rpm for most motoring, as you near top rpm, 3000 in my case...it approaches the 1 gal per hour.

Enjoy your new boat, they are excellent, I had an '84 jeanneau and loved her most of any boat since.

[tireman]

Thats the first time I've ever posted to a forum and within 5 minutes I get a good answer. Thanks

[Minnewaska]

I find the last knot of boat speed will increase fuel burn by 25%-50%. Said differently, you can substantially extend range by pulling back a little on the throttle. To get these precise burn rates, I suggest a real life test. Fill the tanks and go cruising at a standard power setting. Top them off and do the math.

To be accurate, this takes many hours of cruising. Not sure how far your delivery will be, but it could be done on an early leg or two that are well within safe estimates.

[sck5]

it also depends a lot on sea state. and if you can get any help at all from your sails it will make a big difference. Keep the main up if you can.

[rbarkas]

We've put 250 hours on a 42I performance model with the same engine as your 42DS since October. Our overall consumption has been 0.82 gallons per hour.

We run our engine (after the breakin period) mostly at 2000 RPM and get about 7 knots from the boat. I can run it at 2400 and get between 8 and 8.3 knots depending on Sea State. The fuel consumption really goes up and the fuel cost to get more than 7 knots is pretty steep. Not only that but engine noise and vibration go up over 2000 rpm too.

Your speeds may vary due to the prop on your boat - we have a MaxProp classic 3 blade on ours.

We've motored far more than we wanted to in the first 6 months we've had the boat as we've done quite a bit of coastal cruising (circumnavigating Tasmania) where for some reason the weather gods haven't smiled on us (either 30 knots right on the nose or 4 knots up the stern).

I was pleasantly surprised at the low fuel consumption. Yanmars fuel graph indicated that we should expect to use quite a bit more fuel than this.

The engine has been 100% reliable, with low noise and vibration. The engine compartment exhaust blower is sometimes the most objectionable noise on our boat.

I agree with what Minnewaska said - gather your own data and understand that the fuel consumption / speed curve gets pretty steep toward the top end.

[dhays]

I have a Catalina 400 with a Yanmar 4JH4E engine which supposedly produced a max 54hp at 3000 rpm. Actual fuel consumption will depend on hull, transmission, prop, auxiliary equipment, wind, and sea state.

I've not used mine enough yet to get a good feel for fuel consumption. However, Catalina lists fuel consumption to be 1.25 gph at 2800 rpm. Looking at the fuel consumption graph from Yanmar, it appears that fuel consumption at cruising rpms of 2400 to 2500 would be closer to about .8 gph.

As always, YMMV.

Dave

[tireman]

Where's this fuel graph you're all talking about? That's what I've been looking for. Not on website and can't find it in Yanmar engine manual that came with boat.

[CaptainForce]

I have 5,175hrs on my Yanmar 4JH3E and I typically push my 26,000lb Morgan at 6.5kts running at 2500rpm with a 3-blade 18x13 prop at .9gph.

[rbarkas]

Here you go - found near the bottom of the brochure that the URL takes you to.



YANMAR Diesel Power - JH3/JH4 Series Marine Engine