Diesel Consumption per HP

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alec

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Does the team think that this rule of thumb is about right :-

0.055 Gals per hour per HP

I only have a 6 gallon tank and am aware that our Dutch neighbours are not too keen on us having spare cans of red diesel. I have not thought about this much in the past but feel I have to now.

I wrote this calculation some years ago but cannot remember where from.


Thanks in advance.
 
Sounds high to me.

My Bukh 20 consumes between 1. 5 and 2 litres/hour which equates to 0.075 and 0.1 litres/hour/hp.

Let you do the litres to gallons conversion, but its about a third of your figure

But thats a sailing boat chugging at 5 knots.

/forums/images/graemlins/frown.gif

MJ
 
[ QUOTE ]
my 28HP does 1.6litres/hour at 2000 revs (5 knots)

Can't make sense of your calculation - sure it wasn't litres not gallons?

[/ QUOTE ]


Works out about right I think for my boat.

Say Harwich to Ostend 75 miles.

9 hp engine, long keel, 3.5tons disp, 20' waterline.

I would have to run at not less than 80% to average 5 knots.

7.2hp x 0.055 galls x 15 hours = 5.94 galls

Sea state ?
 
Hopefully I can get this right but:

(cube the fraction of the rated power rpm) * (rated power/20) = number of gallons per hour.

Any errors are due to red wine which unfortunately can run an engine!
 
FWIW: I suspect the answer depends very much on how fast you run the engine; if you run it somewhat below full revs/full power then the difference in boat speed will be quite small but the engine will use a lot less fuel.
I seem to recall that fuel consumption for Yanmar 1GM (9 hp) is supposed to be slightly over 1 litre/hour at cruising (not max) revs; I get something like 0.5 litre/hour since I tend to run the engine at somewhat less than max revs, and much of the running time is low speed manoeuvres etc.
 
It's not the rated HP that counts, unless you're running flat out, it's the actual HP used.

Jissel has 28HP, which would mean around 1.5 gall/hr flat out, but when we crossed the channel last year, we used around 8 gals for the 12 hr trip, which suggests we were using about 13 HP. Doing 5kts or so, that sounds about right to me for a 24ft bilge keeler with a dirty bum.
 
The easy answer is to take road diesel its only red that will attract attention although of the 11 boats that went last week i dont recall anyone mentioning fuel being checked.

They did check passports and schenhgen form The police man actually filled out a new form for me as our next port was to be Holland or France and the download copy was pretty naff, VHF operators licence, boat registration.

As for fuel consumption 1.5ltrs per hr @ 2000 or 2.0ltrs per hr @ 2500

Thats for 37" footer 9 ton 39hp 3ym30 yanmar
 
Well quoting from the RNLI Handbook :- 'A diesel engine burns approximately one gallon per hour for every 20hp or one litre per hour for every 3.3lt/hr/kW'

I understand xgallons/litre per hour per xhp, but what does the last bit mean ? (one litre per hour for every 3.3ltr/hr/kW)

Mal
 
Just looked up the specific fuel consumption curves for the Yanmar GM series. Measured according to DIN6270B and expressed in grammes per KW or hp per hour.

Curves are almost identical for all sizes of engine and (using the KW figures) are at 320 at 1200rpm, lowest in the cruising range of 2400-3200 at about 280, rising to about 285 at maxiimum revs of 3400.

In other words, engine is at its most efficient at cruising revs and fuel consumption in relation to power rises slightly at higher revs.

As litre of diesel weighs approx 1kg. At 2800 revs a 1GM produces 5kw. at 280g per hour this gives an actual fuel consumption of about 1.4 litres an hour. At 2000 revs it would be just over 1 litre and at 3400 just over 1.7.

At cruising revs a 2GM would use about 3 litres an hour because it is producing twice the power and the specific consumption is the same.

I think my arithmetic is right! But happy to be corrected if I have missed something
 
Looks about right for an diesel engine running well up its rev range as it ought to be. You can get better fuel consumption by running diesels at low loads but it's bad for the engine to do it a lot.

I get 3 to 3.5 litres used an hour with a 27 hp diesel running mostly at 2800-3000 rpm (against a max of 3400 rpm). Probably therefore using 15-20 of the 27 hp - which comes out just below your figure
 
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