Fuel Consumtion

[Triton]

I just worked out our fuel consumption over the last 1000 engine hours and it comes to 1.25 litres per hour.

The engine is in good condition (Nanni Diesel 4.195), 3000 hours on the clock and runs clean.

 

Is 1.25 litres per hour good, bad or average for the above engine in a 60 foot boat??? The engine is used for propulsion only as we run a generator for battery charging etc. when moored up for a few days. We are CCers.

[wrigglefingers]

I just worked out our fuel consumption over the last 1000 engine hours and it comes to 1.25 litres per hour.

The engine is in good condition (Nanni Diesel 4.195), 3000 hours on the clock and runs clean.

 

Is 1.25 litres per hour good, bad or average for the above engine in a 60 foot boat??? The engine is used for propulsion only as we run a generator for battery charging etc. when moored up for a few days. We are CCers.

 

Seems about right to me. The Beta 43 (3000 hours too) in Surprise consumes just a fraction over a litre of diesel an hour at tickover (950rpm) and around 1.25lts when pushed harder (1200rpm). I think that my Beta is fairly economical compared to the old SR2 I had which ran filthy and ate the stuff. Mind you the diesel consumption was nothing to the amount of oil she digested.

[Triton]

Seems about right to me. The Beta 43 (3000 hours too) in Surprise consumes just a fraction over a litre of diesel an hour at tickover (950rpm) and around 1.25lts when pushed harder (1200rpm). I think that my Beta is fairly economical compared to the old SR2 I had which ran filthy and ate the stuff. Mind you the diesel consumption was nothing to the amount of oil she digested.

Thanks, I had the impression from other posts that the average usage seemed to be around 1 litre per hour so thought my 1.25 was maybe on the high side.

[alan_fincher]

Thanks, I had the impression from other posts that the average usage seemed to be around 1 litre per hour so thought my 1.25 was maybe on the high side.

I'd say it's pretty good for a boat of that size.

 

We get more like 1.3 to 1.4 in a 50 foot, but that is with an elderly BMC of unknown history, and probably not the most fuel efficient engine around.

 

I'm doubtful of claims of no more than 1 litre per hour in big boats, personally.

[Keeping Up]

I'd say that's fairly typical. We use about 1.5 litres per hour on our 67-foot boat when we're dawdling around. When we're moving more rapidly we use 2 litres per hour, and on big rivers we have sometimes managed to use 3 litres per hour.

[Athy]

Does nobody express fuel consumption in miles per gallon? I kept records of our last boat's fuel use (40-footer with Rigas engine) and we averaged about 7 miles per gallon - though of course this figure would include the times when we ran the engine to charge the batteries.

[Keeping Up]

Well I know that I consistently average between 2.1 mph and 2.3 mph, year after year (that's over 20 years at roughly 1000 miles per year). So if my calculations are correct my 1.5 litres per hour works out at 6 or 7 mpg too.

[dor]

Travelling (as opposed to battery charging) I get about 1.3 - 1.4 litres per hour on a 57ft boat with a 42HP Vetus.

[John Orentas]

They used to say that a good Lister SR2 would use a gallon every three hours, given that you would expect a more modern engine to be more efficient I would say that was about right.. From my own experience my 2.1 litre engine would generally produce similar figures but when the power was turned up on a river the consumption would go through the roof..

 

It is all as you might expect really, and diesels are good at this, you pay for the amount of power you produce, almost regardless of engine type.

 

Off topic. A friend of mine had a Ford Granada which was fitted with one of those, fashionable at the time displays which would tell you anything including a real time fuel consumption indicator, once on a slight gradient on the motorway he looked up at his toy, it was showing 6mpg.. He slowed down!

Edited October 21, 2008 by John Orentas

[chris w]

I drove around recently with the fuel consumption computer display showing on my car and it certainly does make one more parsimonious with fuel. I found that on a 50 mile motorway journey (with the cruise control set at high 70's) and a few miles of town work at either end, I managed to get an overall consumption of 30.4mpg.

 

Doesn't sound that spectacular until I tell you this is a 4.2 litre, V8, twin-supercharged engine of 420HP. The fuel consumption gauge certainly eases some of the lead out of one's shoe!! Hence Lead-Free fuel I guess...

 

Chris

[carlt]

I drove around recently with the fuel consumption computer display showing on my car and it certainly does make one more parsimonious with fuel. I found that on a 50 mile motorway journey (with the cruise control set at high 70's) and a few miles of town work at either end, I managed to get an overall consumption of 30.4mpg.

 

Doesn't sound that spectacular until I tell you this is a 4.2 litre, V8, twin-supercharged engine of 420HP. The fuel consumption gauge certainly eases some of the lead out of one's shoe!! Hence Lead-Free fuel I guess...

 

Chris

you just had to tell us, didn't you

[chris w]

you just had to tell us, didn't you

If you're that green with envy Carl, you always have the option to block my posts........ it's YOUR choice. I just know you're a balanced sort of guy - ie: a chip on both shoulders

 

Chris

[carlt]

If you're that green with envy Carl, you always have the option to block my posts........ it's YOUR choice. I just know you're a balanced sort of guy - ie: a chip on both shoulders

 

Chris

On the contrary, Chris. I am perfectly happy with my vehicles and am entertained by your insecurities, so I won't be blocking your posts.

 

You are mistaking envy for pity.

[chris w]

You are mistaking envy for pity.

 

I don't think so.................................

[carlt]

I don't think so.................................

I know you don't. That just makes it all the more pitiful.

[Triton]

Thanks to all for the responses, I am feeling much happier now about my fuel consumption.

[Proper Job]

I've just checked my consumption. I filled her up and have kept a good record of running hours and then just fill up again (thought I'de do it before 31st ).

 

I've averaged just under 4 hours to the gallon with a 4.2 litre, 3 cylinder. That'll do me.

[Tony Brooks]

They used to say that a good Lister SR2 would use a gallon every three hours, given that you would expect a more modern engine to be more efficient I would say that was about right.. From my own experience my 2.1 litre engine would generally produce similar figures but when the power was turned up on a river the consumption would go through the roof..

 

It is all as you might expect really, and diesels are good at this, you pay for the amount of power you produce, almost regardless of engine type.

 

snip

 

 

As an aside to this. Diesels with glowplugs force their air through a small hole in the cylinder head on each compression stroke. The majority without glowplugs do not.

 

The faster you run a glow plug diesel the more energy/force it requires to get the air through that small hole in the time available so a fair bit of energy is used just doing that. This means that at canal speeds both types of diesel return similar consumptions but as you start to push the speed up the glowplug diesels consume rather more diesel for the same speed & load.

 

I knew a taxi driver who took his family on holiday in the diesel taxi and came back moaning that he only got 30mpg instead of the 45 he was used to. It was just the small hole and loads of motorways (oh and a heavy right foot!).

 

This is why I have a non-glowplug engine and am happy to put up with a bit of low speed exhaust smoke - but thats another story.

[n.b.Goldie]

As an aside to this. Diesels with glowplugs force their air through a small hole in the cylinder head on each compression stroke. The majority without glowplugs do not.

 

The faster you run a glow plug diesel the more energy/force it requires to get the air through that small hole in the time available so a fair bit of energy is used just doing that. This means that at canal speeds both types of diesel return similar consumptions but as you start to push the speed up the glowplug diesels consume rather more diesel for the same speed & load.

 

I knew a taxi driver who took his family on holiday in the diesel taxi and came back moaning that he only got 30mpg instead of the 45 he was used to. It was just the small hole and loads of motorways (oh and a heavy right foot!).

 

This is why I have a non-glowplug engine and am happy to put up with a bit of low speed exhaust smoke - but thats another story.

I am not sure i have understood the difference between glowplug and non-glowplug diesels. I thought the glowplugs were just for starting. Are you saying that they are used whilst the engine is running? I apologise if i have mis-understood you.

[Tiny]

I must admit to never thinking in terms of MPG for the boat engine. In terms of litres we seem to do around a litre an hour on average - which seems OK. But translate this into MPG - given we average a tad over 2.5 mph and you end up with about 12MPG.

 

This makes the engine sound massive - like one of those huge US gas guzzlers instead of an engine smaller than the one in our small car (which does 40+MPG). And, in fact used by the boat that gallon is a whole days average fuel consumption which moves a 52 foot boat and charges batteries, heats the water etc. as well.

[Tony Brooks]

I am not sure i have understood the difference between glowplug and non-glowplug diesels. I thought the glowplugs were just for starting. Are you saying that they are used whilst the engine is running? I apologise if i have mis-understood you.

 

 

The indirect injection engines start combustion in a little spherical chamber in the cylinder head (about prune sized) joined to the cylinder bay a small hole. This gives very high air flows around the chamber which helps to give clean combustion at low speed. Unfortunately the larger surface areas involved tend to rob heat from compression making these engines harder to cold start than the other sort - hence the need of many of such engines to use glowplugs for easy starting. In our branch of the marine trade they are usually turned off as soon as the engine starts.

 

Non-glowplug engines do all the combustion in the main cylinder which causes low air flows at low speeds and thus a tendency to smoke a bit on idle.

 

I used the terms glow plug and non-glowplug to save possibly confusing people with direct and indirect injection engines.

 

Modern cars do use glowplugs in direct injection engines but its more to minimise diesel knock in the cold engine. The automotive form of the Ford XLD is an indirect injected engine with glowplugs but it also kept them on at reduced power during the warm up, again to reduce the "diesel sound". I expect the latest automotive engines also use reduced power once the engine has started.

 

Anyway I was just trying to explain why river use can cause unexpected rises in consumption.

[johnandcharlie]

I'm new to all this, and still in the early stages of researching boats, but am surprised at the fuel consumption. The motorhome I currently live in has a 1.9TD engine and with it's trailer weighs over 3 tons. Overall I'm averaging 28mpg, and normally travel at about 45mph.

 

I assume a boat weighs a lot more, has a similar engine, but travels at less than a tenth of the speed. I also understand that one person can haul a boat a short distance with a rope, but I couldn't do that with my van, so I'd expect a boat to use far less fuel than my van, especially as it's doing not much more than tickover most of the time.

 

Why is fuel consumption so high?

[Athy]

J&C, I'm not a scientist, and I'm sure that someone with a better grasp of physics than mine, which would not be difficult, will give you a convincing answer. But I have always assumed that weight plays its part; the average narrowboat weighs between 10 and 15 tons as far as I'm aware, so it will require a lot of power to push it along.

[Proper Job]

J&C, I'm not a scientist, and I'm sure that someone with a better grasp of physics than mine, which would not be difficult, will give you a convincing answer. But I have always assumed that weight plays its part; the average narrowboat weighs between 10 and 15 tons as far as I'm aware, so it will require a lot of power to push it along.

It actually takes very little power to push a nb along - about 5 hp is the amount I've read somewhere. It takes a bit more to get it going and to stop it. But in real terms its not power; but torque applied to the propellor; which in turn produces thrust.

 

Compare the fuel consumption to that of a truck.... some of these struggle to do 5 - 6 mpg

[johnandcharlie]

It actually takes very little power to push a nb along - about 5 hp is the amount I've read somewhere. It takes a bit more to get it going and to stop it. But in real terms its not power; but torque applied to the propellor; which in turn produces thrust.

 

Compare the fuel consumption to that of a truck.... some of these struggle to do 5 - 6 mpg

So does that mean that the propeller is a very inefficient way to power a boat, most of the power is used to turn it, and very little is converted into propulsion?