Fuel Consumtion

[Machpoint005]

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?

Yup.

 

We do about 1.25 litres an hour, too (Beta 43, 48ft boat, say 1050 rpm cruise)

[Sheepshank]

It seems every car today comes equiped with computers to monitor fuel usage - does that technology ever get installed in narrowboats? Are there devices we can install to measure instantaneous and average consumption?

[Tony Brooks]

It seems every car today comes equiped with computers to monitor fuel usage - does that technology ever get installed in narrowboats? Are there devices we can install to measure instantaneous and average consumption?

 

 

Yes, but its specialist stuff. The car ones work from the length of the electrical injector pulse and use that to extrapolate the fuel delivered into the engine form the nozzle side, pressure and rpm. On our type of pumps you would need two flow meters for most engines. One measuring flow to the pump and one measuring the return to the tank. The meter would then have to subtract one from the other to find the flow into the cylinders.

[Sheepshank]

Yes, but its specialist stuff. The car ones work from the length of the electrical injector pulse and use that to extrapolate the fuel delivered into the engine form the nozzle side, pressure and rpm. On our type of pumps you would need two flow meters for most engines. One measuring flow to the pump and one measuring the return to the tank. The meter would then have to subtract one from the other to find the flow into the cylinders.

 

Tony, is it normal to have flow and return fuel lines? I can't check my set up at the moment, but I don't remmber it like that.

[chris w]

Tony, is it normal to have flow and return fuel lines? I can't check my set up at the moment, but I don't remmber it like that.

 

Definitely!

[Tony Brooks]

Tony, is it normal to have flow and return fuel lines? I can't check my set up at the moment, but I don't remmber it like that.

 

 

For most modern diesels yes - even if only to return the spill from the injectors, but most will also be returning far more fuel as well.

 

The Volvo Penta MD range did not have a return but it was susceptible to air if the system was the slightest bit unsound.

 

The modern stuff returns a lot of fuel from the top of the filter and the injector pump to not only bleed the odd air bubble back to the tank but also make them self bleeding.

[cotswoldsman]

Must say I have never kept record of the amount of fuel I use, I have always been happy to work on 1 litre per hour but guess after 01/11/08 I will have the record I hope it does not come as to much of a shock!!!!!

As I average about 1,000 hours a year and live on my boat cruising round the system all year the thought that I pay for that and all my lecy, hot water etc for less than £70 a month has always seemed like a great deal!!

[RobinJ]

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.

There are two types of deisel engine, direct and indirect.

Direct injection engines generally do not have heater plugs and the injectors squirt diesel direct into the cylinders, hence they usually have lower compression and often have de-comprerssion levers for starting.

Indirect injection engines have a small combustion chamber into which the fuel is squirted and also fitted with heater plugs, when firing all this gas has to pass through a relatively small hole into the cylinder, they usually have higher compression and are often sensitive to valve clearance .

[cotswoldsman]

There are two types of deisel engine, direct and indirect.

Direct injection engines generally do not have heater plugs and the injectors squirt diesel direct into the cylinders, hence they usually have lower compression and often have de-comprerssion levers for starting.

Indirect injection engines have a small combustion chamber into which the fuel is squirted and also fitted with heater plugs, when firing all this gas has to pass through a relatively small hole into the cylinder, they usually have higher compression and are often sensitive to valve clearance .

 

Wow all that gas , combustion and squirting going on right under my feet!!!!

Sometimes thinks it is better not to know!!

[bottle]

And the number of times a minute, it happens.

 

1,000 rpm.

[John Orentas]

The injector spill pipe cannot be termed as a 'return'. A true return and the system which we should all have on our boats will be a virtually full flow return back to the fuel tank.. The fuel should constantly flow around the circuit which includes the primary filter, only in this way will the fuel in the tank and everywhere else be constantly filtered and kept clean.

 

If he knew what he was looking for, even the owner of modern pretentious car would find within it a system as I have described.

Edited October 23, 2008 by John Orentas

[kayak]

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

 

 

 

 

What is it?

 

Pictures are nice!

 

I like pictures.

 

Kayak.

[wonderdust]

Nooooooooooooooooooo!

[Triton]

What is it?

 

Kayak.

Massey Ferguson ???

[carlt]

Probably a Jag. He lacks the imagination to go for anything more interesting (unless the missus picked it, of course).

 

At a guess.......weighing up the personality......XKR (poor man's Aston Martin).

[Railay]

We have a Lister HRW3 and seem to average about 1.8 ltrs per hour. This sounds high compared to many others but we are pulling a 22 ton 70ft narrowboat which is drawing 2ft 4in.

 

Does this compare with other similar sized boats out there?

 

On the subject of car consumption, I suggest you look at how much fuel you use per hour and then compare this to your boat, could prove very interesting??

 

Norman.

[Mick_B]

BMC 1.5, 27 ft plastic Elysian = 1.5 gallons per hour.

 

But every 40 min's or so the gallon bit goes back to the tank. Pity the pipe at the bottom of the tank was disconnected for the week..

[Tony Brooks]

And the number of times a minute, it happens.

 

1,000 rpm.

 

Yes, but on a four cylinder its 1000 rpm /2 = 500 rpm (because its a four stroke and every second rev is doing something different)

 

Then 500 x 4 (the number of cylinders) so that makes it 2000 times a minute at 1000 rpm.

 

 

See - I can do sums as well as the electrical chaps

[Justme]

On the subject of car consumption, I suggest you look at how much fuel you use per hour and then compare this to your boat, could prove very interesting??

 

Norman.

 

assuming 60mph & 40mpg

 

In one hour you will have traveled 60 miles & used 1.5 gallons or 6.675L at a rate of 9 miles per L.

 

So on L per hour it looks bad for the car but on L per mile it looks good.

 

Justme

[NB Alnwick]

I have calculated that 'Alnwick' uses an average of 1.9 litres of diesel an hour overall which includes cruising fast on tidal rivers and estuaries.

 

Of course only about 25% of that fuel is used for propulsion - the rest is used for keeping my feet warm, generating electrikery and other domestic purposes

[carlt]

Twin 128hp Ford Mermaids.....I daren't count!

[bottle]

Yes, but on a four cylinder its 1000 rpm /2 = 500 rpm (because its a four stroke and every second rev is doing something different)

 

Then 500 x 4 (the number of cylinders) so that makes it 2000 times a minute at 1000 rpm.

 

 

See - I can do sums as well as the electrical chaps

 

I didn't do the maths, to complicated.

[magnetman]

Beta Marine claim around 180-200 grams per HP per hour for their 38HP model and my little Lister LPW2 has 230g/HP/hr specific fuel consumption in the manual.

 

don't know if there is a 'rule of thumb' for this kind of thing but it makes sense most conventional diesel engines will be relatively similar.

[andywatson]

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.

 

1934 Gardner 3LW in 70ft x 2'10" draught >> 4 hrs/gall = 1.1 litres/hour.

[Boatgypsy]

Is this all related to how much we think we can get away with claiming is tax exempt when buying fuel? My 2.5 of course does .25 of a litre a day!