engine hours

[ayeaye]

know your going to think this is a silly qeustion bit like how longs a piece of string but could anyone give me a rough idea of how many hours a Vetus 4.15 would run for on a gallon or gallons of diesel trying to find out roughly the consumtion as the sailaway we have got doesn't as yet have a diesel gauge ta Bren

[John Orentas]

The usual sort of consumption at canal speeds is about 3 hours per gallon of diesel though on rivers this can increase to a frightening degree. Don't bother with fuel gauges, just sort out a crude dip-stick or with many boats you can simply see the fuel level through the filler.

[David Schweizer]

My BMC 1.5 does marginally less than one litre per hour on Canals, and about 1.5 litres per hour upstream on the Thames.

[ayeaye]

My BMC 1.5 does marginally less than one litre per hour on Canals, and about 1.5 litres per hour upstream on the Thames.

Many thanks to both of you, next job to create a dip stick. Bren

[bottle]

Many thanks to both of you, next job to create a dip stick. Bren

 

A broom stick will do it.

[David Schweizer]

A broom stick will do it.

To use a dip stick in my fuel tank would require me to drill a hole in the top of the Tank and remove the shelf above the tank. My tanks are inside tha swims with the engine between them, and the filler is on the gunwahle with a cranked filler pipe. One of the main reasons why I keep a close watch on engine hours to ensure that I do not run out of fuel.

[bottle]

To use a dip stick in my fuel tank would require me to drill a hole in the top of the Tank and remove the shelf above the tank. My tanks are inside tha swims with the engine between them, and the filler is on the gunwahle with a cranked filler pipe. One of the main reasons why I keep a close watch on engine hours to ensure that I do not run out of fuel.

 

Ah! a bendy broomstick then

 

The only tanks I have seen it was possible to use one

[Alastair]

The rule of thumb is 10hp per litre per hour. Slightly less for turbo-charged engines.

 

The hp isn't the hp of the engine, but what hp you are using at the time. This is possible to work out from power curves for your engine.

 

My 90hp merc uses 5l per hour at a cruising speed of 5kt, so the formula seems to be about right.

[mr toad]

My boat is similar to this it has a cranked fuel filler, however the vent pipe is straight so i remove the vent plug and use a garden cane.

[NB Willawaw]

The most economical speed for the M4.15 is 1800rpm approx.

Its supposed to burn 6.1Kg diesel per hour at that speed.

Anybody know the mass of diesel fuel ?

[ChrisPy]

Don't bother with fuel gauges, just sort out a crude dip-stick or with many boats you can simply see the fuel level through the filler.

I agree 100%.

 

Big working boats don't have gauges, its only a luxury gadget for narrowboats. I worked on a 200 passenger trip boat on the River Dart and we just used a dipstick. In those days it was like an old fashioned carpenter's rule, it was made of boxwood and had to be about 10feet long to dip the enormous tanks.

[JohnOnTheWey]

The most economical speed for the M4.15 is 1800rpm approx.

Its supposed to burn 6.1Kg diesel per hour at that speed.

Anybody know the mass of diesel fuel ?

 

The density of diesel fuel varies (for some reason I can't fathom at the moment but someone will know - different grades I suppose) between 820 and 950 Kg/cu.m. So, taking the average as 885, that means that 6.1 Kg = 6.1*1000/885 litres = 6.9 litres, or thereabouts.

 

... errr - is that right?

 

John

[NB Willawaw]

No its doesn't sound right.

Vetus quote the consumption as 185g per hp.h or 252g/KW.h and the M4.15 is a 32/33HP engine.

Are my maths suspect ?

[ayeaye]

No its doesn't sound right.

Vetus quote the consumption as 185g per hp.h or 252g/KW.h and the M4.15 is a 32/33HP engine.

Are my maths suspect ?

Gosh all these maths I'm def lost now, we were out on the boat last week-end, Vetus reccomend for first 50 hours running in to stick to 1,000 revs our boat is only 40 foot & I cant see that we could use many more revs than that as I reckon we were doing 4 mph at 1,000, though I know you need more to get you out of bother, but if we cruised at 1800 revs I'm sure we'd become a flying machine. thanks all of you your so helpfull Bren

[Billypownall]

Gosh all these maths I'm def lost now, we were out on the boat last week-end, Vetus reccomend for first 50 hours running in to stick to 1,000 revs our boat is only 40 foot & I cant see that we could use many more revs than that as I reckon we were doing 4 mph at 1,000, though I know you need more to get you out of bother, but if we cruised at 1800 revs I'm sure we'd become a flying machine. thanks all of you your so helpfull Bren

Are you sure about keeping your Vetus to 1000 r.p.m. Ayeaye ? Sounds aginst all I have been told about modern high reving diesel engines. First all all if you are going to be doing 4 m.p.h. at 1000 your boat is going to be very over propped. You should be aiming for at least 1500 revs giving you 4 m.p.h. otherwise your engine will be labouring all the time and it will cetainly not like it in the long run A further important downside will be that your alternator will only be operating at about half its potential output. It may seem nice to have an engine just ticking over all the time but it will run a lot better with a few revs on and your batteries will like it better too.

[John Orentas]

1,000 rpm at 4 mph sounds about right to me, in a wide deep canal anyway, but of course it all depends on what engine you have. The alternator speed does not really come into it, the manufacture will 'gear' it to suit the cruising speed of the engine.

 

The inbuilt regulator will take care of the charge rate of the alternator virtually regardless of it's speed.

[Billypownall]

1,000 rpm at 4 mph sounds about right to me, in a wide deep canal anyway, but of course it all depends on what engine you have. The alternator speed does not really come into it, the manufacture will 'gear' it to suit the cruising speed of the engine.

 

The inbuilt regulator will take care of the charge rate of the alternator virtually regardless of it's speed.

I respect what you say John of course as I am no expert but my Vetus 90 amp alternator produced 25 amp at 1000 r.p.m. and 70 amp at 1500 r.p.m.I am thinking therefore that Vetus must gear their alternators to a cruising speed of about 1500 r.p.m. I repropped the boat on Vetus advice from a 17 x 12 to a 17 x 10. The engine was much smoother and no noisier with the increase in revs. Flat battery problems completely disappeared. Peak r.p.m. with the larger prop was only 2600 or so instead of the rated maximum of 3000 which it now attains.

[bottle]

The inbuilt regulator will take care of the charge rate of the alternator virtually regardless of it's speed.

 

I don't think so, if this is true why do all engine manufacturers 'overdrive' the domestic alternator to increase its output when the engine is turning at low revs.

 

All engines have a 'sweet' speed usually at approx max torgue, I would guess that the ideal speed to travel through the water would be at that point, this would be at approxiamately 4mph in the ideal world.

[John Orentas]

I don't think so, if this is true why do all engine manufacturers 'overdrive' the domestic alternator to increase its output when the engine is turning at low revs.

 

All engines have a 'sweet' speed usually at approx max torgue, I would guess that the ideal speed to travel through the water would be at that point, this would be at approxiamately 4mph in the ideal world.

 

 

I really don't know where you chaps get your information, I suspect more from supposition that anything else. I have gone to a lot of trouble over the years measuring and testing. I suggest you acquire some instrumentation and do the same.

[bottle]

 

I don't think so, if this is true why do all engine manufacturers 'overdrive' the domestic alternator to increase its output when the engine is turning at low revs.

 

All engines have a 'sweet' speed usually at approx max torgue, I would guess that the ideal speed to travel through the water would be at that point, this would be at approxiamately 4mph in the ideal world.

 

 

I really don't know where you chaps get your information, I suspect more from supposition that anything else. I have gone to a lot of trouble over the years measuring and testing. I suggest you acquire some instrumentation and do the same.

 

John

 

Perhaps I should have punctuated my post better, the 'I don't think so' was a throw away line and there should have been a ? at the end.

 

The second sentence is from experience of engines they do have a 'sweet spot' and 'I would guess that the ideal speed to travel through the water would be at that point, this would be at approxiamately 4mph in the ideal world.'

 

I am guessing.

 

I will always bow to a greater knowledge than my own.

[Billypownall]

I really don't know where you chaps get your information, I suspect more from supposition that anything else. I have gone to a lot of trouble over the years measuring and testing. I suggest you acquire some instrumentation and do the same.

I trust these remarks do not apply to my previous comment which was based on instrumentation and certainly not supposition. Giving further thought to doing 4 m.p.h. at 1000 r.p.m. This would seem to indicate(True with supposition!!) that tickover speed,840 r.p.m.recommended by Vetus,would give close to 3 m.p.h.far too fast for passing moored craft. Far nicer to be passing these at about 950 r.p.m. and a little over 2 m.p.h. (according to my g.p.s. not supposition)

[ayeaye]

I trust these remarks do not apply to my previous comment which was based on instrumentation and certainly not supposition. Giving further thought to doing 4 m.p.h. at 1000 r.p.m. This would seem to indicate(True with supposition!!) that tickover speed,840 r.p.m.recommended by Vetus,would give close to 3 m.p.h.far too fast for passing moored craft. Far nicer to be passing these at about 950 r.p.m. and a little over 2 m.p.h. (according to my g.p.s. not supposition)

I do find we're going to fast for moored boats we have to put it out of gear before we get to them maybe a smaller prop would be the answer Bren

[DHutch]

Oh my god, John are still going on about alternator speed not affecting charge rate!

- We've covered this about 5times, and everytime we have come to the conclution that the speed the alternator is turning can, and does, affect the charge output of the alternator on a large number of setups. Nuff said.

 

 

Daniel

[Guest]

I respect what you say John of course as I am no expert but my Vetus 90 amp alternator produced 25 amp at 1000 r.p.m. and 70 amp at 1500 r.p.m.I am thinking therefore that Vetus must gear their alternators to a cruising speed of about 1500 r.p.m. I repropped the boat on Vetus advice from a 17 x 12 to a 17 x 10. The engine was much smoother and no noisier with the increase in revs. Flat battery problems completely disappeared. Peak r.p.m. with the larger prop was only 2600 or so instead of the rated maximum of 3000 which it now attains.

Our Vetus 415 is propped at 17x10 on a 57NB. I have no ammeter, but find that little charge is put into the batteries at below 1200rpm. At 1300 rpm the voltmeter increases significantly which is the setting we use for battery charging.