DavidJ
Well-Known Member
How did you get to that from the Volvo site. I'm interested in KAD43 but get the pdf brochure only, no graphs.
David
David
Fuel consumption
- Thread starter adrianm
- Start date
Divemaster1
Well-Known Member
[ QUOTE ]
How did you get to that from the Volvo site. I'm interested in KAD43 but get the pdf brochure only, no graphs.David
[/ QUOTE ]
Looks like the graph is not included in the "newer" engines ... will do some research & come back to you ...
How did you get to that from the Volvo site. I'm interested in KAD43 but get the pdf brochure only, no graphs.David
[/ QUOTE ]
Looks like the graph is not included in the "newer" engines ... will do some research & come back to you ...
Anchorite
Well-Known Member
JEG: one of your factors is way out...your 10 tonnes boat should have a motor of say 50 - 75 HP (rough guide for displacement boats: 5 HP/tonne). Even with oversized engine your figure of 5l/hour will be about right...I would have guessed 7-8 l/hr max if sea rough. For comparison my 8 tonne boat at hull speed (7 knots) with 35HP BMC uses 4 - 5 l/hr.
Trying to work out from the MOBO graphs won't help - they are based on motor/prop/boat all being correctly matched (not your case /forums/images/graemlins/blush.gif). You will need maybe 30HP (22.5 kwh) at cruising speed, even if at 3000 revs this will still only burn 22.5 x 240 grammes = 5 litres/hour /forums/images/graemlins/cool.gif.
Trying to work out from the MOBO graphs won't help - they are based on motor/prop/boat all being correctly matched (not your case /forums/images/graemlins/blush.gif). You will need maybe 30HP (22.5 kwh) at cruising speed, even if at 3000 revs this will still only burn 22.5 x 240 grammes = 5 litres/hour /forums/images/graemlins/cool.gif.
JEG
Well-Known Member
Anchorite,
No doubt you are right about general hp requirements; I understand that naval architects use 4 hp per ton for displacement speed. The boat was purchased second hand & the previous owners were German [very decent people] but, as the Dutch broker said to me "the Germans like power" - double meaning intended I think.
No doubt you are right about general hp requirements; I understand that naval architects use 4 hp per ton for displacement speed. The boat was purchased second hand & the previous owners were German [very decent people] but, as the Dutch broker said to me "the Germans like power" - double meaning intended I think.
andyball
Well-Known Member
we use 5l/h @ 5 or 6 knots on a Gruno 38 - about 11 tonnes & similarly overpowered/underpropped, albeit a heavier 6.2l ford w/o turbo.
Will one day think about more pitch,to give lower rpm, but the prop. opening is rather small & already has a 4-blade one @ 22x14 (I think)
I think using 1800 for cruise is a bit high - wouldn't care for 3000 - but you must have some spare space over a big ford.
Will one day think about more pitch,to give lower rpm, but the prop. opening is rather small & already has a 4-blade one @ 22x14 (I think)
I think using 1800 for cruise is a bit high - wouldn't care for 3000 - but you must have some spare space over a big ford.
JEG
Well-Known Member
Hi Andy,
I'm more confused than ever! I thought that one needed to work the engine to around 75% of revs in order to avoid bore glazing. An owner of the same model as mine, but with a 200 hp tamd41b said that he runs at 3000 rpm & the volvo handbook advises cruising @ 200 below max, i.e. 3600 rpm.
I'd best sit in the corner wearing my dunce's cap.
John G
I'm more confused than ever! I thought that one needed to work the engine to around 75% of revs in order to avoid bore glazing. An owner of the same model as mine, but with a 200 hp tamd41b said that he runs at 3000 rpm & the volvo handbook advises cruising @ 200 below max, i.e. 3600 rpm.
I'd best sit in the corner wearing my dunce's cap.
John G
andyball
Well-Known Member
ours has over 2000h clocked w/o problems.
Think every car/truck diesel wd be glazed if 75% of revs were needed to avoid it - that'd be very fast on many modern saloon diesels.
& london buses must spend forever idling, then working briefly.....
Our motor is available in leisure & commercial spec - commercial seems to be just limiting the revs to 1500 where it still produces 70-80 hp which is enough for me - We often run at that speed anyway, just that a knot or two more for same rpm wd be welcome. But 22" bronze prop's being what they are ( expensive) I can't justify it on grounds of fuel consumption.
Ford 2725's for industrial,commercial & low speed generators are mainly governed to 1500 .
I'd expect no problems if you run at whatever speed produces 6 knots or so, even if that is much lower than 3000.
do you have a problem with fuel useage? or just interested.
As others have said, but some of the calculations in this thread have ignored - just cos a motor runs at xxx rpm doesn't mean it's producing the
power it's capable of at that speed - any more than running your car engine at 3000rpm in neutral or downhill uses the same fuel as 3000rpm up a steep hill. On a diesel - the lever sets the speed & the injector pump/electronics provide enough fuel to maintain that speed. So at 3000rpm you might use 5+galls/h or a tiny fraction of that. eg on my boat 1500rpm could produce say 70hp, but at that rpm I use 1 gall/h not the 3+ that the hp graph may suggest. Proper fuel consumption figures from manufacturers show BSFC - Brake specific Fuel consumption (I think) in lbs per hp per hour or grams per KW per hour.
Think every car/truck diesel wd be glazed if 75% of revs were needed to avoid it - that'd be very fast on many modern saloon diesels.
& london buses must spend forever idling, then working briefly.....
Our motor is available in leisure & commercial spec - commercial seems to be just limiting the revs to 1500 where it still produces 70-80 hp which is enough for me - We often run at that speed anyway, just that a knot or two more for same rpm wd be welcome. But 22" bronze prop's being what they are ( expensive) I can't justify it on grounds of fuel consumption.
Ford 2725's for industrial,commercial & low speed generators are mainly governed to 1500 .
I'd expect no problems if you run at whatever speed produces 6 knots or so, even if that is much lower than 3000.
do you have a problem with fuel useage? or just interested.
As others have said, but some of the calculations in this thread have ignored - just cos a motor runs at xxx rpm doesn't mean it's producing the
power it's capable of at that speed - any more than running your car engine at 3000rpm in neutral or downhill uses the same fuel as 3000rpm up a steep hill. On a diesel - the lever sets the speed & the injector pump/electronics provide enough fuel to maintain that speed. So at 3000rpm you might use 5+galls/h or a tiny fraction of that. eg on my boat 1500rpm could produce say 70hp, but at that rpm I use 1 gall/h not the 3+ that the hp graph may suggest. Proper fuel consumption figures from manufacturers show BSFC - Brake specific Fuel consumption (I think) in lbs per hp per hour or grams per KW per hour.
Divemaster1
Well-Known Member
[ QUOTE ]
..........As others have said, but some of the calculations in this thread have ignored - just cos a motor runs at xxx rpm doesn't mean it's producing the
power it's capable of at that speed -...........
[/ QUOTE ]
Quite correct there .... all calculations above at given RPM are based upon the fact that the engine actually reaches full load at max RPM and is not governed in any way.
If the engine produces (engine load) is 35 HP at 3000 RPM, then the calculations should be done for 35 HP... However, in JEG's case, it is difficult to determine what HP is extracted at this RPM. Linsen should be capable of telling JEG this, or at least provide the expected figures, if not the actual.
With respect to life expectancy at lower RPM, I would not worry at all. A modern diesel will run very well for 1000's of hours if not stressed. @ 1500 - 3000 RPM on this engine, which sounds under propped, I would not worry about glazing or having excess carbon buildup... That stuff mostly relates to the older engines, and in particular 2 - stroke diesels (which I have).
..........As others have said, but some of the calculations in this thread have ignored - just cos a motor runs at xxx rpm doesn't mean it's producing the
power it's capable of at that speed -...........
[/ QUOTE ]
Quite correct there .... all calculations above at given RPM are based upon the fact that the engine actually reaches full load at max RPM and is not governed in any way.
If the engine produces (engine load) is 35 HP at 3000 RPM, then the calculations should be done for 35 HP... However, in JEG's case, it is difficult to determine what HP is extracted at this RPM. Linsen should be capable of telling JEG this, or at least provide the expected figures, if not the actual.
With respect to life expectancy at lower RPM, I would not worry at all. A modern diesel will run very well for 1000's of hours if not stressed. @ 1500 - 3000 RPM on this engine, which sounds under propped, I would not worry about glazing or having excess carbon buildup... That stuff mostly relates to the older engines, and in particular 2 - stroke diesels (which I have).
JEG
Well-Known Member
Hi Andy,
No problems with fuel usage [unless I find out it's 40 gallons an hour], mere curiousity combined with the need to know for the safety aspect.
Thanks for your interesting & helpful contribution.
John G
No problems with fuel usage [unless I find out it's 40 gallons an hour], mere curiousity combined with the need to know for the safety aspect.
Thanks for your interesting & helpful contribution.
John G
JEG
Well-Known Member
Gentlemen,
Thank you all for your contributions - I'll ask Linssen when I go to their annual show in December.
John G
Thank you all for your contributions - I'll ask Linssen when I go to their annual show in December.
John G
MapisM
Well-Known Member
It\'s not the tourist, ...
... it's the company doing business with those ferries, who is in a hurry!
The fuel cost is just one part of the game.
Other major costs are the crew and the depreciation of the vessel.
A ferry capable of a return trip in the same time another one covers just a one way route, has two advantages:
1) double earnings;
2) same amount of the above "fixed" costs.
Which can more than compensate the higher fuel costs.
We're living in a world where companies are not just asked to be profitable - they must be QUICKLY profitable.
Does this mean also capable of surviving in the long term?
I'm not sure, but apparently that's not a major concern for most shareholders and banks.
... it's the company doing business with those ferries, who is in a hurry!
The fuel cost is just one part of the game.
Other major costs are the crew and the depreciation of the vessel.
A ferry capable of a return trip in the same time another one covers just a one way route, has two advantages:
1) double earnings;
2) same amount of the above "fixed" costs.
Which can more than compensate the higher fuel costs.
We're living in a world where companies are not just asked to be profitable - they must be QUICKLY profitable.
Does this mean also capable of surviving in the long term?
I'm not sure, but apparently that's not a major concern for most shareholders and banks.