Cost per hour of running engine

[kev_rm]

Assuming something in the 30-50hp range, I am coming up with about US$13/hour, any comments?

Fuel GPH 1.5
Fuel Cost Per Hour 6
Oil Change, Each 50
Oil Change, Hours 150
Oil Cost Per Hour 3
Fuel Filter Change, Each 20
Fuel Filter Hours 50
Fuel Filter Cost Per Hour 2.5
Engine Lifetime Hours 8000
Engine Cost 10000
Engine Misc Repairs 1500
Engine Cost Per Hour 1.4375
Total Engine Cost/hr 12.9375 PER HOUR

[a64pilot]

You can play around with the numbers as of course prices will vary, but that’s about how we come up with the cost to operate an aircraft engine.
Biggest costs are usually overhaul and fuel.
I think you have the gist of it. It costs more than people want to believe, they tend to think only in fuel.

[newhaul]

Originally Posted by kev_rm

Assuming something in the 30-50hp range, I am coming up with about US$13/hour, any comments?

Fuel GPH 1.5
Fuel Cost Per Hour 6
Oil Change, Each 50
Oil Change, Hours 150
Oil Cost Per Hour 3
Fuel Filter Change, Each 20
Fuel Filter Hours 50
Fuel Filter Cost Per Hour 2.5
Engine Lifetime Hours 8000
Engine Cost 10000
Engine Misc Repairs 1500
Engine Cost Per Hour 1.4375
Total Engine Cost/hr 12.9375 PER HOUR

engine hours more likely 10k between rebuilds .
First rebuild will cost about 1/3 of original engine cost with 8 k till next major overhaul
So the 20 year cost is much lower per hour of operation

Just one question how many people would change a fuel filter after 75 gallons of fuel ?

[john61ct]

Yes not just overhauls, but with modern diesels especially if anti-pollution measures mandated, regular maintenance intervals can really add up too.

[Jim Cate]

Originally Posted by kev_rm

Assuming something in the 30-50hp range, I am coming up with about US$13/hour, any comments?

Fuel GPH 1.5
Fuel Cost Per Hour 6
Oil Change, Each 50
Oil Change, Hours 150
Oil Cost Per Hour 3
Fuel Filter Change, Each 20
Fuel Filter Hours 50
Fuel Filter Cost Per Hour 2.5
Engine Lifetime Hours 8000
Engine Cost 10000
Engine Misc Repairs 1500
Engine Cost Per Hour 1.4375
Total Engine Cost/hr 12.9375 PER HOUR

Well, I get oil cost at 50/150= .33$/hr, not 3$/hr.

And your fuel costs seem to be based on running the engine near flat out all the time which is unrealistic. Eg, our 43 hp engine has averaged only 2.5 liters/hour throughout its life so far, including battery charging, idling through anchorages and some relatively high speed runs (rare).

Oil filters don't seem to be included.

Fuel filters are not typically changed on a 50 hour schedule.

And the miscellaneous repair figure is totally arbitrary... could be high, could be way low.

So, while I agree that engine running costs more than we usually imagine, your figures are a bit pessimistic IMO.

Jim

[model 10]

[QUOTE=a64pilot;2919718]You can play around with the numbers as of course prices will vary, but that’s about how we come up with the cost to operate an aircraft engine.


Yeah but you need to ovhl an aircraft engine on a schedule so it's a bit more easy to figure costs. It might be 20 years before I need another hot section on my boat engine.

[Kenomac]

Our cost is less than half for a 100hp turbo. Fuel burn 4 liters per hour at .62 cents per liter. Oil change once per season done ourselves and fuel filter once every couple of years by self when needed, which is rare because fuel is polished regularly onboard.

[Fuss]

change the fuel filters when they need it, it can’t be factored into a service, that’s why you have 2 so you can immediately swap in case of trouble

[jimbunyard]

Think you got your division backwards a coupla times.

Fuel GPH............................1.5
Fuel Cost Per Hour...............6

Oil Change, Each...............50
Oil Change, Hours............150
Oil Cost Per Hour.................3

Should be .33/hr

Fuel Filter Change, Each.....20
Fuel Filter Hours................50
Fuel Filter Cost Per Hour.......2.5

Should be .40/hr

Engine Lifetime Hours.....8000
Engine Cost..................10000
Engine Misc Repairs.........1500
Engine Cost Per Hour.............1.4375

Total Engine Cost/hr.............12.9375 PER HOUR

Should be 8.1675/hr


To compare with my 20 hp Volvo

Fuel GPH................................ .25 gal/hr
Fuel Cost Per Hour................... 1.25/hr

Oil Change, Each...................21
Oil Change, Hours................150
Oil Cost Per Hour..................... .14/hr

Fuel Filter Change, Each..........20
Fuel Filter Hours...................200
Fuel Filter Cost Per Hour............ .10/hr

Engine Lifetime Hours..........4000 (estimated since I
Engine Cost.........................650.00 bought used)
Engine Misc Repairs..............250.00 (so far, 6 years)
Engine Cost Per Hour................. .225/hr

Total Engine Cost/hr.................. 1.715 PER HOUR

Just for grins...

[DefinitelyMe]

Interesting. Thanks for posting all this guys. One question: are you really burning 1.5 gal/h diesel?! Our old 40hp Westerbeke goes through an average of 0.4 gal/h. No charging runs, only for propulsion.

[kev_rm]

Oops, corrected math, updated based on some feedback

Fuel GPH 0.6
Fuel Cost Per Hour $2.40
Oil Change, Each 50
Oil Change, Hours 150
Oil Cost Per Hour $0.33
Fuel Filter Change, Each 20
Fuel Filter Hours 500
Fuel Filter Cost Per Hour $0.04
Engine Lifetime Hours 10000
Engine Cost 10000
Engine Misc Repairs 1500
Engine Cost Per Hour 1.15
Total Engine Cost/hr $3.92 PER HOUR

[skipperpete]

Add $1/hr for the gearbox if it's a Hurth, they have trouble surviving past 3000 hours and a replacement with a drive plate and labour is over 3K$.
It might be more for an SD 50 saildrive or a borg warner velvetdrive.

[a64pilot]

[QUOTE=Ecos;2919803]

Originally Posted by a64pilot

You can play around with the numbers as of course prices will vary, but that’s about how we come up with the cost to operate an aircraft engine.


Yeah but you need to ovhl an aircraft engine on a schedule so it's a bit more easy to figure costs. It might be 20 years before I need another hot section on my boat engine.

No you don’t. You only need to follow TBO if the aircraft is used for flight training or for carrying passengers for hire, part 91 operators don’t need to TBO.

Interestingly it’s been followed for decades, following TBO does not increase safety nor decrease engine failures, so why aren’t all engines “On condition”
Would you believe that large Commercial aircraft don’t TBO either, they are on condition?

But determining cost per hour is a planning thing, it’s not necessarily reality, it’s just a smart person trying to figure out how much does it really cost, and it’s the best estimate.
A prop strike for example throws the estimate out of the window, as can many other things. Hot start for a turbine for example.

TBO is more of a warranty thing now, there are even many STC’s that can greatly extend TBO’s which I cannot understand, that shouldn’t be allowed in my opinion.

This is US rules of course, other countries may vary, for instance most Latin American countries require part 137 (Ag) operators to follow TBO, the US does not

[newhaul]

Originally Posted by skipperpete

Add $1/hr for the gearbox if it's a Hurth, they have trouble surviving past 3000 hours and a replacement with a drive plate and labour is over 3K$.
It might be more for an SD 50 saildrive or a borg warner velvetdrive.

rebuild kits range from 300 to 800 USD depending on model and are easily overhauled . Just follow the manual.
New clutch pack kits are cheaper .

[Dockhead]

Originally Posted by Kenomac

Our cost is less than half for a 100hp turbo. Fuel burn 4 liters per hour at .62 cents per liter. . . .

Where do you buy fuel for $0.62 per liter (or is it €0.62)? I want some of that.


That's less than half of what it costs around here.