Engine Hours - What is a lot?

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asteven221

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I know this issue quite often pops up on this forum from time to time and there are differing opinions of what represents a lot of engine hours for our boat engines.

For no reason other than being curious I popped on to some trucking forums to see what they are saying about average mileage as we have marinised of truck engines installed in our boats.

It would appear that some of us are perhaps getting a bit too worked up about the number of engine hours we put on our engines. The average truck does 100,000 miles a year with many doing a lot more when they are on double shifts.

So as a rough estimate, if a truck is on a double shift which I assume is 2 x 8 hours, then that's over 4000 hours per annum. Some of these trucks are running for a fair number of years so it seems 30,000 to 40,000 hours isn't impossible over it's working life.

So by comparison, the 1300 hours on my Volvos would suggest they are just about brand new!
 
A Volvo truck D13 produces 500hp
A Volvo Penta D13 produces 900hp

If they could make a truck D13 produce 900hp and still keep going for many thousands of hours they would.
 
I had a cautious look a boat a couple of weeks ago as I've got a little itch to change mine, I've scratched it now and hope it's gone away. Anyway, I have 1200 ish hours on a 14 year old boat and the dealer told me that was a lot and would reduce the price regardless of service history :nonchalance:
 
KevB said:
I had a cautious look a boat a couple of weeks ago as I've got a little itch to change mine, I've scratched it now and hope it's gone away. Anyway, I have 1200 ish hours on a 14 year old boat and the dealer told me that was a lot and would reduce the price regardless of service history :nonchalance:
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That is a perceived market value rather than an engineering diagnosis though.
 
BruceK said:
That is a perceived market value rather than an engineering diagnosis though.
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Not even that.
It's purely dealer BS, aimed at selling something for the higher possible price while taking the partial exchange at the lower.
 
KevB said:
I had a cautious look a boat a couple of weeks ago as I've got a little itch to change mine, I've scratched it now and hope it's gone away. Anyway, I have 1200 ish hours on a 14 year old boat and the dealer told me that was a lot and would reduce the price regardless of service history :nonchalance:
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That's not even run in yet.
 
I have this rule of thumb - well for sailing boats anyway. Take the hours and multiply by 40 - a generous average speed for a diesel engine and you come to a nominal mileage.
Compare this with 100, 000 and make a decision based on that.

So, my boat has done 2,300 hours [ 25 years] that comes out at 92000 miles. I know that the oil has been changed every [200 x 40] 8000 miles or better, so I figure that I am good for a few more hours.
 
aquatom said:
A Volvo truck D13 produces 500hp
A Volvo Penta D13 produces 900hp

If they could make a truck D13 produce 900hp and still keep going for many thousands of hours they would.
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A VP D13 may well be capable of producing 900hp at WOT. How many people run it at that for more than VERY short bursts (if indeed at all) though?
 
Gwylan said:
I have this rule of thumb - well for sailing boats anyway. Take the hours and multiply by 40 - a generous average speed for a diesel engine and you come to a nominal mileage.
Compare this with 100, 000 and make a decision based on that.

So, my boat has done 2,300 hours [ 25 years] that comes out at 92000 miles. I know that the oil has been changed every [200 x 40] 8000 miles or better, so I figure that I am good for a few more hours.
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Much of those miles will be under sail with the engine turned off though, so a good proportion of those miles aren't relevant to the running of the engine (unless you're really averaging 40mph!)

With planing boats based on the coast the rule of thumb tends to be multiply by 10. So these 'high hour' boats with 2,000 hours on have typically covered about 20,000 miles.

No such thing as a 'high hour' leisure boat in reality, it's low hours/lack of use that kills them.
 
paul salliss said:
Gorgeous choice of words and correct. The dealer is a b shxxter
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Disagree. Most people would view a 2002 boat with 1,400 hours as 'high hours' and bid accordingly, as multiple threads on here show.

It absolutely isn't, but people seem to regard anything with over 1,000 hours as having 'gone round the clock'. Mad really.
 
I doubt many boat engines need replacing due to being worn out. There are 1000's of old diesels running perfectly well in older boats. More likely issues with under use and failing ancillaries that road vehicle equivalent don't have. Superchargers, cooling systems etc.

Anyway if you own a Volvo from about 1990 to 2005 ish I doubt you will need to worry about engine hours anyway as they simply dont work that often
 
I don't believe you can all ways go on hours as something used regularly is better than something seldom used.
Also engines that haven't done any work sometimes have had less maintaince due to hardly done an hours or work this season ect.

Also I know a techie on plant, mainly cat and he says they don't even oil and filter them till every 1000 hours due to how much work they do.

Yes I know it's different work & rpm but it's all relative.

The thing with boats that have done a few hours & are older is fatigue normally takes over.
 
ari said:
A VP D13 may well be capable of producing 900hp at WOT. How many people run it at that for more than VERY short bursts (if indeed at all) though?
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That's true, but the D13 boat engine running 1800rpm still pulls close to 500hp which is max power for the truck engine. In reality truck engine spends a lot of time at 1200-1300rpm cruising on motorway pulling nowhere near 500hp.
 
ari said:
Disagree. Most people would view a 2002 boat with 1,400 hours as 'high hours' and bid accordingly, as multiple threads on here show.

It absolutely isn't, but people seem to regard anything with over 1,000 hours as having 'gone round the clock'. Mad really.
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Its the same people who think a car grinds to a halt at 100,000 miles

In fact that probably drives the 1,000 hours arbitrary figure - it looks a bit like 100,000 dunnit...
 
I don't think you can compare with road vehicles, the load characteristics on the engine are completely different.

A marine engine has to work pretty hard to achieve decent turns of speed, these extra loads surely have to be calculated into the equation.

Think about which marine engines are used in automotive applications and compare the fuel consumption data. Ie a chevy v8 in your average 2tonne sportscruiser consumes 7-10 gph at say 20knots. The same engine in say a Chevrolet suburban (huge American 4x4) which weighs about 2-3 tonnes at say 50mph will return at least 20mpg. So which engine is working harder for a relative period of time?
 
This couple on their 52' Nordhavn have so far put 7,300 hrs on their John Deere main engine (they also have a small wing engine) during their voyage around the world, and I am sure that this engine will happily do another 7,000 without fanfare if it is looked after sensibly.
http://www.nordhavn.com/news/headlines/3600_passage/

Many of the commercial fishing vessels here in Barbados have John Deere engines, and most of them average around 1,500 hours of use every year.
And some of these engines are almost 20 years old now.......
 
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