MAN 800 engines....

[MapisM]

Ok, that sounds familiar.
All heat exchangers (engines and gearboxes) and aftercoolers of my boat are being cleaned as I'm writing.
I was actually curious about the 5 years interval that you mentioned, is it specified in R6 service manual?
Afaik, MAN recommendation for V engines is either 200 hours or 2 years, whatever comes first.
A deadline which in my experience even MAN official dealers don't dare recommending, actually.
Most of them agree that 4 years regardless of hours is a sensible timing.

You are making me curious about the oil cooler gasket, though.
That's not something I've ever heard to be a problem, in V engines.
I don't even know where it is, in fact...
If you could elaborate a bit more, I for one am interested, TIA!

 

[pan]

The Man R800 service schedule details a 5yr major service (ie, not just oils/filters etc), the engine oil cooler is located low down behind the heat exchanger, the gasket is a simple 'card' type, but the connecting bolts are not evenly spaced and the gaskets can fail, engineers usually just visually inspect for leaks, they didn't see anything, but one failed 3 hrs after the above service. I would definately replace during this service, as it's expensive to do after the cooling equipment is re-fitted!

 

[Chris H]

So it’s not recommend to drop the oil and change filters each year as a minimum

 

[PowerYachtBlog]

The l/nm numbers from PYB are positively related to total fuel burn, it would be out of this world if that boat would burn 15 l/nm.
They are slightly worse than I expected in my first post, btw.
In fact, slightly worse than in my much heavier boat with the same power V8 engines, but still within reason.
The only thing which is bound to be wrong is the comparison with the Cayman, because 7.6 l/nm is obviously worse than 7.2 l/nm, not better.
Maybe PYB just swapped the numbers, 'dunno.

It is for both engines. Cayman is a bit worse and should be, it is a heavier two to three ton boat, with a deeper more even keel.
But the Cayman had a better prop delivery in the sense that at 1900 rpm the R6's drink 95 lph per engine. These where the original Radice propellers which where a bit pitted by the way.
190 lph total divide by 25 knots equals 7.6 liter per nautical mile. R6 Mans at 1920 rpm.
The Sunseeker burnt 180 liters at 25 knots which equals 7.2 liter per nautical miles. R6 Man at 1800 rpm. The Sunseeker though at 1900 rpm goes over 100 liter per hour per engine.

The propeller load according to the manual can vary a lot in these boats, from 60 lph to 100 lph per engine.

 

[pan]

So it’s not recommend to drop the oil and change filters each year as a minimum

No, it is part of the service schedule to do oil change etc each year.

 

[Eren]

Ok, that sounds familiar.
All heat exchangers (engines and gearboxes) and aftercoolers of my boat are being cleaned as I'm writing.
I was actually curious about the 5 years interval that you mentioned, is it specified in R6 service manual?
Afaik, MAN recommendation for V engines is either 200 hours or 2 years, whatever comes first.
A deadline which in my experience even MAN official dealers don't dare recommending, actually.
Most of them agree that 4 years regardless of hours is a sensible timing.

You are making me curious about the oil cooler gasket, though.
That's not something I've ever heard to be a problem, in V engines.
I don't even know where it is, in fact...
If you could elaborate a bit more, I for one am interested, TIA!

When it comes to servicing calendar, manufacturers stay on the very safe side. I would actually do the same if I was in their seats. You make your client keep the engines at their healthiest state, you protect and increase the reputation of your brand and finally, you sell lots of spare parts.

However with some knowledge and common sense, it is possible to spend more sensibly on the maintenance and still keep your engines as much healthy. Cleaning of coolers is an example to this. The coolers do not break in one day. They show their signs much much earlier. The normal working temperatures begin to increase by one or two degrees. If you have digital gauges at your boat, you can immediately see this. Or the temps keeps on increasing and do not stabilize at one point when you push the engines hard. A careful skipper who follow the regular data of his engines will immediately feel these differences and will do the necessary cooler servicing when needed, not 2 years earlier than needed.

Secondly, it is not always needed to dissasamble the cooler to clean it physically. It is also possible to clean it chemically by flushing it without disassabling. This saves you the costs of the gaskets, which are actually quite expensive at MAN, plus a lot of man-hours Of course once in a while, the gaskets should be changed as well.

All in all, service schedules is a good guide, but they can also be adjusted as per your usage of the boat, with some knowledge and common sense.

 

[pan]

Totally agree Eren... however when selling a quite expensive asset prospective purchasers prefer to see 'manufacturers' service schedules complete and are likely to pay more than on other boats without, more than covering the extra servicing costs. Just how the market is.

 

[Eren]

Totally agree Eren... however when selling a quite expensive asset prospective purchasers prefer to see 'manufacturers' service schedules complete and are likely to pay more than on other boats without, more than covering the extra servicing costs. Just how the market is.

Well I agree and disagree... In the recent years I sold two boats, one was 47 feet and the other 64. Prinny 64 was priced above a million quids, so it is really serious amount which needs all kinds of investigation before buying. For the 47 footer there was a "clown" who was brought in as a "surveyor". For the other one, there was a better surveyor but in both cases the broker was "very very fast" in finding replies/excuses for any kind of minor faults, as he wants the deal to be finished and get his commission. Funnily, I was surprised to see how buyers would like to hear only the good things about the boat. When they were coming to the boat that morning, they already had the dreams flying in the air about how they will enjoy the summer with that boat. So buyers are also very impatient at such situations. On my side I was more than comfortable because I knew that my boats were tip top, even though may be I could not prove that all servicing was done up to the manufacturer's service schedule. My engines would pass any tests and checks that a manufacturer's service guy could do. All in all, you may miss one-two potential buyers because of service history, but there are many more who either doesn't understand anything at all, or are knowledgable enough to understand what they see/check. Most of the wise and knowledgable characters here in this forum are unique and rare to find.

 

[MapisM]

However with some knowledge and common sense, it is possible to spend more sensibly on the maintenance and still keep your engines as much healthy. Cleaning of coolers is an example to this. The coolers do not break in one day. They show their signs much much earlier. The normal working temperatures begin to increase by one or two degrees. If you have digital gauges at your boat, you can immediately see this. Or the temps keeps on increasing and do not stabilize at one point when you push the engines hard. A careful skipper who follow the regular data of his engines will immediately feel these differences and will do the necessary cooler servicing when needed, not 2 years earlier than needed.

Actually, in my experience it's much more tricky to estimate the heat exchangers conditions based on the cooling liquid temperature alone.
There are in fact several other factors, that can be more or less relevant, but whose effect is hard to distinguish and quantify.

First of all, HEs are not proportional to the engine outputs, in MAN engines. For cost saving reasons, they used for ages the same shell for the heat exchangers of V8, V10 and V12 engines, slightly adapting only the internal tube bundles.
This means that the same shell size is used for a power range that goes from the V8/680hp all the way up to exactly double of the most powerful V12.
Actually, the V12 is stretched even further in their current range (up to 2000hp), but since they went north of 1360hp on the V12 and 900hp on the V8, the engine was heavily redesigned, including a completely different HE.
Which btw is more similar to those already used by MTU and Cat since years, whether Portofino likes that or not...
Anyhow, as a consequence of the common shell, in the smaller power V8s the HEs are pretty oversized, and the cooling liquid temperature typically remains constant in anything but VERY dirty HEs, when even with the thermostatic valve constantly open, the cooling capacity is not enough anymore.
In other words, when you begin seeing a cooling liquid temp increase in the V8, it means that the HE cleaning is well overdue, while the V12 are more sensitive to a lower amount of clogging.
I am not sure about the HE shell of the inline 6 engine, but I'd be surprised if it were redesigned and enlarged proportionally to the higher power that was squeezed out from it over time. SInce they didn't for the V8/10/12, it would be weird to do that for the inline 6, whose output increases were nowhere near comparable to the differences between the V engines.

But wait, there's more.
Another major factor is the engine load, which heavily affects the heat produced by the engine.
This means that the same boat, with the same engines and the same heat exchanger conditions - let's say a bit dirty, but not heavily clogged - might well be still within the HE capacity and show no signs of temp increase when running very light, but start overheating a bit after filling her with fuel and water - or when running with some hull/props growth.

Last but not least, sea water temperature.
Partially clogged HEs can still do their job perfectly with coldish sea water, say in April.
Then you don't use the boat for a while, and when you go out again in June, with a 10 degrees warmer sea water, they are not man enough for the job anymore.

Another thing worth mentioning when talking of MAN HEs, even if not directly connected to engine temps and risk of overheating, is the fact that some sharp Bavarian engineer, decades ago, must have though that it was a good idea to use aluminum for the HE shells, while all other components (tube bundles and their covers) are properly built, i.e. in bronze.
Add to that the other clever idea of not fitting any engine anodes, and it doesn't take a metallurgy scientist to envisage the risks of this design flaw.
But this is for a future thread on this specific topic.
In the meantime, if anyone would be curious to see how just cleaned tube bundles look like, here's a couple of pics...

 

[Sticky Fingers]

Well this has turned out to be an excellent thread, thanks to everyone for their contributions. I've learned a lot.

 

[MapisM]

Secondly, it is not always needed to dissasamble the cooler to clean it physically. It is also possible to clean it chemically by flushing it without disassabling. This saves you the costs of the gaskets, which are actually quite expensive at MAN, plus a lot of man-hours Of course once in a while, the gaskets should be changed as well.

I meant to mention this in the previous post, but I forgot.
In principle, I agree that most of the clogging happens on the raw water side of the HE, for obvious reasons. And that side can indeed be flushed without pulling out (and afterwards back in, which are in itself rather tricky jobs, not to be underestimated) the tube bundle.

Otoh, over time, some deposits of God knows what do stick also on the fresh water side, which can only be cleaned properly after the tube bundle removal.
Just to give an idea, below is how the very same thing of the previous pic looked like before cleaning.
Not too bad, one might think at first sight.
But the part circled in red shows that what can be seen everywhere is not the tubes metal, but rather a layer of deposit.

Of course, if and how much that affects the actual cooling capacity of the thing, that's anyone's guess.
But seeing it completely removed gives some additional peace of mind anyhow. :encouragement:

 

[Eren]

Actually, in my experience it's much more tricky to estimate the heat exchangers conditions based on the cooling liquid temperature alone.
There are in fact several other factors, that can be more or less relevant, but whose effect is hard to distinguish and quantify.

First of all, HEs are not proportional to the engine outputs, in MAN engines. For cost saving reasons, they used for ages the same shell for the heat exchangers of V8, V10 and V12 engines, slightly adapting only the internal tube bundles.
This means that the same shell size is used for a power range that goes from the V8/680hp all the way up to exactly double of the most powerful V12.
Actually, the V12 is stretched even further in their current range (up to 2000hp), but since they went north of 1360hp on the V12 and 900hp on the V8, the engine was heavily redesigned, including a completely different HE.
Which btw is more similar to those already used by MTU and Cat since years, whether Portofino likes that or not...
Anyhow, as a consequence of the common shell, in the smaller power V8s the HEs are pretty oversized, and the cooling liquid temperature typically remains constant in anything but VERY dirty HEs, when even with the thermostatic valve constantly open, the cooling capacity is not enough anymore.
In other words, when you begin seeing a cooling liquid temp increase in the V8, it means that the HE cleaning is well overdue, while the V12 are more sensitive to a lower amount of clogging.
I am not sure about the HE shell of the inline 6 engine, but I'd be surprised if it were redesigned and enlarged proportionally to the higher power that was squeezed out from it over time. SInce they didn't for the V8/10/12, it would be weird to do that for the inline 6, whose output increases were nowhere near comparable to the differences between the V engines.

But wait, there's more.
Another major factor is the engine load, which heavily affects the heat produced by the engine.
This means that the same boat, with the same engines and the same heat exchanger conditions - let's say a bit dirty, but not heavily clogged - might well be still within the HE capacity and show no signs of temp increase when running very light, but start overheating a bit after filling her with fuel and water - or when running with some hull/props growth.

Last but not least, sea water temperature.
Partially clogged HEs can still do their job perfectly with coldish sea water, say in April.
Then you don't use the boat for a while, and when you go out again in June, with a 10 degrees warmer sea water, they are not man enough for the job anymore.

Another thing worth mentioning when talking of MAN HEs, even if not directly connected to engine temps and risk of overheating, is the fact that some sharp Bavarian engineer, decades ago, must have though that it was a good idea to use aluminum for the HE shells, while all other components (tube bundles and their covers) are properly built, i.e. in bronze.
Add to that the other clever idea of not fitting any engine anodes, and it doesn't take a metallurgy scientist to envisage the risks of this design flaw.
But this is for a future thread on this specific topic.
In the meantime, if anyone would be curious to see how just cleaned tube bundles look like, here's a couple of pics...

I simply take my hat off to such depth of knowlegde. However in all of the cases listed above, the HEs still give signs of getting clogged much in advance, giving the captain/owner lots of time to react.

I have recently started a thread about when to change my air filters. MAN have equipped my boat's engines with tons of sensors together with a diagnostic screen which report me about 40 different data about the engines. One of this data is directly about the status of the air filters. It is “air pressure after filter” data, or also known as “depression” at engine terminolgy. The more clogged your air filter, the bigger minus pressure you see at your screens. Furthermore, to help you with your evaluation, there are green-yellow and red lights next to this data box. Green says “all is OK”, yellow says “well it is time to change your filters now”, red says “you definitely should have changed them yesterday”. The MAN service schedule tells me to change them every year. Filters costs EUR 500 x 2. By the way, nobody, nobody including MAN service guys tell me “Well, mmm, actually our engineers had designed a very useful sensor here, which you yourself can check on the screen and decide on scientific data if a change is needed or not”. All of these information I have to dig and find myself. If I change my filters every year, everybody, MAN, service guys, etc are all happy, excluding my vallet. So what do you think, should I trust blindfoldedly to the service schedule or to scientific data that I can read and evaluate?

Well, it is actually difficult to defend my position. On one side, there is MAN, on the other side it is Eren. Definitely not a fair match. I understand and accept that MAN should write the service schedule that way but at least personally, I know that it is possible to evaluate the schedules and still have very healthy engines.

 

[MapisM]

Well, it is actually difficult to defend my position. On one side, there is MAN, on the other side it is Eren. Definitely not a fair match. I understand and accept that MAN should write the service schedule that way but at least personally, I know that it is possible to evaluate the schedules and still have very healthy engines.

Eren, correct me if I'm wrong, but it seems to me that you perceived my previous post as meant to dismiss your pragmatic view and support instead the theoretical one that you can find on maintenance schedule booklets.
If so, well, you are barking up the wrong tree, because my approach is exactly the same as yours! :encouragement:
By throwing in some additional things to consider, I just wanted to contribute with additional factors, which I already experienced first hand even if I've only had MAN engines for a couple of years.

By the way, with my mechanical engines, most stuff is actually even more complicated to monitor - the cooling liquid temp being a typical case: there's a big difference between digital displays with a one degree granularity and small analogue gauges, even if the bulb sensor isn't necessarily less accurate.
In fact, whenever I want to make a proper check of all sort of temperatures (not just cooling liquid), I go inside the e/r with my IR gun.
Possibly my most valuable tool, which also allows one measurement which is not included in any electronic engine display, i.e. the EGT at single cylinder level.
Just by approximation obviously, since no IR gun can pass through solid metal.
But if one defective (i.e. leaking, typically) injector creates a higher EGT in one cylinder, such increase could be hardly noticeable in the MMDS display, which only measures the whole cylinder bank (i.e. the average of 6, on an inline 6 or a V12).
Otoh, once you know where to point the IR gun on individual cylinder headpipes, I have it on very good authority that any dangerously high EGT temp is reflected in a significantly higher (compared to the other cylinders) headpipe temp.

But I digress. In the case of the filter, I'd love to have a depression indicator, but there's none on mech engines.
So, in this case, I go by Mk1 eyeball, and on that basis the 2+2 filters which I replaced last season are going to enjoy another year of service, even if last year I clocked much more hours than my usual average, because of the delivery trip around 3/4 of the IT peninsula.

Therefore, no disagreement at all on the principle that the official maintenance schedule can be taken with a pinch of salt, without any negative effects on the engines health - and some positive ones on the wallet!

Talking of which, this statement raised my eyebrows:

Filters costs EUR 500 x 2

In fact, the filters of my V8/800 (worth 75 Eur or so) are shared with a lot of other MAN engines.
Again, not sure about inline 6, but they are exactly the same from the old mechanical V8/680, all the way up to the common rail V12/1360.
Now, IIRC you've got the 1550, right?
If so, afaik that's a widely redesigned version of the previous V12, not only with different HEs, but also longer stroke, among other changes.
So, considering the price difference, I assume you aren't just being ripped off by a bandit MAN dealer, but they changed the filters design completely.
I'm just wondering what on earth can justify a 500 Eur price for a component whose equivalent on a 1360hp engine costs a whopping 85% less!
Are you sure they aren't the metallic (hence washable) version, rather than the normal paper ones?
Someone told me that a metallic washable type is also available for older engines like mine, but considering the relatively reasonable cost of the paper ones I never investigated this option further...

 

[pan]

Last service done this year, air filters were 119e + iva each, for R800 (in line 6) FYI :encouragement:

 

[Portofino]

I, am in agreement with ERINs approach .Theres a huge overkill with the 2 year regular crack open of the coolers regime.
I just watch by diagnostics carefully.
Tbo my temps have not altered in 5 seasons , or anything else for that matter .
What i do note is the creep of load and EGT ,s as the season ( summer only ) progresses,but that only tells me it’s time to snorkel or dive to clean the props which is easy enough anyhow .
I get PAN , s point about residuals and ERIN ,s about over diligent buyers / surveys etc .
There’s at the mo is not one Itama 42/48 on the market and since ownership I have two separate requests to sell it .But I get if there’s 12 or more in the Med for sale at any one time the service history comes next after price .
Currently I note 17 Portofino 47 / 48 ,s -buyers market for comparison.
So rightly or wrongly extended “crack open intervals “ for me personally is not gonna really effect residuals .

My reassurance re putting back a “crack open “ is 3 years ago I saw inside one and the MAN engineer said they were ok and even he rolled his eyes when I mentioned the 2 year interval .

What I do notice after a long winter lay up they loose 1 or 2 degrees after an hour’s blast at 1900 rpm say drop from 86 to 84 , the 84 will be my season temp - possibly rise back to 85 mid August.
They drop to 80/81 at tick over .This may be MapisM,s point of a common cooler part shared , but bear in mind the V12 ,s may be twice the power but they have TWO coolers one each side as the I6 is one bank .They feel oversized or the water pump oversized, who knows the end user me feels little inclination to crack them open .


I have just finished servicing them and did the tappets which are a 400 hr interval .Wow what a difference they purr like a pussy cat and feel even more powerful.
With the I6 we found 5 exhaust valves and 2 inlet needed adjustment on the port engine and with the STB 3 exhaust and 1 inlet .You only need one for the tapperty noise .
The valve overlap thingy is the most crucial part of achieving stated power output in highly tuned engines it’s not to be underestimated.

Oil and filters regardless of hrs or any man maths of attempting to cross reference with lorries / busses are imho the most important aspect that need changing every year .We are averaging about 80 hrs .The additive package deteriorated occurs with time not hrs nor “ mileage “ .
The belt needs it’s tension checked and adjusted , not replaced unless signs of cracking / fraying ,the air filters I can see the charge air inlet pressure so again no need to change every year .Obviously the fuel filters .
Even the impellers I do not do every year as the inlet pressure and cooler temps and oil temps are all within range .
This year oil was €300 for 65 L , fuel and oil filters another €100 so that’s it €400 all in this year .
We do the gearbox oil every alternative year peanuts €20 in oil .
As said earlier I stumbled across a shop flogging air filters for €60 so I snapped a couple up before someone realised they had been mislabelled the price .Normally I pay about €90 each .Fitted last Oct .
Advantage of DIY is that you know the correct MAN spec ( 3275 for me ) oil is put in .




1900 rpm burns approx 200 L / hr and runs at 30 knots .

Dropping to 27 knots drops the fuel burn 160 ish ?

Compared to my previous Volvo Penta KAD 300 with outdrives these MAN s with 3 x the displacement cost a fraction in maintenance .
I was paying €5000 every 5 years for a cooler cleaning turbo refurb , turbos did not last long , water pumps leaked , elbows rotted , risers rotted all that’s on the inside .
Fortunately the drives lasted but they were removed every two years for the bellows and stripped down re sealed iirc €2000 .
Hardly any of the above long range diy er able .

As far as fuel burn being double or more , it’s not really like for like and basically I don’t care as the fuel bill is a known controllable variable as opposed to running VP aged outdrives which a unknown un controllable variables re service and repairs .

 

[Eren]

Eren, correct me if I'm wrong, but it seems to me that you perceived my previous post as meant to dismiss your pragmatic view and support instead the theoretical one that you can find on maintenance schedule booklets.
If so, well, you are barking up the wrong tree, because my approach is exactly the same as yours! :encouragement:
By throwing in some additional things to consider, I just wanted to contribute with additional factors, which I already experienced first hand even if I've only had MAN engines for a couple of years.

MapisM, I already understand that you are at the same view with me. "Eren against MAN" example was given in general.

By the way, yesss, the filters for my engines really costs EUR 500 each from MAN. They are really very big and I think they are overpriced due to low production quantities. However, I found them from the OEM filter producer MANN (yes MANN, not MAN) at the price of EUR 250 each and ordered them. I will replace them when the diagnostic screens show the yellow light for that.

A valuable info for MAN engine owners, all filters for MAN engines are usually produced by MANN. If you can get the original part numbers of your filters, you can crosscheck from the below web site and get them at usually half price from their nearest dealer.

https://catalog.mann-filter.com/EU/eng/oenumbers

If not found at MANN, Fleetguard/Cummins or Donaldson cross check sites can be checked as well, who are also major and high quality filter producers. I know that for smaller engines the marginal gain may not be that big but, it won't hurt if 100-200 EURs will stay in your pocket at every service. This applies not only for MAN engines but for all others as well. Please note that this is not like using cheap far east copies of the filters. These are the producers who produce for the engine manufacturers. So the only difference will be that it won't write "MAN", "CAT", etc on the packing.

I am sure this is known by most of the forumites here but still can be a useful information for the ones who are new to boating.

 

[MapisM]

A valuable info for MAN engine owners, all filters for MAN engines are usually produced by MANN. If you can get the original part numbers of your filters, you can crosscheck from the below web site and get them at usually half price from their nearest dealer.

https://catalog.mann-filter.com/EU/eng/oenumbers

Thanks Eren,
but it seems that the filters for all V8/10/12 engines from 680 to 1360hp are not available from MANN.
This is the part# search, just in case anyone else is interested.
Not that I'm really worried, anyway - their cost ain't as silly as for your filters, also when supplied by MAN.

Btw, I suppose you are right ref. lower volumes for your filters, particularly considering that the "older" ones are widely used also in trucks.
Though I suspect that there is also a rip-off component, i.e. pricing made considering the type of gin palaces normally powered by 3000+ ponies...

 

[DAW]

I strongly agree with Porto's comments about oil and oil filters. I'm currently looking at a boat where there is a good history of oil samples on MAN V8 engines that have not been serviced regularly due to very low annual hours. You can clearly see the concentration of elements from the anti-wear and anti-corrosion additives deplete over time ... we discussed this with the local service agent who went back to the oil manufacturer. We were told the additives drop out of suspension and after two years are usually more or less gone (i.e. they exist as sediment in the sump or the filters) regardless of how many hours the engines have done. It doesn't mean the oil is useless, just that its anti-wear and anti-corrosion properties are dramatically reduced (which is more of a problem if the engines are not run regularly or over the winter months).

We use a lot of trucks and heavy equipment in the business I work in and oil analysis is a routine part of everyday life for the engineers. They replace oil based on chemical analysis not maintenance schedules. In some applications wear rates and metal content is the issue,. In others, wear is minimal and it is loss of additives and performance over time. My guess is that for most boats doing only 50-100 hours per year, time is the enemy and not wear.

FWIW, all the MAN agents I have used in the past are of the view that provided operating temperatures are within tolerances, once an engine is out of warranty its OK to flush the heat exchangers with cleaning solution every two years and only disassemble for more thorough cleaning and replacement of seals every four.

 

[MapisM]

This may be MapisM,s point of a common cooler part shared , but bear in mind the V12 ,s may be twice the power but they have TWO coolers one each side as the I6 is one bank

Wrong apples and oranges comparison PF, on two counts:

1) My comparison about the shared HE shell was between V engines, i.e. from V8/680 to V12/1360.
When I mentioned inline 6 engines, it was just to say that I'm not sure of their HEs modifications over time, if any.
But the HEs of V and inline engines are different anyway - a quick glance is enough to tell that.

2) V engines do NOT have separate HEs for each bank: there's just one, placed in the same position as in inline engines.
Btw, this architecture was maintained also for the newer V engines, whose Cat/MTU-like HEs are completely different.
What was changed over time in the cooling of V engines are the aftercoolers - one initially, and two afterwards.
I'm not positive about when they introduced the two aftercoolers setup, but IIRC that's what Deleted User has on his V12/1224.

 

[MapisM]

I'm currently looking at a boat where there is a good history of oil samples on MAN V8 engines...

All well and good Daw, but so what? I mean, I know the theory, and I'm not arguing with it.
But in 2017 I bought a MAN V8 powered boat whose engine oil was never sampled. 2003 engines, 1400+ hours clocked.
I did NOT take oil samples, and never will.
Doesn't that make life easier?

My personal take on this is that on average pleasure boats the hell will freeze over well before engines wear will be a problem.
Of course, this might not be true whenever maintenance has been badly neglected.
But I also think it's very unlikely that in these cases the poor engine conditions aren't reflected also in other sub-optimal running parameters.
Anyway, I appreciate that this is an each to their own matter, to some extent.