What would you check, change or refurbish on 11 year old, 1,250 hours D-12's?

[Deleted User YDKXO]

100% agreed, I also wouldn't bother.
M, the AZ46 must have had some weird connection, in your boots I'd check the F630 arrangement first.
My bet is that there's a much easier/quicker way to keep her going with a dead alternator without replacing it - which btw is also something you don't want to do in open, possibly rough sea, and in a hot e/r.
Glad to have a look at your electrical scheme together, if you wish.
Incidentally, coming to think of it, I wanted to ask you a favour and check if you have in your manuals anything related to those red current displays (Amperes and Volts) located on the electrical panel.
In fact, they are very similar to the ones I have on my boat, one of which just went blank, and I have no documentation at all about them.

Yes sure P. As you know we will be in CF tomorrow night. Come over for a beer and we can go over the electrical circuits. I would value your opinion on whether an alternator failure would cause the same kind of problem I had on the AZ

 

[Deleted User YDKXO]

LS1 thanks for that interesting and informative post

 

[Nick_H]

LS1 thanks for that interesting and informative post

Yep, thanks Latestarter and Bandit for useful info.

I do plan to get a VP trained engineer to do a full inspection of the engines, gearboxes and drivetrain, but I find it very useful to have some thoughts from the experts on here first, so I can at least check the engineer has considered everything.

I'll suggest a cylinder contribution test prior to any decision on removing or changing injectors. I'm already planning to refurb the water injection elbows although the body of the units seem to be in good shape, and both intermediate elbows have been or will be replaced with new. The stern seals are Tides Marine, but I'll check if there are spare seals already on the shaft. I don't remember seeing them, but maybe I've just missed them. I'll also check water flow to them. I have drain cocks on the fuel tanks, so will see what the fuel looks like when I drain some off then decide whether to have the fuel polished. I think the fuel in SoF is generally good quality, there's never any crud or water in the pre-filter bowls, or much muck on the filters when they're changed.

Bandit, what do you mean by "lapp the prop"? Also, with the extra weight of the gyro, tender and normal cruising gear, combined with warm air temps and some drag from the antifoul, I'm about 100 rpm down at WOT. Is this enough to justify having the props altered, or is it close enough? Edit: I've always been a bit down on max RPM, it's not a recent thing.

 

[Latestarter1]

If you are 100 rpm down on rated at WOT request % engine load off Vodia

 

[Nick_H]

If you are 100 rpm down on rated at WOT request % engine load off Vodia

Will do, thanks

 

[jfm]

Latestarter, many thanks for that interesting history

Nick, each to their own, but fuel polishing is pointless imho. Your engines return perhaps 90% of the fuel they draw, so every time you use the boat you polish the fuel thru both primary and secondary filters.. Why do it again therefore? Cleaning out a pile of crud at bottom of tank is worthwhile I suppose

Lapping the prop is putting grinding paste on the taper and spinning the prop by hand, to clean up the taper and get a better fit

Personally I would be pleased to be 100rpm down. Engine manufacturers only sign off on a new boat if it hits rated rpm at WOT. But if you always cruise at say 70% of max rpm, or less, you actually want more pitch than the pitch that gives you rated rpm at WOT, so as to extract the power the engine is capable of delivering at 70% of max rpm

I'm a bit unclear about how the engine's ecu knows cylinder contribution. What parameters are measured?

 

[Bandit]

Lapping as described above to get a very good fit if prop to shaft, generally not undertaken by boat builder and often the prop sits on high spots or can hammer the key damaging shaft, key and prop.

Water & crud does build up in tanks over time with condensation, poor filler caps of arrival with new fuel. Treatment and polishing is a preventative measure.

Also give the steering system and rudder shafts a good inspection inside and out.

 

[MapisM]

Yes sure P. As you know we will be in CF tomorrow night. Come over for a beer and we can go over the electrical circuits. I would value your opinion on whether an alternator failure would cause the same kind of problem I had on the AZ

With pleasure.
I would think that it should be sufficient to disconnect the alternator, and see if the battery charger works as it should.
Swapping cables, as jfm did, is a sort of less temporary workaround, but once you see that the batteries of either engine running with a dead alternator are not discharging (courtesy of the battery charger), you know that you have a way to get home with both engines running, with no need to replace the alternator.

Glad to hear other ideas, if anyone think that I'm missing something.
I'd rather not be sued by Deleted User insurance, after they'll have to refund him a total loss of an exploded boat!

 

[MapisM]

I'm a bit unclear about how the engine's ecu knows cylinder contribution. What parameters are measured?

+1.
I also don 't get that, from the otherwise VERY interesting post from LS.
Btw, I never heard of any real time measurement of combustion quality based on the exhaust analysis (let alone at cylinder level!), as you suggested in your previous post, which I agree would be the only proper way to measure ex-post what each injector is actually doing, imho.
Maybe there's some sort of control on how much fuel the injector is actually sipping, compared to how much it should, based on the ECU instructions?
Just a thought - curious to hear from LS about that.

if you always cruise at say 70% of max rpm, or less, you actually want more pitch than the pitch that gives you rated rpm at WOT, so as to extract the power the engine is capable of delivering at 70% of max rpm

I see what you mean, and don't disagree on the principle, but out of a rated 2300rpm, I believe that 100rpm less is a difference that might be worth shortening the pitch a bit.
I've seen several sea trial sheets of boats with C9/12/15/18 (sorry, I have no 32s to compare), and in all of them the load at 70%rpm is always WAY below 100%. I'd say around 50% on average, but even less in some cases.
There must be a reason for propping boats in such way that you are always very far from using the full power that the engine can deliver (i.e. run it at 100% load), at anything below WOT/rated RPM.
Actually, coming to think of it, Cat proudly mentions the possibility to use some of their engines at full load also below the max rated RPM (that's what they call "wide operating speed range", aka WOSR, which might apply also to Match engines), but I'm not aware of other builders suggesting the same.
And even with Cat, that range surely doesn't stretch to 70/100%. More like 90/100%, IIRC.

 

[jrudge]

The CAT % load is a bit of a mystery to me.

The C18s I have are life based on a 30% average load. I don't poodle, I get out of the marina and go somewhere. I tend to use high power settings as, sea state permitting, I get there faster and on my boat per the clever fuel monitoring use less diesel per NM.

Now ... the boat is a year old. It has 240 hours on it and an average load of 38%,

The only way to bring it down would be to leave it idling in the marina which would be a totally pointless exercise.

I can see on a car / truck 30% would be a fair average load, but not on a boat where high power is just a fact of life!

 

[Latestarter1]

+1.
I also don 't get that, from the otherwise VERY interesting post from LS.
Btw, I never heard of any real time measurement of combustion quality based on the exhaust analysis (let alone at cylinder level!), as you suggested in your previous post, which I agree would be the only proper way to measure ex-post what each injector is actually doing, imho.
Maybe there's some sort of control on how much fuel the injector is actually sipping, compared to how much it should, based on the ECU instructions?
Just a thought - curious to hear from LS about that.


I see what you mean, and don't disagree on the principle, but out of a rated 2300rpm, I believe that 100rpm less is a difference that might be worth shortening the pitch a bit.
I've seen several sea trial sheets of boats with C9/12/15/18 (sorry, I have no 32s to compare), and in all of them the load at 70%rpm is always WAY below 100%. I'd say around 50% on average, but even less in some cases.
There must be a reason for propping boats in such way that you are always very far from using the full power that the engine can deliver (i.e. run it at 100% load), at anything below WOT/rated RPM.
Actually, coming to think of it, Cat proudly mentions the possibility to use some of their engines at full load also below the max rated RPM (that's what they call "wide operating speed range", aka WOSR, which might apply also to Match engines), but I'm not aware of other builders suggesting the same.
And even with Cat, that range surely doesn't stretch to 70/100%. More like 90/100%, IIRC.

I only know Detroit Diesel strategy with DEDEC, engine knows at any speed/load how much fuel is required from lookup table to hold that specific load/engine speed and ECM adjusts fueling accordingly, however once engine senses an abnormal condition it momentarily performs a subroutine dropping out one injector at a time and measuring the rpm drop giving individual cylinder contribution. The clever bit is performing the subroutine in an unobtrusive manner and then making individual cylinder adjustments.

Understanding hidden subroutines in engine management systems is an art form, for example DD Series 60 KNEW when it was on a dyno and not installed in a truck and was programmed to spot the old EPA 13 mode test cycle which put engine on the honest emissions compliant retarded timing strategy. EPA was so horrified by chicanery involved to circumvent legislation fine was punitive, eventually resulting in Penskie having to sell out to Mercedes Benz.

As to CAT engine loading at installation sign off my understanding is that they would never allow 90% load on trials.

 

[MapisM]

I don't poodle, I get out of the marina and go somewhere. I tend to use high power settings as, sea state permitting, I get there faster and on my boat per the clever fuel monitoring use less diesel per NM.

Now ... the boat is a year old. It has 240 hours on it and an average load of 38%

Well, based on your usage style, I actually think that 38% makes perfect sense, compared to the 30% estimated by Cat as an average of all averages.
If you throw some pootling into the equation, which is something many P boaters do nowadays, THAT is something bound to lower the average significantly.
Much more than any difference in idling/maneuvering, which is rather affected by the number of short vs. long trips: if you mostly do the first, idling is bound to be proportionally higher than with the latter.

 

[MapisM]

once engine senses an abnormal condition it momentarily performs a subroutine dropping out one injector at a time and measuring the rpm drop giving individual cylinder contribution. The clever bit is performing the subroutine in an unobtrusive manner and then making individual cylinder adjustments.

Aha! That makes perfect sense, very clever indeed.
Logging off now, must clean the coffee I spilled on the cockpit while reading the chicanery story, before swmbo starts screaming...

 

[Nick_H]

Logging off now, must clean the coffee I spilled on the cockpit while reading the chicanery story, before swmbo starts screaming...

Going way off topic now, but I once ended up with a company making emergency breakdown warning triangles for a major German car manufacturer. Amongst many other criteria, warning triangles must pass a wind deflection test. The management told me that the triangles we were making originally failed the test, so they asked the toolroom to make a false protractor, with the degrees slightly skewed. Two weeks later the test company returned and were given the exact same warning triangles to test, which obviously then passed.

 

[jfm]

Aha! That makes perfect sense, very clever indeed.
Logging off now, must clean the coffee I spilled on the cockpit while reading the chicanery story, before swmbo starts screaming...

+1. Many thanks for that explanation LS - makes perfect sense
Yep, afaik Cat UK wont sign off a marine engine installation unless it hits minimum rated rpm at WOT/100% load. With my boat they accepted JUST hitting the minimum, because I wanted that for the reasons given above

 

[MapisM]

Going way off topic now...

Since you as the OP don't mind a bit of o/t, I guess I can throw in another example, having now cleaned (nicely btw, just in case anyone wondered about how bad coffee can be on teak) the mess...
If you thought that a warning triangle, as a safety equipment, is worse than cheating on emissions (which "only" affect the planet after all ), well, think again: guess which is the most popular method used by pharmaceutical industries (and before someone mention, I'm NOT talking just of Italian ones) to get the approval of their drugs?
Hint: think of sh!t for its colour, and of what you used for sending letters before the email took over...

 

[MapisM]

Despite the success of the Series 60 GM suddenly sold Detroit Diesel to Roger Penskie.

LS, in hindsight, considering your post that followed, deciding to sell a successful business wasn't such a stupid move, after all!
They must have known their stuff better than anyone else, surely...

 

[Deleted User YDKXO]

Now ... the boat is a year old. It has 240 hours on it and an average load of 38%,
The only way to bring it down would be to leave it idling in the marina which would be a totally pointless exercise.

Or could try trolling for a few hours to see if you could catch a tuna or something! Look on the bright side. Your pedal to the metal boating style puts less hours on the engines so your boat will be worth more when you sell it

 

[spannerman]

As far as I'm aware as I have never heard of it either in the workshop or on VP diesel injection courses, the D12 has no system for compensating for underperforming injectors. There is only one way to find out what the individual cylinders power contribution is, and that is to run the cylinder balance programme in the Vodia, which interrupts the injection signal from the ECU with recovery time before dropping the next one out. I can't see how it would work in practice as an underperforming cylinder could also be caused by mechanical problems, i,e, rings, valves, so pumping in extra diesel to pull the revs up won't help.
And there is absolutely no exhaust gas analysis on these engines so no feed back loop to the ECU as on petrol engines, the only sensor would be overall exhaust gas temp.
Hopefully Volvopaul will confirm this unless he knows something I don't.

 

[jrudge]

And in the news today vw have been caught doing the same thing. Car detects it is under test and changes the emissions profile. Clever ... Until you get caught !

I only know Detroit Diesel strategy with DEDEC, engine knows at any speed/load how much fuel is required from lookup table to hold that specific load/engine speed and ECM adjusts fueling accordingly, however once engine senses an abnormal condition it momentarily performs a subroutine dropping out one injector at a time and measuring the rpm drop giving individual cylinder contribution. The clever bit is performing the subroutine in an unobtrusive manner and then making individual cylinder adjustments.

Understanding hidden subroutines in engine management systems is an art form, for example DD Series 60 KNEW when it was on a dyno and not installed in a truck and was programmed to spot the old EPA 13 mode test cycle which put engine on the honest emissions compliant retarded timing strategy. EPA was so horrified by chicanery involved to circumvent legislation fine was punitive, eventually resulting in Penskie having to sell out to Mercedes Benz.

As to CAT engine loading at installation sign off my understanding is that they would never allow 90% load on trials.