Ideal Generator?

[pdf27]

Originally Posted by Dockhead

Sounds very intriguing, and I think someone suggested that in this thread above. I would love to see something like this developed.

But certainly out of the question for a vessel such as the one I'm working on specifying. For this particular vessel, which is supposed to be extremely reliable and field serviceable, the design can't have anything exotic in it. Imagine trying to get a turbine mechanic in Greenland, or jet fuel in one of the fishing ports up there, and imagine how much one-off engineering such a system would take.

I need something extremely simple and conservative. The inherent reliability of reciprocating engines is not one of the design problems.

It has been developed, and a marinised version of the Capstone units is on sale (see C30 AC | Microturbine Marine Energy) - problem is once they're built into units you lose most of the weight advantages over a diesel unit, and they're also likely to be ferociously expensive. The smallest unit Capstone do is rated at 29kW of electricity, and the efficiency drops off significantly if they're run at less than full power. It should also be noted that it drinks 11 litres/hour at said full power, and weighs half a tonne.

One thing I am hopeful of is truck/lorry APUs: at the moment most heavy vehicles use an alternator attached to the engine for power (cab heating, refrigeration, etc.) and this is increasingly being banned. Right now most available APUs are little 1-2 cylinder diesel engines, but there is an awful lot of work going into fuel cell variants which can run off diesel fuel. Those should have most of the attributes you want in a marine generator - cheap (looking at production levels of ~100,000 per year), silent, low vibration, relatively small in both output and size (if you've got batteries and an inverter anyway, how many kW do you really need?) and in theory pretty robust since they will have far fewer moving parts than an engine. Won't be available in time for you, realistically (they're talking about shipping the first production units in about 18 months from now), but a few years after that I think they'll start becoming very common.

[mcarling]

There is no reason to run the gas turbine at less than full power in the scenario described. Much of the weight you quote is for the enclosure, insulation, heat exchanger for hot water, etc. I can't find now the pdf with the spec for a bare 30KW Capstone with a DC generator but it was well under 200kg. The 12KW Bladonjets gas turbine is 220kg including the generator, enclosure, insulation, fuel tank, etc.

[Dockhead]

Originally Posted by pdf27

It has been developed, and a marinised version of the Capstone units is on sale (see C30 AC | Microturbine Marine Energy) - problem is once they're built into units you lose most of the weight advantages over a diesel unit, and they're also likely to be ferociously expensive. The smallest unit Capstone do is rated at 29kW of electricity, and the efficiency drops off significantly if they're run at less than full power. It should also be noted that it drinks 11 litres/hour at said full power, and weighs half a tonne.

One thing I am hopeful of is truck/lorry APUs: at the moment most heavy vehicles use an alternator attached to the engine for power (cab heating, refrigeration, etc.) and this is increasingly being banned. Right now most available APUs are little 1-2 cylinder diesel engines, but there is an awful lot of work going into fuel cell variants which can run off diesel fuel. Those should have most of the attributes you want in a marine generator - cheap (looking at production levels of ~100,000 per year), silent, low vibration, relatively small in both output and size (if you've got batteries and an inverter anyway, how many kW do you really need?) and in theory pretty robust since they will have far fewer moving parts than an engine. Won't be available in time for you, realistically (they're talking about shipping the first production units in about 18 months from now), but a few years after that I think they'll start becoming very common.

Well, in theory that doesn't sound too bad. The partial load inefficiency would be terrible with direct drive and lead acid batteries, but with LiFePo batteries and electric propulsion, you could use full output of the turbine and then shut it down. With air bearings probably doesn't need to be warmed up and probably doesn't mind start-stop operation.


Fuel cells which can use diesel fuel are also really interesting. If they are silent, they could run continuously -- you only care about the average output meeting your average consumption. Could work like a kind of sunless, 24h solar installation.


I'm afraid all of this is coming too late to help me, though. No way am I taking a mission critical system in beta test condition, up to the Arctic. I am going to need to go low-tech, rather than high-tech.

[mcarling]

If I wanted extreme reliability in the high latitudes, I would go with electric propulsion and diverse methods of producing electricity. An electric motor is much less likely to fail than a reciprocating diesel and it's plausible to carry a spare.

[valhalla360]

Originally Posted by mcarling

If I wanted extreme reliability in the high latitudes, I would go with electric propulsion and diverse methods of producing electricity. An electric motor is much less likely to fail than a reciprocating diesel and it's plausible to carry a spare.

For house loads only, that works fine. Once you add in propulsion short of the exotic turbine generators, you haven't eliminated the reciprocating engine. Solar panels and wind generators aren't going to provide enough output to make any meaningful difference for propulsion.

The "reliability" of electric motors is red herring. Modern IC engines are extremely reliable.

If the OP is going to put in multiple large electrical sources regardless...I still say it makes more sense to just put in dedicated generators with one sized for house loads and a larger sized so when paired with the house generator, it produces the required peak propulsion HP. This allows you to maximize efficiency by pairing the generator to the load in question and the small generator can function as a get home power source in an emergency.

[Dockhead]

Originally Posted by mcarling

If I wanted extreme reliability in the high latitudes, I would go with electric propulsion and diverse methods of producing electricity. An electric motor is much less likely to fail than a reciprocating diesel and it's plausible to carry a spare.

In theory, maybe that's right. What you write actually follows the systems architecture principle which is at the heart of what I'm doing here -- use the same source of power for as many different systems as possible, the make that source of power as robust and redundantly supplied as possible. So logically, make the whole boat totally electric including propulsion and then have many robust sources of electrical power. It makes sense.


But in practice, marine diesel engines are extremely reliable and extremely serviceable after 100-odd years of development.

And electric propulsion -- although it has existed for as long as diesel propulsion has -- is not well developed in this size class, and what is available is pretty experimental.

[estarzinger]

Just a couple random observations:

1. It makes a big difference if you want a >10kw 'generator' or a <5kw one. At +10kw a standard commercial big brand generator is the only option that makes sense (to me). They are well proven, with a huge experience base and engineering behind them (diesel generators must be one of the most prevalent and perfected artifacts of 'modern civilization' next to the assault rifle). But under 5kw there is not such a commercial market or base and the commercial offerings are less good and the 'school bus' approach makes more sense. I don't think that DockH has detailed his proposed electrical requirement, which would include at least (a) desired max gen run time/day and (b) maximum Kw's needed during that run time, so we don't know where he falls on this spectrum.

2. If you are building a 'mostly electric, mostly charged by diesel' solution, then to get maximum system reliability, probably the highest leverage placed to focus your attention is in fact not on the actual generator design (which are pretty damn good), but rather (a) on maintenance access to the gear and (b) the fuel system (the most likely single point of failure in a multi engine diesel approach).

Excellent maintenance access requires a significant space allocation. Dashew's own 80'er has spectacular maintenance access. That 64'er, while quite good compared to most 'yachts', is very cramped compared to Dashew own boat. An approach here which I have used in helping a couple owners is to start by building a detailed 3d CAD drawing of the equipment space (a couple times then going to an actual physical mockup) . . . without imposing any vessel size constraint on the space. Making sure that it is 'an engineer's dream' - as compact as possible while still allowing truly excellent access to everything (and you need to get into the detailed weeds of some of the gear to understand what parts might need access, like the stupid backwards water pumps on yanmars). And then, only then, use that space requirement to essentially determine the size of the vessel.

Regarding fuel systems . . . . there are a couple possible different philosophies. Personally I like the 'large isolated gravity day tank' solution, because it gives you protection from contaminated fuel and from pinhole fuel/air leaks and from pump failures. To execute it you just need to design a filtering system between the main tanks and the day tanks that is truly bulletproof - for instance will not let water pass even if it is overwhelmed by water in the main tanks, and will not let the day tank run dry without multiple operator errors.

3. Ultimately, always on diesel fuel cells seems like the ideal solution, but today the methanol EFOY fuel cells have a time between factory service of about 5000 hours, which is fine for the racers but only 200 days for a cruiser. So there would appear to be quite some development required before they are really ready.

But I might mention that there is another 'quiet always on' generator option that is available today - the sterling engine whispergen. If you plan to cruise in areas where you would need heating, and you do not need massive superyacht amounts of electricity, this is a decently attractive option. It has not had much marketing, and you would want to carry pretty comprehensive spares because otherwise you will have to get parts fedexed from NZ, but it is close to an ideal solution if you fit in their narrow niche.

4. Finally, I might comment that my personal sense of an important aspect of obtaining maximum reliability is focus on absolutely minimizing and simplifying your demand. I have written articles on that. But It's probably not worth discussing here because I have the strong impression that DockH wants to 'take everything with him' and is not interested in strongly simplifying. There's no right answer to this - Each to his own - but it does help reliability.

[sailnow2011]

Originally Posted by Dockhead

I'm still collecting ideas and thoughts for my next boat, if there ever is one, which will definitely be custom built. I started a thread about it last year which I can't find.

I was reading Noelex's classified ad for his old boat, and among many other excellent features, really liked his generator. It's a standard boat propulsion engine -- so already marinized with standard parts -- a huge plus for serviceability and parts availability -- driving a standard heavy duty alternator -- ditto. This is similar to some home-made DC generators we've seen on here, except that instead of a home-made marinization of an undersized Kubota, this just uses a standard propulsion engine from a much smaller boat.

For a long-distance high latitude adventure cruising boat, I think this is just the ticket -- the ultimate in robustness, serviceability, and simplicity.

I am not a fanboy of DC generators because I don't see any overwhelming advantage in efficiency. Now that we have modern charger/inverters which make a seamless conversion between DC and AC and back, I don't think we really care whether power comes to us in DC or AC form. I like heavy duty low speed AC generators and have had excellent service from my Kohler EFOZ6.5 and would not trade it for a homemade DC generator with a home-marinized Kubota, but something like Noelex's generator is something very different.

I think on my next boat I'll have something like that. I would use a Beta or Nanni, the smallest 3-cylinder propulsion engine they make. I would have a flywheel and jackshaft in place of the gearbox running two large frame Leece-Neville 36 volt or 48 volt alternators through short toothed belts. That will give a capacity of up to 6 or 7kW with both running, but by varying the engine speed and using one rather than both alternators, the output can be regulated.

I would have a third identical 36 or 48 volt alternator on the main engine. This gives great flexibility and redundancy in power generation, and one spares kit will cover all three alternators.

This power will charge a 36v or 48v battery bank, maybe LiFePo, which can absorb high charge rates, using this generator to its best advantage and allowing for short generator runs.

Having this kind of power on board eliminates the question of how to power the windlass, bow thruster, and furling gear.

The DC bank will produce AC power through ganged charger-inverters, maybe three like the Victron Multiplus I have now. This is not an ideally reliable unit, but in a gang of three the built-in redundancy will compensate. Like that there will be about 7.5kW of available AC power.

DC consumers powered through 24v or 12v droppers. Probably there will be one large 24v dropper powering a separate 24v bus.


To make the generator perfectly serviceable, I guess is should live above the main engine and under the cockpit sole. If this is bolted in place and easily removeable, or with a large opening hatch, then access should be ideal.

Everything needed to make the generator run, including its start battery, should be located right there in the same place and should be separated as much as possible from other systems.

Such a generator makes it easy to take off mechanical power for other purposes, but I think there's hardly any point to a mechanically driven watermaker pump or bilge pump, since you have nearly unlimited electrical power for this. Maybe a large mechanical bilge pump would make sense just for the case of some disaster which has knocked out power, but you can still start the generator since its start battery is separate and well above the waterline.

If you do a lithium bank then a DC generator is perfect because it will take every amp you can cram into it as fast as you can give it up. I would do, and plan to do on my first custom boat, a 1cyl kabota with 200 amp alternator for battery charging, and a correctly sized generator for the AC loads when needed such as AC/ washer dryer.
I have the kubota from nexgen/phasor now, and really like it.

[Dockhead]

Originally Posted by estarzinger

Just a couple random observations:

1. It makes a big difference if you want a >10kw 'generator' or a <5kw one. At +10kw a standard commercial big brand generator is the only option that makes sense (to me). They are well proven, with a huge experience base and engineering behind them (diesel generators must be one of the most prevalent and perfected artifacts of 'modern civilization' next to the assault rifle). But under 5kw there is not such a commercial market or base and the commercial offerings are less good and the 'school bus' approach makes more sense. I don't think that DockH has detailed his proposed electrical requirement, which would include at least (a) desired max gen run time/day and (b) maximum Kw's needed during that run time, so we don't know where he falls on this spectrum.

2. If you are building a 'mostly electric, mostly charged by diesel' solution, then to get maximum system reliability, probably the highest leverage placed to focus your attention is in fact not on the actual generator design (which are pretty damn good), but rather (a) on maintenance access to the gear and (b) the fuel system (the most likely single point of failure in a multi engine diesel approach).

Excellent maintenance access requires a significant space allocation. Dashew's own 80'er has spectacular maintenance access. That 64'er, while quite good compared to most 'yachts', is very cramped compared to Dashew own boat. An approach here which I have used in helping a couple owners is to start by building a detailed 3d CAD drawing of the equipment space (a couple times then going to an actual physical mockup) . . . without imposing any vessel size constraint on the space. Making sure that it is 'an engineer's dream' - as compact as possible while still allowing truly excellent access to everything (and you need to get into the detailed weeds of some of the gear to understand what parts might need access, like the stupid backwards water pumps on yanmars). And then, only then, use that space requirement to essentially determine the size of the vessel.

Regarding fuel systems . . . . there are a couple possible different philosophies. Personally I like the 'large isolated gravity day tank' solution, because it gives you protection from contaminated fuel and from pinhole fuel/air leaks and from pump failures. To execute it you just need to design a filtering system between the main tanks and the day tanks that is truly bulletproof - for instance will not let water pass even if it is overwhelmed by water in the main tanks, and will not let the day tank run dry without multiple operator errors.

3. Ultimately, always on diesel fuel cells seems like the ideal solution, but today the methanol EFOY fuel cells have a time between factory service of about 5000 hours, which is fine for the racers but only 200 days for a cruiser. So there would appear to be quite some development required before they are really ready.

But I might mention that there is another 'quiet always on' generator option that is available today - the sterling engine whispergen. If you plan to cruise in areas where you would need heating, and you do not need massive superyacht amounts of electricity, this is a decently attractive option. It has not had much marketing, and you would want to carry pretty comprehensive spares because otherwise you will have to get parts fedexed from NZ, but it is close to an ideal solution if you fit in their narrow niche.

4. Finally, I might comment that my personal sense of an important aspect of obtaining maximum reliability is focus on absolutely minimizing and simplifying your demand. I have written articles on that. But It's probably not worth discussing here because I have the strong impression that DockH wants to 'take everything with him' and is not interested in strongly simplifying. There's no right answer to this - Each to his own - but it does help reliability.

Thanks; incredibly useful thoughts

I probably need to work up a power budget to do this right. My thoughts so far are directed by the electrical budget on my present boat + fully electric cooking.

I presently have a 6.5kW Kohler low speed heavy duty AC generator and a 110 amp * 24v school bus alternator on the main engine, and I have 0 wind or solar, so all the power is made by burning diesel.

My background with electrical power is that my Father was a real power nazi on his boat (water, too), and I hated that regime where every watt-hour was counted. He even made me use the foot pump in the galley to save power on the fresh water pump!! He even counted the time that mobile phone chargers were connected. I swore years ago that I would have abundant power on my own boat and never impose that kind of regime on anyone.
So we live reasonably large in terms of power – inverter is on 24/7, quite elaborate nav and instrument network powered up 24/7, often 5 or 6 people on board so up to 20 mobile devices being charged at the same time, electrical power used for boiling water, microwave, etc., etc., up to one load of laundry washed and dried every day, and so forth. We don’t scrimp on power. Yet the existing system with modest battery capacity (420 amp/hours * 24v) copes just fine. One generator run a day of two to four hours does it when the batts were reasonably new. We just don’t worry about power.

Therefore, I wasn’t looking for any radical changes for the next boat except to make the system more field serviceable and more robust, if possible. One thing for sure is multiple, ganged charger-inverters to eliminate that single point of failure is essential – we are highly dependent on that device, which is the whole interface between AC and DC.

The school bus alternator is a reasonable backup to the generator, and probably the very same setup would be ok on the next boat. Northern Lights, even the next smallest one, would be ok and I think they are pretty reliable. So am still on the fence between that or my KISS generator idea which is the subject of this thread. If we go to LiFePo batts, which is Plan A at this point, then up to the whole generator capacity can be poured into the batts, making for shorter and more efficient generator runs. In that case I guess I wouldn’t go smaller with the generator – I guess 6.5kW is about right. I would go with a larger alternator on the main engine, or maybe try to get two of them on there, to get generating capacity that way up in the range of 5kW or so. LiFePo batts would be helpful there also in creating a reasonable load for the main engine, and keeping the charging runs as short as possible. LiFePo and diesel charging go together like cookies and cream, of course; just like lead-acid and solar are a match made in heaven.

I am 100000% in agreement about fuel systems and access as top priorities on the next boat, and I have studied Dashew’s boats, and also our friend Nick’s fuel system, which he wrote up on here.

This boat will be about 65’ long, but will have modest passenger volume, probably less than what I have now on this 54’ boat. The balance of space will go over to far better deck storage, and technical space, than what I have now. In my opinion, no series-built cruising sailboat has even ½ of the deck storage and technical space you need for any kind of serious voyaging. The result of boat sales driven by passenger accommodation, I think.

So a top priority is a full-sized, walk-in engine room cum workshop, with workbench, excellent tools, parts, and fluids storage, and excellent access from all around all the systems, excellent lighting, etc. I’ve learned a lot of lessons from my present “crawl-in” engine room, which I hate. I want it to be separated from the main accommodation space by a watertight bulkhead (a la Sundeer), and I want access from above as well the sides, a la Amel. Probably it will have to be full width. Video cameras inside the engine room so I can see at a glance what is going on in there. Sea chest instead of a profusion of through hulls.

The engine room should be large enough to accommodate all of the technical systems – water maker, fuel system, etc., and should be extremely well ventilated, but charger-inverters and electrical panels will be in a separate well-ventilated cabinet.

I LOVE your idea about laying out the engine room and then designing the boat around it. PERFECT! That’s the way it should be – form should follow function. I will add that to my brief. Passengers get what is left over after you deal perfectly and without compromise with the main things, like the engine room. And deck storage. Not vice versa!

Another top priority is an excellent fuel system. Two separate plastic fuel tanks with separate fill ports, with fill ports led well above deck level (my present boat is actually excellent for this). Deck-level fuel fill ports are the work of the devil, and a guaranty of sea water in the fuel at some point. Fuel tanks with sumps and accessible drains from below, notwithstanding certain rules which forbid that. So that dregs can be drained off regularly, every few days. Fuel polishing and transfer system like Nick’s. Day tank with gravity feed inside the engine room. Two separate sets of dual Racors with vacuum gauges. Maretron N2K fuel flow meters. Fuel system set up so that known good fuel can be isolated from new fuel taken on board (hence the dual tanks and transfer system).


Concerning WhisperGen – Sterling cogeneration – this is an absolutely perfect system for a boat like mine, in my latitudes, where we always need heat year round. But these were never perfected, as far as I understand, and the factory was never rebuilt after the NZ earthquake – is that not true? I don’t have this in my brief only because I was sure it’s not available. I would even install one on my present boat if I could get my hands on one.


As to eliminating equipment and comforts – I live and work (I'm not retired) a significant part of the year on board, and I’m not interested in camping. If I were designing a boat JUST for Arctic expeditions, the brief would be quite different. Enough said on that issue.

[estarzinger]

Originally Posted by Dockhead

Concerning WhisperGen – Sterling cogeneration – this is an absolutely perfect system for a boat like mine, in my latitudes, where we always need heat year round. But these were never perfected, as far as I understand, and the factory was never rebuilt after the NZ earthquake – is that not true?

I could be wrong, because I have not looked into it recently, but I had thought that they closed NZ and reorganized operations to Spain and refocused on the RV/residential market - Whisper Tech operations move to Spain - business | Stuff.co.nz.

I was told (a decade ago by an owner building a dashew design in NZ) that the RV model was 'marinized enough', and I know they have used the unit while cruising in Chile).

But I have not looked at Whispergen in a couple years, as they are/were expensive and most owners prefer to put the money and space into a much higher kw genset.

It sounds like you may well be in 'the grey' zone (5-10kw) where it is not so clear whether the KISS or commercial gensets are better.

BTW, one other random observation . . . . I dont have much personal experience with this . . . . but the commercial skippers I know say that actually (and surprising to them initially) the more electronic the genset/engine, the easier/faster it has been to resolve problems. They have to carry spare boards but all they have to do is get the boards out of storage and plug them in. That is easier to accomplish than delicate mechanical work.

[Dockhead]

Originally Posted by estarzinger

I could be wrong, because I have not looked into it recently, but I had thought that they closed NZ and reorganized operations to Spain and refocused on the RV/residential market - Whisper Tech operations move to Spain - business | Stuff.co.nz.

I was told (a decade ago by an owner building a dashew design in NZ) that the RV model was 'marinized enough', and I know they have used the unit while cruising in Chile).

But I have not looked at Whispergen in a couple years, as they are/were expensive and most owners prefer to put the money and space into a much higher kw genset.

It sounds like you may well be in 'the grey' zone (5-10kw) where it is not so clear whether the KISS or commercial gensets are better.

BTW, one other random observation . . . . I dont have much personal experience with this . . . . but the commercial skippers I know say that actually (and surprising to them initially) the more electronic the genset/engine, the easier/faster it has been to resolve problems. They have to carry spare boards but all they have to do is get the boards out of storage and plug them in. That is easier to accomplish than delicate mechanical work.

Fascinating data point on electronics. A highly respected diesel expert told me the same thing about propulsion engines. Said common rail is far more reliable and better in every way. He said there is nothing which can't be fixed on a common rail engine with a spare PCB and a spare pump/injector unit.

So I'm considering the Yanmar 160hp six cylinder common rail engine for main engine.

With Hundested variable pitch prop.

Sent from my D6633 using Cruisers Sailing Forum mobile app

[Dockhead]

Northern Lights take the opposite approach from the "more electronic = more reliable and more easy to service" one. Their specification sheet:

http://www.northern-lights.com/media...heets%20V1.pdf

says:

"DC system uses reliable relays instead of an unrepairable printed circuit board"

Does anyone know what that really means?

There is no control board at all, just relays?

[pdf27]

Originally Posted by Dockhead

But in practice, marine diesel engines are extremely reliable and extremely serviceable after 100-odd years of development.

And electric propulsion -- although it has existed for as long as diesel propulsion has -- is not well developed in this size class, and what is available is pretty experimental.

That's the big issue - marine diesels are usually derivatives of land-based engines with a few tweaks to make them suitable for the application, meaning that they've been built in huge numbers and the issues are well understood. That means the issues with reliability have by and large been found and designed out.
Electric motors themselves are probably in wider use worldwide than diesel engines for various industrial applications. Unfortunately those interested in electrical propulsion always seem to be trying to get rid of the gearbox, and that in turn means they always feel the need to go for high torque/low speed motors - which in turn they usually have to design themselves because there isn't much of an industrial market for them!

Digressing completely, I do wonder whether digging the guts out of a Nissan Leaf might be quite a good option for someone willing to take a few risks and who doesn't go far from shorepower: it'll be vastly better developed (and cheaper - there are several used Leafs out there for £8,000 with pretty low miles) than a lot of systems out there and the battery is big enough to run the rest of the boat too.
The motor is 80kW and 35 Nm of torque at 16,000 RPM (cooling limited to short periods of time - not a problem with lots of cooling water available!). With say a 5:1 step down gearbox you've got something roughly equivalent to a 70 hp engine in very roughly the same weight and bulk but with no need for servicing and minimal fuel costs.

[Dockhead]

Originally Posted by pdf27

That's the big issue - marine diesels are usually derivatives of land-based engines with a few tweaks to make them suitable for the application, meaning that they've been built in huge numbers and the issues are well understood. That means the issues with reliability have by and large been found and designed out.
Electric motors themselves are probably in wider use worldwide than diesel engines for various industrial applications. Unfortunately those interested in electrical propulsion always seem to be trying to get rid of the gearbox, and that in turn means they always feel the need to go for high torque/low speed motors - which in turn they usually have to design themselves because there isn't much of an industrial market for them!

Digressing completely, I do wonder whether digging the guts out of a Nissan Leaf might be quite a good option for someone willing to take a few risks and who doesn't go far from shorepower: it'll be vastly better developed (and cheaper - there are several used Leafs out there for £8,000 with pretty low miles) than a lot of systems out there and the battery is big enough to run the rest of the boat too.
The motor is 80kW and 35 Nm of torque at 16,000 RPM (cooling limited to short periods of time - not a problem with lots of cooling water available!). With say a 5:1 step down gearbox you've got something roughly equivalent to a 70 hp engine in very roughly the same weight and bulk but with no need for servicing and minimal fuel costs.

Sounds like something which would be fun . . . to read about.

[Pyxis156]

Dockhead,

I haven't chimed in because it seemed you were keen to go a primary engine / genset route but in light of your interest in the Dashew approach and the following quotes, I thought my experiences might be a useful datapoint:

Originally Posted by Dockhead

What you write actually follows the systems architecture principle which is at the heart of what I'm doing here -- use the same source of power for as many different systems as possible, the make that source of power as robust and redundantly supplied as possible.

Originally Posted by Dockhead

Fascinating data point on electronics. A highly respected diesel expert told me the same thing about propulsion engines. Said common rail is far more reliable and better in every way. He said there is nothing which can't be fixed on a common rail engine with a spare PCB and a spare pump/injector unit.

So I'm considering the Yanmar 160hp six cylinder common rail engine for main engine.

With the exception of voyaging in the arctic, our boat is similar to your desired specification with both my wife and I working remotely when we are on it and no desire to be frugal with the power. When we bought it, the boat had a 1000Ah AGM battery bank (Mastervolt) with two Electrodyne GE150-24V brushless alternators on a custom mount attached to a Yanmar 4JH4-HTE 110HP engine. The alternators were controlled by Balmar voltage regulators and the system was designed based on the Dashew system. The system worked pretty well for the previous owners but there were some issues with the voltage regulators burning out. After buying the boat, when my wife and I sailed it from San Francisco to our home port in Puget Sound we had the regulator burn out again and we unfortunately did not catch the problem immediately leading to the batteries being damaged. This led to us replacing the batteries last spring with an OceanPlanet Energy / Genasun 1080Ah LiFePO battery bank. We also have 540W of SunWare solar panels you can walk on in 10 panels mounted to the hard dodger top and deck, and a SuperWind 350 wind generator. The system also maintains the stock 12V alternator for charging the separate engine battery.

After our first year of use, we are extremely happy with this system. While we were impressed with the alternators when we bought the boat, they have really come into their own with the Li battery bank. The alternators are rated at 150A each but put out about 340-350A (8.4kW) at typical cruising RPMs and at 2800-3000 RPMs I see a max output of about 375A (9kW) or 125% of rated output and they have done this for hours without breaking a sweat. This now means that in a typical 3-5 days we spend in one place while cruising the batteries may reach 20-30% SOC and then running the engine for 1.5-2 hours while moving to a new site brings the bank back to full charge, and I mean 95-100% SOC as there is no practical charge taper with these batteries until about 98% SOC.

My understanding is Electrodyne's primary market was (is?) US military and these alternators are designed to be incredibly robust. Being brushless, the only real point of concern might be the diodes exposed to heat and to address this Electrodyne mounts the diodes remotely. When we bought the boat, I called Electrodyne to ask if there was any type of service I should perform since there was a little over 1,200 hours on the engine / alternators and five years since they were installed. The engineer I spoke to paused thoughtfully and then said "Nope, in that application you might want to check the bearings at around 20,000 hours, but that's about it". I exaggerate not...

So given that background, our setup seems like it could fit your original premise of using "the same source of power for as many different systems as possible, then make that source of power as robust and redundantly supplied as possible." As you stated previously, the modern common rail diesel is extremely reliable and field serviceable. With two primary charging alternators and individual voltage regulators, you have some system redundancy from a DC power generation standpoint. And replacing an alternator, voltage regulator or remote diode pack is a pretty simple operation if it becomes necessary. You also have only a single engine to stock parts for and maintain. The fuel system is also somewhat simpler with fewer filters to maintain and less plumbing to run than a engine / genset setup.

Attached are a couple of shots of the alternators, the first pre-install so you can see how they are mounted to the engine and the second mounted in the boat during construction. In the second photo you can also see the redundant Racor fuel filters, the two on the left between the day tank (bottom right of photo) and the engine and the two on the right between the four bunker tanks and the day tank.

Hope this helps... happy to answer any questions.