Any live-aboard cruiser who is considering a lifestyle that will require more than about 3 kW hours (regardless of voltage) of electricity daily should at least consider a generator.
I emphasize “about” because numbers like this vary based on usage profile. For example, the number where a generator makes sense is:
- Less for people like Phyllis and me who abhor the clutter, windage and vulnerability to storm damage of more than a couple of securely mounted reasonably sized solar panels.
- More for those willing to take the windage and associated sailing performance hit of large solar arrays and even wind generators.
The other benefit that many cruisers are not aware of, including me until Eric Klem sorted me out, is that when done right generators are over 20% more fuel efficient than an alternator running off the main engine while underway, and even more at anchor, as well as more efficient than Integrel when not underway—yes, even when we take into account the losses in the chargers to convert from AC to DC.
The other surprise is that a really good generator installation can save fuel and be greener when compared to renewables. I know, hard to believe, but see Further Reading for why.
So let’s dig into how to efficiently generate a bunch of power using a generator, based on my nearly 30 years of doing just1 that on our McCurdy and Rhodes 56.
Why The Big Deal?
At this point, many of you are probably wondering why I’m making such a production out of this. Surely we just install a generator and have near unlimited power, end of story?
Yes, that works, but the problem is that generators burn the least fuel per kW hour (highest efficiency) when running at about 75% load, but that’s not how most users run them.
Instead, many electricity consuming loads are installed on the boat—electric cooking, fridges, freezers, icemakers, air conditioning, etc.—and the generator is sized to supply everything all at once and charge the batteries at the same time.
But most of the time only a few of those loads are actually on, so these generators are often run for hours or even days under tiny loads, resulting in 20 to 40% more fuel burn per kW hour of electricity produced2.
That’s horrible for the planet and our wallets. And, further, running a diesel engine lightly loaded is seriously bad for it, more wallet damage.
The Best Solution
Obviously the least expensive and greenest solution is to simply cut our consumption to the point where a seamanlike renewables array can do the job, supplemented with charging from the main engine when underway anyway, and perhaps an occasional charge from the main engine when anchored.
A Good Solution
However, many cruisers these days want at least one of, and often several of, the following:
- Electric cooking
- Washing machine and dryer
- Big freezer—Phyllis’ and my environmentally bad habit
- Watermaker
- Air conditioning
- A huge array of cool electronics including Starlink
- Big autopilot
- etc.
So for us that conservation solution is not going to work.
What We Need
So what do we need to use a generator efficiently?
Could you give us a little more detail, John, on your reliability concerns with the DC generators like the Fischer Pandas? Is it with the diesel engine? Or the DC generating component? Or the electronic control system? Something else?
If the little 2-cylinder models are routinely run for more than a couple of hours at near maximum load instead of staying under the recommended 80% maximum load for long runs, then I think that I’d be concerned too how long they will last running at full load at or nearly at 3600 rpm. However, the larger 3 and 4-cylinder units, while still being lighter than a Northern Lights that produces fewer kW, run at least 600 rpm slower, so maybe if those Kubotas are generally kept under the 80% load recommendation they can be expected to last longer?
I can also seeing longevity suffering if installation and maintenance details are not attended to, but are these DC generators any more vulnerable to bad fuel, oil, air or inadequate cooling than are fixed rpm AC gensets?
Some things are really attractive about standalone DC generators or main engine systems like Integrel or the similar hybrid offerings from Beta Marine, so I wish I had a better handle on where the reliability concerns are coming from
Hi Mark,
The small diesel generators are just not as ruggedly built as a commercial level unit like the Northern Lights. They are also far more complicated with many more sensors and finally we have many anecdotal reports of problems with both DC Generators and lightly built variable speed AC units.
This would be much the same as the difference in reliability and longevity between a commercial grade engine like a John Deer and lightly built engine like a say a recreational Yanmar. (Yanmar build commercial engines too, or at least used to.) The Deer typically goes 20,000 hours before rebuild and the latter is generally done after less than 5000 and usually not rebuildable.
So I’m not saying a DC generator is a bad solution, just that a Northern Lights is a better one for those who have the room and can tolerate the weight and one I can pretty much guarantee based on my own three decades of experience and that of a friend of mine who fitted them on his fishing fleet where they ran 24/7. Also a lot of the above is based on the experience of my friends at Billings Diesel and Marine.
And sure, if we don’t install them right or abuse them, either will cause problems, that’s a given, although the NL probably less because it’s more ruggedly built.
As to Integrel, we have complete review on that, which I have recently updated, that deals with reliability and compares to a generator. https://www.morganscloud.com/2019/02/13/nigel-calders-generator-replacement-machine-part-1-what-you-need-to-know/
Hi Mark,
I am a firm believer that, for boats the size of Alchemy, 40 feet, that a DC genset (GS) is the way to go.
I turned Alchemy into a DC boat (the occasional need for AC covered by an inverter). And for 15+ years I nursed an Ample Power Genie DC GS until I had stripped off all the stuff that made it complicated and it was essentially a small Kubota engine attached to a big alternator. But it was way too often a headache, often in remote areas.
During our wanderings I ran into a handful of boats using the FP DC genset (GS). All had had numerous reliability problems. Two had turned their unit into mooring weights (as they described it). More than one had spent thousands and lost much cruising time waiting for help. I believe one cruiser was making his work for him, but I have not heard from him in years about his experience. A mechanic for an RNLI station in England where the rescue boat had an FP GS said the majority of his time was spent keeping the FP going.
As to the reason the FPs have reliability problems: one said it was way too complicated and compact and said it would be like taking a BMW engine (where you lift the hood and there is engine in every nook and cranny) and taking it into a salt water environment.
It does not seem rocket science to have a small engine attached to a big alternator with a good regulator. And they exist, but the few I know of are all bespoke: creative mechanically knowledgeable cruisers making it happen. Beyond that, there is limited demand: AC GSs are used all over: not just in boats. Very limited market for DC GSs.
There are a couple of DC GSs to be found: one from FL sounded good but getting any information from the owner was impossible. He would not say how many had been built nor would he put me in touch with any owners who had history with the unit. Everything was proprietorial. One other had limitations and none had a track record that I could determine.
I believe a generator on my size boat finds justification by the skipper wishing to have AC at anchor or by having a large freezer. I have no AC but I do have a large freezer which allows us long periods away from provisioning while still eating as usual (we do not wish to ”camp” out.)
Failing finding a DC GS, and not wishing to shoe-horn in a big Northern Lights (casual research indicated that insertion might be possible, but maintenance and or repair would be very challenging), I have gone with a Next Gen AC GS, a small Kubota engine (3kw) attached to a back-end putting out AC. This fits very nicely (no sound shield) and has worked well through 3 seasons. I am working on a write up of the unit.
Come back with questions.
My best, Dick Stevenson, s/v Alchemy
Hi Dick,
Thanks for adding your experience with DC generators.
And good to hear the Next-Gen is working well for you. Sounds like a nice middle ground between the FP and NL and a good alternative for smaller boats.
Great discussion. I’m a big fan of the next gen. I have the 5.5kw which is a 2 cylinder commercial Kubota (same as in most refrigerator trucks) turning at 2800 RPM. It’s a nice middle ground between the NL which would be too large/heavy for my boat, but it’s not a lightweight 3600 RPM screamer or complex FP.
It’s very reliable and robust- with only a few standard shutdown sensors (oil pressure, etc) that are easily visible. The only rare failure point is the capacitor which I blew once (my fault) and is easily swapped.
When cruising, I will most often bulk charge and run the AC water maker at the same time for 1-2 hours- and also can make hot water or use AC
I too have heard good things about the Next-Gen 3.5kw AC unit based on the single cylinder Kubota block. I can’t say the same thing for any other generator in that power output range and size.
Given the Next-Gen comes in at 160 lbs without an enclosure (200 lbs with) and is 28L x15.5W x15H vs the Northern Lights at 371 lbs and 27.5L x 16.7W x 20.5H and I’m guessing around $10-12k more, I think it is a good option – particularly if you’re expecting to motor some of the time which would give you some extra charging.
Hi John and all,
You pegged an ongoing concern of mine with AC gensets (GS): loading them up sufficiently if the boat is a DC boat and the genset is primarily used for charging the batteries.
On my AC genset I run 2 battery chargers: Mastervolt 75A and 100A. The output starts at 140+ but drops down to 90A or so in 10-15 minutes. At 80-90A a 3kw GS is not exactly loafing, but nor am I getting the amps into the battery as fast as I would like or using a better percentage of the 3kw capacity.
I can and do turn on the water heater to load up the GS, but I would far rather load up the GS by getting more amps into the battery bank faster and running the GS less time.
Much appreciate any thoughts.
My best, Dick Stevenson, s/v Alchemy
Hi Dick,
Yes, I have seen that behaviour before where the chargers drop below rating quite quickly. This might be because they don’t have separate sense wires and there is a voltage drop between the chargers and the batteries. This can result in the chargers thinking that the batteries are more charged than they are. Worth checking the voltage at the chargers and that at the batteries. Might also indicate that the batteries are sulphated. They should take full charge up until about 70% fully charges, if not that’s a pretty sure sign of sulphate on the plates.
The other option is that the charger software assumes a fixed time acceptance ~14.4 and therefore drops off shortly after the bulk phase ends (voltage reaches 14.4).
More here:https://www.morganscloud.com/2010/09/04/agm-battery-chargers/
When I ran a yard in the late 90s and early 00s I was an enthusiastic believer in an all DC boat, with a DC gen. I set several up, including Dick Stevens’, with both the Ample (I was an acolyte of Ample’s founder, Dave Smead, starting in the early 90s after attending one of his seminars, and reading his books about living on DC power, at the time their alternator regulator was way ahead of its time) and FP DC gens, as well as one called a Polar Power. In theory, this should work, however, in practice, it was mostly a failure for the reasons John states, among other things low production numbers = low reliability. While today’s DC world has advanced immeasurably, with high output alternators and big inverters, becoming the norm, and LFP batteries becoming almost standard on new cruising vessels, power and sail, a mass produced AC genset like a Northern Lights is still the most reliable way of producing electricity aboard, and the fact that it is independent of the propulsion engine is, in my opinion, a redundancy advantage.
Hi Steve,
Thanks for coming up with a clear and concise analysis. Your process of disillusionment with DC generation is much the same as mine, although yours is almost certainly based on more experience. I too was a huge fan of Ample Power back in the day. I even thought about taking out the NL in favour of the Ample. Very happy I never did that!
For others: few people, if any, have even close to as much experience with different types of electrical generation as Steve does.
Thanks, Steve. I’m curious about your experience with Polar Power. They’re still around, and have caught my attention for awhile because, on paper, their product looks interesting — but I’ve never heard from anyone with actual experience. Part of what makes them interesting is that they are the only DC genset manufacturer that I know of whose documentation states that their generators can be derated and run significantly below the ~3000 rpm mark, and they recommend doing so when trading increased weight for better longevity makes sense. Doing that means that there is no weight advantage in going with one of their DC generators instead of a fixed rpm AC genset, but I’m curious whether the longevity promise of a Volvo Penta running around 1600-1900 rpm would be enough to persuade you to take another chance with Polar Power, or whether your prior experience and ongoing concerns like limited production and distribution would still make you shy away.
Another well written article with concise and straight forward advice.
Hope this is not too off topic but it might be of value for those cruising in smaller boats. My wife and I are not liveaboards on our 32’ trimaran but we do live aboard when we take off on our 2-3 week cruises. We carry a Honda 2200CI gas generator and we only use it for heat and A/C as needed. We will never plug the boat’s shore power system in to this generator. We have a Frigidaire window AC unit that we mount into a companionway hatch adapter we built that when set in place is powered by either shore power at the marina or the Honda generator at anchor. We have a small Caframo True North heater that also plugs into the generator or shore power when we need heat. The generator is always set up on one of the boat’s amas which is effectively 13.5 feet distance from the cabin companionway and completely open so no CO risk (the generator also has a CO monitor for insurance). We will get 8-10 hours of run time on less than a gallon of fuel when operating either the heater or the A/C unit continuously. Our boat has a built in 12V refrigerator and an Engel 12v freezer that lives in the aft cabin of the boat. So far, our solar panels and Yanmar diesel engine have covered our battery charging needs well. The generator and the five gallon fuel tank we carry for it and the A/C unit both have storage bags and are placed in the boat’s ama’s when we are underway. The distancing of the generator from the main cabin due to our boat being a trimaran is a distinct advantage. This Honda generator is incredibly quiet (about 59 dB) and when running, you will really not hear it until you are about 20-30 yards from the boat (downwind).
When I retire in a few years, we hope to upgrade to a larger tri or cat and we may be looking at adding an onboard installed genset. This article will certainly be highly valuable at that time. Thanks John!
Hi Bob,
Sounds like a good way to use a portable generator. As you point out this works particularly well for you because on your trimaran you can get it well away from the accommodation when running and you have a safe and watertight place to keep it and it’s fuel, away from main hull. Anyway, good on you for recognizing the dangers of plugging the boat into it, and not giving in to the temptation to do so.
Two upgrades we made to our electrical system had the added benefit of making our (very old Onan 8kw) AC generator more useful: a lithium house house bank, and a second battery charger that could handle 120-240 AC as the input. The primary motivation for the second battery charger was to have a shore power solution in Europe, but when away from the dock (most of the time) we use it as additional load on the generator.
The generator never felt like a good way to charge our lead acid batteries, because their acceptance quickly dropped and we didn’t like to let them stay discharged for very long. I kept it in service but joked that I was just waiting for it to fail so that I could remove it and put the space in the engine room to better use. Now with lithium, I’m more attached to it. We don’t worry about the lithium being in a partially discharged state so we can schedule our generator runs for when it is most pleasant and convenient.
As the generator is still a bit big for our needs, I try to run it when we have some other electric loads we can put on it too; often when we want some hot water water for showers or if we plan to run the microwave or our small portable induction cooktop for awhile. (Incidentally, all these things run happily off the inverter too, so we never have to start the generator *just* for hot water, for example).
Hi Raj,
Sounds like a good set up, and very much in line with my thinking and our usage on the McCurdy and Rhodes.
Hello John,
Regarding Fischer Panda, they are next to the variable RPM DC (and also AC) that have a certain complexity there is a range of fixed RPM AC units with Kubota diesel engines. These are widely used on military and emergency applications.
When used correctly following instructions and maintenance they are reliable.
What is really bad is shutting down the diesel while fully loaded. This is where the problems of the multiple sensors can be a problem. The auto test before start checks all sensors. A good idea of having spares.
Compared to NL the FP are much lighter and support in EU (and USA / Canada) is good.
We intentionally bought a FP 8000x for those reasons in stead of our initial choice of a NL. A non responding EU reseller turned us away.
By the way we also have a Dessalator DUO 100 Navigator DC 24V and 230V) that has been very reliable and supported by excellent after sales service. So you can run it while motoring with the HO 24V alternator.
Best regards.
Denis
Hi Denis,
I guess we will have to disagree: I do so only as cruisers look to this site for suggestions and guidance. I mean my comments to be only my understanding of the state of DC gensets: everyone should do their own data collection and research.
I really wished to purchase a Fisher Panda DC generator ~~10 years ago, but research led me to far too many complaints and I was unable to find owners that were pleased and satisfied over a period of time and usage: unfortunately for us humans, it is always easier to find complaints than accolades, but I did try hard to find accolades.
Then there were the FP owners I met over the years whose experiences I mentioned in an earlier post.
You state in your post:
“When used correctly following instructions and maintenance they are reliable.”
This suggests that those who have trouble have not followed instructions or proper maintenance. I do not believe that to be the case, generally or specifically. The two owners who gave up on repair of their FPs after much effort were experienced cruisers who I have no doubt correctly followed instructions and maintenance.
I would also challenge the statement that support is good, at least when in remote areas where support had to be by phone (Belize and Newfoundland). I am 8+ years from the reports I have cited, so perhaps things have changed.
I wish everyone luck with their genset choices: they come close to mission critical for many styles of cruising and follow the nursery rhyme, loosely translated here: “When they are good they are very very good, but when they are bad, they are horrid.”
My best, Dick Stevenson, s/v Alchemy
I’ll second Dick’s comments, however, my experience is based on decades of first hand experience. I can truly say, in addition to that experience, I’ve never encountered a marine industry colleague, excluding sales people, who waxed poetic about the durability or reliability of a FP; most have worked on and repaired them, many of them. They are built to be light and compact (and cool, their electrical generation end is water cooled, which means they don’t generate hot air like conventional gensets do, which means their enclosure can be smaller and tighter, with air supplied for combustion alone), in that arena they are the undisputed leader, however, that gossamer achievement comes at a price; every time I remove the enclosure from one I feel like I’m looking at a timepiece rather than a diesel engine and electric generation system. Now, if you are saying they require more maintenance than the average genset, to remain reliable, perhaps that’s true, but why would one knowingly embrace this approach, unless your goal was the absolute smallest, lightest (coolest) package?
Whatever you do: do NOT EVER buy a small FP generator.
I bought my boat, second hand 3 years old. I managed to find some history on the internet where it was confirmed that the first owner main problems on the new boat was the FP.
When I bought the boat the FP was professional serviced, which gave me a a few hours of use, after which there were problems again.
At the end I took the damn thing out after dismantling the thing as much as possible and found out a totally chafed through + wire which could never been detected without dismantling the generator and removing the bottom plastic enclosure. (which has about every cables and tubing run through)
So that is how I find the reason that the previous owner had two maday calls made because of fire in the engine room…..
You can find on YT the channel Sail life, where the brand spanking new FP was malfunctioning with abhorrent (non) service of the company, and still after many months the problem not solved.
There is somewhere a video on YT where the owner of a small FP makes a dance of joy on the jetty after his FP was removed for good.
In short: FP sucks!
Hi John,
I completely agree that most cruisers would be best served by a 5kW genset if they have a use case that requires one yet the boats I have been on often have 10kW units. Hooking up enough battery chargers to create more than a 2.5kW load would be quite expensive and take up a lot of space but at least the big chargers are now available so you are not stringing together 5+ 40A@12V units.
In addition to the reasons that you cite for fuel efficiency, one of the big ones to me is range/ time away from a fuel dock. As I have planned various trips over the years, one of the constraints that I hate and always works its way in if the trip has a lot of mileage or is in an out of the way place is finding fuel.
For boats that need regular generator run time such as daily, I prefer to hook the hot water heater to the generator cooling circuit rather than the main engine unless you want a combined circuit which is arguably getting complex for critical stuff. Even a small generator produces plenty of heat for a 5-20 gallon water heater.
I have no experience with FP generators but everything I hear troubles me. It isn’t that hard to build a DC generator and I have done it twice but the trick is how tolerant it is of things like a load disconnect as that is best done with some level of controls rather than simply hardware. Some people build them using large alternators which I don’t like due to the efficiency hit which to me makes them inferior to AC units. I prefer to use a motor that is >80% efficient and ideally closer to 90%.
Eric
Hi Eric,
I totally agree on how vital range is. The biggest constraint on our Arctic trips, particularly to the East Coast of Greenland and Baffin Island was range and we would take huge pains to extend it including only washing when the main engine had run and the water was hot from the exchanger. I did consider adding a hot water heat exchanger circuit to the generator but in the end didn’t because finding a decent water heater with two exchangers in it proved impossible.
Talking of efficiency, the decision I long regretted was letting Ocean Options talk me out of a Hydronic heater and into an Airtronic. The former would have been way more fuel efficient because it would not have lost so much heat to ducting in the bilge. The result of that mistake was very often I rationed heating aggressively to save fuel, which did not endear me to the crew!
Hi Dick,
You are probably right. My memory is hazy about all the details but I did put quite a bit of time into it. Might have been a physical size issue. In fact I just checked and all the Isotemps are horizontal that I see, and that would not have worked for us in the space we had to fill without screwing up access to the generator…while sitting on the vertical heater.
Hi John,
And speaking of heat exchangers: it is not a substitute for other sources of heat, but friends have used what they call a “school bus heater” off their engine while motoring: lots of heat distributed by fans. And, higher latitude sailing often includes a fair amount of motoring.
My best, Dick Stevenson, s/v Alchemy
Hi Dick,
Yup, we had one of those too.
I too was an avid DC-only boat guy for many years. I’m still motivated to make it work for my own current set of cruising requirements; but the logic presented and discussed, combined with mountains of experience from key folks above is pretty unassailable.
As a roving boat yard tech for many years and the guy who frequently just somehow ‘got the call’ while sipping on a sun-downer, I became all too familiar with FP units – for all the wrong reasons. Would I put one on my own boat today? Hell, no.
But – in my work on emergency vehicles and remote power systems for off-grid applications I have seen (and used) many FP products with a reasonable level of success and reliability. Not perfect – but not abominable like you see in the marine industry. Their terrestrial systems using closed loop radiator or heat exchanger based systems seem well engineered and common on many overland and remote systems in Europe. They have an impressive hold on that niche and it is not without good reason.
but mix in a little salt water and your typical cruiser’s installation, maintenance and operation profile – and history shows the results and they’re not good.
There was a sterling-engine tech called WhisperGen that was developed I believe in NZ about 20 yrs ago that seemed pretty cool to me. Diesel fired, external combustion engine with no hammering pistons – just smoothly gliding, hermetically sealed pistons arranged around a swash plate, spinning an integrated alternator. IIRC, steady-state output was something like 80A@ 12vdc, with an additional 5kW of waste heat available for heating; all in a small package about the size of a trash compactor, and virtually silent operation. I think they sold it to a Spanish company who were putting them in remote cabins.. and I heard a rumour that the factory was wipe out in the Christchurch earthquake.
Definitely not conventional, but fascinating – 80A of almost silent DC plus heat available 24/7- that’s a serious punch from a small package.
Anyone know what really happened there and if there’s something like this being developed again?
Hi Ben,
Thanks for sharing your experience with FP, seems pretty unanimous.
I remember the Sterling well, and in fact saw one at Earls Court some years ago, and was equally fascinated, but have heard nothing since.
The issue with the WhisperGen, fascinating and historical though it was, at least in my first hand experience, was it could not retain it’s nitrogen charge. Tony Fleming installed one on his vessel, Venture, it lasted a year or two and he then scrapped it. All of the others I was familiar with went the same way. Too bad, it was viable concept, perhaps with today’s improved material technology it could be made to work. This manual details the steps for charging the nitrogen https://manualzz.com/doc/o/907rw/whispergen-pps16-12md–24md-generator-commissioning-guide-checking-and-adjusting-nitrogen-pressure?p=9
According to Don Clucas, a mechanical engineering PhD at the University of Canterbury in New Zealand whose PhD project was the origin of the WhisperGen, their factory was wiped out by the Christchurch earthquake, low volume production resumed in Spain a couple of years later, but the company and product never recovered from the global financial crisis of 2008 and “a niggling reliability issue” around the flame sensor.
Fascinating! I must explore more…
Thorough research may turn up even better resources and information, but searching for “The WhisperGen Story. A Manufacturing and Design Success or Failure?” should bring up the slides archived at the University of Canterbury of a presentation by Dr. Clucas.