Generator comparisons

Would like to get thoughts and opinions on different brands of diesel generators from those with experience with them.

What diesel generator do you think is the highest quality, and why do you think it is?

What maintenance issues have you dealt with, with yours? Brand, Age/hours is a factor here, so it may help to state that?

For those who have had warranty service, how satisfied with the service from the brand are you?

What has the support been like from the brand you use?

Thanks for any help that can be offered.

I have an 8KW Onan generator (I believe they're owned by Cummins) with a Kabota diesel engine. Been very happy with it and found normal maintenance parts easy to acquire at a very reasonable price. Would consider it of good to very good quality. It came with my boat and is 19 years old.

Regarding your question, it is great for my intended purpose, but rarely put 200 hours on it per year. If I were looking for a generator to run whenever I wasn't plugged into shore power, I'm not sure it would be my first choice.

Maybe you should indicate how many hours per year you plan to use the generator and what size you plan to buy.

Ted

O C Diver said:

I have an 8KW Onan generator (I believe they're owned by Cummins) with a Kabota diesel engine. Been very happy with it and found normal maintenance parts easy to acquire at a very reasonable price. Would consider it of good to very good quality. It came with my boat and is 19 years old.

Regarding your question, it is great for my intended purpose, but rarely put 200 hours on it per year. If I were looking for a generator to run whenever I wasn't plugged into shore power, I'm not sure it would be my first choice.

Maybe you should indicate how many hours per year you plan to use the generator and what size you plan to buy.

Ted

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Thanks! We used our previous one about 150 hours a year until we sold it last year. I will be buying another boat next year with the plan to travel more. So I would say probably 200 or so hours a year.

Northern Lights

We have a Northern Lights 9kw, which was not purchased due to our brilliant research, but rather it came in the boat. I have not OWNED other installed generators. Ours had under 400 hours when it came to us, and it is north of 800 now.

The NL is quiet and efficient, and is easy to inspect with the factory sound enclosure. I have attended the free NL class in Seattle, and I am registered for two free maintenance webinars this month. Access to NL personnel has been easy, and there are lots of dealers. Parts and consumables have been easy to find and reasonable. I have changed the oil, filters, mixing elbow, coolant, and cleaned the heat exchanger. All of this was very easy. I had a professional adjust the valves, and it was a 20 minute job. I understand there are relays (instead of circuit boards) and switches (e.g. exhaust temp) that are user replaceable and I have those spares aboard.

I often wish we had a slightly smaller unit, but I can’t tell you anything negative about our Northern Lights genset. We hope to have occasion wear it out in the next decade.

If I were building a new boat, I would NOT have a generator. We would leverage solar and battery technology with those funds.

IRENE said:

If I were building a new boat, I would NOT have a generator. We would leverage solar and battery technology with those funds.

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Depending on where you cruise, that might be a viable option. In my situation, probably 80% of use is primarily climate control (air conditioning). As you age, your tolerance to heat and humidity can change dramatically, mine did. This isn't about being comfortable, it's about being incapacitated. Lot to be said for the ability to drop the hook and recuperate in comfort if a virus of gastrointestinal distress cripples you. Solar doesn't give you that option over a generator.

Ted

IRENE said:

We have a Northern Lights 9kw, which was not purchased due to our brilliant research, but rather it came in the boat. I have not OWNED other installed generators. Ours had under 400 hours when it came to us, and it is north of 800 now.

The NL is quiet and efficient, and is easy to inspect with the factory sound enclosure. I have attended the free NL class in Seattle, and I am registered for two free maintenance webinars this month. Access to NL personnel has been easy, and there are lots of dealers. Parts and consumables have been easy to find and reasonable. I have changed the oil, filters, mixing elbow, coolant, and cleaned the heat exchanger. All of this was very easy. I had a professional adjust the valves, and it was a 20 minute job. I understand there are relays (instead of circuit boards) and switches (e.g. exhaust temp) that are user replaceable and I have those spares aboard.

I often wish we had a slightly smaller unit, but I can’t tell you anything negative about our Northern Lights genset. We hope to have occasion wear it out in the next decade.

If I were building a new boat, I would NOT have a generator. We would leverage solar and battery technology with those funds.

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Thank you for the info on the Northern Lights gennie. A generator is needed in the southeast due to the heat. I understand from reading this forum and others that many on the west coast don’t have them. Thanks for the feedback.

If I were going to replace our Onan it would be with a Northern Lights. I really think they are well made and the support seems good also.

Our Westerbeke 12.5KW had 1,700 hours on it when we sold the boat. Do not think the new owners have had any serious issues with it and have doubtless put another 1,000 plus hours on it. Seemed like reliable gear.

I just had a new generator installed. Small unit - 6kw. I went with NL.

I think some of the decision process has to be how you plan use the generator. I thought about a PTO but smallest with a PTO was 9kw.

Best I could figure, the top brands are decent - I decided the smaller ones that run at 2700/3600 rpm are not reliable long term (fisher panda, next Gen, and others). They are light, and relatively inexpensive, but in my opinion, not up for sustained use.

We have 2 Northern Lights gens with around 2,000hrs each and I wouldn’t buy any other brand. They are very well designed and built and the customer service is tremendous. Parts and available and reasonably priced.

I did have a Westerbeke on an earlier boat and it was a constant pain in the rear to keep it healthy. Parts pricing was ridiculous also, and that is twice is aggravating when you have to keep buying parts to keep it running.

mvweebles said:

I just had a new generator installed. Small unit - 6kw. I went with NL.

I think some of the decision process has to be how you plan use the generator. I thought about a PTO but smallest with a PTO was 9kw.

Best I could figure, the top brands are decent - I decided the smaller ones that run at 2700/3600 rpm are not reliable long term (fisher panda, next Gen, and others). They are light, and relatively inexpensive, but in my opinion, not up for sustained use.

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That is the one I am looking at. Good reputation, not sure about service coverage east of the Mississippi

Genny’s

We had a 2006 NL 6kw on our last boat with a sound enclosure with toolless latches on the panels. As others have said, it was easy to work on, good parts availability and was reliable. Our current boat came with a 2008 Onan 9kw with enclosure. It has also been a reliable unit, not as easy access with the enclosure- only the front panel has toolless latches. The other panels need bolts removed. I really like that this unit has a blinking code if it shuts itself down. One of the shutdown parameters is a pressure switch on the discharge of the raw water pump. If the raw water supply is interrupted, the engine immediately shuts down and blinks the code. It has done this twice, once when the strainer plugged up with grass an another when a piece of a plastic bag was sucked into the through hull. Both times this saved the impellers. I have not looked at the current generation of either mfg’s.

We had a 5KW Next Gen on the old boat and have an 8KW Kohler on this one.


The Next Gen had about 500 hours on it when it got submerged in hurricane Dennis, and I had the diesel end rebuilt then. The AC end went out a couple of hundred hours later (no surprise really) and I replaced the end with a new one that I got through Next Gen. Next Gen was GREAT to work with and the gen set ran flawlessly (well, one capacitor failure) after that for the next seven years we owned the boat.


Our Kohler had 72 hours on it when we bought the boat, though it was 8 years old. Not a good thing, IMO. But it has been pretty solid since then. We have put about 1,000 hours on it. I had to replace the controller ($900) a relay and a couple of sensors. I've kept up with the maintenance on it pretty religiously. I wouldn't say that Kohler has the greatest reputation for marine units, but I like it. Parts are easy to get and reasonable. As noted above, the temp switches and cut offs have saved me quite a few times due to clogged strainers etc. I removed the sound shield due to lack of access, but that was a mainship thing, not a Kohler thing.

My experience with Kohler has been a little different than Doug Cole's.

My 6EOD runs great, but aive had problems the twice I needed parts. The first time I waited months. The second time the part was indefinitely backlogged. I was saved by advice from a local Kohler dealer -- a Northern Lights unit had exact the same part. It was available and shipped the same day. Identical in all respects.

So I am very happy with the performance of the unit. The parts we're only needed due to an installation issue when the PO out it in.

But, I was not happy with no parts availability for a generator, never mind when there actually was availability.

Helmsman said:

Thank you for the info on the Northern Lights gennie. A generator is needed in the southeast due to the heat. I understand from reading this forum and others that many on the west coast don’t have them. Thanks for the feedback.

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I bought my boat in Chattanooga, spent a week in July there getting it ready to truck west. Both air conditioners running full blast most of the time just to stay alive. Then a lightening strike took out the power to the marina, couldn't run the genset in the covered berth and just about did die. 97 deg and raining. Trucked it to the PNW. The AC has been run for about an hour in the next 2 years, and I removed one of them.

I hate gensets. But it I lived in the southeast I'd have a big, reliable one!

Think northern lights are the best. Quiet, great even power, super easy to maintain, easy access to all service points and both tech support and parts easy to find just about anywhere. Stay away from any high rpm machine. They all stink. Match output of machine to your actual loads. Too many gensets are ruin by not having an adequate load on them or being run too infrequently. My 2 cents.

I have a NL 5kw. It replaced an Onan 15 years ago and has been trouble free, 1300 hours. If I were to buy again, it would be NL without question.

Hippocampus said:

Think northern lights are the best. Quiet, great even power, super easy to maintain, easy access to all service points and both tech support and parts easy to find just about anywhere. Stay away from any high rpm machine. They all stink. Match output of machine to your actual loads. Too many gensets are ruin by not having an adequate load on them or being run too infrequently. My 2 cents.

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That is helpful. Particularly the high RPM comment. I had 7.3e Kohler on my previous boat. Often wondered if it was really getting much load on it even with the two AC’s running.

Ken E. said:

I have a NL 5kw. It replaced an Onan 15 years ago and has been trouble free, 1300 hours. If I were to buy again, it would be NL without question.

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That’s quite a good recommendation! Thanks.

This year I Replaced a 40 year old Onan 7.5 MDJE which was probably the best and simplest Onan made. I put in a NL 9kw. Put 875 hours on it since March. Absolutely fantastic! Hasn't skipped a beat and easy to maintain.

Bigsalmonfish said:

This year I Replaced a 40 year old Onan 7.5 MDJE which was probably the best and simplest Onan made. I put in a NL 9kw. Put 875 hours on it since March. Absolutely fantastic! Hasn't skipped a beat and easy to maintain.

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Another good endorsement. Will probably go with the NL I will need to figure out size. Whether to go with a 6 or a 9.

+1 for Northern Lights in an enclosure. The gold standard in my mind. I have a 9kw.

Back in 2008, Victron did a comprehensive generator test.

https://www.victronenergy.com/upload/documents/VE_Marine_generator_test_RVA_07-jan-2008.pdf

Rossland said:

Back in 2008, Victron did a comprehensive generator test.

https://www.victronenergy.com/upload/documents/VE_Marine_generator_test_RVA_07-jan-2008.pdf

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Interesting. Looks like that study was for households. The NL came out of the study much quieter than the others. The lower RpM models were quieter, and with the additional hours of total run time anticipated does reinforce comments from others above. These are the 50hz models common in Europe. I don’t imagine there would be much difference in the 60 Hz models here.

Thanks for passing along!

I've had Northern Lights on two boats. An 8kw and a 16 kw. I replaced a start switch once and an impeller once. Hundreds of hours on them, combined. Powerful, quiet, easy to maintain. Hard to beat. Others brands are good, too. Onan, Kohler. My friend's Kohler starts easily and powers everything on his boat, including six a/c units. Never had any trouble with it except an impeller when it sucked up some mud (longer story).

MV Wanderlust said:

I've had Northern Lights on two boats. An 8kw and a 16 kw. I replaced a start switch once and an impeller once. Hundreds of hours on them, combined. Powerful, quiet, easy to maintain. Hard to beat. Others brands are good, too. Onan, Kohler. My friend's Kohler starts easily and powers everything on his boat, including six a/c units. Never had any trouble with it except an impeller when it sucked up some mud (longer story).

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As I mentioned, my previous generator was a 7.3 KW Kohler. I think though, that based upon the discussions here that I will go with a Northern Lights.

I like Northern Lights or Westerbeke. 1800 rpm and sound enclosures are a must. Generator size is easy; same size as shore power. Most 40 footers about 60 amps or 8KW.

Phasor Generator

I replaced an aging 9KW Kohler with a 4.5kw Phasor genset, Kubota powered. Wonderful unit, powers all I need, relatively quit at 1800 rpm operation. Agree with comments about avoiding high rpm units.

Take a look at the Fischer Panda Marine AC 5000. If you're a 50 amp boat this will handle the job. https://www.passagemaker.com/technical/how-to-choose-the-right-generator-for-your-boat

Westerbeke

We have a 14KW Westerbeke with about 1200 hours on it. Living in the South we use it in the hook in the summer to keep the AC cold and the fridge colder. I basically keep the belt in good shape, fresh impellers, oil and clean fuel. I like everything about it except the sound box. Too hard to reach the dipstick and oil fill. Such is life.