Quietest Small Diesel Genset

Hi all,
I have space for another generator and was thinking about doing something super small that can essentially keep up with the inverter and keep the batteries charged. I currently have an NL12kw.

Are there any ultra quiet small (3-5kw) generators or is it light outboards where size means quieter?

Thanks

We have a NL 5 kw in a sound enclosure that is very quiet and a fuel miser. We run it 24/7 when not on shore power. The Lugger engine is smaller than my riding mower, 2 qt oil change.

The Victron generator test of a few years ago found the small Northern Lights to be the quietest. Victron tested European models which are not exactly the same as NA versions, but the relationship between brands should stay the same.

HiDHo said:

We have a NL 5 kw in a sound enclosure that is very quiet and a fuel miser. We run it 24/7 when not on shore power. The Lugger engine is smaller than my riding mower, 2 qt oil change.

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We had a NL 5Kw for 10 years on our last boat and loved it. It was quite, sipped fuel and it had good international support. I’d had issues with the factory exhaust elbow till I changed to a stainless steel one though.

I have had 2, Onan 4kw and Westerbeke 4kw. The sound shield is the key. The one for the Onan was quiet enough that the fridge running down in the galley completely masked the sound of the Gen running.
The Westerbeke has a differently designed shield, and is also quiet, though not less than the fridge.

Just as noisy, or sometimes more noticeable, is the soft splashing of the exhaust just below the wheelhouse door. If that was a few inches lower, or routed out the stern, it could be quieter. In very calm conditions, the door will be kept closed to guard against fumes becoming noticeable, which also helps with noise abatement.

All in all, not enough noise to be of any concern, with a good, factory issue sound shield.

http://aquamarineinc.net/minigen.php

Aquamarine Inc. PO Box 55, Deer Harbor, WA 98243-0055 USA
Ph: 1-800-376-3091 or (360) 376-3091 fax: (360) 376-3243
All rights reserved. aqua2133@me.com


These guys sell a 1 or 2 cylinder Kabota with a 150-200 amp 12v alternator. Various configurations that can include a watermaker. The amp output should run most inverters.

6 kw for me

Arthurc said:

Hi all,
I have space for another generator and was thinking about doing something super small that can essentially keep up with the inverter and keep the batteries charged. I currently have an NL12kw.

Are there any ultra quiet small (3-5kw) generators or is it light outboards where size means quieter?

Thanks

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I have a 6kw and 12kw NL. The 6 will run the charger and an ac, and stove and washing machine. The 6kw was installed in 2011, the 12kw installed when boat was commissioned in 2003. Now the 6kw has 2050 hours and the 12kw 1850 or so. Both generators produce about same noise level.

Gordon

A gas water separator will eliminate all the splash from a generator exhaust, something like this:

2" X 2" X 1.5" Gen-Sep - Centek Industries

koliver said:

Just as noisy, or sometimes more noticeable, is the soft splashing of the exhaust just below the wheelhouse door. If that was a few inches lower, or routed out the stern, it could be quieter.

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I completed my NL 5kw last year, sound shield, underwater exhaust. I was rather pleased when at the park dock when a fellow stopped, hesitated, and then commented “Is that your generator running? I can hardly tell”. I’ll admit to smiling.

Arthur: I know this is slightly off topic, but are you sure you need a second generator?

https://mvdirona.com/2018/01/two-generators-when-you-only-have-one/

It’s NOT an Entec West Generator! We call her thumper!

JDCAVE said:

It’s NOT an Entec West Generator! We call her thumper!

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My circa 1980 Onan MDJE 7.5 is affectionately known as "the tooth rattler." With the water-lift muffler you can hardly hear it outside the boat, but the vibration inside is enough to loosen your fillings.

CaptTom said:

My circa 1980 Onan MDJE 7.5 is affectionately known as "the tooth rattler." With the water-lift muffler you can hardly hear it outside the boat, but the vibration inside is enough to loosen your fillings.

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I feel your pain.. we have the same unit.

its off topic but..
Has anyone re insulated their genset enclosure with any better results and with what material?

HOLLYWOOD

got a NL 5kw that is at about 5000hrs. Had to decarb and do a valve job, otherwise has been a trooper.

Believe it or not, the 3cyl machines are more social than the 4cyl. 4cyl has a nasty second order vibe that is hard to isolate with soft feet or soundbox.

I did not bother with a soundbox. In pilot house and cabin it is just a gentle purr. It makes for super good sleeping. No need to be quieter.

"but the vibration inside is enough to loosen your fillings."

IF you have the room its an EZ fix,

Mount the noisemaker with soft mounts , suitable for its weight,on a robust metal frame.

Mount the metal frame to the vessel with soft mounts suitable for the total weight.

Be sure all connections can handle the full range of motion, including the exhaust.

hollywood8118 said:

I feel your pain.. we have the same unit.

its off topic but..
Has anyone re insulated their genset enclosure with any better results and with what material?

HOLLYWOOD

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I removed the light soundproofing material in my enclosure and replaced it with some heavy lead lined Soundown material. I bought one sheet 54” x 8’. And it was plenty to redo the enclosure with some left over for some small hatches. With the peel and stick option the cost was $176.50 + freight for the big sheet.

It made a difference, but the biggest difference were the soft mounts I installed under the generator instead of mounting the genset directly to the wood platform. Also got those mounts from Soundown.

We did an upgrade last year to Fisher Panda, they are amazingly quiet and vibration free due to the design as it it fresh water cooled and has a cool clam shell cover. We also did the GenSep on it which furher quiets the unit down.

We had an onan prior and the difference is night and day, honestly you cannot tell on our boat that it running (which has a different issue, we forgot to turn it off one night)

Highly recommend you check them out as many people are not aware of the unique design approach they have taken

https://fischerpanda.com/

CaptTom said:

My circa 1980 Onan MDJE 7.5 is affectionately known as "the tooth rattler." With the water-lift muffler you can hardly hear it outside the boat, but the vibration inside is enough to loosen your fillings.

Click to expand...

We had the same problem with our MDKD and replacing the three motor mounts (not at all expensive) stopped it completely. It's an easy job if you rent a PortaPower (we now carry one onboard) for a day and lift the motor from underneath (about 1.5") with the duck bill attachment, once you've removed the bolts.

Fisher Panda super quiet and cool running

Last year we upgrade from Onan 12kw to Fisher Panda 15kw. The fisher panda units are smaller, lighter, very low vibration due to the double motor mount design, and super quiet as unit fully enclosed with no air requirements as the entire unit is fresh water cooled, which also helps keep the engine room or area you have it cooler.

We also did the GenSep which make the unit even quiter when on the back deck.

https://fischerpanda.com/

Highly recommend you take an open minded look at there solution as it a different approach then any other generator on the market when we did our research on this.

only weakness, it is so quiet we have forgotten to turn it off a few times.,

The Nextgen 3.5 is quiet with the sound-shield in place.

Comments about Phazor. Getting good press here in FL

I had a 15kw Phasor in my last boat with the very quiet Kubota engine. loved it one of the quietest genny's I have come across.

What about solar and/or an EFOY fuel cell generator? Then you have absolute silence! Oop, sorry for that loud exclamation point.

Hey Cap't Tom, appreciate your comments on 1980 Onans

When my 1980 MDJA 3kw Onan generator comes on the whole boat shakes from the initial explosion. When it finally warms up though it is very quiet on the outside with barely a flutter of water exiting from the exhaust. The vibration rattle is more noisy inside the boat.

Here is the only thing I am sure of: Don’t buy a single cylinder
Generator of any brand. You will hate it.

We recently replaced the tired original 9kw Kohler with a 4.5 Phasor. Half the weight, a third of the noise, and more delivered power. Would recommend the unit.

I also can recommend Phasor. I had the 15kw unit. In 7 years of cruising 6 months a year it provided faultless performance. It was also noted for being the quietest unit available.

Rossland said:

Arthur: I know this is slightly off topic, but are you sure you need a second generator?

https://mvdirona.com/2018/01/two-generators-when-you-only-have-one/

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The Dirona owners designed and operate their boat like a commercial ship. The Auto Start feature he installed to power up the Gen when their batteries hit 55% was a great idea.

For this use solar is perfect. Much cheaper, more reliable, no maintenance, no noise.

Add Firefly batteries and a 210 Efoy. The Fireflies will give you 370 of usable amps to power what you have described.

The Efoy for the Pacific Northwest, coastal BC and Alaska Pan Handle will work like a charm in cloudy rainy days, out performing solar, hands down.

Not cheap, no noise, peace of mind. Your situation is a classic case for an Efoy.