Quiet Genset

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Jmreim

Jmreim

Senior Member
Joined
Jan 7, 2019
Messages
172
Location
USA
Vessel Name
Boundless
Vessel Make
2013 North Pacific 43'
Looking for advice on a very quiet genset for a 34' Mariner Orient Europa trawler. Not really sure how much power I need - just running a single AC unit, fridge/freezer and small appliances (toaster, microwave, coffee maker). The boat already has an 1800 watt inverter. Plan to install a diesel powered genset in the lazarette under the aft cockpit to keep it quieter in the salon and far from the master berth up front. Any suggestions for something really quiet would be appreciated. Thx!
 
Several factors make for a quiet genset installation:

1. Pick the smallest genset that covers all continuous loads. Not so much for sound but for loading and cost.

2. Put it in a remote place. Well you have done all you can about this one.

3. Use a 1,800 rpm 3 cylinder genset. Higher rpm gensets produce a high pitch sound that is more annoying than the 1,800 one. Also 3 cylinders is a lot smoother than 1 or 2. 4 cyl is ok but too big for your needs.

4. Put it in the factory enclosure.

The Northern Lights 5 KW meets all of these but others do too.

David
 
I’m pretty sure that the Northern Lights is the quietest in that size range. That is from memory based on their advertising.

I’m also remembering that the 5KW and 8KW are the same physical size.
 
Also use isolation mounts to mount the frame to the hull, and use a gensep to separate the exhaust gas and water
 
The NL 5kw is the most socially acceptable small gennie, and a pretty well made unit. But it is probably more capacity than you need, and 350lb. It will do the job, but so would one in the 3.5kW range and the 3.5 would be lighter and smaller. But certainly less social from a noise and vibe perspective.

Got to figure out how important the noise and vibe issue is to you.

On my ride, I have an old NL 5kW and it is pretty social. But we tend to run it a few hours in the evening, then once boat is chilled down and dried out, shut it off right at sleepy time. Boat stays comfortable for 6-7hrs.

So if I had a noisy gennie it would not screw up sleep.
 
I was once shopping for a small "night generator" to run AC primarily. I was quite impressed with the Cummins Onan "Quiet" series. Easy to get serviced, and I saw some in action on a few boats. In addition, in my case, I also had an Onan 20KW main genset.
I know some folks quite happy with Phasors as well. These things in enclosures are so quiet you could have them on the other side of a bulkhead and not hear much, if anything.

I don't like the idea of a generator in a cockpit lazarette, but that is swayed by having seen a few such and they were all rusty messes.

You want something that is rated for all the loads on the boat going at once, and then up a KW or two. That way you don't have to screw around with load management.
 
caltexflanc said:
You want something that is rated for all the loads on the boat going at once, and then up a KW or two. That way you don't have to screw around with load management.
Click to expand...
Sizing to run everything or not depends on the boat. For a lot of boats, that leads to installing a too-big genset. To equal my 2x 50A/125V shore power setup (which can run everything on the boat simultaneously) would require a 12kw genset. Realistically, I could run everything on a 10 or 11kw I think.

However, I've got a 6.5kw and never really wish it were bigger. It's not terribly uncommon for me to end up firing up an A/C unit just to keep enough load on it even if I don't otherwise need the A/C. It's enough to run all 3 A/C units and the water heater (with background loads like the battery charger). That's pretty much full load, but it's also fine to run the microwave if I turn one of the A/Cs off. The electric stove isn't an issue either with just a little bit of sane load management. I could make use of a bigger genset, but only occasionally. I'd rather have the smaller unit that's a little more efficient and easier to keep enough load on instead of having a bigger unit when I only want the extra 5 - 10% of the time.
 
Technomadia on youtube recently installed a 4.5K Northern Lights unit and it is mouse fart quite on thier 4788 BL.
 
From the OPs load list, a 5Kw will be fine assuming the microwave and toaster are not used simultaneously. You could not load an 8kw for proper break in. Did not see water heater or electric stove on the list.
 
I advise reading the operating manuals before you buy. Modern generators get by fine on the most nominal of loads. It's running for extended times with NO load that is potentially damaging. As is running for extended times at full load. Lot's of urban (or should I say dockside?) legend around this. Some of the preceding posts about futzing around with load management illustrate my point.
 
ben2go said:
Technomadia on youtube recently installed a 4.5K Northern Lights unit and it is mouse fart quite on thier 4788 BL.
Click to expand...

I have the 9Kw NL In the same boat and you can barely hear it run.

The watermaker high pressure pump makes more noise than the generator
 
guess I never thought of the aft cockpit lazarette as getting wet but . . . guess it's not as dry as the engine room in the salon. Thx.
 
Jmreim said:
guess I never thought of the aft cockpit lazarette as getting wet but . . . guess it's not as dry as the engine room in the salon. Thx.
Click to expand...

I'll caution you that mine can hardly be called a scientific sampling. If your lazarette stays bone dry in all weather and sea conditions, then have at it. Jamming it into an ER where it will have difficult access can have its own potential repercussions; you know the situation on your boat infinitely better than I do.
 
Another vote for Northern Lights. I have a 5kw, used it for 15 years, replacing an Onan. Quieter without a sound shield than the Onan with. Ditto the comment on larzarette gensets usually being a rusty mess.
 
Owned a NL 5KW
I purchased it from NY Generator
Originally I wanted the 6Kw however I was informed by NY Generator that the 5 and 6 were identical units. The parts lists on were identical. No use spending $$$ on the 6. This was 2008
 
This has been my experience as well. Two generators came with the boat. The 12.5kw, as was said, equals my 50amp shore supply and will run everything aboard including three air conditioning units. However, we use the 7.7kw Westerbeke most of the time. It will run one air conditioner and most oother loads with just a little attention to load management. If the boat is very hot after a day's run we'll use the larger generator to run the three A/C units awhile to cool down the boat more quickly and then switch to the Westerbeke if we still need power.
rslifkin said:
Sizing to run everything or not depends on the boat. For a lot of boats, that leads to installing a too-big genset. To equal my 2x 50A/125V shore power setup (which can run everything on the boat simultaneously) would require a 12kw genset. Realistically, I could run everything on a 10 or 11kw I think.

However, I've got a 6.5kw and never really wish it were bigger. It's not terribly uncommon for me to end up firing up an A/C unit just to keep enough load on it even if I don't otherwise need the A/C. It's enough to run all 3 A/C units and the water heater (with background loads like the battery charger). That's pretty much full load, but it's also fine to run the microwave if I turn one of the A/Cs off. The electric stove isn't an issue either with just a little bit of sane load management. I could make use of a bigger genset, but only occasionally. I'd rather have the smaller unit that's a little more efficient and easier to keep enough load on instead of having a bigger unit when I only want the extra 5 - 10% of the time.
Click to expand...
 
Another vote for Northern Lights. I have a 5kw, used it for 15 years, replacing an Onan. Quieter without a sound shield than the Onan with
Click to expand...

I'd invite comparison to the current Cummins Onan units.
 
When looking at noise, don't forget, there are 2 metrics that matter. Noise in the boat and noise outside the boat. My old gas powered Onan MCCK lacks a sound shield, so it's a bit noisy in the boat (but not terrible, especially concsidering I don't typically run it for more than a couple hours at a time).

However, it's almost silent outside the boat. If you're within a few feet of the hull you can hear it faintly. The exhaust is almost silent and discharges fairly close to the waterline so the water splash isn't particularly loud. This is also helped by running 2" exhaust instead of the required 1.5". The bigger pipes lead to the discharge from the water lift muffler splashing out far more gently instead of being violently (and loudly) shot out. The bilge blowers are louder from outside than the genset. Assuming blowers off, any boat anchored nearby that could possibly be bothered by the genset noise is anchored far too close for safety.

I've heard plenty of setups on other boats where the interior noise was better isolated, but they'd failed to muffle the exhaust well or make any reasonable attempt to control water splash noise, resulting in a genset that was somewhat obnoxious from the outside.
 
Good point. Outside our boat, the only sound heard is the swishing of the exhaust water.
rslifkin said:
When looking at noise, don't forget, there are 2 metrics that matter. Noise in the boat and noise outside the boat. My old gas powered Onan MCCK lacks a sound shield, so it's a bit noisy in the boat (but not terrible, especially concsidering I don't typically run it for more than a couple hours at a time).

However, it's almost silent outside the boat. If you're within a few feet of the hull you can hear it faintly. The exhaust is almost silent and discharges fairly close to the waterline so the water splash isn't particularly loud. This is also helped by running 2" exhaust instead of the required 1.5". The bigger pipes lead to the discharge from the water lift muffler splashing out far more gently instead of being violently (and loudly) shot out. The bilge blowers are louder from outside than the genset. Assuming blowers off, any boat anchored nearby that could possibly be bothered by the genset noise is anchored far too close for safety.

I've heard plenty of setups on other boats where the interior noise was better isolated, but they'd failed to muffle the exhaust well or make any reasonable attempt to control water splash noise, resulting in a genset that was somewhat obnoxious from the outside.
Click to expand...
 
Jmreim said:
guess I never thought of the aft cockpit lazarette as getting wet but . . . guess it's not as dry as the engine room in the salon. Thx.
Click to expand...


We had a genset in the lazarette on an earlier boat, and it was dry enough. And it did mean that the diesel noise back there wasn't an issue for the rest of the boat.

That area gets wet on our current boat, but it's mostly through our rod holders, which aren't (yet?) plumbed to a scupper. So even while wet, most of the rain water isn't landing where a genset would live, and could be better managed anyway (if I decided to do something about it).

The idea of factory sound shield is good. You would likely also want to be able to access all four sides of the unit for various periodic service. The doors (I think, lid, too) on ours all come off for access. Maybe most are made that way, but something to check.

The gensep idea sounds good, although we don't have one and I've not seen one. Often, the exhaust and water splash is what we hear most when other boats are nearby with their generator running.

-Chris
 
I just went through this on our 40' Mainship It had a 9kw Kohler that always had issues, was loud, and was heavy. Not beating up Kohler, it was a 20 year old unit.


I agree, if money was no object, I would go for the NL product. However, that's not my case. So I purchased a 4.5 kw Phasor unit, 1800 rpm 2 cylinder Kubota diesel, no sound shield. Installed with a new water lift muffler. Very satisfied with performance and quietness.



When we stop at an anchorage, I can run a 12k btu and a 9k btu a/c as well as the inverter recharging at ~ 125 amps, with no noticeable strain on the unit. If I need the stove top or hwh, I'll wait until the inverter charge rate drops <50 amps, or turn off one of the a/c's just to be safe.


We are just finishing a 6 week cruise in South Florida, running the a/c every night at anchor, something I refused to do with the old Kohler, just because of the noise. We spent 3 nights at one anchorage and ran the genset the whole time. Fuel gauge didn't move so it must be relatively economical. Did I mention quiet?


Dan
Passport
Palm City, FL
 
Second vote for a NextGen with sound shield. Mine is a 3.5K, but if I had the space I'd get the 5KW. They use Kubota diesels and run at 3600 RPM. Nice and quiet. Mine weighs 160 pounds, something to think about when placing it at the far end of the boat.
 
Just wanted to add that when Finally found a used nl5kw, which I watched for about two years and snapped it up when I saw it listed, took it home for the winter stripped all the bolt ons and started with fresh rebuilds, valve adjust, etc...

Anyhoo, The main point is that I hauled the boat in the spring and added underwater exhaust in addition to a water lift muffler. Last year at the park dock I was running next to the ramp and had two different people stop and ask if I was really running my generator. That made me smile. If you are next to the lazarette vents, you can hear a low hum, less than normal talking volume and not unpleasant.

Whatever you put in, I’d recommend a good muffler, underwater exhaust, some sound deadening material in the space it’s in and don’t skimp on the mounts. It’s really everything working in concert. At this point, I could make mine quieter still by constructing a long dorade behind my vents to attenuate the last bit of noise.
 
rgano said:
Second vote for a NextGen with sound shield. Mine is a 3.5K, but if I had the space I'd get the 5KW. They use Kubota diesels and run at 3600 RPM. Nice and quiet. Mine weighs 160 pounds, something to think about when placing it at the far end of the boat.
Click to expand...

SORRY IF THIS POST COMES UP MORE THEN ONCE HAD ISSUES POSTING


If I may, the NEXT GEN 3.5 KW is not a 3600 rpm generator , it is called a mid speed Gen, the Kabota single runs at 2600 or 2800 rpm (crs) , the engine drives the alternator though a very tight special belt , the pulley sizes on motor and alternator make the brush-less alternator spin at 3600 rpm! the motor is a thing of beauty the roller bearings on the crank shaft are huge and the crank drives two counter rotating balance shafts to smooth out the single cylinder motor.
I have one on my 26 foot custom LRC, it has the sound shield and extremely quite and produces no noticeable vibration at all, and tough to beat the price and the company is a pleasure to deal with!
 
Last edited:
If I may, the NEXT GEN 3.5 KW is not a 3600 rpm generator , it is called a mid speed Gen, the Kabota single runs at 2600 or 2800 rpm (crs) , the engine drives the alternator though a very tight special belt , the pulley sizes on motor and alternator make the brush-less alternator spin at 3600 rpm! the motor is a thing of beauty the roller bearings on the crank shaft are huge and the crank drives two counter rotating balance shafts to smooth out the single cylinder motor.
I have one on my 26 foot custom LRC, it has the sound shield and extremely quite and produces no noticeable vibration at all, and tough to beat the price and the company is a pleasure to deal with!
 
nexgen 3.5

Jmreim said:
Looking for advice on a very quiet genset for a 34' Mariner Orient Europa trawler. Not really sure how much power I need - just running a single AC unit, fridge/freezer and small appliances (toaster, microwave, coffee maker). The boat already has an 1800 watt inverter. Plan to install a diesel powered genset in the lazarette under the aft cockpit to keep it quieter in the salon and far from the master berth up front. Any suggestions for something really quiet would be appreciated. Thx!
Click to expand...


If a 30 amp shore power line does the job I recommend the 3.5 Nex Gen, it has great load starting performance as it has a 5KW alternator but only has enough HP to produce 30 continuous amps, no brushes so no alternator maintenance, extremely smooth as it has a counter rotating set of balance shafts in the Kabota diesel,all service is done from one side of unit and its a low flat profile which may or may not work for you, it runs at 2600 rpm if I remember ?. I have one on my 26 foot LRC, perfect unit for me, a fraction of the cost of NL units and weigh much less , I have the factory sound enclosure, great option. 1/2 load fuel burn is .2 GPH that's my AC for 5 hours on one gallon of stinky stuff!
 
hardchines said:
If I may, the NEXT GEN 3.5 KW is not a 3600 rpm generator , it is called a mid speed Gen, the Kabota single runs at 2600 or 2800 rpm (crs) , the engine drives the alternator though a very tight special belt , the pulley sizes on motor and alternator make the brush-less alternator spin at 3600 rpm! the motor is a thing of beauty the roller bearings on the crank shaft are huge and the crank drives two counter rotating balance shafts to smooth out the single cylinder motor.
I have one on my 26 foot custom LRC, it has the sound shield and extremely quite and produces no noticeable vibration at all, and tough to beat the price and the company is a pleasure to deal with!
Click to expand...

Thanks for the further explanation about where the 3600 RPM is on the 3.5.
 
Check out Fisher Panda, they are way quieter as have a closed liquid cooling system for the generation part (most are air cool) which means the entire unit is not just in a sound sheild but it runs MUCH Quiete and Cooler as you do not need engine air to cool the generator side ...we upgraded an 12kw onan to a fisher panda 15kw (they mainly make smaller units by the way) it is super quite, plus we added a gensep that futher quites the exhaust side by discharging the water below the water line so only exhaust leaves right above water line. Honestly our is so quite we forget it is on at times...now if only my water maker was quieter.

Feel free to PM for more, I am owner and have first hand great experience with this product that so many do not know about or share false info on it.
 
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