Quiet Genset

[rgano]

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!

I have found that the 3.5 has its limits in the 90-degree water we experience here in the summers. Above about 22 Amps it overheats above its 225 set point and shuts down (using IR thermometer on the heat exchanger's side). There is no circulating pump for the coolant meaning it is naturally circulating, and Nextgen tells me it is thermally stable at around 210 degrees F. When mine first overheated earlier this summer running my 10 KBtu and 13.5 KBtu air conditioners simultaneously, I called NextGen. The temperature while running just the 13.5 KBtu AC was around 218 degrees with no thermal shutdown. NG suggested running Barnacle Buster through the seawater circuit as some of their south FL customers did three times a year to keep theirs cool - mind you this generator was brand new out of the box August 2018 with only 70 hours when the incident occurred and is always run of freshwater after every run. That brought the running temp from 218 down to around 200 for the 13.5 KBtu AC, but it would still overheat when adding in the 10 KBtu AC. Don't get me wrong, I like this unit, but I think a 5 KW NextGen with a probably larger cooling capacity not running so close to its limits would handle this heat issue better. I was able to easily run both AC units on the generator in the fall and spring with cooler waters under the boat.

 

[ghost]

Interesting. I have the identical Kubota single cylinder with a 200 ish amp alternator I put together from parts sitting next to my northern lights. I was originally going to put the underwater exhaust on the Kubota, but that was before I got the NL. It now sits just outside the NL. With just a water lift muffler, I found it to be surprisingly loud and it’s not as smooth. It was not in a sound shield but I invested in sound material on the walls and ceiling of the lazarette, which makes the NL with sound shield just that much quieter. I don’t run the dc generator much anymore, but for quick battery charging, it will put out more amps than the NL powering my 120 amp battery charger.

Mostly, I just did not like the sound of the single cylinder exhaust. I would definitely invest in underwater exhaust for that one. I had a sailboater gal walk up the dock pinching her nose (stinkpot) because she did not like the sound of the Kubota and she thought it represented everything bad about powerboats. I don’t like dealing with them anymore, their minds are fixed, so I rarely run it.

 

[hardchines]

I have found that the 3.5 has its limits in the 90-degree water we experience here in the summers. Above about 22 Amps it overheats above its 225 set point and shuts down (using IR thermometer on the heat exchanger's side). There is no circulating pump for the coolant meaning it is naturally circulating, and Nextgen tells me it is thermally stable at around 210 degrees F. When mine first overheated earlier this summer running my 10 KBtu and 13.5 KBtu air conditioners simultaneously, I called NextGen. The temperature while running just the 13.5 KBtu AC was around 218 degrees with no thermal shutdown. NG suggested running Barnacle Buster through the seawater circuit as some of their south FL customers did three times a year to keep theirs cool - mind you this generator was brand new out of the box August 2018 with only 70 hours when the incident occurred and is always run of freshwater after every run. That brought the running temp from 218 down to around 200 for the 13.5 KBtu AC, but it would still overheat when adding in the 10 KBtu AC. Don't get me wrong, I like this unit, but I think a 5 KW NextGen with a probably larger cooling capacity not running so close to its limits would handle this heat issue better. I was able to easily run both AC units on the generator in the fall and spring with cooler waters under the boat.

I think you are correct, I have only run my unit in the relatively cool waters of the North East, I think I would make sure of the water flow just to make sure , if you have not already done it, a new impeller is a cheap test, or just fix it the correct way, move north!! Well one other thing is to make sure your cooling anti freeze is not too rich, straight water conducts heat better then a antifreeze mix but will boil if it gets hot enough! good luck, now I will have to worry about going south next year and having my AC on.

 

[Delfin]

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

Yup, what he said.

 

[rgano]

I think you are correct, I have only run my unit in the relatively cool waters of the North East, I think I would make sure of the water flow just to make sure , if you have not already done it, a new impeller is a cheap test, or just fix it the correct way, move north!! Well one other thing is to make sure your cooling anti freeze is not too rich, straight water conducts heat better then a antifreeze mix but will boil if it gets hot enough! good luck, now I will have to worry about going south next year and having my AC on.

Yup, in cool waters here it does OK. Water flow including new impeller was the first troubleshooting effort. Oil was changed and antifreeze from factory was emptied before ever starting it the first time when it was new and a 50-50 mix of Shell ELC ensured cuz I don't trust anybody. If you are running a single ac of 13.5 KBtu, you will be OK, just don't try to run other stuff. I have reduced the heating element in the water heater from 1400 to 1000 Watts so I can run it with one AC (do NOT want it connected to the main engine cooling circuit).

 

[Simi 60]

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.

Even better is a 3 pot @ 1500rpm
Ours used to be an 1800 but the PO changed the generator head and dropped the rpm.

 

[Keysdisease]

What Ghost said. Engine makes 3 kinds of noise, airborne, structure borne and exhaust. Address each and you can have a quiet genset'
Insulation, gen-sep (u/w exhaust) and secondary mounts = quiet

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.

 

[hardchines]

antifreeze ??

Yup, in cool waters here it does OK. Water flow including new impeller was the first troubleshooting effort. Oil was changed and antifreeze from factory was emptied before ever starting it the first time when it was new and a 50-50 mix of Shell ELC ensured cuz I don't trust anybody. If you are running a single ac of 13.5 KBtu, you will be OK, just don't try to run other stuff. I have reduced the heating element in the water heater from 1400 to 1000 Watts so I can run it with one AC (do NOT want it connected to the main engine cooling circuit).

Sounds like you did your homework, I see you changed your antifreeze from the factory juice, I remember talking to Next gen about the anti freeze, I also remember them saying the ratio was very important but I do not remember what mix he called for, did you mention to them that you changed it ? or did the tell you what the ratio should be, just a thought! Well I just called next gen, and as I suspected the ratio should NOT be 50/50, it comes from the factory and calls for 30/70, 70% water, this makes a big difference as water conducts heat much better the antifreeze, hope this helps. If you call them (ken) or Scott you call here it in person, 904-642-8555 Best of luck

 

[hardchines]

wrong antifreeze I think

Sounds like you did your homework, I see you changed your antifreeze from the factory juice, I remember talking to Next gen about the anti freeze, I also remember them saying the ratio was very important but I do not remember what mix he called for, did you mention to them that you changed it ? or did the tell you what the ratio should be, just a thought! Well I just called next gen, and as I suspected the ratio should NOT be 50/50, it comes from the factory and calls for 30/70, 70% water, this makes a big difference as water conducts heat much better the antifreeze, hope this helps. If you call them (ken) or Scott you call here it in person, 904-642-8555 Best of luck

I also noticed you put in Shell elt antifreeze, I tried to find out what it is made of, found lots of bla bla bla and its the best best but not a fact to be found! I believe that nextgen calls for ethylene glycol, and at the ratio I mentioned in previous note, 30/70 that's 70% water, NOT 50/50! Some of our best intentions and improvements we try to do sometimes bite us in the butt. The good news is you probably have NO generator problem! I would do a drain and a clear water flush, make a mix of 30/70 with ethylene glycol and clean water (distilled if you have it), cheap and no minerals being added to your system. Make sure your sound enclosure has a good exhaust blower that is sucking out all that hot air. The more flow the more better!

 

[rgano]

I also noticed you put in Shell elt antifreeze, I tried to find out what it is made of, found lots of bla bla bla and its the best best but not a fact to be found! I believe that nextgen calls for ethylene glycol, and at the ratio I mentioned in previous note, 30/70 that's 70% water, NOT 50/50! Some of our best intentions and improvements we try to do sometimes bite us in the butt. The good news is you probably have NO generator problem! I would do a drain and a clear water flush, make a mix of 30/70 with ethylene glycol and clean water (distilled if you have it), cheap and no minerals being added to your system. Make sure your sound enclosure has a good exhaust blower that is sucking out all that hot air. The more flow the more better!

I posted a long story about that electric end blower. Damned thing (Jabsco POS) burned up its crappy motor and seized causing a short which because there is was NO fuse in the installation, burned up the entire wiring harness on my original 3.5. Smoke all over the place. The replacement harness from NG had a fuse integrated. Hmmmm. The replacement NG 3.5 also had a fuse. However, since the whole generator needs to be pulled to replace the stupid blower and because I did not want to have to run the battery charger to keep the fan going (fuel pump is a tiny draw), I elected to put an AC brushless blower back there connected to the generator via a 30 second time delay to ensure the voltage to it is stabilized. NG was ok with this.

They were OK with the anti-freeze, but I am going to do some more research. Thanks.

 

[hardchines]

I agree the dam jabsco blowers suck, I lost mine 2 years ago in the trent severn waterway in Canada, was able to buy a home dryer hose at a lock near a town and connected it to my bilge blower, NG said I needed a blower hooked up and I believed them. unit is older and now that you mention the fuse I will install one, another to do item , line 39 of my list, I am planning on a 120 volt blower also!

 

[rgano]

I selected a Vents VK100 and installed a push-button 10 Amp breaker on the genny. This fan has about the same CFM rating as the Jabsco.

 

[koliver]

Don't expect the answers here to be definitive.
I had to replace my 5kw Onan, 3 cyl Kubota in an Onan shield.
The mechanic helping me with this project recommended and I went with the Westerbeke 4.5 in a Westerbeke sound shield. Theory was their reputation was for the best sound shield, so quietest result. Again a 3 cyl drive engine. Connected to the original exhaust system so no change there.
The old Onan was quieter than my original Norcold fridge. Once I got rid of that gem, I could hear the genset when running. Otherwise, we had gone to bed forgetting that it was on. The Westerbeke, supposed to be quieter, would never lull one to sleep, though it is quiet enough that some folks have not noticed it running.
I think the secret to quiet running lies with the sound shield, not the engine.
The Westerbeke shield has little protection under the engine.
The Onan had a compete, unbroken tray under.
If I spent some effort, I might quiet that area and achieve total silence.