Sound Box on NL gen-set?

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PMF1984

Guru
Joined
Sep 10, 2016
Messages
637
Location
United States
Vessel Name
Wanderer
Vessel Make
Pilgrim 40
So I have a Northern Lights generator down below, not in the engine room, but sort of a hold forward of the ER. Normally, the house battery bank will stay up with the solar panels and the alternator while underway.

Last Spring I was laid in at a dock on the Dismal Swamp for 3 days because of a bad blow associated with 3 days of rain.

So I ran the generator which worked fine.

But wow, it was loud.

I noticed there are some noise enclosures available for this problem, so I have a couple questions.

1. Do these things work?
2. Is it worth it to buy or should I try some sort of self fabrication?
3. Would it cause an overheating issue?

Suggestions welcome

John
 
I have a sound shield and put in underwater exhaust. Now you can barely hear it. Sounds like maybe a small pump is running. Huge difference.
 
My NL 6KW has a sound enclosure and the standard lift exhaust. Even at the dock, I cannot hear but a hummmm.
I would encourage you to find a enclosure designed for your generator.
 
NL 9KW genny with sound box. Works well; minor hum is all I hear. It works well.
 
While I’d recommend against a homemade solution, be aware the Northern Lights enclosure is a little involved. The base gets bolted to the boat, the generator then sits on top of that and bolted to the base, then the sides and top are attached. The fuel hoses pass through the base via thru-bulkhead type fittings so there’s a bit of a project involved. But yes, if your gen isn’t in an insulated ER, you probably want one.
 
Porgy said:
While I’d recommend against a homemade solution, be aware the Northern Lights enclosure is a little involved. The base gets bolted to the boat, the generator then sits on top of that and bolted to the base, then the sides and top are attached. The fuel hoses pass through the base via thru-bulkhead type fittings so there’s a bit of a project involved. But yes, if your gen isn’t in an insulated ER, you probably want one.
Click to expand...
I removed the factory sound enclosure from our NL generator for maintenance and never put it back on. The rubber mounts and base are still in place as Porgy described. I think the mounting system is a major factor in keeping things relatively quite without the balance of the enclosure. I wish I had measured the db level before I removed the enclosure. I noticed a little increase in the noise level but nothing drastic. If we wish to decrease the noise level in the future I will add to the engine room sound deadening. A covered generator is out of site and therefore out of mind when it comes to maintenance. I like to be able to easily give it a visual looking for little things before they become major issues.
 
A well engineered sound shield really works. My boat came to me with an Onan 4kw generator in a purpose built sound shield by Onan. It was so quiet that we would forget to shut it off when going to bed. The fridge was louder.
The downside of that design was that when there was a water leak from the heat exchanger, inside the sound shield, it retained the water inside the shield, and the air movement caused the windings to get covered in salty spray, and failed.
The replacement Westerbeke came with a Westerbeke designed sound shield. It is pretty quiet, but not so much as the Onan, but it has no floor, so no possibility of a similar failure.
Still far less noise than if the side is left open.
 
Just had a NL 6kw installed with sound shield. It is extremely quiet w/ the shield. It is also quiet w/o the shield but not as much. Of course this is in comparison to our old Onan MJDE 7.5 aka Mr. Shaky. The mounting of the generator to whatever supports it is extremely important in reducing noise.

Tator
 
The other 2 items that reduce noise, mentioned already: underwater exhaust (actually gas/water separator) and what's called "secondary isolation," that is lift the entire genset and add 4 additional isolators under the entire unit.

There is also a company in Ft Lauderdale that makes a very nice "soft shield," not cheap not when compared to a factory hard enclosure could be an option.

Custom generator covers | Great Southern Insulation

:socool:
 
I have a 5kW NL in my engine room, no sound box. Very quiet in the boat.

I'm not a fan of sound boxes, they inhibit maintenance and inspection enough to be an issue.

If there are sound issues, there may be something else going on. Without addressing that, the soundbox may help, but not as much as one may think.

A bugger on these is intake noise, and this can be addressed in a variety of ways.

What NL machine?
 
We have a 9KW NL on Blue Sky in an NL sound enclosure in the lazarette. Don't hear it at all, except for the exhaust noise (no underwater exhausting).
It is noisier with the easily removed front panel off for sure, but normal maintenance/monitoring is easily done with it off. And they all come off for more serious stuff.
 
Ski,

I have a M643.Standing outside above the exhaust, it's very quiet. Just very bothersome aboard.

Looks like the dealer's part for sound proofing for M643 is not available. 39-78303.

I tried getting a diagram from boatdiesel.com but couldn't get the image to pop up.

John
 
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PMF1984 said:
Ski,
I have a M643.Standing outside above the exhaust, it's very quiet. Just very bothersome aboard.
Looks like the dealer's part for sound proofing for M643 is not available. 39-78303.
I tried getting a diagram from boatdiesel.com but couldn't get the image to pop up.
John
Click to expand...

John perhaps there is a Pilgrim group and you can get dimensions from one of them?
 
Last edited:
Ski in NC said:
A bugger on these is intake noise, and this can be addressed in a variety of ways.
Click to expand...

Not on Turbo generators. I remember this one CAT 4.4 that used a Perkins block that in the Natural version would shake the entire boat with intake stroke noise. Very low frequency and extremely annoying

:socool:
 
Thanks Old Dan,

I found those links . The boat diesel one I can’t get past the thumbnail to the actual plan in either Chrome or Safari.

The installation instructions gave me a headache and gave me a severe ADHD reaction, so I streamed a movie. And I thought, without researching it, I could buy a couple Efoys instead. Then I started thinking I could just get some earplugs.

Someone makes a “soft” cover, drawback review is that it is “heavy.” Maybe easier to install though.

The NL one really looks like it’s best install at the original install.

John
 
PMF1984 said:
Thanks Old Dan,

I found those links . The boat diesel one I can’t get past the thumbnail to the actual plan in either Chrome or Safari.

The installation instructions gave me a headache and gave me a severe ADHD reaction, so I streamed a movie. And I thought, without researching it, I could buy a couple Efoys instead. Then I started thinking I could just get some earplugs.

Someone makes a “soft” cover, drawback review is that it is “heavy.” Maybe easier to install though.

The NL one really looks like it’s best install at the original install.

John
Click to expand...

John, the 3rd URL on the 3rd page, picture of sound box, dimensions listed under the pic.

Per the ease of putting it back on? LOL Not so on my 20KW
With the proper sound box, business side of the generator, simple to remove and replace panel. Presto, easy pleasey
 
So the sound shield depicted on the M643 propaganda sheet is no longer available.

There is a good picture of this sound shield in the M673 parts book. I read somewhere that the new design for the M673 fits the 643, part 05-78000.

I asked Diesel Parts Direct for a quote, nobody has a posted price on this.

Also asked GSi for a ballpark quote on a soft cover. Looking at photos the frame for these look pretty easy to fabricate.
 
I looked for a sound shield a couple months ago and NL had none and only offered them on new sales. Mine is in the lazarette so my approach now is to isolate the mounting base from the stringers and put some sound shielding on the lazarette hatch just above the genset.
 
Find a company that makes traveling cases for bands. They will build what you want.
Two points to consider
1. the interior foam is not going to support combustion.
2. Get the vent hole and fan placed according to the proper planes.
 
My Gen is under the cabin sole. Thick carpet dropped 10db . I now cruise with all machinery @ 68 Db.
 
The air intake on the NL 643 has almost no intake silencing. I modified my rocker cover/intake manifold so a remote filter silencer could be used. I figure the noise level was dropped by half.

There is an industrial version of the Shibaura 643 that comes with an intake already ducted for a remote filter (think lawn tractors, industrial generators), that could be swapped out and remote filter/silencer used. Will require some space above the unit to accommodate the plumbing. I just chose to make it myself out of the original.
 
koliver said:
A well engineered sound shield really works. My boat came to me with an Onan 4kw generator in a purpose built sound shield by Onan. It was so quiet that we would forget to shut it off when going to bed. The fridge was louder.
The downside of that design was that when there was a water leak from the heat exchanger, inside the sound shield, it retained the water inside the shield, and the air movement caused the windings to get covered in salty spray, and failed.
The replacement Westerbeke came with a Westerbeke designed sound shield. It is pretty quiet, but not so much as the Onan, but it has no floor, so no possibility of a similar failure.
Still far less noise than if the side is left open.
Click to expand...

Keith
Did your Onan base have drain holes so a raw water or coolant leak would show up quickly? Our Westerbeke has drains and cannot "flood" the area inside the enclosure as fortunately evidenced by a failed raw water pump some years ago.
 
My Onan suffered a leaking water pump seal and heat exchanger seal under the previous owner. This necessitated a cleaning and repainting of the pan (why don't the leaks occur in freshwater?). I added 2 pan drains during the remediation process.

Ted
 
Ski,

IMG_0464.jpg

Is this what you meant for the Shibura unit? It uses a different rocker cover, which at this point in time, I doubt is available.

Maybe expand a little on your solution, as I lack the imagination to visualize it.
 
PMF1984 said:
Ski,

View attachment 111660

Is this what you meant for the Shibura unit? It uses a different rocker cover, which at this point in time, I doubt is available.

Maybe expand a little on your solution, as I lack the imagination to visualize it.
Click to expand...

There's one on Ebay for 40 bucks. Can use a Donaldson filter/silencer from something like a Bobcat or tractor.

https://www.ebay.com/itm/Ford-LGT14...R-HEAD-VALVE-COVER-SBA111216610-/324193319035

This one looks a lot cleaner:

https://www.ebay.com/itm/FORD-96072...-14hp-Diesel-Engine-Valve-Cover-/193466776827
 
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