Loud Generator

[bikeandboat]

As we are solving one problem after another on our newly purchased older boat so that it is ready for a cruise, we sometimes run out of ideas for solving a problem. Our diesel generator falls into that category. The generator is the Westerbeke 4.4 KW diesel which used a two cylinder Mitsubishi engine. It is loud. We are looking for ways to quieten the monster.

A couple friends have tried the full jacket. They are quieter, but both have since had problems with the engines running hot. Not sure why, but with a two for two record, I am staying away.

Therefore, we are wondering about sound absorbing materials. Has anyone tried this method?

 

[sunchaser]

A couple friends have tried the full jacket. They are quieter, but both have since had problems how could this happen since water is the cooling medium, not air circulation with the engines running hot. Not sure why, but with a two for two record, I am staying away. Therefore, we are wondering about sound absorbing materials. Has anyone tried this method?

Westerbeke has made and sold sound enclosures for a very long time. Go to their website for a look see. To quiet the exhaust look up Centek water lift mufflers - very commonly used on gensets. Another trick is to use soft mounts, these are on the WB site as well.

I use all three of these "run quiet techniques" on my 12.5 WB and it is VERY quiet with little vibration

 

[GFC]

When I bought my boat the owner of the yard that was putting it back together after it got shipped from MI to OR suggested I add a "generator exhaust water separator". I didn't know what it was or what it did so he gave me the "idiot's guide" commentary.

Basically it separates the water from the exhaust and shoots it out below the boat. All that comes out the back is the air from the exhaust. When you're standing at the aft stbd corner of the boat you can hardly hear it run it's so quiet. No burbling, no gurgling sounds, just a quiet hum that's barely perceptible.

Since I only heard the gen run during the sea trials I couldn't really remember what it sounded like before he added the water separator, but it sure is quiet now. It's a 15kw Westerbeke.

 

[bikeandboat]

Thanks for the suggestions. To address the exhaust, it is not a problem. I am using a vernalift (Centrek) muffler. The exhaust if not loud. This boat has the generator under the salon sole, which is common on this size vessel. It is very loud in the salon. Our previoius boat was a 1970 Hatteras 53 with the original 15KW Onan generator. This one was under the galley sole. The noise level was much lower in the galley with the 15KW than it is in the salon of the Mainship 34 with the 4.4 KW.

I understand the water cooled question and that is why I said I did not understand the reason for the overheating with the jackets. I would guess than even a water cooled unit would give off some heat to the atmospere, or anyway it seems to get warm in the engine compartment with the generator running on any boat I have been on with a water cooled generator.

Just wondering if sound absorbing material would make a difference. It sounds like it would help, but I would like to see if anyone else has tried it before I take on such a project.

 

[psneeld]

My 8KW Westerbeke is just a whisper below the main salon floor with it's enclosure....
The engine which is easily talked over all but drowns out the genset...and stadalone the TV is easily heard and sleeping you hear but just a windlike noise...certainly no louder.

 

[2DASEA]

Come aboard my boat and listen to the soothing sound of Jimmy 2-53.you will return to your boat and you will barely notice the whispering Westerbeke !

 

[Daddyo]

2DASEA,
You have to post some pictures of your ship! She looks awesome, you and Delfin with your North Sea look

 

[2DASEA]

don't want to hijack the thread, just a couple of shots of my money pit

 

[bikeandboat]

Come aboard my boat and listen to the soothing sound of Jimmy 2-53.you will return to your boat and you will barely notice the whispering Westerbeke !

Actually, I did just that a number of years ago. 2-71 generator I believe. The loudest one piece of pleasure boat equipment I have ever heard.

 

[2DASEA]

Actually, I did just that a number of years ago. 2-71 generator I believe. The loudest one piece of pleasure boat equipment I have ever heard.

They don't call'm Screamin Jimmies for nothing!

 

[2DASEA]

Sound Shield?
We don't need no stinkin sound shield!

 

[amapola]

We have a 4.4 Westerbeke and yes it's loud. I'm sure the noise comes from the air intake which doesn't have a silencer. Actually, it's just a hole in the head under the exhaust manifold and behind the solenoid. I've been thinking about fitting a pipe to this hole and installing a silencer.

I've got a question for you. Does your generator jump all around and shake while it's running? Mine does and I don't know if this is normal for this engine or it's a problem with my engine.

 

[Baker]

I had an Onan 4kw on my Prairie. It was fairly loud. There is a local guy around here that makes sound enclosures for the chemical plants. He made a custom one for me. It velcroed together and he left Velcro panels at all of the service points. It was a very good job and cost a whopping $500! So yes, there are ways to make a sound deadening enclosure. I suggest you mine the services that may not be marine related.

 

[Tom.B]

What material did he use, John?

 

[Baker]

What material did he use, John?

I am not sure. The panels were 3-4 inches thick. They were vinyl covering some sort of insulation. It was heavy stuff. Very cleanly done. I wish I could provide more info. I may have some pics on my home computer but I doubt they would reveal anything.

 

[LarryM]

John,

Do you remember who did the work, or have a way to contact him? Boomarang still roars in the pilothouse.

Larry

 

[CaptTom]

My Onan 7.5 is a real "tooth rattler". It's bolted to a piece of plywood that's screwed to the stringers. I'm convinced it would be much better if I had something in between to dampen the vibration. If I could reach all the screws without removing the genset, I'd like to just lift up the plywood and slide in a piece of rigid foam or something.

The water lift muffler makes the exhaust almost silent, a guy 50' behind me at a mooring once didn't even know I'd had it running when I talked to him later.

I would also like to learn more about the insulating blanket covering.

 

[swampu]

Has anyone tried spray foam? I was going to spray the ceiling above the gensets and the engine when I get to that point. 2Dasea. That is a mean looking rig you got there. I like it.

 

[IslandEagle]

I have never used them, but these guys look likethey do exactly what you want:
Custom generator covers | Great Southern Insulation

Scott Welch
Island Eagle

 

[Tom.B]

Hey! Now THAT'S pretty slick there Scott. Might be what I would want too.

 

[Baker]

John,

Do you remember who did the work, or have a way to contact him? Boomarang still roars in the pilothouse.

Larry

I think I can dig him up. I'll let you know!

 

[Baker]

I have never used them, but these guys look likethey do exactly what you want:
Custom generator covers | Great Southern Insulation

Scott Welch
Island Eagle

Scott, that looks exactly like the material I had on mine.

 

[bikeandboat]

We have a 4.4 Westerbeke and yes it's loud. I'm sure the noise comes from the air intake which doesn't have a silencer. Actually, it's just a hole in the head under the exhaust manifold and behind the solenoid. I've been thinking about fitting a pipe to this hole and installing a silencer.

I've got a question for you. Does your generator jump all around and shake while it's running? Mine does and I don't know if this is normal for this engine or it's a problem with my engine.

Yes, my 4.4 KW Westerbeke is loud, but it actually runs smooth, especially for a two cylinder diesell engine. You may need a mechanic to take a look at your fuel system.

 

[BruceK]

My Onan 7.5 is a real "tooth rattler". It's bolted to a piece of plywood that's screwed to the stringers. I'm convinced it would be much better if I had something in between to dampen the vibration. If I could reach all the screws without removing the genset, I'd like to just lift up the plywood and slide in a piece of rigid foam or something.

I suspect foam type sheet would be soon destroyed. Surely you need flexible engine mounts.
There is certain to be an Onan noise reduction cover to suit. Or make one, ensuring it is easily removed for servicing. Mind you,the front one is easy to remove, but top and side covers(rarely removed) are a PITA.

 

[Edelweiss]

I will second that!!

I have an Onan MDJE 7.5 with Onan sound shield which is very quiet when buttoned up. Outside of the cabin you hear only the running exhaust water from the Aqualift muffler, which empties at the water line so no splash. Take one of the sound shield panels off though and you definitely know it's there.

I think the sound shield would make a big difference and if installed on shock absorbing motor mounts you will be much happier.

Larry B.

 

[healhustler]

I've got a 4.5KW Northern Lights/ 3 cylinder Lugger crammed under my galley. There's no space for a sound shield. The unit runs smooth enough but neither the Admiral or I care for the sound level in the stateroom, so I've cut a new hatch in the veranda and am about to swap the genset to that position. I'll have the opportunity to manufacturer my own mounts and there should be space for a sound shield, although I'll likely try it without it first. First photo is me working on the unit as mounted below the galley, 2nd photo is of the completed hatch cut and lid before doing the teak work.

 

[FF]

I did just that a number of years ago. 2-71 generator I believe. The loudest one piece of pleasure boat equipment I have ever heard.

You havent been shipmate with an air cooled LISTER !!

 

[CaptTom]

I have an Onan MDJE 7.5 with Onan sound shield which is very quiet when buttoned up.

I have the same genset with the Onan sound shield. I suppose it's not particularly loud, it just rattles & shakes the whole boat!

Mine has rubber motor mounts, but they don't seem to do the trick. I'm seriously thinking about trying to lift the whole base up an inch or so and slide in some rigid foam board.

 

[IslandEagle]

You havent been shipmate with an air cooled LISTER !!

Best generator in the world. I grew up in a place with no power, we ran two 4KW Lister ST-1s, then I had an ST-2. A buddy of mine had an HR-6 with over 60,000 hours.

Scott Welch
Island Eagle

 

[Edelweiss]

I have the same genset with the Onan sound shield. I suppose it's not particularly loud, it just rattles & shakes the whole boat!
QUOTE]
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Sounds like you are feeling it, more than hearing it. That is a thirty plus year old generator and those motormounts may need replacing. The vibration is telegraphed into the boat through the stringers.

It is a diesel and you are going to feel vibration, but you may be able to eliminate some of the harmonic vibration by isolating the mounting plate from the stringers. But I have never felt the need to try it. Let me know how that works for you if you do?

Larry B