What can be done to quiet a Kohler generator?

I'm curious if the volume of the gensets is louder than the blower. I never operate my Kohler 5w without the blowers on and I don't have a shield. By far, the blowers drown out the gen. Am I lucky or is this consistent with other owners?

Peter
 
These are my measured figures. Figures measured at centre of table with calibrated Sound Level meter.

Gen Only (With Air Condition + fridges as load) : 63 dBa
Blowers Only: 62.5 dBa
Gen + Blowers (With Air Condition + fridges as Load) 66.2 dBa

So combined noise level is actually about 3 dBa higher than either by themselves.

I have new blowers waiting to be installed plus I will put a sound shield on. I'll update the figures once that is done.
 
Thats very helpful info. The benefit for installing the shield is a reduction in noise of approx. 4 db. When one considers the cost, not to mention the difficulty installing the shield after market, it really makes no sense imo. I don'
t know what a genset weighs but I gotta believe it's a huge job to lift one out of the bilge in order to install the lower bottom tray. SeaRay really ought to install the lower tray as a standard item in our boats. If that had been done, shield install would be much easier and cost effective.
 
Keep in mind that for every 3 dBa increase, the sound level is doubled. So a sound shield at -4dB would cut the level by over half.

(correct me if I'm wrong kaz)
 
JimG said:
Keep in mind that for every 3 dBa increase, the sound level is doubled. So a sound shield at -4dB would cut the level by over half.

(correct me if I'm wrong kaz)
Click to expand...

Does that apply to sound levels or just antenna gain? At some point i guess its all waves.
 
kaz911 said:
I have new blowers waiting to be installed plus I will put a sound shield on. I'll update the figures once that is done.
Click to expand...

What type of blowers do you have now and what are you switching to? Curious as I want to replace my blowers to increase volume of air moving through the bilge. Never thought of the sound levels, but if you have something in mind that is much quieter, I'm all for it.

Tom
 
Continuous use "squirrel cage" type blowers are available and are much quieter than OEM plastic "in line" blowers. The downside is that they use more amps to run and I'm not sure if the existing wiring is sufficient for the additional current demands. Sounds like it's worth a new post to find out!
 
in pure sound pressure dB - 6 dB is a doubling (think of that as amplitude or volt). 3 dB doubling is "Power" (think of it as Ampere). Since I measure Sound Pressure (Amplitude/Volt) - 6 dB is equal to double up.

Old studies says 10dB is perceived as a doubling - but more recent studies says anywhere from 6dB to 10 dB is perceived at a level doubling.

But most people get annoyed at sound levels in the "open" of more then 45-47 dB. Inside the figure is about 40-42 dB. But it is also dependent on noise type. I "like" the sound of the genny better than the sound from the blowers. So my first focus is the blowers.

EDIT - the Jabsco blowers I have bought are the 35770 series. They are available in 12 or 24 volt versions and in flex or flange mount. I think it was Frank(Fwebster) who recommended them here? But my memory might fail me!
 
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Our boat's genny is very quiet and it is not due to just one thing like a shield (which we do not have.). First the WB is a quiet machine as others have noted. The blowers in the boat are very quiet as well. A fairly large water lift muffler reduces noise and the exhaust goes out the back of the boat just below the water line. Its sound is pleasant and not very noticeable from inside the boat or even outside, just a low hum. I believe the main sound reduction, however, is due to the insulation Tiara uses in the floor of the cockpit. There is a good 2-3" of sound deadening material that is sandwiched between the floor's top and bottom layers. This is all nicely finished and looks like finishes on the outside of the boat. Those of you with noise issues should evaluate the potential for fastening some sort of fire rated insulation material to the bottom of the cockpit floor. Better blowers are an easy fix as well.
 
kaz911 said:
These are my measured figures. Figures measured at centre of table with calibrated Sound Level meter.

Gen Only (With Air Condition + fridges as load) : 63 dBa
Blowers Only: 62.5 dBa
Gen + Blowers (With Air Condition + fridges as Load) 66.2 dBa

So combined noise level is actually about 3 dBa higher than either by themselves.

I have new blowers waiting to be installed plus I will put a sound shield on. I'll update the figures once that is done.
Click to expand...

Kaz,

Did you ever put the sound shield on your Kohler and if so what was the result? The Kohler generator in my boat 330 is disturbingly very loud. I need to do something to bring the noise level down.
 
JimT said:
Kaz,

Did you ever put the sound shield on your Kohler and if so what was the result? The Kohler generator in my boat 330 is disturbingly very loud. I need to do something to bring the noise level down.
Click to expand...

Jim, Do you have the dual stage muffler? I'd do that first.

MM
 
JimT said:
Kaz,

Did you ever put the sound shield on your Kohler and if so what was the result? The Kohler generator in my boat 330 is disturbingly very loud. I need to do something to bring the noise level down.
Click to expand...

Hi Jim,

no not yet. I'm looking for some really good base vibration dampening material to put underneath first. And it has been summer here - so temperatures to high to work in the engine room.

So if anyone have any recommendations - i'll be happy to listen. I would like to put it under the SoundShield and my A/C and the A/C pump. They are the worst noise makers (and maybe the Waterpump)
 
MonacoMike said:
Jim, Do you have the dual stage muffler? I'd do that first.

MM
Click to expand...

Mike,

No, I have the single stage Centek Varnalift. The exhaust discharge doesn't seem to be the major source of the noise. The unit itself is very loud. There is alot of empty space in my bilge and I think its amplifying the noise. Fortunately, there is plenty of clearance around the genny for a sound shield.
 
kaz911 said:
Hi Jim,

no not yet. I'm looking for some really good base vibration dampening material to put underneath first. And it has been summer here - so temperatures to high to work in the engine room.

So if anyone have any recommendations - i'll be happy to listen. I would like to put it under the SoundShield and my A/C and the A/C pump. They are the worst noise makers (and maybe the Waterpump)
Click to expand...

I measured the sound levels today and they are very close to what you report. Did you measure the level after installing the squirrel cage blowers?
 
JimT said:
I measured the sound levels today and they are very close to what you report. Did you measure the level after installing the squirrel cage blowers?
Click to expand...

Squirrel Cage blowers took blower noise down from 62.5dBa to 51.5 dBa - so an 11 dBa reduction - with ZERO reduction in airflow.
And took the loaded Generator+Blower down from 66.2 dBa to 63 dBa - so a 3 dBa reduction.

So now I'm just hanging in there for the sound shield fitting if I can find some good "base" material to mount it on. That should hopefully take another 6 dBa off at least (= 50%+ reduction). A lot of noise is also reflected out of the "air intakes" - and that could do with some noise reduction material on the walls there.
 
Thanks, Kaz. The squirrel cage blowers and a dual stage muffler are next on my to do list. I'm going to wait and hear on the sound shield. Do you have any photos of your blower install?
 
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