How noisy is your boat?

caltexflanc said:

Anyone here realize that noise levels double every 3db, thus lowering tolerance by half? Just a little fyi...

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Here's a chart I'd seen as to perception.

Perceptions of Increases in Decibel Level:

Imperceptible Change 1dB
Barely Perceptible Change 3dB
Clearly Noticeable Change 5dB
About Twice as Loud 10dB
About Four Times as Loud 20dB


I then found this explanation that explains your 3dB and what appeared a difference in charts, but is not.

Ratio doubling means:
− a power level of +3 dB, or a sound intensity level of +3 dB
− an electric voltage level of +6 dB, or a sound pressure level of +6 dB
− a loudness level of about +10 dB
−10 dB more SPL means 10 times increase in amplifier (electric) power.

So 3 dB doubles the sound intensity, even if it takes 10 dB to double the loudness with which we hear it.

Your point is certainly very valid that we might think of going from 70 to 77 at being minimal and only a 10% increase, but it's a huge increase.

I personally do not like yelling or being yelled to. I'm soft speaking and prefer to talk that way. I can be loud but reserve that for singing. The moment I feel like I must yell to converse on a boat is when I'm going to find a way to reduce the sound.

You want to reduce the sound? Move away! Sound follows the inverse square law.

Insequent said:

You want to reduce the sound? Move away! Sound follows the inverse square law.

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Wifey B: You'll just hear the sounds of splash followed by gurgle gurgle.

N4061 said:

Thanks for this post and insight into your positive experience with the Flemming 55 (great boat). While I'm not 100% positive I believe the soundproofing enhancement on the new Helmsman 38E models will use similar materials and construction process to achieve a superior level of comfort. I'm glade to hear you view point and excited to see the level of improvement on our boat compared to earlier models which I already thought very quiet boats.

John T.
Helmsman 38E - Under Construction

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It will be interesting to hear your real world POV after delivery. Was just on a Helmsman 38 and was a bit surprised the engine is directly under the PH (Guess I hadn't studied the deck layout well?). On the Fleming the engines are under the salon, and there are two huge fuel tanks between the engine room and the rest of the boat going forward. In the Fleming brochure they also tout the Aquadrive system as another means of quieting the boat.

I'm not saying the Helmsman will be louder, we all know about the tech advances in materials, plus the new engines being quieter, I'm just curious to know how it goes!

All the best.

caltexflanc said:

Anyone here realize that noise levels double every 3db, thus lowering tolerance by half? Just a little fyi...

Click to expand...

Somehow the entire dB scale is less than intuitive...
I studied math (years ago!) and it still seems foreign to me...
Bruce

caltexflanc said:

Anyone here realize that noise levels double every 3db, thus lowering tolerance by half? Just a little fyi...

Click to expand...

Kinda reminds me of the Richter Scale.

Not sure I would call it noise!

My ears are 20 foot off the water on the FB. I usually run the Lugger 174hp engines at 1800 (WOT is 2400, continuous duty is 2200). They are way below me in the well-insulated ER.

Any noise is from the exhaust. Since I usually have the Glendenning syncs on I would say it is more like a distant twin engine airplane sound rather than noise. We can certainly have a normal conversation on the FB or PH.

On the bridge... We love to listen to the mellow back and forth revolution gentle-hum of our engines while they are in near perfect syncro at just under hull speed!

The Cummins video, it sounds like they showed it at 3 different RPM's. What they were I don't know. Take a ride in a new 6.7 Dodge pu, and you will instantly notice the lower noise levels. Same holds true for the marine QSB.

She purrs like a kitten. Rrrrrrrrrr!


Jim
Sent from my iPad using Trawler Forum

Insequent said:

You want to reduce the sound? Move away! Sound follows the inverse square law.

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Interesting all this. I'd like to thank whoever posted re the dB measuring apps, because I downloaded one called 'dB Meter Pro', and am having a lot of fun with it. Interestingly, background noise in what one would call a quite quiet environment is still 35-40dB most times. That surprised me a bit. This inverse square law thing is a bit weird really...
Looking forward to testing inside our boat at cruise speed next time we go out.

We have about 5" of insulation in the engine room including perforated aluminum sheathing so the sound gets absorbed into the insulation. The insulation package is 2-3" of fire retardant spray foam then 1/2" plywood, 2" of rock wool insulation, then perforated aluminum sheathing. The plywood was installed on the walls only so I could screw fixtures to the walls anywhere I wanted.

In the wheel house with the doors and windows closed, we see between 50-55 decibel @ 1600 RPM. I'm dry exhaust, and have a flapper for a rain cap on the exhaust, and when idling, the flapper slapping will get the decibel spiking at 55. At idle, the exhaust flapper is sort of loud with it's steady metallic clap, but I kind of like it as it reminds me of my old tractor I no longer own.

The boat's extremely quiet.

I've not checked the roof with the dry exhaust outlet nor the cabin where the engine room door is and am curious as to what readings I'll see. At cruising RPM, when in the engine room, ear plugs probably should be worn.

While building the boat, we had chartered an older 42 Grand Banks in Florida for a week vacation. At cruising speed on that boat, it was almost unbearable being in the salon. The noise was bad, but almost as bad were the rattles and vibrations. The complaints from the wife asking if our boat was going to be this loud sent me down the path of how to knock down sound in a boat. The folks at Sound down gave me lots of insight as to what an engine room sound proofing system needs.

Conall

Conall63 said:

The complaints from the wife asking if our boat was going to be this loud sent me down the path of how to knock down sound in a boat. The folks at Sound down gave me lots of insight as to what an engine room sound proofing system needs.

Conall

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Hi Conall

Irrespective of boat sound (but, good going to keep wife happy!) I would love to see better photo of your boat in avatar. Looks real nice. I love the bow. Appears that baby does well for handling seas.

Art

Connal, thanks for the tip on Sound down.

Did you use any of their products in the engine room? Curious how that went, "sounds" good.

Their products look similar to stuff I've used by E.A.R. Their stuff was used to line sub hulls for US Navy. I learned enough to be dangerous with sound abatement from those guys.

OK, if you guys think logSPL app is cool, go google "spectrum analyzer for iPad".

A spectrum analyzer shows you what frequencies things are vibrating at and how "loud" they are. That means you don't have to guess on the noise source, you can tell if it's RPM related, prop speed related, or a fundamental of what ever the forcing function is.

Last time I used one of these it cost $28K and lived on a roll around cart! Now it's an app for a phone or tablet! These things have become the Star Trek Tricorder for boats, amazing.

Conall63 said:

In the wheel house with the doors and windows closed, we see between 50-55 decibel @ 1600 RPM. I'm dry exhaust, and have a flapper for a rain cap on the exhaust, and when idling, the flapper slapping will get the decibel spiking at 55. At idle, the exhaust flapper is sort of loud with it's steady metallic clap, but I kind of like it as it reminds me of my old tractor I no longer own.

The boat's extremely quiet.

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That is an understatement!

GoneFarrell said:

Last time I used one of these it cost $28K and lived on a roll around cart! Now it's an app for a phone or tablet! These things have become the Star Trek Tricorder for boats, amazing.

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Phone apps still amaze me. Seems like every day something new and it's free or $2.99 to do something that cost thousands before. Look back and old science fiction movies sometime. We watched one recently. What was science fiction in the movie had now been surpassed.

BandB said:

Phone apps still amaze me. Seems like every day something new and it's free or $2.99 to do something that cost thousands before. Look back and old science fiction movies sometime. We watched one recently. What was science fiction in the movie had now been surpassed.

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Teleportation is coming. First it will be small material objects. Eventually it will be larger objects. Then, it will be living things. And, then... it will become used for human beings. Talk about high tech!

In 50's / 60's Grumman Engineering silently performed underground studies on "anti-gravity". I learned in the late 60's; by having repeat conversations with a relatively close source to the project: Gravity and molecular "gluem" (that's what they called it back them) are kissing cousins. Once gravity consuming an object can be successfully and stably removed the molecules can be disassociated and transported via electric current to be re-associated. There were "things" lost during the experiments. From what I understood some of the findings sent shock waves throughout the participating scientists and engineers ranks. Top secret level commitment on this project did not allow the engineer to provide me with deep discussion on many of the facts that were uncovered. That project was suddenly closed down. I imagine that after those discoveries some 50 + years ago that there is still silent research ongoing... somewhere. Knowing the human mind - a breakthrough will some year arrive.

If teleportation of matter actually becomes available... talk about a technological game changer!!! GEEEEZZZZ!!!

Beam Me Up - Scotty!!!

Normal conversation . . . another reason to love a flybridge.

angus99 said:

Normal conversation . . . another reason to love a flybridge.

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I.E. ...

Talken with Ez through gentle fly-bridge breeze! Ya gotta luv it!!

Gonefarrel....I didn't use any of their products other than their excellent insight. As I recall, sourcing out the anodized perforated aluminum sheathig they use was the most challenging item.

Sound down is a good outfit

Conall

15 knots in an American Tug 395...
The video makes it sound much noisier that it was in person but you get the idea!

Bruce B said:

15 knots in an American Tug 395...
The video makes it sound much noisier that it was in person but you get the idea!

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Wifey B: I'm not the only one who's made a catch fishing today. AT has you hook, line, and sinker. Nice boat. Good choice if you go that way.

BandB said:

Wifey B: I'm not the only one who's made a catch fishing today. AT has you hook, line, and sinker. Nice boat. Good choice if you go that way.

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I do believe you are correct! Too soon to say but "we" are beginning to like the idea... (I've been sold for some time now truth be told!)
Bruce

Bruce B said:

I do believe you are correct! Too soon to say but "we" are beginning to like the idea... (I've been sold for some time now truth be told!)
Bruce

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Wifey B: But you still aren't completely sold till you can get out on one like you did today.

Sound level readings from 20ft CC

Just returned from a pleasant 7:30am cruise in 100 degree heat to take average sound readings from the helm, at ear level, trying to block wind noise (2-5 db) as much as possible:

• 780 rpm 80 db (idle)
• 3000 rpm 89 db
• 5500 rpm 94 db (normal cruise)
• 6200 rpm 100 db (WOT) with peak readings at 115 db

No wonder I get headaches after an hour. Definitely have to fabricate a box to cover the outboard.

makobuilders said:

Just returned from a pleasant 7:30am cruise in 100 degree heat to take average sound readings from the helm, at ear level, trying to block wind noise (2-5 db) as much as possible:

• 780 rpm 80 db (idle)
• 3000 rpm 89 db
• 5500 rpm 94 db (normal cruise)
• 6200 rpm 100 db (WOT) with peak readings at 115 db

No wonder I get headaches after an hour. Definitely have to fabricate a box to cover the outboard.

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Level at which sustained exposure may result in hearing loss: 90-95 dB (and don't ignore the wind noise, it all adds up.

Maximum allowed per day at 95 dB by OSHA - 4 hours.
Maximum allowed per day at 94 dB by NIOSH - 1 hour.

There are a few things you can do with an outboard powered boat to reduce noise.

You can replace whatever insulation is inside the cowl with an insulation that incorporates a mass loaded vinyl noise barrier. These are available in 1/2" thick.

You can have a canvas cover made for the outside of the cowl and sew in or make pockets to hold insulation with a mass loaded vinyl noise barrier. Particular care needs to be taken to leave the air intake open at the top back of the engine cowl.

Something that's common in the Keys and especially Key West on light tackle boats is a cover/cowl/cutting board/bait station over the outboards from gunnel to gunnel covering the entire outboard well a little higher than the O/B's and leaving room for full turns and tilt.

All 3 will significantly reduce noise on an outboard powered boat.

makobuilders said:

Just returned from a pleasant 7:30am cruise in 100 degree heat to take average sound readings from the helm, at ear level, trying to block wind noise (2-5 db) as much as possible:

• 780 rpm 80 db (idle)
• 3000 rpm 89 db
• 5500 rpm 94 db (normal cruise)
• 6200 rpm 100 db (WOT) with peak readings at 115 db

No wonder I get headaches after an hour. Definitely have to fabricate a box to cover the outboard.

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I just find those numbers staggering and would quieten with sound insulation. What kind of engine is that? I know you said 60 hp 4 stroke. I don't know if you noticed the numbers I posted from a 60 hp Yamaha equipped similar CC.

http://www.boattest.com/review/edgewater/192_155-cc

At 780 RPM, you're at 80 dB. At 1000 RPM, that boat is at 67 dBA.
At 3000 RPM, you're at 89 and they're at 74
At 5500 RPM, you're at 94 and they're at 86
At WOT you're at 100 dB and they're at 90.

I think I just realized part of the difference. They're measuring dBA and I'm assuming you're measuring dB?

BandB-

I didn't have a chance to log sound levels versus frequency, which would be more useful information. Perhaps I could calculate dbA with that info?

In any case, I like all three of Keysdisease's suggestions. The engine is a new Mercury Bigfoot 60hp and there is no sound insulation in the cowl cover. I'll search to see if I can find some mass loaded insulation in Qatar. If not then I can bring some back from vacation this summer in America.

I like the idea of installing it both inside the cover and also on a canvas engine cover, so in effect there would be two layers. A lot simpler to build those than to create the hard fiberglass box.