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Boat quiet?

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Re: Boat quiet?

Postby chariotdriver » Sun May 03, 2020 7:37 pm

Another method:

https://www.eastwood.com/lizard-skin-so ... gJd1vD_BwE

Several other brands popped up. I may be giving one a try.
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Re: Boat quiet?

Postby Ahusk » Sun May 03, 2020 7:45 pm

So apparently I am going down the boat quiet rabbit hole now also. I spent some time messing around while waiting for my trailer axle parts to dry and ended up ordering the same meter that Viking has.


My boat has full carpeting transom to bow, floor to under the top of the gunnel. It also had a full length gunnel tray and side covers with access holes that are made with MDO and covered with foam and vinyl.




I have some suspicions where some noise may be eliminated but I will wait until I get the meter to play with that.

What is interesting is how much the carpet deadens the sides and how little hydroturf does. I have attached a video. I start in the middle where it's carpeted and has a gunnel tray. Go to the bow where there is more open space but still carpet. I can here the difference but it's hard to perceive in the video. When I get to the back where the swim deck triangle is and no carpet there is a shocking difference. It's a very small unbraced area and it's still very loud. At the end I tap on the swim deck from underneath where there is hydroturf and it's deader than the bare aluminum but not by much. Unfortunately, the video doesn't do justice to how much difference there really is.

I am thinking carpet may be a cheap way to quiet down some of the resonance in bigger boats.

https://youtu.be/AoNwFO_65KA
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Re: Boat quiet?

Postby viking » Tue May 05, 2020 9:15 am

A general thought. If somebody is playing a trombone inside your cabin, the volume can be painful, and all he is doing is blowing air and flapping his lips. If you view your boat as a V8-powered trombone, with your head inside the bell, then there ya go. The dominant frequency of the trombone is determined by its length. This will also be true inside a boat, but then the question becomes "which length(s)?" A possible way to sort this out is to analyze the sound for the frequencies with maximum power. Then identify what is vibrating at these frequencies. I have some really old sound software that may be helpful. Newer may be better...

This thought is complicated by the fact that low frequencies are easily excited by high frequencies. For example, a middle C will excite the C one octave lower. So it is possible that a middle C on the side of the boat will create a lower C standing wave inside the cabin.
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Re: Boat quiet?

Postby Benny » Tue May 05, 2020 3:14 pm

viking wrote:A general thought. If somebody is playing a trombone inside your cabin, the volume can be painful, and all he is doing is blowing air and flapping his lips. If you view your boat as a V8-powered trombone, with your head inside the bell, then there ya go. The dominant frequency of the trombone is determined by its length. This will also be true inside a boat, but then the question becomes "which length(s)?" A possible way to sort this out is to analyze the sound for the frequencies with maximum power. Then identify what is vibrating at these frequencies. I have some really old sound software that may be helpful. Newer may be better...

This thought is complicated by the fact that low frequencies are easily excited by high frequencies. For example, a middle C will excite the C one octave lower. So it is possible that a middle C on the side of the boat will create a lower C standing wave inside the cabin.



Viking, you lost me with all that jibberish! I will just buy a box of ear plugs. LOL
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Re: Boat quiet?

Postby Eagle1 » Tue May 05, 2020 9:28 pm

Benny, You don't need eye plugs with a diesel. I just picked up two pallets of body sound insulation used on Hummers. 10 dollars for both. Going to try to quiet down the 460 Gasser in the Almar.
Last edited by Eagle1 on Tue May 05, 2020 10:00 pm, edited 1 time in total.
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Re: Boat quiet?

Postby Jetdaddy77 » Tue May 05, 2020 9:44 pm

Eagle1 wrote:Benny, You don't need eye plugs with a diesel. :Drink: :Drink:


Only when Dennis drives! (Ask me how I know!) :Laugh1: :Laugh1: :Laugh1: :Laugh1:
'93 North River 19', Kodiak 350, 3 stage, and plenty of smart marks sold
'04 Boice Titan 22', Stroked 6.7 LS, Hami 212
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Re: Boat quiet?

Postby Riverjohn » Tue May 05, 2020 9:50 pm

Jetdaddy77 wrote:
Eagle1 wrote:Benny, You don't need eye plugs with a diesel. :Drink: :Drink:


Only when Dennis drives! (Ask me how I know!) :Laugh1: :Laugh1: :Laugh1: :Laugh1:

I have always wondered why Dennis had a box of Eye Plugs in the passenger seat :Laugh1: :Laugh1: :Laugh1: :Laugh1:
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Re: Boat quiet?

Postby Ahusk » Sun May 10, 2020 9:22 am

Long story made as short as possible. The meter fluctuates usually about 1db but I used the high end readings. .

5700rpm cruise on digital tach. This is much higher than the normal cruise but I was loaded full of camping gear and family in first test so I used that number for consistency. As a note. The noise seems to be the same on cruise from 5000 to 6000. Above that the supercharger gets loud.

88db - full of camping gear and family.
93db - solo with no gunnel blockers
90db - with gunnels blocked no gear

See picture below but my boat has direct passages down the gunnels for noise from the engine. I blocked them with boat bouy and a sweatshirt and made a 3db gain. More noticeably it almost eliminates all supercharger whine from the operator station. I will build some permanent blockers out of something and retest. Top rpm at 93 degree ambient temp did not change with passages blocked.

I still think there is a bunch of improvement to be gained soundproofing the doghouse. Just need to find a non 200 dollar way of testing that theory.
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Re: Boat quiet?

Postby Eagle1 » Sun May 10, 2020 12:32 pm

Great test. My Almar had total foamed gunnels with a pipe for cables. It makes a difference. Going to try a cut some weight on the Pweld remodel and add some sound stuff.
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Re: Boat quiet?

Postby Tyingflies » Thu May 21, 2020 10:06 pm

Really, I think it's in everyone's best interest to keep the boats as quiet as you can, unless racing ofc. The more people that botch about noise, the more people complain then all the govt starts to listen and in turn start to regulate. Jet boaters, have respect in front of those shirtless bait casters on shore that are only jealous we can get to those places they cant.
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Re: Boat quiet?

Postby desperado » Fri May 22, 2020 12:55 pm

"have respect in front of those shirtless bait casters on shore that are only jealous we can get to those places they cant."

Wow I was one of those shirtless bait casters until I joined the REBEL crowd :Drink: :chicken:
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Re: Boat quiet?

Postby smitty » Tue May 26, 2020 12:08 pm

My dB meter (Protmex MS6708) just arrived. Now, just gotta figger out how to run it …
boat, motor, squirt nozzle
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Re: Boat quiet?

Postby Eagle1 » Tue May 26, 2020 10:57 pm

Smitty, Did you get your boat out of the snow yet.?
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Re: Boat quiet?

Postby smitty » Wed May 27, 2020 9:20 am

Yes. :master: :chicken: :smoking: :Drink:
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Re: Boat quiet?

Postby viking » Wed Oct 14, 2020 1:05 pm

A Kingfisher add says the following:

Whisper Pack Sport Jet Sound Dampening package (Over 20% decibel reduction over conventional construction)


If the decibels are reduced by 20%, and given that Decibels are a log scale, and given that a relatively loud boat is ~90 dB, and given that each 6 dB is perceived to approximately halve the sound level, this implies that the Sound Dampening package reduces the perceived volume to 1/8 of the un-dampened volume.

Does anybody know what this Sound Dampening package is, and is there before/after dB data available?
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Re: Boat quiet?

Postby hilljackian » Wed Oct 14, 2020 3:41 pm

An FYI for those who don't know that mufflers are required equipment on a powerboat to be permitted for entry into the HCNRA wild & scenic river:

  • "Valid motorized craft is defined as rigid hull craft with water-cooled exhaust (inboard shall have through-the hull exhaust) that are driven by propellers or jet pump(s), that are equipped with mufflers and/or other noise reduction devices. Motorized river craft must be at least 12 feet in length, but no longer than 39.6 feet in length"
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Re: Boat quiet?

Postby Riverjohn » Wed Oct 14, 2020 5:07 pm

hilljackian wrote:An FYI for those who don't know that mufflers are required equipment on a powerboat to be permitted for entry into the HCNRA wild & scenic river:

  • "Valid motorized craft is defined as rigid hull craft with water-cooled exhaust (inboard shall have through-the hull exhaust) that are driven by propellers or jet pump(s), that are equipped with mufflers and/or other noise reduction devices. Motorized river craft must be at least 12 feet in length, but no longer than 39.6 feet in length"

Not sure what if anything this has to do with the Thread or the above post. :?: :?: :?:
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Re: Boat quiet?

Postby viking » Wed Oct 14, 2020 6:38 pm

...or "other noise reduction device". Like a turn-down can.
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Re: Boat quiet?

Postby hilljackian » Thu Oct 15, 2020 7:38 am

Riverjohn wrote:
hilljackian wrote:An FYI for those who don't know that mufflers are required equipment on a powerboat to be permitted for entry into the HCNRA wild & scenic river:

  • "Valid motorized craft is defined as rigid hull craft with water-cooled exhaust (inboard shall have through-the hull exhaust) that are driven by propellers or jet pump(s), that are equipped with mufflers and/or other noise reduction devices. Motorized river craft must be at least 12 feet in length, but no longer than 39.6 feet in length"

Not sure what if anything this has to do with the Thread or the above post. :?: :?: :?:


This is a thread about making the boat more quiet, isn't it? Adding a muffler can make the boat more quiet and if you are going into the HCNRA you need one anyway so it might change the calculus on where in the process of spending $$$ and effort to make the boat quieter a person installs mufflers. Not to mention that this knowledge might keep somebody from getting a ticket by the Forest Cops or prevent them from getting blacklisted by the HCNRA, so it felt like a friendly thing to share.

Based on my interactions with law enforcement agents, I would put the odds of successfully making the turndown can = noise reducing device at pretty low.
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Re: Boat quiet?

Postby Nater11 » Thu Oct 15, 2020 3:56 pm

viking wrote:A Kingfisher add says the following:

Whisper Pack Sport Jet Sound Dampening package (Over 20% decibel reduction over conventional construction)


If the decibels are reduced by 20%, and given that Decibels are a log scale, and given that a relatively loud boat is ~90 dB, and given that each 6 dB is perceived to approximately halve the sound level, this implies that the Sound Dampening package reduces the perceived volume to 1/8 of the un-dampened volume.

Does anybody know what this Sound Dampening package is, and is there before/after dB data available?


Feel free to correct me, but a dealer told me that the “whisper pack” was marketed with the external mufflers in place of the old style internal mufflers, paired with superior dog house insulation.
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