I think I finally quieted my Yamaha!

[swatski]

Winter project. Any suggestions or things you would do differently? I'd like to quiet down our AR190 so we can take a civilized cruise on the water and be able to talk. do you think that wrapping the inside of the the swim platform and adding some noise absorbing eggcrate would reduce sound from that big hollow area?

It will help, I would not expect a miracle but filling all those large spaces around the engine bay and in the stern does make a noticeable difference.

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[Ronnie]

Im getting ready to refurbish my boat and more targeted sound reduction is on the list so this thead has been helpful.

something to keep in mind is that the 230 hos have a much higher max rpm thn the 240s (10,200 v 7,800) and a high pitched whine after 9,800 rpm (at least mine did).

I looked up the decibel meter that boat test used once, as i recall it was something available at radio shack for under $60. I bet a place like frys electronics would have something comparable. As for location of the meter during testing they never really state it so i just measure from the driver's seat.

I think i would be happy with a 2 db decrease or any decrease for that matter as what i was told /read the the db scale is logrithmic such that a 3 db reduction equates to a 50% reduction in sound/noise. What is confusing for me is seeing decreases in db (on iphones and ipads) at some rpm but not others, which makes me question the accuracy of the readings since i thought the decrease in db would be linear / predictable.

 

[Glen]

Tracking...

 

[njmr2fan]

I've looked for the DB-3 product that was sold through Home Depot and its no longer available. If anyone locates it please post.

 

[Jgorm]

I have a high end full spectrum db meter. Without taking an initial measurement with the same meter you are totally wasting your time. Placement and angle of the microphone have a huge influence on the reading. It's gotta be with a couple inches to compare readings. You would need to mount it on something like a tripod. You would also have to measure the wind at the time. I spent a lot of time taking readings in my car before doing sound proofing. I gave up. The road, speed, traffic, etc were huge variables. Same road, exact same speed, etc and it still has large variations.

 

[gmtech16450yz]

I might have some info on sound reduction in a couple weeks.

I'm kind of a freak about exhaust. haha. I've modified the exhaust systems on literally everything I've owned from generators to motorhomes. Seriously. I'll put a couple pics of my latest exhaust project, my Echo leaf blower with a modified engine and a silencer from a Yamaha YZ85. lol. The end result of that project was WAAAAAYYYYY more power and WAAAAAAYYYYYY quieter than stock even being a California 64dB quiet version. My neighbors love me! (It doesn't hurt that I blow the leaves out of their yards too.)

So when I got this '17 212 Limited S, I naturally "needed" to mod the exhaust. haha. My original thoughts were to see if I could increase power and wasn't worried that much about the noise levels. So the first thing I did was to remove the plastic resonators and shorten the whole system piping. Then I made those full 3" outlets to eliminate the stupid rubber flappers and the fact that they necked down to 2.5" at the outlets. The end result of those mods was, as most everyone on here knows is the case with power mods to these boats, absolutely NO increase in top speed or time to plane. It sounded good, more like a performance boat than a family cruiser, but it was too loud above 6500rpm. The type of boating we end up doing usually involves a lot of high speed cruising, and last Saturday we spent a bunch of time sitting at either 7000 or 7800rpm. Driving home I decided to embark on Boat Exhaust Mod V 3.0. lol.

I pulled the entire exhaust out of it again last Sunday and ordered some parts. My plan is to put the plastic resonators back in, after sound deadening them a little bit of course. That would just get me back to "stock" though, and if I was going to go quiet, I wanted to go QUIET!!! After all, it's not like it has a glorious sounding V/8 that you love to hear. It's a couple of little 4 bangers. I don't need to hear that! So I had a pair of Moroso Spiral Core mufflers sitting on the shelf in my shop, and guess what? They're stainless, have no fiberglass packing that can get wet and they're 3"! Yay! So along with the plastic resonators I'm going to put one of these spiral core mufflers in each side. I've used these mufflers on 500 and 800hp V8's and they definitely quiet down the exhaust without losing a ton of power. Each of these mufflers is good for around 400hp without significant power loss from restriction so with each of them only having ~180hp going through them they "shouldn't" hurt power at all. We'll see.

So I'll let you guys know what I learn on my own boat quieting quest. I've already done a bunch and it's made big differences. I have a feeling if the exhaust gets way quieter that I'll next be dealing with the intake noise. I've built Hemholtz resonators into exhausts and intake systems before, I may end up doing that on this boat. The Hemholtz resonators are cool because you can target a specific frequency and pretty much totally eliminate it. It's as simple as finding the offending frequency by using an app on your phone, then building a resonator that matches that frequency. I've totally eliminated that dreaded freeway "drone" on cars and trucks by building resonator tubes into the exhaust. And the best part is they don't really effect power at all. That's basically what the plastic resonators on our boats are, Hemholtz resonators. After I'm done with this round of exhaust mods, I plan on checking and zeroing in on any frequencies that are still too high, whether it's the intakes or exhausts.

My goal is to make my boat sound like it has electric motors even at 7800 rpm and to be able to whisper to my passengers while going 50mph! We'll see.

Here's my leaf blower...

 

[gmtech16450yz]

I have a high end full spectrum db meter. Without taking an initial measurement with the same meter you are totally wasting your time. Placement and angle of the microphone have a huge influence on the reading. It's gotta be with a couple inches to compare readings. You would need to mount it on something like a tripod. You would also have to measure the wind at the time. I spent a lot of time taking readings in my car before doing sound proofing. I gave up. The road, speed, traffic, etc were huge variables. Same road, exact same speed, etc and it still has large variations.

Exactly! Using meters for before and after testing on stuff like this is almost impossible. Speaking of meters though, I took my phone out when we were on a lake last weekend. It was SOOO quiet I had to see how quiet it actually was. It's the first time I've ever seen sound level readings in the teens! Now this was quiet!



The 74dB was me touching the phone to take the screenshot. The little blips in the middle was my stomach gurgling. lol. Here's where I took those readings...

 

[buckbuck]

@gmtech16450yz
You will instantly obtain 'Super Hero' status if you come up with a solution that the rest of us dummies can do to quiet our boats.

 

[buckbuck]

https://www.amazon.com/Moroso-94055-Polished-Stainless-Muffler/dp/B001GC3VJS/ref=sr_1_fkmr0_3?ie=UTF8&qid=1516144163&sr=8-3-fkmr0&keywords=Moroso+Spiral+Core+mufflers
I would gladly pay $500 to modify my two engines and make them quiet.

 

[swatski]

My goal is to make my boat sound like it has electric motors even at 7800 rpm and to be able to whisper to my passengers while going 50mph! We'll see.

OMG I would so want it, I would pay big bucks for that!

But - I'm not sure it's doable!
(just trying to rile you up, @gmtech16450yz, LOL).

In all seriousness though, the pumps are also MAJOR offenders. Unlike other boat propulsion systems, the final drive w/ impeller/wear ring operate above the water w/boat on plane.


In my experience, I've noticed some improvement when using plastic wear ring inserts, but those are not as durable as the OEM by far.

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[LionShare]

This has been discussed extensively in the past. I think the consensus is that it is not an issue. Same engines do very well in skis where the space is a lot more confined. Cooling is open loop water so the blowers are just for safety - to get rid of fumes and prevent potential ignition of fuel vapors.

Of course the air intakes access to fresh/cool air may be an issue if you obstruct the passages/openings in the back of the engine bay, that needs to be considered.

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This sounds like as must-do MOD but what Swatski mentioned was the first thing that came to my mind. Having no memory of how air is routed to the intake, will this sound deadening procedure hinder this process in anyway?

 

[swatski]

This sounds like as must-do MOD but what Swatski mentioned was the first thing that came to my mind. Having no memory of how air is routed to the intake, will this sound deadening procedure hinder this process in anyway?

Funny you should mention this, we were just debating this topic:
https://jetboaters.net/threads/wakesurfing-ballast-on-swim-deck-air-intake-issue.16254/#post-279173

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[d_coyne1984]

Im getting ready to refurbish my boat and more targeted sound reduction is on the list so this thead has been helpful.

something to keep in mind is that the 230 hos have a much higher max rpm thn the 240s (10,200 v 7,800) and a high pitched whine after 9,800 rpm (at least mine did).

I looked up the decibel meter that boat test used once, as i recall it was something available at radio shack for under $60. I bet a place like frys electronics would have something comparable. As for location of the meter during testing they never really state it so i just measure from the driver's seat.

I think i would be happy with a 2 db decrease or any decrease for that matter as what i was told /read the the db scale is logrithmic such that a 3 db reduction equates to a 50% reduction in sound/noise. What is confusing for me is seeing decreases in db (on iphones and ipads) at some rpm but not others, which makes me question the accuracy of the readings since i thought the decrease in db would be linear / predictable.

Different materials (say neoprene mat vs. open cell foam) may dampen some frequencies while having little effect on others so it could be that the materials being used here are effective at dampening the resonance at some RPM levels, but get overtaken at others and have little effect. ...or it could easily be the phone mic. I know, I'm helping... Lol!

I should pitch to the firm who who were brought in to deaden the motor lab at my work to see if they would engineer a kit for my boat and then put the kit up for sale after it has been tested. They could make A LOT of money.

 

[06CCDMAX]

Following

 

[Jgorm]

Different materials (say neoprene mat vs. open cell foam) may dampen some frequencies while having little effect on others so it could be that the materials being used here are effective at dampening the resonance at some RPM levels, but get overtaken at others and have little effect. ...or it could easily be the phone mic. I know, I'm helping... Lol!

I should pitch to the firm who who were brought in to deaden the motor lab at my work to see if they would engineer a kit for my boat and then put the kit up for sale after it has been tested. They could make A LOT of money.

That's why the west marine engine insulation kicks ass. Open cell, closed cell with a mass damper in between.

 

[Minh Nguyen]

At 50mph I don't see how anyone can hear anything...the wind noise alone would be so loud. I log 3k+ miles on my bicycle each year and at 20mph it's hard to have a conversation with my training partner that's next to me. I think speed has a major impact on those db readings and the placement of the mic will give a different reading if moved a few inches below the windshield.

 

[Jgorm]

But you have a windshield. I'd test it out of the water at specific rpms before and after. It won't be exact, but engine noise will be similar.

 

[swatski]

At 50mph I don't see how anyone can hear anything...the wind noise alone would be so loud. I log 3k+ miles on my bicycle each year and at 20mph it's hard to have a conversation with my training partner that's next to me. I think speed has a major impact on those db readings and the placement of the mic will give a different reading if moved a few inches below the windshield.

Interesting point. It made me think.

Then I overruled it: wind in your ears or no wind, loud is loud!
LOL.

Personally, I don't need a dB meter. The first Yamaha JB I ever rode - 2012 SX190 - was so f@cking loud I started laughing on the test ride, couldn't believe it. Bought it anyway - figured I will sound-deaden the beast make it quiet like a Bentley, easy peasy - right? (well, I was proven wrong...!!!!)

There is a big difference between a 2012 190 and a 2016 240. The latter is much, much better but still PLENTY of room for improvement.

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[swatski]

That's why the west marine engine insulation kicks ass. Open cell, closed cell with a mass damper in between.

Man, I'm really torn now. I like this insulation a lot. But it seems best suited/designed as a continuous barrier material - and I'm not sure I want to build an "enclosure" around the engines given @buckbuck comments.
I may end up taking an easier/softer way! - with just using a bunch of unbranded acoustic foam wedges and panels to fill in as many voids and spaces as I can reach and cover the bulkheads etc.

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[Jgorm]

Man, I'm really torn now. I like this insulation a lot. But it seems best suited/designed as a continuous barrier material - and I'm not sure I want to build an "enclosure" around the engines given @buckbuck comments.
I may end up taking an easier/softer way! - with just using a bunch of unbranded acoustic foam wedges and panels to fill in as many voids and spaces as I can reach and cover the bulkheads etc.

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I bought it after seeing a twin Cummins diesel 37' boat open and close the engine compartment. HUGE difference. It's plenty flexible. I coated the dog house on my motorhome. I coated most with the thick version but had clearance issues and had to use the 1/2" too. It's expensive but works great. Use it on the areas with direct sound contact.