Trying to reduce the engine noise

[Summers420us]

Been a while since anyone posted on this subject. Anything new? Anyone take on this task and win or loose the battle?

 

[Glassman]

I went looking for my old post on the "other" site when I did the sound deadening material install back in the day and couldn't find it....hmm
To the degree that I installed the material it worked well. Some have gone over and beyond with even better results. I'm sure that I could reduce the sound level even more if I had a mind to do that, but then I'd lose my ability to shout," what honey? I can't hear you!"

 

[Summers420us]

Anyone else have any success here that they want to report?

 

[njmr2fan]

I had considered using secondskin noise reduction products http://store.secondskinaudio.com/. They have a layering system that starts with MLV (Mass Loaded Vinyl) and then goes from there. Ive had great success in past cars using a spray on product of visco-elastic membrane that turns vibration energy into heat basically. It was called QuietCar by www.quietsolutions.com, but I haven't been able to find it. Someone told me lizardskin bought them out http://www.lizardskin.com/sound-control-insulation.html.

My wintertime idea is to spray the entire inside bulkhead wall of the swim deck, then apply something on top much like a secondskin system. After that Id like to randomly glue some acoustic blocks in there to disrupt the resonance and absorb the sound from the exhaust. Ive always maintained that there is as much noise coming forward from the swim deck as there is from the engine compartment. Once I do complete it I'll see if I was right I guess.

 

[BakedZiti]

So I was swimmimg at the back of of boat last weekend and a buddy of mine noticed a black plate over the exhaust opening at the stern, he thought removing that would make it louder outside the boat but may be causing some of the reverb inside. Granted he was just guessing but thought I'd throw it out there, thoughts?

 

[4wheeldeal]

Interesting read, I'm wondering what are the conclusion?

 

[swatski]

Interesting read, I'm wondering what are the conclusion?

There is always something going on with that! No one has found a silver bullet, yet, but we are getting a bit closer every year.
And if you like to read, there is a plenty, LOL.
https://jetboaters.net/threads/another-soundproofing-thread-the-raamat-experience.11872/

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[4wheeldeal]

There is always something going on with that! No one has found a silver bullet, yet, but we are getting a bit closer every year.
And if you like to read, there is a plenty, LOL.
https://jetboaters.net/threads/another-soundproofing-thread-the-raamat-experience.11872/

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I do like to read up on things, I have OCD forsure! I'm new so I need to catch up.

 

[swatski]

I do like to read up on things, I have OCD forsure! I'm new so I need to catch up.

Oh, you are in the right place! LOL.

I think it is terribly impolite to welcome a new member with a "use the search engine" treatment. But I will say, there are several good, really in depth threads here. So - use the search engine! LOL And if you find yourself reading about an "old" or "dark site" -- it refers to the older Yamaha jet boaters forum, not as popular as this one, LOL.

Mine is the second Yamaha jet boat and as much as I love them, sound deadening is one of the major issues, still. I have spent a lot of time tackling this, and came out with some observations. For me, I think that trying to emulate car industry approaches has limits here, particularly when it comes to the number one strategy: mass loading. I find that the way fiberglass hull responds to mass loading treatments (such as Dynamat Extreme and equivalents) is dramatically less impressive than what you get with a car panel. I think it is a matter of simple ratios of the mass of the dampener you are applying to the mass of the panel you are trying to silence -- which is many time skewed comparing a thin metal car panel and a fiberglass hull.

Consequently, I have shifted my attention and the ongoing efforts towards lighter absorbing materials (such as Insolite).

But one thing is for sure -- the more discussion and real life TESTING of various approaches, the better the results will be.

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[4wheeldeal]

I have about 8 pages under my belt and checked out a bunch of links. You sure have done a lot of work! I like the latest engine hatch seal. One thing I didn't see any follow up on was putting sound proofing under the carpet in the rear compartments. He said it worked great but like you said about more testing was it tested before and after? I know this is a new boat but jets are loud and I don't know if my wife realizes it so I need to do some quick updates of she gets annoyed so I don't have to hear about it.

 

[swatski]

One thing I didn't see any follow up on was putting sound proofing under the carpet in the rear compartments.

Oh that is definitely worth doing.

I convinced myself in an instant when a seat was lifted in the strdb side (empty) storage compartment while under power. The amount of noise from the engine coming through was remarkable. Definitely worth sound deadening those bulkheads between the engine compartment and storage.

One thing to keep in mind is -- you may want to install a Perfect Pass down the road, which mounts on the side of the engine compartment.

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[robert cabrerea]

My 1st was the exciter 135 single. It was a loud. 2Cycle. I used 2" foam with aluminum paper side in the whole engine bay it was a bit better. When thinking about upgrading to a 4 cycle single in the sx190 I was hopeful the noise levels would be better. It may be a 2 db reduction not much. So. Im ok with the trade off of a good looking run about thats a bit louder than i like. I dont think our efforts to supress noise will be effective enough. Without adding xtra weight. Keep up the good work. Yamaha should work on it as well.

 

[d_coyne1984]

I spent some time moving around my AR192 this past season and I agree that I think the worse problem is the fairly wide open back end of the boat. It seems like there is a drum effect back there with all resonances from the engine bouncing around with no soft surfaces to slow them, which then travel through the gunwales and the bilge. I am going to give this theory a test this spring by trying to add some deadening back there. As far as I know, nobody has given this much of a try yet. I did add two inch seat foam from the fabric store (it is fire retardant) under the fuel tank hatch a while back and I do think that made a difference, although nobody else would probably realize it unless I removed it with them on board. I'll let you all know how that goes, but it's going to be a while still before I get to pull my boat out of storage up here in MN.

 

[d_coyne1984]

I finally tested my theory with success. I stuffed some 2' x 2'6" pieces of 2" thick, open cell foam back there through the maintenance holes next to the cleanout port and it made a considerable difference (at least to my ear, I didn't take any measurements), especially at low to mid-range RPMS. The next task I will have is to open it up completely so I can really get in there and glue some pieces into place and add some more. I really think the think, open cell stuff does more to slow the sound waves and reduce the resonant frequencies we hear on our boats better than anything else, but you also leave yourself a lot more susceptible to molding. So far the piece covering the bottom of my fuel tank hatch has been fine, but there is a lot more water in the back of the boat... I'll update how mine holds up over the season.