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Old 12-11-2021, 02:28 PM   #21
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I believe that is the function of the loaded vinyl layer in the middle. The foam acts as a decoupler and the loaded vinyl absorbs the sound (vibrations).
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Old 12-11-2021, 02:35 PM   #22
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I believe that is the function of the loaded vinyl layer in the middle. The foam acts as a decoupler and the loaded vinyl absorbs the sound (vibrations).
I was replying more to the drum room scenario.

In my understanding you are correct in your main point, I believe the foam can act as a decoupler. However, MLV itself won’t absorb sound but rather redirects them. Sound absorption materials turn the waves into heat. Sound proofing like MLV redirects the waves (which decay over distance, hence why airspace between barriers is useful).

For an engine room walls from the cabin interior or other noise sensitive area , I think sound proofing would be great (with green glue or something that decouples it so it just doesn’t transfer to the fiberglass ) from the cabin, and absorbstive materials elsewhere in the engine room to try to absorb it.

It’s been said that even a small gap in soundproofing material will still pass half the noise through!

I’ve been immersed in this stuff lately, not for a boat but a house. Had six 15’ rolls of 2lb per sq ft MLV installed last week!
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Old 12-11-2021, 03:41 PM   #23
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Yes the little holes can let out a bunch of noise but they are also the most difficult to close up. I am starting with the big obvious area, the engine room hatch which is pretty much the size of the cockpit. We finished that area and will see how much different the sound will be in the spring after we launch. Then if we still need to do more we will.
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Old 12-11-2021, 08:54 PM   #24
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Staggered studs and green glue type treatments are great for land based installations. A staggered stud wall with MLV laced between and green glue attached drywall is probably as good as it gets without getting extreme. A "floated" floor stops transmission through the floor. These treatments are for when you have space, every inch on a boat on the other hand is precious.

Drum risers are sometimes floated or decoupled for the reasons stated. Low frequency noise has power, that's why if you're at a stop light and a car 2 lanes over has a bass bazooka in the trunk you feel the bass but can't hear any singing or other instruments. The mid and high frequency sounds are stopped easily by safety glass (which is decoupled) and a steel car. High frequency finds its way through the smallest cracks, why gaskets are important. Turbo whine will squeeze through a very crack.

There are only 2 ways to reduce noise, put mass between you and the noise, or get further away from it. Decoupling kind of fakes out noise into thinking its further away because it interrupts the wave path. Foam on either side of a mass layer increase the performance of noise reduction considerably.

Following best practice for boats is a sure way to get good performance. Some land based treatments will crossover to boats (MLV is used for both) but usually boat products perform better for the space they take.

1lb sq ft MLV = STC 28
2lb sq ft MLV = STC 32

Vibration is noise. Secondary isolation of generators and care to be sure exhaust components are not transmitting exhaust pulses into overheads and bulkheads makes for a quieter boat at anchor.

Engine mounts also have a performance lifespan, and because they deteriorate so slowly they are seldom noted as a source for noise.

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Old 12-12-2021, 09:40 AM   #25
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So it seems that anyone with a four stroke diesel (especially a four cylinder) should consider the investment in flexible mounts.

I didnít need them with my 6-71, but they are smooth by nature. However my V-6 will make your teeth chatter in a certain rpm band.
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Old 12-12-2021, 04:24 PM   #26
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My Vicem had two sweet 1,100hp V10s. The engine room was directly beneath the main salon and near helm. It had quite a bit of decoupling systems and baffles/ screens/ foam for deadening sound in the ER. Lower frequency diesel grumble was not a problem. The whine of both turbos boosting up when I’d change from no wake idle to 22kt cruise speed was thrilling, like a jet getting ready to takeoff. But after a while its mid and higher frequency pitch was tiring, plus it interfered with speech normal speaking level.

Steve Moyer of Soundown was supremely helpful and talked me through the process of finding the worst noise leaks using a sound meter on my iPhone (it was $2 I think). Before I took the time to investigate with the sound meter I had planned giant carpet underlayment, assuming that all the noise was just coming through the floor from the ceiling below. This plan was less than perfect because the salon has beautiful inlaid teak and Holly with custom cut area rugs.

With the iphone app I discovered that the most offensive mid and high frequency noise was leaking through wire chases, holes near the engine air exchanges, and resonating in the lockers under the salon seating, just like a guitar body will amplify the strings.

Steve advised me to get simple foam to tightly stuff in and around the wiring and conduit in the chases, this was good for an immediate 10dB cut of the objectionable high frequency whine. Then I measured out the square footage needed to lay MLV at the bottom of every locker and wooden void. We translated that to the appropriate size roll and I had it truck shipped to my marina. I found a carpet layer who was also a boater. He and I made templates then he cut the MLV to exactly conform to those resonating spaces. That was good for another 10 dB in midrange.

My wife and I could converse at a normal level while also running music even though we were blasting along at 20 kn and more. I did not need to buy any new carpet. And we did not need to cover the beautiful salon sole.

Soundown MLV. NIOSH Sound Level meter.
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Old 12-12-2021, 09:12 PM   #27
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Very happy that worked out well for you.



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Steve Moyer of Soundown was supremely helpful and talked me through the process of finding the worst noise leaks using a sound meter on my iPhone (it was $2 I think)
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Old 12-12-2021, 10:45 PM   #28
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I installed Sound down on all my hatches with their perferarated aluminum shield. Works incredibly well. I have a sheet of 2" left over. How much do you need?
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Old 12-13-2021, 08:13 PM   #29
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If somebody in the next room is making too much noise, what's the first effective remedy (besides yelling at them)? Close the door. Likewise, the most bang for the buck is to close off any openings from the engine room, no matter how tiny they seem to be. Electrical wires, throttle cables, plumbing, etc. are generally not sealed. Even placing new soundproofing around those openings will prove difficult. Spray foam to the rescue. Get a gun like this one and get good at using it. Even a little foam will make a big difference and, with things like a bundle of electrical wiring passing through a bulkhead, it will be easy to rip out and redo should you need to add or subtract from the bundle. Other items, like plumbing penetrations for the head, can be made more permanent by using more foam. $50 in foam can do what $1,500 in mass loaded vinyl can't.
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Old 12-13-2021, 09:05 PM   #30
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Quote:
Originally Posted by Marco Flamingo View Post
If somebody in the next room is making too much noise, what's the first effective remedy (besides yelling at them)? Close the door. Likewise, the most bang for the buck is to close off any openings from the engine room, no matter how tiny they seem to be. Electrical wires, throttle cables, plumbing, etc. are generally not sealed. Even placing new soundproofing around those openings will prove difficult. Spray foam to the rescue. Get a gun like this one and get good at using it. Even a little foam will make a big difference and, with things like a bundle of electrical wiring passing through a bulkhead, it will be easy to rip out and redo should you need to add or subtract from the bundle. Other items, like plumbing penetrations for the head, can be made more permanent by using more foam. $50 in foam can do what $1,500 in mass loaded vinyl can't.
I agree that sealing small holes is beneficial but not before you insulate the main surfaces first. Start with the big areas and finish with the small ones.
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Old 12-15-2021, 11:26 AM   #31
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I agree that sealing small holes is beneficial but not before you insulate the main surfaces first. Start with the big areas and finish with the small ones.
I did the opposite. Went with the $50/one hour foam gun soundproofing. Dropped 5db. Not sure I'd get much more spending $1500 in a complex panel installation after having sealed up the trouble areas. Most of them would be very difficult to seal with panels and then would have been more difficult to seal the small leaks that panels can't cover.

Get a decibel meter for your phone (free download) and really identify the areas where the engine noise is coming through. It generally isn't in a straight line from the engine to your ear. My "hottest" area was under the rear galley sink. The sink drain and FW had penetrations in the original soundproofing that went into the rear of the engine room in an inaccessible area to sound proof with panels. Another hot area was the forward head where the VacuFlush and FW penetrations went through the original soundproofing in to the engine room. The head was very noisy underway and, because of the vents in the head door, that noise was coming into the main area. I thought that the engine noise would be coming straight from the engine (easy to put panels between me and the engine), but most of the noise was travelling a circuitous path and coming from the front and rear of the main cabin.

Don't buy the orange canned foam. Doesn't look good.
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Old 12-16-2021, 11:40 AM   #32
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Originally Posted by bowball View Post
I was replying more to the drum room scenario.

In my understanding you are correct in your main point, I believe the foam can act as a decoupler. However, MLV itself wonít absorb sound but rather redirects them. Sound absorption materials turn the waves into heat. Sound proofing like MLV redirects the waves (which decay over distance, hence why airspace between barriers is useful).

For an engine room walls from the cabin interior or other noise sensitive area , I think sound proofing would be great (with green glue or something that decouples it so it just doesnít transfer to the fiberglass ) from the cabin, and absorbstive materials elsewhere in the engine room to try to absorb it.

Itís been said that even a small gap in soundproofing material will still pass half the noise through!

Iíve been immersed in this stuff lately, not for a boat but a house. Had six 15í rolls of 2lb per sq ft MLV installed last week!
Speaking of gaps. What have folks used to fill gaps in engine room access doors on the floors?
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Old 03-05-2022, 12:01 PM   #33
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Between the studs?

The information on Soundown has been very helpful. I have a studded ceiling in my engine room.

Question: Do I put the product between the studs and then cover everything with some product (a thin sheet of plywood??) to seal in the ceiling?

Or, do I close in the ceiling, and then put the product on the plywood?

Chris
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Old 03-05-2022, 12:17 PM   #34
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Engine room sound insulation

The Sundown cuts down on noise transmission especially the lower frequencies. However in addition to that, the best treatment for your overhead in the engine room is a perforated panel, not solid. A solid surface will reflect sound waves. A perforated surface is preferred however because it allows sound waves to penetrate into the void above, where it bounces around and is dissipated.

Perforated metal panels are not too expensive either.
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Old 03-05-2022, 12:37 PM   #35
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Speaking of gaps. What have folks used to fill gaps in engine room access doors on the floors?
I just got done using this self-stick stuff, which is really intended to seal between the canopy (called a cap in some places) on a pickup truck bed. It is also available in a self-stick one-sided version that costs more. I simply cut the double bubble stripping down the middle to get 40 feet of sound proofing.

It comes with alcohol wipes to clean the attaching surface. My engine hatches, like most Taiwan trawlers of the era, are a heavily soundproofed hatch that rests on a teak lip all the way around the opening. In the dark, I could see that my engine room lights were on. While the hatch was sound proofed, they were essentially opened a crack all the time. Not good. I attached the stripping, bubble side up, around the perimeter of the lip so that it was maybe 1/8th inch proud of the lip. The hatch is heavy enough that it pushes down, seals the engine room, and is still flush with the rest of the floor. A noticeable difference with a 30 minute installation and $30 in materials. If I accidentally pull it loose by sliding over the edge into the ER (in a drunken stupor?), I have enough to replace loose pieces for years.

This soundproofing, along with my $60 canned foaming of all ER perforations, has noticeably cut down on noise. I haven't taken another decibel reading yet, so I can't compare my $100 and 1 hour soundproofing to $4,000 worth of sound down and 10 days of work. And I don't think I'll need/add any complex/expensive soundproofing.

As anecdotal evidence of the effectiveness of my cheapo soundproofing, I'm now looking at purchasing a new tachometer. My tachometer, although new only 400 hours ago, has a mechanical hour meter. Every few seconds it ticks and a little indicator piece on the dial rotates. Maybe it ticks 10 times a minute and then a bigger tick when the .1 number on the gauge ticks forward as well. With my improved soundproofing, that tick has become irritating, like a grandfather clock in the library. I can't believe I put up with that so long, but I didn't used to notice it. I'm now looking to replace it with a tachometer that has a (silent) digital hour meter.
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Old 03-05-2022, 03:14 PM   #36
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I just put 2Ē 2 pound per square foot insulation from Soundown. I used the PSA backing and also used the glue on perforated nails stuck on with thickened epoxy. I wanted to be sure it would not fall down. I used some plywood and ratcheting poles to hold the insulation in place while the epoxy and PSA glue setup. Soundown says the PSA gets full strength in about 24 hours.
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Old 03-05-2022, 04:04 PM   #37
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Nice job Dave. It will be much harder now to hear the fuel rushing through the lines to feed those engines. Just kidding, seriously good looking job, I'm sure it should make a difference.
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Old 03-05-2022, 04:28 PM   #38
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I couldnít hear the fuel since the engines were so loud. Maybe now I can hear the fuel flowing through the linesÖ
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Old 06-06-2022, 10:58 AM   #39
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I have been working on the project for a bit now. I ended up having to refiberglass the bilges. There was water, oil, and sludge under the bottom fiberglass in some areas. removed all the old fiberglass (down to the concrete that is in the keel) and laid 4 layers of 1708 biaxial cloth.

Funny, I tried to get someone to do the work (as I had never fiberglassed before), but everyone was booked out for months. So, with some advise from one of the guys, I set out to do it myself. It's not perfect by any means, but I am generally happy with the result. A coat of primer and BilgeKote and it looks like new.

Now for the ceiling. I put in Rockwool Safe and Sound in between the floor joists. Then I tried to put a length of 1lb per sq foot of MLV. This is really hard to do in long sheets. It's flimsy and heavy to hold up. I had my wife helping and would have needed maybe two others to try and get it up.

After a frustrating few hours of trying to get a long sheet up its time for plan B.

I have perforated aluminum sheets that I bought for the finishing layer on the ceiling. I decided that I am going to cut these into smaller more manageable pieces (say 3' by 4'), glue the MLV onto them, and then put them up in sections with screws.

Will be trying that a bit later today to see how it goes.

Included are some pictures of the project so far.

Cheers,

Chris
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Old 06-06-2022, 10:59 AM   #40
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And one more pic...
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