Sound Proofing Material Recommendations

[Searios]

Forgot to mention mould resistance.....

[Keysdisease]

I am not familiar with any wood product that won't burn. I did some research into cork sheet and found the most common binder is polyester. I did find a reference that treated cork might be rated as "fire resistant" which means nothing. I did find a flame test for a 50mm (2") cork board that resisted flame penetration for 4 hours at 1500*f. I doubt 6mm cork bits in a polyester binder would do as well.

6mm cork has an STC (sound transmission class) of 23. 3mm (1/8") of mass loaded vinyl (1lb sq ft) has an STC of 28. 6mm (1/4") of mass loaded vinyl (2lb sq ft) has an STC of 32. That's a pretty big difference.

STC: https://en.wikipedia.org/wiki/Sound_transmission_class

Cork can be a good thermal insulation and a decent decoupler when used correctly, that's why you find it in flooring, to decouple hard finish floors from the structural sub floor.

The reality is that combustibility just isn't that important in a fiberglass or wood boat. There is already so much fire load in a typical engine space like wood, rubber, lubricants, the fiberglass itself, that it's really not an issue. Vinyl / Foam composite insulation has been used in boats for decades.

For a steel or aluminum boat it should strictly be incombustible insulation, because the structure of the boat is itself incombustible.

I understand that you seem to have religion over cork, but unless the laws of physics are different in Hong Kong, 6mm of cork is not going to perform as well acoustically as 6mm of mass and especially mass in a composite of absorber and decoupler.

Originally Posted by Searios

@ Keysdiseas

Your mentioned examples might burn if exposed to an open flame - cork will not...it's cheap, available, fire "safe", noise and thermal insulating..

Is there a another product available out there with these properties?

The density and size of the cork mix is important - so make sure you order the right mix - follow the link that was posted earlier on...

Buy a roll from China, glue it on..

[DHeckrotte]

Fascinating subject. Back when I was an employed architect I was fortunate enough to work on theaters and symphony halls. Our sound consultant worked all over the world on land-based as well as cruise ship sound isolation as part of their main task of acoustical performance within the space; the fellow I worked with went on to work on sound control on submarines.

Anyway, the basics include: structure-borne noise and air-borne noise. The structure-borne noise is much tougher, isolating engines, motors, traffic, helicopter noise and all. The solutions involve motor- and engine mounts, vibration isolation, weight, discontinuity of structures, floppy or non-resonant structures. Much tougher when you care what your boat, or your cruise ship weighs. The other isolation involves air-borne noise, tackled with air tightness, gaskets, etc.: somewhat easier since stopping air leaks is at least doable with sealants, gaskets, etc. Any holes open between the source and the space you want quiet is worth tracking down.

[Keysdisease]

Excellent point. Good gaskets on hatches and sealed penetrations can account for 5-10 dba. The biggest bang for the buck in noise reduction is $20 worth of gasket.

And you are correct about structure borne noise. Not as straight forward as airborne noise, and sometimes very difficult.

As with any issue, figuring out the source of the problem is the first step. Airborne problems call for airborne solutions, which are what most people address, usually with insulation. Many think foam is the universal answer. Structure borne problems call for structure borne solutions, as you mention usually isolation mounts, decoupling, damping.

I have seen pumps that make bothersome noise with a home made enclosure over them and the owner wondering why he can still hear the noise in his stateroom.

Originally Posted by DHeckrotte

The other isolation involves air-borne noise, tackled with air tightness, gaskets, etc.: somewhat easier since stopping air leaks is at least doable with sealants, gaskets, etc. Any holes open between the source and the space you want quiet is worth tracking down.

[Searios]

I did test the cork vs the foam - the foam burned - the cork didn't....That experiment might not work in US though as things seems to be weird there now.

[FF]

The cost has dropped , many new cars have noise canceling mufflers.

Perhaps active noise canceling for the vessel would have better results than just No Noise?

[Jeff F]

Originally Posted by FF

The cost has dropped , many new cars have noise canceling mufflers.

Perhaps active noise canceling for the vessel would have better results than just No Noise?

That's a great point. My corporate offices have gone open concept in the last couple of years, and active noise cancellation has allowed that. I can look around and see people having conversations but have a very hard time hearing them. I think that similar systems have been installed on some airliners. Perfect for tuning to reduce certain categories of noise, and I would think very applicable to our boats.