Sound and Fireproofing Insulation Question

[jenglishsr]

We have a Californian 34 LRC and we are getting the old insulation stripped out below deck and replacing it with new insulation. We have a quote based upon the use of 1/2" and 1" insulation. Will there be an appreciable difference in the sound dampering between these two products? There is about $500 difference in the cost.

[Mirar]

Hi there , I don't think you actually referenced the type of insulation you were using but my ears twitched when I saw the mention of sound proofing and fire proofing in the same sentence. I built a 55 foot alloy cruiser and used rock=wool or navy board for insulation. It is made by Roxul and is totally organic, made from spun volcanic rock or slag. It is stable to 2000 F +/= and is also quite a soundproofer. It is pretty much the product of choice on commercial vessels for soundproofing/fire so I have 7 inches on my engine room bulkhead for instance, 3-4 inches everywhere. I bought it from C&I insulation in Vancouver , Canada. Heavy, for sure, but my boat is warm and fireproof and...quiet.
cheerio and stay warm and shhhh .ps, my boat is built to Dutch ice-class standards so maybe we have different cruising grounds.
Greg Janes

[DeepFrz]

You should be able to look up the insulation material that you were quoted and see the difference in noise attenuation. Much though depends on the installation and sealing off of the living spaces from the engine room. I would expect quite a large difference but that is just speculation without knowing what it is they quoted you. Some insulation has both sound absorbing and blocking qualities.

[Pelagic]

Noise is 80% structure borne, 20% air borne.
I just finished redoing my engine room with a number of products from Soundown.
This primer might help you choose
Soundown - The Woldwide Leader in Noise Control Engineering

[Mirar]

Hey there,,, To me, the sound down line looked like fuel to a fire, can't imagine that anything with foam is not going to burn like crazy. I used sound down in my last boat and after a few years the diesel fumes in the air had turned it to powder, falling everywhere and probably going through my turbo.For a live- in interior, it seemed more toxicity to breathe. Pulled the powder junk out and put the proper stuff in. I can weld right on top of the alloy with the Roxul insulation, a big plus on a metal boat. It is also not hydroscopic nor based on hydrocarbons.
On the other hand, my insulation project was in the order of $7000.00
cheerio,Greg

[kentobin]

Something new to look into. I'll be lucky to get 3.5 inches of insulation in my engine compartment and 1.5 every where else. Thanks Greg.

How It's Made - Roxul Stone Wool Insulation - YouTube