I found that new engine mounts really cut the noise from my engine a lot. I think because the old ones were hard, they were transferring a lot of the noise and vibration straight to the structure of the boat.
Andy C&C 40 Peregrine Andrew Burton 61 W Narragansett Newport, RI USA 02840 http://sites.google.com/site/andrewburtonyachtservices/ +401 965-5260 > On Aug 29, 2014, at 7:05, Eric Frank via CnC-List <cnc-list@cnc-list.com> > wrote: > > David, > On Cat’s Paw, I installed special sound insulation to quiet the noise of > our 30 hp Perkins diesel. Decided to make noise measurements in the cockpit, > the cabin just forward of the engine, and all the way forward in the V-berth > (using a cheap dB meter app on the iPhone). 2 inch thick sound foam with a > special sound-adsorbing backing on the wooden engine housing in the cabin > (sides, front and top) and on the sides of the cockpit lockers. Just too > hard to get to the underside of the cockpit floor. It made only a small > difference in sound level - maybe a dB or two (I think 3 dB is a factor of > 2). When talking to a professional sound person when we separated a large > room with wooden sliding doors in our rental apartment downstairs with > special sound-absorbing materials, professionally installed, I was told that > even a small gap in the insulation would basically make the whole thing > pretty ineffective. 90 percent coverage with insulation would let much more > than 10 percent of the sound through. That job really worked - they left no > crack uncovered and it really blocks the sound. So my guess is that unless > every exit point surrounding the engine were insulated, it would make little > difference (and I left the whole cockpit floor uninsulated). Also the engine > can transmit sound by vibration through the engine mounts - perhaps new ones > would help - have not tried that. But as it stands, pretty disappointing. > > See you at the Newport rendezvous in September - I can show you what I did. > > Eric > Cat's Paw > C&C 35 Mk II > Mattapoisett, MA > >> From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of David via >> CnC-List >> Sent: August 28, 2014 6:22 PM >> To: CNC CNC >> Subject: Re: Stus-List Engine Sound Insulation >> >> Well I heard from one about the not-so-great results from installing engine >> sound insulation...anybody else want to chime in with an opinion about >> whether it is worth it? >> >> David F. Risch > _______________________________________________ > This List is provided by the C&C Photo Album > > Email address: > CnC-List@cnc-list.com > To change your list preferences, including unsubscribing -- go bottom of page > at: > http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com >
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