cabin engine noise in 16 & 19 c-dory's

thataway · Posted: Sat Oct 13, 2007 7:20 pm Post subject:

Generally in boats, the sound reducing material is foam covered with mylar foil on the outer surfaces--and then there is a lead vinly material in the center. This is very efective in reducing sound--far more than paints or single layer foil materials. Soundown vinly/Foam is one example:

http://www.soundown.com/TECH%20SHEETS/Vinyl%20Tech1.pdf

http://www.starboardsupply.com/product_info.php/manufacturers_id/209/products_id/3013278

There are specific kits for lining the cowlings of outboards with this type of material.

dotnmarty · Posted: Sun Oct 14, 2007 9:10 pm Post subject:

Oldgrowth Dave-How about fabricating a nice bulkhead door like on the 22? Just a thought.

oldgrowth · Posted: Mon Oct 15, 2007 8:35 pm Post subject:

I want to thank all you people for your comments and ideas in ways of solving my engine noise. I like the idea of solving the noise problem at the source, instead of at my end. I still have a little research to do but it will be more on the ideas put forth by Warren, Ken, Mike or Bob. I would like to find a local supplier of some of these products so I can see them and have a better idea of what it is and how to build the enclosure.

Dave T · Posted: Mon Oct 15, 2007 9:06 pm Post subject:

I experienced the SAME problem as many of you on my 16' Angler. As a prototype (it has been on my boat now for 2-years) >> as it Does work pretty dang good. Smile

I used "foam-core" board that you can buy at your local Lowes or Home Depot.

Email me for pictures... mattea11@comcast.net

Dave T · Posted: Mon Oct 15, 2007 10:41 pm Post subject:

Ooops >> I forgot to say WHAT my "prototype" was... I built a Noise Reducer Bulkhead - that spans across the motor well. It is not too "pretty" (aesthetic's wise) but it does work well. Cuts the cabin reverberation by about one-half.

I don't yet know how to attach pictures to this post...so if you want some pictures, please email me at: mattea11@comcast.net

Dave T.
Brier, WA

marvin4239 · Posted: Mon Oct 15, 2007 10:55 pm Post subject:

Dave I goggled "outboard motor insulation" and came up with this web site http://secondskinaudio.com/viewproduct.php?id_product=315&gclid=CJezpNO0ko8CFQ2aOAod80WgfQ that seems to have what you are looking for.

Sea Wolf · Posted: Tue Oct 16, 2007 1:18 am Post subject:

Rather than try to build a soundproof enclosure around the motor, I wonder if a simple rounded baffle would be effective enough?

If the noise reduction would be signifigant just by reflecting the noise aft and away from the cockpit, there may be no need to build an elaborate chamber in which to enshroud the motor.

A sound reflecting baffle, made esthetically pleasing by making it transparent instead of opaque, could perhaps reduce the noise to acceptable levels.

Whether to make it of flat panels or to make it of compound curves would be an interesting study. It might be possible to find an existing plastic windshield off of a motorcycle, ATV, or some other vehicle that would do the job.

The first step, however, would be to experiment with a crude prototype to see if a simple baffle would be effective enough.

Just some thoughts to consider.

Joe.

oldgrowth · Posted: Tue Oct 16, 2007 8:56 pm Post subject:

C-WEED · Posted: Tue Oct 16, 2007 10:41 pm Post subject:

Interesting project.

Not sure how big of a difference there is between the cowling on your engine and a Honda 75 HP. To keep the look you might be able to insulate the 75hp cowling and slip it over your current engine cowling. If the fit is good the air intake should work the same. If it is doable, that would maintain the original airflow/clearance around the powerhead. I would think two layers of cowling with insulation would be a good noise reducer and maintain a factory look without much artistic effort.

ripple · Posted: Tue Oct 16, 2007 11:48 pm Post subject:

Has anyone tried using this Silent Running product?

http://silentcoating.com/sr_1000.html

I read a few reviews of it a while back and it sounds really good. I have no idea how it works in practice though. It is supposed to dissipate acoustic noise as heat. The attractive thing is that you paint it on so it can easily conform to the complex curves of an outboard cowl.

oldgrowth · Posted: Wed Oct 17, 2007 1:39 am Post subject:

ripple - there are many types of paint applications that are suppose to dramatically reduce the noise and vibration. A couple of years ago I tried one that had claims of almost word for word what Silent Running has.

I built a test tank that I could set my engine in while on the boat and run the engine in gear at high RPM’s. I used a sound meter to check the noise inside the cabin before applying the paint, then tested it again after three coats of paint that I applied inside of my engine cover.

It did reduce the sound from one to three db’s, depending on the engine speed. To my ear, I was unable to tell the difference between 85 db and 83 db, so I do not consider it a viable means or noise reduction.

Maybe if you painted the entire deck, splash well and cabin of the boat, it may make a noticeable difference but it is expensive and heavy. I am going my memory but I believe I paid around $100 for the gallon of paint I got which included shipping. The gallon of paint weighed 20 lbs m/l. You would need at least five gallons and maybe more to do the inside of the boat and from my experience, I don’t have much confidence in it.