Benefit of adding engine box sound insulation on an R-21EC

[baz]

Subject: Benefit of adding engine box sound insulation on an R-21EC

I've read here that some R-21EC owners have added additional sound insulation in and around the engine box and wonder if there's real measurable benefit in doing this.

If anyone has in fact done this...

1) What material was used ?
2) What's the material cost involved and where was it obtained from ?
3) Do you have pictures of the installation available ?
4) Was a dB sound level measured at various RPMs before and after the installation and if so what were the results ? (easily done using a dB level mobile phone application such as Decibel 10th for an iPhone)

I did find this in an older posting on insulating sound... http://www.sailorssolutions.com/index.asp?page=ProductDetails&Item=SPM06 and wonder if anyone here has used this ?

Thanks... 🙂

 

[SGIDAVE]

Subject: Benefit of adding engine box sound insulation on an R-21EC

I've read here that some R-21EC owners have added additional sound insulation in and around the engine box and wonder if there's real measurable benefit in doing this.

If anyone has in fact done this...

1) What material was used ?
2) What's the material cost involved and where was it obtained from ?
3) Do you have pictures of the installation available ?
4) Was a dB sound level measured at various RPMs before and after the installation and if so what were the results ? (easily done using a dB level mobile phone application such as Decibel 10th for an iPhone)

I did find this in an older posting on insulating sound... http://www.sailorssolutions.com/index.asp?page=ProductDetails&Item=SPM06 and wonder if anyone here has used this ?

Thanks... 🙂

Hello BArry,

My 2013 21EC had the factory liner...it was saturated with water from the teak cup holder screws which had not bedding compound...hence wet foam falling from the top of the engine box...so I HAD to do something...I researched the options...Soundown (http://www.soundown.com/index_Marine.htm) appeared to offer the best sound attenuation with their "decoupling" layer. Get the 'barrier composite insulation' which has the decoupling layer in the middle. They also sell plain foam with foil backing called 'sound absorption material' which would be a lot like the Sailorsolutions.com product for which you provided the link.

Go to Soundown (http://www.soundown.com/index_Marine.htm) and read their material to better understand the strategy...and why sticking up plain foam with foil exterior won't help much. The decoupling layer is cruicial.

Look in my photo album to see my project pics. I bought my Soundown materials from Lowcostboatingstore.com (http://www.lowcostboatingstore.com/SOUN ... 9548.html#) which, in late 2013 offered the best prices on 1" and 1.5" foam. In my Yanmar-powered 21EC I used 1.5" thick on the top and 1" thick on the sides and ends. I used 1 can of Soundown spray adhesive (way too expensive) then switched to a Dow product from Home Despot. I bought their fastening kit but that is really unnecessary...the entire engine box has a 'core' so I'd used pan-head stainless screws 1/4" longer than the foam is thick plus a large fender-style washer and screw that into a small pilot hole. I WOULD use some spray adhesive too - just reinforce everything with screws/fender washers.

I could have gotten away with 1.5" thick everywhere but your boat with the Volvo D1 may be different. I used (2) pieces of the 32 x 54 size...one of the 1.5 thick and one 1" thick. I may have used the leftover 1.5" on one or both ends after covering the top.

As for objective difference...I measured about 3-5 db with a hand held meter. Subjectively it is better but not LOTS better. As I said, my engine box insulation was falling off, so I had to do something and elected to use the best product.

All the above details are included in the my original thread on the rehab of my motor box insulation here (viewtopic.php?f=5&t=4335&p=32032#p32032)

have fun!

dave