Questions about noise insulating the engine room.

[Ten Years Gone]

Hi Guys,

Hopefully I'm posting this in the appropriate forum...

My 250DA engine room is really loud while underway, almost to the point that I must shout at the admiral when sitting side by side at the helm. The only "insulation" that appears to be factory is a thin piece of foam rubber glued to the underside of the engine hatch. I want to use some kind of padding in the bilge to quiet the cockpit down. What if any, did SR use to accomplish this on later models/newer boats? Should I just go to Lowes and get the reflective bubble-wrap looking stuff, or is there a real science behind the materials and installation of genuine acoustic absorption products? Would the sound deadening mats that car audio fanatics use in their fenders and doors work? I know that stuff is crazy expensive for small sheets of it. I am thinking of lining the underside of the cockpit floor and the walls of the bilge with something. Would this work, or should I just enjoy the roar of my 300hp small block? :huh: BTW, I do have the factory snap in berber carpet, which is heavy as hell, but I've never used it. I like to be able to wash the cockpit out with a hose and not wrestle a carpet to do so. Is cockpit noise reduction a side benefit of having the carpet installed?

Your experiences and/or suggestions greatly appreciated!

 

[CliffA]

i just ordered a sheet of this due to positive comments from others that have used it before for reducing engine compartment noise...i ordered the 2" thick material....i hope to install it this W/E (if it delivers on time) in the engine hatch....it isn't cheap but good quality items rarely are....i found a 72" x 54" x 2" (27 square ft) sheet on sale for $180 on line which is the best price i saw...

cliff

http://www.soundown.com/Section 2 PDFs/2.1 PDFs/Vinyl Foam.pdf

 

[CV-23]

Let us know how it works....my 454 is pretty loud also under the floor, Mike.

 

[CliffA]

will do....i received the insulation yesterday but was dissapointed to find it did not have any adhesive applied, however i am impressed by the quality of the product itself....i spoke to Soundown today (great company to deal with) and they are sending me some mechanical fasteners that glue to the hatch with 3M 5200 and told me to use 3M Super 77 spray adhesive (available everywhere) along with the mechanical fasteners to install the insulation in the hatch to insure it stays in place....i must have ordered the insulation without the adhesive by mistake so i cannot blame the company i bought the insulation from.....apparently it can be bought with or without the adhesive.....i won't have the fasteners until next week so the installation of the foam will have to wait until the following W/E......unless family matters interfere........

cliff

 

[Ten Years Gone]

Thanks for the link...I'll check it out!

 

[lawndoctor]

I removed the OEM thin foam "insulation" from the interior of my engine box and installed this stuff a few years ago. It is fantastic. Previously when underway my wife and I pretty much had to yell to carry on a conversation. Now we can talk at normal levels. Made it major difference. Hope you get the same results guys.

 

[bmac]

You want to make sure you use Soundown insulation that includes a barrier layer of mass loaded vinyl between the decoupler and absorption layers , for the best sound attenuation. Soundown can't ship the spray adhesive, you need to procure it locally....and remember to get the mylar film tape if you need to join panels. This stuff works well to quiet noisy engine spaces.

 

[CliffA]

You want to make sure you use Soundown insulation that includes a barrier layer of mass loaded vinyl between the decoupler and absorption layers , for the best sound attenuation. Soundown can't ship the spray adhesive, you need to procure it locally....and remember to get the mylar film tape if you need to join panels. This stuff works well to quiet noisy engine spaces.

Thanks Brian.

The insulation i purchased does have a vinyl layer between the two foam layers and it has a silver reflective film on the side that faces the engine. My local Home Depot carries the 3M Super 77 spray adhesive. When I called Soundown for the mechanical fasteners they threw in a partial roll of 4" sealing tape as well at no extra cost. Great customer service.

Cliff

 

[CliffA]

will do....i received the insulation yesterday but was dissapointed to find it did not have any adhesive applied, however i am impressed by the quality of the product itself....i spoke to Soundown today (great company to deal with) and they are sending me some mechanical fasteners that glue to the hatch with 3M 5200 and told me to use 3M Super 77 spray adhesive (available everywhere) along with the mechanical fasteners to install the insulation in the hatch to insure it stays in place....i must have ordered the insulation without the adhesive by mistake so i cannot blame the company i bought the insulation from.....apparently it can be bought with or without the adhesive.....i won't have the fasteners until next week so the installation of the foam will have to wait until the following W/E......unless family matters interfere........

cliff

wanted to post a follow-up to my post in this thread....we finally got the boat out this W/E after i installed the sound deadening insulation....there is a significant reduction in the sound level at all engine speeds...at idle i can barely hear the engine running...while cruising the wife and i can carry on a conversation with just 'slightly' elevated voices....(wait a minute, maybe this point should be considerd a 'negative' instead of a 'positive').....we can hear the stereo much better while cruising......i even wrapped a small piece of the insulation around the bilge blower with large plastic ties which did help to lessen the sound of the blower while it is running.....

cliff

 

[E-man]

My insulation is starting to come off right by the latch on the engine hatch. I sprayed that 3M Super 77 on it and I thought it held until next trip up to the lake I raised the hatch to check the oil and it fell off again. Maybe I need to do it again and put pressure on it for a while?

 

[moparlvr4406]

I did my 240 box with Dynamat Extreme
I would estimate 40-50% noise reduction...no db meter available
it did an awesome job on the noise AND the heat

 

[CliffA]

My insulation is starting to come off right by the latch on the engine hatch. I sprayed that 3M Super 77 on it and I thought it held until next trip up to the lake I raised the hatch to check the oil and it fell off again. Maybe I need to do it again and put pressure on it for a while?

i used a combination of mechanical fasteners and the Super 77 spray for the insulation on top of the engine hatch and so far so good.....i just used the Super 77 spray for the insulation on the sides....if it does not hold i will have to install mechancial fasteners there as well.....

one thing i remember from reading the instructions on the Super 77 spray is to get the strongest bond possible spray both surfaces and wait a few mins until the glue becomes tacky then attach the insulation to the hatch....that is what i did.....

cliff

 

[E-man]

i used a combination of mechanical fasteners and the Super 77 spray for the insulation on top of the engine hatch and so far so good.....i just used the Super 77 spray for the insulation on the sides....if it does not hold i will have to install mechancial fasteners there as well.....

one thing i remember from reading the instructions on the Super 77 spary is to get the strongest bond possible spray both surfaces and wait a few mins until the glue becomes tacky then attach the insulation to the hatch....that is what i did.....

cliff

I did wait for the amount of time the can said. Thanks.