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Gentlemen,
I am going with your recomendations on soundown (1 1/2") for the engine rooms. Does it seem like a good idea to insulate the freeboards as well as the rest of the boxes or is that unnecessary? Any input is much appreciated.

Matt

Matt,

Literally, every square inch of sound proofing that can be added to the engine spaces will further reduce mechanical engine and generator noise. The back sides of the companionway panels, forward bulkhead, under the wings, hull face, etc.

For bulkhead mounted equipment such as Raycors and battery switches, make up mounting blocks the same thickness as the sound proofing. Mount those directly to the bulkhead and sound proof around them. Cover the blocks with the silver tape when you do other seams. The equipment will now mount flush with the sound proofing, be solid to the bulkhead and not sink into the sound proofing.

Sound not only transmits through solid surfaces like the engine box itself, but also bounces off any other surface that hasn't been sound proofed. The more you reduce those hard surfaces, the quieter the noise will be.

Don't sound proof horizontal shelf surfaces or below the high water line of the bilge.

Wow! That's one tidy job! I am working on mine now and oh boy do I have an appreciation for what is shown in that picture.

Thanks again Capt Pat for your very detailed response. Will do.
Matt

I put soundown on my boxes a couple of years ago, and it makes a difference. I have a gasser, and while its always been quiet, at troll you almost can't hear the engines at all. I bought the materials through the Sounddown guys I think in Mass., and the guy I dealt with was really helpful in getting my order right (how much attachment stuff per sq. ft. of material--that sort of thing). Good product, nice people.

John,

The trick to a well laid out engine room is plan ahead. Make sure you know everything that will be mounted and run before you start and do a pencil layout on paper before you start mounting stuff and running wires.

That way all wires can be run in a loom.

After Pat did the sound down on Buddy Boy, I laid out the mounting on paper. Where something had to mounted with a block, the sound down was cut to the exact dimensions to the mounting block so as to not squish the sound material down which is a poor installation job.

Even where there is a screw for a clamp, use a spacer as to not draw down the insulating material which reduces its effectiveness.

Thanks Bruce, but I am doing it after the everything is installed. I noticed a big difference just by gasketing in the engine boxes so they have a tight fit all the way around. I lined the side panels under and between the engine boxes with Sounddown and that that helped a lot too. Now I am attacking where the wings connect to the gunnels which seems to be where a lot of the sound is seeping from. It is almost civilized with what I have done already, but I'm trying to make it wine and cheese capable. I'm also "packing out" the engine boxes where they meet up for a tighter close so that I don't need two inches of foam weather striping to fill in the gaps.

After looking at this picture I might take a crack at taking the antifreeze overflow tank and the fuel filter/seperator off and cover the mid bulkhead with Sounddown, like you explained. They are the only things mounted to the bulkhead besides wires so it might be doable.

By the way, my engine boxes have Divinycell glassed into the underside to make them stronger (cut out the plywood) and the boxes themselves seem to hold the sound down pretty well set up like this. Weighs a lot less than Sounddown and provides stiffness too. Looking at the Divinycell it seems like it is a very good sound insulator.


Thanks for the tips. JJJ

Capt.Pat, when you say "Don't sound proof horizontal shelf surfaces or below the high water line of the bilge. " this means that on underside of the cover of the engines I shouldn't put sound proof material ? Sorry but it becames a litle bit confused on my head. I didn't arrive (yet) to that part but I am really doing a step by step repair based on this site and mainly on your tips. I am on the SuperHiperBoringSandingPhase on the inside but it goes. Thanks again.

I was working the Miami Show and missed this post.

What I think the Captain is saying is that there is no need to insulate below the waterline because we don't care if noise transmits underwater. We want to stop noise from getting out of the engine space and into the cabin or cockpit so any floors or bulkheads that adjoin the engine space with these areas should be insulated.

An exception might be below the forward bulkhead if the bilge is open forward for water flow. I know of some people that have used the "barrier" only (lead replacement) found in the middle of Soundown insulation to make a "flap" from the bottom of the bulkhead that hangs down into the bilge to the bottom. This will reduce noise travelling into the bilge and forward under the cabin but will allow water flow.

The basic concept is to "keep the genie in the bottle." A tightly sealed engine space well insulated with an engineered air path for combustion air that takes into account noise will result in a quiet boat.

Steve Moyer
Soundown ft lauderdale
954 761-9188

Soundown Salem MA
800 359-1036

I think by horizontal surfaces, Capt. Pat was referring to generator or battery shelves, not the gunnels or engine box.

I sound proofed the engine boxes on all three sides, under each engine, then going out board from underneath each engine, that next compartment bottom and then finally to the outboard wings.

Wow! What a difference. Then I heard a buzzer sound that I only heard when the port engine ignition was turned on but before the engine was actually started.

Thudddddd, am I going too fast for you?

Getting back to it, after the sound proofing, I heard the noise even when the engine was running. That how queit it was. It was coming from the tuna tower. I located the wire but didn't know what the wire was. So, being of minimal knowledge about things like this, I cut the wire. For the last three yrs, things are great.

How much did I spend for the sound material? Nothing! It is thick carpet from a house. Yeah, I tested the flamabiliy. Good carpet is flame resistent.

Capt. Dick:
I’m picturing the inside of your engine boxes lined with red shag circa 1973 so it looks like the dash board of a customized 70’s era Ford Econoline Van with a mural of a scene from the Hobbit painted on the side or maybe a Molly Hatchet Album Cover look…All joking aside, nothing like saving a few bucks with being creative and can’t beat it if it works!

Not sure about the 'below the waterline' surfaces. If those surfaces are bare fiberglas won't the sound bounce off to other surfaces? Soundown has a product specifically for those surfaces as explained to me by their rep. Bet he chimes in before the next full moon. He lurks about waiting for our posts on his favorite subject.