Sound Insulation

[conchy joe]

Faithful,

I am getting ready to move on to sound insulation in the engine compartment of my 28 FBC. I just installed a Panda Fisher 4.2kw geneses but am leaving the sound insulation/fiberglass box off because I want room to do maintenance, etc, on it. This is my first 3600 rpm generator and boy it is loud. Not to mention the cummins 4bt's make some noise too.

Anyhow, I was thinking about using Soundown 2 lb /2" vinyl foam to insulate the deck, forward and rear bulkheads, and hull sides.

Anyone have any experience with this product or have any suggestions on a better product?

Thanks.

[John F.]

I don't know what to recommend, but, when I did some Soundown stuff on my B31 gasser, the Soundown rep. I ordered from was really helpful in explaining what he thought would work best. It worked out really well too.

[Joe E]

I spoke with Steve at Sound Down. Very helpful. He recommended 1lb 1.5 inch for my 31. I will warn you it's very expensive. To ship. Joe

[conchy joe]

Luckily I can pick up locally. Thanks.

Anyone else have any comments/ideas?

[Yannis]

Troy,

I assume you placed the genny between the two motors. What is the problem to keep the cover and undress it when you need to do maintenance?
The thing is that with the b28 you need insulation only for the genny, you don't care for the engine noise as you're way up there and you barely hear it.
I have a friend with an Albemarle; there you should see what means real noise...

[conchy joe]

I placed the genset to the outside of the starboard motor and it's LOUD. I may put the fiberglass sound shield back on once I have 100 hours on the genset as it was used and I have found that someone tried going through it and I have found quite a few things that were ass backwards.

We will /sleep on the boat a lot and entertain friend so quiet is very important.

[JimmyG]

I have the same situation I put in a Next Gen and God is it way louder then my old Mase, I wish I got the hush box now...going to try insulation

[Marlin]

I put in the 3.5 next gen, been nothing but a maintenance issue, constantly have to pull the l wing bracket off to remove the hush box,made alterations on the hush box to remove in pieces, I tried sounddown, no luck, similar outside installation

[Wursty]

I have a Panda 4 and use the sound shield and this casing will bring down the noise a lot. I fact I find the vibration more noticeable than the noise using the sound shield. I have mine mounted port outboard side on my 31.

[JimmyG]

I put in the 3.5 next gen, been nothing but a maintenance issue, constantly have to pull the l wing bracket off to remove the hush box,made alterations on the hush box to remove in pieces, I tried sounddown, no luck, similar outside installation

Does the hush box help? I have to do something I can't think straight when its on

[keysdisease]

Gentlemen,

Joe E said Soundown recommended 1.5" 1lb for his boat. As a rule of thumb:

1 lb is for gassers, 2lb is for diesel

This has to do with the frequency the engines operate at. Diesel lower frequency calls for more mass to reduce noise transmission.

Also, there are compromises. As the 31 has engine boxes a 2 lb product just makes the box too damn heavy, so 1 lb is a reasonable option.

Conchy Joe is looking at our top of the line stock insulation, a good choice for a diesel boat when installed in the right places. We typically don't use barrier (heavy) products on hull sides because we don't care about noise going outboard. Acoustic foam for absorption is Ok on hull sides, but there just isn't enough real estate on a B31 engine room hull side to make this really worthwhile. Aft Bulkhead 1lb is adequate as the other side is not the cockpit but under the cockpit and noise still has to get through the deck.

Gasket and combustion air paths are some of the biggest contributors of noise. Leaky hatches and boxes can contribute 5 to 10 Dba to noise levels. Hull side vents are the quietest, anything else is just noisier.

Vibration as mentioned by Wursty, and a very inexpensive way to significantly reduce vibration is secondary isolation mounts under the entire generator, this is in addition to the factory mounts. This is money well spent if you have a couple inches of vertical clearance. For generators up to about 8Kw maybe $30 each, you will need 4. They need to be specified based on the weight of the generator.

Also the mounting of the muffler and the exhaust hoses should be looked at. Try and keep the pluming off any bulkheads that might transmit vibration to the cabin.

The factory insulation on a sound enclosure can be upgraded by moving up from the factory acoustic foam to a barrier foam composite product (1" 1lb). We carry this in peel and stick which works great on generator enclosures.

Happy to help, feel free to give a call and we'll do our best to bring you some peace and quiet.

Steve Moyer
Soundown Ft Lauderdale
954 761-9188
www.soundown.com