The noisy 4D61 rides again

[rnummi]

When you say the sides of the pilot house your talking about the part that's molded right? As opposed to the 2 inch thick portion around the widows? I didn't know that was open. Where's the access? Either hull side of engine compartment? Obviously I haven't spent a lot of time below.

[Vic K]

Warren,

While I was going through my 'noise' period on my redo I had the good fortune to speak with an engineer from NASA about sound. Only wish I was smart enough to understand a quarter of what he said. I did grasp that sound is energy and you can reduce it basically two ways: absorb or deflect. He also said that if you had an area say 4 X 4 feet its not necessary to cover the entire area with a sound 'proofing' material. If you checker boarded the surface it will serve the same purpose. As you said the 4D61 has a timing gear not a chain or belt. This makes them damm near bulletproof but also noisy. Anything you do to adsorb or deflect the ( noise) sound will help. Had I removed everything from the boat and started with a fresh canvas I would have done it differently.
I'm content( translated means my wife is happy) with what we've ended up with. It's not perfect but it works for us . The 'blanket' I have, doesn't interfere with doing routine maintenance . At cruise rpms we can have a conversation as well hear the VHF. Also think at the present sound level and pitch I could be on the boat several hours at a stretch without going deaf.

Vic

[Sprig1]

Rnummi just crawl in either side and look up. It's a big space trying to figure out what to do with it. Also you have to get in there and bed the cleat that is mid ship. Vic since I have a total clean slate in my engine room what do you suggest?

[Vic K]

Warren,

If I had deep pockets like you and money and time was no object. I would clean every surface then apply about three coats of epoxy or at least alkyd enamel. Then do a detailed plan as to where each piece wire, hose and equipment was going in the engine room. There is a marine acoustical material ( I'll have to dig out the source) that has self adhesive backing. It comes in different sizes and thickness ( foil covered, with an acoustical layer that's sandwiched between foam). I'd apply that stuff to every surface. Then rebuild the engine covers to where they lock down tight over gaskets. Close up any opening where sound could escape. Plan a ventilation system (air in /air out) to the outside of the boat. Of course do the motor mounts. When I last checked on this material it was about ten bucks a square foot. The more you bought the price went down.
A lot of work but you'd have a very quite boat.

Vic

[Vic K]

Warren,

Look up MegaSorber. This stuff is lined but not with foil like I said. It's been a while since I researched sound reducing material.

Vic

[Sprig1]

Hay Vic that was sprig1 asking those questions not Warren. The last time I was at the marine consignment shop there was a big roll I will have to check if it's still there. The only way I'll get that material is if I can find a deal

[Vic K]

Sorry Chris. I'm suffering from Oldfartis.

[Beta Don]

I *think* this would be an excellent size blanket to lay over two poles like Vic did on his install - Vic could tell you for sure

http://www.ebay.com/itm/141307877350?_t ... EBIDX%3AIT

This guy has had a few of these for sale on eBay for the past 6 months or more, so make him a lower offer ($75?) and see if you can't get a deal on one of them. A cut or two for the exhaust or whatever and I have no doubt this would quiet down that noisy old 4D61

Don

[Vic K]

Don,

This what I bought and had custom cut to fit the engine. It turned out to be too heavy and too cumbersome.

Vic

[rnummi]

Did you foam all the way across the engine access panels? I.e. Does the panel rest on the foam?

[tego]

Rick, I applied soundproofing across the entire panel of the engine access hatches. Yes, the soundproofing rested on the lip around the opening. I was worried that the hatch wouldn't close completely but no problem. My soundproofing is 1 1/2" thick. I used wood battens (fore and aft) screwed to the hatch to help support the heavy soundproofing. I also used contact cement to mold the foam to the hatch contours. Works great! Ben

[rnummi]

Thanks amigo. That's what I'm doing as well. Dynamat extreme over the whole thing, followed by Dynamat Hoodliner. How about a the hollow tubes? Fill with closed cell foam? Cynically speaking, they could serve as floats if the boat sank. I'm kidding. At this point the covers are the most solid portion of the deck. I through em in the trunk to work on them at home... (and see my family again).

Seriously though, how about the underside of the rest of the deck? I've got enough Dynamat to do the whole thing or save it to line the engine compartment? You can cut it into smaller pieces to fit around the various pieces parts hanging on the engine compartment bulkheads.

[Vic K]

FYI: I had the pleasure today of taking a ride in a 27FC (' 84) 4d61 with a fully insulated engine compartment. It was great! The noise level extremely low. Made me jealous.
Vic

[rnummi]

Hmmm....a lot quieter? Or a little quieter (than yours)?

[Vic K]

Yep.

Vic