Noise reduction and mufflers

[CodFather]

Does anyone know if you can put mufflers on the Detroit 8v53. I want to reduce the noise on my boat and I'm not sure the best way to go about it. Any ideas to help???

Thanks ,
Marshall

[Boatsb]

You need big mufflers but the noise is also from the intake and engines themselves. Backpressure will kill a detroit.

[Salty Dame]

When you find out what silencer will work I'd be interested to know how to get them in without major surgery. The machinery noise is a large part of it underway but any one that hat ever handled lines on a 1969 41 conv. with 8V53s backing into a stall will only talk about the exhaust. The noise is not a myth, it's real folks.

[Angela]

I have no advice, but rather a question arising from this inquiry. Don't these, or perhaps some, of these DD already have mufflers? I've got this big oval round black fiberglass thing that I think says Vernatone on it which is located along the hull side, after the motors but way before the end of the exhaust pipe. Gee if I had to replace that, it would require a lot of effort in dismantling a closet on one side, and a head sink/cabinetry on the other.

[Boatsb]

Some us have the old mufflers and they just don't do much. I think they are just old and worn out. Newer ones may be a pita it better but detroits don't run quiet.

[CodFather]

Ok I have heard of Back pressure and detroit. I will ask Detroit diesel themselves they will be able to give me the low down there.

I am just wondering if anyone has added anymore soundproofing in the engine compartment and if it made enough difference to be worth while?

If anyone did this what did you use and was there any other places than on top of the origional material that it should be placed.

"ANGELA" I would love to know if what you have is a muffler. What engines do you have?

thanks again,
Marshall

[rwappleton]

Ours has the verno.......What Angela said also on 6-71TI's. The noise is noticeable in the salon underway, downright noisy in the aft cabin and because I am a motorhead pleasant on the aft deck.

We are changing hoses on the entire system and the mufflers on the 43DC slide forward with just a small amount of surgery in to the engine room.

We will be doing a quiet down exercise using several different methods acquired from this site and my automotive background.

I am going to do before and after db checks. I will publish those numbers, what we did and a few pictures also.:cool:

[Angela]

Marshall, I have the 8v92TI engines. Just went and verified - yes, they are Vernatone mufflers. I think the idea of having a muffler there was an original design because there are original access hatches in the corresponding closet and head on each side of the boat to get at them (but they won't come out through that hole, that's for sure); however, I suspect the ones I have now were installed in 2000 during the refit to make the boat an inspected vessel since they look a whole lot younger than 33 years old, but I can't be certain about that. It looks like the whole exhaust system was refurbished at that time, including removal of the metal exhaust tubes off the back of the engine and being replaced with big fiberglass tubes in the engine room.

As for sound, it's really only loud downstairs. In the salon, it's pretty darn quite, and at the flybridge, you can barely hear them running. Because my engine rooms were worked over during the inspection process, there was about 4" thick rockwool covered with aluminum sheeting applied to all of the walls and ceilings of the engine rooms. While I have been removing that stuff from the walls because it covered up everything that I need to maintain, I did leave it on the ceilings and I think that has done a lot for making the salon comfortable from a noise perspective while underway. I don't think I could sleep downstairs while underway, but Ed's daughter slept all the way from Bimini to Miami in a room right next to the engine room....then, again like MikeP recently said, teenagers can sleep through anything.

Oh yeah....on the aft deck, you can't hear yourself think....but, I, too, love the sound of my DDs singing.

[gbharrington]

Ours has the verno.......What Angela said also on 6-71TI's. The noise is noticeable in the salon underway, downright noisy in the aft cabin and because I am a motorhead pleasant on the aft deck.

We are changing hoses on the entire system and the mufflers on the 43DC slide forward with just a small amount of surgery in to the engine room.

We will be doing a quiet down exercise using several different methods acquired from this site and my automotive background.

I am going to do before and after db checks. I will publish those numbers, what we did and a few pictures also.:cool:

I am VERY interested in your results

[Salty Dame]

I have no advice, but rather a question arising from this inquiry. Don't these, or perhaps some, of these DD already have mufflers? I've got this big oval round black fiberglass thing that I think says Vernatone on it which is located along the hull side, after the motors but way before the end of the exhaust pipe. Gee if I had to replace that, it would require a lot of effort in dismantling a closet on one side, and a head sink/cabinetry on the other.

These boats do indeed have mufflers they just are not very effective. Also remember these are 8V53 naturals and will be noisier than turbo engines. I checked on up to date vernas and they recommended ones that measured about the same as the existing ones so I cant imagine much improvement vs work involved. I wish it weren't so. I just keep a large supply of ear plugs.

[CodFather]

Ours has the verno.......What Angela said also on 6-71TI's. The noise is noticeable in the salon underway, downright noisy in the aft cabin and because I am a motorhead pleasant on the aft deck.

We are changing hoses on the entire system and the mufflers on the 43DC slide forward with just a small amount of surgery in to the engine room.

We will be doing a quiet down exercise using several different methods acquired from this site and my automotive background.

I am going to do before and after db checks. I will publish those numbers, what we did and a few pictures also.:cool:

I'll be really interested in this as well! Send it to me if you don't mind when your done.

[CodFather]

These boats do indeed have mufflers they just are not very effective. Also remember these are 8V53 naturals and will be noisier than turbo engines. I checked on up to date vernas and they recommended ones that measured about the same as the existing ones so I cant imagine much improvement vs work involved. I wish it weren't so. I just keep a large supply of ear plugs.

My 8v53s have nothing that resemble mufflers! Straight pipe!

[saltshaker]

Yes Ang those are mufflers. I had them on my 46C and we needed to replace them when I repowered. The new ones were the same size except the intake and discharge ports were larger. I also redid all the soundproofing in the ER. Huge change overall. A lot of the reduction in noise was from going from a naturally aspirated Detroit to a turbo charged Detroit. The mufflers needed to be replaced. We discovered that there was a bad baffle in one of them. Soundproofing makes a huge difference. Before I did it you could hear pumps cycle and the AC compressor noise was much louder. I used SoundDown for the ER. I can't remember the thickness but it's a thick vinyl layer sandwiched by two layers of closed cell foam with a mylar outer layer. It was either 3" or 4" total thickness. I highly recommend this stuff. Removing the old stuff is pretty simple. It's screwed in place and not glued. Mine was in great shape in most parts but some areas were in poor shape. All of it came off easily. I stripped the ER of my 46C in less than a day. My engines were out and we moved the generator forward ahead of time so this made the work a whole lot easier. This is a good DIY project but there are some tricks to it. Cutting, fitting and taping off the individual sections isn't that tough. The key is to leave no gaps. A good carpet foam and carpet cut down a lot of the sound. If you're redoing the carpet or pan to go with a hard flooring, an underlayment barrier is great for knocking the noise down in the cabin. Yes these Detroits are loud but you can quiet the boat down considerably. My 46C was not too bad when finished. You could have a conversation in the salon without yelling. My 65EB has a solid overhead in the ER so there are no hatches or seams to leak noise. It's surprisingly quiet in the salon when running at cruise speeds.

[rwappleton]

Our project will begin in August and we will post results as we move forward:cool:

[q240z]

The original ER sound insulation on my Chris Craft Connie 52 was a sort of press board material that gave up over the years. I went through and ripped down the scrappy remains, then, at the suggestion of somebody on this board...maybe captddis?...I installed duct insulation. You can get it by the roll at Graingers in 1" and 2" thicknesses. It did a good job quieting down the salon from the rumble of my DD671s. What it didn't help was the harmonic rumble, but it was a lot quieter and the price was right.

When I installed it, I seam sealed between panels and made sure it was tight up to bulkheads. For best results, any hole or gap that will let sound through should be avoided.

ymmv
Q

[DCMY #92]

I've replaced both the original mufflers and added Soundown to the engine room in our 1965 41 DCMY with 6V53 Naturals.

The boat was originally gas powered with 3.5" exhausts. The previous owner installed the DDs but did not enlarge the exhaust. After several exhaust valve problems I enlarged the exhausts to 5" (the minimum for the 6V53. This required replacing the original 3.5" mufflers with new 5" Vernatones of the same design. The new mufflers are much louder than the originals, but the engines are much happier.

Installing Soundown to get useful results is very complicated. Any gaps or paths that the noise can "leak" through will eliminate much of the benefit. The original engine room air intake and Saloon wall arrangement used by Hatteras made an effective Soundown installation very complex. See the thread "1965 41 DCMY Refit" on this forum for the details of the modifications we employed to prevent engine noise from entering the Saloon via the air intakes. There are probably other methods that would have worked, but at a minimum the back side of the Saloon sidewalls would have to be completely covered with Soundown - including the built-in book cases, A/C box, etc.

[jim rosenthal]

I've thought about tackling this on my 36C, but always chickened out. I would have to do the hatches and floors, and also the areas inside the salon walls where the engine air intakes are as well. It seems like a great deal of expense and trouble without knowing whether it will help the noise level inside the boat.

That said, the Cummins engines are less noisy than the Caterpillars I had before, and the mufflers that were installed with the Cummins have helped a bit.

[Canuck Dennis]

I am replacing the factory vernatones on m,y 43 dc, 6-71's N series 310HP with custom made horizontal water lift vernatones to suit the dimensions I have without major cabinet destruction, will be doing in Nov.

[eze2bme]

Dennis - I'd be very interested in how this new set-up works for you - please keep me posted as I have 6-71N's also. Thanks.