quiet boats

A discussion on ways to reduce it.
mike99705
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quiet boats

Postby mike99705 » Sat Mar 10, 2012 1:41 pm

I am in process of putting boat back together and have learned a lot from this forum. I want to have the quietest boat with good drivability that is reasonably possible. The subject seems to have died. Is that because all aspects have been covered and waiting on new technology or are people tired of talking about it.I believe a quiet boat is what will keep airboats on the water in the future, even here in alaska we have people that are trying to ban them in areas.So if anybody has an idea even wild ones about sound reduction please keep sharing them.
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cntry141iq
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Re: quiet boats

Postby cntry141iq » Sat Mar 10, 2012 2:57 pm

it has pretty well been covered on here ... it is a very touchy subject in florida ...
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Re: quiet boats

Postby Whitebear » Sat Mar 10, 2012 4:24 pm

There are a lot of threads and some darned good pix on SA. It seems a set of standard automotive mufflers, with an X pipe either in the muffler (2 in/2out) or a separate X-pipe and a quiet slow turning prop gets the job done the best. There are nearly infinite variations on the theme with just as varying results. Obviously once the Exhaust is quietened the next loudest thing is the prop that stands out to the sound detectors in most folks ears. Lots to search and research right here on SA.
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Re: quiet boats

Postby cntry141iq » Sat Mar 10, 2012 6:17 pm

automotive style engine boats can be quieted down to the point of being able to talk on them while running dry ground for miles with no problem. Problem is the a/c boats or DD boats cannot take advantage of the lower reduction ratios to turn a prop slow enough to be quiet. That is where it gets heated.
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Re: quiet boats

Postby Waggin » Thu Jan 03, 2013 12:43 am

well been talkin to my pop's... he talked about directing the noise....would be helpful and it dont matter what you run for power a simple shield around the cage that would keep the sound going backwards ( and also add to safety if a prop came apart) anybody ever tryed it? i'm gonna but have no db meter to check it out so I'll have to go by ear....I like the idea of a quiet boat. heard one the other day that was louder at idle than mine at cruise speed...yes it got me wet....i do love the sound of a fine tuned V-8 but i like slidin on my boat more. I havent rode on an aircraft boat yet and the gearbox boat got me wet so I didn't notice the noise...sorry hard to pay attention listnin to eight cylinders poppin off like that.....kinda like tryin to watch a race when two Hunnies are kissin each other?????
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Re: quiet boats

Postby Waggin » Thu Jan 03, 2013 12:47 am

what rpm are we lookin for? i can cruise on a plane at 1600 but the boat feels heavy at 1800 its a nice ride but still think it could be quieter.....seem to have engine noise to a minimum but what else can be done? throw some ideas out here
cntry141iq wrote:automotive style engine boats can be quieted down to the point of being able to talk on them while running dry ground for miles with no problem. Problem is the a/c boats or DD boats cannot take advantage of the lower reduction ratios to turn a prop slow enough to be quiet. That is where it gets heated.
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Wild Bill
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Re: quiet boats

Postby Wild Bill » Thu Jan 03, 2013 1:14 am

Mine worked nice but some people said it was quieter than the jet boats and some said it was more noticeable. With the 3 blade superwide most people didn't mention engine noise but the signature thump thump of the blade it self. Coming up river they herd the prop 5 minutes before I got there. I would punch to 5400 RPM TO GET ON PLANE LESS THAN A SECOND AND THEY DIDN'T LIKE THAT OR LOADING ON THE TRAILER NO MORE THAN 2 SECONDS.

IMO IT WAS PRETTY QUIET, JUST SENSENITCH PROP NOISE.

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Re: quiet boats

Postby :) » Thu Jan 03, 2013 8:29 am

Someone had pics of a setup on here awhile back. CM boat with a 2 in 2 out down by the radiator and then each side went through a sinlgle in/out muffler. I think running them through the hull with some turndowns helps to
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Re: quiet boats

Postby mscott » Mon Jul 15, 2013 7:49 pm

I say if they're gonna let people get by with riding motorcycles and Harleys with all that noise, then an airboat is no problem.

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Re: quiet boats

Postby fl cracker » Mon Jul 15, 2013 8:10 pm

Mscott, finally somebody with some sense. In been saying that for years!
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Re: quiet boats

Postby Whitebear » Mon Jul 15, 2013 8:15 pm

Loud pipes save lives is the Motorcycle Slogan. It worked for us in Tallahassee.
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Re: quiet boats

Postby fl cracker » Mon Jul 15, 2013 8:30 pm

Bear I agree 100%.
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Re: quiet boats

Postby JB550 » Mon Jul 15, 2013 8:37 pm

Whitebear wrote:Loud pipes save lives is the Motorcycle Slogan. It worked for us in Tallahassee.

really bear? come on that's only because everybody else on the road is quiet. it doesn't work with a airboat. if you use a turbocharged four-cylinder with a good muffler and a NGR blade you could have an extremely quiet boat. too many airboaters think its cool to have a nasty sounding motor. Jmo

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Re: quiet boats

Postby Whitebear » Mon Jul 15, 2013 9:45 pm

I just pointed out, we (motorcycle riders) went through Tallahassee and did it the hard way. I in no way advocate breaking the law, or the spirit of the law.
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Re: quiet boats

Postby pipedog » Mon Jul 15, 2013 9:52 pm

ImageThis might not work with your boat, it made mine quieter but like cntry said DD prop is still loud. I was mainly going for some backpressure to make more tourqe :thumbleft:
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Re: quiet boats

Postby ridinskinnywater » Thu Nov 28, 2013 12:01 am

:fishing any body ever tryed dumping the exhaust out the bottom of the hull on a angle to help quiten engine noise

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Re: quiet boats

Postby Afflicted » Thu Nov 28, 2013 12:29 am

I don't how it makes such a difference but I have magma flows from alumitech. Welded on some simple turn downs and it made a huge difference.. It's less noise when it hits the water or ground first, instead of spewing out the back

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Re: quiet boats

Postby PAINKILLER » Thu Nov 28, 2013 1:08 am

During the exhaust cycle, burnt gases depleted of oxygen are "exhausted" from the combustion chamber. The more difficult it is for the gases to escape, the more "back pressure" there is. The greater the back pressure, the more oxygen depleted gas there is remaining in the chamber during the intake cycle, resulting is less available space for fresh air containing oxygen to support combustion during the combustion cycle. However, if the fuel provided is already fully burnt, there is no significant increase in power if the back pressure is reduced. This is why some people complain that their back pressure reducing new header or large bore exhaust system has not provided an increase in power. In order to optimize an increase in power, the engine needs to be re-tuned to provide additional fuel to take advantage of the additional available oxygen. It all comes down to when the exhaust valve opens n closes
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Re: quiet boats

Postby Dirtman » Thu Nov 28, 2013 10:22 am

ridinskinnywater wrote::fishing any body ever tryed dumping the exhaust out the bottom of the hull on a angle to help quiten engine noise

Have an angled transome on my boat and run the exhaust out very near the waterline when the boat is at rest in deep water and have been told by others that is very quiet. It has two small stainless mufflers on it but not sure who makes them. Run a Q series prop but it is an A/C so I dont know if this helps or not
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Re: quiet boats

Postby N8241 » Tue Feb 04, 2014 6:43 pm

Gents (and Ladies too ! )

After viewing many different designs, from the simple to the most complex, and speaking with my engine builder... who is known to be able to "silence the competition" at sound offs.... here is the list I just ordered. Only thing you don't see is the band clamps, coming from another vendor. I have stainless headers (3") already... and the rest is stainless also as I hope to have no maintenance issues for a LONG TIME. Yeah, stainless is more expensive. about a cooler full of beer and a few gallons of gas more.... will post pix when we get this installed.


Diamond Eye Performance 524526 - Diamond Eye Performance Exhaust Elbows DEP-524526
Elbow, Exhaust, 45 degree Bend, Mandrel-Bent, Stainless Steel, 16-gauge, Natural, 3.00 in. o.d., Each
(Mfr. #: 524526)
Ready to Ship
Ground
$19.97 2 $39.94
Summit Racing SUM-630530 - Summit Racing® Stainless Steel Mufflers SUM-630530
Muffler, 3 in. Inlet/3 in. Outlet, Stainless Steel, Polished, Each
(Mfr. #: SUM-630530)
Ready to Ship
Ground
$72.97 2 $145.94
Walker Exhaust 49032 - Walker Exhaust Flex Tubing WLK-49032
Flex Pipe, Exhaust, Slip-on, Stainless Steel, 3.000 in. Inlet/Outlet Diameter, 10.00 ft. Length, Each
(Mfr. #: 49032)
Ready to Ship
Ground
$92.97 1 $92.97
Summit Racing SUM-694830 - Summit Racing® Muffler Clamps SUM-694830
Exhaust Clamp, U-Bolt, Stainless Steel, Polished, 3.00 in. Diameter, Each
(Mfr. #: SUM-694830)
Ready to Ship
Ground
$11.97 2 $23

Total on this was about $320 bucks. clamps another $50 (4 stainless band clamps)

Im SURE anyone running a car motor on their boat have most of this already. less than $200 bucks folks.... yeah, I'm listening for all the reasons why YOU wouldn't want to cut the noise down. WHAT ?? SORRY, I CANNOT HEAR YOU OVER THAT LOUD A$$ RIG YOUR ON !!

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