Quiet My Boat

A discussion on ways to reduce it.
TSnake
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Quiet My Boat

Postby TSnake » Tue Apr 13, 2010 11:19 am

I’ve got a 454 turning a 78” Powershift through a 1.7:1 Stinger. Exhaust is headers to flex-pipe to mufflers. Boat is a 15’ Rivermaster. I use it for riding & gator hunting. No racing or trying to climb Mt. Everest for me. I’d like to quiet this beast down a bit. As always, money is an issue. Looking for suggestions for best bang for buck. If I rig up an exhaust crossover system would anyone tell a difference as long as I’m turning that gear/prop combo? Any other suggestions? Anti's are busy around here. Sure would like to disarm them.
Micanopy, FL
15' Hoffman Rivermaster
454 Stinger 2.68 3-blade S-series

gizzardgitter
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Re: Quiet My Boat

Postby gizzardgitter » Tue Apr 13, 2010 11:49 am

hey man,,
I go out of horseshoe alot mullet fishin
and lots of the peeps down there piss n moan
about airboats to loud big motors ,, Ha,,
im runnin same motor headers flex mufflers.
ridin on it its quiet to me and the wife.
so i stood on the bank other day.
let wife take it on a short run. told her
to stand in it. from behind i couldn't even
hear the motor was all prop noise
GizzardGitter

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Waterthunder
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Re: Quiet My Boat

Postby Waterthunder » Tue Apr 13, 2010 11:58 am

Hate to tell you this but slowing down the prop is the only way. More ratio and a blade that pushes down low like a Sensenich S blade or a Maximus both with a 2.68 or higher ratio! Good automotive mufflers also help but that's the only changes that will make a big difference.
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done."

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roberti53
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Re: Quiet My Boat

Postby roberti53 » Tue Apr 13, 2010 1:16 pm

Waterthunder wrote:Hate to tell you this but slowing down the prop is the only way. More ratio and a blade that pushes down low like a Sensenich S blade or a Maximus both with a 2.68 or higher ratio! Good automotive mufflers also help but that's the only changes that will make a big difference.


That's why I went this route.
Try to keep them off my back. (not sure anything will please them)
I went with the 3 blade S and 2.68 box.

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cowboy
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Re: Quiet My Boat

Postby cowboy » Tue Apr 13, 2010 1:45 pm

I have found that I can run a very loud boat in areas where there are very few people.
Almost nobody can hear my boat.

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Re: Quiet My Boat

Postby Ruagatr » Tue Apr 13, 2010 2:58 pm

@ Cowboy...LMAO!

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plumcrazy
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Re: Quiet My Boat

Postby plumcrazy » Tue Apr 13, 2010 3:43 pm

i got car muff on my ac boat but im like cowboy stay away from people and we aint got no troubles , but its gettin harder every day :evil: but then i remember when i would hide from another airboat too 8)

cntry141iq
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Re: Quiet My Boat

Postby cntry141iq » Tue Apr 13, 2010 8:16 pm

Carquest auto parts #5571 mufflers ... exhaust turndowns outside the transom ... 2.68 box and three blade or four blade swept tip prop preferablly a sens superwide ... but whatta I know LOL
Don't waste your time ... it is the only thing you can't get more of
.. if it accidentally looks like I gave advice please ignore it .. and notify me immediately

TSnake
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Re: Quiet My Boat

Postby TSnake » Tue Apr 13, 2010 11:31 pm

Cntry, thanks for the recipe! Do you run a crossover exhaust or duals? Now for the prop, how do I figure out the how to get there from here? I’m guessing that changing the ratio in a Stinger isn’t an option? Love the idea of turning a 3-blade Sensenich S series through a 2.68 but I don’t know if that’s too much for this engine. Maybe a 2-blade would be better? I have no idea how many horses my 454 is making but I love the way it performs now and it sure would be great to run without earmuffs and still be able to hear at the end of the day. So, if I commit to a 2.68, how do I figure out how many blades is right for my boat?
Micanopy, FL
15' Hoffman Rivermaster
454 Stinger 2.68 3-blade S-series

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Waterthunder
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Re: Quiet My Boat

Postby Waterthunder » Wed Apr 14, 2010 8:55 am

You should be able to turn a 3 blade S with a 2.68 with a decent 454 BBC. Try not to run a 2 blade S they don't work as good as a 3 blade and with only two blades being so wide the tend to vibrate a bunch. I ran S blades with a 2.68 and cheap Summit stainless mufflers with down turns pointed at the center of the transom. I had the quietest boat by far at the sound competition that FWC and a university held. I still have airboaters giving me hell over that. You don't even need to turn an S blade 2,000RPM's they make all their thrust down low!
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done."

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TSnake
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Re: Quiet My Boat

Postby TSnake » Wed Apr 14, 2010 2:11 pm

Thanks Dave! I read about the sound competition in detail. That’s what I’m looking to make. A ‘swoosh’ boat where I can talk with the passenger and hopefully doing it without sacrificing performance. Just trying to figure out how to get there from here and sucking up as much info as possible from those that have already been down this road. For the competition did you run dual exhaust, or some type of crossover system?
Micanopy, FL
15' Hoffman Rivermaster
454 Stinger 2.68 3-blade S-series

cntry141iq
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Re: Quiet My Boat

Postby cntry141iq » Wed Apr 14, 2010 11:41 pm

Dan the airboat man can tell ya all about what your options are for your stinger box. send him a pm or call him his number is all over this forum. I ran a x pipe and duals they make a muffler with two in and two out which would give ya plenty of tail pipe length which will cut your sound big time. just gotta slow that prop down with a different gear and of course a prop made to turn slow and make thrust at slow speed. nobody wears ear muffs on any of the boats I run. and they were big barges most of the time in the past so my engine had to work at it.
Don't waste your time ... it is the only thing you can't get more of
.. if it accidentally looks like I gave advice please ignore it .. and notify me immediately

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Waterthunder
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Re: Quiet My Boat

Postby Waterthunder » Thu Apr 15, 2010 9:19 am

I just ran a very simple common dual exhaust, I don't like to run cross overs in airboats.
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done."

http://waterthunder.com/
321-508-5316

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Waterthunder
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Re: Quiet My Boat

Postby Waterthunder » Thu Apr 15, 2010 9:24 am

Here is a pic of exactly as it was for the sound competition. It had a set of cheap stainless Summit mufflers pn#630530 $72 EACH and a set of down turns. I threw it all together the day before the sound test. A buddy had a db meter and we ran it and turned the down turns until it was the quietest. It was real cheap real simple and took no time to do.


Image
THE PROOF IS IN THE PROP!

"If you copy someone you will only achieve what has already been done."

http://waterthunder.com/
321-508-5316

rost495
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Re: Quiet My Boat

Postby rost495 » Wed Apr 21, 2010 9:43 pm

Not to be too picky, but turn downs are probably an optical illusion, you said pointed at center of transom, IE either at 90s pointed at each other, or 45s to the low center of transom.

Those on the pic look to be pointed 90 straight down to the water?

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Re: Quiet My Boat

Postby warrior-p » Thu Apr 22, 2010 10:36 am

I just finished my new airboat with a ZZ502, 2.68 Stinger softdrive and 3" 24" long (longest in 3") Magnaflows on my boat with no turndowns. It is super quiet. The turndowns will definately help. I took fannman's advise on the forum to make my boat as quiet as possible and it has already paid off. We use my partners high performance, louder boat when we are not fishing around houses and mine when we want to be as quiet as possible.
18 x 8 TEXOMA AIRBOAT, ZZ540 engine, 2.38 BALLISTIC DRIVE and an 82" 4 blade Whirlwind Whispertip EX prop

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BenBad
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Re: Quiet My Boat

Postby BenBad » Sun May 02, 2010 11:38 pm

I just added spark arresters/baffles from http://www.dansperformanceparts.com/bug ... %20acc.htm to my boat and got to take it out today for the first time. I have a very short exhaust system and they helped greatly. Next week I will get my new Sensenich Q prop and see if this helps over the 72x34 paddle and the 3 blade IVOprop that I have been using.

I like WaterThunders setup. My exhaust is just a little shorter than his in the photo.

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SwampMatt
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Re: Quiet My Boat

Postby SwampMatt » Mon May 03, 2010 7:25 am

Greg (SCAC president) wrapped his headers in fiberglass. He says this was to further cut down the sound. I'm not sure if this works or not - His boat is pretty dang quiet though. I'm not sure what kind of mufflers he's got. I'd imagine that flex pipe leaks some sound too. Can that be fiberglass wrapped too?

And cntry has a point - total length. Look at a car or truck - they've got at least 10 feet of pipe/cans in their system. And most cars and trucks (with the factory system) are pretty quiet when on the throttle.

Waterthunder had the most quiet boat in the world at that sound competition (still, CONGRATS Dave!) But the only reason he won is because cntry did not enter his boat! LOL

Key to a quiet boat: well muffled motor, and a slow turning prop. (use a high gear ratio to get the slower prop) Just like what waterthunder and cntry are saying.

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Re: Quiet My Boat

Postby 80 panther » Thu Jun 03, 2010 3:44 pm

Has anyone watch the video on the new NGH prop? it sounded pretty quiet to me. :idea:

cntry141iq
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Re: Quiet My Boat

Postby cntry141iq » Mon Jun 07, 2010 10:59 am

only a slow turning prop is gonna be quiet ... once you break mach 0.5 all bets are off as far as sound goes.
Don't waste your time ... it is the only thing you can't get more of
.. if it accidentally looks like I gave advice please ignore it .. and notify me immediately


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