Quieter Exhaust options
 

Hello all! New member here, been skimming and scanning the forums for a few months trying to learn up a little bit.. The focus up until now has been on finding our home on the water and we close on that tomorrow, so time to focus on getting a boat!


We are going to be on a larger fresh water lake in AL. This lake sees significant wakeboat traffic and gets pretty choppy, we rented a bow rider and even on a not very busy day it just pounded once up on plane, no amount of changing attack angle to waves, trim, etc would help. I spent weekends growing up in the 80's on boats and know how well "offshore" boats with proper deadrise will handle these sort of conditions, plus they are just beautiful! So I have been keeping my eyes out for something like that. Older Formulas, Scarabs, Bajas, Cobalts, Mirages etc. One big probem. Alabama has noise restrictions and the way I read AL law, Captains Call style systems are not allowed either. This lake itself is quiet which was a big draw, and last thing I want is to ruin that or stir up the neighbors if I want to leave early in the morning and I know marine patrol is active on the lake and do not want to deal with that hassle either.


So I need to find out more about Thru prop exhaust or other options to keep the noise down! Are there other options maybe less expensive to quiet things down? I watched a youtube and the person had a Formula with an underwater exhaust option?


So far every boat in the style I am looking at has had thru hull exhaust. Usually a 350 or 454 engine, most boats have had Bravo 3 outdrives, a couple had 1's. What exactly is needed to convert on of these to exhaust thru the outdrive? It looks like "just" a horseshoe shaped manifold for lack of better term that comes off the thru transom outdrive unit and then hose attaches that to the risers? Where to find that sort of item?


Any and all help, tips, guidance is much appreciated!

What is the db limit law?
lots of tailpipe muffler set ups are pretty quiet. Formula’s silent thunder exhaust (inside theswim platform) is pretty quiet . .

86dB @ 50ft
Full noise regs:

• The exhaust of every internal combustion engine used on any vessel shall be effectively muffled by equipment so constructed and used as to muffle the noise of the exhaust in a reasonable manner. It is unlawful for any person to operate or give permission to operate any vessel powered by an engine or outboard motor in such a manner as to exceed a noise level of 86 decibels measured at a minimum distance of 15.2 meters (50 feet) from the vessel. The use of cutouts is prohibited, except for vessels competing in a regatta or official boat race, and for such vessels while on trial runs.

The horseshoe manifold you mentioned does indeed turn it down through the drive. Just fyi you will have to pull motor to install that, you’ll need new tails, silent choice actuators, etc…..

turndowns help at idle but are loud on plane.

im least qualified to answer this but appreciate you trying to be a good neighbor on those smaller lakes.

Hey I appreciate any and all feedback and info! Yeah part of the nice thing about this lake is the quiet. Based on some of my reading here on offshore, the performance loss is minimal and I am not racing, I will take the fast, comfortable and quiet ride.

I am pretty sure the way I read the regs the silent choice actuators will not be an option. Betting they would consider that a bypass. Did more digging, sounds like that manifold is called a Y pipe lots of them on Ebay and other places for prices that do not break the bank.. Like usual I am going one direction while everyone else is going the other. I will take advantage and take their stock discards...

What do you mean by new tails? you mean tailpipes out the transom? I would pull whatever is on the boat and plug/cap the openings in the transom as part of the conversion to thru prop. There is one boat I am keeping an eye on that needs new risers and already has the old ones off. Perfect time to pull the motor and swap the exhaust setup out......

Yes, I meant new tails pipes if you were switching to a switchable/captains choice style but if you’re going the y-pipe route you’re right - need to fill the holes, etc.

I wouldn’t pay much for y-pipes. I think most people give them away. Hell, I couldn’t give mine away so eventually I just put them in the trash!!

Boats with stock twin 350's or 454's and external mufflers should have no issue and will be below the 86db limit.

Ty. Any chance there is a brand/model you would recommend for external mufflers?

Corsa is a good name in marine exhaust. https://corsamarine.com/collections/silencers

Mine have swirl things in exhuast
really only can hear them at idle
Nice rumble and well below 84
At high speed you csn hear the air coming in
At moderate throttle its pretty tame
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