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I have a 86 Bahner 21' with a Berkeley jet and BBC 454. Just got the engine back from a rebuild and would like to install an exhaust diverter system while I'm putting it back in. I like to hear my radio when I'm idling around the marina. The above the water line transom exhaust is pretty loud.

I purchased some used, solenoid actuated, exhaust diverter valves that are kind of a Y configuration. Coming off my logs and snails is a 4" exhaust hose that heads out the back transom above the water line to the exhaust tips with flaps. I have enough room to splice in the diverters and run a 3" hose below the boat but I'm concerned about that and don't want my boat on the bottom of the river or blow my motor by pumping it full of water. Also wondering what tips to use if this isn't a stupid idea. Something about drilling 3" holes in the bottom of the boat doesn't feel right.

Is this a bad idea? Anyone have any experience with this?


Don
 

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You can get exhaust tips with internal flappers to keep the water out below the water line. I've never heard of anyone doing this and sounds like alot of work for just trying to make their boat quieter. My 2 cents: look into some baffles that slip into your exhaust tips or install a louder stereo LOL
 

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You can replace tips with marine mufflers.

Sent from my SCH-I545 using Tapatalk 4
 

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Check out some of the aluminum jet fishing boats.

Some of those have turned down exhaust ports that direct the exhaust below the surface. They are very quiet at idle.
 

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Sounds like a bad idea to me. Why not just lower your exhaust outlets you have now to below the water line at idle?
 

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Damn, most guys would like to get their tips out of the water and you wanna get em in. :)eh:)
 

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Don't do it. The vibrations from the exhaust coming out under the boat will be so bad and loud that you won't hear the stereo anyway. Bad Idea! Have seen it done with poor results.
 

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I've seen the tips extended downward so they're below the water line off-plane. On-plane they're above the water line.

My CV23 has factory below the water line tips off-plane. Sort-of a passive switchable exhaust. Don't do it. If you would lose cooling water for some reason and burned through an exhaust hose, she's going down. Unless your bilge pump can handle the amount of water pouring in from a 3"+ hose.
 

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I see what you're getting at, and I wanted to do something similar. Have one set of tips that are un-muffled and loud with another set that had mufflers. Ultimately, there is not really a cost effective or reliable way of doing this if you have water flowing through your exhaust.

I wound up with a set of Gibson mufflers that work well. You might could do clamp on mufflers, and almost accomplish what you want.
 
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