Exhaust Flapper

johna

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Do you recommend installing a rubber exhaust flapper on your wet exhaust pipe thru the transom? Where can you get one for an 8 inch O.D. pipe? Thanks for any suggestions.
 

F/V First Team

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I don't recommend flappers, but if you're dead set on one I would suggest getting one fabricated up at your local machine shop out of stainless that you can basically just clamp on. I haven't seen any rubber ones for 8" yet.
 

MASTERENEGADE

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Had a DE, now 24' Privateer
Travis why dont you recommend one. I have a 6" rubber one on my exhaust as we speak for the last 10 yrs of owner ship.
 

johna

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I was told if you use a flapper it reduces the chance of getting water in your engine when backing down or in following seas. Why dont you recommned them?
 

F/V First Team

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Guess I don't like cleaning the transom from the puffs of exhaust that burble out. I tend to dump my exhaust out on the corner so it's not a straight shot up the line.

I currently have dual pipes out the back and I have no flappers on them. Doesn't seem to bother.
 

steveinak

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Guess I don't like cleaning the transom from the puffs of exhaust that burble out. I tend to dump my exhaust out on the corner so it's not a straight shot up the line.

I currently have dual pipes out the back and I have no flappers on them. Doesn't seem to bother.

ya got a black boat :lol:
 
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johna. We just had an 8" hinged flapper cast in bronze. We should be installing it this weekend. I will take a couple of pictures. If you want, I can have another cast and machined.
 

Old Mud

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Blexter

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Another question I was concerned with....
I upgraded my 6" pipe to an 8" and have a slug tube. Even with the tube, I worried about backing down 'with that big hole in the back of the boat' so I have a homemade flapper out of fiberglass. The hinge is glassed into the flapper and bent to fit into small holes drilled into the 1" pipe extention in the transom. If it works ..... great. If not, no problem, it can be removed in 10 seconds.
I will take pictures if you need them
 
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Brooksie

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I don't think flappers are much help backing down because you are powering and have pleanty of exhaust gas coming out to keep the water at bay.

Anchoring in a seaway is a different story. Here the exhaust opening picks up a charge of water and rolls it down the exhaust line as the boat pitches down by the bow. However in this case, as the stern drops into a wave the flapper is pushed open by the water making it useless. Actually it would be more effective if it were installed upside down, The answer here is to have the flapper INSIDE the pipe so it won't me pushed open as the transom falls.
 

Duke

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m williams

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I have the underwater. Exhaust on my bhm 28. It's the salisbury exhaust. The one you see used on the general marine 26
 

chortle

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I have twin 4" exhausts, totally open, very little rise to the risers, been that way for 42 years, apparently no problems as the engine is still belching along but no sane person today would recommend doing this. I would recommend looking at the rise between the exhaust at the transom and the spillover at the engine and make sure that it has the recommended 12" or more, a surge tube and/or an inline axial water drop muffler would likely be good choices to add to mitigate backflow. Can't see why the rubber flap couldn't be of some help, "most of the time," pretty good bang for the buck as part of the system. I underline system as that is what is important, how the whole system works together. I would not sink and engine exhaust 12" below the waterline and expect the flap to keep it safe. Neither would any one of the other ideas alone be bullet proof, this is a good place for redundancy, several pieces that each alone are good and complementary, and all together, much better.

true waterline.jpg
 

Dr. Chip

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Master..
I completely agree. Seems to be a local favorite.. MBrooks resonates with us NYers
 


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