Wet Exhaust thoughts

Designs for inboard or outboard power

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CaptBob
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Wet Exhaust thoughts

Post by CaptBob » Fri Sep 05, 2014 10:22 am

Hello,
I've got a question for you boat builders out there.
What are your thoughts on a wet exhaust system that actually directs the exhaust under water, and not at the water line.
I know it has its advantages to noise and fumes, but what are the disadvantages?

The reason I am asking, is because on my double eagle, I have had some people say that they are getting the "station wagon" effect and sometimes breathing in excessive fumes with wind direction.
A simple fix would be to put a 90 degree elbow on the exhaust and direct it under water, or hand out gas masks to the passengers riding in the back. :lol: :lol:

Any suggestions or ideas?

Thanks!
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My current exhaust set up
2000 Glen-L Double Eagle "Fan-Sea"

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Bill Edmundson
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Re: Wet Exhaust thoughts

Post by Bill Edmundson » Fri Sep 05, 2014 1:19 pm

CaptBob

I suggest that you make yourself happy. :) They are not paying or working :!:

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

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CaptBob
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Re: Wet Exhaust thoughts

Post by CaptBob » Fri Sep 05, 2014 1:25 pm

Very true Bill!
Maybe I just need to find new passengers! haha :lol: :lol:
2000 Glen-L Double Eagle "Fan-Sea"

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Mr Hot Rod
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Re: Wet Exhaust thoughts

Post by Mr Hot Rod » Fri Sep 05, 2014 1:54 pm

You may want to relocate your transom outlets away from the centerline :
Inboard Motor Installations wrote: On transom sterned boats, the outlet should be located well away from the centerline so that there will be less of a tendency for the fumes to come back abord the boat

Source : Inboard Motor Installations by Glen L. Witt and Ken Hankinson, Page 173
In Canada :
In USA :
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CaptBob
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Re: Wet Exhaust thoughts

Post by CaptBob » Tue Jan 06, 2015 11:55 am

Bill Edmundson wrote:CaptBob

I suggest that you make yourself happy. :) They are not paying or working :!:

Bill
Hey Bill,
I am ready to take on the modification of the exhaust exit.
Re configuring the exhaust pipes to exit further away from the center line is a bit more modification than I want to do, so based on the sketch below, would adding a 90 degree elbow about 3" below the water line be an issue?
Also, should the tip be cut at a 45 degree angle as shown in the sketch, or the other way?
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FullSizeRender.jpg
2000 Glen-L Double Eagle "Fan-Sea"

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Bill Edmundson
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Re: Wet Exhaust thoughts

Post by Bill Edmundson » Tue Jan 06, 2015 2:41 pm

Sorry. I'm just not qualified to answer that. Engine back pressure, exhaust flow and backflow. I don't know.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

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CaptBob
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Re: Wet Exhaust thoughts

Post by CaptBob » Tue Jan 06, 2015 2:44 pm

No problem Bill.
Hopefully someone else will chime in that has done this before, or has some input.

Thank you!
2000 Glen-L Double Eagle "Fan-Sea"

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Bill Edmundson
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Re: Wet Exhaust thoughts

Post by Bill Edmundson » Tue Jan 06, 2015 2:48 pm

Paul Kane, Mr. Hot Rod, might have some good input for you.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

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kens
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Re: Wet Exhaust thoughts

Post by kens » Tue Jan 06, 2015 5:23 pm

There are vendors that make such an exhaust exit.
I have seen them in catalogs, but never gave them a closer look.
Maybe Buck Algonquin?
Perko?
Attwood?
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

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CaptBob
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Re: Wet Exhaust thoughts

Post by CaptBob » Tue Jan 06, 2015 5:27 pm

I'll have to check. If not, I might just have someone fabricate an elbow and pipe for me to go about 3-4" under the water line.
2000 Glen-L Double Eagle "Fan-Sea"

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kens
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Re: Wet Exhaust thoughts

Post by kens » Tue Jan 06, 2015 5:28 pm

I cant help but wonder why your getting these fumes, and I an not.
I know you got a V8, but, I am not getting any fumes like that, none, notta, zip, zilch.
Both of us got a Double Eagle with exhaust exit close to centerline.
What can be so different?
Oak is over rated, everything about it takes extra time; then it warps, splits or checks !!! :roll:

Cyclone
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Re: Wet Exhaust thoughts

Post by Cyclone » Tue Jan 06, 2015 6:43 pm

Just an idea. I see you have a swim platform on your boat and I was thinking about whether the exhaust is coming up through the openings between the pieces of wood that make up the platform, and also through the space between the transom and the platform. Perhaps you could mount a piece lexan (clear plastic) or plexiglass on the underside of the swim platform. This type of material might available at places like Home Depot or Lowes. You could leave a small gap between this plastic and the transom and then put a piece of weather striping in this gap to stop the exhaust from going through there. I would use a few stainless steel washers between the plastic and the platform so that any water that collects on the plastic would not stay in contact with the wood. Mount with the plastic with stainless steel screws to the underside of the platform. The exhaust would have to flow to either the side, or to the end, of the platform and at this point I think it less likely to find its way to the passengers.

Before you spend time and money on this idea, I would suggest that you test the concept by using cardboard and duct tape to cover the top of the swim platform and to seal it up to the transom. Then take some people out for a test to see if they think it improves the situation.

Trackhappy
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Re: Wet Exhaust thoughts

Post by Trackhappy » Tue Jan 06, 2015 7:00 pm

That's a great idea Cyclone. The other thought is to take the exhausts sideways with an elbow and piece of pipe then maybe a 45 on the end so as to effectively move them outboard but still above the waterline and therefore avoid any back pressure issues or siphoning issues. You could later add a horizontal board above this setup to hide and protect it if it proved to work well.
By the time I have built a boat, I'll be ready to build a boat....

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Barra
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Re: Wet Exhaust thoughts

Post by Barra » Tue Jan 06, 2015 9:54 pm

We used to do underwater exhausts on ferries and yachts, but always fitted a bypass above waterline for when the vessel wasn't moving due to back pressure issues.

We mainly did it for noise and aesthetic reasons not for fumes and it was on larger vessels (120ft - 300ft).

They are tricky do do correctly (one company I worked for wouldn't go near them) so if you've got other options I would start there...

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hoodman
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Re: Wet Exhaust thoughts

Post by hoodman » Wed Jan 07, 2015 9:13 am

Is your motor maybe running a bit rich? Maybe you just need a carb adjustment or something.
Matt

Building a Geronimo......!
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