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Old 03-02-2020, 09:15   #31
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Re: Do I need a muffler

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Originally Posted by StoneCrab View Post
Unless I am misunderstanding some of these posts, I am very surprised to learn that there are boats out there running dry exhaust through rubber hoses.

That would be incredibly hot and seems unsafe.

Would still be a wet exhaust with raw water mixed into exhaust at the mixing elbow - nothing changes. What does change is the lift muffler is removed so the water-cooled exhaust exits directly. Exhaust gases can reach 1000-degrees F and would make short order of the rubber and fiberglass components if not cooled.
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Old 03-02-2020, 09:23   #32
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Re: Do I need a muffler

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Originally Posted by captlloyd View Post
You don’t need to run a dry exhaust through any rubber hoses. You need to be aware that if your piping is going to run near or through bulkheads, decks or any other part of a boat that is wood or fiberglass that you need to make sure it is either insulated or the temperature at that point is not excessive. A heat measuring device would be employed at any critical point. Of course my boat was steel so no issue. But many commercial fishing boats run dry stacks, even smaller ones. It sure simplifies things.
Dry-stack exhausts are difficult on recreational boats. The engine itself still needs to be cooled, so a keel-cooler is fitted on the exterior of the vessel. This needs cleaning and zincs. Further, when the stack goes up through the salon, needs to evacuate a lot of heat, which requires relatively large blowers to suck air up through engine room.

Temp measuring device is a good idea on wet exhaust too. Traditional alarm on the engine doesn't trigger until it is really hot, which may be too late. Steve d'Antonio mentions this type in one of his articles. Simply zip-tie to the exhaust after the mixing elbow. If it reaches 165-degrees, triggers an alarm much more quickly. Under $100 and pretty good insurance.

Wet Exhaust Temperature Alarm by Borel Manufacturing Inc.
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Old 03-02-2020, 10:06   #33
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Re: Do I need a muffler

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Originally Posted by mvweebles View Post
Would still be a wet exhaust with raw water mixed into exhaust at the mixing elbow - nothing changes. What does change is the lift muffler is removed so the water-cooled exhaust exits directly. Exhaust gases can reach 1000-degrees F and would make short order of the rubber and fiberglass components if not cooled.
No, not using a water cooled manifold or elbow or rubber hoses at all. I Keel cooled my engine and also the trans cooler but that was it. All steel exhaust system. Turbo charged too. As I said it was a steel boat. However I also stated that the Kabota that I owned seemed to run very cool with very little heat being radiated off of the exhaust. Just saying if it were me I would experiment with that engine and exhaust and see if it would be feasible to run dry exhaust.
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Old 03-02-2020, 10:39   #34
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Re: Do I need a muffler

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Originally Posted by captlloyd View Post
No, not using a water cooled manifold or elbow or rubber hoses at all. I Keel cooled my engine and also the trans cooler but that was it. All steel exhaust system. Turbo charged too. As I said it was a steel boat. However I also stated that the Kabota that I owned seemed to run very cool with very little heat being radiated off of the exhaust. Just saying if it were me I would experiment with that engine and exhaust and see if it would be feasible to run dry exhaust.

Apologies if I misunderstood - I thought the statement was that by removing the lift-muffler, the system was run as a dry-exhaust with rubber/fiberglass fittings.



To run a dry exhaust, would need to run a steel exhaust all the way back (and on a sailboat, it really needs to go to the stern vs the side due to heeling angles). If the boat is fiberglass, would probably need some sort of thimble where it passes through the hull to prevent heat damage to the fiberglass, though who knows - maybe your experience with cool-running Kubota is normal.
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Old 03-02-2020, 11:10   #35
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Re: Do I need a muffler

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Originally Posted by mvweebles View Post
Apologies if I misunderstood - I thought the statement was that by removing the lift-muffler, the system was run as a dry-exhaust with rubber/fiberglass fittings.



To run a dry exhaust, would need to run a steel exhaust all the way back (and on a sailboat, it really needs to go to the stern vs the side due to heeling angles). If the boat is fiberglass, would probably need some sort of thimble where it passes through the hull to prevent heat damage to the fiberglass, though who knows - maybe your experience with cool-running Kubota is normal.
Yes, anything flammable needs protection. In the world of hot rods they use a wrap that looks like heavy woven cloth but is surprisingly made from lava rock and contains heat considerably. Also this thread has got me thinking about what would happen if you welded in a scavenger tube to your system which would cause your exhaust to suck in cool air thus lowering temperatures. I realize these things are trial and error and your idea of a permanent temperature monitor is a very good idea.
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Old 03-02-2020, 11:17   #36
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Re: Do I need a muffler

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Originally Posted by StoneCrab View Post
Unless I am misunderstanding some of these posts, I am very surprised to learn that there are boats out there running dry exhaust through rubber hoses.

That would be incredibly hot and seems unsafe.
I think your misunderstanding the posts
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Old 03-02-2020, 11:31   #37
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Re: Do I need a muffler

I wouldn't worry about a muffler from a noise standpoint, but water retainment is important. There are often other , hard to get to places, that a muffler can be put in to use up unused space. Or even two smaller mufflers. Potentially a lot of water in that hose.
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