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Old 11-05-2021, 20:39   #1
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Wet exhaust routing question?

Im replacing part of my wet exhaust, the first section water separator/muffler.

The hose that comes off of the mixing elbow at the engine originally went directly back and straight down about 10-12" at a 45 degree angle to the original water separator muffler inlet.

Would it be ok to re-route this section of hose to cross the centerline of the boat to the opposite side of the engine at about a 45 degree angle instead of going straight back? This would add about 24" of hose between the mixing elbow and the inlet to the water separator. The length of hose that exits the separator to the outlet on the transom would roughly stay the same, so any backflow water volume should roughly be the same.

I would make sure it drops about the same distance below the water line. The new Vetus muffler has a rotating connection so im guessing its not an issue but want to double check.
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Old 12-05-2021, 04:23   #2
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Re: Wet exhaust routing question?

I can't think of a problem. You're keeping the vertical design the same, and that's what's important. A bit of extra hose isn't going to bother your engine. What led to the re-design?
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Old 12-05-2021, 05:32   #3
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Re: Wet exhaust routing question?

Quote:
Originally Posted by tkeithlu View Post
I can't think of a problem. You're keeping the vertical design the same, and that's what's important. A bit of extra hose isn't going to bother your engine. What led to the re-design?
Indeed.

Except: Note the slope down, from mixing elbo, to waterlock muffler 1/2" per foot of run - which you are increasing].


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Old 12-05-2021, 09:01   #4
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Re: Wet exhaust routing question?

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Originally Posted by tkeithlu View Post
I can't think of a problem. You're keeping the vertical design the same, and that's what's important. A bit of extra hose isn't going to bother your engine. What led to the re-design?
I re-arranged the battery bank behind the engine, pushing it further back so I have direct access to the dripless shaft seal in case of a failure or for burping/maintenance. Also now i have complete access to the back of the engine. I also built a new battery tray to better secure the reserve battery.

Moving the exhaust to the other side opens up the access so i can drop down directly behind the engine easily, if i had to do an emergency repair. Previously the only access to that area was stretching one arm in a really awkward position from a small access panel in the quarter berth. If i kept the exhaust where it was originally, i would have to crawl over it to get into that space.
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Old 12-05-2021, 09:09   #5
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Re: Wet exhaust routing question?

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Originally Posted by GordMay View Post
Indeed.

Except: Note the slope down, from mixing elbo, to waterlock muffler 1/2" per foot of run - which you are increasing].


See also:

"Please Don't Drown Me" ~ Northern Lights
https://www.northern-lights.com/medi...t_drown_me.pdf
Thanks for the links. I'll go check out that Northern Lights link. I spent a fair bit of time on Vetus' website but couldn't specifically find any mention of horrizontal routing, only info related to drop and distances referenced from waterline etc...It sounds like i'll be ok as long as i dont radically change the height of the muffler.
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Old 12-05-2021, 09:29   #6
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Re: Wet exhaust routing question?

Generally keep it as low as possible. The extra hose may be a benefit for more water storage before it enters the engine!
But, if the new muffler location is too far off centerline, then when heeled the water could go into the engine.
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Old 12-05-2021, 09:59   #7
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Re: Wet exhaust routing question?

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Originally Posted by Cheechako View Post
Generally keep it as low as possible. The extra hose may be a benefit for more water storage before it enters the engine!
But, if the new muffler location is too far off centerline, then when heeled the water could go into the engine.
Ok good to know. It will only be about a foot off centerline.
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Old 13-05-2021, 10:54   #8
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Re: Wet exhaust routing question?

Having had seawater in my engine twice - both times through the exhaust system I'm fairly sure - I can advise caution when rerouting the wet exhaust. Both times I had been in 8' - 10' following seas. The first time I thought it was the exhaust outlet being under my counter transom, only 6'' or so above the waterline, so I moved it up onto the transom and raised the swan neck a couple of inches higher. By the second time I could only put it down to the 4' or so of hose between the waterlock and the mixing elbow and that it had a bend lower than the waterlock, maybe allowing water to slosh up the pipe when surfing down steepish waves.
I've fitted a second waterlock at the lowest point but its only a stopgap as the backpressure from two waterlocks affects top revs and I suspect oil consumption. But I can't fit a big enough one at the lowest point to be sure it'll deal with all the water that could be in the system. I really need to raise the injection point or maybe the whole effing engine!
I'm not saying you are in the same position. Just a cautionary tale.
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Old 13-05-2021, 11:44   #9
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Re: Wet exhaust routing question?

Quote:
Originally Posted by Differentroads View Post
Having had seawater in my engine twice - both times through the exhaust system I'm fairly sure - I can advise caution when rerouting the wet exhaust. Both times I had been in 8' - 10' following seas. The first time I thought it was the exhaust outlet being under my counter transom, only 6'' or so above the waterline, so I moved it up onto the transom and raised the swan neck a couple of inches higher. By the second time I could only put it down to the 4' or so of hose between the waterlock and the mixing elbow and that it had a bend lower than the waterlock, maybe allowing water to slosh up the pipe when surfing down steepish waves.
I've fitted a second waterlock at the lowest point but its only a stopgap as the backpressure from two waterlocks affects top revs and I suspect oil consumption. But I can't fit a big enough one at the lowest point to be sure it'll deal with all the water that could be in the system. I really need to raise the injection point or maybe the whole effing engine!
I'm not saying you are in the same position. Just a cautionary tale.

Yes I know how that can happen. A simple fix whilst sailing anyway is to put a valve on the end of the exhaust hose at the transom or hull & shut in following seas. Just got to remember to open it before starting.
I know that problem too
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Old 13-05-2021, 11:47   #10
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Re: Wet exhaust routing question?

Be careful. Having the muffler as low as possible near centerline is most desirable. This keeps the muffler as low as possible on both a port and stbd heel.

If you move the muffler to say, the stbd side, with the hose crossing centerline, you will be in a situation where the muffler is now relatively higher when the boat is heeling to port. If you get into a situation of rough seas and a high degree of port heel angle, the muffler can now dump water down the exhaust hose and directly into the exhaust manifold. It doesn't take much water to do damage.

Imagine the worst case scenario with extremes in heel angle and sea conditions. Both pitching and rolling. These are the parameters that you should use to design your exhaust system.
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Old 13-05-2021, 13:45   #11
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Re: Wet exhaust routing question?

Quote:
Originally Posted by Differentroads View Post
Having had seawater in my engine twice - both times through the exhaust system I'm fairly sure - I can advise caution when rerouting the wet exhaust. Both times I had been in 8' - 10' following seas. The first time I thought it was the exhaust outlet being under my counter transom, only 6'' or so above the waterline, so I moved it up onto the transom and raised the swan neck a couple of inches higher. By the second time I could only put it down to the 4' or so of hose between the waterlock and the mixing elbow and that it had a bend lower than the waterlock, maybe allowing water to slosh up the pipe when surfing down steepish waves.
I've fitted a second waterlock at the lowest point but its only a stopgap as the backpressure from two waterlocks affects top revs and I suspect oil consumption. But I can't fit a big enough one at the lowest point to be sure it'll deal with all the water that could be in the system. I really need to raise the injection point or maybe the whole effing engine!
I'm not saying you are in the same position. Just a cautionary tale.
Thank you. I think im going to install a small bilge pump on the muffler/waterlock winter drain and pump the muffler dry anytime i feel like conditions are bad enough that water could backflow. My exhaust elbow is pretty high and a very steep angle but for $100 for a pump and hose it could end up being a decent investment, especially since i plan to re-power next year with a brand new Beta.
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Old 14-05-2021, 09:53   #12
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Re: Wet exhaust routing question?

Hallo Bad Orca Would you have a moment to send us some photos of the engine room? What is your boat?
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Old 15-05-2021, 00:06   #13
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Re: Wet exhaust routing question?

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Originally Posted by Compass790 View Post
Yes I know how that can happen. A simple fix whilst sailing anyway is to put a valve on the end of the exhaust hose at the transom or hull & shut in following seas. Just got to remember to open it before starting.
I know that problem too
Thanks for the suggestion. I'm sure that I've eliminated that risk by raising the exhaust outlet up the transom.
I'm also in the habit of turning off the seawater valve before turning off the engine in order to reduce the water stored in the exhaust. I can't imagine I'll be lucky getting water out of the engine a third time without serious damage.
When I replaced the original water trap I mused on why it had been modified with an extra inlet about the size of an engine water hose, which had been blocked off. I now realise that somewhere in the boat's 40 year history a previous owner had had a dry exhaust between the engine and waterlock and injected the cooling water at that point. So my problem was probably built in to the engine installation. Its been a bit of a bugger to work out what was going on. But a lightbulb popped on in my head when I worked out where the boat's waterline is in relation to the engine and how that related to the Vetus exhaust installation diagram. So much of it is below the waterline that its no surprise that there can be problems when rolling and pitching.
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Old 15-05-2021, 00:09   #14
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Re: Wet exhaust routing question?

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Originally Posted by BAD ORCA View Post
Thank you. I think im going to install a small bilge pump on the muffler/waterlock winter drain and pump the muffler dry anytime i feel like conditions are bad enough that water could backflow. My exhaust elbow is pretty high and a very steep angle but for $100 for a pump and hose it could end up being a decent investment, especially since i plan to re-power next year with a brand new Beta.
As I mentioned elsewhere, I just turn off the seawater cock before turning off the engine to get the same outcome. I check my impeller regularly. No sign of damage for the few seconds it runs dry
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Old 15-05-2021, 17:46   #15
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Re: Wet exhaust routing question?

Quote:
Originally Posted by FPNC View Post
Be careful. Having the muffler as low as possible near centerline is most desirable. This keeps the muffler as low as possible on both a port and stbd heel.

If you move the muffler to say, the stbd side, with the hose crossing centerline, you will be in a situation where the muffler is now relatively higher when the boat is heeling to port. If you get into a situation of rough seas and a high degree of port heel angle, the muffler can now dump water down the exhaust hose and directly into the exhaust manifold. It doesn't take much water to do damage.

Imagine the worst case scenario with extremes in heel angle and sea conditions. Both pitching and rolling. These are the parameters that you should use to design your exhaust system.
It took a little while for this to sink in. Cheechako mentioned the same. After thinking about it in that perspective im starting to have second thoughts. I could add a little bilge pump to the muffler, which i still may do, but what if it doesn't get all the water out?

As much as i would love to move it, im starting to think it may not be a good idea. if i was heeled over maybe only 30 degrees (guessing) i think the muffler may start to become level or possibly even sjlightly higher than the elbow raw water outlet if i move it to the other side. I think i need to make some careful measurements before deciding.

thanks for all the feedback.
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