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Old 05-21-2019, 07:33 PM   #21
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Good thing were not on this trip with you, I’d be spending all your money (mostly on Libations) to supervise. LOL

Some great info from the fellow TF’ers, as usual.

Cheers gang
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Old 05-22-2019, 12:32 PM   #22
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Is the overhead too low to get some good rise in the hump?
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Old 05-22-2019, 03:49 PM   #23
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The loop will help if the issue is water flooding back from the main exhaust, but I really don't think that's what's happening.


I really think that the same exhaust back pressure that blows the water out of the lift muffler from the genny side, is blowing the water backwards into the genny from the main when the main exhaust goes under water completely from following/quartering seas. The back pressure developed by the main will push equally against the water in the flooded exhaust tube, and against the water in the lift muffler. It will blow the exhaust tube water out the back, and blow the lift muffler water into the generator.
This is the point I was describing with my comment.
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Old 05-22-2019, 04:03 PM   #24
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This is the point I was describing with my comment.
Yes. And that is why a gooseneck is preferable to just a plain hose loop. It has a volume chamber that would have to fill prior to back spilling over.
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Old 05-22-2019, 08:49 PM   #25
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Yes. And that is why a gooseneck is preferable to just a plain hose loop. It has a volume chamber that would have to fill prior to back spilling over.

Just for clarity, where are you proposing the loop? Between the generator and lift muffler, or between the lift muffler and the main engine exhaust tube?
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Old 05-23-2019, 09:21 AM   #26
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Just for clarity, where are you proposing the loop? Between the generator and lift muffler, or between the lift muffler and the main engine exhaust tube?
In between the lift muffler and the main exhaust. But if he has no room for a hose, he has no room for this. Common in sailboats, with low hp diesels deep in the hull.

Look at the flow arrows on the attached drawing.

It would have the same purpose as the hump a hose after the water lock, but allows for volume on the downhill side which maintains the flow velocity on the gen exhaust, while providing a flood volume from the main engine exhaust. Click image for larger version

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Old 05-26-2019, 10:49 AM   #27
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Easiest short term solution is just to keep the genset running in the problematic conditions.
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Old 05-26-2019, 10:55 AM   #28
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Easiest short term solution is just to keep the genset running in the problematic conditions.
Any stretch of the next 2000 + miles for ASD can be problematic. He is on the right track, fix it now so his very nice genset doesn't suffer a sad demise and ruin his trip.
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Old 05-27-2019, 01:02 PM   #29
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No engine or gen manufacturer warrants water entry into the cylinders, regardless of age because if you follow the installation instructions, there's virtually no way water can get in. To me that's very telling, I see violations of exhaust installation guidelines, for propulsion and genset engines, all too often. In many cases they've been that way for years before water actually makes its way into the cylinders.

This drawing is for Northern Lights, but it's pretty much what all genset manufacturers recommend https://www.northern-lights.com/medi...t_drown_me.pdf

While you can have them as a belt and suspenders, I don't like to rely on check valves and flappers to keep water out out of engines/gens because they fail too often.

Also, there is an important difference between siphoning and flooding, this articles details the issue for a genset flooding scenario specifically https://www.proptalk.com/siphoning-vs-flooding.

General details of exhaust systems Exhaust system design - Ocean Navigator - May/June 2018

If you want the exhaust 'long story', you can find a detailed article here http://stevedmarineconsulting.com/wp...s170-FINAL.pdf
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Old 05-27-2019, 05:31 PM   #30
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I was going to post the don't drown me PDF but didn't know how to insert the PDF file into a post. I'm glad someone posted it. Thanks, Steve. That document can also help with main engine issues as well.
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Old 05-29-2019, 05:08 PM   #31
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Is the overhead too low to get some good rise in the hump?
Yep. I was able to get just 1-2 inches.

I did find online the install instructions for my genny. It states if you run the exhaust out the stern install a flapper.

In K-Town and have check valve in hand. Installing tomorrow.

Thanks everyone for the input. Crusty, are you flying up to supervise??
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Old 05-30-2019, 06:39 AM   #32
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If you use a check valve go with the proprietary exhaust Centek or equivalent, a common metal check valve will wear out quickly in exhaust use.
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Old 05-30-2019, 07:28 AM   #33
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Post some pics showing the layout as it is.

I don't like using check valves of any type. Consequences of failure are high, and the do fail. Especially here.

Check valve might be ok for the duration of the trip.
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Old 05-30-2019, 01:54 PM   #34
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Quote:
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If you use a check valve go with the proprietary exhaust Centek or equivalent, a common metal check valve will wear out quickly in exhaust use.
That is the brand I used.

Quote:
Originally Posted by Ski in NC View Post
Post some pics showing the layout as it is.

I don't like using check valves of any type. Consequences of failure are high, and the do fail. Especially here.

Check valve might be ok for the duration of the trip.
Check valve installed. I had to move the lift muffler and I will be putting a 2 x 2 under one edge of it. I will need to be careful not to step on it.

I called Centek to ask if the valve needed before or after the lift muffler. After was recommended.

Top Pic: Shows the run of the exhaust.

Second Pic shows the tip of the check valve.
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IMG_5248.jpg   IMG_5249.jpg  
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Old 05-30-2019, 01:57 PM   #35
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You know with a sawsall and about 15 minutes I could get you all the clearance you could ever want...
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Old 05-30-2019, 02:02 PM   #36
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I did find a light in that corner which of course does not work. Winter list started....
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