Best Location for Genset Exhaust?

[Madehn]

i am in the process of putting a new Gennie into my boat- i have a choice of running the exhaust 25 feet to exit under the stern- this is how the old generator was plumbed. It is possible to do it that way again but it is a real beast running the 2" hose through. Also the outlet is right at/slightly below the water line and is not visible. It is an option to simply go our the starboard side of the hull without all the hassle of running the long distance hose. i could place the outlet 6 inches above the water line and it would be possible to see water flow etc. i understand that both ways need a loop that rises up to deck level at least. i would like to hear pros and cons of both methods. Thanks in advance. Generator is a 10kw westerbeke if it makes any difference.

[Oceansailor]

Shorter is always better as the backpressure is less. But I think the 10kw Westerbeke will be able to handle 25 feet exhaust.

[sailorboy1]

When I installed my generator I looked into the whole thing. There are some great installation articles if you do a web search.

If you do the old routing to the stern be sure there's a loop so that the line can't back flood on a pooping wave.

A big advantage of an above the water line installation is that you can check there is water flow.

[svHyLyte]

Assuming you'll primarily use that generator at anchor, you'll want the exhaust as far aft as possible so to avoid dealing with fumes from the exhaust discharge which can be a major headache if not a health hazard. Any job worth doing, is worth doing right, even though a bit more effort may be required.

FWIW...

[Terra Nova]

Originally Posted by Madehn

...i understand that both ways need a loop that rises up to deck level at least...

The loop should always remain at least 18" above the discharge port. But the problem with a side exhaust is that it can sometimes create a large volume of water trying to force itself back to the engine when the boat is heeled.

[Pelagic]

Before deciding, consider a Gas/water Separator for your Gen.
https://citimarinestore.com/en/north...00-32007-.html

They make the Gen. whisper quiet and generally favor a short run off the Stbd side.
Mine is set up that way and the dry gas exhaust which exits about 3 feet above the waterline and aft of seating, is swept away nicely by even the lightest breeze hitting the hull.

Sometimes with stern positioned exhaust, you can get a bit of a vortex in light conditions, that sweeps the exhaust back in.

[captainjay]

Originally Posted by Pelagic

Before deciding, consider a Gas/water Separator for your Gen.
https://citimarinestore.com/en/north...00-32007-.html

They make the Gen. whisper quiet and generally favor a short run off the Stbd side.
Mine is set up that way and the dry gas exhaust which exits about 3 feet above the waterline and aft of seating, is swept away nicely by even the lightest breeze hitting the hull.

Sometimes with stern positioned exhaust, you can get a bit of a vortex in light conditions, that sweeps the exhaust back in.

Take it out the side and separate the exhaust water. A shorter run will be better for the genset. Less likely to ingest water and with a seperator it will make less noise.

Keeping a proper drop on a long exhaust can be difficult.

"Most generator and engine manufacturers call for a specific minimum “drop” in the exhaust, often 12″ (305mm), from the exhaust elbow or spray ring to the muffler, with a continuous downhill slope of ½″ per foot (42mm/m). Probably the most common violations I encounter are wet-exhaust hoses that form a lazy-U shape, dropping from the injected elbow to the bottom of the generator sound enclosure, exiting the enclosure, and then traveling upward to a waterlift muffler. Depending upon the generator’s orientation, water trapped in this section of hose can—when the vessel rolls, heels, or pitches—sluice up and into the exhaust manifold, and then to the open exhaust valves, and finally into the cylinders."

https://www.proboat.com/2011/03/generators-done-right/

https://www.vetus.com/en/exhaust-sys...separator.html

[LakeSuperior]

Our Mason 44 was equipped with side exhaust. Not good. The loop was big but heeled or with sea from the side overwhelmed the loop. That is even with a rubber flap seal. Salt water destroyed the head. Route to the stern with all cost.