Generator Exhaust Location?

I am installing a (new to me) 4kw generator driven by a 2 cylinder Yanmar engine.

I plan on installing it centerline aft of the engine close to the bulkhead that separates the engine compartment from the lazerette.

It has a 2" exhaust outlet and I will be using a water lift muffler.

Any pros and cons on just taking the short route out the side of the hull, or should I go aft and out the transom under the swimplatform like the main engine?

JohnP

* I have a setup like you are talking about. The plus is the exhaust is carried away down the side of the boat, unlike several friends whose gen. exhaust exits the stern and loops right back into the rear of the boat. The down is when rafting no one wants to be on that side of the boat. Another plus is a shorter run. I have never had a problem with exhaust staining the side of the boat either.

Typically the exhaust exits via the stern for several reasons, fumes at dock, rafting, etc. but most important is the huge preasure of beam seas wanting to force water back into the engine.

John ihad the same set upon my eagle and i ran it out the side,but i used a* lift muffler and* never had* a problem of water getting in the exaust and i was very big beam seas* ,many times,i also put a valve on the inside of the hull* just in case i ran aground and the boat layed over i could close the valve so that no* water would get back in to the engine.

JohnP wrote:
Any pros and cons on just taking the short route out the side of the hull, or should I go aft and out the transom under the swimplatform like the main engine?

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Don't' know about pros and cons but a good number of the boats I see have the generator exhaust coming out one side or the other.** Others have it exiting under the swimstep. *

Our GB's Jurassic MDJE exits via a fiberglass muffler through an exhaust opening a few inches above the waterline in*the middle*(more or less) of the engine room on the starboard side.** Out the side seems to be a pretty typical setup for GBs, at least the older ones.* We've had no problems with the exhaust in this position.* We have no reason to run the generator when we're underway so can't speak to the fume issue in that regard.* But regardless of the wind we never get any exhaust fumes in the boat when we're running the generator on a mooring, at anchor, or against a dock (we usually tie up on the starboard side since that's where the main cabin door is).

Our generator exhausts at the mid-point of the port side, similar to Marin's.* The way I see it, at anchor we are facing the wind.* Therefore, the exhaust is swept back away from the boat as opposed to swirling around the transom, thereby causing an ugly environment for those sitting in the cockpit.* Just a thought.

Ours goes out the side as well, and if you can fit a gas water separator in you'll elminate 90% of what makes gensets obnoxious.

Don't have a genset, but my engine exhausts middle of portside.* If the wind is "wrong," I need to close the portside pilothouse door to avoid fumes.


-- Edited by markpierce on Tuesday 18th of October 2011 08:45:15 PM

"but most important is the huge preasure of beam seas wanting to force water back into the engine."

That is why the "North Sea" style exhaust is sometimes installed on offshore boats..

THe exhaust pipe is simply carried across the boat , so drains to either side with equal ease.

Easy on a work boat , probably a hard retro fit in a yachty interior.

Mine exhausts on the port side, but a little forward of midship *and is low. I have had boats rafted on that side and have been aboard them while my genset is running and it can barely be heard and is not smelly and does not soot them up.

Good points All-- I am leaning toward a side exhaust, less cockpit fumes, also seems a good idea to put it on the side that does not have the door to the cabin.

JohnP.

I had a transom exhaust on my previous Camano and did get some fumes in the back door if the wind was wrong (it was saloon type cabin) it may not be a factor on a side door cabin. On the Monk it is on the port side just forward of the midships, no complaints, we almost never raft up.
Steve W.

JohnP wrote:
Good points All-- I am leaning toward a side exhaust, less cockpit fumes, also seems a good idea to put it on the side that does not have the door to the cabin.

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Our IS on the same side as the main cabin door and so far we have never gotten any fumes inside even when the boat is up against a dock.* But if one is installing a system from new, I think the idea of putting it on the opposite side from the cabin door (if here is only one door on one side) is a good one.

Our genset exhaust is portside about 1/3 of overal length from transom. This puts it just forward of the cockpit but fumes are never an issue. We have a water separator which keeps it quiet and no-one objects to rafting portside.

The water separator*ensures that, in a beam sea, any water coming up the exhaust will simply exit at the water outlet below the water line. The downside is that I can't easily check for cooling water - have to go below and turn off the water outlet ball-valve to force the water out the side!

Regardless, the plumbing is a lot easier and shorter going out the side.

John, a small point ,if the thru hull intake is not already in place make sure that it is not too far forward and it is fairly deep set. I saw a aftermarket installiation of a generator and the yard cut the intake to high and to far forward. When the boat was under power the hull intake was not fully submerged and insufficient water was being drawn in to cool the generator.

A fairly basic mistake that meant the generator could not be used when the boat was underway.

I'd not drill another through hull for this exercise if you already have a working stern location. Another small point, diesel exhaust has much less CO than gasoline exhaust. Diesel engines are used in many closed locations, such as underground mines,*where you'd never consider a gasoline motor. The location of side vs*stern genset exhaust on our small trawlers*can enter into*mechanical, swimming (not an issue in the PNW),*or esthetics*aspects, but I seriously doubt safety.

As for exiting off stern, when at anchor there is usually enough breeze to carry any unpleasant odor aft whereas on side it may just blow it into cockpit. It never crossed my mind that a*stern vs side*exhaust for*a 3 - 12 KW*genset would be an odor issue, silly me. On a big yacht with an 80 kw genset*and the genset only 6 feet from the side vs 40+ feet from the stern and play toys galore hanging off stern, side makes a lot of sense.

Maybe dry stack would be best??


-- Edited by sunchaser on Thursday 20th of October 2011 08:14:24 AM

It looks like either side or transom discharge are both acceptable. After reading all the posts,*the installation seems to be*an engineering/construction consideration.* The larger vessels or aft staterooms seem to all have side discharges.* The smaller vessels or Europa type trawlers have transom discharges generally.

Good point Larry. Sundeck/ port side.

No holes have been cut in my boat for a generator, because it never had one.

As of now the unit is sitting in my garage and I am in the planning stage.

The boat will be hauled soon for winter storage and I am going to move a few things around to make this work, than I will put the generator *in next Spring.

I guess I got bored so I thought I would tackle another project.

Seacocks, strainers, fuel lines, filters, exhaust system, wiring, transfer switches, remote panels,battery, etc.**** It will be hard to bring this one in on Budget!

JohnP


-- Edited by JohnP on Thursday 20th of October 2011 07:33:26 PM

FF wrote:
"but most important is the huge preasure of beam seas wanting to force water back into the engine."

That is why the "North Sea" style exhaust is sometimes installed on offshore boats..

THe exhaust pipe is simply carried across the boat , so drains to either side with equal ease.

Easy on a work boat , probably a hard retro fit in a yachty interior.""

*

I have opted for the North Sea style for 3 reasons:

first there will hardly be any back pressure if one of the exhausts goes below the water, it just uses the other exhaust.

Second reason is that the exhaust will allways use the thruhull thats down wind - so very little exhaust fumes should get blown back into the boat.

Third reason, if the exhaust take a large wave directly, then the water would flow through to the other exit and not down into the muffler/wet exhaust. This requires that there is a goose neck on the exhaut pipe that feeds the 2 thru-hulls.

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I have chosen to have the North Sea exhaust for both the generator and the main engine.


-- Edited by Singleprop on Friday 21st of October 2011 09:46:08 AM

Singleprop -- What kind of vessel are you speaking of for the exhaust redo? What problems do you have with the existing setup?

Be very careful designing and building*the setup FF describes. It may be a good way to get water back into* your engines creating all sorts of grief. The words FF used*may not apply in your case - "North Sea and Commercial."* Peruse boatdiesel and read about the myriad of presumably well designed exhaust systems that allowed water to flow downhill into the engines with predictable results.


-- Edited by sunchaser on Friday 21st of October 2011 10:47:09 AM

sunchaser wrote:
Singleprop -- What kind of vessel are you speaking of for the exhaust redo? What problems do you have with the existing setup?

Be very careful designing and building*the setup FF describes. It may be a good way to get water back into* your engines creating all sorts of grief. The words FF used*may not apply in your case - "North Sea and Commercial."* Peruse boatdiesel and read about the myriad of presumably well designed exhaust systems that allowed water to flow downhill into the engines with predictable results.



-- Edited by sunchaser on Friday 21st of October 2011 10:47:09 AM

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It's not a redo - It's a new build "fishing boat". The exhausts are designed to avoid this problem.

Basically cooling water is introduced into the vertical part of the dry exhaust that goes down into the muffler, from there the mixture goes vertically up to the engine room ceiling, then forward and down (like a goose neck) to *a "T" where the two side exist connects.

That way - before a wave enters the engine - it will have to travel from the side exhaust exit into the T, then turn 90 degrees aft, then up into the goose neck under the ceiling, then down into the muffler, then a 180 degree turn up into the dry exhaust under the ceiling, then 90 degree horizontal and then finally another 90 degree turn down to the engine. And this is while the engine is producing gasses that pushes against the incomming water.

Can water enter the exhaust with this set-up?


-- Edited by Singleprop on Thursday 27th of October 2011 11:56:01 PM