Topside exhaust

[rgano]

I have had lots of experience with engine/boiler exhausts from topside stacks. Probably the worst experience was when I was the conning officer taking the battleship USS IOWA BB-61 through the Panama Canal. The captain decided that the ship needed to be conned from the upper conning station on the 08-level WAY up in the superstructure instead of from the normal conning station on the 04-level navigation bridge. We had used the 08-level station only one other time in my three years aboard, the first time we got underway from Pascagoula for a sea trial. This day in the canal the wind was astern and yes, we were above the tops of the two smoke stacks. The stack gas wafting over us left us gasping for breath and trying to find clear air, and my white uniform was gray when I came off watch that afternoon. In the five steamships I was assigned to in the Navy, all tended to be somewhat less than clean topside as a result of soot expelled from the stacks when boiler tubes were steam cleaned once a watch. Oh, we tried when at sea to get a course with the wind off a bow in order to clear the soot from the ship, but eddies would form somewhat thwarting the effort, and one can guess at the resulting mess when tubes were blown in port when shore power was not available! Even aboard the modern gas turbine powered destroyers I worked aboard until 2012 you can get plenty of whiffs of exhaust when on deck aft. Now fast forward 35 years to March and April this year as my wife and I brought a dry exhaust boat with a stack for one main engine and two generators just aft of the bridge from Norfolk to the Gulf Coast. The engine in this ioat had been serviced including new injectors and certified ready to go by the JD techs in Norfolk, and the gens were run with good load. Nevertheless, after 30 days in which we did get some rain, the fresh US flag placed on the flagstaff aft on the upper deck at the start of the voyage was gray where it was supposed to be white, the dinghies carried up there were sooty and the deck area was obviously in need of lots of scrubbing. Then too there was the almost subliminal, tinny noise one gets from such an exhaust, especially when the pilothouse doors or windows were open. Walking on the main deck on the downwind side, I could usually smell the exhaust as eddies swirled around. Just some idle thoughts for anybody considering a vessel with a topside rather than side or stern exhaust.

 

[GregBrannon]

Thanks for describing your experience with these exhausts - both the big ship and smaller. Interesting.

Greg.

 

[Rusalka]

I've always wondered if you can smell exhaust on the Nordhavns if the wind is blowing right.

The drawback of stern exhaust, especially in a trawler, could be the station wagen effect with fumes in the cockpit.

 

[Pete Meisinger]

I made a 10 hour run one day with an eight or so mile and hour wind on my stern. My trawler does about 7kn on a nice day and 8 Kn with a stern wind.

It wasn't awful but it was a bit smelly.

pete

 

[ancora]

We had a slip in King Harbor, Redondo Beach California, many years ago. The marina is adjacent to a PG&E generating station. Whenever they blew the stacks, soot would fall on boats in the marina, whereupon the company would pay for the cleaning. When they installed scrubbers in the stacks, the problem went away.

 

[Comodave]

With a certain direction of wind and our 10 mph cruising speed we sometimes get an exhaust smell that my wife hates. I don’t like the smell but it isn’t that bad.

 

[firehoser75]

I moor in fairly busy commercial port (mainly fish boats and tugs) where all of those boat have dry exhausts. Often get deposits on the decks and roof from?? Could be from the Seaplanes?
One year it was particularly upsetting. I had just finished spending several days cut polishing, polishing, then hand waxing my boat's topsides. Two days later I was back down to the marina only to find that the roof of my boat was covered with dark spots that were very visible and would not wash off!!! Not happy about that, but who would I try to blame, assuming that was even a course of action. I just left it, cause I figured it would just happen again.

 

[Lepke]

Black spots are usually from either diesel engine or stove exhaust from a nearby boat. It also can come from smokestack industries and power plants. A lot of big diesels put out some soot. Especially older ones on ships nearing their end. So do boilers.

 

[hollywood8118]

I've always wondered if you can smell exhaust on the Nordhavns if the wind is blowing right.

The drawback of stern exhaust, especially in a trawler, could be the station wagen effect with fumes in the cockpit.

In a word... YES


I know there are lovers of drystack exhaust systems.. I'm not one of them.
I have written this in the past, we had a neighbor yeas ago with a old DeFever that would soot us up at times. Even found him scrubbing down our GB36 once, to his credit he was at it for hours. The N46 i did a bunch of delivery runs on had a drystack, I never liked the noise of the flapper or the smell on the bridge in the wrong conditions.
On the other side of the coin.. on a commercial boat it makes sense.
HOLLYWOOD

 

[firehoser75]

Black spots are usually from either diesel engine or stove exhaust from a nearby boat. It also can come from smokestack industries and power plants. A lot of big diesels put out some soot. Especially older ones on ships nearing their end. So do boilers.

Sounds like my black spots were from the "work boats" around me! Too bad, but I guess no alternative but put up with it, or move to another marina.

 

[guy with a boat]

Our boat has a dry stack exhaust and we haven’t experienced the problems mentioned. The boat is fairly new (2015) so the engine probably runs cleaner than some older boats. The stack exits above and aft of the pilot house.

I can’t say it will never happen, but we don’t have soot nor smell. Our boat stays clean and, since someone will ask, I’ve never seen fallout from the stack on the dock or neighboring boats in a marina. We have an enclosed pilot house and no fly bridge, so we haven’t experienced any smell from the exhaust. The stack is enclosed all the way from the ER up and fully insulated, so no heat or noise issues. The outlet is far enough away that the boat is very quiet.

This boat is our first with a dry stack, and I have become a big fan. I’m sure it depends on the boat but, for us, it is a great system. Losing the wet exhaust eliminates a bunch of maintenance items, such as seawater pump, impellers, seawater heat exchangers, and corroded exhaust elbows. There are no perfect systems on a boat, but a dry exhaust can have a lot of advantages.

 

[Pete Meisinger]

Most fish tugs, at least on the great lakes have a huge woodburning stove on board. When the boat is empty, on the way out to check nets there is generally a visible list to the side carrying the stove.

You want to talk about dirty? Don't know about nowadays so much, there isn't many of those tugs left on the Great Lakes, but.. Those guys would go out in almost any weather. If it was -20 they would crash through the ice or ride up on top of it and crush it down. Meanwhile that big wood stove was roaring away in the boat. Burning waste oil, filters, old tires, contaminated fuel, the works. If it could be made to burn, into the stove it went.

pete

 

[IRENE]

I've always wondered if you can smell exhaust on the Nordhavns if the wind is blowing right.

The drawback of stern exhaust, especially in a trawler, could be the station wagen effect with fumes in the cockpit.

No smell on ours, but the OP’s observations are applicable on our boat too.

 

[FF]

There is no exhaust smell or danger if you convert the diesel to run on natural gas or propane as DD did for city buses, or local delivery trucks.

 

[DCDC]

We have twins with high dry stacks, about 25’ above the aft deck. With a following wind we notice some exhaust smell but not appreciable. The exhaust is always clear, even when starting, so no soot on the aft deck. We cruise for from January through July and spend hurricane season at dock on the Gulf Coast.

If the engines aren’t started for a month or so there is some soot loading, I think is due to condensation in the exhaust risers. In these cases we have a fine mesh net with a rim in the shape of the exhaust discharge. It fits on an extension pole and it catches most of the soot when starting. Clean afterward on the dock.