Do you have an exhaust out the midship side?

[auspain]

Have you owned or do you own a vessel with main engine and or genset exhaust out the midship side(s)? If yes, what has been your experience kindly please with additional smell compared to transom out (if any)? Underway? At anchor with no wind? Your feedback as an owner would be greatly appreciated please.

[rslifkin]

My boat is a powerboat, but the generator exhaust is on the stbd side, just forward of midship. Engine exhausts are on the transom. If the wind is light and blowing just the right way, the aft deck gets a bit fumey with the generator running, but it's rarely an issue. And fumes in the cabin are a non-issue if you give just a tiny bit of thought to which windows not to open in a given wind direction when the generator is running.

[auspain]

Thank you rslifkin for your reply, its a great help. We will be a 60 foot heavy displacement yacht for diving charters. If we ran the main engine out the sides and our generator out the transom, would you think this would be better for us with fumes or not enough odour to worry about?

[BillKny]

This is not at all an unusual arrangement for center-cockpit boats. The engine is located under the cockpit, and the exhaust is routed out the side of the hull to avoid running it through the aft cabin. This is how our boat is set up.

From a practical perspective, there is no real difference compared to a transom exhaust. If you are motoring in no wind, there is no exhaust in the cockpit. There are some light wind directions that can carry the exhaust up and over the cockpit, but that is equally true of an aft cockpit and transom exhaust, so not really a difference.

I have never noticed fumes from the generator in the cockpit while at anchor.

One minor issue from my perspective, is that you tend to accumulate some soot on the hull aft of the engine exhaust, but nothing that doesn't wash off with soap.

[auspain]

BillKNy this is what I was hoping for to actually hear from people that have this arrangement, thank you too most kindly for your time to comment. Its a huge help.

[GordMay]

[rbrazil]

Originally Posted by auspain

Have you owned or do you own a vessel with main engine and or genset exhaust out the midship side(s)? If yes, what has been your experience kindly please with additional smell compared to transom out (if any)? Underway? At anchor with no wind? Your feedback as an owner would be greatly appreciated please.

No additional smell vs transom exhaust in all situations.

[sailingunity]

Our previous boat had midship exhaust. The previous owner moved it up from the waterline because with no thru-hull was afraid a break in the hose would floor the boat. Unfortunately this also meant that any time we had a stiff breeze over the port size the cockpit got drenched with exhaust water. OK, in a perfect world you wouldn't be motoring with a stiff breeze available, but we were in a rush!

[Scrimshaw4]

I have a center cockpit boat that had the main engine exhaust coming out the aft starboard side of the hull and the generator exhaust coming out the port side just aft of midship. The generator exhaust was only a problem if someone rafted on my port side or was running and I tried to board from my dink on the port side with someone rafted to starboard. The main engine exhaust was another problem all together. If the hatches or port lights in the aft cabin were open with a light aft or port quarter breeze while under power the fumes and exhaust spray would come into the cabin and the cockpit as well. After several years of dealing with it I rerouted the exhaust to the stern. It was a major improvement in both air quality and sound. JMHO

[Scorpius]

Scorpius has her exhaust out the port side, at the waterline, at just about maximum beam. It's been like that for 35 years and has never been a problem. It's a dry exhaust (no salt water thru-hull, salt water pump, or heat exchanger) and so has to have a big loop of exhaust pipe as high as possible before turning down to the outlet in order to keep water out of the engine. In the 35 years and 6500 engine hours I'm on my second automotive muffler and it is showing no signs of imminent failure (touch wood! )

Very occasionally when running under power, when there is a very light breeze from behind just a hair less than the boat speed, we get exhaust fumes into the (aft) cockpit - but very rarely.

[sailingunity]

Originally Posted by Scrimshaw4

After several years of dealing with it I rerouted the exhaust to the stern. It was a major improvement in both air quality and sound. JMHO

This was our plan as well but we sold the boat before we got to that project. If you have the space under the floor!

[auspain]

Scrimshaw4 and sailingunity you both raise very good points thank you. I must consider Portlights openings going aft of outlets.

[SV__Grace]

We have a center cockpit sailboat with engine and generator exhaust on the SB side at the waterline, partially submerged.

The exhaust goes mostly into the water and only occasionally if the wind is on the beam and we're listing/heeling a bit will we smell any exhaust.

The downside of this arrangement is that you can't clearly see the raw water being expelled like you can with transom mounted exhaust, but both have "pissers," a pee-like indicator that shows the raw water system is working.

[MV Caroline]

Caroline has a Nordic style athwartship exhaust tube exiting both port and starboard aft of the engine. It also serves as the over board for the bilge pumps and filtered engine crankcase vent. The gen set also exhausts to starboard. I've never noticed any fumes aboard from either the main or the 20kw northern lights gen, nor have I seen any soot accumulation. I think it's more a function of clean burn than exhaust port placement, as long as the port is low enough and isn't being choked below the waterline.

[Paul Howard]

We had a center cockpit boat with engine exhaust going out port side not far above the waterline.
Of course, boat is loaded heavily for cruising and exhaust was closer to the waterline.
We occasionally got exhaust odour in the cockpit when wind, etc. was just right, but one time the boat got swatted by a big wave (engine not running, heeled opposite side) just right and water was forced back up the exhaust elbow into the engine. We were on passage, running the engine every day and with use of decompression levers, water was forced back out, engine eventually started and no permanent damage.
At the next anchorage I puzzled over what to do. The exhaust outlet had a pipe stub sticking out the side of the hull about 1/2" so I cut a piece of old yellow foulweather gear material to a rectangle, wrapped the end around the pipe stub, about 1 1/2 turns and hose clamped it in place with about 8" of it flopping free. Thus when sailing it and the engine off it flattened against the hull and acted as a flap valve and closed.
When running the engine the exhaust water and fumes were transferred directly into the water and seemed quieter and less fumes blown into the cockpit. It would get barnacles and such growth on it but when sailing it seemed to get cleaned off again.
We sailed many thousands of miles with that in place and sold the boat with it still in place. A very low-tech solution. The only problem was that people used to shout that something was dragging in the water off the side of our boat.