CO in rear berth 32xx, 38xx-gctid804128

[Mr._Darcy]

After reading a comment on a recent post about a carbon monoxide fatality in the rear berth of a 32xx while under way. I decided to install a CO detector in the rear berth. I was wondering though how much of a problem it might be with the diesel engines as compared to gasoline engines. Has anybody ever used a CO meter to test this area while under way? We normally have the bilge blower running on Mr. Darcy while under way as the smoke alarm has sounded a time or two. Of course after discovering that one of the vent louvers was on backwards, and then reinstalling it correctly the problem went away. The engine compartment was actually being pressurized with both louvers scooping air. We still run the blower as a precaution. On long fishing trips someone will normally want to nap in the rear berth. Just curious about others experiences in this regard. The 38xx series also has a berth that shares a wall with the engine compartment.

Greg

[green650]

Is the C0 a product of the exhaust?

I get exhaust smells in the rear cockpit of mine when cruising around at trawler speeds because of the station wagon affect. It's easy to see how that would enter through the cabin entry door which is far from sealed, and is usually open anyway.

Definitely open the windows in the berth if someone is going to sleep there.

[Uncle_Bob]

You likely won't get carbon monoxide from your diesels as diesel produces less CO, but you can suck in a neighboring gas boat's engine or genny exhaust so CO detector in sleeping quarters is a really good idea. I have always used Fireboy hard wired ones, but they have a five year pre-programmed life so become expensive over time. Next time I will use a battery style home use one.

[Norton_Rider]

"Uncle Bob" post=804137 wrote:
You likely won't get carbon monoxide from your diesels but can suck in a neighboring gas boat's engine or genny exhaust so CO detector in sleeping quarters is a really good idea. I have always used Fireboy hard wired ones, but they have a five year pre-programmed life so become expensive over time. Next time I will use a battery style home use one.

I switched to home style, battery operated detectors on my boat and RV. I got the style with an LED screen that shows the CO concentration. They work fine.

[Guest]

I have 2 CO detectors on my 32, one in the rear cabin, one in the galley. No hits at all ---

[Solandri]

"green650" post=804130 wrote:
Is the C0 a product of the exhaust?

Carbon Monoxide is formed when there is insufficient oxygen in the fuel-air mixture. It's at a higher energy state than CO2, so the carbon in the fuel naturally wants to bond with two oxygen atoms to form CO2. That puts it in a lower energy state, releasing more energy. But if there isn't enough oxygen, CO will form instead. Kinda like rolling a ball down some stairs - its potential energy makes it want to go all the way down to the bottom (CO2). But if the stairs are spaced too far apart (not enough oxygen), sometimes it'll stall and stop on an intermediate stair (CO). A small amount of CO forms naturally even in an oxygen-rich mixture since a few carbon atoms randomly won't find enough oxygen atoms to form CO2.

Since diesels normally run with excess air (turbo-charged even), they tend to have less problem with CO production. But any situation which starves the engine of oxygen (high altitude, obstruction in air intake, loss of compression, too-rich mixture, leaking of exhaust air back to the intake, etc) can lead to production of excess CO, even in diesels. In theory, the fact that diesels ignite the mixture based on pressure, whereas gas engines force the ignition with a spark, implies that in low-oxygen situations a diesel simply won't run whereas a gas engine can be forced to run. But I gotta figure once some of the diesel fuel starts to combust, that produces enough energy to get the rest of the diesel to ignite even in a oxygen-poor mixture.

It kills because hemoglobin has a higher affinity for CO than O2. i.e. It bonds so tightly to your blood that it blocks oxygen from bonding to it, and your blood become useless for carrying oxygen to your cells. Cyanide acts similarly. The only fix (aside from a complete blood transfusion) is time. A few O2 atoms randomly hit the hemoglobin with enough energy to knock the CO off, at which point the hemoglobin can start to work normally again. So the longer you're exposed to high concentrations of CO in the air, the more dangerous it is. And immediate removal from the high-CO environment may not be enough to prevent death.

[Mr._Darcy]

Your dissertation brought back memories of nearly the same information provide during flight school. The difference being that the effect of partial pressures was brought into the discussion.

Thanks for sharing that explanation. As a side note, CO is possible with the low oxygen combustion of any fossil fuel. That includes natural gas and propane. A good reason to have ventilation when operating propane or CNG stoves and heaters aboard, or at home.

Greg