We have 2 Carbon Monoxide detectors on our boat and have experienced alarms that are puzzling. While cruising - with the canvas up and trailing winds we experienced alarms in the middle of the night 5 to 6 hours after shutting the engine down. Then again this morning - after a 40 minute run into the wind back to the dock after a day-sail yesterday and having the companionway and hatches open for several hours afterward - I get an alarm at 5am this morning.
We try to have the Dorades open and companionway closed while motoring but we do open it while sailing then sometimes forget.
I'm pretty sure my exhaust is in good shape but will be checking it out thoroughly today.
The alarm delay is what is really puzzling. Just looking for some suggestions or to see if anyone else has seen this.
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Harold Baker
S/V Lucky Duck
Duncan Bay Boat Club
Cheboygan Michigan - Lake Huron
1989 C-36 mkI TR/WK M25XP
How old are the alarms?? The life of the sensor is 7-10 years. Since 2009 IIRC alarms should have end of life notification of some sort.
Les
Les & Trish Troyer
Mahalo
Everett, WA
1983 C-36 Hull #0094
C-36 MK 1 Technical Editor.
Commodore
Les: The alarms are only 3 years old and seem to test fine. I bought a new one with a digital display so I can see where I am level wise. Haven't been out to test it yet but will update this post when I do.
I did some reading and there are a lot of varied "Opinions" on how the detectors work. So I ended up on the Kiddie site where they explained how their detectors work. I think the delayed alarms are explained by the Time/PPm function of the alarm. I'm sure these are MFG dependent
Carbon monoxide levels that will set off your alarm
Carbon Monoxide Level Alarm Response Time
40 PPM 10 hours
50 PPM 8 hours
70 PPM 1 to 4 hours
150 PPM 10 to 50 minutes
400 PPM 4 to 15 minutes
Beyond that I did some looking and found that my vent fan hose was torn and not venting out the transom - but back into the boat.
I taped up the hole but will be replacing the entire hose and maybe the fan as my next project. I rewired the fan so I can run it independently of the ignition switch.
Another question - Is the Blowby tube a source of CO into our boats?
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Harold Baker
S/V Lucky Duck
Duncan Bay Boat Club
Cheboygan Michigan - Lake Huron
1989 C-36 mkI TR/WK M25XP
I wouldn’t think crank case vent would be a significant source of CO unless you have a very bad ring. CO is a byproduct of combustion so stays on the top side of the piston. I do route my vent to an oil separator then back INSIDE my air cleaner.
Les & Trish Troyer
Mahalo
Everett, WA
1983 C-36 Hull #0094
C-36 MK 1 Technical Editor.
Commodore
I think Les is right the crankcase breather should not set off the detector but research on the forum about rerouting the hose back to a K&N airfilter ,no smell and no oil mist
Bill Miller
S/V Lorraine
Pacific Northwest,Sound Sound
Grapeview,Wa
1990 Mk1
My experience with CO2 monitors is that they like to go off in the middle of the night, for no good reason. Probably just our exhaled CO2.
my understanding is that Diesel engines produce very little CO2. Gas engines, like my EU2000 will produce dangerous levels of CO2.
I believe the fan is mostly for heat removal. If you’re engine is smoking down below or putting off a strong smell, you have other issues.
2000 C36 MKII 1825
While you may exhale carbon dioxide it’s not harmful. You would have to have special physiology to exhale carbon monoxide.
Les
Les & Trish Troyer
Mahalo
Everett, WA
1983 C-36 Hull #0094
C-36 MK 1 Technical Editor.
Commodore
Guys - thanks for the info. I have routed my breather tube through an oil separator but just terminated the output about 1" from the K&N filter I have installed assuming that it would just suck the gases back in. No smoke or exhaust fume smells when running but I did just rewrap the riser and replace the hump hose a year ago this last spring so I will be looking at all the joints again. Muffler is not leaking anywhere I can see but I will be looking closer to that as well.
Les - I have always thought that blowby was a result of combustion gases getting past the rings - so it might contain CO. Am I all wet on that subject?
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Harold Baker
S/V Lucky Duck
Duncan Bay Boat Club
Cheboygan Michigan - Lake Huron
1989 C-36 mkI TR/WK M25XP
No not all wet, but to get significant CO your rings would have to be really bad. And you would see blue smoke out the exhaust. I’ve been told is the pumping of the engine is the majority of it. Lots of oil vapor.
Les & Trish Troyer
Mahalo
Everett, WA
1983 C-36 Hull #0094
C-36 MK 1 Technical Editor.
Commodore
Harold
Since you allready have your breather going to a seperator go ahead and drill a hole in the K&N filter and put a aeroquip fitting in and run the gasses into the filter
Bill Miller
S/V Lorraine
Pacific Northwest,Sound Sound
Grapeview,Wa
1990 Mk1