Investigating Spurious CO Alarms on Boats

[sophiecentaur]

Can anyone think of a reason why a CO detector should give spurious alarms on a boat?
I made some toast for breakfast and a cup of coffee but the Stove had been off for several minutes and the gas cock was turned off immediately after using the stove. The engine (diesel) had not been run and no chemical bottles or tins had been opened. The (new) Kidde CO alarm registered 260ppm and took about 15minutes to give a zero reading again,despite my opening both fore and main hatches and a reasonable breeze over the water.. I had to keep taking it outside into the cockpit to make it shut up!
The internal volume (living space) - almost 7m by 3m and 1.6m high in places.

What chemicals,other than CO,could be responsible?
(I thought this forum was the appropriate place for this post.)

 

[chemisttree]

Is it just the CO detector or does it also detect explosive gases?

 

[Borek]

I did some googling trying to find out what kind of detector it is - Kidde claims it is some kind of patented electrochemical detector, but without knowing details I wasn't able to find anything in a reasonable time.

My first idea was the same as that of Chemisttree - that the detector reacts to anything that con be oxidized. But there is no mentioning of such a thing in manuals that I downloaded from Kidde website.

 

[sophiecentaur]

Thanks for getting back, chaps.
The device does claim to be CO specific but that some 'chemicals' can affect it. Internet searching wasn't particularly helpful for me either, Borek - I thought that the experts here would be a better source of wisdom.
The thing that bothers me is that I hadn't actually changed any conditions. I keep a load of different cleaners and solvents on board and some of the lockers are pretty well sealed. I could understand a waft of something getting out when I opened a locker but I was having a sloppy time and did no jobs that morning. I guess I'll have to go round, opening various bilges and lockers until something trips it again.
I think I really need a CO detector as I have just installed a small solid fuel heater, running on charcoal briquettes. The flue is not long and there is always the possibility of a backdraft when facing into the wind. There is definitely low pressure around the main hatch which can pull smoke out of the bottom of the stove in gusts, when it has just been lit. I can stop that by lifting the fore hatch a tad but that would rather defeat the purpose by letting cold air in! I have slept with the heater going and am still here to tell the tale so I think the risk is small.
I am also working (mentally, so far) on the design of a better cowl for the top of the flue.

 

[chemisttree]

Some of those Kidde detectors detect more than just CO, they detect explosive gases as well. I've read accounts online that some of those detectors have a problem with false positives as well. One account called it the FBT, which stands for the Fart Beeping Thing. Apparently it detects air biscuits as well as CO! Could volatile oils from your coffee, toast, flatulence, coffee breath, etc... contaminate the sensor and give you false positives?

I feel a morning breath test coming on...