False Smoke Alarm

While traveling on the fly bridge in dense fog a smoke alarm in the saloon below began to blare. It is mounted at ceiling height. I immediately went below and searched the entire boat from the engine room to the fly bridge and could find nothing amiss. There was no smoke odor or any signs of smoldering wires or fire. Engine temps were normal and all belts were normal as well. I had to remove the batteries from the alarm to make it stop.

After the fog cleared I reinstalled the batteries and the alarm stayed quiet. It has not gone off for the last week. Any ideas if the fog could have caused this strange event?

Is it a multiple alarm, including CO?

Could it be the station wagon effect which could be exacerbated by the heavy air?

It's a smoke alarm only. Not sure about station wagon effect but perhaps.

Sheesh, I'm sure that was unnerving. Especially since you haven't found the culprit. Good luck!

Folks, if you leave your aft doors open when running, then take a walk down into your salon a time or two. The smell with give you an indication as to what is being sucked back into your boat.

Not a big deal while running and there is plenty of air flow.

Just something to understand and be aware of.

I don’t see how fog could have set it off.

Yes. High humidity can set of smoke detectors.

Agree, high humidity, usually when chilly has set off my detectors. (They are home style, not marine)

A short blast from a hair dryer shuts them right up.

Photoelectric sensors will alarm when anything that will reflect light enters the the sensor chamber. Particulates (smoke) or water droplets (fog) will do the job.

sbu22 said:

Photoelectric sensors will alarm when anything that will reflect light enters the the sensor chamber. Particulates (smoke) or water droplets (fog) will do the job.

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That must be it. It's now 2-weeks and it's still quiet. I'm live aboard so I'm here all the time.

Smoke detectors come in two varieties: Ionization and photo electric. Ionization looks for polarization of ions caused by oxidation of burning. Photoelectric works on an obscuration principle. Fog obscures so there you are.

Plus, if they are ten years or more old they should be trashed.

Xsbank said:

Plus, if they are ten years or more old they should be trashed.

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Funny you should say that. It was 11 years old and I replaced it today with an ionization model that has a 10 year Li battery. I sincerely hope I outlive the battery.