Possible Carbon Monoxide Leak

Try running with gen off. If problem goes away its not the engines but gen

 

You don't necessarily have to have a leak sometimes if the motor is running and the cabin door is open you may get what i like to call The Station wagon effect where the fumes may draft down into the cabin . Try closing the door and all hatches and see what happens !

 

And with or without the A/C or heater running. Any leak between the engine room and the cabin will be amplified by the salon blower. Had this in a 1989 Carver until we sealed up all the entry points, of which there were plenty.
your boat is new enough that this "shouldn't" be the issue, unless you have been running stuff between the engine room and the cabin space.

 

Buy a couple of these. The will tell you the max detected CO ppm. Might help diagnose.


https://www.kidde.com/home-safety/en/us/products/fire-safety/co-alarms/kn-copp-b-lpm/

Be careful. I would assume new CO monitors are correct until verified otherwise.

 

Along the lines of what was mentioned above about the long-established, and very possible, station wagon effect, did you have any canvas up/down? Fwd deck open/closed? Speed at the time of alarm?

When you got the alarm, did you turn the blowers on?

 

It’s back drafting into the cabin. Or as Lazy says it’s station wagon. Make sure the cabin door is closed, even while at warmup or cool down my door stays closed. Also any windows (like my old SeaRay has) should be shut. Mine always goes off when the canvas is on, I make sure the vent windows are open.