The last 2 times I went down to the boat I opened the cabin to find the Carbon monoxide alarm going off. The first time I opened the hatch, reset the alarm and that seemed to quiet it. Yesterday same thing, open the cabin and the alarm is beeping. This time it would not reset. I even unplugged the 12v wire to it for a minute then plugged it back, still beeping. I left the hatch open for the afternoon with a good 20kt wind blowing into and through the cabin. Each time the engines or the generator were not running for a period of several days. I cannot come up for a good reason for CO to build up in a closed outboard boat, and especially an open cabin with a good breeze. I'm beginning to think its the sensor. anybody else experience something similar? Thinking of taking one of the ones from my house down and checking it with a different sensor.