Yes it's true, Sleeping on the boat while it was on the trailer (boat is unable to weather vane) the wind came up pretty strong from the stern. Our CO alarm did go off even though the heater was outside. We finally figured out the wind must have been blowing across the heater and up to the weather boards allowing a little exhaust in?? Turned the trailer around, aired out the boat, reset the alarm, and didn't have any other problems. As long as the heater is outside, and I have the CO alarm inside I feel comfortable. But that's just me. You have to make your own decision. I know a lot of folks that "crack" the hatch and use things like Origo heat pals or Coleman catalytic heaters inside. That I wouldn't be comfortable with. You'll have to make your own call. Gary's advice is sound. You can't get CO poisoning if you don't make any CO! ************************************** See what's new at http://www.aol.com