I got a phone call from a friend today about a close mate of ours who was found dead in his bivvy in the past week.
The Cobb was on in his bivvy, and it looked like the angler had fallen asleep in his chair sat upright.
From the description, another sad case of carbon monoxide poisoning.
Another friend called me about it, asking if I had heard. I actually had a bit more info about the Cobb than Mark, but he had seen a YouTube video where in tests with a Carbon Monoxide detector in a zipped up bivvy, the fatal level with Cobb briquettes or pellets is reached in around 10minutes, a standard gas stove will reach fatal levels in 30minutes.
An experienced angler, who took a chance and sadly paid the price.
The thing with any level of carbon monoxide is that it makes you feel tired and can send you to sleep, so you simply never wake up.
Please please, forget bivvy heaters, stoves on inside a zipped up bivvy and go for decent clothing and sleeping bag instead.