A recently released federal report on houseboats warns their owners to be careful about carbon monoxide poisoning. The boat’s generators create the fumes. Water patrolman Alan Barborek says boaters need to check them all the time. The report, from the National Institute for Occupational Safety and Health, specifically warns against playing near the back of houseboats where the fumes tend to gather, and from swimming behind the boats. Five people died in Missouri from carbon monoxide poisoning in 1999, four of them on the same boat.