Not for boating!
I bought the Coleman On-Demand Water Heater for use on a 30 day sailing voyage. It tested out ok at home with the exception that it wasted a lot of water before geting to the desired temperature. On a sea going sailboat water is a valuable commondity. Each time I used the heater it wasted at least a gallon of water. It finaly fell off of a bunk and fell to the cabin floor crunching the temperture control making it appropriate for the trash!