one of the major problems with catalytic heaters is the lack of visible flame, if the pad looses its conversion properties then unburnt (converted?) gas falls over the face of the pad and can either be burnt off by the pilot light or leak unnoticed into the bilge. I have seen , just once , a large flued catalytic heater that worked very well, the flue was fan assisted and the heater would not run if the fan failed. It was an American make, whose name escapes me.
I have seen (at boat shows no less) CE marked heaters, research showed that the CE marking was for use in sheds and greenhouses, the retailers, chandlers, took the view that it was "buyer beware".
PM