On demand water heater
People need to be REALLY careful using the gas on-demand heaters. Poor installations have asphyxiated unknowing sailors before they were aware of it because the heater uses up so much of the oxygen inside the hull, and a small leak replaces the oxygen with carbon monoxide... Many magazines have had articles on what to watch out for. Certainly never to use under way. (Putting the thing on gimbals would be quite difficult to make safe, no?) Not to say that people don''t use them, but to be careful.