I have had Webasto hydronic systems on 3 boats. I did not find them to be noisy (the furnace was in the engine room) nor particularly thirsty. In cold weather (freezing or near freezing) we would leave it on a low setting when not aboard. The only caution I have is you may want to consider either a separate start battery or a more robust house battery bank if that's the battery bank you intend to hook it to. They are sensitive to volt/amp drops.