Smaller and slower ships today use marine boilers with features like vertical superheaters and retractable sootblowers. These boilers can produce 17,500 kg/h of steam for 10,000 shp. Firing from the top improves combustion performance, and having two burners per boiler enhances part-load performance. Using better materials like 9% chrome in the superheater can extend its lifespan three times longer than 2-1/2% chrome material.