If we ever had a super heated steam leak in the engine room we were trained to grab a broom or other stick and wave it in front of you from floor to above your head while moving slowly. When the broom was cut in half by the invisible steam jet you found the general leak location.

Sea water needs to be desalinated before being used in a boiler. If you only just filtered it for solids the salts in the water would form a nasty layer of scale on the water side of the boiler tubes quickly resulting in poor heat transfer and failure of the boiler tubes. When we make our boiler water on my ships we only use water where salinity is under 5 PPM