From the continental paddlers I know, they take their boiler water from the river or lake, where they are sailing, through filter systems.
But what do paddlers or steamers sailing on the sea with salt water? When sailing between continents?

Andy

Hi Andy......depending on the vintage you are considering, most seagoing steamers used sea water cooled condensors...so the exhaust steam from the engine is fed to a condenser where it reverts to useable boiler feed water ......marine condenser shells are of a similar volume or dimension to the boiler shell itself

I addition to this, later vessels also supplemented this with sea water distillation ie., boiling and condensing the sea water to usable fresh water

Modern day cruise liners [with diesel engines] make all of their own fresh water when at sea........... Derek