yea 90% of marine steam engines are whats called "Triple expansion steam engines" meaning the steam enters 3 different pressure levels each progressivly lower then whats left goes to the condensor to be turned back into water. The only marine steam i know of that is not a triple expansion is a Clyde Puffer 
The puffers developed from the gabbert, small single masted sailing barges which took most of the coasting trade. The original puffer was the Thomas, an iron canal boat of 1856, less than 66 ft (20 m) long to fit in the Forth and Clyde Canal locks, powered by a simple steam engine without a condenser, since as it drew fresh water from the canal there was no need to economise on water use. Once steam had been used by the engine, it was simply exhausted up the funnel in a series of puffs as the piston stroked. As well as the visual sight of a series of steam puffs following the boat, the simple engines made a characteristic puffing sound.
By the 1870s similar boats were being adapted for use beyond the canal and fitted with condensers so that they no longer puffed, but the name stuck. Some non-condensing puffers (included those with compound engines) were built until the 1920s when purely-canal traffic decreased and the vast majority of coasters had to operate in sea water.
Jack.
