Euterpe Times V3 NO. 42 - Maritime Museum of San Diego

Marine Steam (cont)
was used in the American cruiser Olympia, built six years before
the Berkeley, also at the Union Iron Works in San Francisco.
Compared to the Berkeley’s single engine of 1163 horsepower,
the Olympia had two engines of almost 9,000 horsepower each
(6,750 designed). The triple-expansion engine worked best at
pressures of 155-185 psia, so that the Berkeley was at the upper
range of desirable steam pressures for the triple-expansion
design.
The next logical step was to divide the steam cycle among four
cylinders, the quadruple-expansion engine. This design used
steam pressures of 240 psia or higher, and was the final
development of marine reciprocating steam engines.
The next step was the turbine engine, which could use much
higher steam pressures and temperatures. The standard USN
steam plant of WW II used steam at 600 psia and 850 °F.
Further Reading
Diagram of the Watt Steam Engine in its most basic
form showing the improvement of the separate
condenser, which was not found on the Newcomen
steam engine.
of the atmosphere, the engine was smaller and lighter than a
condensing engine, and not much less economical. This is the
engine that powers steam locomotives.
10
High-pressure steam required better materials and construction.
Once these became available, it was possible to supply highpressure
steam to condensing engines, thus saving steam by
closing the steam valve with the piston near the start of its stroke
and using the expansive power of the steam for the rest of the
stroke. The higher the initial pressure and temperature, the
earlier in the stroke the steam valve could be closed. A large,
single-cylinder marine engine is shown in the first picture.
With steam of higher pressure and temperature at the beginning
John Elder, in 1854, divided the steam expansion into two
cylinders, so that each cycled through a smaller range of
temperatures and pressures. This was called the compound
engine, as used in the Medea, and was suitable for steam
pressures of about 100 psia. The compound engine was
sufficiently economical to enable steamships to sail almost
anywhere in the world.
Improvements in materials and designs, even in lubrication,
allowed still higher pressures and temperatures, and this allowed
a further division of the steam cycle into three cylinders, the
triple-expansion engine. The British Navy used the first tripleexpansion
engine, in a cruiser in 1887, and that type of engine
Pacific Time Machines:
Recent Replicas & New Traditional Vessels
Modern versions of old wooden ships, boats, and canoes have
blossomed around the world in the past half-century. Pacific
Time Machines is a wide-ranging survey of articles about many
of those in the Pacific, from 1913 to 2005—each written by the
designer or another involved in the project. Subjects range from
HMS Rose and its re-creation as HMS Surprise for the movie
“Master and Commander,” to the schooners Californian and
Lynx, to Hawaiian voyaging canoes, feluccas, Chinese junks,
and Chumash Indian board canoes. Authors include renowned
naval architects Melbourne Smith and Phil Bolger, and Hawaiian
canoe navigator Nainoa Thompson.