Compound Steam Engine
From Tugboat Socony 5
Bore: 19", 40"
Weight: 40,000 pounds
Length: 8' 9" ? Width: 6' 10" ? Height: 14'
This large steam engine was built in 1927 by the Staten Island Shipbuiding Company in Staten Island, NY. It turned a 10-foot-diameter propeller on the steel tugboat Socony 5, part of a New York Harbor tugboat fleet owned by Standard Oil Company of New York.
Developed about 1870, the two-cylinder engine was a practical power plant for small to medium-sized vessels for almost 80 years until superseded by diesel engines. This example worked with a steam pressure of 160 pounds per square inch. Steam from the boiler first entered the small high-pressure cylinder, driving its piston, and was then exhausted into the large low-pressure cylinder to expand further.
The engine's horsepower of 850 may seem modest by today's standards, but this figure is based on a working load output, unlike horsepower calculations for modern internal-combustion engines. This engine has 10 times the horsepower of the Paine compound engine of the Museum's passenger steamboat Sabino.