The Intrepid and her sister ships of the Essex class were the “Fast Carriers” of World War II, capable of moving twice as fast as the USS Langley, the Navy's first aircraft carrier. The Intrepid's power plant could generate close to 150,000 horsepower, and four steam turbines driven by eight boilers enabled her to reach maximum speeds approaching 32 knots, or more than 37 mph (59.5 kph). That speed was generated by four propellers. Each weighed approximately 27,000 pounds (12,247 kg), roughly the equivalent of ten automobiles, and all four were removed when the Intrepid was drydocked in 2007.