In 1931 diesel technology wasn't considered reliable enough so Harvey was built with five gasoline engines.  Five were needed to provide the power required to drive the boat and operate the pumps.The gasoline engines were replaced with five 600 horsepower diesels in 1957.

These current engines are Fairbanks - Morse opposed piston Model 38F5¼ which consist of 8 cylinders with 16 pistons.

These five main engines provide the power for both propulsion and pumping. The complex engine room also contains a large array of auxiliary equipment including two independent diesel-generator sets and powerful air compressors. The engines are started using compressed air, and during the boat’s service life air pressure was constantly maintained to allow for a quick response to alarms.

Harvey is an electric boat. Her five diesel engines drive generators which provide electricity for propulsion.

 

 This power is then channeled through two switchboards where the engineers distribute it. The forward one controls the boat’s many auxiliary electrical systems.

 A main switchboard aft controls power to Harvey's massive propulsion motors.

Each of these two motors is connected to its own propeller shaft. They can develop 1065 horsepower at 425 rpm.