Steam engines generally operate at about 8% efficiency. In other words most of the energy goes up the smoke stack and only 8% actually provides horsepower to move the boat. It takes about 400,000 BTU per hour to run our 10 HP engine at 600 RPM.

The engine on the Susanna uses about 80 pounds of wood per hour, more than enough to heat a home for an hour during an Alaskan winter. The wood fired boiler heats about 50 gallons of water per hour to generate steam at pressures ranging between 60 and 150 PSI. At 150 PSI the water/steam temperature is 365 degrees. Steamboat engineering requires constant management of fire in the firebox, water level in the boiler and steam pressure to provide safe and consistent operation.

Steam power is inefficient but it sure is a lot of fun.

Captain John

A Semple double expansion compound steam engine powers the boat at a hull speed of about six knots. Each of the engines two cylinders provides power on the up and down stroke giving it four power strokes per revolution. Steam enters the first cylinder where it is partially expanded before it is sent to the second larger diameter cylinder where it is further expanded. The exhaust steam goes through a keel cooler were it condenses back into water to be injected back into the boiler to be turned once again into steam.      See how a steam engine works. The Laurie Ellen is a double-acting steam engine.     Tickets are available on any Princess Cruise ship, at the Mount Roberts Tram or by calling us at (907) 723-0372.       Come on aboard.

Custom Tours Available