In the warm shadows of the boat barn, the steamboat Minnehaha rests in the cradle of her five axle trailer. A skirt of plastic sheeting surrounds her from the waterline down.
The boat barn is three stories tall. At one end is the electric door that slides up into the rafters. Now the door is closed, protecting the boat from the cold white world outside. A few work lamps imitate the hidden sun. The space is rich in shadows.
John, one of the volunteers that spend their Saturday mornings preparing the Minnehaha for the coming season, greets me as I climb the stairs to the horse shoe shaped landing that provides access to the boat’s deck and cabin. John’s been a volunteer for 18 years, his skills as a plumber have been welcome.
He gives me a tour of the boat and a quick education about the steam engine that powers her. The engine is a triple expansion type. It uses three cylinders of different diameters (7″, 12″ and 17″) to ring as much power out of the steam from the boiler as is possible. The steam leaves the boiler at a pressure of 180 psi (pounds per square inch) and enters the engine’s first and smallest cylinder. There the steam first drives the piston down and then through some clever 19th century engineering drives the piston back up. This delivers two powerful strokes to the drive shaft that turns the propeller.
The steam then goes to the second cylinder. Because of the work done in the first cylinder, the steam has less pressure, i.e. energy, and is unable to repeat the same effort in a cylinder of equal size. That is why the second cylinder has a larger diameter. Again the double stroke occurs. In the third and largest cylinder, the steam, now down to about 35 psi, is coaxed to deliver its last bit of work.
I learned later that this was the same type of engine that powered the Titanic.
A bit later, John and another volunteer, Fred, discuss work that must be done on the boiler. They hang over the railings, on either side of the engine pit, and look at the open boiler door: some bolts need to be replaced, the fire bricks have been replaced, etc. Literally the nuts and bolts of maintaining a steam engine.
This is a photo of Fred looking into the boiler.