The Firefly Thirty is of all steel construction (Circa 1983), moreover was an actual working tugboat.  She was named for a tugboat that worked Narragansett Bay at the turn of the century and, although much larger, had a very similar appearance.  She was powered by an oil fired convoluted tube boiler meeting Code and a compound steam engine built by Bill Lowe. 

Her midship body is taken up by machinery including the boiler and engine and an auxiliary 5 HP 3 X 4 Semple single cylinder that pushed  a 4.5 KW AC generator.  With this rather large amount of power Firefly was equipped with lots of batteries, refrigerator, chargers, radio, radar and a multitude of feed water, bilge, fire and other pumps.
She has a large lazarette to store towing gear and line as well as to house a small diesel generator.  One must remember that the oil fired boiler required AC to operate the burner, it being too large to conveniently operate from batteries.  Hence it was necessary to have electric power to start the boiler to make steam from which to run the steam driven generator and thereby get everything operational for vessel operation.
Below:  Firefly on launching day prior to the installation of her 7,000 pounds of lead ballast.  She required ballast as the the boat had only light living accommodations, and was quite light, despite the steam gear.

Above:  Her large four blade propeller took a good chunk out of the water while the large rudder allowed her to steer easily ahead or astern.  This view of the engine ventilation and light hatch and surrounding varnished mahogany trim indicate that she was built to be admired.  Lots of brass and scaled down side lamps added to her appeal.  Present owners have converted her to diesel.