Three powerful Diesel-electric tugs, largest of their kind, have been commissioned as floating service stations for the U. S. Navy. The “Navajo,” “Seminole” and “Cherokee” are 205 feet long overall, each of them powered by four main Diesel engines totaling 3,800 horsepower, and so capable of handling the greatest dreanaughts in harbor maneuvers or at sea. To each of the four Diesel engines a 600-kilowatt generator is directly connected. The Diesels are twelve-cylinder, two-cycle V types. The boat can be operated from full speed ahead to full speed astern by one hand wheel on the motor panel, or by the pedestal congrol in the pilot house. Its extreme flexibility of drive permits operation at better than half speed by only one main engine at little above idling speed.