ELECTRIC PROPULSION OF SHIPS. 



121 



the propulsive machinery proper can be taken care of in brief time by disconnecting the dis- 

 abled unit from the source of power. 



Maintenance. — The maintenance and repairs should show to advantage because of the 

 inherent reliability of electrical machines and the absence of wearing parts. Repairs of con- 

 siderable magnitude can be made aboard the ship without removing the machinery. It is 

 difficult to imagine a casualty to any one of the electrical units which could not be repaired 

 on board the ship if circumstances warranted it. 



Study of Perfornmnce. — The electrical instruments enable accurate and convenient ob- 

 servations to be made of the performance of the screws at any instant. The electrical in- 

 struments also provide a means for quickly detecting improper performance of the screws 

 due to excessive shaft friction or damaged blades. The performance of all units as indi- 

 cated by the instruments is under the observation of the watch officer and control-room at- 

 tendants at all times. 



Electrically Propelled War Vessels in Service and Building. 



Ship 



U. S. S. Jupiter 



U. S. S. New Mexico . . 

 U. S. S. Tennessee .... 



U. S. S. Maryland 



U. S. S. California 



U. S. S. Colorado 



U. S. S. Washington . . 

 U. S. S. West Virginia 

 U. S. S. South Dakota . 



D. S. S. Indiana 



U. S. S. Montana 



U. S. S. North Carolina 



U. S. S. Iowa 



U. S. S. Massachusetts. 



U. S. S. Lexington 



U. S. S. Constellation. . 



U. S. S. Saratoga 



U. S. S. Ranger 



U. S. S. Constitution . . 

 U. S. S. United States. . 



Japanese fuel ship 



4 coastguard cutters 



Kind 



Collier 



Battleship. .. 

 Battleship. . . 

 Battleship. . . 

 Battleship. . . 

 Battleship. . . 

 Battleship. . . 

 Battleship. . . 

 Battleship. . . 

 Battleship. . . 

 Battleship. .. 



Battleship 



Battleship. . . 

 Battleship. . . 

 Battle cruiser 

 Battle cruiser 

 Battle cruiser 

 Battle cruiser 

 Battle cruiser 

 Battle cruiser 



Collier 



Cutter 



