A marine powerplant on a large supertanker is a complex system made up of a number of interconnected subsystems where most functions are automated. A human operator manages the system in supervisory control mode, intervening only when an event occurs requiring his action to restore normal operations. For training marine engineering personnel to detect, diagnose, and compensate for failures, simulators at different fidelity levels are being developed. A low fidelity simulator uses information displayed on an Apple II computer terminal in conjunction with system schematics provided on paper. Details of the low fidelity simulator are described, and the results of a pilot experiment are discussed.