Machinery Technician (MK) is an enlisted rating in the United States Coast Guard that is responsible for the operation, maintenance and repair of a cutter's propulsion, auxiliary equipment and outside equipment, internal combustion engines (gasoline, diesel, gas turbines), environmental support systems (heating, ventilation, air conditioning), hydraulics, generator sets, and areas of hazardous material recovery and control. They are also responsible for the engineering maintenance of any small boats assigned to their command. At smaller stations and cutters they also serve as electricians.